"Shock cooling"

[Learjetter]

Thanks Larry--I hope to make it to Dayton--even if only for a few hours one of the days.

Not to be argumentative, I get it that you need to reduce power to keep speed under control in the descent. But on engine start, let's say the motor's at 80 deg ambient temp, right after start it jumps to , say, 300+, right? That's tha same thermal stress you're describing, just in reverse, no?

[WebMaster]

Actually No.
If you watch the gauges, when you start an engine, you have max mixture, normally. That helps cool the engine. So, on start up, CHT and EGT are typically low. These temps gradually increase, which is why you want to warm up the engines, before take off. When you are at cruise, you have the mixture leaned out, and that makes the engine more efficient, and raises CHT and EGT.
Hal Stoen has some discussion on this. http://www.stoenworks.com/Aviation%20home%20page.html

http://www.stoenworks.com/Tutorials/...res%20and.html

[Learjetter]

Good stuff, Larry. Thanks!

[Red Air Rambo]

If you are getting a T or P model the speedbrakes really help getting down from alt without pulling the engines back too far...I think the rule of thumb is 2 inches of manifold pressure every 2 minutes.

Brent

[Learjetter]

Brent, thanks...the mission calls for Turbo so a T or P (or 310 HP Riley!) is what I'm looking for...some mountainous routes & airstrips...so speed brakes and gear door mods are also high on my list of wants...

[Red Air Rambo]

Originally Posted by Learjetter

Brent, thanks...the mission calls for Turbo so a T or P (or 310 HP Riley!) is what I'm looking for...some mountainous routes & airstrips...so speed brakes and gear door mods are also high on my list of wants...

Why the gear door mods?

[Learjetter]

Originally Posted by Red Air Rambo

Why the gear door mods?

I thought I read (somewhere on this site, or on the rtaerospace site) that the gear doors opening creates a significant drag penalty...so I think a mod that eliminates that adds an extra layer of safety (especially during an engine failure after takeoff). Also, if I recall correctly, getting rid of the doors simplifies the gear system a little (making it easier to maintain). Www.rtaerospace.com still advertises the STC for about $4G + labor...