woensdag 13 juli 2011

Graupner Bellanca second flight

This time I took the TowerPro 40A ESC that already proved itself to work on 2 cell lipo's (get it now since that price is increasing really fast now).

Since the maiden finished so quickly I was very eager to get it flying. I went to my flying spot and took off, again using flaps. Not at all much wind this time and strange enough it wouldn't get off before I ran out of runway... It took me some runs the realize that ESC was still on very soft throttle mode from use in helicopters. No time to fix that (since I don't know the beeps and didn't have a manual with me), just found myself a longer runway :).

Again very smooth handling in the air. I still used the advised 50% expo on all channels. For the ailerons I quickly wanted a bit more responsive controls so shut that off quickly. Like on the maiden I only noticed my flaps were still on once I started banking for the first turn. Neutralized flaps and really got it flying well this time.

I stayed up now. I just didn't want to loose it. Turned out to be the better choice. In mid flight one of the wings suddenly dropped out of the sky getting the plane in a very steep and dangerous spin. Got it out just in time.

On another turn it also slided and got close to a spin very soon. If you want to fly it properly you need to be smooth on the controls.

I was well after 4 minutes thinking what could have caused that dangerous wing drop! But I needed to come in for landing since I didn't properly test the motor consumption yet. I got to the pavement preparing to land, getting slower and slower... until just above the street that wing drop got me again. One wingtip smashed right into the street making it flip over... well I landed it.

Got to the crime scene fast to check damage. Again one of the nylon bolts broke and one of the struts of the wings was off. Only one wingtip had more damage this time. The one that hit the street first was smashed a bit. Still an easy fix though.

And now I need to find out what caused these nasty wing drops. Don't think it's just low speed and stalling because it looks way to aggressive to me and why the hell is it only a single wing while I'm flying straight!?

It might be the combination of a cheap ESC, providing only 1.5A through it's integrated BEC and the 4x HXT900 servo's. I recently discovered on rcgroups (search for it) that one of these servo's can draw just over 1A when under high load!

Another possible cause is the pushrods for the ailerons. If kept too long (you need to cut them once in place) they can hook up on the wing where the servo arm gets out.

Update: I'm going with this 30A ESC, it has a 3A built in BEC so that should do (and much easier on the connections, and much lighter as well): http://www.giantcod.co.uk/speed-controller-p-405437.html. Good flying weather today. Hope to get to some airtime! => check this blog post.

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