|Posted: Sun Jan 14, 2007 7:46 am Post subject: Lightning-List Digest: 5 Msgs - 01/13/07
Buz is right, I haven't been posting results like I should, so here's an update.
N17EF now has almost 60 hours total. I brought it home from Shelbyville in Nov, left there at almost exactly 40 hours. I'm flying under Light Sport rules, so I don't have the gear clean-up stuff, just bare wheels hanging out there. I added vortex generators to get the required stall speed. Your results may be different, but I was getting about 47K clean stalls, 2K over the required for LSA. The VGs solved that by taking off 3 to 4 K. VGs do change the stall characteristics with a sharp nose drop at stall. I suggest future LSAs using them start further out from the fuselage. Mine start at 2" - 3" from the wing gap.
Currently I'm doing performance testing, speed, altitude, fuel consumption, etc. I have the ground adjustable prop, and am playing with pitch for max allowable speed (120K, etc). This also affects fuel consumption, but with bare wheels, I won't come close to Buz's performance numbers.
Currently I'm seeing about 110K true at 2750 RPM. That varies with altitude and OAT of course, but I'm bumping the prop pitch up a little. At that power setting, fuel burn is about 5 GPH which should go down some at higher prop pitch. Fuel burn rate goes up quickly as you add power, but no good data on that yet.
I added the Grand Rapids fuel flow system, which has to be calibrated. It's getting close, but is set by trial and error. So for now its climb up, switch tanks set power and cruise, then land and refuel. Calculate fuel from the results. Its time consuming. For those who do this, you will find that the fuel level read outs change by about 0.2 gal per tank after TO due to the change in attitude, so you can't just use the gauge read outs.. That makes climb out fuel burn more difficult. Naturally the line crews also vary some in refilling. All this makes good data tedious and time consuming.
But I digress. For those considering a Lightning, it's a pleasure to fly, very responsive, control forces are light. Seating is very comfortable, even though I don't have an interior in yet. Visibility is outstanding. Stability, which has been discussed here before, is neutral. In rough air, it requires constant attention. Smooth air is much better.
Speaking of rough air, I've encountered some moderate turbulence. and it isn't a problem except for the attention required.
I have an engine item which needs discussing. In cold weather starting isn't easy, and the battery goes down pretty quickly. My hanger isn't heated, so starts have become somewhat of a problem. My solution is to put an electric heater on a timer and aim it at the engine compartment. Nick had some suggestions for cold starts which helped. Close the throttle and pull the prop through 6 to 8 blades. There is no accelerator pump on the carb. Start with the throttle closed, which helps pull fuel into the intakes. I'd like to hear from other Jabiru 3300 owners on how they are doing cold wx starts.
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