Panther Sport Aircraft Forums

Thanks Dan and Paul!! That makes a lot of sense.

It seems the single seat Cougar may be my best bet.

Merry Christmas and Happy New Year!!

Hi Guys
First Paul thanks for answering these questions.
Next SPA has never recommended or specifically supported 0-320 powered LSA aircraft. This is due to limited usefull load. I consider 815 lbs empty to be the max "realistic" empty weight for me and a LSA Panther. That gives 300 lbs useful = Me (pre-holiday weight) +chute +10 gal of fuel.I know of one Panther that is right at 815 lbs with a Titan 0-340 (and i want to fly it some day!) The builder / pilot is 60 lbs lighter than me and so has a much more useful aircraft than I would have.
We pushed the gross weight as high as plausibly possible with the long wing. The Panther has 93 sq ft of wing area.To go to 1320 you would need 120+ sq ft of wing area , more likley closer to 130. The Cougar LS will have 126 sq ft .
The best way to get 60 lbs more useful load and 160 Hp lycoming performance is to put in a UL520. These are rated @ 200 hp @3200 rpm, but in the real world my friends (RV and STOL aircraft) seem to be getting the equivalent of 160-170 hp lycoming performance out of them, in a much lighter package.
Or wait for the Cougar and build it/operate it as a single seat. We are working hard to get the "LSA" version 450 lbs of useful with a ultra lightweight lycoming up front!
The other thing to consider is that the long wing Panther with any engine will outperform most aircraft at altitude. look at the real performance numbers of the Panther near sea level and compare with other aircraft you are flying , and you will get a idea of how it will compare at your field ele.

Happy Holidays to all

Wow thats some good info! Thanks Paul and Chuck.

Lowrider,

Certainly didn't mean to imply anything about anyone being critical of the Panther.

Panther was designed to handle various engines for various conditions and preferences.

Unfortunately, the LSA regulations cause some design limitations. Outside of LSA you have more choices. Who knows, sometime there might be another option for a larger/different wing, but there is nothing on the drawing board or in discussion currently.

We hear the 1320 lb question a lot at airshows, and find that a significant number of people don't understand how max gross weight, stall speeds and wing area relate. Just wanted to explain some of the design tradeoffs required.

The engineer in me likes to be specific and explain reasons

I was not being critical of the Panther, I like it and it's performance but would like the extra gross wt to make it more capable with the 0-320. It's not uncommon in the Summer out West at high elevation fields to find density altitudes that are significantly higher than those found in the East. I've always liked the Corvair but I don't think it's enough umph to operate successfully in these conditions. Extra wing and little less roll rate wouldn't bother me at all and would still make neat plane. The extra 40+ hp would be real handy.

The Panther was designed for a wide range of engines, and the Cougar will be similar, but leaning more to the higher horsepower engines. Lycoming O-233, O-235, O-320, Continental O-200, O-240, Franklin, Jabiru 3300, UL350, and Corvair 3.0L and 3.3L are some of the most popular currently supported engine choices.

Since SPA started out supplying components for Corvair, it was a given for it to be one of the first engines for the Panther. Having said that, SPA is also a dealer for other engines, UL, Superior and Titan being some that come to mind immediately. Jabiru and their firewall forward kit is handled by Jabiru North America, they have extensive knowledge of the Panther, as Ben is currently flying one.

The lightest engines are the Jabiru and UL. Corvairs, O-200 and O-233 are in the next weight range, then O-235 and O-240 and finally O-320 being the heaviest.

Most engines are going to burn nearly the same gallons per hour when you throttle back for the 138mph at max continuous rpm regulation for LSA. Some engines you just have to throttle back more than others.

At each horsepower level, all the engines in that HP range is going to be similar on fuel burn, there will be some minor differences, but usually within 10-15% even between a full electronic injection and a standard carburetor. There are no truly magical changes to internal combustion engines on fuel burn per HP until you get into turbo/superchargers and/or exotic injections like water/ethanol or Nitrous. All of which starts adding cost and complexity.

The big differences on fuel burn come when you start cruising at higher speeds. Obviously the faster you go, the more horsepower required, thus more fuel burn.

You can contact SPA after the holidays and get current prices for the engine options provided by SPA.

Some of the lowest cost (<$10k approx.) engines are usually mid-time lycoming and continental engines that you buy and rebuild/fix yourself, but requires some knowledge to make sure you get a good engine to start with, or it can get expensive quick. Jabiru and Corvairs are at the next level ($10k to $18k approx.) for new/nearly new. Prices are usually higher from there. Don't hold me to these prices as they can vary a lot due to condition of used engines and/or variations in the dollar for imported engines as an example.

As to aircraft size/ pilot size if you are under about 6'3" most likely you will fit. We have had pilots upwards of 6'5" or 6'7" in the aircraft and close the canopy, but that really depends on individual body build. I highly recommend trying one on for size either at a show, or possibly a builder near you. With at least 18 rudder pedal positions and around 56 seat back positions, a Panther can easily be tailored to fit a lot of pilots.

Chris said:

For me now, I'm at the stage where I'm trying to educate myself on options and plan out financially the prospective build. Compared to the lycoming what differences?? Weight and power gain fuel burn etc. again if there's a reference elsewhere I'd appreciate a point in the direction.

Chuck says...
There is a plethora of information on the Corvair and comparisons to the closest competitors over on the www.flycorvair.com website. Spend the time reading through the blogs it will be worth your time to jump in and dig through.

Thanks Paul, that was another question is a pilot my size fitting and being able to go fly for more than 10 minutes! Lol.
So back to engine options...I will be honest and say majority of my flying experience is on turbine powered helicopters. So I'm trying to educate myself on engine options. I read where Dan mentioned that the panther and I assume cougar are designed to accommodate a variety of engines but made for a corvair. For me now, I'm at the stage where I'm trying to educate myself on options and plan out financially the prospective build. Compared to the lycoming what differences?? Weight and power gain fuel burn etc. again if there's a reference elsewhere I'd appreciate a point in the direction. I also appreciate all answers in advance!

It is physically impossible to increase the max gross weight to 1320 lbs and still keep the LSA stall speed with the current design of the Panther.

Stall speed is a combination of 4 things, air density, wing area, weight and max lift coefficient.

Air density is not something we can really change obviously.

Max lift coefficient is set by the airfoil, most airfoils that work well at higher speeds use high lift devices to increase the max lift coefficient, but FAA regulations do not allow the use of high lift devices to lower the stall speed for the LSA category. They can be used, just not counted against stall speed. Most airfoils have very similar max lift coefficients without high lift devices. While there are some highly cambered airfoils that have great max lift coefficients, they come with penalties of high drag, and large pitch moment changes.

Wing area is the only thing that can really be changed, the LS series increases wing area for the stall speed. However, increasing wing area has other drawbacks: More weight because of heavier structure for the larger wing, larger tail because of the larger wing, more drag, usually causes a decrease in roll rates, and makes it harder to fold the wings and trailer.

Everything is a compromise to give the best performance for as many conditions as possible.

Unless your mission is to beat a high powered RV-4 or Panther in nearly all regimes, there is no reason you can't have just as much fun with a smaller engine. Bob just flew my Panther last night, (see his comments in the flight ops section). He had one key comment after flying it, "One great thing about Panthers, they all fly well regardless of the engine.". He did all the aerobatics you would expect for an aircraft with no inverted fuel and oil systems.

Dan and myself both tip the scales at more than 225 lbs and are around 6ft tall. That was one of the design criteria, fit larger pilots than nearly any similar aircraft.

That was next question I had Joe. I'm a 225 pound 6' tall guy. Of course I need to shed a few pounds but am wondering if there are prospects of an increase in go for sport version?
And I know Dan, intent is keep weight and cost down to fit a niche'. I'm impressed with everything I've read and heard and seen of the panther. I have never tackled a build project but am almost ready to pull trigger and attempt a tail kit for starters. Also, I'm very interested in the corvair engine. Bare with me on perhaps some dumb/ or redundant questions. I'm reading as much as I can as I go here and I'm sure some answers may be posted elsewhere here. Thanks in advance guys!
Chris