Dsegal
Posts: 1718
Joined: 10/20/2002
From: Philadelphia,
PA, USA
Status: offline
|
Ah spring!. Now it is time to flight-test all of those planes we built during that long, dark, Middle Atlantic states winter.
The first trip to the field did not go well. I opened the throttle and the plane trundled down the field and slowly drifted over to the right side. I had forgotten how sensitive is the alignment of steering on a tricycle plane due to the very short wheelbase compared to a taildragger. General consensus was that very thick grass and soft earth were a problem.
At home, things got worse. I went to the next larger wheel size all around (1/4" larger diameter) and rolled the model across the floor to get it going straight. Intending to be careful I decided to check the balance again. When I rubber-banded the wing on, to my horror, the plywood hook in the windshield gracefully pulled out of its former! If I had gotten airborne that would have been the end of the plane. I replaced the hook with epoxy and added a plywood backing plate behind the former with two screws through it. Days later I was still so worried that I did a static load test on the hook. The fuselage weighed just under two pounds. I hung it with string from the hook and from the aft fuselage to a ceiling hook. A 2 pound weight was attached under the belly giving a 2-G load. As this is not an F-16 I figured it would be adequate. Three hours later I removed the string and weights and prepared for another trip to the field.
Now it went straight down the runway but never approached takeoff velocity. It must be recognized that this is a belly-dragger- the nose is only 2" from the ground and the tail end is under 1" from the ground so the most of the belly and the stab are cruising through the grass blades. I assume it would have taken off from a hard runway. I then enlisted an expert launch-master who easily tossed it skyward. At 40% throttle it cruised nicely with full down elevator trim. Anything more and it climbed rapidly. Turns were smooth and slow fly-bys were stately. Feeling a little frisky, I gained altitude, dove and did a loop. The winds were now 90 degrees across the runway and this little boxcar did not like that at all. Landing was hard as it floats even on idle and it just wanted to head into the wind. I will avoid crosswinds in the future.
Back in the shop I inserted a 1/16" ply shim behind the motor mount to provide downthrust and reset the throttle for a lower idle. To raise the tail end of the fuselage the original, smaller, nosewheel went back on. Handlaunching is still necessary but the downthrust and elevator down trim make things smoother. Loops and stall turns are the only items in my repertoire. People get a kick out of seeing something fly past so slowly. This will be a great plane for keeping my pulse rate under control.
One problem: At half-throttle or more there is a tremendous buzzing coming from resonance in the wing. It destroys the image of a gentle flyer and I don't know what to do. I will check the prop for balance first.
< Message edited by Dsegal -- 5/16/2008 1:01:53 AM >
_____________________________
Dave Segal
|
Printable Version
All Forums >> RC Airplanes >> Vintage & Antique RC >> Live Wire II 
Live Wire II - 
