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Designing and building your own aircraft

slobird

Registered User
Erwin, TN
Not being an aeronautical engineer, it may seem crazy to propose such a route, BUT I've got 4000 flight hours with a lot of them in military recon a/c. Now I'm retired, haven't got much money, but still love to fly around the tree tops slowly. I've got some ideas that might interest other guys like me, who would like to help design, or assist in the design and possibly help find some free professional assistance for a very light, slow flying, easy to build. cheap bird.
 
I'd like to bounce some ideas around.

Also, Wayne Mackey would surely like to chat with you.

Look into some of the threads on "art and science of flying". You'll find some cool stuff there, and also Wayne's phone number.

Welcome, Slobird.

Dave
 
stol

Slobird,
I always injoy talking stol aircraft projects with anyone. 406 232 1370. Wayne
 
I like slow flight too.
Jim Cunningham
Cunningham Engineering Assoc.
901-268-9304
jrccea@bellsouth.net
P.S. Am interested in designing a stand-off scale replica of a Dragon Rapide, using a pair of 337CE Lom's. Anyone interested in the DH 89 ?
JimC
 
tail

Jim C,
Good to hear from you. Have you had much to do with a flying tail, stabilator.
Looking for info on lay out and balance. Wayne
 
Hi, Wayne. I have a Cherokee 150C with a stabilator. They're OK, being slightly more efficient than a conventional horizontal stabilizer with elevator, but will need a mass balance. They're kind of touchy about flutter even with the mass balance. I don't dislike them, but would just as soon have a tail with elevator.
JimC
 
tail

JimC,
The reason for the stabilator for me is the slat slow flight. With the angle of attack
so high the stabilizer blanks out most of the elevator. With stabilator I can get around
that. Wayne
 
Wayne, that makes sense. Do you want a rectangular tail or one with a planform shaped more or less like a conventional super cub? Rectangular is easier.

If rectangular, take a good look at the horizontal tail on a Cherokee as a starting point. If I remember correctly, they have about a 9% t/c ratio. You'll need a wide, full span trim tab similar to the one on the Cherokee (trim tab automatically goes down when the stabilator goes up and vice versa). I'd recommend hinging the trim tab on the top like the Cherokee, and use some of Art Mattson's gap seal tape to seal the top of the trim tab hinge line.. Duplicate the Cherokee ratio of stabilator in front of the spar and pivot to that behind, and use the Cherokee type mass balance and swing arm. It might be easiest to just get a Cherokee horizontal stabilizer from a salvage yard and modify the span and control linkage to suit your needs.
JimC
P.S. look at Art Mattson's website for the composite takeoff photos to get an idea of how well the Cherokee stabilator can function during extreme takeoffs (extreme for a Cherokee anyway). To find Art, do a google search for +speed +Cherokee +amrd (or +amr&d , I forget which).
 
Wayne, go to

http://www.pipermods.com/

And click on 'Great Takeoff Performance' up at the top left side of the page to see the photo sequences that I was describing. I've flown this particular plane in the Denver-Oshkosh air race, and the composite sequences are realistic. It's not trick photography.

JimC
 
P.S. again
Wayne, I'm pretty sure that you're already aware of this, but with a stabilator you won't be able to use guy wires to brace the tail, so the vertical tail spars will need additional reinforcement to allow those spars to carry the yaw loads as a cantilever beam rather than as part of a truss.
JimC
 
I have been designing and building an airplane similar to a cub. I have the fuselage on the gear, the wings with the ribs on the spars, the internal wing bracing in place, and working on mounting tail feathers right now. This airplane is alittle smaller than a cub but bigger that the Kitfox type airplanes. Will handle engines from 65hp to 150hp. Wingspan is 33ft. Hope to wieght about 700lbs. with an 0200 and gross 1500lbs. I have designed several other planes mostly radio control models and modified a Pa-22 into something similar to a bushmaster or producer. If you don't plan on going fast, it is not rocket science. Put the tail on one end or the other, get the Cg right and it will most likely fly. Although maybe not very good. There is alot of factory stuff that doesn't fly very good. Building experimentals is great, you can really use your imagination.

Don
 
Jim C., I've been interested in the Dragon and the Dragon Rapide since I was a kid. It might be just the most attractive aircraft ever. Floats, wheels, skis.....the thing did it all.

Also, I've been looking at using the cherokee stabilator, as well. Jim, with flutter being such an issue, why did Piper designers servo-tab this design. Something is not adding up here. Or was your earlier description a summary of the "trimming" action of the tab??? "stabilator goes up, trim tab goes down".


Not trying to bust your chops, just clarify things
 
Say - rushing in where angels fear to tread...if mounted correctly, is flutter still a serious issue with the stabilator at the slow speeds you're intending to fly? (given a top end of 95 mph or so)
 
David, I too think that the Rapide may be the prettiest airplane of all time. Unfortunately, the DeHavilland support group won't sell you a set of plans unless you already own a Rapide. However, just as a lark I'm working on a set of AutoCad drawings based on scale views so I can get a better idea of the dimensions involved. I'd rather use a pair of Lom 337CE's (250 hp each) than the original Gypsy Sixes with 200 hp. Also, the plane could be built as a slightly down-sized stand-off replica, which would greatly improve the climb performance if one used the CE's. But I'm mostly just dreaming. I've been looking about for a clunker to start from, but they're hard to come by and a tad overpriced.

The full span stabilator trim tab is to modulate the stick forces. The mass balance is what combats flutter. My description was ambiguous. And, no sweat, I knew you weren't trying to bust my chops. As an aside, I make a fair fraction of my living as a witness in fluids related litigations with the other side being paid to bust my chops, so I've become remarkably insensitive to chop-busting anyway. :)

And Cubus, at slow speed flutter might not be much of an issue. But I'd rather not find out by trial and error. I have a personal talent for error, and can make three where one would suffice to do me in.

All the best,
(and Season's Greetings)
JimC
 
I've flown enough of them and should remember, But isn't the Cherokee hor stab tab a anti-servo?

I've flown a Cub with PA18 tail feathers that had a true servo tab (experimental). So light and quick on the stick it was almost scary if you are used to a normal Cub.
 
Mark, I'm not around them enough to remember. I can find out tomorrow easily enough, but maybe Jim will get back on here and tell us.

I'd not be looking for lighter pitch feel on the Cub series, no need for that, but am interested in the stabilator for the same reasons as Wayne.

Anyone ever work with a variable incidence wing. Something like a drooping rear wing fitting? Just an idea right now. I'm wondering if anyone else has already ruled it out?
 
C.G. Taylor tried variable incidence in 1929, the Giggenheim competition plane, the C-2. It was a flop. Flaps do the same thing only more effective and simpler.

I think(?) the Cherokee and Commanche stabilators have anti -servos. The Cessna 177 did not, if I am thinking correctly? The 177 had some serious tail stall issues, and the later models maybe had slots in the tail to help this? Can't really remember the details, but it might be worth researching these aircraft.
 
Yea, the Cardinal has slots in the tail. A tee post really messes them up when it goes through it after the pilot lands in a field after running out of gas.
 
David wrote:
> Anyone ever work with a variable incidence wing. Something like a drooping rear wing fitting? Just an idea right now. I'm wondering if anyone else has already ruled it out?,<

I spend most of my time doing research on the flapping flight mechanics and unsteady aerodynamics of late-Cretaceous azhdarchid pterosaurs, primarily Quetzalcoatlus species and Quetzalcoatlus northropi. They are an extreme example of variable incidence wings, but not quite the type you are referring to.

In my opinion, a variable incidence wing on a cub would be primarily useful for trimmming fuselage drag in cruise flight. And to some extent, allowing greater aoa during takeoff without going to extended gear But I think it'd be too complex to be worth it. If I were going to go for really high lift in a Cub, I'd probably use a modified Selig S1223 or an S1223RTL rather than a modification of the Cub airfoil. But the 1223 would require a lot of tail authority.

And to respond to your original question, there has beeen at least one aircraft that let the fuselage swing free of the wings during high aoa flight. I don't remember who built it. It was a one-off.
JimC
 
Yes, to trim fuselage drag in cruise and allow greater AOA on takeoff without long gear or poor over-the-nose visibility.

Lots of problems to solve before we'll see one fly on a Cub. As I said, just an idea.

The earlier Cardinals had no slot in the stabilator. I have not flown one. Apparently the slot makes alot of difference. I'm sure the fence post made a difference, too, Steve. :eek:
 
David M. Calkins said:
Yes, to trim fuselage drag in cruise and allow greater AOA on takeoff without long gear or poor over-the-nose visibility.

Lots of problems to solve before we'll see one fly on a Cub. As I said, just an idea.

The earlier Cardinals had no slot in the stabilator. I have not flown one. Apparently the slot makes alot of difference. I'm sure the fence post made a difference, too, Steve. :eek:

David, did you get my PM?...
 
Of course there was also the F-8 Crusader style variable incidence wing.
 
tail

Guy's,
thanks for all the input on this, I'm out of town on a barrowed comp.
When I get home I'll get back to this. Wayne
 
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