EAFerguson(at)AOL.COM
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 Posted: Sun Sep 10, 2006 10:01 am Post subject: N17EF data update |
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Listers:
I got the attached e-mail from Jeff Lachmund reminding me that I haven't posted any performance data on N17EF for some time. There isn't much to report, but here's the latest:
Grand Rapids had sent the wrong EFIS box, which got installed before Nick realized that it was the "Sport" version instead of the full Horizon I. As a result, my initial flights were without the EFIS. I did have the EIS installed, so I hade good engine instrumentation. However - no Nav capability except the mag compass and a clock. That lead to some minor excitement when the new mag compass decided not to point anywhere close to north. This happened at the southern end of a DR round robin, leaving me 35 miles south of Shelbyville. That's called VFR partial panel, or IFRR (I Follow rail Roads). The compass would not point between 030 and 330, period. I'll omit the details, bot I got back to Shelbyville OK. I took Buz's handheld GPS along on subsequent flights.
The EFIS finally arrived and got installed. Not having ever flown with one of these boxes, I'm learning. The capabilities are huge, but the device has to be set up, and we're in the process of doing that. I spent Friday and Saturday of this week in Shelbyville working on the chore list. At 35 hours, it was time for the first oil change and re-torque the heads. The spinner was out of balance, so we put a new one on and checked it. That took care of Friday, so I stayed over and worked Saturday. I was supposed to call Grand Rapids from the airplane Friday to go through some calibration stuff, but just didn't get to that. So Sat Ben helped with the setup procedure for the EIS and EFIS. They work together. Then I took a stab at the compass calibration procedure. It's called magnitometer calibration in the EFIS manual, and should take about 10 minutes. After an hour +, I finally finished, or so I thought.
With an accurate compass heading I could do a wind calc with the GPS track and GS and get accurate air speeds. We know the airspeed indicator is inaccurate at the low end of the speed range, it isn't even marked below 40K. Normally not important, but I'm certifying to the Light Sport 45K stall speed. So the plan for the Saturday flight was to get the airspeed calibration and do stalls. No luck, I still had an obvious compass error, maybe as much as 30 deg. Wasted flight, still no accurate stall speed. Rats! I'll talk to Grand Rapids about the calibration procedures tomorrow and find out what I did wrong.
The airplane now has 28 hours of the 40 required before I can fly it home. Because of the EFIS delay, I could hit the 40 hour mark before I have the required data for the Light Sport certification. Meanwhile there is a lot to do before it's fully operational. Mine is the first Light Sport Lightning, and Arion wants the performance data as much as I do.
Back to Jeff's questions:
My empty weight was 806 lbs. Since the weigh-in the only change has been the addition of the EFIS, We haven't updated the W&B for that, but the system is only about 2 lbs. As far as reducing the empty weight, they are working on that, and will probably find a few more pounds to trim. Check the Arion web site at http://www.arionaircraft.com for details and watch this list for announcements.
Regarding stability, I indicated slightly positive stability. Properly trimmed, it will fly straight and level until there is a disturbance, then there will be a change in pitch and or roll which may or may not damp out by itself. N17EF is still flying slightly out of rig, so accurate date isn't available. We're working on that. Another factor is fuel loading, since the airplane is light, it is very sensitive to fuel imbalance, which affects roll stability.This is clearly a sport aircraft, very responsive, but not highly stable.
Finally, Jeff asked about the ballistic parachute. No, I don't have (or want) one, and that adds significant weight.
Earl Ferguson
Atlanta
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Jeff's e-mail:
Hi again Earl from Australia,
I trust you don't mind just some questions I missed from the previous email.
Your mention the pitch and roll as 'slightly positive'. Can you spell out
what you mean. The empty weight finished up at 806. Do you think you could
have reduced this and where? Obviously this figure will increase with
instruments to be finalised etc. Have you installed the ballistic
Parachute? Have you had any further performace details to report since
Aug.26.
Regards Jeff Lachmund
Jindabyne, Australia
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