HGRAFF(at)aol.com
Guest
|
 Posted: Fri Sep 04, 2009 4:18 pm Post subject: Third Impressions |
 |
|
Finally, after a couple of (2 hour) trips to the airport, the Field Repair/modifications were complete to test fly the Mark IIIc. There had been three problems, heavy left wing, absurd airspeed indications, staying below RPM redline.
1. The heavy left wing was solved with a trim tab under the right wing aileron, in size to the precise specifications of an off-line helper. (18" x 4" aluminum, bent in the middle to lift edge by 1/2").
This solution hit square on the head, completely correcting the left roll tendency to the point of being able to remove my grip while the A/C keeps trucking on with wings level. The fix corrected the left roll, likely caused by the clockwise rotation of engine.
After about 3 seconds of hands free operation, I need to take over control again, because of a slight pitch down tendency with zero trim. Going to the first trim notch results in a slight nose up tendency. I stayed with the zero trim. (There is a good suggestion to fix this, but a Winter Job).
To make the flag fly straight, I need to put in a bit of left rudder. Without this rudder the flag flies approximately 10 degrees off center. The rudder input did not seem to have much effect on the lateral stability, confirming the discussions about inability of keeping the Kolb level with rudder alone.
2. The absurd airspeed indications (almost one airspeed for all occasions) were solved by two steps. First relocation of the pitot/static from the top of the fairing the bottom, according to a second off-line assist from a good soul, who supplied measurements and advise. While having the unit out, I noticed that this "semi-professional" beautiful piece of stainless steel art, had the Static holes not only staggered, but facing about 45 degrees down (as when mounted above). Well, trying to drill new holes properly in the field was futile. I had to take the thing home, where, with a drill press, I promptly broke/dulled three new 1/16 drill bits. But, in the end I won properly over this dastardly piece of stainless steel.
With the pitot remounted to the bottom, I took off and marveled at the fantastic airspeed of zero and flew the entire circuit this way. With markings on the tubings, I could have sworn in court the dang lines were connected correctly, but of course, they were reversed.
With that corrected, the next flight showed delightful airspeeds. Our little 65 HP Hirth engine, easily shows 60 MPH in cruise, when pushed at near full power even 70 MPH. I did not do any GPS or stall tests, because of only 20% fuel in the tanks, there was this awful urge to walk the ground.
3. Staying below Redline This was to be a simple fix to reset the pitch on the prop. But after walking up to the prop and staring at the cap-bolts, that need a special 6 mm tool with 3/8 drive to utilize the torque wrench, it was a job for another day. On that other day, re-pitching went well. In two steps, Pitch was increased from 8.75 degrees to 10.50 degrees, reducing static RPM from 6,400 to 5,900. Now, climb out can be made at full power. In cruise, as usual, you must still watch RPM. Anyway, this is happy times now.
General impressions: Feeling a lot more relaxed flying this butterfly, I mean Kolb. Landings are fine. I noticed what may give rise to discussion. The aircraft feels fine and comfortable up to 60 MPH, but when pushed to 70 it seems to become "squirrely". I had this feeling when pushed in cruise, as well as on descent to land when in a hurry to get down. Anybody that has owned a motorbike will know, each bike has a comfort speed limit. This came to mind when at high speed (Haha!) every little air burble was more upsetting. I slow down, and things feel "normal". Now I've seen Kolb movies, with bigger engines, showing 90 MPH with seemingly great steadiness. Perhaps all I need is more acclimation?
Herb
Mark IIIc, 246KT Grand total of 2.1 hrs
[quote][b]
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
