Author Topic: Double flap horn setup question. Update! (Read 11496 times)

Avaiojet · « **on:** October 03, 2014, 02:47:54 PM »

I have this wing, has a Ringmaster type TE that is swept forward.

Two flap hornes are needed.

I'd like to see how others set up their pushrod to the flap hornes. I'm hoping for photos.

Thanks in advance.

Charles

Tim Wescott · « **Reply #1 on:** October 03, 2014, 02:53:37 PM »

Search on "lucky box". You should find useful articles.

Avaiojet · « **Reply #2 on:** October 03, 2014, 03:01:09 PM »

Quote from: Tim Wescott on October 03, 2014, 02:53:37 PM

Search on "lucky box". You should find useful articles.

Tim,

I have some "lucky boxes"

Is this the use for them?

You would think they would wear inside and get loose or sloppy?

Tim Wescott · « **Reply #3 on:** October 03, 2014, 04:13:14 PM »

The last time I built a plane with a lucky box, the lucky box did not wear out.

Of course, I was still flying beginner, and crashing all the time...

If wear is a concern, then consider making them out of 1/32" phenolic, epoxy-glass, or aluminum.

Avaiojet · « **Reply #4 on:** October 03, 2014, 04:40:57 PM »

Tim,

Thanks for that reply.

I was really considering two control horns.

With two pushrods off the bellcrank.

I'll set it up and see how it reacts.

Tim Wescott · « **Reply #5 on:** October 03, 2014, 04:48:14 PM »

Quote from: Avaiojet on October 03, 2014, 04:40:57 PM

Tim,

Thanks for that reply.

I was really considering two control horns.

With two pushrods off the bellcrank.

I'll set it up and see how it reacts.

The problem with that is that, because the bellcrank and the flap horns operate in different planes, the flaps won't be actuated quite the same. This will result in a bit of rolling with flap movement.

It may not matter -- particularly because you can use the excuse that I used several years ago, which is you won't fly well enough to notice! But it won't be "right".

There's fancy ways to do linkages with idler bellcranks and whatnot -- but that adds complexity, more oddball geometry, and weight. Which is probably why the lucky box was invented.

Avaiojet · « **Reply #6 on:** October 03, 2014, 06:24:45 PM »

I would like to know more about those other possibilities?

Charles

Paul Smith · « **Reply #7 on:** October 03, 2014, 06:35:12 PM »

Make an X-crank with two output arms on opposite sides. Each side drives one flap. In my opinion the "lucky box" might work for slight misalignment, but not on the order of a Ringmaster.

Avaiojet · « **Reply #8 on:** October 03, 2014, 06:46:46 PM »

Quote from: Paul Smith on October 03, 2014, 06:35:12 PM

Make an X-crank with two output arms on opposite sides. Each side drives one flap. In my opinion the "lucky box" might work for slight misalignment, but not on the order of a Ringmaster.

Paul,

Thanks for the reply.

I thought about the "X" bellcrank, was not sure if I have the room and I'd be concerned with the lead outs getting in the way. Plus, one horn would have to be "under" and I don't have the room in the underbelly. At least I don't think I do?

I never was one to install my bellcranks with the pivit arm facing in.

Thanks again for the reply.

Keith Renecle · « **Reply #9 on:** October 03, 2014, 10:26:07 PM »

Hi Charles,
The Crossfire from Bob Hunt has a swept forward TE, so maybe someone that has built one, or has the plans can answer this for you. It seems like many have been built and the plans are available. I still have a Ringmaster Imperial kit to build, and it shows a bent flap horn and that is supposed to do the trick, but that makes very little sense to me.

Keith R

Chris Wilson · « **Reply #10 on:** October 04, 2014, 05:47:22 AM »

Quote from: Avaiojet on October 03, 2014, 02:47:54 PM

Two flap hornes are needed.

Charles

Get a look at the Bob Palmer Thunderbird differential flap system and go from there.

It uses a simple 'Y' shaped pushrod.

Dave_Trible · « **Reply #11 on:** October 04, 2014, 06:17:43 AM »

Charles if you will go to the 'classic' section here and look at my Sterling Spitfire posts you'll find a photo of the method I use for such horns. This gives exact replication of movement on both sides and holds up as well as any other typical hookup. Keep the fork in close to the horns so nothing has space to flex.

Dave

Avaiojet · « **Reply #12 on:** October 04, 2014, 06:42:35 AM »

David,

I followed a bit of that build, I actually had that Spitfire kit but elected to sell it on ebay.

Yes, some of the wood was really heavy and hard.

You did a great job with that model.

I was going to ask you where you purchased the wheels? And what size they were.

I see your flap setup. I like that epoxy idea around the horn wire, I will copy that.

I wanted to use Tom Morris ball ends, which adds a bit of complexity to my system.

Chris,

I actually built the Palmer T-Bird, but it was so long ago I can't remember the linkage.

Thanks for the replies

Dave_Trible · « **Reply #13 on:** October 04, 2014, 06:51:18 AM »

Charles I got those wheels from the Tom Morris road show. Really light and narrow. 2 1/4" I think. Your ball links could be set up about the same way. If you are using them for adjustment reasons you could hook up the flaps like this ( without links) and the rear pushrod with the links and still get the adjustment capability between flaps and elevator. Not much reason to adjust the forward rod.

Dave

Avaiojet · « **Reply #14 on:** October 04, 2014, 07:59:35 AM »

Quote from: Dave_Trible on October 04, 2014, 06:51:18 AM

Charles I got those wheels from the Tom Morris road show. Really light and narrow. 2 1/4" I think. Your ball links could be set up about the same way. If you are using them for adjustment reasons you could hook up the flaps like this ( without links) and the rear pushrod with the links and still get the adjustment capability between flaps and elevator. Not much reason to adjust the forward rod.

Dave

Dave,

I'm not sure how to set the two ball links up on one rod? Wire and solder? That's why I was going to use two rods off the ballceank, one under the other and both with ball links.

Your setup, what did you have under the cloth and epoxy, to keep it off the horn wire?

Dave_Trible · « **Reply #15 on:** October 04, 2014, 08:22:13 AM »

The wire turns in brass tubing under the cloth. You 'd still have to keep the ball links set up on a fork close to the horn lest flexing ruin the whole project. That and accumulated flex and slop is exactly why I'd nix the double rod concept. I'm afraid this is one of those things being way over thought for what is needed. I wouldn't make it any more complicated than it has to be. In practice you'll need less than 30 degrees of travel and equal deflection. I would use the most simple way to that end.

Dave

Trostle · « **Reply #16 on:** October 04, 2014, 11:47:09 AM »

On a Ringmaster or other similar sport ships, a double horn arrangement MAY be suitable. But, it is advisable to not use a double horn arrangement. As already has been suggested, unless special provisions are made, there will be asymmetric flap deflection due to the position of the bellcrank and the horns. But the main problem with split horns is that there will be too much flex between the horns and will result in trim problems that will be almost impossible to adjust as the loads on one flap are different than on the other during the maneuvers so the flaps will deflect/twist in an unbalanced manner. The airplane will tend to roll in ways during the pattern that just cannot be trimmed to fix. I would never use a split horn arrangement on a model built for competition stunt.

Lucky boxes solve the problem here.

Also, unless there is a large amount of hinge line sweep and/or dihedral, it is surprising that a single horn will suffice and will operate quite satisfactorily without any binding during the flap movement. My Rabe Bearcat has performed well for a few years with a single flap horn. The design has about 5 degrees of dihedral and the flaps are swept forward about 2 degrees. There is a limit for how much angular difference there can be in the hinge line angle. Based on what I just found on a scale application where there is 12 degrees dihedral in the horizontal tail, a lucky box was required. I would estimate that the angular difference in hinge lines for this limit before a lucky box is required would be around 6 to 8 degrees combined dihedral/hinge line sweep.

If the right material is used for the lucky boxes, wear will not be a problem. There is not that much relative motion between the horn and the lucky box material.

Keith

Avaiojet · « **Reply #17 on:** October 04, 2014, 12:33:06 PM »

Dave.

I think you're right, overthinking can create more issues than the project is worth. Ask me how I know?

I did notice, that the space between the horn closes when the horns are moved forward. Considerable.

I'm using 1/8" wire, not sure if 3/32 is preferred?

I'm using a flap horn with 1" height on the flaps, down to .75" in height on the flap horn to .75" in height on the elevator horn. Fixed with no adjustment. Three in bellcrank.

I think I have a solution to having this operate with ball links on all ends, six total when using two bellcrank rods.

A bit crowded on the two flap horns, but nothing touches with the 3/4" bellcrank movement in both directions.

The extra grams will pronably be worth the smoothness over a period of time?

Kieth,

Thanks for the reply.

I just saw your reply after I posted this for Dave.

I would have to check the angle of the TE.

I'll get a photo of my progress. Take a few minutes.

Avaiojet · « **Reply #18 on:** October 04, 2014, 01:10:40 PM »

OK, here's what I currently have.

Angle is 20 degrees, TE has 10 degrees on each side.

Photo tells most of the story.

Yellow tape is temporary. Rods will be replaced with CF rods.

Flaps in up or down position are the same, that is, I have the same movement and degrees in both flaps. One does not move more than the other through the complete cycle, forward and aft.

As I said, I only have .75" forward and aft movement on the 3" bellcrank..

Cramped because the fuselage isn't wide in that area but nothing touches.

Dave_Trible · « **Reply #19 on:** October 04, 2014, 01:58:46 PM »

The horns should work OK. Still like to see one single source pushrod driving both horns though. Of course lucky boxes would be fine too-use them for the flaps on my take-apart airplanes with no issues.
Dave

Avaiojet · « **Reply #20 on:** October 04, 2014, 02:15:24 PM »

Quote from: Dave_Trible on October 04, 2014, 01:58:46 PM

The horns should work OK. Still like to see one single source pushrod driving both horns though. Of course lucky boxes would be fine too-use them for the flaps on my take-apart airplanes with no issues.
Dave

Dave,

I would like one pushrod also. It's not rulled out.

I thought I had "lucky boxes." What I have is hard wood flap ends. If that's what you call them?

Dave_Trible · « **Reply #21 on:** October 04, 2014, 02:32:36 PM »

They may be if slotted to allow the horn wire to move laterally a little as required. I make mine from layered plywood and epoxy.

Dave

Randy Cuberly · « **Reply #22 on:** October 04, 2014, 05:33:44 PM »

I think "Lucky Boxes" are by far the best solution for this kind of problem. I Use them often and assemble the boxes separate from the flap using 1/16 thick G-10 material, with 1/8 inch plywood about 3/16 inch wide on each side of the horn area (for 1/8 inch wire horns), then balsa sheet layered on each of the G10 to make up the thickness of the flap. Inset and glue into the flap with epoxy and sand both sides to match the flap.
Even with 10 degrees forward slope on the trailing edge you only need about 3/32 clearance on each side of the horn wire to more than accomodate the horn movement, (Actually less than this but I use 3/32 to also allow for a tad of misalignment).
The G10 gives less friction than plywood and is more resistant to wear. They work slick and I've never seen one fail.
This is far less complicated than a double horn arrangement, especially with two pushrods (not a good idea at all in my opinion)

Randy Cuberly

Avaiojet · « **Reply #23 on:** October 04, 2014, 05:44:09 PM »

Randy,

Thanks for the reply and info.

G-10 is fiberglass sheet.

.060 at 8.00 for a 12 x 12.

Is this how you buy it?

From your explanation of material, I'd have to have a flap at least .675" thick

I'm guessing I have to cut a "straight" area at my TE for a normal horn and bent wire setup. Obviously?

I'll search for a photo of a lucky box.

Photo anyone?

P.S.

I did find this.

http://stunthanger.com/smf/index.php/topic,22743.0.html

Dave_Trible · « **Reply #24 on:** October 04, 2014, 06:29:30 PM »

Lucky boxes on Desperado...

Avaiojet · « **Reply #25 on:** October 04, 2014, 07:05:27 PM »

Quote from: Dave_Trible on October 04, 2014, 06:29:30 PM

Lucky boxes on Desperado...

Dave,

Thanks for that photo.

Your workmanship is nice. I can tell you pay attention to detail.

Is the TE swept forward on your model?

Dave_Trible · « **Reply #26 on:** October 04, 2014, 07:38:44 PM »

No Charles it's straight. The lucky boxes are just to allow the flaps to be plugged in during assembly since the horn is mounted in the fuse.

Dave

Avaiojet · « **Reply #27 on:** October 04, 2014, 07:47:41 PM »

Quote from: Dave_Trible on October 04, 2014, 07:38:44 PM

No Charles it's straight. The lucky boxes are just to allow the flaps to be plugged in during assembly since the horn is mounted in the fuse.

Dave

Dave,

Take apart! I seen Marcus' build on his take apart.

That is really a tremendous amount of work. Are there many modelers building take apart stunt ships?

Dave_Trible · « **Reply #28 on:** October 04, 2014, 08:34:16 PM »

I would guess mostly those thinking WCs!!!

Dave

Tim Wescott · « **Reply #29 on:** October 04, 2014, 08:38:41 PM »

Quote from: Paul Smith on October 03, 2014, 06:35:12 PM

In my opinion the "lucky box" might work for slight misalignment, but not on the order of a Ringmaster.

Are we talking about the same mechanism? The application I was talking about was a V tail with a dihedral angle of around 40 degrees. The lucky boxes were built with plain old 1/32" plywood, and they worked great.

Trostle · « **Reply #30 on:** October 04, 2014, 08:55:21 PM »

Quote from: Tim Wescott on October 04, 2014, 08:38:41 PM

Are we talking about the same mechanism? The application I was talking about was a V tail with a dihedral angle of around 40 degrees. The lucky boxes were built with plain old 1/32" plywood, and they worked great.

I built a Swee Pea from S. Calhoun Smith plans (Mechanics Illustrated June 1948) with the V-tail that has 40 degrees dihedral on each side of the stabilizer. One control horn, lucky boxes, and the controls are absolutely free and no more "slop" than with a regular horn/pushrod set up.

Keith

Mike Keville · « **Reply #31 on:** October 04, 2014, 09:17:49 PM »

Back in '08 I built a little 1/2A profile scale A-26 (Pat King design) which has a somewhat v-dihedral'd stab/elev. Completely ignorant of how to make this work - despite more than 60 years of modeling at the time - I asked Keith how to do it. He tutored me on "Lucky Boxes", which I then ordered from RSM (plywood pieces). Bingo! No hassle...no binding...worked very well.

By the way, Keith's 'Swee Pea' is a work of art. A bit small for OTS, it might become a good Scale entry.

Randy Cuberly · « **Reply #32 on:** October 04, 2014, 10:06:19 PM »

Quote from: Avaiojet on October 04, 2014, 05:44:09 PM

Randy,

Thanks for the reply and info.

G-10 is fiberglass sheet.

.060 at 8.00 for a 12 x 12.

Is this how you buy it?

From your explanation of material, I'd have to have a flap at least .675" thick

I'm guessing I have to cut a "straight" area at my TE for a normal horn and bent wire setup. Obviously?

I'll search for a photo of a lucky box.

Photo anyone?

P.S.

I did find this.

http://stunthanger.com/smf/index.php/topic,22743.0.html

Charles,
NO! .060 + .060 + .125 = .245 ( less than 1/4 inch) + .031 + .031 = .307 (less than 5/16). In this case use two pieces of 3/32 balsa and sand it flush on both sides of the flap. (it's just filler).

If you're using 3/32 wire (which I don't recommend) then you use 3/32 plywood and you have:
.060 + .060 + .094 = .214 (less than 1/4 inch again) +.031 +.031 = .276 (less than 5/16 again) Fill this the same way and sand it flush.

For flaps on stunters I typically use 5/16 thick flaps or sometimes 3/8. Thin flaps flex and cause a plethora of trim problems.

Randy Cuberly

Chris Wilson · « **Reply #33 on:** October 04, 2014, 11:59:18 PM »

Charlie,
if you are stuck on using 2 horns then perhaps you could not drive them back from the bell crank as it can get very cramped.
Instead have may have one long drive rod from bell crank to tail and AFT of flap hinge line make a take off point from that rod for the 'Y' shaped twin drive rod forward to the flap horns.

In other words the flap drive rods drive forwards to the horns and not backwards.

Avaiojet · « **Reply #34 on:** October 05, 2014, 05:12:21 PM »

Well, to put the matter of two hornes to rest.

First I would like to thank everyone for their replies, advice and interest.

Here's what I decided and why.

I decided on two CF pushrods and ball links on all ends.

Few reasons for this. The main reason is I didn't have material to make lucky boxes and I did want to close the wing up today.

Another reason is I have no experience with lucky boxes.

I do however, have some experience with CF pushrods and ball links.

Yes, setting this up killed me. I had differential movement no matter how I adjusted these horns.

I finally realized that both horns had to be the "exact" height and the two pushrods "exactly" the same length.

Also, the bolt on the bellcrank arm had to be dead center. I moved the bellcrank three times.

I tweeked the height of the horns by bending them a tad till both horn rods were perfect in their travel.

I did get it done and I'm really happy with how they operate, really smooth.

Thanks again to all those modelers that replied.

You know I appreciate it.

Dick Pacini · « **Reply #35 on:** October 05, 2014, 06:28:09 PM »

That looks like a lot of unnecessary weight.

Avaiojet · « **Reply #36 on:** October 05, 2014, 06:31:22 PM »

Quote from: Dick Pacini on October 05, 2014, 06:28:09 PM

That looks like a lot of unnecessary weight.

The rest of the model is light.

Sean McEntee · « **Reply #37 on:** October 05, 2014, 07:27:32 PM »

I know it's far too late for this question... But why are we putting flaps on a ringmaster?

Avaiojet · « **Reply #38 on:** October 05, 2014, 08:04:19 PM »

Quote from: Dick Pacini on October 05, 2014, 06:28:09 PM

That looks like a lot of unnecessary weight.

Dick,

I just weighed the wing.

10.4 oz. 54" in span. Totally framed, only needs covering. Still have some shaping to do to the LE and cut down the center sheeting. Might loose a .5 oz there.

CF rods are light, only extra HDWE is the extra CF rod, and a bit more horn rod.

Gotta decide if the gear will be in the fuse or wing. Heavier if I go with gear in the wing.

Has to be gear someplace.

There's another Thread where I have the weights of the parts.

Sean,

Thanks for the reply.

It's not a Ringmaster. It's my own design, scratch built.

Sean McEntee · « **Reply #39 on:** October 05, 2014, 10:04:20 PM »

K gotcha

Clint Ormosen · « **Reply #40 on:** October 05, 2014, 10:33:52 PM »

So, another thread from Chuck asking for advice then poo pooing on everyone's suggestions and doing the job some retarded way that doesn't work as well and weighs twice as much. Typical.

Randy Cuberly · « **Reply #41 on:** October 06, 2014, 12:07:39 AM »

Quote from: Clint Ormosen on October 05, 2014, 10:33:52 PM

So, another thread from Chuck asking for advice then poo pooing on everyone's suggestions and doing the job some retarded way that doesn't work as well and weighs twice as much. Typical.

Yeah,
Total waste of time. You'd think we would learn. I actually thought for a few minutes we were accomplishing something...Silly Me!

Last time for me!

Randy C.

Chris Wilson · « **Reply #42 on:** October 06, 2014, 04:24:42 AM »

So where does the elevator pushrod go when the twin flap horns 'lock horns' together?

Does it travel underneath the wing?

Bill Morell · « **Reply #43 on:** October 06, 2014, 05:39:08 AM »

Quote from: Avaiojet on October 05, 2014, 06:31:22 PM

The rest of the model is light.

Well if it isn't you can always drill some holes.....

andrew stokey · « **Reply #44 on:** October 06, 2014, 08:06:00 AM »

Clint,
Are U on some kind of crusade or what.? Give it a rest. If U don't agree just.....shutup

Avaiojet · « **Reply #45 on:** October 06, 2014, 08:35:54 AM »

Quote from: Chris Wilson on October 06, 2014, 04:24:42 AM

So where does the elevator pushrod go when the twin flap horns 'lock horns' together?

Does it travel underneath the wing?

Chris,

Elevator horn ball link attaches to the right side of the right horn under the flap ball link. I had it in place. Touches nothing in it's movement.

Now for those that believe you've been Poo Pooed.

If you read my original Post, you can clearly see my thoughts were with "Two Pushrods."

Lucky boxes. I explained I know nothing about them and that's why I decided to not use them. Plus, they would have offered friction then possibly play over a period of time. AND they cannot be serviced.

I can service both those horns and HDWE from removal of the canopy if I elect to have a removable canopy.

Sure, there were many great suggestions and I said I appreciate the offerings.

So, again, thank you for your suggestions and replies, but I feel I made the best decision for this model and my experience.

Remember, I said I have no experience with lucky boxes.

Dan McEntee · « **Reply #46 on:** October 06, 2014, 10:51:21 AM »

Quote from: Avaiojet on October 06, 2014, 08:35:54 AM

Chris,

Elevator horn ball link attaches to the right side of the right horn under the flap ball link. I had it in place. Touches nothing in it's movement.

Now for those that believe you've been Poo Pooed.

If you read my original Post, you can clearly see my thoughts were with "Two Pushrods."

Lucky boxes. I explained I know nothing about them and that's why I decided to not use them. Plus, they would have offered friction then possibly play over a period of time. AND they cannot be serviced.

I can service both those horns and HDWE from removal of the canopy if I elect to have a removable canopy.

Sure, there were many great suggestions and I said I appreciate the offerings.

So, again, thank you for your suggestions and replies, but I feel I made the best decision for this model and my experience.

Remember, I said I have no experience with lucky boxes.

So in other words, you never had any intention of doing this any other way, you just wanted to show us all how it's done in your world? People took the time and trouble to provide the information that will help your project, if you just wanted to show off, why ask for suggestions?
Several of the best builders and fliers in the country have pointed out in detail how to do this, and there are numerous other threads with even further detail. Makes me wonder about your reading comprehension skills. I can't believe you are really worried about friction and wear and "servicing the lucky boxes." This model will never be finished, so why worry about what will never happen?
And so it goes.
Dan McEntee

Brett Buck · « **Reply #47 on:** October 06, 2014, 11:03:55 AM »

Quote from: andrew stokey on October 06, 2014, 08:06:00 AM

Are U on some kind of crusade or what.? Give it a rest. If U don't agree just.....shutup

Nice. Some guy - Charles - repeatedly jerks people around, takes advantage of them, admits he is jerking everybody around, and if anyone objects, they have no right to object whatsoever. Interesting sense of values you have there. Next I am sure you will be running back to Sparky or the other mods for protection from all those mean people on the internet.

Brett

Brett Buck · « **Reply #48 on:** October 06, 2014, 11:07:36 AM »

Quote from: Dan McEntee on October 06, 2014, 10:51:21 AM

So in other words, you never had any intention of doing this any other way, you just wanted to show us all how it's done in your world? People took the time and trouble to provide the information that will help your project, if you just wanted to show off, why ask for suggestions?

The best part is that this idea, while sound enough, has a fatal flaw in the implementation that will become evident at some point. But since the internet White Knights decided we can't argue with Charles, I guess he will find out the hard way later - in the unlikely event he ever completes this and tried to fly it.

Brett

p.s. the fatal flaw IS NOT the fact that he put the ball links on the wrong side of one of the horns. Although that is a flaw, too, that made it much more difficult than it would otherwise have been. That's why the uprights are bent strangely.

Randy Cuberly · « **Reply #49 on:** October 06, 2014, 11:14:18 AM »

Quote from: Brett Buck on October 06, 2014, 11:07:36 AM

The best part is that this idea, while sound enough, has a fatal flaw in the implementation that will become evident at some point. But since the internet White Knights decided we can't argue with Charles, I guess he will find out the hard way later - in the unlikely event he ever completes this and tried to fly it.

Brett

p.s. the fatal flaw IS NOT the fact that he put the ball links on the wrong side of one of the horns. Although that is a flaw, too, that made it much more difficult than it would otherwise have been. That's why the uprights are bent strangely.

Quite right Brett, but I wouldn't tell him about it for a hundred dollars!!

Randy C.