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Author Topic: Electric Arf Nobler  (Read 2570 times)

Offline Tim Stagg

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Electric Arf Nobler
« on: September 21, 2010, 03:07:41 PM »
Guys,

I have about 8 flights on my nobler and am in the process of working out some trim bugs. The plane seems to hunt in level flight but it is a gradual hunting, I just cant seem to get it to stop.
Balance is correct according to the plans, the control response is fine although it is more sensitive in the outside maneuvers than inside.

The control response seems soft around the neutral point almost a little spongy if you understand what I am describing.

Changes made to the plane beside the obvious electric power:

Adjustable lead outs, weight box, ball links on control system, carbon pushrods. Control system is relatively tight with only a small amount of play.

Any suggestions of where to start would be appreciated

Thanks

Tim









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Tim Stagg

Offline Dick Pacini

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Re: Electric Arf Nobler
« Reply #1 on: September 21, 2010, 04:16:45 PM »
Are you sure your motor/engine/powerplant (whatever you call it) doesn't have any up or down thrust?  Are you sure your stab incidence is 0?  Are your flaps and flippers in total agreement at neutral?
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Offline Bob Reeves

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Re: Electric Arf Nobler
« Reply #2 on: September 21, 2010, 05:55:07 PM »
Hi Tim,

If you are sure the wing and stab incidence is at 0-0, couple degrees of motor down thrust won't hurt and might help. Start dialing in down elevator with the flaps at neutral. Start with the bottom taper level with bottom of the stab and don't be afraid to dial in a little more if you need to.
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Offline Dick Pacini

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Re: Electric Arf Nobler
« Reply #3 on: September 21, 2010, 06:00:06 PM »
Quote from: Bob Reeves on September 21, 2010, 05:55:07 PM
Hi Tim,

If you are sure the wing and stab incidence is at 0-0, couple degrees of motor down thrust won't hurt and might help. Start dialing in down elevator with the flaps at neutral. Start with the bottom taper level with bottom of the stab and don't be afraid to dial in a little more if you need to.

Bob, I am in agreement with your advice and was heading in that direction myself.  But first, I thought we should be sure where he was starting from.
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Offline Tim Stagg

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Re: Electric Arf Nobler
« Reply #4 on: September 22, 2010, 08:58:55 AM »
Guys,

I will start the diagnostics, I hate to admit it but I am not sure of either. I used the firewall as delivered for engine thrust, it passed the eyeball check but I did not do any incidence measuring. The same applies for the wing and stab incidence.

I have applied a little bias in the elevator, it is natural and flush on the bottom of the surface, but I will look at the measurements to see where I am and report back.

Thanks for the input.
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Offline Bob Reeves

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Re: Electric Arf Nobler
« Reply #5 on: September 22, 2010, 11:03:26 AM »
Quote from: Tim Stagg on September 22, 2010, 08:58:55 AM
Guys,

I will start the diagnostics, I hate to admit it but I am not sure of either. I used the firewall as delivered for engine thrust, it passed the eyeball check but I did not do any incidence measuring. The same applies for the wing and stab incidence.

I have applied a little bias in the elevator, it is natural and flush on the bottom of the surface, but I will look at the measurements to see where I am and report back.

Thanks for the input.

I've been involved with the building of 4 ARF Noblers and you can bet your bippie if you just put it together using the stock saddles for the wing and stab odds are pretty good it ain't right. Time to get out the measuring sticks and your Xacto knife.....
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Offline Tim Stagg

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Re: Electric Arf Nobler
« Reply #6 on: September 22, 2010, 07:57:46 PM »
Nothin is easy

I should have known better. I am on the road for the next several days so I will not be able to investigate till the weekend.

Thanks Bob
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Tim Stagg

Offline Mark Scarborough

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Re: Electric Arf Nobler
« Reply #7 on: September 24, 2010, 06:09:30 PM »
just as a side note, I had the same problem with mine, what it ended up being was the bellcrank bolt would get some bind in it whenever a load was put on it, without a load it was really smooth and nice,, just another thing to look at is resistance in controls,,
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Offline Tim Stagg

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Re: Electric Arf Nobler
« Reply #8 on: September 27, 2010, 09:19:17 AM »
Guys,

Found the culprit. The incidence was off someplace. Decided to cut the stab and fix there. The stab had about 1/16-3/32 of negative in it. The motor had about 1/2 degree of positive in it. No wonder the plane could not decide where it wanted to fly.

I also removed the ball link I put in the  back and replaced with a free moving yoke system the I designed from a heavy duty clevis and a bolt. Have not tried it again as of yet but there has to be a huge improvement.

Thanks all for your suggestions, last time I trust an ARF to be aligned correctly.

Tim

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Tim Stagg

Online Brett Buck

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Re: Electric Arf Nobler
« Reply #9 on: September 27, 2010, 04:25:03 PM »
Quote from: Tim Stagg on September 27, 2010, 09:19:17 AM
Guys,

Found the culprit. The incidence was off someplace. Decided to cut the stab and fix there. The stab had about 1/16-3/32 of negative in it. The motor had about 1/2 degree of positive in it. No wonder the plane could not decide where it wanted to fly.

I also removed the ball link I put in the  back and replaced with a free moving yoke system the I designed from a heavy duty clevis and a bolt. Have not tried it again as of yet but there has to be a huge improvement.

Thanks all for your suggestions, last time I trust an ARF to be aligned correctly.


   That's a common issue with ARF Noblers - about half of the individual samples I see are off by about that much.

    Brett
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Offline Tim Stagg

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Re: Electric Arf Nobler
« Reply #10 on: October 11, 2010, 08:42:45 AM »
Guys,

Just an update, problem finally solved. After test flying with the new corrected incidences it still had issues with being soft around neutral and then having jumpy control inputs, took us a while to figure it out, but it was the adjustable lead out slider that I installed.  When you moved the controls while not under tension of flying, they moved just as free as could be.....but when you moved them while putting tension on them, they moved very stiff, almost binding. After cutting it open to look inside, turns out the front lead out was rubbing part of the structure I built around the lead out slider. This was causing it to bind enough under pressure where when I gave the input control i had no movement, so I had to provide more input with no movement and then all of a sudden, the model would jump either up or down.

I have been chasing my own control inputs. Now I am sure that the incidence was a problem as well, but I am thinking that this was the major culprit.

It flies great now.
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Tim Stagg

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