wingtip shapes

[Brian Courtice]

So many control line stunt airplanes have essentially the same wingtip design.
I'm talking about the half teardrop shaped flat plate sandwiched between wedge shaped partial ribs top and bottom. Sometimes the tips are raked forward or backward, but the design remains about the same.
My question is; why bother?

I happen to like the square tips on something like a Fancherized Twister. It's modern looking. It resembles the tips you see on current full scale aerobatic competition airplanes. It's simpler to build.

Those rounded tips seem like a throwback to the 40's and 50's and 60's when full scale single seater light airplanes tended to have rounded tips. It's no surprise that the models designed when UC became a thing had big rounded wingtips too.

So why has this been so persistent, so many decades later?
Do control line planes fly better with rounded tips, or is it just because people still think that that's how the tips on a UC model ought to look?

[Dennis Toth]

My personnel feeling is that for control line, at all but the top levels, it makes little difference and just looks good. Smooth lines appeal to a majority of people and it makes them feel like it is doing something. There have been discussions on this forum about tip shape and how it impacts the tip vortices to reduce drag but that is not our main issue with stunt same, for very high aspect ratio wings.

People have won with all shapes of wing tip. It is just what appeals to the top fliers that has a lot of influence on what a lot of other fliers will follow (this goes for engines, props, ship size, even paint). Bottom line is fly what you like, build it straight and reasonably light then trim it to fly the way you feel it fly's best.

Best,    DennisT

[Ken Culbertson]

I agree with Dennis.  It is really how it looks to you that matters.  If tip shape had a definable influence, then all of the top fliers would be using the same design.  Personally, I think swept tips are better but how much of that is simply because I like them better and for whatever reason we tend to fly things we like better.  I was hooked when I saw Lew McFarland fly his Shark 45 as a kid, been doing it that way ever since on anything I designed.

Ken

[peabody]

I think they look nifty....but that Windy's "backward" tips looked better.
HOWEVER, you can build tips out of whack, which cause trim issues.
Greenaway said "tips don't fly"

Have fun

Peabody

[Brian Courtice]

I appreciate the replys.
Bob designs the most gorgeous airplanes. His jet styled models always appeal to me very much! Love that electric twin!

I've been in a full time UC deep dive for a few months now. I spend hours every day reading forums and studying plans.

I'm sort of amazed at how little control line has really changed since...just about forever.
Even the current designs are still obsesively built from ever harder to find contest balsa using basically the same construction methods as models from decades ago.

I'm currently dusting off a few R/C models in preparation for the Joe Nall.
I've got a Flex Innovations QQ Extra 300 that is made of injection molded foam. It looks a lot like a UC stunter except for the oversized flying surfaces for doing 3D aerobatics.
It's got more wing area than my Brodack P-40. It's lighter. It's just as stiff. It's a cheap mass produced product and it flies very very well. Why cant we make a cheap, great flying injection molded Nobler or a Crossfire? Imagine a plane that was cheap, assembled in an hour, and capable of flying a competitive pattern.

I've got a few built up wood 3D aerobatic models about the same size as a 40-60 sized control line plane. Again, at least as light as my P-40. Only about 25 percent of these airframes are made from balsa. The rest is plywood. Plywood!!
Modern CAD design, interlocking laser cut parts and cheap labor assembly lines allow for designs far beyond what a typical builder is going to produce by hand cutting parts from sheet balsa. Afordable. Mass producible. Modern. Fantastic flight performance.

I know my Brodack P-40 was mass produced, but I've seen the plans. It's very much old school construction. You don't have to worry about the shortage of decent balsa when light airframes can now be built from plywood using modern methods.

Don't get me wrong. I LOVE old school designs and building methods. My new enthusiasm for all things control line will soon have me drawing lines on paper and designing stunters I can hand build from sheet balsa using little more than an Exacto knife to fabricate the parts. The building is a huge part of the appeal.

That said, I love all my mass produced r/c airplanes, and I would love to see more control line models produced the same way.
Don't hate me, but I really want an injection molded foamie control line stunter that I can buy today and fly tomorrow.

[Ken Culbertson]

There are a couple of basic reasons you won't ever see this in CL.  First and foremost to the PA community is the builder of the model rule for competition.  Second is the size of the market.  I would cost 10's of thousands to tool up for this kind of product for a potential market that is really quite small.  Any hope would be with the existing RC ready made suppliers from China. Not so sure I want to go there.  Probably other reasons as well and there are a lot of reasons it would be a good thing, just not economically feasible.

Ken 

[Dennis Toth]

Brain,
The problem is we are few in numbers that fly control line and that gets smaller for competition stunt, smaller yet for PA stunt. There have been and are ATF stunt ships. Top Flite did the Nobler when they were still in business and Brodak has several now, but they are not cheap. Many guys just like to design or build from plans or kits. It would be hard to get enough interest in a one design to cover the setup cost of a molded ship. You could convert an RC ship, but it might require some creative structuring but could be done. If you are just fun flying go for it.

Then there is the builder of the model (BOM) rule for PA stunt which knocks off your appearance points (up to 20 points) for ARF & ARC ships, which means you lose the contest (many contests are withing 5 points). Some local contests have done away with the BOM and appearance point and it would be fine there.

Best,    DennisT

[john e. holliday]

Brian, you mention a molded plane for control line that could be assembled in a couple of hours if not days capable of flying the stunt pattern.  Maybe we need to get back to basics and start promoting the fun of control line flying.  I knew a few guys that fly control line for just the fun of it and trying different things.  You mention the RC kits and it reminded me a young lad that did convert RC planes to CL and was having a ball just doing loops, eights and inverted flying.   He stated he loved watching others do the pattern when they did it but had no hankering to go that far.  Right now if I could get a local guy who wants to fly CL for fun and would come get me I have many planes he could fly.  I know Dave Trible gave away complete set ups to a couple of people after they soloed on the plane they flew.  Yes they were basic trainers that a person once he got tired of flying level laps could start doing loops and eights.  I am working on throttle controlled planes so I can control the speed and if I have too land.  But time will tell.

[Brett Buck]

The problem is we are few in numbers that fly control line and that gets smaller for competition stunt, smaller yet for PA stunt. There have been and are ATF stunt ships. Top Flite did the Nobler when they were still in business and Brodak has several now, but they are not cheap.

   I would have to disagree with you there - these consumer-level ARFs are *insanely cheap* compared to the amount of time you would take to construct one yourself. Even the Yatsenko-style RTFs are incredibly cheap for their capability and compared to a similar quality custom-built airplane, also, when you include the time it takes (not to mention the skill required). I am sure not willing to build models of that quality (or any quality at all) for 3500 "euros".

Then there is the builder of the model (BOM) rule for PA stunt which knocks off your appearance points (up to 20 points) for ARF & ARC ships, which means you lose the contest (many contests are withing 5 points). Some local contests have done away with the BOM and appearance point and it would be fine there.

 If you are (or anybody else is) losing contests by 5 points, it is not because you didn't get appearance points.

  I also note that almost everyone is struggling along with self-induced problems that in many cases would take minutes to fix, in the right situation and taking full advantage of current state of the art - even with very modest equipment.

    In either case, there is a very simple solution proven millions of times for the last 70 years - build your own airplane.

   At the NATS, yes, you can't fly it. George Aldrich built his own airplane, you want to get your name on the trophy with him - then do it like he did. Over and over, every single time the topic comes up, it's about 80:20 in favor of keeping the BOM.

    There is absolutely nothing standing in the way of an injection-molded foam CL airplane being marketed, aside from economic insanity  and certainly no significant rules impediments, aside from the one case were I and almost everyone else WANTs an impediment - the US National Championship. But the very vast majority of CL Stunt fliers will never fly at a Nationals (unfortunately), and these other supposed "problems" are all directed at the wrong part of the problem - its not the 20 appearance point that you should be worrying about, it's the other 620 flying points.

 
   It doesn't happen because it would be an economic catastrophe to embark on such a plan. If you think $200 ARFs are "too expensive", wait till you see what you would have to pay to recoup the tooling cost on injection molds with a total market of maybe 200 units. Then, a complete rank beginner with a properly trimmed and powered Skyray 35 that cost a total of about $120 to put together will blow everyone out of the water in Advanced, appearance points or no.

   Brett

   

   

[Dennis Toth]

I think I need to clarify my statement about contests being within 5 points. What I was trying to say was that at those contests that include appearance points and you elect to fly an ARF or ARC ship under current rules you can fly but will not receive the appearance point which can be up to 20 points. Point being that when at a contest with appearance points (some do include them) not receiving ANY points you will likely loose cause the top three places are generally within 5 points.

As far as cheap vs. expensive that depends on your finances. If I compare me building a ship vs. even some of the kits, what it costs me (not counting my time) is far less, so I build. I build mine from scratch or plans and enjoy all that goes with that (except for hinging and paint). I have a large stock of good balsa, several kits to build and a place to build that is comfortable. Others don't like this aspect of the hobby or have to build on a kitchen table and for them ARF's are their answer.

I do agree that in a even up contest (no appearance pts) or any contest that I fly at and I lose by 5 points or even .5 points to an ARF, it's my fault for not building a straight airframe or working on my pattern not the fact that someone beat me with an ARF. All good, we need all the flyer's we can get.

Best,   DennisT

[Brian Courtice]

Good stuff gentlemen.
I think Ken is right about the market being too small for mass producing control line airplanes.
15 years ago there were a number of ARFs offered by several kit making companies. All gone now. Even Brodack, as far as I can gather, is not going to continue importing it's ARF line.
It's really too bad.
The R/C side of the hobby is completely saturated with ARF's. Many of these offerings far exceed what an average, or even an advanced, builder could produce in terms of build quality and performance, and they cost less than it would cost to gather the materials to do it yourself. If you are an R/C guy building his own planes you are doing it because you want to, not because you have to.

Still, R/C at it's root level, is predominately a hobby for old men. Most of those old men probably flew and crashed a 1/2a control line plane or two as kids. I can't help but think that if a good looking, good flying control line model that you can assemble tonight with nothing more than a Philips screw driver and an hour or two of time were available at a tempting price, those R/c guys who are already buying ARF's by the boatload, might just treat themselves to a CL model. For nostalgias sake if nothing else.

Every time I look at my R/C  Extra 300 (The model in the photo above), I think about the possibilities.

[Brett Buck]

I can't help but think that if a good looking, good flying control line model that you can assemble tonight with nothing more than a Philips screw driver and an hour or two of time were available at a tempting price, those R/c guys who are already buying ARF's by the boatload, might just treat themselves to a CL model. For nostalgias sake if nothing else.

Every time I look at my R/C  Extra 300 (The model in the photo above), I think about the possibilities.

   I think you are missing a fairly basic point - all the guys who might have been a target market for RTF/buy-and-fly CL all moved to RC long ago, in the 70's for the most part. That's *why* RC RTF/buy-and-flies are such a big market, and of late, the *competition* RC events have shrunk dramatically with only a few exceptions. People who fly model airplanes casually were (and I quote) "moving up" to RC long before there were ARFs.

   I think what has happened to the ARF market is illustrative - Top Flite had the same idea you do, hence the first CL ARFs, the Flite Streak and the Nobler (because they had the rights to them) to cater to the sport flier/"regular flier", on the premise that this would appeal to that group. What happened?  The CL stunt regulars went out an bought them, in some cases finding the quality lacking (particularly the control system on the Noblerm which was known at times to wear out or fail in 3-4 flights), but almost none of them to these hypothetical sport fliers - because for the most part, they don't exist. So everybody already doing it ended up with one or one of the soon-to-follow Brodak offerings, but the market didn't really expand.

   So, you only market is really the existing competition fliers - which is pretty tiny - the vast majority of whom don't want to change the rules because it devalues the concept of "a subjectively-judged event combining modeling craftsmanship skills and the precise and accurate execution of prescribed aerobatic maneuvers" while still permitting everyone to participate. Among those who actually want an  ARF, expect that it will take several years to a decade of people arguing over whether it is any good or not.

    I am no businessman, but as a business, that seems like a dead loser considering the overhead. My WAG is that you would sell maybe 100 of them if they are of very high quality and you can get some "name" flier to get one and develop it for you. "Name" meaning, someone who knows how to set it up, knows how to use *modern techniques*¹ and where you can compromise and where you cannot.

    My guesstimate is that the non-recurring cost, amortized over 100 units, instead of 10,000, will lead you to a completely unreasonable unit price², and now your market has disappeared, because it's not any less than a custom-built model.

      I am not trying to talk you out of it, exactly, but you should go into such an endeavor with a clear idea what you are getting in to. I can't see it making sense, or it's a case of "how to you make a small fortune on model airplanes - start with a large fortune!"

   Brett

^{1 and 2} not to pick on Dennis, since he is a good guy, but note that he considers, say, $200, as "expensive". To sell it retail for that, your unit price for the production of the airplane might have to be as little as $30 including amortizing the non-recurring costs. Can that be done? Several large injection molds to make maybe 100 units, say the molds are $10000, thats $100 dollars/unit right there, forget the development costs, advertising, shipping (from China, presumably) then the hardware, etc. You have to consider that you can scratch-built a reasonably competitive airplane for Advanced class in a few evenings and maybe $125, and that's not some hypothetical notion:

https://youtu.be/VS6v8y7F4QA?t=262

   

[M Spencer]

I think they look nifty....but that Windy's "backward" tips looked better.

Or are they Billy's ! 

[M Spencer]

This is from 1958 . Designed for Oliver Major diesel . 3.5 c.c. , a Flite Streak for the English Aeromodellor .
Aldrich & palmer did ' Overseas Tours ' to bring Control Line ( U/C ) to the hordes .

Id think the ' Low drag ' & preocuppation with Hoerner Wingtips ( gliders ) in that Era of underpowerment
were considered benificial .
http://acversailles.free.fr/documentation/08~Documentation_Generale_M_Suire/Conception/Dimensionnement/Aile/Comparison_of_square_round_and_Hoerner_wing_tips.pdf



Used the Top version ( tip rib at 45 deg to vertical ) back in 76 , it sort of ' balanced out ' thye turns / lift
on the flat wide ( 4 in ) Phantom I built . Later version got extensions aft , trimmed till o.k. . This Low Vortice trip
decidedly stopped strong yaw in strong crosswinds . https://stunthanger.com/smf/nostalgia-30/phantom-f4ef-ish/msg635875/#new

The Long L E obviously gives a long L.E. , which as far as LIFT goes , does a lot of the work . ( ENTRY )  Aslong as the air comes of smoothly aft , you havnt disadvantaged the affair .

My opinion , Jack sheeks was a master of ' sorta scale ' and ' sorta tips ' . Whereby he got a aerodynamically efficent wingtip .
Where they LOOKED the same as the full size he had copied , but in fact were aerodynamically configured for Control Line . Wether intuitivly or by planning . Both Id think ,
He being somewhat preoccupied with Control line stunt , endless veriations / permutations wouldve been considered and catalogued mentally in his ( amongst others ) cranium ! .



So , where wingtips are in mind , a study of mr sheeks works are likely to provcide tutorage , if youve a general idea in mind . 

The principle virtue being theyre minimalist material wise , while retaining aerodynamically clean shapes . In the ' Scale stunt ' range , theyre seldom ( any / ) true scale shape ,
yet do not appear blatently ' Not Wright ' . look at his corsair and Mosquito . Brilliant and finding simple ( light ) solutions to a variety of issues . tho early heavy foam experiments
might not have been 1000 % , modern cored efforts'd bring weights ' into range ' .

My personal perception is that the plane tends to turn ' about ' the extreme span ' point , or at leastthat , the pressure at the tip ( fore & aft position - entry / exit ) is a FORCE concentration .
As in the little peacemaker you can ' feel ' the Long T E effect . on a reversed tip , you can ' feel ' the working L E more . The Max load point of the tip is where the max load is , at the tip ! 

[M Spencer]

Bob very cunningly put the WING TIP TANKS underneath , on his F 105 . Ever since I first saw pictures , Id thought the Hurricane desert tank killer , would benefit from the same configuration . Ive yet to try it . 





Though I think Bob's act as ' fences ' as well as enhance longitudunal stability & tracking . ( the MC 72 Floats are comparable aerodynamically - Score ONE for Bob ! . )
Must put hard points on the ' under build ' Hurricane , to compare . on / off .

HOWEVER . WING TIPS ! Tip Tanks . The BERRINGER has 50 % Tip Vs Root , so THICKNESS at tip is 50 % root thickness , if someone has Tip Tanks on the brain ! .
A Beringer ' starfighter ' or suchlike ( conversion ) would get a workable ' Tip tank ' diameter / length n. !

these arnt at max. tip chord , but ' out on the tip . so SIZE more appropriate , in our book . If you wanna tryem . ?


Tip PLATES on TAILPLANES were prety well used recently . Are a SIMPLE set up to ' clean up '
' wingtip airflow .



One Last throw -  detachable / taped on EXPERIMENTAL tips , youd learn sumit . low wing fings can benifit from ' evening up ' lift , upright to inverted .
Where you really notice if the airflows not stable in STUNT , is when you are . Suden shifts / breaks in flow , get planes trajectory unsettled .
So anything really knarley in the experimental dept. Mr Sheeks Fly t THEN paint it trip , or electricty to avoid oil soak .
Notta lotta point on a million dollar finish on ends that arnt ended , shape / development . A rough on the field glue & tuck / cut & add , would be intresting .




Id think DELIBERATE - LARGE tips would be in the experimental catagory ! Big Ugly Thru - Flow ones definately . But youll never learn if you never try it . 



Had radiators inem , So Tube Through . alledgedly the weight / inertia were the cause of its demise . So minimalist Lite Wt. gets less momentum / inirtia derived ' oh dear ' 's



The stabilising / tracking inluance of a TUBE out there , would have to have some influance on flight behavior .

[Ken Culbertson]

Not sure who I copied back in '63 but it is a shape that has stuck with me.  Today I simply reverse it

I wonder how a double Horner might work?  It would not disturb the design of a "Vector" type too much and it might just have some value - maybe....or not.

Cloth hinges, no mufflers, fixed leadouts - state of the art!

Ken

[Dave_Trible]

I believe tip shape has quite a bit to do with stability in turbulent air.  Way back we tried flat endplate tips on combat ships.  Those were decidedly more 'bouncy' in rough air.  My experience has told me the raked tips (forward or back) seem to yield the smoothest flying but even beyond that, from the front view,  the "v" shape rather than rounded blocks are quite a bit better in turbulence.  Could be you get some amount of shear off those edges rather than promote air wrap-around with the rounded types....your mileage may vary. 

Dave

[Trostle]

Air Ministry posted a photo of Billy with the USA-1 to show that he had those swoopy tips way back when. Even Billy would give credit to Jerry Worth for those tips as he had them on his Apterix before Billy had them on the USA-1.

Later - Bob

Here is Jerry Worth when his now called Apterix showed up at the 68 Olathe Nats.  Also a picture of that airplane with the the matching tool box.  Jerry was a serious contender for the best airplane/tool box combination.  That was serious business back in the day.  Had to have white pants and shoes to be in that of thing.

The influence of the Worth Apterix on the Werwage USA 1 is clear.  I am not sure of the exact time lines for these two airplanes.  The picture of Jerry Worth and his airplane is from the 68 Olathe Nats where he was third.  Werwage was there at that 68 Nats with a "40" powered large Ares.  Werwage first appeared on the Nationals scene with his USA 1 at the 70 Chicago Nats where he placed third and then went on to win the World Championships a month later with that airplane.

Keith

[Brett Buck]

Here is Jerry Worth when his now called Apterix showed up at the 68 Olathe Nats.  Also a picture of that airplane with the the matching tool box.  Jerry was a serious contender for the best airplane/tool box combination.  That was serious business back in the day.  Had to have white pants and shoes to be in that of thing.

  Indeed!







Brett

[M Spencer]

Formular 1 grand prix finally produced something usefull ! a sketch ( cartoon - joke ) matching my infinate endplate mulplicity vortices !  in the Numper 1 top notch aer twerp ( oops ) Biography .

Endplates on endplates on endplates .  Dunno how the thingo below would go , on the ends of the wings . Be a start for a chop & cut TESt set up ? .



As the force is side on to the 'mainplane 'primarilly , Itd work similarly . However that is .   

While we're at it , The ' DUCTED '  Endplate would have to have similarities to the Benguine  'Thru Flow'  Tips . Id think 3/16 or 1/4 less 'bore 'than entry might do something right ,
or just a plain 3/16 dia. entry lip . I doubt youd want it to sharp ? . lip stall / breakaway / . Youd think the flow through would generate a bit of stabilty , perhaps .



these F1 things are ludicristly overregulated dimensionally & layout wise , for a carbon fibre coffin in a hyper go cart . 

[M Spencer]

APPARENTLY HALF THE AIRS INVISABLE ! . 



Back to reality !  AND thnks for the Thunderchief Photos , Bob . Much Appreciated .   



Done a Minor amount of faffing around with Venturie type arrangements in the 'Dog House 'on the P-51 & Hurricane , Dropping the opening wide - the aft slightly convergeing ,
trying to get low drag and a 'channeled 'airflow wake , from the exit . Figureing a stabilised wake is  in part an anchor rope - steadying bounce in turbulant air . Worth a try , anyway .

BELOW . somebody getting a bit carryed away on a wingtip . More anon .

[Ken Culbertson]

I am considering trying this shape.  Has anybody tried something similar?  Sort of a double Hoerner.  Top & Bottom.  It will either break up the tip vortices or widen them which would be bad.

Ken

[Dave_Trible]

Ken that looks neat!  Let us know.  The only thing I see from your sketch is that you have some 'normal' tip beyond your upturned winglet.  I'd think this would re-create what you'd hope to minimize in vortices.  Still, it looks like something to try.

Dave

[Ken Culbertson]

Ken that looks neat!  Let us know.  The only thing I see from your sketch is that you have some 'normal' tip beyond your upturned winglet.  I'd think this would re-create what you'd hope to minimize in vortices.  Still, it looks like something to try.

Dave

I agree but they should be smaller.  I wonder how it would work if the forward part of the fence was curved some.  That would allow putting it on the tip.  Food for thought.  We need to get rid of all of this wind so I can fly some and stop doodling.
Ken

[Dave_Trible]

Yes tell me about it.  I mowed the flying field Wednesday.  I bet if I’d have turned the mower into the wind and gone a little faster.....

Dave

[M Spencer]

I think the ' if it looks right , etc etc . ' . That dont look bad .

Been thinking on ' Tube Tips ' ( flow through . )  !

One could do a 1/32 balsa tube , Double inner , triple outer edge . Rolled / moulded ( laminated ) .

IF the wing sheeting was left over the end ( LE , TE , & front etc ) , and about a inch past the end rib , was say 1 3/4 deep -

The Triple half would be that depth / diameter . ( inner bore at 1/16 would be plenty , and gives a edge to catch along the join ) .

SO We get a dowel with sandpaper , & fore & aft sand the LE / TE / sheeting , to match the ia. of the inner tip O.D. 
Cut the sheet at max depth ( spar ? ) to catch the centerline - fore & aft - ( Thickness joint line - outer tip butts there ) .

SO theres a 1 3/4 tube strung chordwise at the tip .! ( Bit like a drop tank ) .We might chuck a flat 1/5 or 1/4 chord edge on in the front to reinforce .
maybe a 1/3 or 1/4 chord long flat divider / brace aft . If we got vetical splitters in aft ( of the spar ) fdlaps to the divider / outer fixed ) 

THEN !  We Sand spanwise to trim the toob to Airfoil section . looking end on at the wing end ( SPANWISE ) wich gets big cutaways , fore & aft. Top & bottom  .

 

Toob on enda wing . flat reinforcer - 1 32/ply front & rear - sanded to airfoil ( 60 wt paper first )This'd leave it full diameter just around the high point . the top & bottom'd be GONE
progressively ( fore & aft ) but the TUBE viewed from out past the wing end , would match the AIRFOIL .

Its actually pretty basic. Cant get a sketch on with the new fangled wotsit 5 thingo from the phone camera . Or I would .

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

summerise !

Tube same depth as wing across end . Sanded to match - viewed end ( of wing ) on .

Throw in a flat thing front & back to stop it getting stoved in . Maybe throw vertical things like Ken's - at tube centerline , Same depth from spars aft to te . Styled .

VIEWD from THE TOP , youd have a long half ellipse missing - Vee - . Wide at entry & exit .

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

this'd be a DUCT , flow through , but ' aerobating , the big wide missing bits 'd GRAB & direct aft AIRFLOW . To do something. usefull. We Hope .

( the ENDS of the tube would match the front wing line & aft rear flap line . IF the vertical aft director was in , seems a good place for the wing flap end . Perhaps . )

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

If zer ving was as fick as der tank diameter !, and yer sanding block is used across the span . End on they wouldnt stick up ( or down ) but a Vert. Spliter @ bore Cr. could ! .



it'd be sanded OFF to wing edge line . Full tube left only at where he has a C.G. symbol . ! so needs a few flat things to brace the ends - Flow'd be better if these were shortish .proportionate . 

( Vertical Splitter AFT from High Pont , could be Vee'd from outer start at sparpoint to full ht. say 3/4 chord . so as its only Stabilising it ( Air crosswise ) toward the EXIT . Better distribution .* )  

* Rectangle on its side . Vertical . Tube dia. hight .  Vee on its side cuttaway devider . Prongs at sparpoint , full depth toward T E . ( Vertical Air Exit guide - and flash looking fin thing / fence ) .  

[John Carrodus]

Air Minister.
The verbal vortex created by your sermon has me in a flat spin. Really interesting but I'm having trouble seeing it in my minds eye. More pictures please.

[Gerald Arana]

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx



xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx


Waaaaaay tooooo much trouble for me! 

Jerry

PS: Besides, I like the ">" tips.

[M Spencer]

Er . . .

might be more easilly decribed , as - say you had a foam wing - Bored a hole fore & aft through the end - and sanded outside edge to 1/8 thick .
and put a flat bit of ply a few inches long, flat spanwise ,  across the front and rear .

If you got really carried away youd put a vertical thing in the center , aft . maybe rectangular .


This'd scare the neighbours at least , and you could confuse them for hours , or weeks even , telling them how it works . 

[M Spencer]

First Thought were TUBES at the ends of the WING . ( as a tip ) unmutilated .



But , if we get carried away .    One of these or suchlike , in a  l o n g tube , stuck along ( into ) the end of the wing .

--------------------------------------------------------------------------------------------------------------------------------------------------------------------

BUt , as we're up & downing , a bit of The Wing Flap , going through it , would be a bit VANE ish .



oops ! . ( next we could have a hollow wing , ' blown ' flaps central    at rear of the slot . 

RIGHT ! , Say the WING was as thick as the JET TUBES , and you sanded off the tubes . It'd leave a bit of a



in the Top & Bottom , In front & behind the high point . A brace across the front ( L E ) one at the rear . Maybe moving as a flap extension .
( Fixed part in front of flap . ( Both these are in the same PLANE as the flap . On Center Horizontal ) Maybe a vertical flow guide aft . Cruciform .

[M Spencer]

THIS sorta illustrates IT . ( Cept theyre NOT at the TIPS ! ) ( or carved away to parabolas in the wing surface ) ( Corse , you can leave wotever of the tube across the tip you like -
just occured to me a surface entry and exit might more suit our aerobatic airflow requirements - though its still looking from dead ahead - a tube the same thickness as the wing ,
Stuck on the end .

Just that you might carve of the protrubances outside the airfoil ( RIB ) as not particularly appropriate ! 



Tubes on the END , not in the middle , as here . ( illustrates tubes as thick as the wing . )

[M Spencer]

Oh Dear v!



Likely better device is tube , wing thickness . FRONT flat devider / outer surfaces removed ( Could carve a angle from inner front to outer at high point )
With Flap across rear exit . ( Full Dia. Exit ? ) Variations & derivatives ! . ( illustrates tube intersecting airfoil )



The DUCT should stabilise flow out there , and could be vectored by the flap end . Throwing a cardboard tube on the end of a wing with duct tape ( with leadout slots )
would be a cheap start . Bring the nail scissors along to the field . And superglue & balsa / ply scaps .

This . Full Circle . On the end of a thick ( our stunt ) wing . I.E. 1 3/4 tube on the Avg .46  wintip .

[M Spencer]

Before we got sidetracked .





Now , If you continued the flaps out on them .         

[John Carrodus]

Air Minister
Many thanks , all those pics and illustrations- much clearer.

Considering most of the devices shown are operating in air rushing past, through and around at approx 10 x our typical stunt ship speeds, I wonder how useful they really are.

Having said that- in my earlier gliding days I got to fly ( spelling might be crook here) a Rhonelerker. The thing flew like a brick, made from canvas and steel tubing, the wing was half a metre thick and it looked like a Zeppelin. At the speeds we managed to squeeze out of that old crate, a fancy wingtip vortex device from a 737 Max would have made little to no difference, but then I guess that's what we are talking about at competition level.

[M Spencer]

NOW Im woncering if , say a tube ( Entry at existing flat tip ) cut so angle finishes at the highpoint , more or lesss , Flattened as it goes aft to the T E , so it flares out ( in plan )

but feeds aflat discharge - continuation of T E line . maybe 5 or 6 mm deep , would dispose of the vortex . The pressurised air should  be faster than the airspeeed ?
This could do something . One way to find out .

Considering most of the devices shown are operating in air rushing past, through and around at approx 10 x our typical stunt ship speeds, I wonder how useful they really are.

cording to Berringer , 5.0 is 94 Kph .

If you try sticking your arm straight out the window ( open it first  )  Hold your hand FLAT then try it vertical , and open & close your fingers .

Folkerts Id hopped a lift , in the sticks , to the field . Back of a flat deck . Was about 70 maybe 80 Kph on the big straight ( wobbly weavy chip seal )
So of course ,  ' we ' held the plane by the fuse landing gear in a firm grip , up in the airflow over the cab roof . Used a finger on the other hand to
carefully push the FLAP trailing edge down . The plane very firmly ( 50 Lb's ! ? ) pulled the big strong hairy builders arm UP . Quickly desisted .
As a corner was comming up , bumpy & weavy chipseal , further experiments were discontinued . But if you have a Van or Car with a Sunroof ,
by all means , go ahead ! . 

VORTICES from the TIPS , the Phantm with the 45 to vertical weaved in strong variable steady wind . ( yawed ) 15 to 20 mph  wind .
Putting mere 1/8 sheet extensions on the upper surface from the highpoint aft , going outward , cured that . Triming to about 1/4 flare out ,
got the turn something like even . Id started at maybe 1 in wider at the rear .

Strong wind multiplies the forces & makes the effects perhaps more redily evidant . If it gives it more consistant line tension  and stops it weaving ( yaw )
and bobbing about , it increases the pilot confidance & daring . 

Id say cleaning up the flow out there can get the bottoms more consistant , and placement , intersections etc , when the things operating steadyer
rather than being rocked and bounced . Where its more of a lottery to catch ainitial turning point . Same as got solid controls . Keeps it ' on course ' .

So , well throw a picture of the last tarted up Phantom here , so you can glare at the tips , These have it feeling like its got a few inches more span each side .

Incidently , the P51 bare wood photo , id simplified them as Id thought they were ' locking in ' to much . It turned out to be the overlight horns Id been supplied .
Even though It had a 3/32 wire to each flap , the detempering meant it didnt want to pull into the vertical ofr level , in a strong wind . Where others were disturbed .
Tho Id got the worst air . Butchery to put in custom 1/8 horns cured that , though didnt improove the looks . Pity I prematurely de  sophistified the concave tip undersurfaces .

[M Spencer]

Poor photo , but you can get a good idea of the shape of the underside of the tip , in the side view . This definately worked as if it had ' more wing ' .



Again , a poor photo . But if you look close , you can see the wing end is a plain 45 Degree canted rib . This is the second I built . And first tried the the further tip extensions on .



As it burned about 10 gallons in the FSR 25 , generally on 55 ft of .018 wire , in all weather ( it was intresting in 30 Kt. But regularly in 15 to 20 & often in 25 . Flying on Avg. every other day for a year . On the Coast . )
Originally a 21-35 ST , a 21/40 , OS 35 S , ST 35 C then a 21/46, whereabouts the nose cryed enough . Renosed and fluked a decent power set up with the FSR 25 clone ( magnum with Fox 25 BB intake ) The Taipan
Needle rattled in the spraybar . Burble Run . Touch needle to reset a click , it'd smooth out . Immediate re burbbly on release . Figure like a weber atomiser tube , it bas pre atomised . Sealing the NVA with fuel tube
sealing the needle ruined the run . Spraybar outboard of tank , it was full rich level , and full lean over the top . Tank vent out the side cut at 45 deg . Strong Wind It'd yaw up & down wind .

The Tip Extensions reduced that 75 % easy . didnt get around to making the Vert Stab smaller to better balance the side area , untill the later blue one .

As Ive said , zillions of flights on it in all weather , so if a definate performance change came about ( like after hoseing the sand from the field out of the fuse when I decked it inverted one time -
and the water went under the wing . Big Shake to get most out , the a few days later ( still being flown ) a week in the car in the sun almost got it back to weight . The second week did .

Performance was rather soggy with 8 or 10 ounces of water absorbed in the wood . Usually flown agro after Id got back fom town . Dosnt work . Accurate timing & delicate control is reqd. with it .
Or you run,like stink to regain line tension . The Rear Tip outer extensions to the 45 canted tip definately improoved controlability & accuracy of entry & squares , tho more concentartion s lightly
 Reqd. in rounds when its blowing like stink , to conter the ' egging ' from the extra grip from the enhanced smoothness / reduced jumpyness & reduced lateral weave from reduced vortices . 

[M Spencer]

This is about the SPEED we fly at , F2B . 55 mph , anyway . If the plane was stationary ( like on the back of the ute ! ) this is what you get . In rough air .



Actually flew in a cyclone / hurricane once . Where the air came off the hills - over the harbour - rose - and funneled through the gap in the hedge we hid behind to launch .
Hold on like grim death , catch a lull , and crouch & get over quick . Mightve been funneling 90 at times through there . Tail Wind . 1.2 laps on a streamlined tweaked G 15 FI
combat wing . @ 52'6 of .015 solids .

Lulls were shorts , attempts at loops , overhead it could cut loose . SPRINT downwind and tease lines tight , so as they wouldnt break .Brother refused to launch it a third time
for some reason .
Club meeting " Been flying lately Mat " ?  Yea Sunday , created a general foofaroor of dersision & unbelieve . As it'd been blowing on a overlap HARd for two weeks .
Parently was 1972 . Whadderyer spect offa 12 Yr Old !  Already had 4 years of dealing with weather , contro line . Bought fuel in 4 imp gal . First time it was FREE .
Next $ 2.50 for the can ! Then standardised at $ 4 for 4 Imp. Gal. can . DOPE was $ thirty for the same 4 gallons  . 320 ounces . Paper runs & milk runs paid for it all.
jogging with mik crates each evening, three youd hold the top one with your chin .  meant you had a fair turn of speed , unladen . Not to mention evadeing hoodlums .