stunthanger.com
General control line discussion => Open Forum => Topic started by: Mike Griffin on June 30, 2022, 03:54:13 PM
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I do not understand the purpose of this on a CL Model.
Mike
https://www.facebook.com/groups/119490068110977/permalink/5490529601006970/
Mike
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Seems like way too much flap but it looks cool. Some guys just like to do things the most complicated way they can just for the fun of it.
Best, DennisT
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I do not understand the purpose of this on a CL Model.
Mike
https://www.facebook.com/groups/119490068110977/permalink/5490529601006970/
Mike
Isn't that the wing on a plane called "Velvet"?
Jerry
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That is the wing as per Wesley Dicks' Velvet. Wes has the original in the AMA museum, and several others have built the design with some success.
Wes got the idea from watching airliners fly over with their flaps extended in just that manner. Being a retired engineer, he just had to try it. Also, being a GOOD engineer, he made it work and work well. Wes is from Fort Wayne, Indiana, and still flies a good pattern at the age of at least 90! (He's also great company.) H^^ H^^
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Following up on Will's post:
Here are some pix of the double-slotted flaps Wesley Dick engineered for his Velvet 3: as published in Stunt News and now displayed in the AMA Museum. Wes' mechanism is totally different than the picture in Mike G's facebook link. I do not believe that the design in the facebook post presents 2 tiers of flaps with the slots as Wes' does.
Back to Mike's original question: double slotted flaps hold the promise of a larger increase in lift versus a plain flap but with a smaller drag penalty. Typically, slotted or double slotted flaps deploy in a single direction - as for landing. Wes' innovation was making a double slot mechanism that works in both directions. All the pivots are on span-wise pins. removing a few set screws lets you remove the flaps completely. Of course you can build and finish all the flap segments individually off the wing. His mechanism is also dirt simple and extremely robust - epitome of good engineering design.
I have watched Wes' Velvets 3 & 4 with the double slotted flaps and they outperformed Velvets 1 & 2 with the traditional simple flap. Not scientific, but I know what I saw. Mutual flying buddy Larry Fruits has built a Velvet on which he can switch back & forth between a simple flap and the double slotted flaps. Thus a real back to back comparison cna be made.
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Following up on Will's post:
Here are some pix of the double-slotted flaps Wesley Dick engineered for his Velvet 3: as published in Stunt News and now displayed in the AMA Museum. Wes' mechanism is totally different than the picture in Mike G's facebook link. I do not believe that the design in the facebook post presents 2 tiers of flaps with the slots as Wes' does.
Back to Mike's original question: double slotted flaps hold the promise of a larger increase in lift versus a plain flap but with a smaller drag penalty. Typically, slotted or double slotted flaps deploy in a single direction - as for landing. Wes' innovation was making a double slot mechanism that works in both directions. All the pivots are on span-wise pins. removing a few set screws lets you remove the flaps completely. Of course you can build and finish all the flap segments individually off the wing. His mechanism is also dirt simple and extremely robust - epitome of good engineering design.
I have watched Wes' Velvets 3 & 4 with the double slotted flaps and they outperformed Velvets 1 & 2 with the traditional simple flap. Not scientific, but I know what I saw. Mutual flying buddy Larry Fruits has built a Velvet on which he can switch back & forth between a simple flap and the double slotted flaps. Thus a real back to back comparison cna be made.
Thank you Dennis. I had never seen this before.
Mike
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That is the wing as per Wesley Dicks' Velvet. Wes has the original in the AMA museum, and several others have built the design with some success.
Wes got the idea from watching airliners fly over with their flaps extended in just that manner. Being a retired engineer, he just had to try it. Also, being a GOOD engineer, he made it work and work well. Wes is from Fort Wayne, Indiana, and still flies a good pattern at the age of at least 90! (He's also great company.) H^^ H^^
Thank you Will.
Mike
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I do not understand the purpose of this on a CL Model.
Mike
https://www.facebook.com/groups/119490068110977/permalink/5490529601006970/
Mike
It was a rainey day and nothing was on the telly....
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I wonder how the Paul Walker Trim flow Chart would come into play? Adjusting uneven flaps to achieve level wings would seem a bit challenging.
Steve
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Mike ...... I have build several planes with the configuration shown below. They were, as far as I know, the idea of a fellow Houston flyer Charles Hofacker. He had them on a fairly heavy diesel powered plane and I was impressed by it. I flew it and was amazed at the powerful turn in the tops of hourglasses. We decided to call them Hofflappers.
I made a model of them for my garage wind tunnel. The results are shown below. With a piece of tape over the gap, the flow over the flap separates, but with the gap open to function as a slotted flap, the flap flow is attached and produces more lift. There is some sailing data on similar items.
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The last time you threw one of those crazy configurations out there I ended up with this (see pix). Now I haven't hinged the flaps on this one yet. Are you going to lure me into giving this a try too? It fits everything I believe about flaps. There is a reason most planes flaps are "Fowler" like. What sort of gap at neutral? I suspect it is as close as possible and does the flap need to have an airfoil shape?
Ken
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That’s Funny John Hill says that I deliberately try to lead Dallas into the briar patch. Back awhile, it was Dallas flyers (some not all) that adopted the inboard mounted ST60. Even though my local friends saw how well it performed, they wouldn’t try it. Tom Farmer tried it and numerous Dallas flyers followed suit. I see you’re canard is going to be electric, so you’re off the hook for the inboard ST60, but it’s not too late to try the slotted flaps.
Yes the gap at neutral, just enough for clearance. The flap airfoil shape, mainly the leading edge, is a good question. Roundy but not too blunt.
The real critical point is the hinge offset location. Offset location in relation to the flap leading edge shape. You’d like the optimal gap to occur at about 30 degrees of deflection (I’m guessing here) It seems like the proper offset is about 3/8 to ½ inch. Check out the link below. I think he shows the pivot at about 0.97% of the main wing chord.
http://tspeer.com/RigidRigs/20flap/S821fa20.htm
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That’s Funny John Hill says that I deliberately try to lead Dallas into the briar patch. Back awhile, it was Dallas flyers (some not all) that adopted the inboard mounted ST60. Even though my local friends saw how well it performed, they wouldn’t try it. Tom Farmer tried it and numerous Dallas flyers followed suit. I see you’re canard is going to be electric, so you’re off the hook for the inboard ST60, but it’s not too late to try the slotted flaps.
Yes the gap at neutral, just enough for clearance. The flap airfoil shape, mainly the leading edge, is a good question. Roundy but not too blunt.
The real critical point is the hinge offset location. Offset location in relation to the flap leading edge shape. You’d like the optimal gap to occur at about 30 degrees of deflection (I’m guessing here) It seems like the proper offset is about 3/8 to ½ inch. Check out the link below. I think he shows the pivot at about 0.97% of the main wing chord.
http://tspeer.com/RigidRigs/20flap/S821fa20.htm
i may have to rename the plane the "Toy Box" the way it is going. With so many goodies (when you can't fly much you get stuck playing with new ideas) on this plane Cam Rudder, Independently adjustable Logarithmic flaps (yes this will still work with them), a Canard, adjustable accelerator mount to name a few.
Just for the sake of argument, if I use a parabolic flap LE that stops moving at 30 degrees (that is where the current horn stops. It is really cute, Mark Wood designed it - see pix) and set it so that the center point of the flap LE is just past the top/bottom of the wing TE am I on the right path? Mark was working on a similar idea except the pivot was deep into the flap and the movement was inside a cupped wing TE. I like yours better since it more closely follows the gain from the detached Fowler designs. Now, going from theory to a working flap. I would use 1/16 x 14" CF for the flap mounts and make some sort of hinge at the end. I see the biggest problem will be getting the flaps stiff enough that they don't twist with the extended hinge. No idea what happens as the gap starts to open/close. Control forces will be non linear and it could easily make locking harder. I would suspect that when the airflow going through the gap starts flowing over the flap below the wing that there will be a sudden and rather dramatic difference in how the plane handles. All of this adds up to maybe I don't want to try this....so where do we start?
Maybe this is all a huge waste of time but isn't that the very definition of a great hobby! Here is a link for a working version of Mark Wood's flap gizmo.
https://www.youtube.com/shorts/R73jeLaCKz0
Ken