Proposed Engines

[Aaron Novak]

Brock,
I apreciate the enthusiam. Using a unit head, cylinder and crankcase is nothing new. However it does introduce some complexity and loss of flexibility in design, especially in the prototype stage. You are going to need some equipment, and the knowledge and experience of how to use it. A medium size lathe is a must. The precision needed to fabricate a built up crankshaft is well beyond a drill press. I also sense a lack of familiarity with 2 stroke design....this is going to hurt you, and is a place to start educating yourself before you make a single chip or pattern. Unfortunately what you will find is that there are very few companies left that engineer and build high duty cycle high output 2 stroke engines. In fact I can only think of 2 or 3 in this country, so finding experts on the subject isnt going to be easy. I encourage you to follow your dream here, just be prepared for the amout of work it is going to take.

[Dave Prizio]

McCullough (the chain saw people) made 2-stroke, 4-cylinder engines for target drones that later became very popular with the Benson Gyrocopter set. If you can find one of those engines it could be very helpful to you to understand how such an engine can be built. I am sure there are still running examples around, since they made thousands of them. There is much subtlety involved in the design of such an engine that may not be obvious to someone who has not spent a lot of time with such engines.

In any case, good luck with your project.

Dave Prizio

[Eric Witherspoon]

Just out of curiosity, I've run across these guys before:
http://www.desertaircraft.com/engine...hp?Page=DA-200

19hp ~$2800. But that's for the fancy 4-cylinder.
18hp ~$1800 - For the "big" two-cylinder.
16.5hp ~$1400 - might be cheaper (and quicker) to set up your airframe to go with two of these guys.

[Flyfalcons]

Keep in mind the DA engines are fantastic, I own numerous DAs on my RC planes, but they are all turning in the 6000-7000RPM range. Do they pull, oh yeah, but probably aren't as efficient as a geared engine swinging a bigger prop. The DA-150, 170, and 200 turn props 30-32" in diameter. They just announced a 250cc four stroke engine though....