Brian The aerovee lawnmower ignition has no method of advance at all. They use it as the backup ignition to the electronic unit which also has no advance but will produce a spark at low revs. I have a friend who recently had the electronic unit fail and in the process of finding the fault cranked the battery down to a point where it would no longet turn the motor over. Trying to prop start it on the mag system was futile as he just couldn't spin it fast enough to make it produce any spark. It aparently needs somewhere around 300rpm. We have just gone through this whole ignition thing on corvaircraft but I will risk it again. Take a look at the system that is installed on Serge's plane. It is a simple transistor controlled coil ignition triggered by an inductive pick up. It also sports a ready made centrifugal advance mechanism. This system has been used here by many builders and has been proven during more than 1500 hours of flight without a single failure on VW motors as well as a honda auto conversion. It does need a 12V supply though. Take a look at http://home.hiwaay.net/~langford/corvair/ignition/dene/ Regards Dene Collett KR2SRT builder South africa Whisper assembler See: www.whisperaircraft.com mailto: [email protected] ----- Original Message ----- From: "Brian Kraut" <[email protected]> To: "KRnet" <[email protected]> Sent: Thursday, November 23, 2006 02:32 Subject: RE: KR> "lawnmower" ignition
> Thinking about it a little more I do see one problem with a lawnmower type > of iginition. Lawnmowers and weed whackers have the ignition set pretty > much near top dead center. It makes them a lot easier to start and is also > one of the reasons why you have a fairly good sized engine to make the > little power that they do. The only way to get the power you should and > also make it start easy is with something like an impulse coupling. I > imagine that the Aerovee has some kind of way to advance the timing built > in, but once you have gone through all the trouble of making something that > works and is reliable you might as well just have gone with a regular > aircraft magneto. > > I guess that something like an electronic ignition with spark advance for > normal use and for starting with a quick and dirty lawnmower type set with > fixed timing for a backup is food for thought. > > Brian Kraut > Engineering Alternatives, Inc. > www.engalt.com >
