Matt,

I have a friend who's not very jet knowledgable who's got a P-70. He's complaining that the engine has no throttle response between idle and approximately half throttle, then at about half throttle it suddenly jumps to about mid thrust. I haven't had a chance to look at the engine or radio set-up yet, but thought I'd ask before I go over and see if I can help him, thought I'd ask a few questions?

Is there any known issues with slow throttle response in P-70's?
Think this is an engine set-up problem or a radio set-up problem?
Ever heard of anyone else that's had this kind of problem or had to use a throttle curve to get linear response?

Thanks,

Jerry Neuberger

if the throttle is set linearly that's pretty much how it should respond, you don't start building significant thrust till over 1/2 stick.

A spool-up time of 6-7 seconds from idle to full throttle is also normal.
I am starting to play with a throttle curve to get a more linear throttle response.

Hi Jerry -

Anyone here in SD that I might know?

The P-70 still has "old school" throttle response - like the old P120 in my Boomerang, about 5-7 second slam time on a good day. Your description sounds normal, you just have to get used to it, especially on approach.

I have a throttle curve set up in my 10X that works fairly well, I can show you how to set it up, or send you the pertinent specs if you know how to program a curve in your buddy's TX. PM me here or the club newsletter has my home phone listed.

Cheers -

Barry

Hi Barry,

It's the P-70 Don G. has in his Bobcat. Don't recall for sure, but think he got the engine from Frank. It is one of the old school P-70's and I've flown it a couple times and thought the throttle response was pretty normal, but he keeps complaining about it. Think I'll go over one of these days and plug the GSU in during a run and watch the RPM to see what it's actually doing and if normal, I'll just program a positive curve in the throttle channel to make him happy.

Thanks all!

Hi Jerry,

A reverse expo curve can help, it provides more linear response through the mid range. I have a chart of what it looks like somewhere on this site, I will search for it later.

Sorry for the late reply, beyond busy at real work.

Not a problem, Matt, especially since part of what's been keeping you busy was doing the SE conversion and bearings on my P-60 :&gt

Jerry

Matt isn't a hands on repair guy at JetCat, he's been optimized at non paid support where he is priceless