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Author Topic: Piped engine question...warming it up...  (Read 1533 times)

Offline Steve Helmick

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Piped engine question...warming it up...
« on: May 19, 2011, 03:15:07 PM »
Like I have posted before, I think a lot of folks have bad runs because they set the NV before the engine is up to temp. Often, this is clearly shown by the engine's rpm increasing as the flier heads for the handle. Don't do that!

With my muffler planes, I  temporarily & intermitantly block off the uniflow vent or pinch the muffler pressure hose. The idea is to get the engine leaned out to the peak, to get it heated up faster. When it comes back down to the same rpm twice, it's hot. Once hot, I set the NV with the tach, and I'm ready to launch. It works very well, IMO.

My question is: Can I do this on a piped engine? Will it come back down to its normal launch rpm, or will it stay peaked?

In this case, the uniflow is open to ram air. I have blocked the vent for short periods, but not long enough to get it really lean, just lean-er.  :-\ Steve
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Offline RandySmith

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Re: Piped engine question...warming it up...
« Reply #1 on: May 19, 2011, 03:53:29 PM »
Quote from: Steve Helmick on May 19, 2011, 03:15:07 PM
Like I have posted before, I think a lot of folks have bad runs because they set the NV before the engine is up to temp. Often, this is clearly shown by the engine's rpm increasing as the flier heads for the handle. Don't do that!

With my muffler planes, I  temporarily & intermitantly block off the uniflow vent or pinch the muffler pressure hose. The idea is to get the engine leaned out to the peak, to get it heated up faster. When it comes back down to the same rpm twice, it's hot. Once hot, I set the NV with the tach, and I'm ready to launch. It works very well, IMO.

My question is: Can I do this on a piped engine? Will it come back down to its normal launch rpm, or will it stay peaked?

In this case, the uniflow is open to ram air. I have blocked the vent for short periods, but not long enough to get it really lean, just lean-er.  :-\ Steve

Hi Steve

We do this as a routine, just put your finger over the vent and let the motor rev for a couple of seconds, when you move your finger it will drop right back, then set the needle, it is most important for first flight in the day

Randy
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Offline Brett Buck

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Re: Piped engine question...warming it up...
« Reply #2 on: May 19, 2011, 05:10:50 PM »
Quote from: Steve Helmick on May 19, 2011, 03:15:07 PM
With my muffler planes, I  temporarily & intermitantly block off the uniflow vent or pinch the muffler pressure hose. The idea is to get the engine leaned out to the peak, to get it heated up faster. When it comes back down to the same rpm twice, it's hot. Once hot, I set the NV with the tach, and I'm ready to launch. It works very well, IMO.

My question is: Can I do this on a piped engine? Will it come back down to its normal launch rpm, or will it stay peaked?

  Of course. If it doesn't come back your pipe length it probably too short. Of course the effect you are trying to get is that the setting changes as a result of warming up.

   Brett
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Offline Steve Helmick

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Re: Piped engine question...warming it up...
« Reply #3 on: May 19, 2011, 06:23:59 PM »
Thanks Randy and Brett. I'm so glad you two agreed on this! Conflicting info makes me, uh...conflicted.
 ~>  Steve

PS: This retirement gig is great. Like being on welfare without the stigma, drugs and munchies. 
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"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Brett Buck

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Re: Piped engine question...warming it up...
« Reply #4 on: May 19, 2011, 06:32:22 PM »
Quote from: RandySmith on May 19, 2011, 03:53:29 PM
Hi Steve

We do this as a routine, just put your finger over the vent and let the motor rev for a couple of seconds, when you move your finger it will drop right back, then set the needle, it is most important for first flight in the day

Randy


  It also takes a surprisingly long time to get rid of the after-run oil. Sometimes I can start my engine, set it, get out to the handle, and go a couple of laps, and still be able to smell a bit of it in the exhaust. Warming it up accelerates process.

   Brett
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