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Hangar 9 P47 20cc Flight Characteristics

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Hangar 9 P47 20cc Flight Characteristics

Old 08-26-2020, 09:28 PM
  #1  
Fireflite82
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Default Hangar 9 P47 20cc Flight Characteristics

Hello, is anyone on here flying a Hangar 9 20cc P47 running a larger than 20cc gas engine?

I bought this ARF and threw a 26cc RCGF motor with a wrap-around pitts muffler.

From day one it flew as if it was too tail heavy. The airframe, with an empty fuel cell, was balanced at the recommended 4.25" being a touch nose heavy.

Nose weight was added from day one as well to achieve balance on the bench.

I exhausted all trim on my elevator. It flew like crap almost uncontrollable. Before the second flight, I rechecked everything on the airplane. I mechanically added a little nose down and brought my trim back to center. I added a little more nose weight.

The second flight same issue but not as bad, still exhausting my trim by 75%. Although this time I nose over on the rollout.

I again, inspected everything on the plane and this time I went in and adjusted the sub trim. On all subsequent flights I am able to fly controlled but never hands-free for more than a few seconds.

This isn't sitting well with me. I want my control surfaces as neutral as possible.

Now I have a feeling that with the added nose weight is in fact attributing to my nose overs. I can achieve a good glide slope slightly nose down with about 60 degrees of flap. I can grease the landings, but the dang rollout. With every landing, once I touch down, I am walking a fine fine line of trying to hold just enough up elevator, throwing my flaps back up, and trying to keep it level so that I don't get airborne again.

Thinking about it, if I didn't have so much nose down on these control surfaces that may make it a little easier to roll out and not have to pay all my attention to finessing the elevator.

So again none of this is sitting well with me and I was wondering if perhaps I need less nose weight (getting well back to being neutral) and needing more right and down thrust angle?

I've decided to post a thread because almost all H9 P47 20cc threads I found are running electric setups. Any advice from any experienced pilots would be greatly appreciated!!
Old 08-27-2020, 09:26 AM
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Lifer
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The first question that comes to mind is how much elevator throw are you using? My friends have several of these planes and they all fly on the low rate setting. As well, the balance point is at or near the recommended rear location. There is little to no nose-over tendency. They taxi with high-rate elevator but switch to low for takeoff and flight.
Old 08-27-2020, 09:30 AM
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Fireflite82
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Originally Posted by Lifer View Post
The first question that comes to mind is how much elevator throw are you using? My friends have several of these planes and they all fly on the low rate setting. As well, the balance point is at or near the recommended rear location. There is little to no nose-over tendency. They taxi with high-rate elevator but switch to low for takeoff and flight.

I have all of my control surfaces dialed in to the recommended throws or of the manual. I'm not at home right now but if recall is something like 12mm/15mm low/high. I do the same low rates for take off and flight and high for everything else.
Old 08-27-2020, 09:45 AM
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Lifer
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Sometimes you can have the balance and throws perfect and the damned thing still wants to nose over. At that point, I recommend you cheat.

Put some washers in the rear retract mounting holes between the retract body and the bearers. 1/8th to 3/16ths is a good start. It will angle the gear to the front and reduce the unwanted tendency. Just don't tell anybody.......
Old 08-27-2020, 09:49 AM
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Fireflite82
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Originally Posted by Lifer View Post
Sometimes you can have the balance and throws perfect and the damned thing still wants to nose over. At that point, I recommend you cheat.

Put some washers in the rear retract mounting holes between the retract body and the bearers. 1/8th to 3/16ths is a good start. It will angle the gear to the front and reduce the unwanted tendency. Just don't tell anybody.......

Lol, that's a good idea. I laugh because "don't tell anyone". I honestly beleive right now that I may have to much now weight, but that's only due to it wanting to nose up during flight which causes me to beleive that I don't have enough downward thrust angle
Old 08-28-2020, 03:04 AM
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Old Erkki
 
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Default Think again

Lets take hypotethical situation that you want your plane to fly so that it flies 90 degree angle tail up (yeah yeah I know it is not possible). But in that situation you have to have engine 90 degree up and stabilizer 90 down and wing 91-92 degree up. So if you add engine angle more down it will pull nose down and you have to compensate that with greater angle of attack on the wing. So tail drags down

How does your plane fly reversed. If it tries to gain height (hands free) then thrust is way too much down.

My thougts

Old Erkki
Old 08-28-2020, 03:27 AM
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sensei
 
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Originally Posted by Fireflite82 View Post
Hello, is anyone on here flying a Hangar 9 20cc P47 running a larger than 20cc gas engine?

I bought this ARF and threw a 26cc RCGF motor with a wrap-around pitts muffler.

From day one it flew as if it was too tail heavy. The airframe, with an empty fuel cell, was balanced at the recommended 4.25" being a touch nose heavy.

Nose weight was added from day one as well to achieve balance on the bench.

I exhausted all trim on my elevator. It flew like crap almost uncontrollable. Before the second flight, I rechecked everything on the airplane. I mechanically added a little nose down and brought my trim back to center. I added a little more nose weight.

The second flight same issue but not as bad, still exhausting my trim by 75%. Although this time I nose over on the rollout.

I again, inspected everything on the plane and this time I went in and adjusted the sub trim. On all subsequent flights I am able to fly controlled but never hands-free for more than a few seconds.

This isn't sitting well with me. I want my control surfaces as neutral as possible.

Now I have a feeling that with the added nose weight is in fact attributing to my nose overs. I can achieve a good glide slope slightly nose down with about 60 degrees of flap. I can grease the landings, but the dang rollout. With every landing, once I touch down, I am walking a fine fine line of trying to hold just enough up elevator, throwing my flaps back up, and trying to keep it level so that I don't get airborne again.

Thinking about it, if I didn't have so much nose down on these control surfaces that may make it a little easier to roll out and not have to pay all my attention to finessing the elevator.

So again none of this is sitting well with me and I was wondering if perhaps I need less nose weight (getting well back to being neutral) and needing more right and down thrust angle?

I've decided to post a thread because almost all H9 P47 20cc threads I found are running electric setups. Any advice from any experienced pilots would be greatly appreciated!!
So I ask you, have you flown a 45 degree inverted up line at half power to see how the airplane reacts? If not you have no idea if the c/g is right it not. That is the first thing you do. If the airplane pitches up sharply while inverted when you release the sticks, it tail heavy, if it pitches down when you release the sticks, its nose heavy. What it should do and what you should balance it to do is slowly ark towards the ground while inverted from a 45 inverted up line, once you have achieved that, the c/g is good and you can begin to move on to thrust changes and so forth. Believe it or not an airplane can feel very pitch sensitive when nose heavy, I have experienced that years ago on a friends airplane.

Bob

Last edited by sensei; 08-28-2020 at 03:35 AM.

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