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Engine options for my Lazair

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Noeson

Member
Joined
Sep 27, 2020
Messages
23
Started my own thread on affordable engines for Part 103 ultralights because I am veering into weirdo rc airplane and electric territory:

I have a 142 lb Lazair with 2 x 5.5 HP engines and a 400 lb MTOW and I am not eager to fly it until I get more power. The only good reason for me to go with a gas engine is range, but with a 5 gallon max tank for ultralights that advantage is limited. I can see why a handier person would want to go with gasoline but for me and my limited skills it's a rabbit hole. For a LSA it's an intriguing solution though!

Saito engines run about $120 to $150 per HP and per lb, including mount and muffler.

https://www.horizonhobby.com/product/fg-90r3-90cc-3-cylinder-gasoline-radial-engine/SAIEG90R3.html
or the twin 100cc:

https://www.horizonhobby.com/produc...nder-fg-100ts-gasoline-engine/SAIEG100TS.html
An ultralight would need 2+ of these engines, but that's a feature and not a bug when flying experimental aircraft, no?

But for my plane: Roto Max 150s looks like my best option at the moment and that leaves 100+ lbs of useful load for a 22 lb chute and 8-10kwh of batteries. My Lazair is lighter than the model Dale Kramer electrified and I weigh 150 lbs give or take a cheeseburger, so I am maybe 100 lbs ahead of e-Lazair already. A 4kw cruise seems doable.

In the rc airplane world guys are getting a legit kw per 50 square feet of solar cells, Lazair wing area = 144 sq ft., plus tail assembly Why leave up to 3kw on the table? Solar should be part of the drivetrain solution. If I could get half of the 4kw I need to cruise from solar then my 10 kwh battery pack is going to give me some pretty good range!

Back in the day Dornier used 2, 3, 4, or even 12 engines because he was designing with unproven emerging technologies and scarce resources and I think that applies today with electric. An array of motors may be preferable in development to an all eggs in basket single motor.

The best off the shelf complete drivetrain I am aware of is Chip Irwin's for the Zigolo but it costs $17,500:

Zigolo – Aeromarine-LSA
  • Battery Packs: 2 x 3.1 kwh 14S/20P/15KG, 60Ah
  • Motor: 20kW continuous, 28 kW peak, low noise, low RPM
I am just spitballing here, comments are welcome.
 
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