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Scary maiden

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Scary maiden

Old 07-29-2008, 04:23 PM
  #26  
Brokenprop
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Default RE: Scary maiden

I really appreciate this discission. I used the link above to the CG calculator. If it is to be considered, the recommended CG for this wing planform is 3.95 inches from the LE for 30% and 3.375 for 25%. Neither of these is anywhere near the 5" specified by the instructions. Craig-RCU was OK with his at 5".

I have several chargers and have discharged this pack on an AccuCycle to check it's capacity. However, I did not do a range check with the engine running as Inewqban suggested. I will do that before I attempt aviation again. The other thing that is unknown is the reliability of the receiver. I got it from Condor Model. Not the one in Canada. It is one of those 72 MHz units that is suppose to recognise the transmitter and be very immune to interference. I haven't had it in a plane before.

Today I purchased a FAAST reciever for the plane. That should eliminate at least one unknown.

I thinking that a full tank of fuel should have off set any tail heavyness that early in the flight.

I have increased the throw on the elevator and removed a couple ounces of weight from the tail. I'll try it tomorrow if it doesn't rain.
Old 08-15-2008, 07:39 PM
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Default RE: Scary maiden

Sorry for the delay. I flew the F4U today. I've been procrastinating, anticipating a repeat performance. I took extra trash bags to the field with me. I know I spent too much time tuning the engine. Finally couldn't put it off any longer, summer is short. Took a last photo of the bird with the phone and said goodby.

Take off was cross wind and needed a little more elevator than I expected to keep the prop off the ground. That little bow before you catch it isn't pretty.

The balance of the flight was uneventful!!! The landing was graceful with plenty of float and nothing nasty.

The major change here was the removal of 5 1/2 ounces of lead from the tail. That moved the CG forward 1 1/2" to a position 3 1/2" back from the leading edge. The plane went from totally unflyable to quite docile.

I have a really old Royal Corsair kit that is identical in size, so just for comparison, I fought through the mildew and unearthed the 30+ year old plans. Specified CG is 3 1/2" back from the leading edge.

Someone had to know that at Horizon. Ignorance is expensive.

Thanks again for the support.
Old 08-15-2008, 11:21 PM
  #28  
Craig-RCU
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Default RE: Scary maiden

I'm glad to hear that things went well for you. 3.5" if the furthest forward that I've heard anyone balance a H9 Corsair. You might try moving the C.G. aft 1/8" at a time to see if you like the flying characteristics better or worse. The Topflight .60 size Corsair is also comparable to the H9 Corsair and the Top Flite is balanced at 4.25" http://www3.towerhobbies.com/cgi-bin...&I=LXHU80&P=ML The large prop that you are turning may have some unique aerodynamic effects that require a more forward C.G. than most.
Old 08-16-2008, 07:46 AM
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Default RE: Scary maiden

It's amazing how differently some ARFs work for different modelers.

I'm flying my H9 with the CG around the 5.4" location. It's an excellent flyer. And handles on the ground really good for a taildragger model with it's wheels so far aft.

The CG computations showed a range of 4.3" to 5.4" for me. And the flying field that airplane will taxii around on most of the time is anything but smooth, so it's CG was located as far aft as possible. I knew it'd be flyable although it's elevator would be sensitive, and the elevator pushrod has been moved out on the horn a step.

It is very interesting that the response you saw to begin with was so odd. To not respond to input for so long and then suddenly respond really doesn't sound like a trim problem. But what the heck, you've got it flying and you can't argue with success.
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Old 08-16-2008, 09:13 AM
  #30  
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Default RE: Scary maiden

If I were a betting person -I would bet tha a LOT of the problem had to do with the physical servo/linkage /elevator setup
A good test is to see if two clicks of trim -either way- from center will make some discernable movement in the elevators. also with new GOOD radios - it is almost impossible to fly them easily without expos - the tx/rx and servos now available respond like trained rats - -making shaky or quick stick movements into wild elevator movements.
On my DX7 I need typically 50-70% expo in elev- -on a model such as th H9 Corsair - I would start with 25% expo and do a hi/lo throw setup. (my X9303 needs l a bit less expo)-
Some claim they don't use expo-
that's possible - -but it infers that the setup is either very vague -or slow -or old -or weak -or tiny throws are all that is available.
Old 08-16-2008, 11:53 PM
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Default RE: Scary maiden

Craig, granted, the 18-12 prop may be influencing the behavour of the plane. I will try moving the CG aft, an 1/8" at a time, because it is difficult to taxi in the grass without nosing over. As for linkage, the Hitec servos are whining appropriately, determined to hold position. There is absolutely no detectable (without instruments) slop.

When forced to switch from my Kraft single stick to two sticks years ago, I hated it. Neutral is difficult to feel with the soft springs in the gimbals. My solution was stronger springs. I have tried some expo on a couple of "3D" planes and feel like the radio isn't working.

I can't appreciate why, after systems have been perfected to track your movements like a tick on a dog, you would want to program them to respond like an old galloping ghost system. That's just my feeling, of course. That puts me in the minority. It also puts me at a disadvantage when I have to test fly others planes for them and they hand me a box with "wimpy sticks". I've kind of gotten used to it, but I still don't feel as connected.

Dick, I know what you are saying, but I haven't gotten the "shakes" during a flight in a long time. That's sorta too bad too, that was part of the fun, I think. I feel a little jealous when I offer a guy his transmitter asking if he is ready to take over and he says; "Wait till I quit shaking."

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