Monty Roberts wrote:
What I was hoping was that you had the name of somebody who had personal
experience with the older Garrett product line. There is no way your
buddy
working in the company can tell me anything. I'm sure he has signed
non-disclosure agreements. So have all the dealers. A retired
technician
that has experience rebuilding the whole product range is who I am
after.
Monty
You got that right Monty. I finally got up to a guy by the name of
Steve Arnold more or less second in command in the turbo charger
engineering
department. "We don't send out those maps!" I revealed all and he said
no way would a turbocharger turbine work for road load HP on a gas engine.
He said you must design it from scratch. He recommended a company called
Concepts ETI in New Hampshire. Ever hear of them?
He had a hard time imagining what it was I was talking about even after
I told him
we were looking for a point design turbo compound. Kept saying turbo
compound
won't work at road load. This after I told him we were not designing a
conventional turbo compound engine. All we needed was a 40 HP point
design. We
intended to bypass the exhaust gas at high power to prevent over speed.
There are creative engineers with imagination and then there are engineer
suits. :)
Maybe I need one of those model turbojet engines and throw away the
compressor :)
Wouldn't that be a hoot if that worked?
The subject of aircraft engines never came up because I did not want
to be shut off immediately.
I am discussing things with a Garrett ex employee. If that proves fruitful
I will upload his name and phone number.
Paul Lamar
Yes I have heard of ETI. I have most of their text books. Mostly they are
survey books of the available literature, and just enough info to convince
you to buy some of their multi thousand dollar software or attend one of
their multi thousand dollar courses.. Not a lot of help, but somewhat
useful. I'm not surprised at your experience with the "engineer" at Garrett.
I think you could make one of the larger turbocharger turbines work. You
will probably have to trim the wheel to match your situation, and try to get
one with blading that is "close" to what you need. Then use a nozzle guide
vane rather than a scroll to get the thing to work where you want it to.
Lots of testing, testing, testing. And how do you find a turbo with the
right wheel, then get a part number? Actually it is much easier to design
and predict the performance of axial turbines. However, they cannot make as
much power with a single stage as a properly designed radial inflow design.
None of the axial designs out there for the hobby turbines is large enough
for what you want. Axial impulse turbine is the best bet I think for this
application.
Road Load-translation the engine is loping along hardly working and there is
no energy in the exhaust to use. Airplane is different especially at
altitude and high power settings. You are not going to make it work at 50%
power. You will have to use a VP prop full throttle. Use the prop to set the
operating point.
Don't waste your time on the Latham. Radial is much better for big delta P
for low weight and complexity. Frontal area is not a concern here.
Monty
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