ASP 180 Four Stroke

  • Phil Ford
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10 years 8 months ago - 10 years 8 months ago #1786 by Phil Ford
ASP 180 Four Stroke was created by Phil Ford
I have a ASP 180 4str, swinging a 17x8 prop, installed in my Super Chipmunk. It runs happily and has quite a few flights BUT! it arrives at max RPM (8300) at half throttle which is rather annoying because after half stick there no nothing. :( The throttle barrel moves fully from idle to fully open so it is not that.

I had a quick discussion up the field with a few members on this issue I would like to resolve. After checking throttle movement it was suggested changing fuel from 5% Nitro 4stroke mix which includes some castor to Content 10 (10% nitro) I have got Optifuel 12% nitro/synthetic oil which is near enough. Albeit, power is not the problem, it pulls like an ox but the throttle.

Any ideas Guys?
Last edit: 10 years 8 months ago by Phil Ford.

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10 years 8 months ago #1794 by JonTappin
Replied by JonTappin on topic ASP 180 Four Stroke
Sounds like the carb fitted is just not giving a linear response, I wouldn't think there is much you can do to change that.

If it were me I would just set up a throttle curve to produce a linear response. In your case the curve would be very shallow for the first 3/4 of stick movement from idle and up, then the last 1/4 stick movement to full power would be steep. This would produce movement of the barrell from idle to half open over the first 3/4 ish of the stick movement. As long as you end up with a linear response, it really doesn't matter where the barrell is at each stick position.

Hope that makes sense.

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10 years 8 months ago #1799 by Phil Ford
Replied by Phil Ford on topic ASP 180 Four Stroke
Thanks Jon, I will set it up as per your suggestion so it feels linear on the stick.

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10 years 7 months ago #1811 by
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Hi Phil, Sound like you are reaching max revs and you cant scale the amount of air that you can get through a set size hole in a given time, need to increase load then larger throttle opening will work, increase the nitro will increase the oxygen content of the induced mixture, as air only as 14% oxygen anything that increases that will help, but I would put on a coarser prop and give it a try you can then throttle down for the same speed ,regards Frank

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10 years 7 months ago - 10 years 7 months ago #1813 by MikeSeale
Replied by MikeSeale on topic ASP 180 Four Stroke

FrankRobinson wrote: air only as 14% oxygen


Just in case any of our junior members are reading this...air only has 21% oxygen. Make sure you remember this for both your English exam as well as science.
Last edit: 10 years 7 months ago by MikeSeale.
The following user(s) said Thank You: DaveBright

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10 years 7 months ago #1814 by
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9 out of 10 again

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