Testing the LS Panther

[Tony Spicer]

Thanks, Bob.

This is exactly the type discussion I had hoped we could get started!

The info I was given was an aft limit of 32% MAC or 75.4". That's 2-3" further aft than what you're using.

My Panther with 30 lbs lead on the front of the engine, 4 gal fuel, and 200 lbs in the seat is 74.5"/30.2% MAC. With half fuel it's 74.1"/29.3%MAC, and with full fuel 73.6"/28.2% MAC. To get where you are I'll need either full fuel or more ballast. How about you ballast yours to 75.4" and do a spin series?

Tony

[woolleys]

Tony, congratulations on the AW certificate. Another Panther is born.

Most of the testing of spins in the Lycoming power Panthers have been in the 72 to 73 inch range. The worse case for spins was when I was flying Dan's prototype and it was 3 inches forward of the aft limit. At that location it had good spin recovery manners. With aft cg I did notice a tendency for the stick forces to become very light in elevator below 100 mph. Of course all the Lycoming powered panthers have elevator counter weight instead of the springs. That may account for some of the lightness in the elevator controls. Dan's prototype did have a tendency to spin slightly nose high over the Lycoming powered models. If you have aft CG I would approach spins with caution. One turn at a time. The flatter the spin the slower the rotation and the more elevator input/duration it will take to force the spin and vertical axis together for recovery. I did not notice any lack of elevator control during aft CG moments on Dan's Panther. Dan has flown his Panther with a further aft CG than I did and should be able to give you more data on recovery from fully developed spins.

Now the second phase of building begins, flying your creation. Once again, congratulations.

[Tony Spicer]

Bob,

Great timing on your post as the ink on my Airworthiness Cert is just starting to dry!

What's the furthest aft %MAC at which you've done 3 turn spins? What's the furthest aft %MAC you've flown any of the 4 Panthers?

Thanks again for the informative post.

Tony

[woolleys]

Fellow builders, it's been a while since I've posted any updates on flight testing and flying the Panther. I thought I would just put together a few comments on what I've seen in the 100 plus hours of flying the Panther.

I have had the privilege of flying all four Panthers located here at Haller Airpark. Three have Lycoming 0-320 engines and of course the prototype with the Corvair. Three Lycoming mounted Panthers have fixed pitch props with one running a 3 bladed CATO and two running ground adjustable props; one Sensenich and one Whirlwind. Two are long wing and one is a short wing version. Most of the following comments are for the long wing version and only when there is a necessary comparison to the short wing will that be mentioned. The short wing Panther has about 80 hours of flight time, one long wing has almost 90 hours and the latest to fly has 20 hours. Issues with all three Panthers have been few with minor adjustments on flight trim to get to straight and level. All three required small trim tabs for rudder and aileron. Most work has been to correct avionics issues or instrument errors. All three aircraft are within 3 mph of each at full power and climb rates around 2000 fpm on takeoff. The short wing has the lower climb rate at 1900 fpm. Takeoff distance are all within 500 feet with no flaps.

Takeoffs are accomplished with no flaps and there doesn't appear to be a appreciable reduction in takeoff roll with the flaps. Soft turf runways maybe where the use of flaps may help. All three aircraft transition to the two point takeoff attitude very shortly after full power application with about half forward stick. For some reason my sports version takes a little longer to transition to that attitude. It maybe due to slightly higher negative angle of incident on the sport version. There doesn't appear to be any different takeoff distance when obtaining the two point attitude and letting the tail fly off with neutral stick. Since visibility over the nose is good achieving a two point attitude is not necessary.

For non LSA aircraft you can expect cruise speeds of 151 mph at 8500ft at 60 % power with a burn rate of 7gph. A recent xcounty test of a 300 nm round robin took 2 hrs and 7 minutes with a fuel burn of 14.2 gallons. The Panther appears to have good legs.

Spins testing has seen fully developed spins to the left and right of 7 turns. Additionally semi flat spins have been accomplished with no serious adverse affects on recovery. Spins to the left in all aircraft are a little more accelerated and requires aggressive spin recovery inputs to recover from a spin of 5 turns or more. Spins up to 3 turns can be recovered via a stick release or positive spin prevention flyout. The LSA version spins slower than the sports version and is slower to recover. Flat spins; power added during the spin, requires that the power be retarded to idle and positive spin recovery control input. Recovery is slower due to reduced rotation rate.

As stated in pervious post, stalls are easy to recover with all test Panthers have a wing break left or right. Flaps and no flaps stalls have generally the same wing break per specific aircraft but flaps do have a sharper break at stall.

The rudder is very effective and thus extreme slips can be easily accomplish in both directions. Recommend that you always slip away from the selected tank with less than half fuel. Unporting the fuel pickup is possible during prolonged slip periods.

All three of the Lycoming panthers have installed 50 degrees of flaps. Landing speed control and sink rates are easily controlled with a normal fpm sink of about 400-500ft. Airspeeds of 75-80 mph appears to be excellent for both the LSA and sport version. The Panther gathers speed easily in the pattern and on final, small applications of power is key with small power adjustments. The likely hood of a flap failure is unlikely but I have shot both no flap and partial flap landings. With no drag on the aircraft it must be flown with a very shallow glide path and mostly no power. Landing distance is increased by at least 30 %. You will be surprised as to how much runway you'll eat up with out drag devices.

I have demonstrated x wind landings up to 20 kts steady component in both the sports and LS version. Wheel landings are a must and airspeeds of 80 mph on final appears to handle any gust factor. Transition to the three point position is a bit touchy in that the airplanes will try to fly even down to below 50 mph. The airplane is fairly light and responses to gust quickly. If on pavement, be ready on the brakes to assist in the transition.

The Panther is fun to fly aggressively and will provide good feedback when pushed to the limit. It will remind you that it has limits and when pushed to far will gently remind you of that fact. It is a straight forward airplane with no bad habits.