Weight considerations with O-320

[Lowrider]

I'm all for light weight in planes, pilots and engines and the cheapest is for the pilot to loose weight and perhaps healthiest. I grew up in the 60's with a '36 Plymouth Coupe and a 409 Chevy, GTO, 442 and it's hard for me to shake the idea that cubes rule. That aside, if there was an adequate market and we could get FAA out of the process there would be a 150 lb 200 hp $3K airplane engine that ran on high test car gas, but there isn't a market to support the research and development.

Last century technology in the 0-320 can certainly be bested by more modern engines and I'd have to side with Tony, but...if you have a mid-time 0-320 in the back of the hanger it's hard to pass that up in favor of new mega bucks but lighter engine even if it does perform the same at 10,000'.

[Exhaust guy]

Here are some thoughts on using the 0-320 in the Panther. The E2D dyna focal is listed at 268 lbs. This weight is from days gone by before light wt. starters and alternators, taper fin cylinders, and magnesium sumps all of which can be installed to bring the weight down from 268 to the 240-245lb range. The sky tec starter is @ 61/4 lbs. I'm not sure about the B&C 8.5 amp alternator but I think it weighs about 1/2 of a 20-40 amp up on the front. The starter ring gear can be modified by shaving off the V belt drive pulley and drilling lightning holes in it. I just did one and it went from 6 3/8 to 5 lbs, or Sky dynamics has a magnesium one that weighs less. Changing out mags to P-mags and using auto plugs instead of standard ($30) aviation plugs will reduce another 6-7lbs. The magnesium sump is 7 lbs lighter than the standard sump.
On my last project I built a set of intake tubes out of aluminum and saved 2 1/4 lbs. If I remember correctly the taper fin cylinders are 2lbs each lighter so save another 8 lbs. there. One more area is the oil screen vs. the oil filter adapter and oil filter. I would elect to use the standard oil screen and housing which is @ 1-1/5 lbs.
Another big area is using carbon fiber plenums instead of standard engine baffling. Take off at least 5-6 lbs and the plenums do a great job at cooling.
The bottom line is simple. The 0-320 can be made a lot lighter than original--it just boils down to how much money you are willing to spend to get rid of each pound of weight. Any of the above mods mentioned do not take away from the safety or longevity of the 0-320. I hope this info helps when you need to decide on your Panther engine. Larry Vetterman

[Tony Spicer]

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.

Purely for the sake of discussion, let me throw a few things out with regards to more horsepower. Typically, what you get with more horsepower is an increase in engine weight, higher fuel consumption, better climb, and a faster top end. My guess, and I'll be happy to bet a case of beer on the outcome, would be that a Jab or ULPowered long wing Panther would get off the ground every bit as fast as a short wing with an O-320. And it would come very close to matching the climb rate.

Any takers?

Tony

[danweseman]

Good points

The short answer is
Gross weight testing has not been completed
Aft CG limit has not been tested.
These will both effect the approved gross weight
1250 lbs max Take off weight with no intentional spins or acro is VERY likely after testing.

careful planning and choices in how to equip , and where to install components like battery's transponders etc. will ensure a proper CG range .As more Panthers are completed we should have better information on these items
The Panther, and almost all single seat aircraft are limited in useful load. I think the Panther has one of the highest in its class.
Bobs airplane will likely end up around 850 lbs with paint. It is not particularity light or heavy .
The notable items with extra weights next to them. Note these are approx weights for discussion purpose

Wide deck dynafocal mount 0-320 (+5-15 lbs depending on exact engine and source of information)
Whirlwind ground adjustable prop (+8 lbs over typical 2 blade wood)
full size Cleveland wheels and brakes (+4 lbs over standard matco with 5x5 tire)

Bob used two notable extremely lightweight components
LiPO battery ( -10 lbs over typical battery)
vacum pad lightweight generator (-4 lbs )

hope this helps some

[blueisthenewblack]

Reading Dan's post more closely:
http://flywithspa.com/panthercave/viewt ... port#p1227

You can already add fuel up to 1210 lbs., which would allow me to fly with full tanks at a bodyweight of 220 lbs., but just barely .

Sorry to beat this topic to death. I think this is really just my latest excuse to try and find some reason why I should not build a plane, when I really just need to decide on a kit, buy it, and get going.

[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