flat spin problems, what is causing this death spin.
 

I have a Kyosho agwagon. It is fairly aerobatic, but in certain manuevers, most Im using rudder,it trys to flat spin coming out of it. Now i know that a real agwagon put into a flat spin will never come out of it. Mine has mod wing tips that are pointed up, kinda a small verticle wing. Does anyone have a idea to why it wants to do this death manuever? Is there a way to stop it?
My theory---At the end of the stunt, the plane stalls , when im using rudder, it trys to flat spin. I have enough engine to pull it out, but it has almost not made it several times.

flat spin problems, what is causing this death spin.
 

If you are slow and in uncoordinated flight then there is a good chance for a stall/spin. The spin would then flatten due to an aft CG and/or lots of elevator throw. Moving the CG forward may help some, as well as maintaining enough speed through your maneuvers to prevent uncoordinated stalls.

flat spin problems, what is causing this death spin.
 

My agwagon has lots of elevator throw, and is major nose heavy.
Im running a .70 OS 4 stroker on my agwagon, i got the power, but it seems on a exit, heading at the ground, it will spin a few times, and scare the crap out of me. AAAAHHHHHHH.lol.:D
thanks for the info falcon.

Spins
 

If it is truely "major nose heavy" that's as bad or worse than tail heavy. A very nose heavy aircraft will stall/snap/spin in a heartbeat, particularly when using lots of elevator out of a dive. Tied to very large elevator throw it's no wonder the airplane is scaring you. A nose heavy aircraft situation works the wing the hardest because it has to generate more angle of attack to fly the airplane, leaving little left over for maneuvers.

A tail heavy airplane works the wing the easiest but it also causes pitch up's which lead to stalls and maybe spins. An aft Cg is the usual cause of a true flat spin (rotating in yaw with fuselage parallel to the ground). Power (with recovery controls) is the only thing that will get you out of a flat spin.

Recommendation: remeasure the Cg and get it to 25-30% of the MAC.

flat spin problems, what is causing this death spin.
 

Dago:

When the P-80 (F-80) was developed into the T-33 it had a bad characteristic: control departure often put you in the grip of what was called "TheThing." Guess what.

On the T-bird this was solved by adding empennage area. Logic tells me it was added to the vertical fin, but memory says it was added to the horizontal stab.

but on a small plane it's eay to try, and hurts nothing.

Cut a triangle of medium balsa, fit it to the front of the vert fin, make it look like a P-51d. Stick it on with Shoo-Goo or something else that will come off when you want it to. Fly it. Improvement? Make one a little bit larger and try again. When you stop getting improvement, do the same triangle trick to the stab. You will find a combination that will work fine. Might take several tries.

When it flies as you want it, then make nice parts to go where your temporary ones were, glue them in properly and paint/cover them. Fly happily.

Twin caught in "The Thing? Either get out, or "Ka-Ching!

Bill.

not sure
 

im not sure what u mean William Robison, but is this what you mean on the vert stab? Like the stang. The agwagon has few caracteristics like the stang to start out with, so i might all ready have them on the plane.
My next option its to throw some weight into the tail to balance it.
thanks for the info.

flat spin problems, what is causing this death spin.
 

this is the most recent picture of my agwagon. I had a 4 blade on it, sounded and flew great. now im back to a 13-6. I had to put quite a bit of off thrust on to engine, it torqued over on almost every take off, now I dont have a bit of problems with that.

flat spin problems, what is causing this death spin.
 

Those little tiplets of yours are awfully far forward in the wing. Perhaps these are creating a de-stabilizing force that's competing with the vertical fin and rudder. My advice would be to rip them puppies off and see how the model flies without them.

Are they scale? I can't imagine them being shaped like that for full size. They don't look like the usual NASA winglets at all. For starters the ends of the ailerons are exposed. Certainly they would make lousy end plates for controlling tip vortices with then being so short at the rear. Perhaps this is what is causing the nasty tip stall, the vortix is sneaking around the ends of the ailerons and doesn't want to let go until you power out of the spin.

And I think what Will is reffering to is often called a dorsal fin or dorsal gusset. It's the short ridge running along the upper fuselage from the base of the more normal fin, ie: the bit they added when they went from the B model to the D model. Actually you've already got it.

flat spin problems, what is causing this death spin.
 

I thought I had that little gusset.
The tips arnt scale, I made them after I cartwheeled the plane, destroied the scale wing tips--the cost of the wing tips are i think $30 a pair. The original curve down, hard to make.
I want to have wing tips on it, but what other kind of wing tips can I put on it to make a better flying plane, do I need to make them longer?
To tell you the truth, after I put these on , the plane turned better and didnt fall in a turn, as if acting as wings.
Do you know any NASA wing tips I can put on this puppy, that look good, make it fly better, and fairly easy to make, consider it took 2 hours to make the ones on it right now.

the first wing tips.
 

you can see the original tips are nothing like my mod tips.

flat spin problems, what is causing this death spin.
 

Bruce:

Seeing his picture I agree 100% on his wing tip destabilizers. Rip off what you have there, Dago, and replace them with flat plates extending from the LE to the trailing edge of the ailerons. Make then exrend no more than 1/4" to 3/8" above and below the wing. I think you'd probably be better off with nothing than what you have.

And Bruce, "Right again, Robin," it's the fin gusset I was talking about. If the correction of the tip abomination doesn't take care of the problem, add the gussets to the stab. With those instability generators off the tips shouldn't need anything else.

A twin with those fences, rather lose my senses.

Bill.

PS: Dago, the original are called "Hoerner" tips,wr

flat spin problems, what is causing this death spin.
 

Hum, this was simple, I think we solved my spin problem in one day, since I dont have time to build them tonight, ill build them tommarow and try them tuesday or next saturday. Ill report the results for ya'll.
Now for a second question, why is it that this plane can not recover from the a flat spin (death spin)? I think it is because of the high amount of dihedral this plane has.
Another mod I made to this plane is build a tailcone that is about 1/4" longer than the stock, not much, but it looks better, does that tail cone being lengthand have any thing to do with its flight caracteristics? I heard on the real agwagon, if you dont have that tail cone, its not safe to fly.
I think as you guys can tell, this agwagon is not a stock kyosho agwagon.:D

flat spin problems, what is causing this death spin.
 

The small rudder certainly won't help getting out of a flat spin.

flat spin problems, what is causing this death spin.
 

the rudder on this plane isnt that small? Do you mean the vertical stab, or the moving rudder. Sorry if i sound , well, the way i put thing isnt all that smart sounding. do i need to extend it ,kinda like a cap 232 rudder?lol.:D

flat spin problems, what is causing this death spin.
 

Dago:

What Ryan is talking about is exactly what I said to start with, in different words.

If replacing the vortex generators with plain tip plates doesn't remove the tendency to flat spin, increase the size of the dorsal gusset until you have no further improvement, then if there's still a problem do the same to the stab.

Yes, if you would rather, you could increase the rudder area. The gusset is easier. More rudder area might work better, though.

Flat spin recovery requires the tail plane to be outside the air disturbed by the wing. That's why you can power out with a prop plane, the propwash blows the tail "Free" of the vortices, but low to medium power jets have to be knocked out with flaps, dropping the gear, or anything that can radically alter the airflow. A high power jet sometimes can be blasted out with thrust.

Twin in a flat spin? Wait, see how far it'll dig in.

Bill.

flat spin problems, what is causing this death spin.
 

Later Tiger moths had dorsal strakes on the front of the stab at the root to stop unrecoverable spins. If you got into an inverted flatspin with a Harvard you were told to bail out. Unrecoverable!

flat spin problems, what is causing this death spin.
 

WR, the Hoerner wing tip is not downturned.

The Agwagon has A-10 style downturned wing tips.

flat spin problems, what is causing this death spin.
 

York:

I am not the ultimate information source, I have been known to err.

But I will draw your attention to Cessna. The late 150 series is advertised as having "Hoerner" wing tips.

The wing tips on the late Cessna 150s curve down.

Maybe "Hoerner" has to do with the vortices generated rather than a particular curve?

Twins with Hoerner, are for a fast burner.

Bill.

flat spin problems, what is causing this death spin.
 

I've also seen these identified many times as reversed Hoerner tips way before the A-10 used them. The Maule Rocket used this type of downturned tips for one.

flat spin problems, what is causing this death spin.
 

Ok, last night I added 4-5 inch monster truck wheels to the agwagon. our field is wet, and muddy right now. On the test flight every thing went on. I did all the normal manuvers that sometimes had the begining of a flat spin after. I never had it try to flat spin, but I did stall it, and it was tip stalling side to side while falling.
Could these monster tires have stoped the the flat spin episode?
Im going to remover the wingtips this week and build the flat plate wing tip for it.
Perfect flying day, my biggest problem is the tire came off the rim on a landing, funniest thing Id ever seen.

here they are
 

ok guys here are the new wing tips, what do ya thin, painted with black and 18 karat gold paint.

flat spin problems, what is causing this death spin.
 

Dago:

A little crude but should be more than good engough for a test. You can always round off the front corner.

A twin, said the owl, requires a second cowl.

Bill.

flat spin problems, what is causing this death spin.
 

Ill probabaly leave the the way they are,Im running out of paint, Ill test the plane this weekend and let you know what happens.

flat spin problems, what is causing this death spin.
 

Ummm, ...... this may be a silly questoin but why do you want tip plates instead of just a plain old sorta streamlined rounded tip?

flat spin problems, what is causing this death spin.
 

Bruce:

Possibly at my suggestion. This way he has a lot of the advantages of the (reversed?) Hoerner tips, without the aggravation of carving them.

Keep at it, Dago. We're with you.

Rounded, drooped tip or a plate, I like twins, they all fly great.

Bill.

flat spin problems, what is causing this death spin.
 

I want something different on my agwagon, as if its already different.If the tips dont seem to do any differ I can always try standard. although I did like the way it looked with no wing tips.
thnaks for the encurage ment, The test flight is goign to tbe run with stock 3 inch wheels, not 5-6 inch monster truck wheels,lol,:D If theses dont work i have some other wing tips to try, ill take a picture,
P.S. I made my wingtips screw on so Ican replace, or put on new wing tips .thank god I Decided to do this!!

flat spin problems, what is causing this death spin.
 

Well, if all you want is something a little different then you may want to try these. This is sort of a poor man's Hoerner tips that I've seen used and used myself over the years. They are dirt simple and may just fit the bill for what you are trying to do here.

Take a block of square balsa that is as deep as your tip airfoil and slice it at 45 degrees. Keep it square until the angle is shaped so they don't end up out of kilter (there's those tech terms again... :D ) Now glue, or in your case, mark and drill the holes to fit your wingtips. Now shape the blocks so they blend flush with the airfoil top and bottom. Tape over the finish on the wing so it doesn't get marked during the shaping and sanding. Now glue on the swoopy looking tip plates and match them up to the blocks. This will give you some 45 degree tips that either tilt up or down.

So, which way? Down will hold the air in under the tips better during landings but have an adverse dihedral effect. The upturned tips will provide a bit of diherdral rolling action that may sharpen up a snap roll. But either one should have a little less disturbance to the tip flow thanks to only being on the one side and the more open angle that the plate meets the rest of the airfoil.

And they look pretty darn good too.....

flat spin problems, what is causing this death spin.
 

Im sorry ,BMatthews , My internet provider is having problems latley and wont open thumbnails,can you email it to me, thank you, from what i can see ftom the small picture, it looks unique, something to put on the agwagon it performance dosnt improve.

flat spin problems, what is causing this death spin.
 

well guys, the tips were never tested the plane crashed on take off??????

flat spin problems, what is causing this death spin.
 

Dago:

Very sorry.

Do you know why? If you don't please describe the whole thing, maybe we can all learn from your misfortune.

Never seen one that could not be repaired, but I have seen damage to the point that replacement was easier.

Don't know if I told you about it, my first major crash in years was in that total trash category, (High speed inverted pass, ran out of down elevator) but I didn't throw anything out. And I just started the repair.

Your twin has had its very first crash,
. this is the time to do that bash.

Bill.

flat spin problems, what is causing this death spin.
 

Ok, heres my description from taxi to takeoff.
I taxied to the center of the runway. I gave it the throttle to start rolling, once she was rolling i gave about 3/4 throttle, she lifted off, so i gave the rest 1/4 throttle and procided to make a left hand turn away from the field, she seemed to procide for a second then made a huge right hand turn sight in to the ground hitting the wing first busting it in to 2 major pices with about 30 splinters. the fus was crashed behind the wing with the wing hold down ripped out, broke the prop and left a deep hole in the runway. Every one likes how I crash, on the runway so we can see the pieces fly. It broke off one wing tip, do you think wing tips have somthing to do with it, ever since I put custom wing tips on it seem to do strange things on takeoff. the firewall is still in plane,lol. ill take some pics and post them.
not sure what is wrong with it, but im starting to think its the wing tips, need to by those $30 wingtips for it.

agwagon crash pics
 

here

flat spin problems, what is causing this death spin.
 

again

flat spin problems, what is causing this death spin.
 

last for now

flat spin problems, what is causing this death spin.
 

OUCH.....


Sorry to see that DR. There's no doubt that the style of plate tips you have used so far are a destabilizing force. Even the stock Hoerner tips would have been a slightly destabilizing influence but the model was apparently able to handle them.

I would say that despite how it looks you can fix it but it's going to pick up some weight which will tend to make it even more touchy for stalls and all. But it would make a good test bed for experiments.

I'll still send you that jpg on the tips for the next one.

flat spin problems, what is causing this death spin.
 

Dago:

I've done worse, looks repairable, even if half the wing is new construction.

Confirm: She rolled right out of a left turn? If yes I would dismiss any aerodynamic cause.

Give the radio gear a very close inspection, the bits have had a somewhat hard life. If a glitch gave you hard right rudder that could be the cause.

And I'd hate to think the tip plates did it, especially since I told you to try them.

Ideas, Bruce?

Check everything, Dago, let us know.

I may be totally a dunce,
. but I don't think it could spin both ways at once.

Bill.

flat spin problems, what is causing this death spin.
 

Ideas? Well I think a lot has to do with this quote....

How much time did this turn take and what were you doing on the controls when it happened? If it took more than a second and nothing you did seemed to help then I'd suspect radio problems too.

DR, what sort of rough life has this set had in the past?

Crash
 

Ahha, accellerated stall, aggravated by adverse yaw at low speed with the nose heavy condition. I think you got so wrapped up in the wingtip thing you never got around to addressing the underlying Cg situation (see post 3, etal). No radio problems here whatsoever.

Re: Crash
 

I think a lot depends here on how long that "huge right turn" took to execute. All the CG aggravated responses I can think of would take place in not much more than the blink of an eye.

Not saying you're wrong but I think we need more info to judge properley.

flat spin problems, what is causing this death spin.
 

Try right clicking the thumbnail and you should see the first item is "open link". If that doesn't take you to the full size pic I'll email the file to ya.