Paul Salter's Panther N908XP

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at7000ft
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Re: Paul Salter's Panther N908XP

Post by at7000ft »

Thanks for the info Paul and Bob, nice work, concerning climb rate at 8-9000+ ft DA, has anyone done a similar test with an O-320 Panther? My airport is always between 8-10,000 DA and am still debating a Corvair vs. an O-320 (the Corvair sounds so much better, and I already have one).

Rick H
Rick Holland
N6819Z

psalter
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Re: Paul Salter's Panther N908XP

Post by psalter »

Here is some additional information to what Bob has just posted.

On the Rate of Climb tests, Bob would start a climb around 1000 ft, and get settled at the test airspeed max power, we started a timer at 1500ft and ended at 3000 ft. On that day, the density altitudes we were testing at were from 2100 ft (1500 indicated) to 3600 ft (3000 indicated).
Rate of climb.pdf
The above chart shows the rates of climb for different airspeeds. Between 70 mph and 100mph we had rates of climb between 1040 and 1130 about 8% difference. As you can see, from 75 mph to 95 mph there is only about a 2% difference in rate of climb.

The 2 sets of marks are from 2 different ways of calculating the rate of climb. The timed one is the standard stop watch and altimeter method. The GRT derived is from downloading the flight data, going to the section of the data for the airspeed we were testing and averaging the vertical speed values. Writing down the start and end times based on the display clock helps in finding the correct location. For all of the tests, the difference between the 2 methods was less than 30 FPM, and for most, it was less than 10 fpm.

So, that works out to a Vx of around 71mph with a rate of climb approximately 1040 fpm. Vy is a bit tougher, because of the little spread between the rates of climb. I will probably use 95 to 100mph for Vy just because the higher speed will help keep the engine cooler, but at no time during the tests did the cylinder head temps get above 380 degrees.

This is similar to what Dan found with the tests on the prototype. We believe that the reason for the fairly flat curve is due to the fact that as you lower the nose (higher speed), the engine RPM increases, and thus you have an increase in available Horsepower. Some of that is also due to the fact the propeller is also more efficient as the speed increases up to around 140-160 mph.

This data will vary on your particular engine, propeller and aircraft weight. This is only good for my aircraft.

During tests a couple of days later, Bob climbed to about 9500 ft indicated 11,400ft density altitude. Between 9000 ft and 9500ft indicated, the average rate of climb from the GRT data was still about 550 fpm at an average speed of 105 mph indicated. This altitude was picked for several reasons, one of which is 10000ft is the max LSA altitude, and lack of onboard oxygen. Dan's Panther was been to about 13,500 ft with the 3.0 L Corvair and still hadn't reached the service ceiling.
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Paul Salter
Team Panther
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woolleys
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Re: Paul Salter's Panther N908XP

Post by woolleys »

A report on the on going testing of Paul's corvair power panther. I have put some 3-4 hours on Paul's Panther and can say that it continues to prove that it is a very capable airplane. Most of the hard flight test profiles have been completed and the excellent design features of Dan's aircraft continue to shine.

Extensive testing of the low speed characteristics and aerobatic qualities have been defined and some of the observed handling observations follow. Additional cruise data has been collected with cruise flight up to 9500 feet. All reference numbers are in MPH are taken from indicated airspeed observed.

Takeoff and climb with the 3000 cc corvair from our turf runway sees about a 500-600 foot takeoff roll with a climb rate of 1000 fpm at 105 to 110 MPH. Average climb rate at this speed is around 700 FPM and with a climb to 9500 feet resulted in a climb rate of 450 FPM at 105 MPH. Cruise speed at that altitude was 133 MPH at 3000 R's. Top speed at that altitude was 142 MPH at 3380 R"s. Paul has installed an autopilot with altitude and heading hold and it works extremely well. A nice addition if lots of Xcountry is planned.

Extensive stall and spin profiles were completed with all stall recovery being benign and recovery with a slight release of back pressure. All of the Panthers I have flown show the same characteristics with very little airframe warning prior to the actual stall. With Paul's Panther, the left wing has a tendency to drop first and holding the stick full aft, took about 15 seconds for the left wing to achieve 45 degrees of bank and 20 degrees nose low. The aircraft was attempting to recover with a continues nose drop and recover. Spins were completed both left and right from full developed to prior to one turn recoveries. All recoveries were predictable and easily flown out during every phase of development. Hands off recovery up to 3 full turns were used. This technique was very predictable but resulted in a slightly longer recovery period with steep nose low attitudes during recovery.

Paul's Panther is a joy to fly during aerobatics. The smooth power delivery and the reliable Ellison carb. provides excellent response. All maneuvers can be completed under 3 G's with a rolls rates predictable for the long wing versions. To show the nice handling qualities of the this Panther, I have entered loops at 115 MPH with full power and coming over the top at 55 MPH and have applied full aft stick. The airplane gives a slight shutter and tucks it nose to the vertical down line and accelerates smoothly away. One point for the aggressive flyers. During high G maneuvers, in the 4-5 G range, if you get into an accelerated stall condition and do not release some back pressure, the airplane will have a tendency to try and break hard to the left; almost a quarter snap. Recovery is easy and immediate with back pressure release. The airplane will give you plenty of audio warning with a severe rumble from the aft end of the aircraft.

Landings for the Panther are smooth and result in about a 700 foot roll on turf have been using full flaps with a 70-75 final airspeed. Wheel and three point landing are easily done with excellent elevator control. Partial flap landing have been completed using the same airspeeds. The natural tendency of the airplane to float and with little drag it does not want to slow or come down. Long and flat approaches will be the norm when using minimum flaps. Cross wind landings up to 15 MPH have been demonstrated with excellent response and handling qualities. Tracking on the ground with Dan's single link steering rod is excellent; highly recommend this for the tailwheel versions of the Panther.

The corvair powered Panthers continue to impress me with the performance. As I related to Paul and Dan, match a constant speed prop with the 3300 or 3000 CC models and it might make an old power hunger guy like myself smile and consider trading in my big bore Lyc's.

Paul has built a beautiful airplane with flies like it looks. I appreciate the chance to fly it and put it through it's paces. .

woolleys
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Re: Paul Salter's Panther N908XP

Post by woolleys »

Had the honor to fly Paul's panther yesterday afternoon. What a sweet flying machine. The sortie was conducted at Haller Airpark. Winds were calm and the temperature was in the sixties. The sortie was a on going flight test with the purpose of exploring stalls, spins and aerobatics. The sortied lasted about 40 minutes and was conducted between 3000 and 4000 feet.

I had not been in a corvair powered panther since I had flow Dan's panther. All of my panther time has been with the Lycoming powered machines. The engine and prop combination was extremely smooth and had excellent and linear power delivery; the Ellison carb. operated flawlessly. Every Panther I've flown has almost identical handling qualities. Elevator and aileron response are almost identical and only minor differences have been noted. These mainly due to CG locations and weight. The Lycoming powered versions feel most robust and the corvair machines have a light nimble feel to them. The higher horsepower Lycoming ones are power dominated with high climb rates and more vibrations. The smoothness of the corvair power ones are almost turbine smooth; very nice.

The departure was from a firm turf runway and with about 13 gallons of gas the panther lifted off about 700 feet of takeoff roll. Climb established a 110 mph with a rate of around 1100 fpm. At mid field downwind the panther had climbed to about 1000 feet. Two turns over the airport saw 2500 feet with some steep turns of 60 to 70 degrees of bank. Good response and plenty of power to complete the maneuver. Stalls were accomplished with no flaps and full flaps. The machine had a slight nose dip and right wing drop and recovered with a slight back pressure release. On one stall the stick was held in the full aft position and the airplane tried recover but keep dropping the nose. After about 30 seconds the nose had fallen to about 20 degrees nose low and 45 degrees of bank. All recovers was a matter of releasing back pressure.

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Re: Paul Salter's Panther N908XP

Post by brucegray »

Very Nice Paul!

Look forward to more stats and more so can't wait to hear you behind the stick, huh! Have a great holiday and hope that TW endorsement gets knocked out during the holiday, you'll be ringing in the New Year with a flight in your New Airplane.

Bruce Gray # ? cat will be out of the bag soon

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Re: Paul Salter's Panther N908XP

Post by bob_arthur »

Thanks Paul!

That helps a bunch.
I am going back-and-forth between the 3.3 Corvair and the 160 lycoming.
I want great performance but I definitely don't want the extra weight of the Lycoming.

Decisions, decisions!



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Re: Paul Salter's Panther N908XP

Post by bob_arthur »

psalter wrote:Bob,

Stall speed is showing right around 51mph True, but that was to be expected as we had tested that on Dan's. And set the max gross weight to meet that LSA requirement.

Max speeds near level flight has been has been in upper 160's low 170's ground speed but, I haven't crunched all the numbers yet to get a definitive number, but that is again similar to Dan's.

We have not done sustained max rate of climb tests yet, but 1500 fpm has been demonstrated pretty easily on mine, Dan's we had seen near 1700fpm with the 3.0l.

As mentioned before, Dan's prototype (as originally tested) and mine are virtually identical with the exception of about 20lbs in weight. Mine is completely production representative, Dan's is about 95% production representative. Also, mine has the Ellison, and Dan has the MA3 carb. Of course, now that we moved the 3.0l to mine and he is testing the 3.3L on his, rate of climb numbers are sure to increase for him.

As to the rating, the instructor and I have been waiting out the weather, we have had low ceilings 700-900 ft and occasional rain/drizzle for the past 2.5 days, and it looks to be more of the same until possibly tomorrow afternoon.


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psalter
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Re: Paul Salter's Panther N908XP

Post by psalter »

Bill,
The seat back is in the 3rd or 4th hole from the rear on the bottom and about the middle of the upper brackets.
Paul Salter
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ynkster
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Re: Paul Salter's Panther N908XP

Post by ynkster »

Great build, Paul!! Where do you have your seat set? Good luck on the weather!!

Bill Mosher #46

psalter
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Re: Paul Salter's Panther N908XP

Post by psalter »

Bob,

Stall speed is showing right around 51mph True, but that was to be expected as we had tested that on Dan's. And set the max gross weight to meet that LSA requirement.

Max speeds near level flight has been has been in upper 160's low 170's ground speed but, I haven't crunched all the numbers yet to get a definitive number, but that is again similar to Dan's.

We have not done sustained max rate of climb tests yet, but 1500 fpm has been demonstrated pretty easily on mine, Dan's we had seen near 1700fpm with the 3.0l.

As mentioned before, Dan's prototype (as originally tested) and mine are virtually identical with the exception of about 20lbs in weight. Mine is completely production representative, Dan's is about 95% production representative. Also, mine has the Ellison, and Dan has the MA3 carb. Of course, now that we moved the 3.0l to mine and he is testing the 3.3L on his, rate of climb numbers are sure to increase for him.

As to the rating, the instructor and I have been waiting out the weather, we have had low ceilings 700-900 ft and occasional rain/drizzle for the past 2.5 days, and it looks to be more of the same until possibly tomorrow afternoon.
Paul Salter
Team Panther
Engineer and Builder

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