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pete(at)usjabiru.com
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 Posted: Fri Jan 19, 2007 6:27 am Post subject: Lightning Flight Report |
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Hi All,
Here is Buz Rich’s flight report originally posted on the Lightning list last July
Pete
From: N1BZRich(at)aol.com [mailto:N1BZRich(at)aol.com]
Sent: Wednesday, July 12, 2006 2:15 AM
To: pete(at)usjabiru.com; vettin74(at)yahoo.com; ben(at)usjabiru.com
Subject: Lightning Flight Report
Pete, Nick, Ben: Give me some quick feedback tomorrow morning (Wednesday before I fly home) before I send this out to the two list.
Buz
Hi All Esqual and Lightning talk members,
I must apologize for not getting this message out sooner. I flew my Esqual LS (LS = Lightning Stuff) to Tennessee last Thursday, 6 July, to fly the Lightning prototype (N233AL) and to help with writing the pilot's operating flight manual. It has been a busy but, as always, a fun time. My flight to Shelbyville was non stop in 3.6 hours, averaging 154 mph block to block (had a small head wind most of the way). Total statute miles is 554 and my fuel burn averaged 5.5 gallons per hour. Not too bad.
When I arrived in the SYI area, Nick was airborne in 233AL on a "combat air patrol" waiting on me, and needless to say he immediately "was on me" and kept the "MIGS" at bay the rest of the way to "home plate". It would have been nice to "play for a while" but after 3.6 hours I needed to land ASAP.
I flew the Lightning solo late Friday morning, 7 July, 2006, and had a great flight. Outside air temp for take off was already 85 degrees. Most of my flight testing was done at 5,000 to 6,000 feet and the average OAT up there was 72 degrees. I should have noted the density altitude, but failed to do so. Needless to say, it was high. I topped off 233AL for the flight (22 gallons total) so I estimate a take off weight of 1230. Remember, 233AL being a prototype is probably 100 pounds heavier than production kit Lightnings.
Take off in the Lightning was short and quick. At Shelbyville's field elevation of 800 feet and 85 degrees, the Lightning was airborne in approximately 500 feet. Runway lights helped me to estimate this distance. I used 10 degrees of flaps for takeoff and after rotation I raised the flaps accelerating through 75 and used 87 mph (Vx) for my initial climb. Passing the end of Runway 18, I started a left turn and let the nose down slightly to let the speed climb to 100 mph which is Vy. Initial rate of climb was 1200 feet per minute by the VVI and when I got to 5500 feet it was showing 800 fpm. Total time to 5500 feet was 5 minutes. That averages 1000 fpm in my book. Not bad for a hot day.
After a few quick clearing turns to check the area (no MIGS) and to get the feel for the airplane, I started doing some clean and dirty stalls. The airplane flies with the ball centered with no tendency to roll when trimmed hands off. However, I did notice that the right aileron is up about 1/2 inch in straight and level flight. Overall I did a total of ten stalls each, clean and dirty, to make sure I had those numbers accurately documented. Clean stalls, as in the Esqual, are quite nose high, but the nose drop, when it comes, is not violent at all. There is a slight buffet, then the nose slowly drops. There was a tendency for the left wing to drop which was easily corrected with rudder. My assumption is that the left wing low was due to me sitting on the left side. The clean stall occurred at between 48 and 50 mph. Remember, I was not at the 1425 gross weight or the 1320 gross weight for the Lightning Sport Plane. Flaps down stalls occurred at 34 to 36 mph. (Note: These airspeed numbers are from the EFIS now installed in the Lightning. We already knew that the Lightning's standard "round dial airspeed" reads low when at the slower speeds. The EFIS in 233AL reads exactly what 31BZ's EFIS and back up airspeed read when the two airplanes are in formation.)
The Lightning's flaps go down a full 45 degrees as opposed to the Esqual's 30 degrees full flaps. I did some of the flap down stalls at 45 degrees and some at 30 degrees just to get a comparison. I really didn't note any difference in stall speed, but there is a big difference in drag. Meaning the speed drops much quicker at 45 degrees and when you power back up to recover it takes much longer to get a climb going. This could possibly be a problem on a last minute go around with 45 degrees of flaps - 30 degrees is much better in my estimation. Just a thought, but Lightning builders might consider changing the flap actuation system to only go down 30 degrees. Any way, the dirty stalls were not nearly as nose high, the slight buffet was there to "talk to you", and the nose fall was gentle. The tendency for the left wing to fall off was much less.
With the stall series out of the way, I could now play with the Lightning to better evaluate how it performs. One maneuver I like to do when evaluating aerobatic biplanes, is to put it in a 3 G level turn at some airspeed to see if the speed falls off quickly, stays the same, or perhaps increases. This is my way to see how quickly an airplane bleeds energy or to measure excess energy. An interesting thing happened with the Lightning while doing this maneuver. At 2900 rpm and 120 mph, in a 3 G continuous level turn, the Lightning just keeps on holding 120 and pulling 3 Gs. Pretty impressive. But what is more impressive is that if you push the power up the Lightning accelerates while still pulling 3 Gs. No energy bleed here - definitely excess energy. The wing makes the difference.
Speed runs at 5000' were about what I expected based on what Nick had briefed me on. His initial flight test for performance data was done with a Sensenich 64ZK54 (54 inch pitch prop) and were done during this past winter and spring. At that time he was seeing 175 true mph at only about 3050 rpm, and close to 190 when at full throttle - but was pulling the throttle back to keep below the 3300 max rpm. Now, using the new carbon fiber ground adjustable Sensenich, he is still experimenting with the correct blade setting for optimum speed performance. Add to that the really hot high density altitude and the speed numbers are lower than a Lightning builder can expect with the correct prop setting. Here are the numbers I saw: 2850 = 150 true mph, 2950 = 157, 3050 = 165, 3150 = 170, and 3250 = 177. There is no doubt in my mind, that the correct pitch prop on a standard day will increase all of these numbers by at least 10 mph, probably more.
I like the way the Lightning flies more than I like how my Esqual flies (and I really like 31BZ). Here are the main differences that I noted (and these differences showed up again in a later formation flight). The Lightning accelerates slightly faster and decelerates slower than 31BZ. The different wing (shorter and different airfoil - a NACA 6200 series) has less drag than the longer Esqual wing. This shorter wing also results in a smoother ride when down low in turbulence. Pitch forces are light in both aircraft, but slightly lighter in 31BZ (which is a lighter airplane). Roll forces are slightly less in the Lightning (shorter wing). Roll rate is hard to accurately measure, so I will just go on my past experiences and say that it rolls faster than a Cessna or Piper, and slower than the RV series or aircraft. I have only flown the RV-3 (I did the stall and spin test for a friend) and it was a great airplane. Roll is way slower than my Pitts, but then most everything is, expect the fighters I flew in the Air Force. I would estimate roll rate at about 120 degrees per second, but then I could be off. What ever it is, it is nice. Pitch and roll forces are well harmonized at 120 mph and below. However, as speed increases, pitch forces only slightly increase while roll forces go up a lot - just like most high aspect ratio aircraft with relatively small ailerons. >From what I remember of my RV-3 time, as speed increased, roll forces stayed light, but pitch forces went up a lot. Again the different wing design (smaller span with larger ailerons) would cause this. Bottom line, the Lightning is a delight to fly. A sporty feel with very spirited performance while being very economical to operate. Wow!
Landings are actually easier than the Esqual in that the Lightning wing seems to "groove" more, meaning that wind gusts and turbulence have less effect on the Lightning. I made three landings, two using 30 degrees of flaps and one with 45 degrees. You can fly a steeper approach with the high drag that the 45 degrees gives you, but I feel that the 30 degree flap setting is a better choice base on my comments above about go arounds. Touch downs are easy and there is not much float if your airspeed is on target. I used 60 mph on final in the Lightning and I always try for a full stall landing. Once on the ground it rolls out straight and you can easily make a 1000 foot turn off. If you want to use lots of brakes, you can stop much shorter. Piece of cake.
Friday afternoon Nick and I flew a close (fingertip) formation flight to gather some additional data to use in developing the performance charts. N31BZ is equipped with fuel flow and manifold pressure (233AL, being a prototype does not have this equipment) and we needed this information to accurately predict cruise and range data. I had a copilot with me to write down all the data, so all Nick and I had to do was accurately fly specific speeds in close formation. At various speeds we wrote down rpm, IAS, TAS, FF and MAP. Later we could compare these numbers and more accurately predict 233AL's fuel flows and manifold pressures. The results are now in the Lightning's flight manual.
I will close with a bit of good news for those of you that want to build a light sport compliant Lightning. Nick and I have figured out a way for you to have the neat gear leg fairings and the latest style wheel pants. All you have to do is install a drag chute. The Lightning is really going to be that fast.......and economical too.
Blue Skies,
Buz
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N1BZRich(at)AOL.COM
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| Posted: Fri Jan 19, 2007 6:36 am Post subject: Lightning Flight Report |
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Hey great - Pete beat me to it. And apparently I posted it on both list. After reading it I would be glad to answer any questions that any of the list readers have.
Buz
[quote][b]
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pequeajim
Joined: 03 Sep 2006
Posts: 708
Location: New Holland, PA
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| Posted: Fri Jan 19, 2007 6:03 pm Post subject: Re: Lightning Flight Report |
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Nice flight report and thanks!
Jim!
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