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Pilot Report - Lightning

 
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dashvii(at)hotmail.com
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PostPosted: Tue Aug 01, 2006 5:11 pm    Post subject: Pilot Report - Lightning Reply with quote

Ok, I'll bite. I've got several hours in the Lightning now. Hopefully this won't bore all of you and I'll try not to be too technical. Let me start with a little history on the Lightning. The Lightning was developed around the same idea as the Esqual, a light, fast, fun, and affordable sport plane. The Vol Medici company that marketed the Esqual sold off the company and (so far) stop producing the Esqual kits. Jabiru USA was the US importer for Esqual. This aircraft complemented the Jabiru line of aircraft as well as providing for a low wing alternative to the high wing Jabirus.

The wing of the Lightning was designed much like the pressure recovery wheelpants. The wheelpants are from the RV series of aircraft and modified to suit our own needs. RV borrowed the design from Cessna. The idea is that there was a better way to fair the landing gear that would result in less drag. At the point where the airflow starts to detach from the surface of the gear, the shape would create a suction that would reattach the boundry layer. The wing was designed as a kind of teardrop shape with concave trailing edge shape. It is a high laminar flow wing.

Now the wing that is on the Lightning is kind of a reverse engineered wing that was originally on the Esqual wing. For various reasons that airfoil was traded for a different one and the molds were destroyed. The new Esqual wing is more of a Clark Y "Hershey Bar" type. That wing will allow for a shorter takeoff run, but at the same time will float forever if you come in hot and get in ground effect. In Europe, operating out of grass strips the lower takeoff run and slower liftoff speeds were more desirable on a sport plane than all out speed. The Lightning wing is whole different beast. The speeds are higher on the plane for takeoff and landing. The flaps work much better than the Esqual in that they provide the needed drag where the Esqual is mostly lift and a means of not accelerating when pointing the nose down, kind of more like a speed brake. As with any glass plane it will accelerate rapidly when the nose is pointed down in a clean configuration. On one particular flight test in an Esqual I tested for aileron flutter after finding and tightning a loose aileron. With the power to idle in almost a vertical down line the Esqual will quit accelerating and hold about 185-195 mph indicated. The Lightning will eagerly pass through 200 and rapidly accelerate past Vne.

There were two "hybrids" and one prototype aircraft. The first hybrid, which we refer to as the "Frankensqual" is an Esqual fuselage with the prototype set of Lightning wings. It has an old 80hp Jabiru 2200 engine and will do 160mph flat out! The airplane is about twice as pitch sensitive as the Lightning with much lighter feeling on the controls. It has a far aft CG because of the light weight of the engine and had each wing that was 60lbs. heavier. Very impressive performance and after about 15 minutes of flying it you get used to the sensitivity. The next was Buzz's plane which tested the wheelpants, gear leg fairings, and the cowling for the lightning. Buzz built the fastest Esqual in the world, by about 40-50mph! In fact, his plane is similar in performance to the Lightning. In an all out speed comparison at 5,000 feet the prototype Lightning pulled away from Buzzes plane by about 1-2 knots. The pitch of the prop wasn't set to the optimal level on the prototype at the time in its defense. Some of the speed can certainly be attributed to Buzzes craftmanship and attention to detail. For those of you who have seen it you know what I mean. Getting everything faired over and making sure that you have a tight fit and smooth finish amounts to drag reduction, and superb looks. Buzz also got custom leather interior and foam fitted seats put in. I encourage any of you builders to do something similar. The cloth seats are comfortable, but those leather/foam seats just really feel nice and make for a comfortable ride.

The prototype, as did Greg Hobbs' plane had a thicker tail section which was the result of a miscommunication. The fiberglass layups were extremely thick in the tail which resulted in a much heavier fuselage with an aft CG. While this is great for speed, it is horrible for loading arrangements and total useful load. All of the newer planes have a lighter fuselage which should mean better takeoff performance and acceleration. The prototype also had an early horizontal stabilizer that was (I think) 6lbs heavier per side. It has since been replaced with a production tail. Nick is continually finding little ways to improve performance, looks, functionality, etc. This is as much his baby as anybody's and he continually tweaks things. The prototype eventually got to a little over 200mph TAS in level flight. That was at greater than 3300 rpm though.

Now on to the Pilot Report:

First off, approaching the airplane you notice that it is a very nice looking plane. The complex curves of the composite aircraft look very similar to that of a Lancair or Cirrus. The plane is smaller than either and looks fast just sitting there. A walk around is similar to any other light airplane with attention to the composites. I like to get down to eye level with the surface and look for any chips or cracks that may indicate delamination. So far I've never found any, which is the way it should be for a newly built plane, but it is a different type of a thing than you look for in a metal airplane. I pay careful attention to the tail area and stabilizers. The wings are extremely strong and both main wing spars cross through the fuselage, under the seat. The rear of the wing attaches to the fuselage without a carry through structure.

Getting in the airplane is accomplished by climbing up on the wing, being careful to avoid stepping on the flaps. The sides of the plane are fairly low and you can easily throw a leg over into the cockpit. At this point you want to step into the seat and then your other leg goes over and into the floorboard. Once seated you find that there is adequate room for two adults to fit comfortably, even for long trips. The center console does get in the way, keeping you from moving the stick to the stops because it hits your knees. Future planes will have a console that terminates at the edge of the seat. This should fix the problem. Sitting in the plane the seats are reclined a bit. I find that on a long trip this made me want to raise my head forward and that was uncomfortable after a while. If the plane is going to be used for some long trips I would suggest fasioning some type of head rests. This of course would limit the useful load some though. The visibility is incredible with that bubble canopy. The canopy itself is much clearer and free of distortion when compared to the Esqual. Another thing is that the Lightning has a longer nose and gives a difference perspective than flying in an Esqual.

With two on board and 10 degrees of flaps the plane will Flying Greg's airplane I found that the airplane was very responsive. The airplane will rotate the nosewheel to a degree or so at about 50 mph and will hop into the air at a little less than 60mph. Once airborne a speed of 80mph will give you greater than 1000 feet per mintue climb. The airplane is nimble, about 90 degrees of rolls per second. It has a really nice feel to it. The pushrods give a direct feedback from the plane and have a firm, but not heavy feel. This gives the plane a sporty feel, but not a twitchy overly sensitive feel. In a climb with high RPM and low speeds the plane requires some good rudder input. Again the controls are firm, but not heavy. Greg's airplane had a trim control issue at first which caused us to run out of trim and the nose would still fall at certain speeds. The plane can be flown in all operating configurations without trim, but it is more comfortable and easy to fly with the use of trim. The plane can be flown hands off when in unaccelerated steady-state flight in trimmed configuration. Again, on a long trip a dual axis autopilot would be nice to have, especially when coupled with the Grand Rapids EFIS. That would even do virtual approaches on autopilot.

Landing speeds seemed to fall right in place if you can enter the pattern at no more than 110mph and slow to around 100 on downwind. The plane flies a nice at the 65mph final approach speed. The plane seems to have good rudder control and excellent aileron control authority in these lower speed ranges as well. Landing is more challenging in some ways than the Esqual. The Lightning doesn't really float. It is similar to a high performance Mooney in that the laminar flow wing flies to a point and then it stops. The trick is to round out the flare with a slight nose high attitude just as you reach the stall speed of between 45-55mph depending on configuration. I liked using 20 degrees of flaps instead of 30 degrees. For me it seemed to give a flatter and better feel on the approach. 30 degrees of flaps led to a good decent angle and although the plane will land just as smooth, I felt that this wing wanted to fly onto the runway.

Flying Greg's plane out to the Tucson area we covered around 500 miles in a little over 2.7 hours. We burned approximately 6.0 gph at 2950 RPM (slightly high side of cruise RPM) Greg admitted that the jets weren't quiet tweaked as well as they could be and that a slightly lower fuel burn would be in the near future for his plane. We also didn't have the plane all fastened up and as sleek as it could be. The plane still had a slight right roll which resulted in about an inch of each aileron being deflected and causing undue drag. Greg had planned on fairing over some small parts around the wheelpants and gear leg intersections. We had hotter than normal CHT's due to an 'experiment' with adding a ramp to one side of the cylinder heads at the entrance. This proved to actually make the majority of the air go over the cylinders at any angle of attack and out the outflow. I understand that with the ramp removed the CHT's are more uniform now. With these little improvements that Greg has done I imagine he'll pick up another 10 knots or so at least.

There had been the thought of testing some gap seals on the prototype to get some additional speed for free type of an improvement. I had also suggested a winglet design for cruise performance, looks, and the added stability for long cruise flights. If correctly designed they would slightly increase speed, increase range and climb rates, decrease takeoff roll, but I believe the looks are worth as much if not more than the performance gains.

If any of you know Greg or if he is part of the list, tell him that I'd be happy to make the journey out west to fly any of the customer planes on some of the first flights. They all are a little bit different and all have their own special needs as far as setting them up. Once you get things right though you get a "Lightning" fast airplane that is comfortable and stable. Hope you all enjoyed the read and any little improvements to the plane that you want to suggest I'll be sure to relay to Nick.
Brian Whittingham


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Rick



Joined: 24 Jul 2006
Posts: 113
Location: Colonial Beach, Virginia

PostPosted: Tue Aug 01, 2006 5:40 pm    Post subject: Pilot Report - Lightning Reply with quote

Brian,
Very good report!
Appreciate your comments.
Something I also have thought would(if nothing else) look good, would be
small winglets....so what do the rest of 'ya think??
As long as the weight is kept as light as possible, they should not hamper
rolling much either.
Look forward to some more flight reports!

Rick


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N1BZRich(at)AOL.COM
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PostPosted: Tue Aug 01, 2006 7:01 pm    Post subject: Pilot Report - Lightning Reply with quote

Hello again Brian,
Super job! Glad you took the time to provide0 your inputs and thoughts. I am sure all will enjoy your well written0 report. Since the list of pilots that have flown a Lightning is still0 relatively small (4), any information will be helpful to Lightning0 builders. Nick and I have flown the Prototype - Nick, Greg and you0 have flown Greg's airplane - and Nick has made the one flight on Earl's newest0 Lightning. The list will soon start to grow (Earl) and hopefully each0will0 add their own thoughts to the available flight data.
Nick and I were discussing some additional "clean0 up" ideas at OSH and I am currently looking for some material for flap gap0 seals. There used to be some clear tape available in the Pitts world that0 we used for aileron gap seals. I will get enough for my airplane0and0 the Prototype if I can still find it. If the flap gap seals0 work out, the next thing to try will be the same on the aileron gaps. 0The0 idea on the flap gap seals is purely for a speed increase (which0 I feel certain they will do) but until we try them, I am not sure how0 they will affect flap effectiveness. On the ailerons, the seals may add a0 little speed, but a bigger improvement may come from aileron effectiveness /0 lighter forces. We shall see.
As to winglets, the entire design (size, airfoil,0 shape, angle, etc) is critical to be effective. Most of the new high0 performance sailplanes have them. Done right, they will help, done wrong,0 they can detract in both performance and handling. Having said that,0 I also like their look. As a joke while I was building 31BZ, I cut a pair0 of winglets out of foam and taped them to the wing tips just to get a reaction0 out of the Shelbyville group. Some knew right away it was a joke, others0 said they looked great and thought I should glass them on. So I hope0 someone with the "aerodynamic smarts" to design some for the Lightning0will0 take on that task and make it happen.
Got back from OSH yesterday with one stop in Ohio0 for fuel and "pilot comfort". First leg block to block speed was 167.8 mph0 burning 5.9 gph. Second leg was 169.1 mph burning 6.3 gph. On this0 leg I had to climb to 13,500 (from 7,500) over the mountains of West Virginia to0 clear some buildups. The extra time to climb caused the extra fuel0 burn. Both going to and coming home from OSH, I flew over Lake0 Michigan, just as I used to do in my Bonanza. I am pretty confident in the0 airplane and Jabiru engine combination, but should something happen, the0 nice glide ratio makes the Lake Michigan "dead zone" much smaller or even non0 existent if you go high enough. I continue to be pleased with 31BZ's speed0 and economy. And it is even faster in the winter.
Blue Skies,
Buz


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Charles Heathco



Joined: 10 Jan 2006
Posts: 201

PostPosted: Wed Aug 02, 2006 5:11 am    Post subject: Pilot Report - Lightning Reply with quote

Hiya guys, re gap seals, When I had my cherokee I had a couple fellow0 drivers who aquired gap seals from Lopresti or Art Matson, Im not sure which.0 They were by STC for those planes, but they did improve performance. The tape0 Vans has for RV flap chafe protection might also work?? Charlie Heathco
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