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All Forums >> RC Airplanes >> S.P.A.D. Aircraft - Coroplast design >> Canadian SPA3D
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Canadian SPA3D - 7/8/2003 6:17:16 PM   
`3D


 

Posts: 280
Joined: 5/15/2003
From: here,
Status: offline 		[QUOTE]and the more ridged the wing gets the less stable it becomes...and it tries to wobble (six million dollar man syndrome) at slower speeds. Without the airfoil fold, the Spa3d wing flexes noticably more than the QHOR, but we learned from the pbf's that this flex provides "dihedral on command" and provides incredable stability[/QUOTE]


Thats what the misic wire in the wing does, "dihedral on command", too ridged in the front, and maybe not ridged enough in the back...did you put the wire in the trailing edge before the ailerons?????

(in reply to Ross Kean)
       Post #: 26

Canadian SPA3D - 7/8/2003 10:12:33 PM   
Ross Kean



Posts: 686
Joined: 6/4/2002
From: Fredericton, NB, CANADA
Status: offline 		The plane is quite rigid along the leading edge fold. It is somewhat less rigid along the trailing edge, but not enough to make it unstable at slow speed. As far as the LE is concerned, in hover or slow harrier there should be very little force for "dihedral on command" so I would not expect the airfoil to be bent very far from flat. It would be different in the wind and in a somewhat faster harrier. No stiffeners in the TE before the ailerons, but the isn't too much flop. in the surface.

(in reply to Ross Kean)
       Post #: 27

Canadian SPA3D - 7/9/2003 10:11:05 PM   
hoveralot


 

Posts: 143
Joined: 1/8/2002
From: Caracas, VENEZUELA
Status: offline 		I had lots of troubles in my first flights with the ballooning attitude but I found that my CG were too far back, know in my 7th flight (I flew the Spa3d at 7 1/2" CG six times no crash) moved the cg to 6" and move up ailerons about 1/8" above the rail bottom, airplane now is more stable but it still needs 1/2" of down elevator to fly almost straight.

Do you think I should use about 1/4" up for the ailerons to prevent the airplane to fly nose up during flight?? It does nice harries as it is now but donīt like the ballooning attitude every time I take off.

By the way with the CG at 7 1/2" flat spins were so nice

I love this plane and more and more fun fly pilots here in Venezuela feels attracted by the design.

(in reply to Ross Kean)
       Post #: 28

Canadian SPA3D - 7/9/2003 11:37:24 PM   
Tattoo



Posts: 2124
Joined: 2/10/2002
From: Wichita, KS,
Status: offline
quote:

up ailerons about 1/8" above the rail bottom, airplane now is more stable but it still needs 1/2" of down elevator


If moving the ailerons up as you describe made the aircraft performance better, then by all means, keep going a little at a time and see if it keeps getting better. Eventually you will reach the "sweet spot" where it's as good as you can get it, before starting to get worse again. Where the surfaces end up in their neutral position is less important than having your plane fly the way you want it to.

quote:

No stiffeners in the TE before the ailerons


The music wire just in front of the ailerons is very important, and something we learned when strapping larger engines to these planes. It was theororized that when giving aileron input one direction, the force on the wing caused it to flex in the opposite direction...negating the aileron input. When Kraut strapped a GMS .47 on a stock PQHOR...man...it barely rolled and was a wild ride! I'm going to have to say this theory is correct, because he inserted the music wire...and regained all control and his roll rate!!!

BTW, it was because of reading about the music wire somewhere in a forum that we tried it, and immediately incorporated it into the Spa3d design. Whoever it was that did it first, please let us all know so we can thank you!!!

(in reply to Ross Kean)
       Post #: 29

Canadian SPA3D - 7/10/2003 12:03:58 AM   
den1tjb


 

Posts: 214
Joined: 12/7/2002
From: Littleton, CO, USA
Status: offline 		Let me just add one thing ross....you are NOT going to destroy this airplane before you trim it out. I am working through some of the same problems you are, but even with a wild plane it is a ton of fun. 4 of its 5 flights have ended with it going STRAIGHT in from about 50' (the fifth clipped a wing on a low pass an cartwheeled about 3 times). With each crash, the only damage is the L.G. mounting screws coming out of the POLY engine mount. Either drive a new set in the old holes (they seem to hold very tight even though the holes are stripped out completely), or take a few minutes to throw a new engine mount on.

But this is all great information. I have the whole day off tomorrow which I plan to test fly, and try out some of these techniques. Thanks for the great design!


_____________________________

Could it be that all those trick-or-treaters wearing
sheets aren't going as ghosts, but as mattresses?

(in reply to Ross Kean)
       Post #: 30

Canadian SPA3D - 7/10/2003 12:46:14 AM   
`3D


 

Posts: 280
Joined: 5/15/2003
From: here,
Status: offline 		Mine needs a little elev down trim as well, but flies good that way.


[QUOTE]The music wire just in front of the ailerons is very important,[/QUOTE]



I've seen where peeps have sealed the ends of the wing with a piece of 1/2" coro (thickness of fold/channel) to stiffin the wing.

But I am woundering...if you look at the wing from the front you see that the wire & fold make the wing a little fatter in the center of the wing and sort of tapers a little to the tips....sort of like a stealth wing.....so what if I/you/we tried glueing/sewing the wing tips together???

(in reply to Ross Kean)
       Post #: 31

Canadian SPA3D - 7/10/2003 3:59:36 AM   
Riverdancer



Posts: 198
Joined: 2/27/2003
From: Edmonton, AB, CANADA
Status: offline 		Good day Guys,

I didn't read the whole thread, but wanted to throw in a loonies worth (Canadian Reference). Have to go easy on the new guys to SPAD... if you have never flown one before they are a bit of a hand full.. I only have about 20 flights on the QHOR and it flew like crap to start with(Emphisize"No fault of the design" I had the aileron drop thing going on, really aft C of G not enough throw in the ailerons and too much in the elevator.. Just Takes time to get used to..and trimmrd out.. for the Canadian boy there Keep at it, Tatoo is right they are way too much fun and keep in mind they are only $20 airframes (Canadian $) Oh yeah and Ross I have a couple of mods that I busted in that make the QHOR fly very well even fast (46fx ultrathrust muffler 11x5 APC), Some copied, some of my own. I have almost completed the SPA3D with the same mods and am looking forward to it:0)

PS: As allways, hats off to the SPAD guys... they have a great thing goin on here:0)

Take Care for now,

Riverdancer

(in reply to Ross Kean)
       Post #: 32

Canadian SPA3D - 7/10/2003 5:06:02 AM   
Ross Kean



Posts: 686
Joined: 6/4/2002
From: Fredericton, NB, CANADA
Status: offline 		Riverdancer:
I have been building and flying SPADS for almost three years and I am pretty familiar with getting them trimmed out. This one is probably #10 or so. This one has been a bit puzzeling because the usual stuff doesn't seem to work the way it should. I have 6 or 7 flights in at this point and I have had no worse than one "firm" landing when I deadsticked. Result was a muddy prop and bent wire gear. Other than that I am being pretty careful and am trying to analyze performance rather than try to do too much crazy stuff.

Its been too busy at work to do much for the last couple of days but the next step will be to see if I can stiffen the trailing edge a bit (not particularly bad at this point). Although the ailerons are a bit up from parallel to the rail, I'll go a little more until performance falls off the other way. Once this is as good as I can manage, I will attempt the great center of gravity experiment! 6 1/2" to start and I may go as far a 8" - that should be a wild ride!

Even with problems, it's a real hoot!

Ross

(in reply to Ross Kean)
       Post #: 33

Canadian SPA3D - 7/10/2003 6:22:07 AM   
secondchildhood


 

Posts: 166
Joined: 7/28/2002
From: Collinsville, IL, USA
Status: offline 		FWIW I put bamboo skewers in the ailerons about 1/2 way the distance of the length of the control horns, (as well as the recommended music wire in the wing. This helps keep the ailerons from flexing so much and seemed to help a bit. On this SPA3D (A10 Warthor- see post at Spadworld) and the previous QHOR (BamBam's Vanilla Coke) moving the CG back definetly helps a lot on hovers etc, but does make it considerably harder to fly conventional. After much experimentation, I finally settled with about 1/8 to 1/4 up reflex on the ailerons, and cg according to plans. For those who say it is hard to fly conventional, move the CG fwd, or at least back to the plan dimension, reflex the ailerons up, and go have a ball.

Dwight

(in reply to Ross Kean)
       Post #: 34

Canadian SPA3D - 7/10/2003 6:33:50 AM   
Johnnylightning



Posts: 608
Joined: 10/31/2002
From: n/a, , USA
Status: offline 		[QUOTE]Originally posted by `3D
Mine needs a little elev down trim as well, but flies good that way.[/QUOTE]
Me2

As a suggestion, the easiest way to set spoiler-up trim is w/ a mixed wing config on your tx. I used my flap pot and "dailed-in" spoilerons IN FLIGHT 'till it flew stable. If your tx is capable, loose the a-ron y-harness and "mix" flap to a-ron. One of the many great features of this aircraft design, is that everything is easily accessible.

Don't give up...yours may have the answers to many of these questions.

_____________________________

OPEN YOUR MIND...but not too much, your brain might fall out.

(in reply to Ross Kean)
       Post #: 35

Canadian SPA3D - 7/10/2003 8:46:03 AM   
Crash90



Posts: 2315
Joined: 10/5/2002
From: Cressona, PA, USA
Status: offline 		How is this for a theory. I know nothing about aerodynamics so I am just shooting from the hip.

You built your SPA3D and set both ailerons level with the bottom of the fuselage.

You take it to the field and upon takeoff the right wing drops. You immediately give it left aileron until you get some height then proceed to give it 4 or 5 clicks left aileron trim to get it flying straight.

If that is the case. Is it possible that using aileron trim, lets say 4 or 5 clicks of left is droping the right aileron down below the fuse causing an unstable flight?

You come home and ask RCU what the problem is and somebody mentions raising the ailerons 1/8 to 1/4 inch. After raising them and setting them level with each other you take it to the field. Upon takeoff the right wing drops so again you add 4 or 5 clicks of left aileron trim. This time however because the ailerons were up 1/4 inch, the right aileron doesn't drop below the fuselage which is giving you a more stable flight. However the spa3d wont fly real stable unless the ailerons are in line with each other?
Possibly setting both ailerons at 1/8 inch above the bottom of the fuse and using weight to "trim" the plane laterally will solve your problem. Just a wild guess. Tattoo.Kraut what do yah think?

(in reply to Ross Kean)
       Post #: 36

Canadian SPA3D - 7/10/2003 5:57:57 PM   
`3D


 

Posts: 280
Joined: 5/15/2003
From: here,
Status: offline 		[QUOTE]You take it to the field and upon takeoff the right wing drops. You immediately give it left aileron until you get some height then proceed to give it 4 or 5 clicks left aileron trim to get it flying straight. If that is the case. Is it possible that using aileron trim, lets say 4 or 5 clicks of left is droping the right aileron down below the fuse causing an unstable flight?
[/QUOTE]

Yes...my trimmed 3D has more rt up aileron than left. (I think one wind has a little more lift, due to uneven LE fold).


Well..I tried pinching the wing tips together, I just took out the 1/2 wire and put one in tight.

No ill effects at all, actually gives the bottm half of the wing a little dihedral, seems like it snaps back to level fight a little better.
Maybe a little more wing wag on slow approch.


ALso I added a Mousse Can Muffler as per Kraut's method
http://www.spadtothebone.com/SPAD/Mufflers/

Accept I didn't use the 3/4 pipe, it just so happen that the small end of the can fit the front half of the stock muffler perfect, just had to drill two holes, (exhaust outlet, thru bolt hole), and bolted it on. Now my .46 will pull vert's with a 11 x 6. Horsepower for a buck..I love it... .

(in reply to Ross Kean)
       Post #: 37

Canadian SPA3D - 7/20/2003 8:13:36 AM   
Ross Kean



Posts: 686
Joined: 6/4/2002
From: Fredericton, NB, CANADA
Status: offline 		I have finally managed to get back to the SPA3D.

A few things:
1) I found that the lack of elevator authority was largely due to too long/flimsy pushrods. I stiffened up the elevator and rudder pushrods with 1/4" dowels.
2) Center of gravity seems to be near optimum at ~6 1/2". I tried some weight in the tail and had one wild ride! The CG ended out between 7 and 8". Took off OK and I could keep it in the air but knew within a couple of minutes that the landing wouldn't be pretty! Got worse as the fuel burned off and landing was less than gentle - only bent wire gear to show for it
3) I have come to the conclusion that excess engine power would be a real help and I may try another powerplant. My Magnum 40 XL is not a real winner although much better than it was since I changed to a Thunderbolt #3 plug and higher nitro.

The main differences between my SPA3D and the "stock" are twofold. Mine is a little heavier due to the thicker material for the rail (1"w x 3/4"h x 3/32thick). This rail is very rigid and would be great for a larger plane. The leading edge fold is a little thicker due to the larger channel (just over 1" radius) and the LE exhibits little or no flex because of the foam blocks glued in - I thought this would be a good thing!

The lack of flex in the LE might explain slightly poorer performance in high alpha flight; harriers etc - no automatic dihedral. Should make little difference in static (hovering) flight.

This plane is fun and the flag looks great in flight so it will definately get some air time but overall I am a little disappointed in the performance. I have tried everything I could think of as well as many of the suggestions in this thread.

I hope I get a chance to see a great performing SPA3D fly sometime. It would be very interesting to do some side-by-side comparisons to see if I can determine exactly what I am missing in my version.

Ross

(in reply to Ross Kean)
       Post #: 38

Canadian SPA3D - 7/20/2003 8:18:37 AM   
ChrisSpad



Posts: 1525
Joined: 4/19/2002
From: Cordova, TN,
Status: offline