Quote:
Originally posted by beepbeep
Hmm...I don't know where to start.
Aircraft engines have whole different set of specifications and reliability is a paramount. That's one of reasons we still see WWII technology in small aircraft engines. It's tried and true and few dare to change it.
Have you checked that such alteration of your engine is legal to begin with? I mean, you cannot just "park it on a hard shoulder" should that supercharger belt snap...
Regards.
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Thanks for checking in Goran, it's been a while since we "chewed the fat".
Actually, the limits on general aviation have more to do with the fear of liability from the lawyers than any real "reliability" issues. Unfortunately as long as we have a litigation happy society over here, we won't see real change in commercial (piper/cessna/etc) aviation for quite some time. It doesn't however mean that it can't or shouldn't be done.
Fortunately, the FAA has an experimental classification which is very broad and allows for some very creative adaptations. This being a "homebuilt" and already certified under the experimental rules gives me a huge amount of latitude.
That being said, I spent quite a few years "picking up" wrecked airplanes to really understand and appreciate the concept of safety. (Being the Safety Chair and part of our NTSB "Go-Team" at the airline I fly for helps a little too) So, this will not be a duct tape and baleing wire effort by any stretch.
Now, for my needs.
This will not be a "cruise only" airplane. I am building this to +8/-6gs and intend to use it as such. I spend my workday cruising straight and level, so I want my off time to be spent vertical and inverted. I need a responsive engine that handles negative as well as positive g loads and will not complain with a lot of rapid throttle movements.
I don't really need boost at idle, but I can't have a lot of lag either. What is the normal rpm range of the current stock of turbos? I am only looking for a 2000 rpm window (1000-2800) and I am sure that virtually any turbo can offer that. But then again, I am full of "theory" and short on practical use.
I remember you were telling me before that these modern turbos are using engine coolant, so what do I use for an air-cooled motor to keep the bearings cool? Oil?
Are you guys running inter (or humor me here "after") coolers? Would you encourage or discourage the use in this application? I think I can plumb one and I might even be able to use the byproduct for cabin heat, but I don't know yet.
I know I am beating a dead horse with you here, so I apologize in advance BUT, I know a ton of guys using Paxton/Vortec etc and I haven't heard of one failure (other than belt related) but I won't harp too hard on this, this time because as I said before, I have no way to effectively drive the darn thing. I had however thought of what to do as a back up due to component failure and I was considering a pseudo-alternate air door if you will, downstream of the compressor so that if the compressor is lost, it would run purely naturally aspirated, but again these are very basic thoughts only.
Thanks for your input (and everyone else here) and for the link. I hadn't seen a 2 stage/2 speed supercharger since I flew a Convair 340 (R2800) years ago. I miss those old radials.
Pete