Another go at 2 hours!

[quorneng]

In 2009 I flew this heavily modified Wing Dragon non stop for 1hr 36 mins.
   
Using the same wing and battery but with a low kV motor and big prop this was intended to go for 2 hours.
   
But it didn't!
A less than ideal prop/motor combination coupled with some serious stability issues prevented any serious endurance attempt.
Other builds took priority but now there is time for a complete rethink.
The wing, boom and tail will be used but in a pusher configuration with a smaller motor and prop.
   
The drive line under test.
   
The 1500kV Blue Wonder on a 2S with a 7x6 draws just 6A at full power. At 2.5A (0.5C) it still produces a good 2oz thrust.
The new '2 hour' plane should weigh just under 16oz so provided it has a lift/drag ratio of 8:1 or better is should manage 2 hours.

I do not claim this will be any sort of record but I got tired of looking at a complete, flyable but 'unsuccessful' plane simply hanging on the wall!

[quorneng]

Completed
   
The battery occupies the complete nose section.
   
It weighs 14.2oz of which the battery makes up 52%.
So far only test flights.
Flies pretty slowly but build up a bit of speed it will loop and roll power off.

[Richard]

2 hours will be a long time at the sticks. Will you be seated when you go for it?

[quorneng]

I did the 1hr 36min flight standing all right but got a really stiff neck!

I plan to try 2 hours on a warm sunny day, sitting in a deckchair, with a floppy hat and a long drink!

A video of a short test flight in far from ideal conditions.



I need to do some more testing with different props to determine the most efficient set up.

[quorneng]

This video shows the 'Endurance' rather better as it was flown low specifically for the video. Frosty Sunday morning hence the church bells!



As indicated the launch is at just 1C and it gets down to 0.5C (2.5A) later in the flight. It is even modestly aerobatic.
At the 2 hour duration power setting it is very close to the stall which makes it rather 'twitchy' for low flying.

[Richard]

It flys well.

Maybe you could try a larger a battery to reach the 2hr duration?

I wonder if you could set up your TX with a 'cruse' mode... Like you would flick some switch would would apply a little rudder/elevator just to keep it the plane circling, then you could fly it up wind, flick the switch and wait for it to work its way back to you.

[quorneng]

In the video it is flying with a 5000mAh 2S battery so at 0.5C it should just about last 2 hours.

I was flying low for the camera but once trimmed at a reasonable height it will fly for quite long periods without much input which is important as over 2 hours the servo draw can become significant.

[Alan H]

(17-02-2012 23:54)quorneng Wrote:  In the video it is flying with a 5000mAh 2S battery so at 0.5C it should just about last 2 hours.

Bear in mind that LiPo capacity deteriorates with cell age and number of cycles used. Also this cycle aging is worse if you deep discharge as you are proposing.

[quorneng]

The current draw is very small so for a normal 20 minute flight only 15% of the capacity is used so the battery has a pretty easy life.
Deep discharge cycling should not be too much of a problem as I sincerely hope I will only have to do a full 2 hour flight just once!