Mailing List flyrotary@lancaironline.net Message #41489
From: Greg Ward <gregw@onestopdesign.biz>
Subject: Re: [FlyRotary] Re: Fuel burn
Date: Mon, 11 Feb 2008 08:51:31 -0800
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Tracy Says the drive will handle 400 HP at take-off, and I won't be using the stock turbos.  I'm being told that the TO4 that John Slade is using is under-sized for the 20B, so I am researching what the next step up is.  There is also a guy in LA that builds manifolds that are supposedly immaculate, and inexpensive, we'll see.  I think limiting it to 6000 rpm makes total sense.  Anyhow, heading to the shop for a grinding session, have a great day!!
Greg
----- Original Message -----
Sent: Monday, February 11, 2008 8:43 AM
Subject: [FlyRotary] Re: Fuel burn

Ernest, The 20B will easily hold up to 400 HP. The real question is will the Redrive? The only source for a drive that is designed to handle that type of power is the Mistral planetary. They are turboing the 20B engine to 360 HP for certification. If Greg uses 400 for short periods he should be fine, If he has an adaquate drive.
Bill Jepson


-----Original Message-----
From: Ernest Christley <echristley@nc.rr.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Mon, 11 Feb 2008 6:08 am
Subject: [FlyRotary] Re: Fuel burn

Greg Ward wrote: 

> O.K., time to throw a little F matter into the fan. I am sitting in my new shop, with a Lancair Legacy RG, and a relatively new 20B "D" series on a palette. I got the engine complete with everything it had in the Cosmo that it came out of. There isn't even a coat of grease on this thing. Radiator, oil cooler, air conditioner, condenser, ECU, injectors, coils, motor mounts, and about 100 pounds of extra stuff came with it. My buddy (he has been selling engines for 15 years) in LA that sold me this engine ($4500.00) is in constant contact with people who race this motor, and I am getting a lot of input on how to set this thing up. I have ordered Tracy's gear drive, and plan on generating 400 HP on take -off, and about 75-80% at cruise. My max rpm will be 8000. You have no idea how much input I am getting from the racing set. They are saying that with a variable boost (electronic) controller, I can vary the boost at any given altitude, as much or as little as I want, and tweak this thing for max performance. They can't believe that I am asking so little from this engine. 

> This will get us started; 
> Greg 
> Greg, I don't want to rain on your parade, but there are three questions you have to ask yourself: 
 
- Can I reliably pull that many horses out of the motor for hours on end? 
- Can I carry enough fuel to support pulling that many horses for hours on end? 
- Can I keep the engine from melting while pull that many horses out of it? 
 
It's been demonstrated on this list several times that not everything from racing translates directly to airplanes. For instance, 400Hp will require twice the radiator volume that most of us are using, along with the larger associated ducting and cooling drag. Will the reduction in reliability and increased fuel burn be paid for by the extra speed once the effects of the extra weight and cooling drag are factored in? ie, you will go faster, just not as much as "double the Hp" would imply, because of the cooling drag. I don't think most racers have to worry about that to much, but you could wind-up with a system that just cost you more to go to only relatively close places faster. 
 
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