"Shin Gou" wrote in message
om...
Looking at RV-9A's specification (weight, engine, etc.), I think a
Rotax 914 can power it very well, may give a better performance than
O-235. However, the problem is Rotax is far to light to be installed
on RV-9A.

So I just can't help thinking, well, why not a new design around
RV-9A's wing and Rotax 914. The design will be pretty much on
fuselage. The benefits of this designe of new fuselage+RV-9A
wing+Rotax 914 should be:

1) the basic empty weight should be 100-150 lbs lighter than RV-9A.
Rotax 914's wet installation weight is about 80 lbs lighter than
O-235. There should be more or less some structural weight saving from
the lighter engine installation and lighter gross weight.

2)Rotax 914 has constant 100 hp output up to 12,000 feet so it gives
more horsepower at 8000 feet than O-235.

3)The fuselage, if built in composite, can be sleeker(not necessarily
much lighter though)

Overall, lighter weight+more horsepower at altitude+sleeker fuselage
should make this new fuselage+RV-9A wing+Rotax 914 design at least as
good as RV-9A with O-235.

Prove me wrong please.

Shin Gou

I've had similar thoughts along the lines of sticking a 914 in either an
RV-3 or an RV-9. Why not just extend the forward fuselage to get the w/b
correct? You'd also want to verify your stability margins because the longer
forward fuselage will tend to be destabilizing. Lengthening the fuselage
will cost you some weight in additional structure, but you should still end
up with a lighter airframe that uses less fuel.

On the other hand, why not build it with the 0-235 and go flying a year or
two sooner?

KB