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Hitec, how to program down elevator with low throttle

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Old 07-02-2012, 07:40 AM
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wkevinm
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Default Hitec, how to program down elevator with low throttle

I have a couple pylon racer designs that go nose high when I cut fuel for landing. This was made very annoying and difficult at the last race where we had high winds aggravating the situation, I had to push the stick nearly 3/4 down to keep the nose down and speed high enough for a good glide speed. Flying a dead stick landing approach pushing the stick is not easy, I prefer to pull to keep the right glide.

These planes have no throttle control, rather you pinch the fuel line to stop the engine. Due to the airfoil used (all are 0,0,0 incidence) several designs of racers will go nose high on engine stop from near 200 mph.

How is the best way to mix the elevator so it goes to a slight down when the throttle is taken to 0. I had this programmed in an Eclipse several years ago for a q500 design but never figured out how to program into the Aurora.

Thanks in advance for any help.

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Old 07-02-2012, 08:58 AM
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Scar
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Default RE: Hitec, how to program down elevator with low throttle

Sounds to me like you have too much engine down thrust. When you cut the power, you lose the down thrust.

If that's it, put some shims under the bottom screws on your motor mount, to tilt the engine up. That may take a couple of different thicknesses to find the right one.

Good luck
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Old 07-02-2012, 07:04 PM
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wkevinm
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Default RE: Hitec, how to program down elevator with low throttle

Thanks scar for the advise but the incidence is 0,0,0... 0 degrees tail, 0 degrees wing, 0 degrees motor. The reason for the change in pitch with the power taken away is the airfoil and wing. I have had different racing airplanes do the same. The original Neme Q did it (CNC molded composit), the Sweet V does it slightly, My own molded Q500 with a shoulder wing MH17 airfoil did it. Many pilots program in down elevator as they cut throttle to compensate. I was looking for someone who had experience with mixing throttle and elevator, I'll figure it out but was trying to find a short cut.

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Old 07-03-2012, 04:38 AM
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Default RE: Hitec, how to program down elevator with low throttle

The radio will do it but if you are having problems - just program a flap switch to add downtrim and then hit the switch when engine cuts
my radios (not Auroras) have three position flap switch- which in this case ,could be used for various landing trim setups -when mixed with elevator
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Old 07-03-2012, 07:24 AM
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Default RE: Hitec, how to program down elevator with low throttle

I'd just p-mix the throttle to elevator with a 7-point curve (P-mixes 6,7, or 8.) This way you can have the exact amount you need at any throttle position.

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Old 07-03-2012, 07:36 AM
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Default RE: Hitec, how to program down elevator with low throttle

Sounds like the best approach for you!
On 2meter pattern planes , the downline trims are commonly addressed in similar fashion
I just hand fly everything (learned the old way) but the mixes as described are "the way" to do it for many fliers. I call em switch flippers -
My mentor long ago never even trimmed his models - I said why not?
he said - I just add what is required .
He flew and instructed full scale choppers - fixed wing - models in mode 1 or two-
Not many guys that good at it.
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Old 07-03-2012, 10:10 AM
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Default RE: Hitec, how to program down elevator with low throttle

race planes have pretty much two throttle positions - on, and off..

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Old 07-03-2012, 04:08 PM
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Default RE: Hitec, how to program down elevator with low throttle

I ended up programming using P-Mixes, but did not assign to a switch so the mix would be whenever I shut the engine down (using the throttle control). I have attached picture of setup on TX.

thanks to all that responded.

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Old 07-05-2012, 03:25 PM
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Default RE: Hitec, how to program down elevator with low throttle

Going nose up is one thing, nose up and a stall is another. I'd guess that the plane is a bit tail heavy when low on fuel.
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Old 07-05-2012, 05:44 PM
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Default RE: Hitec, how to program down elevator with low throttle


ORIGINAL: chuckk2

Going nose up is one thing, nose up and a stall is another. I'd guess that the plane is a bit tail heavy when low on fuel.
Typically the prop location when not running , creates a drag which is "nose up" common when thrust line is above wings
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Old 07-13-2012, 10:05 PM
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Default RE: Hitec, how to program down elevator with low throttle


ORIGINAL: chuckk2

Going nose up is one thing, nose up and a stall is another. I'd guess that the plane is a bit tail heavy when low on fuel.

Actually the fuel tank on most racers are bladder tanks on the CG to prevent CG changes from full to empty. You will find racing airplanes are very accurately balanced for lateral and sometimes aft cg to allow for the right characteristics in closed course high speed flight.

This event occurs on race planes that are trimmed at high speed, often set with a slight noze down (for knife edge control of pitch, and another topic). This appears to occur on shoulder wing as well as low to mid wing planes, seems to be airfoil dependent. The original Neme Q with a laminar and reflex airfoil (I think thats what they called it, refering to the trailing edge profile).

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