Originally Posted by stingeragents
Flight report. Well had to build a small handle on bottom of plane as it was too wide to hand launch as is. Throttled up to about 3/4 and let her rip. Had a slow but straight climb out. Next to no aileron control until it picked up speed. Running elevons only at the moment with 100% dual rate and 120% epa. As it slowly picked up speed I gained a bit more aileron authority. First thing to my mind as I let go of the sticks. It needed 0 trim and it was perfectly stable. Felt like flying a trainer plane. It was going rather slow at 1/2 throttle, maybe 30-40 tops, so as I made the first circuit and turned back around I advanced up to full throttle. Didn't sound as if the fan was spinning any faster. Held it at wot for about 5 secs and then the motor cuts out, crap. Made a quick left turn and pointed the nose down to maintain momentum. Glided it to the ground with only a soft thud. My hand launcher was only thing that dented a tad. So as I walk over to the plane and pick it up to check for damage, I give it a bit of throttle and it works. Hrmmm. It wouldn't turn back on in the air. I start thinking low voltage perhaps, but when I got home to charge up the 4s 2200 pack, it was at 16v still and only put back in 250mah, so that can't be it. Only thing I can think is the battery may be bad. Its had a crash before and is a bit dented in the front. Balances fine up to the correct voltage so not real sure on that. It is the detrum 70mm fan/motor/esc combo from hobbypartz which was working fine in another plane. Any takers?
Edit: I have no watt meter unfortunately to test the battery with a load on the ground. Went back and redid esc programming just to make sure it wasnt messed up. Well i guess my next step is to fly it with a different battery. If that works guess ill toss the other one
I would think it might be your esc started to over heat and shut down. You might want to install an external ubec to be safe. Could solve your problem by removing some heat. Also check all your solder connections. I would do a full test on the ground. Get two hair dryers and blow cool air into the ducks while running the motor and see if the motor cuts out on you again. Move your sticks on all your control surfaces along with different throttle ranges as if you are flying. Do you have the esc in the airflow for cooling? How long was your flight? Was your battery warm or cool to the touch upon landing? Did you check to see if the esc was hot?
Try your new battery pack on the ground as suggested above. You should also be able to use a bigger battery pack. Another reason to get a watt meter so you know what size (mah) and "C" rating battery pack will be your best fit for performance.
If you plan to build any more planes I strongly suggest you get a watt meter. Just because the system worked fine in one plane does not mean it will in another. You could be pulling more amps as the air needs to pull further through the ducting.
Jet looks good! Like to see the final paint job pictures. Have you painted her yet or are you test flying before painting?