New to GLOW flight. Non-linear throttle?
06-05-2002 | 07:54 PM
#1
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From: Sarasota, FL
New to GLOW flight. Non-linear throttle?
Is is typical for the last bit of throttle not to have much effect? 0-50%, seems like a lot of response, then it levels out linear to about 75%, and then 75% to full doesn't seem like much difference in speed, just louder.
Thanks,
-Rick
Thanks,
-Rick
06-05-2002 | 09:26 PM
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From: Lawton,
OK
New to GLOW flight. Non-linear throttle?
Yeah, for the average engine that's pretty normal in my experience. So-called half throttle, going by stick position, is usually about 70 or 80 percent full power. Some more expensive engines and carbs will have a more linear response. Others may have different experiences with their engines, but all of mine have behaved more or less as you describe.
06-06-2002 | 12:12 AM
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From: Columbia,
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New to GLOW flight. Non-linear throttle?
I agree with Crosswind. Sounds fairly typical.
A couple of things might be contributing to it though. When you say "doesn't seem like much difference in speed, just louder"... are you talking about in the air or on the ground? A high-drag plane will do this more than a low-drag plane. There is also some chance that you are over-propping the engine. What kind of plane, what engine, and what prop?
A couple of things might be contributing to it though. When you say "doesn't seem like much difference in speed, just louder"... are you talking about in the air or on the ground? A high-drag plane will do this more than a low-drag plane. There is also some chance that you are over-propping the engine. What kind of plane, what engine, and what prop?
06-06-2002 | 01:57 AM
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From: Sarasota, FL
New to GLOW flight. Non-linear throttle?
It's my own design. A sport/fun-fly. Low drag 40% laminar NACA low drag airfoil. OS 32 SX, 10x4apc @ 16.8K static.
06-06-2002 | 03:27 AM
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From: Columbia,
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New to GLOW flight. Non-linear throttle?
Interesting. Not too much prop... but maybe not enough prop. I'm assuming you are running the standard muffler. From what I've heard... to spin really high rpm's, that engine prefers a tuned pipe. Otherwise, if you have not already, you might try a 10x5 or 10x6... just for grins.
06-13-2002 | 01:12 PM
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From: Holliston, MA
New to GLOW flight. Non-linear throttle?
Yeah, thats normal. One major factor is that drag is related to the square of airspeed, ie 2x the speed requires 4x the power and 4x the speed requires 16x the power. So if full throttle generates 2x the thrust of half throttle, the airspeed only increases by the square root of 2, or 1.414.
Add to this the fact that even running static on the ground most engines don't have a truly linear rpm curve related to the throttle position.
As has been pointed out, the best solution to this (if you have a computer radio) is to set up an exponential curve on your throttle channel.
-Jeremy
Add to this the fact that even running static on the ground most engines don't have a truly linear rpm curve related to the throttle position.
As has been pointed out, the best solution to this (if you have a computer radio) is to set up an exponential curve on your throttle channel.
-Jeremy
