Good one mate, I knew you couldn't let it go.  

 

Hi George,

 

Well that certainly IS the problem.  I was all set to bolt a Lycoming on the RV-3, but I realize that what I need is a project, not a plane.  Since there's no doubt a single will work for an RV-3, there's really no reason not to do it. 

 

While it may seem wishy washy to go back to the RD-1C,  the damper on the Autoflight drive didn't magically fix the resonance problem, and the RV-3 has changed the power requirements.  For previous aircraft, I was only planning to have about 80 HP, and that would fall within the 6000 rpm limit of the Autoflight drive.  Now that I can use as much power as I can make, I need more RPM.  

 

The offset thrust line of the Autoflight drive would have worked well for the previous aircraft I was considering, but not so well for the RV cowl.  The mount plate on Tracy's drive is also really handy for mounting coolers for the RV cowl inlets. 

 

The Autoflight drive is about 12 lbs lighter IIRC, but I have the opposite problem with weight now.  A single made from stock housings is way overweight compared to 912S, but compared to an O-200 or O-235, it's just fine.  Using stock housings will just limit you to aircraft that were designed for 100-125 HP LyConts. 

 

Finally, I really like the carbon fiber ground adjustable prop that Sensenich makes, and the RD-1C rotates the proper direction to use it. 

 

I should probably be more concerned with building the plane for now, but I can't help but think of engine stuff.  I've got a partial mount on order from the guys who make Van's mounts.  I don't know if I'll try to make a beam style mount, or use a sandwich plate similar to the old CCI mount.  Either way, I'll size it to fit either the single rotor, or a two rotor as a fall back plan.  

 

Enough babbling for now. 

 

Rusty (watching the salt magically melt snow)

 

Rusty,

I'm all for agreeing to disagree, as well you know, but I'm still looking at making the damper harder, rather than softer as in the 2 rotor.

 

A man of your means may wish to opt for the aluminium end housings, I believe Larry who owns an engineering company is looking at aluminium housing for the long term - make sure their det gun surface treated. He has done a very good job of rehashing PL's Bellhousing design and is cutting his second pattern on CNC - great workmanship, great ideas and great fellow to boot..

 

I don't know what HP you really need but if more than 100hp look at the Rx8 high compression rotor - I recently had mine cut to accommodate 3mm apex seals, which gives me piece of mind as they run over my 42mm P-Port.

George ( down under)