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Ultra flash out of trim at full throttle.

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Ultra flash out of trim at full throttle.

Old 12-21-2013, 05:24 PM
  #26  
mitchilito
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I like the idea of keying the throttle/elev mix to gear up. I'm gonna put a little in my UF.

Just FYI, my CG is quite rearward and I get just a tiny amount of climb at full throttle. All other throttle settings stay in perfect trim.
Old 12-21-2013, 09:08 PM
  #27  
asimatt
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Originally Posted by txshan130
Well I have a rhino in it so a lot of difference between 22lbs of thrust and 36. I just flew it today and it wanted to slightly go up, but it seems everyone's pretty much does that. When I go half power and then idle, it stays level.
+1
Old 12-22-2013, 07:39 AM
  #28  
Alcool
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I flew my flash all last summer without any trouble and then all of a sudden I noticed the same problem.
For me it turned out to be the little centering tabs in the back of the exhaust tube kind of flatten out a small amount.
You really didn't noticed it on the ground but I pulled the tube and bent then a little more and presto the problem went away.

Hope this helps
Al Coolen
Old 12-22-2013, 09:43 AM
  #29  
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TH Futura is a shocker for this, climbs under power or into a headwind. Fitted an iGyro and all good!
Old 12-23-2013, 05:12 PM
  #30  
stevekott
 
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If your plane is climbing with increased airspeed and the incidence is set right it's probably just a little nose heavy ... regardless of the manual CG. For good reason manuals would prefer you error toward a nose heavy CG.

A stable plane is designed so that when it starts loosing airspeed the nose will drop a little and pick up airspeed. The down-force on the horizontal stabilized reduces with the decrease in airspeed and causes this to happen balancing at the CG.

If the CG is too far forward you are trimmed straight and level you are flying with excessive down-force in the horizontal stabilizer. As the airspeed increases this becomes greater and greater and causes the nose to climb. It is much better to have this, than too far aft CG.

Too far aft, the nose will drop with excessive speed but when you are flying slow the nose will start to climb, slowing the plane and causing the nose to climb even higher causing an imminent stall.

That is why it's better to be too nose heavy rather than too tail heavy.

So a healthy stable airplane will climb very slightly with increased speed, also very true with full sized aircraft. If it's climbing too much, move the CG aft a little. If it ever has a tendency to descend at higher speeds .. the CG is too far aft and will be unstable at low air speeds.
Old 12-23-2013, 07:47 PM
  #31  
husafreak
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That's an excellent way to describe what is happening. Particularly with the UF, it has a huge speed range. While straight and level at all speeds and thrust settings would be great, we do not enjoy flying planes that "tuck" or dive at speed or with power. Better to err on the stable/safe side.
Old 12-24-2013, 02:36 AM
  #32  
mitchilito
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Yes, thanks to SteveKott for a great explanation. I set all my aerobatic aircraft up on the verge of tail heavy to minimize unwanted deviations during aerobatics. As a result I have to live with aircraft that want to "float" in the landing pattern and require careful attention to keep them from slowing themselves down too much. Planes set up this way don't want to glide. But during a nice low slow roll the length of the field, close to the ground and hauling *ss, I would not have it any other way
Old 12-24-2013, 07:01 AM
  #33  
txshan130
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I guess I will try moving my CG a slight bit back and see if that helps...
Old 12-24-2013, 07:40 AM
  #34  
Lownverted
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Originally Posted by tobba
TH Futura is a shocker for this, climbs under power or into a headwind. Fitted an iGyro and all good!

Into a headwind? How is that any different? The plane sees the same indicated airspeed upwind or downwind, only the ground speed changes.
Old 12-25-2013, 09:14 PM
  #35  
highhorse
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Originally Posted by Lownverted
Into a headwind? How is that any different? The plane sees the same indicated airspeed upwind or downwind, only the ground speed changes.
Answer: You are correct in that it isn't different at all. The other gentleman is mistaken, but we are are all best served by not going there in this thread as the resulting furball would be the mother of all hijacks!
Old 12-26-2013, 01:15 AM
  #36  
davo580
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my boomer used to cimb at full throttle until i put a little down tim with a washer up front under the front engine mount bolts
Old 12-27-2013, 08:48 AM
  #37  
Lownverted
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Originally Posted by highhorse
Answer: You are correct in that it isn't different at all. The other gentleman is mistaken, but we are are all best served by not going there in this thread as the resulting furball would be the mother of all hijacks!
Lol of course you are correct about the ensuing furball. Still, I'm amazed that there are folks out there who think like that.

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