HI Mike

The answer  is NO  they are  differant cases  but the standard PA 40 .51,61,65  all have  the exact same footprint and  bolt pattern, so they will interchange with each other.
The Merlin series 40 ulltralight, is a smaller case and  pattern ( same as a ST 35-46)
The new Merlin 75 85  is a larger case and has a  ST 60 bolt pattern

Regards
Randy

>>The answer  is NO  they are  differant cases  but the standard PA 40 .51,61,65  all have  the exact same footprint and  bolt pattern, so they will interchange with each other.<<

Does this mean I can switch out my outstanding PA 40 in the Cobra for a PA 65?   

Randy 

NOPE , you have the Merlin series ultralite 40 it has a differant bolt pattern

The original 40 51 61 65  will all interchange

The Merlin series 40 UL  has the  same  bolt pattern as  a  Super Tiger 40-46

The  other Original motors  40 51 61 65  have the same bolt pattern as the  OS VF  or  SF  series

The  New Merlin series  75  85   have  the  same  bolt pattern as  a  ST 60

REgards
Randy

Mr. Randy Smith,
(Too many "Randys here! hahahaha)

Curiousity here!!!  Can you shed some light as to why the last time I saw the Katana, you had switched back to the 51?  (at least I *think* you had)
I know Aaron got the 61 you used at the NATS Top 5 and it's SWEET!!!

Just curious as to what feature/characteristic you like in regards to the Katana and the 51.
Thanks!
Bill <><

Hi Bill

In my mind it is very important to "match"  the  airframe  and  engine.
My Katana is only 50 ounces with the 51 setup. The 51 is a very powerful engine so I can have the nice 4-2 cycle and have the motor come on and off of a  4-2  very quickly.
I perfer this type of run in this airplane. When I have the  61 or 65 in it  they run in a big strong 4 cycle and do not have to have any break. Not a bad  run , Its  just I like the 51 run better.
By the way both trips to the NATs top 5 had the 51 in the plane. One had 25 to 30 know winds, the plane and 51 handled them  pretty well.

Regards
Randy

Hi Bill

In my mind it is very important to "match"  the  airframe  and  engine.
My Katana is only 50 ounces with the 51 setup. The 51 is a very powerful engine so I can have the nice 4-2 cycle and have the motor come on and off of a  4-2  very quickly.
I perfer this type of run in this airplane. When I have the  61 or 65 in it  they run in a big strong 4 cycle and do not have to have any break. Not a bad  run , Its  just I like the 51 run better.
By the way both trips to the NATs top 5 had the 51 in the plane. One had 25 to 30 know winds, the plane and 51 handled them  pretty well.

Regards
Randy

Hi Randy,

Thanks for the insight.  Since I have seen the Katana in your hands with the 51, I can attest to the run. 

The 51 is a very strong engine!  When we put mine in Aaron's Geo XL, the plane didn't miss a beat.

Makes me wonder about the previos question I asked concerning a 51 in the USA-1!  I had talked to Billy about that.  I do think it will be PLENTY of power!  With a ST G51, mine was a real good airplane.  And I really do know how much more power the PA 51 makes.

Another question:  Billy advised me to use the shaft exstension on my USA-1 to move the engine back, like he did with the 46.  What are your thoughts about doing that with the PA 51?

Thanks!
Bill <><

Hi Bill

The  PA 51 is a pretty long engine, and  if it was mine  I wouldn't use a shaft extension
th engine is  AAC so it isn't a heavy motor  at  all

Regards
Randy

Thanks, Randy. 

I haven't "looked" on the plans yet and seen how my PA 51 fit to them.  I would definitely rather not use the extension. 

At my present level, I think a USA-1/PA 51 would be the ticket for our local contests as a "double duty" plane!

Bill <><