Pietenpol-List: Re: Question on engine choice

[matronics]

Original Posted By: leonstefanhutks(at)webtv.net (Leon Stefan)
Subject: Pietenpol-List: Question on engine choice>Gang,> I have been reading with great interest all the e-mail concerning>the Air Camper for a few weeks now. One of the topics I'm really>interested in is the choice of engines. Now before I really get>started, I must tell you all that I have not ever built anything larger>than a 1/4 scale RC, nor have I ever converted an auto enigne for>Aircraft use. Right now, I'm just at the planning stages for my piet,>so please bear with me.> The other day I was thinking of what type of engine to use and I>began by making a list of what I thought the engine should be able to>do. The list went something like this:> - Weigh no more than a Model A. Approx 250lbs.> - Produce the required HP at an engine/propeller friendly RPM.>Somewhere between 2000 and 2800 rpm.> - Be a relativily new product> - Parts must be easily obtained.> - Inexpensive would be nice.> - Not require a PSRU> - Be very,very,very reliable!!!>Armed with these requirements I started searching the net and came>across what I believe is exactly what I need. Attached (I hope) is a>HP/Torque/RPM graph. I added some lines representing some target RPM's>and their associated HP ratings. If the attachment doesn't work,>here's what I found:> RPM HP> 2050 62.5> 2500 75> 2800 87.5>Obviously these figures look great! What is even better is that this>engine developes max torque, 155lbs ft at about 2500. The engine is>the 2.4L L4 LD9 by General Motors.> Armed with this info, I then turned to propellers. I first looked>at Eric Cluttons book and then at Ed Sturba's web site and took the>averages and came up with a 72 * 35 inch prop. The mathmatical>performance of this prop is:> RPM Approx Speed>These figures also look really good! At these rpms the engine should>be very reliable and last a very long time.> Now here's my question. What am I missing? Being as>inexperienced as I am, I'm of the belief that if it would work, someone>else would have already came up with it.> Food for thought anyway.>>>Bill>>________________________________________________________________________________

[matronics]

Original Posted By: John Weikel
In a message dated 9/12/99 10:26:32 PM Central Daylight Time, wihutson(at)yahoo.com writes:>Hey Bill,A Model A engine covers all the bases, and does it under 2000 rpm !!________________________________________________________________________________

[matronics]

Original Posted By: william hutson
Did I miss something or what? How much does this engine weigh? Looks likea candidate for a prsu to allow more rpms to push it up the power scalesome. Why do you not want a psru?...John W-----Original Message-----