Light Aircraft Association

With regard to VW conversions, are the US-style belt-drive PSRUs allowed in LAA-land? What is the policy on the use of Bosch distributors and electronic ignition on VWs?

regards
Mick

well many kr2 are using electronic ign a whole variety of stuff
go onto great plaines web site for more info

I understand but what's LAA policy on belt redrives, for example? I've only seen regular direct drives and standard magneto ignitions and the odd Leburg out there.

regards
MB

Mick Bevan wrote:what's LAA policy on belt redrives

Given the slow revving nature of the VW engine in car use would you want to run a VW hard enough in a 'plane to make a reduction drive a useful addition. I wonder if the extra performance would offset the extra weight involved.

If I wanted to consider a reduction drive then I'd consider turning the engine round from the 'normal' aircraft usage and putting the prop on the gearbox end of the engine rather than the pulley-wheel end. There are sites out there that advocate and assist with that, but more often with heavier type 3 and 4 engines rather than the type 1 + 2 (beetle and van) engine.

Why turn the engine round? You can channel more power through the flywheel end of the crankshaft (it's where the power is designed to be taken from) and there's more strength and opportunity at that end for the physical fitment of a reduction drive.

If you are planning this sort of aggro, then maybe a Scooby-Doo (Subaru) engine would be a better starting point for your project!

As regards ignition options, look at the Great Plains Aircraft website and talk to LAA engineering themselves.
Main reasons for ignoring Bosch distributors is they stick out of the top of the engine and ruin the line of your cowlings, are only a single source of ignition (you normally require two), and they require an electrical system. If you go this way you need to consider the electricity generation and storage problems too!

I have never seen a psru fitted to a VW conversion, they dont rev enough to warrant one. As to which end to fit the prop well there is in my opinion only one end and it isnt the flywheel end. Ignition, well do you start your car with a crank handle, No so why continue to use magnetos. The electronic ignitions systems on the market now are far more reliable than any magneto ever will be.

Here's a VW with a PSRU...

http://www.vw-engines.com/index.htm

and another...

http://www.valleyengineeringllc.com/valleyintro.php

I think the trick is to make the engines rev fast enough to make a PSRU worthwhile.