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General control line discussion => Open Forum => Topic started by: Rusty on April 02, 2025, 05:37:46 PM
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Hello, Please find attached questions regarding the pushrod that goes between the flap horn and bell crank.
I am scratch building a Twister and want to make the controls as best I can. I really don't know that much about it and have just been using what they gave in the kit.
Thank you.
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Simple answers: A, B, B
Steve
Sent from my SM-N986U using Tapatalk
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Simple answers: A, B, B
Steve
Sent from my SM-N986U using Tapatalk
Thank you for the reply. My concern is that in Q1, A the angle of the pushrod will apply sideways pressure on the bell crank instead of lateral. I was thinking the pressure should be straight in line with the bell crank movement.
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What Steve said A,B,B. If you are scratch building, I hope you are using metal profile horns instead of flap mounted but if you aren't, make sure the wire connecting the flaps is stiff. Same with the elevator. Also see if you can mount the bellcrank so that the pushrod is parallel to the fuselage exiting the inboard wing from the bellcrank arm to the flap horn with the bellcrank centered. This probably means mounting it "backwards" which is common.
Good luck, I love Twisters - Ken
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Thank you for the reply. My concern is that in Q1, A the angle of the pushrod will apply sideways pressure on the bell crank instead of lateral. I was thinking the pressure should be straight in line with the bell crank movement.
Well, perhaps ideally, but putting a bend in the pushrod doesn't change that. It's not like the bent pushrod will push straight back and then turn a corner. The force will still be in a straight line from one end to the other. Putting in the bend does give a way for the pushrod to flex. You want the pushrods to be straight.
If you want to keep the forces in the bellcrank plane, you would have to tilt the entire bellcrank. That is OK, but it does complicate the issue of clearance for the crank and leadouts.
I also note that using a ball link on the bellcrank end will cause a torque trying to tilt the bellcrank, since the force is being applied above the plane of the pivot. The ball is about 1/4" out of plane, the force times the 1/4" is the torque. I think you *should* use it, but you need to make the pivot resistant to this torque tipping the bellcrank up and down. This has caused severe hunting on other airplanes using traditional pivots, which were OK when new but hunted wildly when it got some wear on it.
As luck would have it, I literally just built the bellcrank and mount for a new Skyray, and can show how I do it. The bellcrank is a 3" version of my usual forked-end sandwich bellcrank. The pivot rod is a nominally 3/16" diameter titanium rod. This one was one of the orthopedic repair rods Jim Rhodes gave me, the actual diameter is about .185. The bearing is 1/4" OD 3/16" ID telescopng K&S tubing about 1 1/16" long. It spins very freely but has very small amount of rocking motion, maybe .010 at the ends of the bellcrank. The mount uses 1/8" aircraft ply (with a bunch of lightening holes) just glued to the back of the 1/4" x 5/16" medium balsa spars. This is adequate for the light pull tests I need (18-20 lbs). I use a similar method on the big airplanes, but the mount is 1/4" ply glued to the lite ply landing gear spar.
This will allow free movement while still keeping the bellcrank level under the torque applied by the ball link projecting above the top surface.
Brett
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Overkill , but seeing you asked .
(https://stunthanger.com/smf/index.php?action=dlattach;topic=51075.0;attach=289516;image)
Found Maybe 5/32 flap horns are a bit stiff , unless really Zero discrepancey under loads the go . But as things want a bit off give , it depends .
One TRIMS the cross toobs , to abouta quater . But a Foot when fitting , sees theyre true , square , perpendiculat & suchlike . as thecasemaybee .
One tends to ' neutralise ' Wire Ends etc , for No Slack Freedom . ( freeist movement ) if its all stuck up tight in the topoffthewing , when its got Diheadral .
https://stunthanger.com/smf/open-forum/francherized-twister-article/msg484827/#msg484827 Chance Ted may know a thing or two about it .
Vindy used liddle short orns , as wier weighs a bit , unless its not there . This is onee of the ' Fine Tune ' / ' Fettle ' areas . Where you GET IT RIGHT , before nailing it . ( Final assy )
Generally - a STRAIGHT RUN to the Flap Pushrod . as in , If it were 1/8 wire . One bend each end . THATS IT .Three longitudes . You Can Leave THE ENDS at three inches - Till alignments Perfected .
Then cut grovve adjacent washer to bind & solder . And cut 1/32 + outside that . Bellcrank mount & Controls is where its false economy to skimp . just threw out a plane with a inaccessable ' Z ' ed flap pushrod ,
rather'n put up with divergance. Flaps are the LIFT & tail is the PITCH . Mate .
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Some Other Bits , you can dither about for days . ( Pass / Come Back ) with it up inthetop there . To Get NO BINDING .
(https://stunthanger.com/smf/index.php?action=dlattach;topic=43652.0;attach=254920;image)
(https://stunthanger.com/smf/index.php?action=dlattach;topic=43652.0;attach=254922;image)
Solder'n The Washer , Foist One . ( Itll settle down a touch , Often bevel inner edge off washer , to get it flat against lengthwise wire . Groove , even , to get it in more still against it . Thats just a Jig .
(https://stunthanger.com/smf/index.php?action=dlattach;topic=43652.0;attach=254952;image)
Getting further away , out at the end , there .
(https://stunthanger.com/smf/index.php?action=dlattach;topic=43652.0;attach=254928;image)
seeing we're here .The 1/8 holes get 1/8 brass tube . Later Cut to 1/4 or something . dual Adjustabble .
(https://stunthanger.com/smf/index.php?action=dlattach;topic=43652.0;attach=254930;image)
And youve gotta BOIL , in baking soda - Neutralise Acid . Oil. Wash in thinner . Petrol . Boil in oil . Chain Lube . MOREYS . Hot . Wipe with a rag & thinner . Then SPRAY WITH CLEAR . or something .
No Binding . No Corrosion . And no scraps of 1/8 x 1/4 x 1/2 left after gear Leg repair to get caught in the bellcrank slot and just ' tip ' on each pass . BINDING . Needing a ' bump ' at the handle. to get past . AT ALL .
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Ken, I have a piece of 3/32" music wire connecting the flaps together. I have the bell crank mounted where the plans call for and it centered in the lead out openings.
Brett, I understand what you are saying about the direction of force. That lead me to ask another question. I did some research and read the thread where you made your laminated bell crank. That convinced me you are a REAL engineer. I know other engineers in modeling that would / could never do that.
Thank you to everyone. I am learning and improving. Sadly, my only control line flying buddy, Jim has been diagnosed with lung cancer. A few years ago I met him at one of my swap meets and he got me back into building and flying CL.
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For sooth . another tricky one up in the top there . youve a bit more freedom with it thrown in the middle . ACTUALLY . A wire Post solder ( tight fit ) in the bellcrank . With a few washers & things . And Brass Tube at
the spars , to secure it . is pretty secure & free moving . IF you leave a little vertical end flat . Like a m.m. . So It dont all tighten up as the day warms . >:(
(https://stunthanger.com/smf/index.php?action=dlattach;topic=40682.0;attach=168799;image)
Yours'd be at an angle , outa da crank arm , but maybe yer angle the crank arm angled midway to movement arc - at flap horn . One Small ' kink ' toward an ends not so bad . A BEND midway or a Z , and Yr DOOMED .
(https://stunthanger.com/smf/index.php?action=dlattach;topic=40682.0;attach=168801;image)
AAAAHHHHEEEIIIEEEEE , Geting that to Work & Not Bind / or conflict the spacve time therom ( Two things cant be in the same place at the same time ) as they confict . hit . Jam . Bind . or deflect ! . ;D
(https://stunthanger.com/smf/index.php?action=dlattach;topic=40682.0;attach=168797;image)
So , ya dunno how easy ya gottit . But if you do the Fred Flintstone 2 .m.m. steel ( .077 1 ) or 3/32 or 2.5 or . . . A 1/8 WIRE Pushn Rod , leave the ends out at three inch or so , for sighting aligning , and ease .
Till its all mid range aligned with NO binding , sticking , OR SLACK . You can leave the slack for theelevator . no worries . 5 m.m. / 3/16 th at the elevator edge , can be Good for grooveyness and stability . on a aft
C. G.
Hung from leadouts ,a hand on it . no Flap T E DEFLECTION . 3/16 at elev. T. E. o.k. . When it falls off the hook with you pushing down , get your bare foot under it real quick , so it dosnt damadge it . the Plane .
never mind about the foot .
Which brings us to solder blobs & Irons & bare feet .
and FUMES . Acid Solder , Sanding Bare . Pre tinning .
DONT SOLDER NEAR LINE STORAGE . Pref in your blacksmith area , Downwindest , So the CORROSIVE FUMES are absent from the work area .
if you store your lines ABOVE your soldering bench , Thats the end Of Em . And anything else ferrous etc up there . BE WARNED .
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Mate, I am using .092 wire to connect the flaps to the bell crank. Is a bullroarer louder than a model plane?
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With your 3/32 Flap horn , if the arms are at the inner flap faces , or say 1 1/2 apart , itll be pretty stiff . IF it were six inches , theyed be like Beringers ' Torsion Arms ' and need to be considered .
We'd decided to go to Blah Guage wire , in Oiklund , 2.7 m.m. , for Horns . On .35 ships . as it can get a bit bumpy their , in the air . In fact youd design for 40 m.p.h. winds , to fly some seasons .
the ' absorbancey ' of things , to shock loads , in rough air , you can visualise , if you try'n consider WHAT forces are absorbed - transfered - transmitted , by the ' working surfaces ' HERE .
(https://scontent.fsyd4-1.fna.fbcdn.net/v/t39.30808-6/453263281_3524566934500983_4461777945389508068_n.jpg?_nc_cat=108&ccb=1-7&_nc_sid=aa7b47&_nc_ohc=rMnUPOISEmAQ7kNvgGKmOqC&_nc_zt=23&_nc_ht=scontent.fsyd4-1.fna&_nc_gid=OuC09fxqd_IKRYDLmnYqpg&oh=00_AYGeCxfst3MDGzAPU83pcZgcBRAJdDvP7stniUsNAh4krg&oe=67F3BDF0)
Tho our widdle fings may be a widdlebit smaller , the Same Principles are still involved . Support - Manouverability - stability - . And you dont wanna get in the way , of either of them .
SO , Considering Operating Conditions . You Dont have to make it to stand 40 knots , if your not gunna fly in it . IF its just for Mild air , you only need half the durability . as it were .
So you can get a Francher Twister REAL LIGHT . So hook up to the article and study THAT . Deviations sholdnt e required . We threw in that stuff , to show you's a bit of BLACK SMITHING in miniture .
For the more isolated , do it yerself , types . Out there . H^^
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Mate, I am using .092 wire to connect the flaps to the bell crank. Is a bullroarer louder than a model plane?
No , but it carries a lot further . Mountain top to mountain top . Further Sometimes .
I thing teds got a carbon Rod in there , with wire ends . Without looking . If you asked me , Id bind a light carbon tube to it , to stiffen it . As it weighs naff all .
Some use something like 1/4 x 1/2 BASS , pushrods . as the Expansion Rate Vs Barometer matches the Timber Aeroplane .
If we flew at Mach 2 , itd grow six inches , like the Concorde . S?P But the tiber Pushrod does with the need to have it adjustable , as it stays in tune .
Those ' SAILING ' boats , Tuning was what it was all about . TRIMMING is the P. A. Term . But having no / less variable factors , gets it all hunkey dory - straight off the bench . sometimes .
Others never come right . Relieved I wouldnt have to persevere with the last concoction . As it was contrived rather than DESIGNED . So taght a lot about FLAWS . But there is a limit .
Like Learning all the differant ways to CRASH .
Not productive entirely . Flap to Bellcrank is the A1 Top Factor control system requirement . After seeing it all stays where its put . In the Air Too. ;D
Guess how many TONNES loadings in the mast & hull , and inbetween. T
RE . But theres no whitecaps . Flying coastal - there usually was - in the sailing / flying season . Year round , half of its gales .
When the winds getting good for KITES , its getting a bit much for STUNT . or is it just more challengeing . You need something for 20 / 25 knot winds , in N.Z. or youll miss weeks / months of flying .
Something for 40 , like the Folkerts , will see you right , year round .
Go Way less overengineered , for fair weather flying . But STILL . the Flap Pushrod is the No ONE Control Component - as far as operating forces - so nothin pansey their .
iMIT cONSTRUCTION oITICLE : https://www.scribd.com/document/24098001/Imitation-Article
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Brett, I understand what you are saying about the direction of force. That lead me to ask another question. I did some research and read the thread where you made your laminated bell crank. That convinced me you are a REAL engineer. I know other engineers in modeling that would / could never do that.
Oh, I think anyone *could*, it's very simple to build and it doesn't take too long. If you build one yourself, be sure to use a quality aluminum for the facing - these are .032" 6061-T6, but I think any normal engineered and heat-treated alloy would work. I also have one made of .020 titanium, that was a fun afternoon cutting that out. Not random hardware store aluminum strip flashing or of unknown grade, which has brought others to grief in the past. .032 is *great overkill* for a Skyray 35, of course.
Same with the pivot, greatly excessive but it was what I had. I do note that if the pivot wire bends under load, the bellcrank will potentially bind up. For the big airplanes, this is about 10 lbs load and it's suspended with about a 2" spacing. It's 3/16 to reduce the flexing, and it's titanium because 2.5" of 3/16 music wire is *heavy*.
Brett
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Brodak sells "Z" bend rods that are perfect for the bellcrank end and Du-Bro has solder on threaded couplers and clevis's for the flap end. Quick, simple, friction free, inexpensive and bullet proof. Don't forget it's only a model airplane.
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Brodak sells "Z" bend rods that are perfect for the bellcrank end and Du-Bro has solder on threaded couplers and clevis's for the flap end. Quick, simple, friction free, inexpensive and bullet proof. Don't forget it's only a model airplane.
The DuBro clevises are not remotely durable enough for stunt plane use and are absolutely infamous for failing at inopportune times. No commercially-available clevis, even the "heavy duty" 1/4-scale RC types, will stand up for very long. Soft solder joints are also not durable enough. If you could braze them (i.e. silver braze with a torch), that would be good enough, but that will usually destroy the clevis as it tends to unbend itself, and getting it red hot softens it even more.
This is a DuBro 2/56 Kwik-link that I was using on my rudder connection - it's only ground adjustable, does not intentionally move at all in flight, running on a plywood horn, and drenched in oil. This is after only a few years and maybe 200ish flights. I replaced it - and the new one is wearing out, too, at a high rate. This is a best-case situation, if if it fails, the airplane is unlikely to crash, and there are practically zero static loads.
(https://stunthanger.com/smf/building-techniques/why-you-shouldn't-use-kwik-links/?action=dlattach;attach=84389;image)
I am not sure why a stunt plane is so much more demanding than, say, a 1/4 scale RC model with a Quadra, but history has spoken.
Ball links are particularly important on the bellcrank-to-flap connection, because of the compound angles they have to move through, all three dimensions. Bend wire (z-bends, etc) require some clearance/slop to allow the required movement in all the dimensions. That's not entirely fatal - we did it for years - but ball links and carbon or fiberglass pushrods are also a lot easier. Screen the ball links for getting tight, pick the loose ones.
Brett
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Please use CF Pushrods and Ball Links. Every place there is metal on metal will start to wear out on the first flight, mostly from vibration. Even on Electric. For space reasons I used the DuBro safety clevis, the Black one with a retaining clip, on the flaps for Endgame III. Even brass bushed they started having slop in as little as 50 flights. I redesigned the controls for Endgame IV to use all ball links. My other control pet peeve is the bellcrank post. If you compete you are going to have a pull test that is 4-5 times anything you will have in flight short of a runaway hitting the lines at full speed. Unless reinforced the typical thin bellcrank on an 1/8" steel (even piano wire) post held centered by two wheel collars between the top and bottom of a 2" wing is going to bend. Replacing a floating bellcrank in a finished plane is only slightly less torture than waterboarding.
The picture is a bit dark but you can see the components. This is the center section of Endgame IV but it is identical to what I had in my Twister except I used a 4" bellcrank to keep the movement the same as my other planes and wider to accommodate a tricycle landing gear mount. What is important is that the center post remains removable. The 1/8" ID brass tube is sandwiched between two .3mm doublers with a hard 5/32 balsa (grain spanwise) center. The lack of any gap makes it nearly impossible to bend the pivot rod.
If you wonder why so much fuss over the controls it is because they are the most overlooked part of the plane for new fliers and the most important.
Ken
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The DuBro clevises are not remotely durable enough for stunt plane use and are absolutely infamous for failing at inopportune times. No commercially-available clevis, even the "heavy duty" 1/4-scale RC types, will stand up for very long. Soft solder joints are also not durable enough. If you could braze them (i.e. silver braze with a torch), that would be good enough, but that will usually destroy the clevis as it tends to unbend itself, and getting it red hot softens it even more.
This is a DuBro 2/56 Kwik-link that I was using on my rudder connection - it's only ground adjustable, does not intentionally move at all in flight, running on a plywood horn, and drenched in oil. This is after only a few years and maybe 200ish flights. I replaced it - and the new one is wearing out, too, at a high rate. This is a best-case situation, if if it fails, the airplane is unlikely to crash, and there are practically zero static loads.
I am not sure why a stunt plane is so much more demanding than, say, a 1/4 scale RC model with a Quadra, but history has spoken.
Ball links are particularly important on the bellcrank-to-flap connection, because of the compound angles they have to move through, all three dimensions. Bend wire (z-bends, etc) require some clearance/slop to allow the required movement in all the dimensions. That's not entirely fatal - we did it for years - but ball links and carbon or fiberglass pushrods are also a lot easier. Screen the ball links for getting tight, pick the loose ones.
Brett
Another thing that we lost when Tower/Great Planes Hobbies went away is their hardware. I think they had the best hardware as far a selection and quality went. If I was going to use a clevis on anything, I always used their 4-40 threaded clevises after seeing customers brink back examples of DuBro clevises breaking from vibration. I never had a problem with Great Planes clevises. They were made from heavier steel and Nickle plated also, so if you needed to solder anything to one it was very easy. I think their screws and fasteners were better also. When I go to swap meets now, that's one thing I look through junk boxes for. I didn't get too far into the use of. ball links to remember if they produced those or not. The Great Planes aluminum spinners were pretty good also and reasonably priced. I for sure do miss their products.
Type at you later,
Dan McEntee
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Brett and Ken, I went through my helicopter stuff and found some tail rotor carbon pushrods. I have everything to put carbon pushrods and ball kinks everywhere. The 3/32 music wire connecting the flaps has a brass tubing in the middle epoxies to the trailing edge. The plans for the Fancheruzed twister has 3/32.
I am using light weight 1/4 for the flaps.
Thanks again. Please pray for Jim.
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Brett and Ken, I went through my helicopter stuff and found some tail rotor carbon pushrods. I have everything to put carbon pushrods and ball kinks everywhere. The 3/32 music wire connecting the flaps has a brass tubing in the middle epoxies to the trailing edge. The plans for the Fancheruzed twister has 3/32.
I am using light weight 1/4 for the flaps.
Thanks again. Please pray for Jim.
I forgot what my Twister came with. I know I used a 3/32 profile horn from Tom Moris. That is strong enough because it is being driven by a horn brazed near the center of the wire. It may be just me but if you can't find one of those and the horn will be bolted to the INBOARD flap, I would use 1/8". The reason is with a thinner wire the inboard flap will have more force than the outboard and cause a slight roll in turns.
Ken
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The Friction / Bindings ' a thing ' .
(http://controlline.org.uk/phpBB2/userpix/613_thumbnail_1_1.png)
This sucker , with just a tiny bit of binding , in the flap horn , wouldnt exit straight & felt rubber . The controls were smooth & free . just wanted a push to move them .
Thought ' the controls should fall under their own weight ' was a bit over the top . ( if you had any line tension ) Aerodynamic & mass ' balance / counterweights ' can
steady it all up , incidently . In bumpy air . Supermarine anylisis states ANY Control Friction destabilises the Aircraft . Most discernable at Aft C. G. Limit .
term is ' divergent ' . Convergent is positive stabilty . Self straightening .
mechanically ' Soft ' controls , dont help none at all . Whereas I go on about them working like a ( Antique ? ) rifle bolt .Positive direct friction free exact no deflection ( Within reason ) ACTION .
The Magum with the Z in the 3/32 pushrod , I left at the Op shop . It'd NEVER go exactly where you put it . Similar ' flaw ' but ten times worst . A limit to wasteing your time .
Have A READ of Teds diatribe , as it was cutting edge stuff . and still is . I cant see he got it wrong , So WHY CHANGE IT . Exact & itll be a Pleasure to Fly . NO SHORT CUTS .
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Ken wrote: "The 1/8" ID brass tube is sandwiched between two .3mm doublers with a hard 5/32 balsa (grain spanwise) center. The lack of any gap makes it nearly impossible to bend the pivot rod."
I like Ken's bellcrank mounting as shown in the picture, but the ".3mm" made me wonder if the decimal point is a typo, as well as what the ".3mm doublers" are made from. By my calculation, .3mm is just under .012", while 3mm is just under 1/8". I'd bet it's 1/8" plywood of some sort, and IMO, "Lite Ply" would probably do just fine, but I also don't believe I've ever used "Lite Ply" for anything. There are many things I would NOT use it for. H^^ Steve
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3/32 flap joiner is perfectly OK for Twister, the control forces should be very light, even if it is a little asymmetrical due to being off-center. I use a 1/8 flap horn and 3/32 elevator horn, even on regular-sized models.
Brett
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Okay Guys, I made some progress. I installed a carbon pushrod, ball links and quarter scale control arm. I measured the plan control arm to determine which hole to put ball link.
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Pic
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Ken wrote: "The 1/8" ID brass tube is sandwiched between two .3mm doublers with a hard 5/32 balsa (grain spanwise) center. The lack of any gap makes it nearly impossible to bend the pivot rod."
I like Ken's bellcrank mounting as shown in the picture, but the ".3mm" made me wonder if the decimal point is a typo, as well as what the ".3mm doublers" are made from. By my calculation, .3mm is just under .012", while 3mm is just under 1/8". I'd bet it's 1/8" plywood of some sort, and IMO, "Lite Ply" would probably do just fine, but I also don't believe I've ever used "Lite Ply" for anything. There are many things I would NOT use it for. H^^ Steve
Carbon Fiber plate. I use .5mm where 1/8" plywood would normally go and .3 where 1/16" went. This but stiff and strong. Plate is different from matt and cloth.
Ken
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Pic
That's pretty heavy-duty alright! I am curious, why the doublers at the roots of the flaps so not go all the way to the arms on the flap joiner I use similar doublers to reinforce the hardwood inserts where the horns go in.
Also, it's perfectly good in this case, but in the future I would suggest shortening the cross-bar on the flap horn to be as short as possible, an inch and a half of music wire is stiffer than three inches.
Brett
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Pic
I hope you haven't closed it up yet. The pushrod is good. Make sure you have 6 turns of the screws on each end and the screw will go in 8. This is to center it and give you two turns either direction without letting either end get below 4 which is my comfort zone. I have flown as low as 2 but it is not safe. The other thing, and I hope I am not alone on this one. NEVER solder leadouts or lines anywhere. It is not a matter of "if" they will break but "when". Wrap them just like you do lines. I lost two planes to this in my early days when the metal VECO bellcrank was the standard. If you are doing much maneuvering of have a big motor and it pulls alot the leadouts can saw through the bellcrank is as little as 100 flights. I have seen less. And if that doesn't happen the bellcrank might saw through the leadouts. If it is not too late get a nylon one and run the wire through some thin tubing.
Ken
ps - if you have already epoxied the pushrod ends in don't forget to wrap about an inch of the rod with kevlar thread. Heavy duty sewing thread will work but it is not as sexy. This is not to meke it stronger, it is to keep the rod from splitting.
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Ken, the ball links have plenty of threads. The holes on the bellcrank have been chamfered. The is no sharp edge to cut the leadouts. What fo you recommend to keep the wire wrapping from unraveling, epoxy, shrink wrap?
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I have to agree with Ken regarding the leadouts rubbing on that metal bellcrank. Chamfering the holes might buy you some time, but it will not prevent a disaster. Even with grease, the leadout strands will start to fray. Also, as he said, never solder. Wrap just like you would do for the lines.
It might be more work, but the slotted end bellcrank, with the leadouts around a teardrop fitting, solves many problems.
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This thread covers most of what we are talking about. Even has an example of the Teardrop Jim mentioned.
https://stunthanger.com/smf/building-techniques/bellcranks-leadouts-and-sleeves/
There must be a hundred posts on this issue. Try searching "leadout","bellcrank","tubing".
Ken
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What Steve said A,B,B. If you are scratch building, I hope you are using metal profile horns instead of flap mounted but if you aren't, make sure the wire connecting the flaps is stiff. Same with the elevator. Also see if you can mount the bellcrank so that the pushrod is parallel to the fuselage exiting the inboard wing from the bellcrank arm to the flap horn with the bellcrank centered. This probably means mounting it "backwards" which is common.
Good luck, I love Twisters - Ken
I am in the process of doing a scratch build twister as well and honestly this was driving me nuts. The plans show on the wing build with the pushrod exiting the outboard wing. Yet the fuse profile shows it exiting the inboard side with the horn on the inboard side. Now that makes more sense. But now I have to ask, why the inboard side vis outboard?
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I am in the process of doing a scratch build twister as well and honestly this was driving me nuts. The plans show on the wing build with the pushrod exiting the outboard wing. Yet the fuse profile shows it exiting the inboard side with the horn on the inboard side. Now that makes more sense. But now I have to ask, why the inboard side vis outboard?
In my experience it really doesn't make any difference. The last few profiles I built I put the controls on the outside. I guess to have all the external 'junk' on one side for cosmetic reasons. It may make a difference if you put your bell crank in reversed- front line is 'up' or normal rear line 'up'. It might make sense to put the pushrod down the side that keeps it better in line with the control horn. On mine I used the front line for up but just mounted the bell crank further toward the outboard side enough to have the pushrod exit on the outboard panel. One very minor thought- the controls on the outboard side with an outboard-mounted slimer engine might keep the controls lubricated, maybe not so much if a muffler hangs pretty low. Actually putting any lube on controls isn't too wise. Any grit that sticks and accumulates will make a grinding slurry that may actually chew the controls up faster. Better to leave them dry. BEST to use Delrin parts wherever possible and never worry about wear again.
Dave
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I am in the process of doing a scratch build twister as well and honestly this was driving me nuts. The plans show on the wing build with the pushrod exiting the outboard wing. Yet the fuse profile shows it exiting the inboard side with the horn on the inboard side. Now that makes more sense. But now I have to ask, why the inboard side vis outboard?
It has a lot to do with the size and composition of your flap horn, geometry and your preference in which leadout is in front. Most are used to and as a result prefer the down line in front. If you use an adjustable leadout guide and keep them close together at the tip you would probably not notice the difference. The geometry part means that arguably, the pushrod should be as close to parallel to the fuselage as possible at neutral. Now to your question, the force exerted on the flaps when deflected in a corner at full speed is a lot more than we think. If the inboard flap has the flap horn mounted on it the entire force of the bellcrank is place on the inboard bend of the horn which allows the inboard flap to move more in a high stress turn which creates an outboard roll. The reverse is true if the horn is mounted on the outboard. To overcome this you can use a "profile horn" with the brazed horn off center, shorter horns that have the arms closer to the fuselage or thicker wire. 3/32" and 1/8" are the popular sizes. Personally, I switched to the offset metal horns long before they were difficult to find. 3/32 is fine for this type of horn but IMHO not for the flap mounted bolt on type horn. Some wire is more prone to twisting than others. If you want to see if your horn is stiff enough put one end in a vise and see how much force it takes to move the other. A "tricks" you can use for smaller wire is put the horn over the wire in whichever flap it goes on with the bolts on either side with just enough clearance to bolt on the ball links and bend the other side to be as close to the fuselage as possible. Use tubing or hardwood blocks for the wire. Never wire on balsa. Ok, there is the overkill explanation. Some may, and probably will disagree with some of this but it all comes from 65 years of learning from doing it wrong the first time.
Ken
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I am in the process of doing a scratch build twister as well and honestly this was driving me nuts. The plans show on the wing build with the pushrod exiting the outboard wing. Yet the fuse profile shows it exiting the inboard side with the horn on the inboard side. Now that makes more sense. But now I have to ask, why the inboard side vis outboard?
I would put them in the outboard wing on a flapped airplane like a Twister. The reason is illustrated above- if you drive the flap with the horn on the outside, any flex in the flap joiner will give you more outboard deflection than inboard deflection, which might cut down on the amount of tab you need on the outboard flap. It's a minor effect (like a lot of thing we worry about) and you can certainly do it the other way way around, but that would be my preference.
Brett
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I would put them in the outboard wing on a flapped airplane like a Twister. The reason is illustrated above- if you drive the flap with the horn on the outside, any flex in the flap joiner will give you more outboard deflection than inboard deflection, which might cut down on the amount of tab you need on the outboard flap. It's a minor effect (like a lot of thing we worry about) and you can certainly do it the other way way around, but that would be my preference.
Brett
I was about to comment on the difference in what you would do as an expert vs someone learning. You have done it for me. As an expert I would want what you said as a "beginner in stunt " I would want the roll to be outboard if any.
Ken
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If possible I'd use 1/8" horns. I braze mine but getting the wire that hot also softens the steel making then even more prone to flex. I few years ago I thought it might be prudent to stay with the 1/8" on the flaps but make 3/32" wire to save a dab of weight on the stab/elevator. Admittedly this was one of my bigger airplanes. The result was an airplane that was very hard to fly. It felt like I had rubber bands in the control system. That 3/32" wire flex made it impossible . I bit the bullet and tore the horn out. I put in a 1/8" wire horn and finally had a pretty nice flying airplane. The experience has me now using 1/8" wire for everything with a .35 or larger engine. Long ago I also bought some 'tweakable' horns from somebody. Had the same experience but worse, They would take their own tweak about every flight and change trim every time. Just really too soft. The 1/8" horns are nearly impossible to tweak without breaking the flaps but I just don't try. I'd rather use other means and have very solid horns.
Dave
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And, just to clarify, the construction AS SHOWN - 3/32 joiner, pushrods, etc - is perfectly adequate for a light-weight, light duty system like a Twister. The only thing I would consider changing on the current airplane might be to bush the leadouts to the bellcrank somehow. It doesn't need to be retrofitted with 1/8" flap joiner, a shorter joiner, forked-end bellcranks with titanium pivots, or any of the other things that might be good practice or necessary for a larger 40-60 piped or electric stunt plane expected to go 1000 flights with no maintenance.
I am sure that Ken and Dave would agree that showing *good practice* is one thing, going back and cutting up or disassembling a workable system that is 85% complete to try to make it "better" from a durability standpoint is quite another. Stunt fliers are extremely prone to "paralysis by analysis" and that is something that you have to fight to avoid bogging down relatively simple projects with it.
Brett
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And, just to clarify, the construction AS SHOWN - 3/32 joiner, pushrods, etc - is perfectly adequate for a light-weight, light duty system like a Twister. The only thing I would consider changing on the current airplane might be to bush the leadouts to the bellcrank somehow. It doesn't need to be retrofitted with 1/8" flap joiner, a shorter joiner, forked-end bellcranks with titanium pivots, or any of the other things that might be good practice or necessary for a larger 40-60 piped or electric stunt plane expected to go 1000 flights with no maintenance.
I am sure that Ken and Dave would agree that showing *good practice* is one thing, going back and cutting up or disassembling a workable system that is 85% complete to try to make it "better" from a durability standpoint is quite another. Stunt fliers are extremely prone to "paralysis by analysis" and that is something that you have to fight to avoid bogging down relatively simple projects with it.
Brett
I quite agree. Where we might disagree is that pointing out something that is wrong or could be better, even if it is not changed now, can and should influence how you do it on the next plane. Unless learning the pattern without in person expert guidance at the field has become significantly easier recently the plane we are talking about here will have been rebuilt several times well before any of the things we covered happen to the controls which is what I suspect you were implying.
Ken
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Yes I agree with both of you. It happens here very often that things are 'over thunk' and made too much of. I wouldn't be tearing anything up at this point to change it. It's more about things you might think about in the future AND there are quite a few others who take their que's from what they see and learn herein. Thats where I hope to be coming from with my comments. Carry on.....
Dave
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I would note that my *original* Skyray was built in about 1991 or so, and it has completely unbushed stranded leadouts straight out of the kit, running in the kit SIG nylon bellcrank, and the kit 3/32 music wire pushrod also running an unbushed hole, with a soldered washer retaining it on either end. it is adjustable only by putting a "z" bend in the pushrod and tweaking it with a big paur if pliers, and only adjustable at the elevator by unsoldering the washer and moving it to another hole
It is still perfectly functional after what is now *34 years*, and in fact the airplane won Advanced at the Golden State meet about 6 months ago. There were a few nearly-complete rebuilds of the wing and the fuse, but not to the control system. The loads are absurdly light compared to what we have to do to keep full-size airplane controls together.
Note that I had built the airplane with the notion that it was going to last about 1/2 hour, for my work buddies to fly at a work picnic (with predictable results). That didn't happen, Zach Schultz recently used it to go from "not able to fly inverted" to winning Advanced at one of the more competitive local contests in the country in about a year and a half.
Brett
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Hello Guys, I am making changes, that I can, to do what you recommend. Ken recommended I epoxy thread or wire to secure the pushrod tube to the insert. I did that by mixing up some epoxy, putting the pushrod in my drill, putting epoxy on the pushrod where the thread goes and then hand wrapping a few times and then used the drill the wrap the rest. It took, literally, minutes to do it. I then put some epoxy over the thread and smoothed it out. I'm not going to redo the leadouts where they connect to the bellcrank. All my planes from day one were made this way and none failed. The reason they don't fail is because I don't use them enough to fail. I believe, 100%, if I flew all the time it would. I don't even have anyone to fly with now. I, almost, abandoned the Twister, but didn't. I finished my Vector over a month ago and can't try it out. <poor me>
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Why can’t you try out the Vector Rusty?
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Hello Guys, I am making changes, that I can, to do what you recommend. Ken recommended I epoxy thread or wire to secure the pushrod tube to the insert. I did that by mixing up some epoxy, putting the pushrod in my drill, putting epoxy on the pushrod where the thread goes and then hand wrapping a few times and then used the drill the wrap the rest. It took, literally, minutes to do it. I then put some epoxy over the thread and smoothed it out. I'm not going to redo the leadouts where they connect to the bellcrank. All my planes from day one were made this way and none failed. The reason they don't fail is because I don't use them enough to fail. I believe, 100%, if I flew all the time it would. I don't even have anyone to fly with now. I, almost, abandoned the Twister, but didn't. I finished my Vector over a month ago and can't try it out. <poor me>
Rusty I fly about 85% of the time by myself. Just make a decent stooge and go fly. Just be extra careful to stay out of the prop when you are by yourself. Go slow and think about where you and your hands are!
Dave
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Twisters love to fly solo. I kept mine at my office where I could sneak in a few. Electric makes it easy - and clean!
Ken
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Why can’t you try out the Vector Rusty?
I don't have anybody to help, like hold it when I start it and launch it, etc. I'm sorry I brought this up. I know it is whining. I know I could make some kind of stooge, but flying to me is not a solitary activity. To me it is comradery.
Thanks for asking.
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2.4 RC is best. No pull cord to mess with. No spikes required
A $34 radio, four D-cells, any old servo. 2x4's for weight. .
The radio effectively cost NOTHING, since I needed it for scale & carrier. The release is hooked up to the pushbutton channel 3.
It's great to have flying buddies, but it's handy to be able to get in a quick test flight without having to round somebody up.
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2.4 RC is best. No pull cord to mess with. No spikes required
A $34 radio, four D-cells, any old servo. 2x4's for weight. .
The radio effectively cost NOTHING, since I needed it for scale & carrier. The release is hooked up to the pushbutton channel 3.
It's great to have flying buddies, but it's handy to be able to get in a quick test flight without having to round somebody up.
Thank you. What do you do when it lands opposite your launch area? Do you roll up your lines, move the airplane back and roll them out again?
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The old screwdriver in the thong trick. Stick a screwdriver in the ground or a crack in the concrete or whatever. Hook your thong around it. Go get the plane and walk it back to the stooge.
Ken
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I made a holder from an old wooden kitchen cutting board with a piece of wooden closet pole (10-12") sticking straight up from it. I keep it near circle center. When I land I lay my handle on it then go pick up the plane and walk it around with the holder keeping the lines off he ground.
Dave
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A friend and flying buddy here, Bob Arata, used a 5 or 10 pound weight lifting weigh, and had a wooden dowel or length of conduit with a big washer on the end that he would use for holding his handle while walking back with the airplane to his stooge. Then he could pull the dowel out and it would fit in his flight box and the weight would lay flat.. I have seen guys use a gallon milk jug filled with water to give it some weight and depending on your handle it can hook on the top of the jug, or you can put the thong on it.
Type at you later,
Dan McEntee
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Thank you Dave and Dan. I will be able to fly alone now.
The Twister is coming along. I got the wing, mostly finished. I made a weight box and adjustable lead outs. I found some nylon and made a guide. I am happy with how it turned out. I made the fuselage and added 2" to the tail, per Francher's plans. I am going to put 1/4" tail feathers on it. Today I was in the process of drilling the engine mount holes, when I discovered the FP 40 I am using has the bolt holes drilled out to 6/32. I'm not putting that large of a bolt on it. I will find another engine with stock bolt holes so I can use 4/40. I will post pictures
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Thank you Dave and Dan. I will be able to fly alone now.
The Twister is coming along. I got the wing, mostly finished. I made a weight box and adjustable lead outs. I found some nylon and made a guide. I am happy with how it turned out. I made the fuselage and added 2" to the tail, per Francher's plans. I am going to put 1/4" tail feathers on it. Today I was in the process of drilling the engine mount holes, when I discovered the FP 40 I am using has the bolt holes drilled out to 6/32. I'm not putting that large of a bolt on it. I will find another engine with stock bolt holes so I can use 4/40. I will post pictures
If you can't find am acceptable replacement, see if you can bush the drilled out hole with a short length of 5/32" brass tubing. That had a 1/8" ID and a 4-40 screw should pass through that. If you can verify that the centers of the holes are accurate still, you could ream out the hole until the tubing fit snuggly and if there are any gaps, fill them with JB-Weld. Its a little work but worth it .
Type at you later,
Dan McEntee
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How about Washers .!
(https://m.media-amazon.com/images/I/11zftTsUMzL._AC_UF894,1000_QL80_.jpg)
Thisis wotcher need . VD~ " Socket Shoulder Screws/Shoulder Bolts 4-40 X 1/4 (Pack of 500) "
Theres electronic ones too , shoulder / stepped bolts . We can start a new trend in engine mounting bolts . ;D
(https://5.imimg.com/data5/NQ/US/MY-3106632/shoulder-bolt-500x500.jpg)
Or , Like E Says , throw a bitta brass toob onit .
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Thank you Dan and Mate Spencer, I agree and have done exactly that. McMaster Carr sells spacers that are perfect to bush down the 6/32 hole to a 4/40. I bought about 12 of them years ago and fixed 3 engines. However, the spacers are reasonable, shipping is not. It is cheaper to get a good used crankcase. I texted Bobby and he is going to send me one. I have successfully got a solid bolt down by putting j b weld on the bolt using the theory Mate Spencer shows. You put a washer on the bolt and put jb weld below it, the width of the mount lug. When that dries, put the bolt in a drill and use a file to turn it down to the right size. I have done it and admit it, even though I have been called a "red neck engineer" for it. However, I got credit with the man! Recently, I sent him 4 brand new 15 engines to sell in his ebay store. Right now I can get about anything he has listed w/o cutting back on my church offerings.
Addendum: Dan, such is not the case here. The holes are hogged out with a dremel tool. They are elongated and enlarged. The spacers I had would have fixed it as you say jb welding them in. I have used brass tubing as you suggest also, when they are not that opened up. What is the adjective you use to describe someone who ruins the lugs on a brand new engine?
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Okay, Guys; I have something to discuss and show. I have the twister framed out and make as assessment of where I am in terms of success.
1) I deem it right now a failure.
A. The plane weighs 38 oz and has no covering or paint.
B. The plane is very nose heavy.
2) Construction.
A. The plane is Francherized, i.e. weight box, adjustable leadouts, 2" extended fuselage, reduced size rudder, enlarged flaps and elevator, 1/4" flaps and tail surfaces, carbon fiber pushrods and ball links on all ends.
B. The plane has a OS FP .40 with tongue muffler.
3) Correction. (Input requested)
A. The nose will have to be shortened and the engine moved back. How much??
B. To lighted the plane, I am thinking for using a 1" hole saw and cutting holes in the fuselage. How many and spacing?
C. The spinner can go.
D. The engine can be changed to a lighter one, but will that be needed?
4) Where is Mate Spencer when you need him?
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picture
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Cover it, paint it, add the tailweight if needed and go fly it.
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1) I deem it right now a failure.
A. The plane weighs 38 oz and has no covering or paint.
B. The plane is very nose heavy.
Not even close to a failure. My Twister (in pix a few posts above) weighed in at 52 oz and balanced about 1" back from the LE. It once put up a 535 in profile. It has a very good airfoil and can easily carry the weight. You are going to add 3oz (weight) of fuel and about 4-5 oz for finish. Before you go cutting it up, take something that weighs about 1 1/2oz and put it on the wing at the flap line and see where it balances. That is about where it will balance fueled. The plans show the CG unfueled so do it again this time with 4oz on the wing TE. Bet you are not still thinking it is nose heavy.
Some comments on lightening. First, where does it balance "as is". It should be at about the LE. You could shorten the nose about 1/2" with out much difficulty but let's make sure you need to first. I assume you have the wheels that far forward to fly in rough grass. You can save a bunch of weight with some lighter wheels and move them back about an inch. If I remember right the wheel hubs on the plans are right at the LE, maybe a touch behind. Same with the tank. It is good to have it close to the engine but not critical. That spinner looks huge. If you get it covered and a few coats of dope on it and it still feels nose heavy, then is the time to start cutting. If I remember the motor mounts are about 2 inches longer that the motor cutout. That gives you about a half inch to play with. The main reason I would be against cutting into the nose is that the motor mounts are the main transmitters of vibration to the rest of the fuselage. Shortening them by moving the motor back may cause a vibration problem. I stress "may".
Keep in mind that any weight you save aft or the intended CG will probably result in you having to add it back as tail weight and you have weakened the fuselage in the process. Also keep in mind that the weight of these planes back when they were designed was to accommodate a Fox 35. Todays motors are considerably more powerful.
Ken
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Not even close to a failure. My Twister (in pix a few posts above) weighed in at 52 oz and balanced about 1" back from the LE. It once put up a 535 in profile. It has a very good airfoil and can easily carry the weight. You are going to add 3oz (weight) of fuel and about 4-5 oz for finish. Before you go cutting it up, take something that weighs about 1 1/2oz and put it on the wing at the flap line and see where it balances.
Some comments on lightening. First, where does it balance "as is". It should be at about the LE. You could shorten the nose about 1/2" with out much difficulty but let's make sure you need to first. I assume you have the wheels that far forward to fly in rough grass. You can save a bunch of weight with some lighter wheels and move them back about an inch. Same with the tank. It is good to have it close to the engine but not critical. That spinner looks huge. If you get it covered and a few coats of dope on it and it still feels nose heavy, then is the time to start cutting. If I remember the motor mounts are about an inch longer that the motor cutout. That gives you about a half inch to play with. The main reason I would be against cutting into the nose is that the motor mounts are the main transmitters of vibration to the rest of the fuselage. Shortening them by moving the motor back may cause a vibration problem. I stress "may".
Ken
Thanks for the info. I am going to move the engine back and reassess where I at. I made the rudder adjustable. With ball links the controls are amazingly smooth.
The maple mm beams are about 5 inches from nose. Somewhere I read the nose should be shortened, but plans did not call for it. I agree moving tank back and losing spinner will help,
Thanks again
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It is a simple thing to Dremel out the back of the motor cutout without having to damage the doublers. Do yourself a favor and leave the blind nuts in for the current hole settings and drill new ones. When I did this kind of stuff I would plug the old holes with balsa so they wouldn't become fuel soaked and could be reopened easily. You just might want to move the engine back. The plane is looking good. One thing I noticed, and this is really personal preference, but I think the bellcrank to flap pushrod goes in the top hole of the flap horn on a Fancherized. You are most likely going to need less flap movement than elevator and it will be easier that way.
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It is a simple thing to Dremel out the back of the motor cutout without having to damage the doublers. Do yourself a favor and leave the blind nuts in for the current hole settings and drill new ones. When I did this kind of stuff I would plug the old holes with balsa so they wouldn't become fuel soaked and could be reopened easily. You just might want to move the engine back. The plane is looking good. One thing I noticed, and this is really personal preference, but I think the bellcrank to flap pushrod goes in the top hole of the flap horn on a Fancherized. You are most likely going to need less flap movement than elevator and it will be easier that way.
You don't miss anything, do you? I struggled with that because the ball links (too large) will not allow me to locate them where it is specified. To try and compensate for that I have the elevator in the most outside hole. The twister plans and the francerized have them located opposite of each other on the flap horn.
I was thinking of moving the engine back to where the front lug bolt holes on the engine will use the back bolt holes on the plane. That is moving it an inch or so. What do you think?
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Even at 38 ounces as it sits, a typical finish for a model that Windy built in his videos was 10 ounces and that was traditional dope finish with lots of clear. Even if you did that it would be 48 ounces and that would still be a pattern capable airplane. If you go iron on covering for the wing and tail and spray can for the fuselage, you might be 5 to 7 ounces more. Well within the "I'll take it!" range!! Resist any temptation to cut anything until you relocate your engine and such. Keep in mind that adding any finish to the tail end has more effect that the rest of the airplane as far as balance. Look at the airplane from the top and notice how much of the finish, including iron on covering, will be behind the main spars!! That means behind the balance point. Don't put the cart ahead of the horse!! A bare bones airframe will be nose heavy with the engine and tank installed.
The only things I might have cautioned you on was replacing the balsa spars with spruce but that wasn't much of a penalty, and not cutting out the ribs in the outboard wing like you did the inboard. Lots of airplanes wind up having too much weight out there even before the tip weight is added. I have learned to build a model where it is balanced on the roll axis if it has equal length wings. If it was something with 1 to 2" of inboard wing offset you could stand the weight better. If everything is aligned correctly, that's the first thing you want to achieve and the most important. Just do your final sanding after moving the engine and re-evaluate. I think you are going to be just fine.
Type at you later,
Dan McEntee
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Youll Need To . If you put the S T .60 in it . ;D S?P LL~
Um . Mounting Plates . steel or ally , under the lugs . Tapered for offset if reqd. Spead the load . and you fill the old ( engine ) holes with ayrldite 7 file flush , when youve made up your mind !
Acly , Steel Plates say 10 x 30 metric things , drilled & tapped ( steel ) woukld spead the nut load too . CRUSHIBNG soft bearers is a bear . But Heart Oak / Maple should take it .
Weve spliced new fronts on a bearer or two . When neccesary .
MOVINGIT .
Put the C G onnit . Pull the motor back & forward. Use a elestic band . or masking tape . with the b great 3030 muffler , Itll need to go back . but Id still have it 1/4 forward . Of the plan C G .
the Tower .40 mufflers the samme . But HALF the WEIGHT .
As in use a soft pencil / marker pen , put a line under on the c.g. , or on a bit of tape . Balance on someting under each side . If it falls fwd Yr o.k. , if it falls back , yr not .
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Thanks for the info. I am going to move the engine back and reassess where I at. I made the rudder adjustable. With ball links the controls are amazingly smooth.
The maple mm beams are about 5 inches from nose. Somewhere I read the nose should be shortened, but plans did not call for it. I agree moving tank back and losing spinner will help,
Thanks again
Don't do anything until you have at least most of the finish on it. Almost all the finish will be behind the CG, so will move it back.
Brett
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The twister plans and the francerized have them located opposite of each other on the flap horn.
Nothing wrong with that. It is better than having ball links colliding. With that arrangement you pick the hole that will give you the desires flap movement. Mine was set to 30 degrees each way. Then you use the elevator horn to give you whatever you want. It should be more than the flaps. Mine was 40. That is a lot more than you need but it is the ratio that matters. I really wish you would hold off on the cutting the nose until you get the majority of the finish on. If you do need to move it, it is best to know exactly how much.
Ken
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Guys, I pulled the trigger and did it. I moved the engine back to where the front holes in the engine bolt to the rear holes on the fuselage. It went very quickly with my Craftsman scroll saw. I cut the fuselage front off the same clearance behind the thrust washer as was before. I put everything back on, but the spinner. Can you believe it balances PERFECTLY about 3/16 in front of the spar, where the plans call for. Man, I never imagined this would be so easy,. The plane is now 35 oz and change.
As Gomer said, thank you, thank you, thank you. I'm back in the ball game.
Rusty
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Guys, I pulled the trigger and did it. I moved the engine back to where the front holes in the engine bolt to the rear holes on the fuselage. It went very quickly with my Craftsman scroll saw. I cut the fuselage front off the same clearance behind the thrust washer as was before. I put everything back on, but the spinner. Can you believe it balances PERFECTLY about 3/16 in front of the spar, where the plans call for. Man, I never imagined this would be so easy,. The plane is now 35 oz and change.
As Gomer said, thank you, thank you, thank you. I'm back in the ball game.
Rusty
With no finish it should be about on the LE. You are going to be terribly tail heavy.
Ken
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Dan, the Fancherized Twister has spruce spars.
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With no finish it should be about on the LE. You are going to be terribly tail heavy.
Ken
Okay. Being that I did not drill any new holes, I can move it forward. There is plenty of room to do that. I will move on the covering it and putting some dope on it. I will drill the final motor mount holes when I have it covered and painted.
Thanks
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Okay. Being that I did not drill any new holes, I can move it forward. There is plenty of room to do that. I will move on the covering it and putting some dope on it. I will drill the final motor mount holes when I have it covered and painted.
In fact, I could use the original holes if needed.
Thanks
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Okay. Being that I did not drill any new holes, I can move it forward. There is plenty of room to do that. I will move on the covering it and putting some dope on it. I will drill the final motor mount holes when I have it covered and painted.
Thanks
Just finish it, and see where it comes out, add weight if necessary.
Brett
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Okay. Thanks Brett.
Please see what I did.
PS: Ken what do you see wrong with the engine?
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Okay. Being that I did not drill any new holes, I can move it forward. There is plenty of room to do that. I will move on the covering it and putting some dope on it. I will drill the final motor mount holes when I have it covered and painted.
Thanks
By jove I think he's got it.
Ken
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Dan, the Fancherized Twister has spruce spars.
Well it's not a big deal but look at the plan again. You can reshape the nose a bit now also. What size spinner was that yellow one you had on there? I usually stick with a 2" or less spinner and a Tru-Turn or Great Planes aluminum spinner will have a flat backing plate that will fit easier. SIG plastic spinners had a flat back plate also if you have any of those laying around. The DuBro and Goldberg brands have that offset that has to be allowed for. A 2" spinner will let you use a starter if you want/need to, blend in nicely at the nose, and not be too heavy. An aluminum hub nut like the Higgley unit is a good substitute.
Have fun!
Dan McEntee
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Okay, Guys; I have something to discuss and show. I have the twister framed out and make as assessment of where I am in terms of success.
B. To lighted the plane, I am thinking for using a 1" hole saw and cutting holes in the fuselage. How many and spacing?
Cutting holes in the fuselage will not save you much weight. I just cut a 1" disk from the heaviest 1/2" sheet balsa I have. (It has to be the hardest and heaviest piece of balsa that I have ever had, at least 10# wood, probably a lot more - it has been in my stash for more than 50 years.)
The weight of this 1" disk is 0.9 grams. If you cut 7 1" diameter holes from this heavy piece of wood, you would save all of about 1/4 ounce.
Keith
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Cutting holes in the fuselage will not save you much weight. I just cut a 1" disk from the heaviest 1/2" sheet balsa I have. (It has to be the hardest and heaviest piece of balsa that I have ever had, at least 10# wood, probably a lot more - it has been in my stash for more than 50 years.)
The weight of this 1" disk is 0.9 grams. If you cut 7 1" diameter holes from this heavy piece of wood, you would save all of about 1/4 ounce.
Keith
Hello. Last night I did some studying and that is what I found. I agree 100%. No holes! However, I discovered another way to lose weight and not hurt strength much. Quoting Tony Montana, I said, "Say hello to my little friend" and pulled out my mouse sander and 80 grit pad. I sanded a taper on the fuselage on the top and bottom and tapered the front top and bottom at the nose to where a 2 1/4" spinner could be used. (I used table sander to do that.)
Okay, now for the moment of truth. The bare airframe without horns, pushrod, engine, landing gear, motor, tank, weighs 21 ounces and some change. Is that within useful range?
Thanks
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Hello. Last night I did some studying and that is what I found. I agree 100%. No holes! However, I discovered another way to lose weight and not hurt strength much. Quoting Tony Montana, I said, "Say hello to my little friend" and pulled out my mouse sander and 80 grit pad. I sanded a taper on the fuselage on the top and bottom and tapered the front top and bottom at the nose to where a 2 1/4" spinner could be used. (I used table sander to do that.)
Okay, now for the moment of truth. The bare airframe without horns, pushrod, engine, landing gear, motor, tank, weighs 21 ounces and some change. Is that within useful range?
Thanks
You are worrying about this FAR TOO MUCH!. Just build it and it comes out how it comes out. You haven't done anything to make it excessively heavy, it will be fine well up into the low 50's, and you are headed to the low-mid 40's. You have a modern 40, you have such overkill power compared to the original Fox 35, you an handle A LOT of weight.
I might even suggest you throw away the scales and don't check it any more. Weight does matter some, but I have yet to see an airplane that was unflyable strictly due to weight as long as the engine ran properly and it was in-trim. I have seen *lots* of airplane that were super-light, but nonetheless flew like crap because of inappropriate trim or engine setup - or that fell apart in a few dozen flights.
The obsession with weight, particularly with beginners/low-time pilots, is a toxic notion in stunt, lots of people give up pre-emptively or make themselves miserable worrying about weight, when the things that matter - accuracy of construction/workmanship, control systems, trim, and engine setup are afterthoughts.
Build the airplane the best you can, finish it the best you can, it balances where it balances, add weight to the nose or tail to balance it properly (start at about 20% of the average chord) regardless of how much it is, then trim it. You may run into limitations due to weight eventually, but not now, and predict (after doing this to varying degrees of attention for 50+ years) that you will outgrow the airplane or build another one long before you get to the point that 3-4 ounces matter to you.
Weight does matter, to an extent, but after reading back through this thread, I think you are applying far to much relevance to weight in what appears to be a perfectly good job that is about the norm for these sorts of airplanes. Carry on the good work, and I wasn't kidding - put the scales away and just build it.
Brett
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PS: Ken what do you see wrong with the engine?
I don't know about Ken, but it appears you have drilled a hole (PA spraybar-sized) in your engine. As above, carry on anyway, there are a lot of engines that fit the same mounts.
Brett
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Okay. Thanks Brett.
Please see what I did.
PS: Ken what do you see wrong with the engine?
Rusty if you were referring to the mounting holes-don't worry the least about it. Thats what washer are for. Many old engines I have acquired you could drive a truck through. Wish whoever had them didn't but it really made no difference. Clamping bolt pressure will hold the engine down. In regards to the idea of making lightening holes in the profile fuselage-don't. You need that thing as stiff as possible and have enough mass to absorb some vibration. The jest of what many here are trying to say is-don't overthink it- you got this! Finish it, fly it and if necessary make some changes to the next one if you think it needs it.
Dave
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Rusty if you were referring to the mounting holes-don't worry the least about it. Thats what washer are for. Many old engines I have acquired you could drive a truck through. Wish whoever had them didn't but it really made no difference. Clamping bolt pressure will hold the engine down. In regards to the idea of making lightening holes in the profile fuselage-don't. You need that thing as stiff as possible and have enough mass to absorb some vibration. The jest of what many here are trying to say is-don't overthink it- you got this! Finish it, fly it and if necessary make some changes to the next one if you think it needs it.
Dave
Yes, I was referring to lightening holes. I'm not doing that. The fuselage needed work because it had square edges. I rounded the edges of the front doublers and put a taper on the top and bottom of the fuselage behind the doublers. I do this on all my profile planes. Now I will start the part I hate, finishing it. I'm shooting for a -5 pointer. If enter it in a contest they will have to deduct 5 points from my score. That's good for me; it's better than them saying it's not a plane, it's a modern art masterpiece and I cannot enter it.
Thanks very much.
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Yes, I was referring to lightening holes. I'm not doing that. The fuselage needed work because it had square edges. I rounded the edges of the front doublers and put a taper on the top and bottom of the fuselage behind the doublers. I do this on all my profile planes. Now I will start the part I hate, finishing it. I'm shooting for a -5 pointer. If enter it in a contest they will have to deduct 5 points from my score. That's good for me; it's better than them saying it's not a plane, it's a modern art masterpiece and I cannot enter it.
Thanks very much.
Most of the contests I attend do not award appearance points for profile. We are even dropping them from PA at our local contests this year.
Ken
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Yes, I was referring to lightening holes. I'm not doing that. The fuselage needed work because it had square edges. I rounded the edges of the front doublers and put a taper on the top and bottom of the fuselage behind the doublers. I do this on all my profile planes. Now I will start the part I hate, finishing it. I'm shooting for a -5 pointer. If enter it in a contest they will have to deduct 5 points from my score. That's good for me; it's better than them saying it's not a plane, it's a modern art masterpiece and I cannot enter it.
Thanks very much.
Without a builder of the model rule Rusty you can just say you bought it at a flea market......
Dave
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Without a builder of the model rule Rusty you can just say you bought it at a flea market......
Dave
Or, I could say it came from an art sale in the section where they sell popsicle stick and beer can airplanes.
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Or, I could say it came from an art sale in the section where they sell popsicle stick and beer can airplanes.
Now that is art I can understand!
Brett
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You are worrying about this FAR TOO MUCH!. Just build it and it comes out how it comes out.
Brett
I agree with Brett. Imagine that!
38 OZ no covering, you could add a concourse finish at 12oz and still be in the ballpark. If you finish with MonoKote and painting the fuse, I would be surprised if it hits 45oz
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I agree with Brett. Imagine that!
38 OZ no covering, you could add a concourse finish at 12oz and still be in the ballpark. If you finish with MonoKote and painting the fuse, I would be surprised if it hits 45oz
We probably agree on almost everything.
This airplane is plenty in the ballpark, and having an heavy airplane that is finished and flies is still better than one that is light but never gets done. As Bob says, you are headed to low-mid 40's, that's plenty good enough, particularly with massive power boost.
Brett
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I am in the process of finishing it. Yesterday I sanded it with 2 grades of paper, filled in knicks, and sanded again. While doing this in my mind I heard: "Danial Son, <oriental sounds - grunting> SAND AIRPLANE. Either build airplane to fly or build airplane to hang up, in between bring garbage bag."
It is coming along. I have one coat of dope on it. Maybe tomorrow I will put polyspan on.
Thanks for everything. PS: Yes, I watched Sparky's polyspan video.
Rusty
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Hey Guys, I have the twister covered and 3 coats of dope on the whole thing. How many coats does it need to put color on? It now weighs 24 oz.
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Eight
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Eight
Thinned I hope! I use a quick seal with nontauting dope on polyspan and it is ready for sanding at 3, 6 to color.
Ken
A note to Rusty. The twister wing is easily warped. Check it after each coat.
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Paint it two rib bays at a time. Top and bottom.
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Paint it two rib bays at a time. Top and bottom.
Thank for that outstanding advice. Unfortunately, I have already done 3 coats, alternating top to bottom. Fortunately, I overbuilt the wing by using spruce spares, rock hard leading edge stock and trailing edge stock. It appears to be okay.
Today, I had my swap meet at Sundancers. It was very good. I made 195.00 in sellers fees. I bought a bunch of light weight wheels, so I will swap out the heavy wheels. Also, I got a brand new LA 40 for 20.00. (R/C version)
Happy Easter everybody.
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Thank for that outstanding advice. Unfortunately, I have already done 3 coats, alternating top to bottom. Fortunately, I overbuilt the wing by using spruce spares, rock hard leading edge stock and trailing edge stock. It appears to be okay.
Today, I had my swap meet at Sundancers. It was very good. I made 195.00 in sellers fees. I bought a bunch of light weight wheels, so I will swap out the heavy wheels. Also, I got a brand new LA 40 for 20.00. (R/C version)
Happy Easter everybody.
The twister wing is prone to *twisting* more so than warping. Find a way to keep it square while it is drying. Mine was monokoted and I had to straighten it up allot, but as easily as they warp, they unwarp. Looking good!
Ken
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Hello Guys, I finally got the Twister finished.
I'm not all that happy with how it turned out, but what happened, won't happen again. What I'm not happy has to do with our discussion of it balancing. I reported I thought it was nose heavy, which was before it was painted. In a knee jerk reaction due to some saying I needed to move the engine back, I did cut the fuselage to where the engine would move back and cut the front off for that location. Then someone said, it was a big mistake because when I paint it the reverse will be true and it will be tail heavy. WOW!!!! Was that person EVER on the money. That is exactly what happened. I did not move the engine from it's original location, but the grave error I made was cutting off the front of the fuselage to where I could not move the engine forward to balance it. That means I had to add about 3 to 4 ounces to balance the plane. Instead of the light weight tongue muffler, I put the stock muffler on and had to put a 1.25 oz heavy prop nut under the spinner. Because of all this stupidity on my part the plane weighs 47 ounces. It could have been around 44 or less if I didn't cut the nose off. (Quoting Gomer, dumb, dumb, dumb)
I am happy with the finish. I don't have much money in it. I used Michael's acrylic paint with was less than 5 bucks. I put 2 part urethane over that. The controls work perfect and very smooth. I did not have to put any tip weight because I didn't cut lead out holes in those ribs. I did have to adjust the lead out slider to get the nose to lean out when suspending the plane by the lead outs. I have an adjustable rudder and put a slight amount of right rudder. I put a 1 degree shim under the engine lugs.
Anyway, I appreciate all the help (good and not so good) I was given.
Rusty
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Rusty, I think you will be pleased at how well it will fly at that weight. If everything is straight and aligned well, just put a few short tank flights on it to feel it out. Have someone eyeball to see if it flies level with the lines and once you have tried inverted flight and feel comfortable, have them eyeball that also. Ease into how it feels up high in the 45 degree range, try a few loops and such as you move along. Start out with some 60 foot, .015" lines and a lap time about 5 to 5.4 seconds or so and adjust from there for your comfort zone. The model looks great!! Have fun with it!! The next one can be a 40 ounce wonder!! When you start adding in all the wood for the Fancher mods, it does add up in the final weight unless you have all 4 pound Ecuadorian gold in it!! I think you did OK.
Type at you later,
Dan McEntee
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Love the traditional colors. Doesn't the push rod from the bellcrank usually go on top of the flap horn?
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Twister looks great. remember this was not designed to be a full fledg nationals aerobatic plane. Just go fly and have fun. D>K
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Love the traditional colors. Doesn't the push rod from the bellcrank usually go on top of the flap horn?
See screen shot of fancherized twister flap horn. It is different than stock plans. I had to move the clevis closer to the elevator because I was getting more flap movement than elevator.
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Hello Guys, I finally got the Twister finished.
I'm not all that happy with how it turned out, but what happened, won't happen again. What I'm not happy has to do with our discussion of it balancing. I reported I thought it was nose heavy, which was before it was painted. In a knee jerk reaction due to some saying I needed to move the engine back, I did cut the fuselage to where the engine would move back and cut the front off for that location. Then someone said, it was a big mistake because when I paint it the reverse will be true and it will be tail heavy. WOW!!!! Was that person EVER on the money. That is exactly what happened. I did not move the engine from it's original location, but the grave error I made was cutting off the front of the fuselage to where I could not move the engine forward to balance it. That means I had to add about 3 to 4 ounces to balance the plane. Instead of the light weight tongue muffler, I put the stock muffler on and had to put a 1.25 oz heavy prop nut under the spinner. Because of all this stupidity on my part the plane weighs 47 ounces. It could have been around 44 or less if I didn't cut the nose off. (Quoting Gomer, dumb, dumb, dumb)
I am happy with the finish. I don't have much money in it. I used Michael's acrylic paint with was less than 5 bucks. I put 2 part urethane over that. The controls work perfect and very smooth. I did not have to put any tip weight because I didn't cut lead out holes in those ribs. I did have to adjust the lead out slider to get the nose to lean out when suspending the plane by the lead outs. I have an adjustable rudder and put a slight amount of right rudder. I put a 1 degree shim under the engine lugs.
Anyway, I appreciate all the help (good and not so good) I was given.
Rusty
Looks like the fuel tank could go a bit further north which will help a little. Plus, there is nothing wrong with shorter fuel lines. And maybe use an APC sport prop which is way heavier than wood. Then decrease the spinner nut weight as appropriate.
And the model looks great nonetheless!
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Looks like the fuel tank could go a bit further north which will help a little. Plus, there is nothing wrong with shorter fuel lines. And maybe use an APC sport prop which is way heavier than wood. Then decrease the spinner nut weight as appropriate.
And the model looks great nonetheless!
Thanks. Actually, I have and am stil considering putting heavier wheels and an APC prop. I will have to cut the spinner opening if I do. However, I don't have an appropriate size APC. The prop on it now is a new TF wood 11 x 5 (old school) prop. I would like to see if the heavy prop nut gives a smoother engine run, due to the flywheel affect.
BUT, I still have no solution to getting somebody to fly with. My flying buddy (Jim) is still too sick to participate. I have a back log of planes to test. I have my ringmaster that I did fly twice and made some changes to that needs flying. I have my Vector that I have never flown and now the Twister is waiting. I'm not complaining, this better than having no planes. What size APC do I use for a FP40?
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Thanks. Actually, I have and am still considering putting heavier wheels and an APC prop. I will have to cut the spinner opening if I do. However, I don't have an appropriate size APC. The prop on it now is a new TF wood 11 x 5 (old school) prop. I would like to see if the heavy prop nut gives a smoother engine run, due to the flywheel affect.
BUT, I still have no solution to getting somebody to fly with. My flying buddy (Jim) is still too sick to participate. I have a back log of planes to test. I have my ringmaster that I did fly twice and made some changes to that needs flying. I have my Vector that I have never flown and now the Twister is waiting. I'm not complaining, this better than having no planes. What size APC do I use for a FP40?
I cut into Dubro spinners all the time to fit a prop when needed. Not a big deal. Just remember to check the balance on the spinner.
Is your FP 40 the newer ABN design? The first-generation FP's had iron pistons and steel liners. But at some point, OS upgraded to ABN metallurgy. But OS never changed the FP designation. It is easy to see which one you have. The older iron/steel design has a bump on the side of the case.
I have a SIG Banshee which is about the same size as the Twister. I used to have a 40 FP (ABN) on it, but it was just too much engine for it. Plus, I needed to lose nose weight as the 40 FP is quite heavy. I went to a lighter OS MAX 30 and was able to lose a bunch of tail lead weight. Overall lighter model. The model was transomed and flew great. The MAX 30 power was fine for the Banshee and is probably a bit more power than a Fox 35. I am running an APC 10-5 on the MAX 30. Somewhere around 9,800 rpm.
The 40 FP will easily turn a 11-5 prop. So, I would try a 10 or 11 inch diameter prop with low pitch say 4 or even 3. You can even cut an 11" down to 10.5". You'll have to test the various props and corresponding ground rpm to achieve the lap time you want. Probably something like 5.2 seconds.
And don't be afraid to tone down the power of the 40 FP by using a smaller venturi. I believe the stock venturi for the 40 FP is 0.283". I ran my 40 FP with the venturi off of a stock 25 LA (0.257"). And even smaller ones are available from James Lee (Lee Machine Shop).