An edurance flight

[quorneng]

Quite some time ago now I set about modifying my Wing Dragon to see how long it could be made to fly for.
Eventually, although keeping to exactly the same dimensions and layout, I ended up with this all new build.

It is built almost entirely from 3mm Depron and weighs just 7oz ready to go less the battery.
It is designed around a 7.5oz 5000mAh 2s which completely fills the nose.

The target was a 'no lift' flight of 2 hours.
Yesterday was calm and rather misty so I had a go.
Launched at 9:56am
Landed at 12:01pm
2 Hours 5 minutes
Not bad for 40" pusher foamy!

The motor ran the entire time and there was definitely no lift.
As far as I can tell it was not at the LVC but I was about at the limit of my endurance and couldn't face carrying on any longer. I still have a stiff neck!

I think there are a few aerodynamic 'tweeks' possible to increase the duration further but such long flights are difficult and incredibly boring to do. I think I will have to use a much smaller battery and ballast.

For example a 36 minute flight from a 1000mAh battery but ballasted to the weight of a 5000mAh one would be the equivalent to a 3 hour duration.

We shall see!

[mclarkson]

Congratulations on the success of your project!

[quorneng]

The next step, a 1000mAh 'ballast' battery.

The same dimensions, weight and weight distribution as the 5000MAh.
The first task is to see how long it will fly with this (about 25 minutes) and then see if I can improve on it, with an ultimate target of 36 minutes.

[Don Sims]

Congrats on reaching your goal!

[quorneng]

Flew the Endurance again this afternoon with the 1000mAh ballast battery right down the LVC. It was not really the result I was expecting as it flew for no less than 38 minutes.

All things being equal that would mean the 5000mAh battery would give an absolute endurance of 5x38 = 190 minutes or just over 3 hours and that's before adopting any of the aerodynamic improvements I have in mind.
Perhaps I should be considering a 4 hour target!

Even with its slow speed it could still cover quite a distance.
Maybe a foamy cross channel flight?

[dgjessing]

Originally Posted by quorneng

Maybe a foamy cross channel flight?

That would be cool! You in a fast boat, flying the model overhead?

[quorneng]

It would not have to be a particularly fast boat as the Endurance cruises at about 10 mph. Any wind would be a far bigger factor!

[FlyWheel]

As light as it is, have you considered some H-E solar cells? You could stay up all day.

Posted via Mobile Device

[quorneng]

I had looked into the possibility of solar cells but anything powerful and light enough would cost upwards of 100 times that of the complete plane.

The other problem is that here in the UK strong sunlight tends to be as rare as calm weather!

[quorneng]

Fitted a slightly coarser pitch prop (8x4.3) instead of 8x3.8 hoping this would be a bit more efficient at the low cruising power.

So with the 1000mAh 'ballast' battery
Launch 15:11
Land 15:54
That 43 minutes or the equivalent of 3hours 35minutes with the full 5000mAh.
WOW!

The Endurance with the raked wing tips fitted.

If these work as I hope then 48 minutes (4 hours) really is a possibility.

[stuart]

4hours !!!!yikes

this will requie a few drinks,food,maybe a bathroom break. also a tv to glance at watching football[jk].

i really like reading your thread on this subject of endurance flights. may have to give it ago some time. longest flight i'v had so far is aroun 40 mins soaring the skimmer,and my neck was hurting is the only reason i came down. plus i wanted to get off the flight line while other buds were flying.but for the hr+ long flights i'd want a reclining beach chair with head cushion and drink holder. now that would be cool to try.

by the way,the reason for the fast boat on the cross channel fight is so you can hit a pub while the auto pilot gps gyro flys your plane at 10mph across the channel and you step outside to land it when she arrives.

[vonveska]

An interesting project. Congratulations on what you have achieved so far - and it's only beginning. Please keep us informed.

[mclarkson]

Originally Posted by stuart

4hours !!!!yikes

i'd want a reclining beach chair with head cushion and drink holder. D.

Chaise lounge and VR goggles.

[quorneng]

Calm and cold, very cold, this morning.
With the 1000mAh ballast battery on board launched at 8:52. Landed at 9:53.

The maths suggest that with the full 5000mAh the maximum duration is not 4 hours but 5!

Unless the battery is considerably under rated (unlikely) flying for 1 hour on 1000mAh means 1A and with a 2s that's just 7.5W and the radio and servos take some of that as well.
The Endurance weighs 14.5oz so it is using only 8.3W/lb

Low power flying in the extreme!

[stuart]

quorneng,

what are the VR goggles,sounds interesting. if they are for improving vision at altitude i would love a pair.

[ianfox]

Good effort mate!

[mcmoggy]

Great stuff Quorneng! Very interested in your progress and your intelligent approach to aerodynamic engineering.

[quorneng]

The Endurance has always flown with a slight off set to the ailerons. I put it down to a small aerodynamic discrepancy in the wing.

I just happened to hold the Endurance up to the light and noticed that the inner pair of wing ribs were not equally spaced from the fuselage centre line but they all appeared equally spaced out along the wing.
It was almost as if the wing was not in the middle........surely not!
Oh yes it is. About 5mm off set!!!
Although it doesn't seem to bother it much.
Centring the wing would be quite involved as the motor would have to be repositioned as well.
Simplest solution shorten the longer wing by cutting off the complete tip, removing 5mm from the centre section and gluing back together.

As the tips were only glued and taped originally no strength will be lost and perhaps not having to off set the ailerons will reduce the drag just a bit.

[mcmoggy]

Good intelligent thought process and solution Quorneng, hope the adverse aileron problem is solved. Have a McMoggypat on the back chap.

[quorneng]

Just a final update
With the wings now of exactly equal length I tested it today in cold but surprising choppy wind conditions.
It still needed a slight aileron off set so it looks like the wing does have a bit of an aerodynamic twist after all but not a rigorous test as the Endurance does not like any wind at all!