ddaver

My Feedback: (3)

Any help would be appreciated.

I have a 120 size Edge 540T. It has split elevator halves. They are identical and true. The servos (HS 625MG's)are on seperate channels and mixed using my JR8103. The geometry between each half is identical as are travel. When pulling back on the stick both halves move exactly the same and stop at exactly the same spot using a throw meter. When I apply even pressure on the two halves they act identical (pushrods are short, straight and stiff, very little flexing under extreme pressure).
The plane is balanced to mfgs specs, and flies level upright and inverted. I have not balanced laterally yet, but I did place heavy battery and switch etc on left side to compensate for engine mounted to the right, as I have done in every other plane I have built.
Control surface throws are minimal compared to what this aircraft is capable of.

Now here's the problem, when I apply full up elevator the plane rolls to the right. In a dive it spirals hard and I've been lucky to save it. Even with gentle elevator input she rolls slightly to the right. In a right turn the plane wants to roll over to the right, more elevator harder the roll. In a left turn once elevator is applied she wants to wash out of the bank proportionate to the amount of elevator input. If the elevator halves are not acting in unison, I can't duplicate it on the ground.
What else can be wrong? I have checked alignment of the wing and tail feathers. Engine has 2 degrees of right thrust and flies perfectly straight and level hands free.


Go nuts pontiffs, I'm really scratchin my head on this one as is everyone in my club that has seen it fly.

Thx in advance,

ddaver

bubbagates

My Feedback: (32)

ddaver,

Check that you elevators are moving exactly the same amount at exactly the same time.

Here is how I do it.

Get yourself 2 very straight balsa sticks probably about 12 inches long and 2 clothes pins (spring type is preferable) glue the balsa sticks to the clothes pins and clip each one to each elevator half angling them to meet behind the rudder. They should line up perfectly

Now move the elevators with the transmitter and watch the sticks, they should stay lined up the whole way through the travel in both directions. My guess is the right side is moving quicker than the left so it reaches full travel first causing the roll.

A bad extension, loose extentsion, 2 different lengths of extensions on each half, can all cause this.

throw meters are great for checking total through but they will not show a difference in speed.

ddaver

My Feedback: (3)

Thx for your quick response bubba. And for the tip. As I stated in my original post that is not the problem. Those elevator halves move together throughout the full deflection as if they were one, even under a simulated load (pressing with fingers).

At this point I'm thinkin it's gotta come down to lateral balance and or wing incidence. How critical is lateral balance on a pattern plane such as this?
I have one plane with a camera under one wing and a transmitter antenna stickin out the side of the plane. Besides significant lateral imbalance there is tremendous drag on the left side of the aircraft and with a little trimming it flies straight and true even does basic aerobatics. Granted its a big high-wing trainer type.
I thought about going inverted and pushing full down elevator to see what happens but I'm too scared I may plant this thing, and given the hard ground at our field I fear losing it all. I do not enjoy flying in big slow circles this thing outta tear up the sky but I'm simply afraid of it.

ddaver

bubbagates

My Feedback: (32)

I did catch what you mentioned about the elevators but to me everything you describe points to the elevators being out of sync somewhere in the travel. yes, lateral balance is important. To snap as hard as you are decribing though lateral balance would have to be off quite a bit with the right side being the heavy side.

A warped or a difference in incidence in a wing(s) can most certainly do this.

The horizontal stab could be off, the vertical stab could be off. If the vertical is off then you would be adding rudder trim to have the plane track straight if all else is good.

I would suggest getting a trim chart if you already have not done so and follow it.

I use them on my large planes and it really does help.

CJKling

My Feedback: (1)

ddaver,
Take this beast up 5 or 6 mistakes high, invert it, and then try the inverted roll like you said. If it should go crazy, throttle back and do everything in slow motion. I had a problem like this on a smaller plane, but the elevator halves WERE flexing, however when I would do an inverted loop the same problem did not occur.

Also, the lateral balance is pretty important, especially when you're pulling up with the force of gravity exaggerating every imperfection. Good luck.

Another note, to narrow down the source of the problem, If anything Bubba or I said doesn't help, take the plane into a loop, observe, and then try to correct the problem. Remember the inputs that you need to correct, likely aileron or rudder, and this could help to narrow down what it might be coming from.

Who is the manufacturer of your plane?

michpittsman

My Feedback: (11)

While you watch the elevators what are the ailerons doing?....Jim

CJKling

My Feedback: (1)

It's very doubtful that there is a mix on, he would definately notice that on the ground during a preflight or something like that.

exeter_acres

My Feedback: (2)

no...you might not.....

There are mixes that are 1 or 2% deflection that you can't see unless you are staring directly at the surface, but make a big difference in the air...

the one thing I didn't see anyone mention is Too much elevator throw... aerobatic planes do not need much delection at all..
I have a smaller Edge (.90 size) and was amazed at how little deflection it needed...

Something else to look at ..

Blue_Moon_

check the joiner wich hold the two ailerons togheter. probably its to weak and need to be replaced by something stiffer.

good luck!

Bax

My Feedback: (11)

Are the servos holding? You may have equal deflection on the ground, but aerodynamic pressures could keep both halves from deflecting equally. You'll notice this if you have rolling behavior in both inside and outside maneuvers. The model would roll one way upright and the other way inverted.

ddaver

My Feedback: (3)

wow look at all the advice!!!!!!! Thanx Guys.
Ok lemme respond

Bubba: I know it seems like it awtta be there but trust me them 2 halves move together in perfect unison throughout the entire arc. I use the trimming procedures from Bolly http://www.bolly.com.au/book/

CJKling: Thats my next option but i'm scared as hell that even at altitude I may not be able to save it given that the problems come in with application of the elevator control. It is a GiantScalePlanes Edge 540T with a 120 4stroke. I'm an excellent builder and really took my time everything is square and true. I have seen GSP take a beating on these forums but this model seems pretty decent (exc. covering material sucks). I made some reinforcement and modifications like upgrading the hardware and using bolts and blindnuts instead of screws etc. nothing that would cause this problem tho. And of course now all the guys at my club are aware of this problem and they are not willing to fly it.

michpittsman: The ailerons do not move. nor does the rudder. Only mix i have using the ailerons is the standard mix since both ailerons are on diff channels that way i can trim and set their travel and differential.

exeter acres: you may be on to something, but remember the undesirable roll happens to a lesser degree at small movements as well.

Blue moon: I have no idea what you are referring to. if you meant elevator halves, they are not joined they have seperate servos driving each side.

Bax: Yeah I thought of that right away so i hold the 2 elevators back with my fingers as i moved the stick and they both flexed about the same and I hadda really push hard to get em to do that. I think the balsa or hinge will snap 1st.



I'm gonna do the lateral balance and check the wing incidence and give her another flight this weekend weather permitting. I will report any findings.

Thx again for all yer help any other suggestions are certainly welcome

ddaver

Blue_Moon_

join them togheter then, and only use one servo. Easy. Voila!!!

bubbagates

My Feedback: (32)

ddaver,

I apologize. I did not mean to imply that you didn't know what you were doing so if I upset you please accept my apologies. I will say that I have responded to this same question time and time again and it has in most cases always been travel or lateral balance.

Too much throw will cause this. I have the VF Edge and it will snap out to one side, but never the same side (lateral balance is ggod) if I get too much throw. Yep I understand it's tons smaller but every bit as efficent.

I really would like to hear what you find out. I keep a running document, actully many documents, for the most common problems I see here on RCU and I would like to add to it if it ends up being something else.

onewasp

Unless it is off a ton lateral balance has little to do with it.

Check out the following qupote from Chip Hyde------
There is a tremendous amount of misinformation on this subject-------published here as a matter of fact------it is simply wrong.
http://www.rcuniverse.com/forum/m_23...anchor/tm.htm#

CJKling

My Feedback: (1)

Good Luck daver, I am too very interested to see what you find out, see what corrects it, etc. An Edge is fully capable of flying in circles, but it is sad to see one that is CONFINED to flying in circles. Again, good luck.

ddaver

My Feedback: (3)

Blue Moon: I'm sure that you are just trying to be helpful. But, joining the halves is not possible on this model.

No problem bubba, not at all upset, only frustrated with this situation. I'll keep you posted, you've been very helpful.

Onewasp: I have never balanced a model laterally, and as I described I have a plane thats not only significantly out of lateral balance it has tremendous drag on the left wing yet still flies straight after trimming. Nonetheless I will balance this one laterally if for no other reason than to eliminate that as a cause of my problem.

I went to the big bird fly-in in Rockford yesterday, so I didnt get any flights in, maybe today. I'll keep all posted.

ddaver

bubbagates

My Feedback: (32)

I missed this part earlier. How much airleron trim is needed?

I'm sure you know if it's significant then you will get all kinds of drag. This could very well be lateral balance if the trim amount is significant

I await to hear the results...

destructiveTester

Hi,

here are some other things you could try

1. swap elevator servos. If it still snaps to the right then you know that tail is the wrong place to look.

2. swap aileron servos (move right servo to left and left servo to right) - If the left hand aileron servo can't handle load then it might be deflecting up which would mean that the right hand wing would stall at a lower angle of attack.

3. you've probably done this already but check the wings are made true and are identical. I had to pension off a wing yesterday because the control hinge line web and peeled apart causing the upper skin on the left wing to lift up. This caused the model to snap to the right very hard with slight elevator deflection (5-10 degrees of elevator) at cruise speed. I would never have believed the nature of the airfoil 70% back from the leading edge would be significant but I guess if your wings aren't identical strange things can happen.

what's the wing loading of this aircraft? (can you post all up weight, wing area or root, tip chord and span?)

don't give up!

EscapeFlyer

My Feedback: (1)

What you are experiencing is a stall. On these airplanes, with lots of meat in the elevator, it is very easy to put the wing past its critical incedence where there are then 3 forces working on the airplane when the lift has been destroyed. They are:

1. Engine torque. The airplane will roll the opposite direction of the prop. The only way to counter-act this is opposite rudder-or sheer power. I would recommend you try rudder.

2. Gravity. The plane is no longer flying-it's coming down!

3. Forward momentum. Inertia throws the airplane forward in a downward arc.

There aren't many ways to fix this other than utilizing rudder and/or great amounts of power. Cg affects this as well as the simple design of the wing. That is why some wings are proned to the stall more so than others, but all wings will stall when they are pushed past their critical incedence- where the flow of air over the wing is no longer laminer and too disturbed-destroying lift.

These airplanes literally have to be "flown" through every manuver, and a HUGE amount of power can be utilized to overrule "simple laws of physics."

Try using opposite rudder to counteract the engine torque to see if that helps you.

ddaver

My Feedback: (3)

Bubba I was referring to a Sig Kadet Senior that I mounted a camera system in. Camera under left wing although quite small, it is mounted on a servo platform that allows for pan and tilt.

destructiveTester: Read on, several of your suggestions have been done. It's an ARF but the tail feathers are flat and they check out as straight and true. The wings also appear straight, true and free from warpage, visually atleast.

ILikeBipes: I think that you have hit it on the head. This plane has flight characteristics that are just new to me. I have read every post I can find regarding the edge and its flight characteristics and even the big guys flying the 40% Cardens etc. mention some of the same things that I am seeing.

Here's what I've done:

*** I removed all servo extensions and soldered servo extension wires the proper length to reach the receiver. The only push on servo extensions are from the receiver to the wing servos (easier to connect than trying to plug into receiver every time).
*** Remounted the receiver, battery, voltage regulator and antenna. By separating each of these components as far as possible I have surely eliminated any chance of internal interference.
*** Reduced the elevator travel and put in 60% expo
*** Put in 60% expo on the ailerons and rudder
*** Rebalanced, front to back and side to side, this thing ain't off as much as a grain of rice from Mfg's specs. The lateral balance required 1/4 oz. on the left wing tip after all that!!! Pfft!!!

Results????? It's better. It's apparent that speed must be kept up to keep the model responsive. Tracks well and cuts a fairly stiff wind with ease.

Ok so now it climbs when I roll inverted (after trimming for level flight). Take off requires a longer than usual run........Thats right the wing incidence must be wrong!!!!!!!!!! I never checked it during assembly for 2 reasons. Number 1 its an ARF, isn't that something thats done at the factory? And secondly the wing saddle was such a nice fit it required no shimming on my part, pretty nice I thought.
So now i will begin the arduous task of shaving and shimming the wing saddle and turtle deck to get it right. (I'm guessing 0-1 degree positive). After that I will fly her again and if I can't get comfortable I will remove the Engine and radio and donate it to the school or library or someplace to use for decoration. If she does fly well I will rip the covering off and recover with ultracote or monocote, cuz the covering thats on it can only be described as pitiful.

I am not going for the longest post in RCU history but I am going to finish with my assessment of this "Edge 540T 72" 120size" from GiantScalePlanes

Hits:
+ Instructions and plans (very short and to the point, this is good since they don't match the materials in the box and they are written in chinese!)
+ Cheap as hell 120 size edge for just under $200.

Misses:
- Wing Incidence off, Among other things, most intermediate pilots and beginner builders will have their hands full with this little beauty.
- Poor hardware (one of the control links failed on maiden flight nearly cost me the airplane). Wheel pants are a joke, admittedly I did laugh when they cracked on 1st flight.
- Covering Material does not shrink and adhesive does not re-activate making wrinkles and bubbles impossible to remove. trim covering is like plastic crepe paper and in only 8 or 10 flights every piece has lifted or flown off. color of cowl does not match covering (it's red, white and blue, the white is close, but they dont even line up).
- Instead of dowels the turtle deck mounts using brass fuel tubing pieces. I replaced them with hardwood dowels after they both came loose and became permanently sealed in the fuselage. Nice little rattle can be heard if you shake the plane. LMAO If I keep it I will cut a door and remove them.
- CA type hinges are included with the kit, yet an addendum to the instructions (written in english) says not to use them. So why put em in there? There are atleast 10 extra parts including a little aluminum pin about 1/4" in dia. I have no idea what it's for.
- Firewall and main gear mounting areas required some beefing up IMHO.
- Flies like POS!!!

ddaver

EscapeFlyer

My Feedback: (1)

Checking wing incedence was a good idea. Have you tried rudder on high rates? I'd fly it the way you have it now on low rates, and use your original settings for high rates. I'd only use high rates for those "special" manuvers.

ddaver

My Feedback: (3)

Most of my flights to date can best be described as "White-knuckled". Basic immelmans, cuban 8's, rolls and large inside loops, with lots of procedure turns and just flying the circuit. I will never forget that 1st immelman turn when I eased back on the stick and she didn't pull out fast enough, so I yanked back on the stick and she went into a spiral towards earth. Mostly I remember the save I made and the gasps from the gallery.
All of my landings have been great but quite often I've had to make several passes to line up, as you would expect with a new plane.

This was my graduation from sport planes into pattern aircraft. I am hoping to learn more with this plane, including perfecting rudder skills and the use of dual rates for different maneuvers.

I have very good hand-eye coordination, but I would describe my flying skills as maybe a 6 or 7 on a scale of 1 to 10 with a 10 being competitive fliers.

Well, back to the shaving and sanding

bubbagates

My Feedback: (32)

ddaver,

I've been away from this thread for a few days and just got caught up on it.

Wow, you have really researched this one pretty well and if the incedence doesn't correct it there is not much left to verify short of the fuselage having some sort of "warp" to it.

For your sanities sake, I hope that the incendencetakes care of the problem. I haven't heard of this particular plane having problems like this so maybe a search on here and other forums might be in order. I'll do that as time allows and if I find anything worth while that has not been considered already I'll post it here. But as I mentioned, with everything you have already done, there is not much left.

britbrat

Just to make you feel better, I have a very old (14 yr) Florio Flyer that does exactly that. It has been through the mill so many times that it just ain't straight any more. At some point in its violent career it started snapping with full elevator & I couldn't fix it. It is still alive & well today many years later. The case of "snaps" is usefull for doing the most violent snap-rolls that I have ever experienced -- absolutely wild horizontal flat spins, so fast that you can't follow them. I just avoid hard elevator applications near the ground.

bubbagates

My Feedback: (32)

ddaver,

I have only found this one thread covering that plane so far. It's kinda old but my specific concern as raised in this thread is wing loading and a quick look on GSP's web site shows only 868 sq inches of wing area so my immediate thought is how heavy is your plane.

As far as I'm concerned, 868 is kinda small for a 72 inch wing span. But again that's just my opinion

http://www.rcuniverse.com/forum/fb.asp?m=472049