Well, I have not turbocharged a rotary, but I have heard that 300-500 HP is not unusual from one turbocharged - although I don't think I would feel comfortable with those power levels for an aircraft. While an N/A rotor does not like back pressure, when you have a turbo force feeding it you have a different story. I don't want to mislead you when I'm talking about lag and spool up you may be talking about a few 100 milliseconds - to a second or two of time. In drag racing, of course, a 10th of a milliseconds makes the difference in a win. A few 100 milliseconds would probably not affect your go-a-round chances {:>).

However, as I always say - if one choice makes you feel more comfortable than another then you need to pay attention to your comfort level. I know of a few choices I had made because I deemed one choice technically slightly better - but never felt as comfortable with it as I would have a slightly inferior choice.

Ultimately, of course, you're de fellow that has to fly behind it.

Ed
----- Original Message ----- From: "Greg Ward" <gregw@onestopdesign.biz>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, December 18, 2007 12:18 PM
Subject: [FlyRotary] Re: Supercharging

> Thanks Ed;
> The below is one of the reasons for looking at a SC in the first place. > Specifically on a missed approach and go-around, in a ticklish spot, the > responsiveness of the SC vs. the time it takes a TC to spool up, might be > an advantage. And, as I have been hearing, back pressure (from a turbo) > kills HP in a rotary. Maybe I'm picking the nit a little hard here??
> Greg
>
> <snip> There are certainly advantages to a supercharger in some > applications - and
>> to a turbo in others. The immediate boost response of a roots type >> blower is about the only reason they are the bedrock of the top end drag >> racers. Unlike a turbo which needs some time to spool up, the roots type >> superchargers produce boost much quicker. There are several types on >> impellers designed to increase the efficiency of the root types blowers, >> but I am not aware of any that approach the centrifugal impeller in >> efficiency.
>>
>>
>> While the turbo uses the "free" exhaust flow energy, you do get back >> pressure with the turbocharger that effects (decreases) engine power so >> that has to be considered also. But, overall, its my understanding that >> the turbo is a bit more efficient and also does not decrease crankshaft >> power (at least not as much) as a supercharger. However, there may be >> other reasons (like not having to have all that heated exhaust pipes >> routing around to and from a turbocharger) as well as cost for using one >> vs the other.
>>
>> Gee, its great to be back {:>)
>>
>> my 0.02
>>
>> Ed
>>
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>
>
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