balsadust74

My Feedback: (3)

I have a question on regarding my Great Planes Extra 300. It is the 40 size Extra but I have an O.S. 61 FX turning a 12x5 prop. When I pull back on the stick from level flight the plane wants to drop the left wing and role. I can control the amount of role by the amount of back pressure on the stick. I was at 1/2 to 3/4 throttle each time the plane did this. I had to use right aileron to stop the role. Needles to say it is taking the fun out of flying this plane. I have about 8 flights on this plane and did not notice this problem on earlier flights. However I have been taken it easy and have been gradually getting more aggressive with my flying of this plane. I do not have any radio mixing programmed into the radio. I have this plane set up as stick and ruder. I have 25 years of flying models airplanes and have not run into this problem before. I built the airplane myself and am certain that everything is straight but will be checking it with an incidents meter to make sure nothing has changed. I have balanced the plane as recommend in the instructions and have also balance it from side to side. The engine has the correct thrust. I am out of ideas please help. Thanks for taking the time to read this post and offer advice.

balsadust74

My Feedback: (3)

G

andrew66

Im about 80% sure its engine torque that is causing it. You will notice it more at low airspeeds, high power settings and high angle of attack. Also, check the lateral balance. you would be surprised how much better a plane flies when it is laterally balanced.

jvigani

How heavy is it? Sounds like it may be stalling. A heavy plane will have to fly at a greater angle of attack to generate the necessary lift and if you pull back too hard on the stick it can stall and the engine torque will cause the left wing to drop. It's worse at lower speeds.

Lnewqban

Could you explain those three statements a little more for me?
Thanks

jetmech05

dual elevator servos or single? If dual are both servos operating at the same speed and same throws?.....Are you sure there is not a mix accidentally put in the transmitter???? Have you visually checked the control surfaces while on the ground to see if you're getting an aileron deflection with elevator???? What is the rudder doing? Lastly try another receiver and if possible transmitter......I had (key word had) an airplane that wanted to roll right with throttle at idle...after the dust settled found alot of surface corrision on the receiver board...cleaned it up and can not duplicate the problem on the bench...let us know what you find

Gray Beard

My Feedback: (-1)

Check the elevator halves, if one is throwing more up then the other that will do it. If I'm flying mine on high rates and pull back too much on the elevator it will roll out because I have way too much throw set up on high rates. Everything mentioned can pretty much creat a problem. It takes me a while to get a plane into fine trim so it behaves correctly.
If you want you can send me a PM with your email address and I can send you a trim chart that will tell you what to do when your planes is acting odd. Very simple, it tells you to do this and if the plane does that you check this. Just an old pattern trim chart.

balsadust74

My Feedback: (3)

Regarding Inewqban's question
When the role happens I am not increasing my engine's power setting, I am flying straight and level and was pulling up to do a loop or humpty bump which would cause the airplane to role quickly to the left. If I had pulled full up it probably would have snap rolled. Depending on how far I pulled back on the stick would change the rate of speed of the role.

I also noticed on this flight that when I would do a role on the down line that it didn't role on a string, instead it did more of a downward barrel role.

Regarding jetmech05 questions
It is a single servos on the elevator, ruder and ailerons, I built the kit before everyone when dual servos
We did visually check on the ground for mixing and there was not any, I thought I might have a funny acting thumb and this was also found to be working fine. All controls are steady when I move the elevator up.

I believe that all of my previous flights the elevator was set on low rates, when I landed the plane this time I notice that the elevator rate was set on high, so this maybe why I had not had this problem before. However, I didn't feel that I was pulling that much up on the stick. I have done square lops with other airplanes and not had this problem and I wasn't trying to pull up that hard or do this many G's when I noticed the problem on Sunday. How do 3d flyer avoid this from happening?

Please keep throwing Ideas and suggestion at me; I hope to get this problem resolved so I can have fun with this airplane before it roles on me too close to the ground and ends up in the dirt. Thanks again to everyone!

balsadust74

My Feedback: (3)

the elevator is couple with piano wire and there is no flex between the two halfs of elevator

jester_s1

If I am understanding your correctly, you have a consistent roll coupling with your elevator input that will increase with greater input, and that you can actually control with your elevator input. Is that right?

If that's right, the only two ways I could see that happening is if a mix did actually exist (which I know you say doesn't) or your elevator halves aren't moving together. have you checked both sides to make sure that nothing has gotten mushy or come loose? How is the control setup on the elevators?

Edit: The above post about the elevator joiner was made while I was typing this one.

Question: Have you checked the piano wire connections under load to be sure one isn't mushy?

aerowoof

you are experince what is called a high speed stall (accelerated stall) influenced by the extra throw on the elevator when on high rates.
read this
http://www.planeandpilotmag.com/pilo...ted-stall.html

balsadust74

My Feedback: (3)

It was just check and is firm. I have braces on the bottom of the horzontal sab that I added after the first flight as I cracked the sab on landing, I also added some carbon fiber and doublers where the stab cracked. Today the tail was check to make sure everything was straight and true and braces were added to both sides of the vertical stab. When checking the engine is was noted that there was extra right thrust so this is in the prosses of being corrected as I type. Also the airplane was checked again for lateral balance. Would too much right thrust be the problem? It seems like it would cause a role to the right not the left if it had too much right thrust, but my brain might not be working correctly at this moment.

Lnewqban

Unfortunately, a careful review of the incidence and deflection angles with a good meter is the only option you have, as I see it.

Special attention to the symmetry of those angles is important.

Either your left elevator deflects up more than the right side, or the AOA of the right wing is bigger than the left side.

This last thing can be compensated with aileron trim for level flight, but not for high AOA induced by the tail pushing down at your command for a loop.

Another possibility is than the fuse structure connecting the wing and the tail is not solid under load, due to a broken member, etc.

balsadust74

My Feedback: (3)

I have considered the idea of the high speed stall (accelerated stall). If that is the problem and I was not pulling up hard on the stick, how can I resolve the problem so that I can do square loops or 3D flying. I am not a 3D flyer but how do they prevent high speed stall from happening. Since the plane was on high rate I could have been pulling up harder that I realized but at the time I was just pulling up to do a 1/2 cuban eight, the next time was for a loop. Should I try flying it again just on low rates and see what happen before changing a bunch of stuff. Once I realized that the elevator was on high rates I almost decided to fly it again but didn't want to risk a crash until I heard from more experience pilots and problem solved everything possible thing?

DRC1

My Feedback: (10)

Is this your plane by chance?

http://www3.towerhobbies.com/cgi-bin...?&I=LXVVG4&P=7

Or Most likely

http://www3.towerhobbies.com/cgi-bin...?&I=LXJ579&P=0

With a 61FX I suspect it would be easy to have the CG a bit nose heavy. Where is the CG in relationship to the recommended CG?

How much throw do you have in you Elevators? It doesn't take a lot to control the plane. Some of the biggest set up issues is dialing in too much control deflection...High rate for the plane is only 11 degrees, and low rates is only 6 degrees for normal flying (reference Plane's Manual). If you have 51 degrees set up for 3D and try to fly it, it will snap out every time you pull elevator unless you have a lot of Expo or don't move the stick much to fly (not recommended)...High deflection valuesare for controlling the plane in High Alpha manuevers (Hovering, Harriers, etc...)

If this is your problem, then the solution is setting up dual or triple rates depending on your Transmitter...

LLD

gene6029

I agree with aerowolf, it sounds like accellerated stall causeing it to try and snap. Try reduceing your elevator rate to 12-15 degrees. You should be able to fly complete sequences at these rates. Set this up as your low rate/precision flying. Get used to landing with this rate by useing your throttle to control your altitude on final, if not you may run out of elevator and your plane wont flare out nicely. Hope you get it figured out ....Gene

andrew66

try putting a 40 in it temporarily to see if the prob goes away. a 60 in a 40 size airplane is way overkill. After reading all the checks that you have done i am now 99% sure its torque. The same problem happened in the sopwith (WW 1 fighter) they put a monster of a motor in a small light airframe, and the pilots found out that with a very abrupt controll input, the plane would do not exactly what was intended (kinda whats happening with your plane) alot of RAF pilots were killed cause of this, and it also alowed the pilots that learned to use it to their advantage out maneuver the enemy aircraft. I highly suggest that you use a smaller engine.

balsadust74

My Feedback: (3)

LLD,
I have the second one,
I think you guys are right with the accellerated stall, I beleive I kept close to the recommend setting but may have increase them slightly to resemble my sig something extra. I will measure the throws next.

The other thing I though of was when I built the wing it balanced laterally but went I attached the wing to the fuse I had to add weight to the left wing because of the big O.S. 61 hanging off the right side of the fuse, and it is the left wing that is dropping. However, when you put the fuse and the wing together and laterally balance the plane it is perfect.

All this feed back to this post is great. Thanks!

balsadust74

My Feedback: (3)

Regarding a smaller engine in it, I had a .46 in it the first flight and it didn't have enought power. When this plane first came out everyone that was flying them ended up putting 60's in them because of lack of power. I though my .46's had enought to prove the guy with 60's wrong but I was the one in the wrong. If it was torque I beleive that the plane would want to roll when you abuptly add power just like a full size P-51 but I can add power as fast I want to with out any problems. It is only when I pull up elevator that I have the problem and when I have the problem I am not adding power. I am thinking about trying up elevator at with the engine at idle again and see if it still just drops the nose or tries to role like it does at 1/2 to 3/4 throttle. My bet is it will just drop the nose, but I have been wrong before. I have not been flying at full power, yet!

The next thing I am going to try is to see if I have too much up elevator throw.

icegs

Does the plane roll to the left, or does the left wing just drop? If you use a little rudder when you pull up does it go straight?

Torque will only cause a roll to the left as you increase power, if you are at a constant power setting and get a roll, it's something else. Even if your plane is perfectly balanced, and perfectly straight, you could get a bit of a left turn due to assymetric thrust. As you pull the nose up, one prop blade will get a little extra speed, and the other will lose some. This will give you a bit of a left turn that will only present itself at higher angles of attack, or when you increase angle of attack. Using a little rudder will take care of this. An adjustment to the thrust angle could help if you don't want to have to use the rudder. The thrust angle on the plans might not be adequate for your bigger engine.

If you are getting a wing dropping and not a roll to the left, ignore this.

TedMo

You are definitly stalling. Don't recall if you had given the weight but seems like perhaps too heavy or too far back with CG. Main thing though is reduce elevator throw. This is one of the 1st things I check on new maiden, give full up and see what happens. Usually all is well but now and then one will snap to left, reduce elev. throw all is well.

DRC1

My Feedback: (10)

With any plane Static Balance is all good. It gets you in the air safely. However, more often than not final adjustments of CG and even lateral balance is fine tuned in the air (meaning static balance does not equal aerodynamic balance with one variable being your flying style).

I'm concerned about the weight you added on the wing to counter the engine hanging off the right side. It is possible that you put too much weight on the outer edge of the wing which could be contributing to the wing dropping. After getting your throws settled in. Try removing some weight on the wing tip. Once you have a good feel in the air, try flying inverted at 4 mistakes high and push to a vertical (nice easy push) critical that youmake sure wings arelevel. Try this a few times. Does the left wing still drop? If so it most likely is too much weight on the left wing which will cause theleft wing to drop both inverted push and upright pull to vertical lines...

Why 4 mistakes high...? If you are fighting a snap you will want time to recover from inverted...

The best way to go through all of this is by using some of the trim charts that are available. Once you get it close, you will trulyfind flying any plane much more enjoyable.

LLD

balsadust74

My Feedback: (3)

I would say it is more of a wing role than a drop because it was as if I did a sudden turn to the left, the nose held allitude and in some cases gained allitude.

Ray Wasson

I don't know the reason but for example an increase from 12deg. to 15 deg. might cause a stall and snap but increase to 45 deg. and it will do a Wall with no tendency to snap. Also you normally enter a spin by increasing elevator and slowing the plane untill a stall accurs and a wing drops. With 45 deg. or more elevator instead of droping a wing it might decend nearly straight down with the nose slightley high. This is called an Elevator. I don't know why this happens, I just know it works this way.

Ray

jetmech05

I don't think it is a high speed stall....the pilot states that he is barly pulling up elevator......And that he had previous succesful flights....Before the next flight I'd look at the receiver......remember I had a problem rolling with power off...also look at any Y connections.....I don't think you have an airplane problem...I think you have an electronics problem....troubleshoot until found