EAAAirVenture OshkoshShopJoin

Light Sport (and Ultralight) Engine Requirements

Posted By:
Douglas Hank
#1 Posted: 9/2/2009 17:52:57

This is my first post, and it's mostly a hypothetical issue, so go easy on me:

As the regulations for Light Sport and Ultralights planes read, the plane has to have a "single reciprocating engine". 

Does that also include an unspoken understanding that the engine may only drive a single propeller?  (In some situations, possibly for prop clearance reasons, two smaller props would work better than a single larger one.)

Conversely, how the FAA would view joining two (originally) separate engines together to drive a single prop?  What I'm thinking here is that if of one quit in flight then you'd still have at least some power to work with - but without the added difficulty of off-center thrust (which I'm guessing is the purpose of the 1-engine requirement in the first place). 

The added complexity might make it more trouble than it was worth.  -But hey, I figure the first part of creating an experimental aircraft is figuring out if it's technically and legally possible in the first place!



Dave Prizio
Young Eagles Pilot or VolunteerHomebuilder or Craftsman
#2 Posted: 9/3/2009 13:39:10

I think the thing to keep in mind with light sport is that powerplant weight is critical.  For instance Continental is spending  lots of money to squeeze 25 pounds out of their O-200 engine, so it will have a chance of competing against the lighter Rotax and Jabiru engines of similar horsepower.  With a maximum gross weight fixed at 1,320 pounds on wheels the battle is to get the best possible useful load out of that limited weight.  The manufacturers who can maximize useful load will have a definite advantage in the highly competitive LSA market. 

The things you are thinking about have merit to a point, but they will add weight (not to mention complexity).  Thus they are unlikely to receive much serious consideration.  However, keep that brain churning.  Creativity is what keeps us moving forward. Where would Burt Rutan be today if he hadn't done things other people thought were crazy?