hi Marc, mistral has tested the mazda turbo, but they weren't satisfied with it. Mistral is very safety minded. They have a lot of demand for turbo's, and will proceed to develop them at a later stage. I agree that that will help a lot, and for a Glasair, a turbo is a good idea.

Paul janssens

I've looked at a lot of turbo maps and have not found one that would work for a 3-rotor at both sea level and at 18,000 msl.

Mark S.
Lancair ES, N/A 20b

Could you explain that a little more? How is the 3 rotor different in that regard than any aircraft engine?

Paul Lamar

The real question is why boost this engine at SL at all (if we want reliability)? All I've ever wanted to do is 'turbonormalize' it, IOW maintain SL pressure, hence engine output, at 25,000 or so-a typical certified application on many light aircraft. We only need to boost it when we begin loosing pressure as we ascend. Turbo maps have me a bit flummoxed as well because they are made mostly for cars and trucks operating at SL or close to it. I am sure an aircraft turbo spec would be much better than any Mazda turbo....... matched it to the output of the 3 rotor. An intercooler would be necessary as well. The controls to close the wastegate as you ascent could get bit tricky.....aircraft that are turbonormalized and FI (deck pressure injector shrouds, pressurized magnetos, etc) have many oil fed parts, but the new diesels (all
turbo'd) and many never aircraft now have electronically controlled wastegates, PRVs, and deck compensators.
Marc




The last turbo aircraft that I worked on was a couple of months ago, and was a Seneca 2, with 6 cyl Cont TIO360s. The turbos were mounted behind the engines where the exhaust piping came together (about
2 feet behind the engine in the back of the cowling) and had manual waste gates, no pressurized mags, no intercooler, no extraneous parts.
Flying the plane is a workout, especially during takeoff where you have to closely monitor temps, pressures and everything else normal pilots have to monitor. It proved very easy to over pressurize the engines during takeoff, even with the waste gate "closed". If the MP went over 30", you had to pull the throttle back a bit to keep it under control.
The turbos were small Garretts, not much larger than the stock Mazda turbos. There was about 2 feet of piping between the closest cylinder and the turbos, more distance to the front cylinders from the turbo. The oil line came off the back of the engine, into the top of the turbo, and out the bottom just like one on a car and drained back into the oil pan.
Nothing special. I did notice that the oil filter was twice as tall as one on a non turbo engine.

Adding turbo normalization to a plane doesn't have to be that complicated. A manual waste gate that is left open for takeoff and gradually closed to maintain 30" MP as we climb or in cruise would be sufficient. I would argue that an inter cooler isnt mandatory, if you only plan to use the turbo at high altitudes where the air is considerably cooler than at SL. I have seen more than one turbocharged certified plane without inter coolers.

Can we expect an altitude of 25k feet? Not realistically IMHO. I think a ceiling of 18k would be more than plenty. Just like in an automobile application, turbos are matched based on what you want performance to be. If you want a killer stop light to stop light response with little turbo lag, a low AR and small diameter impeller will get you there, but it will choke out at high RPM/pressures. For a diesel or continuous duty application, an AR closer to 1 would be better. A larger diameter turbine/impeller, larger gas chambers for better flow, and of course turbo lag. Match the flow of the turbo with the flow of the engine at the intended RPM and work load range.  I went with a modified Garrett T04, optimized for the flow of a 5 liter diesel at 3000 RPM. In this application, it produced 16 psi continuous. I plan to mount it like the Seneca, behind the engine with around 2 feet of exhaust pipe between the engine and the turbo. I will install a cooling cuff around the pipe at the extension piece that dumps overboard to cool the pipe before it gets to the turbo. This addresses these problems-

1. Hot exhaust- the exhaust is cooled for a bit between the engine and the turbo-
2. Noise- I still get my turbo, which is known to quieten the engine.
3. Turbo-charging- I will set it at around 8psi to start with with a mechanical spring loaded waste gate actuator. I am expecting that 8psi spring pressure will remain fairly constant since it doesn't rely on differential air pressure to work.

My NA viking had a ceiling of 15k, and with 300 hp would get there no problem. There are vikings with turbo IO540s and now 550s that are normalized with ceilings of 17k. My Viking cruised at 160 knots at 12.5 gph at 12500 ft, the turbo version gets 180 knots at 15000 on 15 gph. A little faster, but lots more fuel burn. Again, manual waste gates for the vikings. Procedure is to set the wastegate to open for takeoff at SL, and if you are at higher elevations do not exceed 30" MP. Again, one more thing to monitor during a busy time.

With an EFI, automatic operation could be achieved, just read the outside pressure, and the MP, and make sure that the MP stayed within limits. And temps, and RPM, etc.
I am working on this to be implemented in the EFI system.


Kevin Alderman

Kevin,
Glad you are working it out. I have worked on various TC aircraft, right now a C337G-T with boosted 210/225 hp Continental engines. Lots and lots of plumbing. Given, manual wastegates and no intercoolers is workable (re the Rayjay twin Commanches?) but the engines did not live long. Too prone to overboosting and ham fisted pilots that caused lots of issues, and then there was bootstrapping and other troubles. Same with the Skylanes that were turbo-a manual cam closed the wastegate as the throttle was pushed in..........never did like it. Anyway, good luck. PS: this is a good site, lots of info. I refer to them often, but they do not suffer fools. Same people as Gami.
http://www.taturbo.com/frames.html <http://www.taturbo.com/frames.html> <http://www.taturbo.com/frames.html <http://www.taturbo.com/frames.html>>

Marc


 Might this be time to install a turbocharger to see if that could lower
the sound (and provide other benefits, once the cooling is sorted out)?
Marc


I have a lot of experience with equipment of all types- cars, trucks, BIG trucks, boats, planes, and heavy construction equipment. The common denominator with almost all of the turbos excluding cars is they do not have wastegates. My trackhoes, dozers, cranes, boats and even gasoline powered turbo charged electrical generators, no wastegates. The turbos are matched for the known operating range of the engines. The turbos are designed for continuous 100% duty cycle use for hours and hours on end. I think this is the key to solving this problem with the turbos on the rotary engines. Our first enemy is the unusually hot exhaust- so we move the turbo downstream and cool the exhaust- second is the thinner air and the tendency for the turbos to overspeed and fly apart- so we need to use a slightly larger impeller with an A/R of close to 1. This in itself will limit the speed of the turbo. I am not concerned with turbo lag and "instant" power. I can sit at the end of the runway for 2 seconds and get the turbo up to speed if need be. What I do want is a reliable turbo that will give me 8 psi boost on the ground, and a differential boost of around 13 psi at 15000 ft. My previous boat had 5.9 cummins diesels in it rated at 350 hp, and she ran a continuous 28 psi boost at 2400 RPM. For over 3500 hours before I swapped them out. It will work- just have to find the right combination.

Those are the numbers I am working with :)

I will keep you guys posted as I get the system put together.

Kevin Alderman


   Well said.  The one main caveat is that you have to use what will fit in your installation.