Microlighters

I'm thinking of installing a Rotax 503 with a 2:1 (B box) into my KR1. The aircraft is designed for a direct drive VW 1834 engine turning a 52/41 prop and generally cruises at about 120mph. I intend running a 52/54 prop on the 503. Can the experts on this forum give me some guidance, will the 503 drive a 52/54 prop through a 2:1 ratio box? What should I be looking out for.... or is this just a crazy idea.

Call Peter De Necker, he will be able to tell you immediately

(011) 805 1491

You will need a 582, 2.62:1 c-box at least, and a 3 blade adjustable prop, not longer than 60", lest ground clearance will become an issue. This will be very interesting. Keep us informed please. :D

Are we starting to look into some Pylon racing here
Gonna haveto get my Next aerie going quickly

Thanks for the info guys... I had a chat to Pieter this morning, He's not sure if the prop/engine combo will work so needs to do some number crunching and will get back to me.

Here's a little more info on the project:
My KR1 has a standard retract system so prop length is limited to 52" hence the 2:1 gear ration I'm using. I'll be importing a special 2:1 gear set from Rotax, the gears have a helical cut to eliminate harmonics. If the 503 can turn a 52/54 at 3200rpm (6400 engine rpm) I should get about 160mph. (The standard 2.58:1 ration will require a min 58/61 pitch prop which is too long for my application). The problem I have with VW's (I have a KR2 and VP1 with VW engines) they are heavy when you add starter motors and an electrical system. The Rotax is nice and light, has an electrical system built in and you can add a starter without adding too much weight. The KR1 has a 5meter wingspan so I need to keep it as light as possible.