queasyflier

My Feedback: (6)

I bought a very nice VectorFlight Edge 540@swap meet recently. It is powered by a powerful, yet heavy YS FZ.91 FS. Upon trying to balance the airplane (inverted as per suggested balance from LE) I found it to be quite nose heavy. I noticed that the previous owner had set both ailerons a few degrees up from neutral. Was this an attempt to compensate in flight? I would like to keep this engine, although swapping it for a 2S such as an OS.91 would save me nearly 1/2 lb!
I have not flown the plane yet, but am concerned about the dreaded "sudden snap" syndrome with a little too much elevator or "stall" on slowing down for landings. Any advice?

AA5BY

I've a smallish Edge 540 of 59 inches and with the recommended CG, it was very sensitive on elevator and would balloon when slowing for landing and require down elevator to land and I hate having to give down elevator to land. Running the CG calculator, showed I could go forward with the CG from the recommended and I was much happier. The elevator sensitivity reduced and the ballooning has all but been eliminated.

As to the ailerons being trimmed up, my guess is that it was an attempt to trim out knife edge tuck or deal with the ballooning when slowing. Mine was tucking to the gear pretty bad initially during knife edge, but that has gotten better with a more forward CG. Right now, I'm a half inch forward of the recommended CG and considering going more as a bit of ballooning remains and a slight bit of gear tuck remains during KE.

The more forward CG, allows setting the elevator throws to the recommended numbers as they were very hot on the first flight.

I should also say that I'm balancing upright and have not checked to see if an inverted balance produces different results. The recommended CG might be ok for an inverted balance, but Seagull only says, balance at the wing tips hence why I didn't use the CG machine.

ahicks

My Feedback: (2)

Advice - set it up per your best guess, and prior to maiden flight landing, slow it down (at 3 mistakes high) and see what it does. If ugly, cool it on that landing and change as required prior to next flight. Repeat until completely trimmed, flying "with purpose" until you get there.

Re: the engine, I'm performance oriented, could care less about the "4 stroke sound". For me it would be a call regarding an engine to get me to the performance level I'm expecting from the plane. All the while realizing there's always going to be compromises.....

speedracerntrixie

My Feedback: (29)

I would suggest going a bit deeper here. I very rarely buy an airplane already built but when I do I measure it very carefully. Before setting it up I will know the wing and tail incidences and the thrust angles. In most cases they need to be corrected. As for your ailerons being up, I agree that it could have been used to correct knife edge. The result of a nose heavy airplane with elevator trim to compensate then having the ailerons up would be an airplane that flys quite heavy. The reason for that is the reduction in wing lift and force being applied to the stab. Not to mention it would have been flying in a nose high attitude. If it were me I would measure and correct any incidence, set the CG to 30% of MAC and go fly. After initial flights adjust as needed. You may have to move equipment around a good deal to get balance. I have had to put RX batteries in the tail on several models, not a big deal. The YS 91 is a real sweetheart of an engine and will out power most 2 stroke 91 engines. They do tune slightly different though, allow 20 seconds after start up for tank pressure to build before going to full throttle and always set the needle a bit more rich then what you are used to. Good luck.

foodstick

If it ends up being to nose heavy you can always mount your receiver pack back further. I actually have a few 90 / 120 sized arfs that I put a gas engine in.. So I mounted the receiver packs underneath the stabilizer, thru a hatch.. balanced without adding weight !

chuckk2

A "little bit" nose heavy is one thing, more that that causes no end of trouble!
If it's nose heavy with no fuel, it's just going to be worse with full fuel.
I have a fairly popular ARF electric powered "trainer' that had a reputation of being nose heavy.
Turned out that this one was quite tail heavy. Evidently, the factory build used more robust (heavier)
construction. I was faced with adding quite a bit of weight to the nose, or (Light bulb on!)
relocating the wing to the rear. (About an inch as it turned out.)

BMatthews

The Edge design has a fairly radical amount of wing taper so it will tend to want to tip stall if you're not careful. I suspect the previous owner angled the ailerons up a little to try to simulate a little washout in the tips to aid the issue.

It won't do anything for compensating for being nose heavy though.

The best way to avoid tip stalling on landing approaches is to ensure you use very small control inputs and a little patience when slow and close to a stall.

speedracerntrixie

My Feedback: (29)

Can't say that I can agree with this. Yes the Edge has a fair amount of taper but the leading edge is straight. This makes for a very stable wing planform. One of the reasons that most Red Bull race teams fly the Edge. Over the years I have owned several of them and none showed any signs of being snappy. In fact the one I flew in IMAC advanced class for 3 years was a bit to stable of an airplane as it had to be forced into spin entries.

A very nose heavy airplane will want to pitch towards the canopy in knife edge. Raising the ailerons could be a fix for this. It's not the correct fix but it can be a fix if ones preference is slightly nose heavy and ailerons are brought up a half degree or so. Most Edges have close to full span ailerons so not really any washout affect. I'm afraid that the fix for this airplane is to get the CG in the 30% range.

AA5BY

My Edge experience is limited to one small 59" model and I've not found it snappy, though have read that others had but wonder if they were rather describing elevator sensitivity as mine was very sensitive on elevator with the recommended CG. Mine was tucking to the gear on KE and elevator sensitive and I've been trimming CG forward and it has been helping both to ease the sensitive elevator and reduce gear tuck. The other issue that was quite pronounced was that when it slowed, it would balloon and that also was lessened with a more forward CG.

The manufacture suggested CG was at 7.5% static margin and I've moved the CG forward to 12.5% static margin and all seems better there, albeit before the trim is nailed down, 15% will be tried..

BMatthews

Speedracer, I suspect you might have hit the nail on the head with the reflexing to aid knife edge flying.

And truth be typed I was thinking "Extra" when I posted the first reply. Looking at pictures of the Edge design clearly it's not as radical a taper as the Extra.

Or... Something that just occurred to me. It would not be the first time someone took the advice of someone else in a case where it was the wrong advice. We read so much about how models with outboard "barn door" ailerons can be tamed with a little aileron reflex to simulate washout that it's possible the previous owner took that knowledge, despite not applying in this case, and set the ailerons like this in the mistaken impression that it would help. Without knowing the previous pilot's flying ability, knowledge level and the flying characteristics of that particular version of the Edge it's hard to say one way or the other.

speedracerntrixie

My Feedback: (29)

Agreed, on barn door type ailerons re flexing them up does in fact work. Locally once a month a group of us get together to race GP Spitfires. These have a span of about 38" and can be either glow or electric powered. We power them with .25 FX engines. The first time I flew mine I quickly realized it was a snappy little bugger when I tried a tight pylon turn. Bringing both ailerons up two clevis turns cured the snap. An aerobatic model with full span ailerons would be a different animal.