mstull
R.I.P.
I need to compliment Doug Hart on his accomplishment... making truly legal, safe, fun U/Ls at an amazingly low price. This is so important for the future of Part 103 operations. I might even buy one eventually. I can't even buy the materials for one of my designs for what he sells a completed airframe. If you haven't heard, Doug just quit his job to make U/Ls full time.
http://www.hartaero.com/
But potential customers should be realistic with their engine choice. Read AC103-7 #11. Anything over about 35 Hp will exceed the legal speed limit. And there's few good engine choices in the 30 Hp to 35 Hp range.
The Big Twin might pass the speed limit, if it doesn't put your plane over the weight limit.
http://www.culverprops.com/big-twin.php
An MZ201, run direct drive to limit its power and thrust, will work. It's one of the lightest choices that has enough power.
http://www.compactradialengines.com/mz201.html
Doug sells both these engines.
The MZ34, and similar large singles, might work. But their tremendous vibration is so destructive, I doubt you'll be satisfied in the long run. And they're a little low on power... especially for heavier pilots.
Another option would be to stick an oversized prop on a twin cylinder engine with reduction drive. The big prop would limit RPM and thus power and thrust. Its power to weight ratio might be less than ideal. But running well below the engine's limits should help reliability. There are lots of 2 stroke twins that could be used that way, including Rotax, Hirth, and MZ... if you can pass the weight limit. You might need to choose a lighter airframe, like Doug's Sweet Pea line to be able to use one of the heavier engine choices.
Many of us are spoiled by the fantastic climb rates of our previous "fat" U/Ls. If you limit power and thrust to pass the speed limit, expect a more gradual climb. Please be realistic in your expectations, and careful with your engine choice, if you really want to be legal.
http://www.hartaero.com/
But potential customers should be realistic with their engine choice. Read AC103-7 #11. Anything over about 35 Hp will exceed the legal speed limit. And there's few good engine choices in the 30 Hp to 35 Hp range.
The Big Twin might pass the speed limit, if it doesn't put your plane over the weight limit.
http://www.culverprops.com/big-twin.php
An MZ201, run direct drive to limit its power and thrust, will work. It's one of the lightest choices that has enough power.
http://www.compactradialengines.com/mz201.html
Doug sells both these engines.
The MZ34, and similar large singles, might work. But their tremendous vibration is so destructive, I doubt you'll be satisfied in the long run. And they're a little low on power... especially for heavier pilots.
Another option would be to stick an oversized prop on a twin cylinder engine with reduction drive. The big prop would limit RPM and thus power and thrust. Its power to weight ratio might be less than ideal. But running well below the engine's limits should help reliability. There are lots of 2 stroke twins that could be used that way, including Rotax, Hirth, and MZ... if you can pass the weight limit. You might need to choose a lighter airframe, like Doug's Sweet Pea line to be able to use one of the heavier engine choices.
Many of us are spoiled by the fantastic climb rates of our previous "fat" U/Ls. If you limit power and thrust to pass the speed limit, expect a more gradual climb. Please be realistic in your expectations, and careful with your engine choice, if you really want to be legal.
