Weight considerations with O-320

[Lowrider]

There is advantage to a lighter empty weight by using a smaller engine, say an 0-200 v 0-320 but introduce a short field and high density altitude and the smaller engine frequently can't cut it. An extra 60 hp can make the difference in making a nice take off and being in the trees at the end of the runway...just my thoughts on having an 0-320.

Can the 100 lb increase in gross weight be authorized at a lower G rating and restricted to no aerobatics?

[blueisthenewblack]

Hi all,

I'm pretty set on building a Panther, and although I'm far from buying an engine, I just wanted to check on the feasibility of using an O-320 for my 6'2", 220 lbs. frame.

Bob Wooley's Panther Sport with the O-320 came in at 828 lbs. empty weight:
http://flywithspa.com/panthercave/viewt ... =324#p1665

Working through the numbers (feel free to correct me if I'm wrong anywhere, I'm a first-time builder):

Empty Weight: 828 lbs.
Gross Weight: 1150 lbs.
Fuel Tank Capacity: 27 gallons

Fuel Weight (full): 27 gallons * 6 lbs./gallon = 162 lbs.
Max Load: 160 lbs.

Fuel Weight (half): 13.5 gallons * 6 lbs./gallon = 81 lbs.
Max Load: 251 lbs.

So if I went with an O-320, I'd have to either go on a diet, or fly with half-full tanks.

I saw in another post that Bob's 0-320 uses the dynafocal mount, and that going with a conical mount would save 20 lbs (http://flywithspa.com/panthercave/viewt ... &t=53#p605).

I also noticed that the Sport version's gross weight may increase by 100 lbs., pending further testing (http://flywithspa.com/panthercave/viewt ... port#p1227)?

I was aiming for using an O-320 since I wanted a 150-160HP engine. But I'm open to an O-200 as well. Part of me would be very excited to build a Corvair engine - I've always wanted to learn how to work on engines - but most of me wants to feel secure about the engine keeping my rear in the air .

Anyways, my question is, has the testing for the Panther Sport's gross weight been done, and what is the likelihood of the gross weight going up to 1250 lbs.?

Thanks,
Stephen