4 engine V/STOL

That is great stuff i find it fascinating following this thredd, you are a very clever man.

Finally all together.
A short test run to about 3/4 power.

Even at this power it delivers well over 1lb thrust and as it weighs under 1lb it is firmly restrained by a large lump of lead on the floor.

With such a tiny wing (one square foot) and 4 motors it 'feels' ever so heavy.

With gales outside there is no chance of testing it so I have done some 'hand held' running.

With the 2200mAh flight battery the CofG is at 24%. Probably a bit far forward as flaps tend to move the CofP rearward as they descend.

With flaps up the elevator produces quite a significant nose up/down pitch and similarly the ailerons a roll force.
As the flaps go down the weight in hand reduces but with a nose down pitch. At about 20 degrees flap even full up elevator only just contains the nose down pitch.
At full flap the weight in hand is small but the nose down pitch is strong. The elevator has little effect although the ailerons remain effective.

Conclusion.
It should fly 'as is' (with a bit of tail ballast) but the maximum usable flap and thus the minimum flying speed will be determined by how far back the CofG can go and elevator authority.

A radical solution to both these problems springs to mind - independent prop wash over the tailplane.
This is sort of thing I had in mind.

In total they weigh 0.8oz which brings the CofG back to 30%, on the spar.

24" span and 6 props and motors!

Are you going to use a separate channel to control the rear motors or have you got some way of mixing & synchronizing them with the front ones or the flaps?

Hi
As soon as the weather is right (i.e. flat calm!) I intend to fly it without the rear motors and limit the amount of flap.

If the CofG position and elevator authority do prove inadequate as expected then I will fit them.

The simplest solution would be simply to connect their ESC to the flap channel. More flap = more elevator prop wash.

Connecting them to the main motors might be unwise. I doubt it is going to glide very well in any case but the extra prop turbulence right in front of the tailplane could be disastrous.

As they only take 2A flat out they will not have much effect on the battery.

With not much else to do I have started to paint it!

Much of the rest will probably be yellow.

It does fly - well sort of.
With such a high wing loading I elected to set about 15 degrees of flap and limited power for its maiden to keep the speed down. In hindsight I probably over did this.
No problem with the speed but roll control was.... er..... tricky, as this video shows.

As it was getting rather far away I shut down and landed as best I could but the tail boom was pulled out.
Conclusion
I fear the big wing end plates remove any lateral stability it may have had and coupled with big ailerons on a short span...........
On the plus side the counter rotating props seem to be doing their stuff and the CofG is not a mile out.

Now repaired so next time a bit less flap and a bit more power.
A gyro on those ailerons might not go amiss!

interesting flight

That looked like it was in a powered stall situation..... twitchy as hell but enough poke to get itself out of any trouble.
I'd move the COG forward a little & see if that settles it down a bit.
It's a noisy bu**er isn't it?

Pol.

Never again will I accuse *lectric motors of being silent - sounds like a hysteric flight of angry wasps!

Interesting flight though - I wonder if those big end plates are creating unwanted vortices with the prop wash. I'd be interested to see what difference it would make if you fitted them with about 30 degrees anhedral instead of what appears to be 90 degrees.

I think it just looked over sensitive .... maybe dial in about 80% expo on the ailerons & calm the blighter down?
I can't get used to this "not swearing" on the serious threads, but I don't want that Garrymodder bloke shouting at me.

Pol.

It was at nothing like full power but I was spending so much time trying to keep it under control I did not dare increase it or for that matter take off a bit of flap, both of which might have helped.

For the next attempt I think will remove the end plates altogether and substitute a simple wire skid to protect the out board props. The end plates are after all only likely to be really effective at significant flap angles which I am some way off using!

Tomorrow (actually now today!) the wind is supposed to drop to 3knots around lunchtime so I should be able to try again.
The wing end plates have been removed and wire tip skids added.

Hopefully this will give it a bit more roll stability or is that less roll instability?
Now I know it does not fly that fast I can use a touch less flap and a bit more power.
If I can keep it flying the last problem is the landing. There is every likelihood that with its high CofG and very short nose it will flip over forwards and damage the tail - again!
Maybe it should have the skid protruding out the front like an Avro 504!

Without the end plates the roll was a bit less sensitive so I did manage to get it to fly more or less under control.
The increased flap resulted in a nose up trim. As it was not flying that fast I decided to decrease the flap slightly rather than add nose down trim with possible stability issues.
On my Sky Sport TX the flap knob is on the right so you have to take your fingers off the aileron/elevator stick to move it. In my haste to I moved the knob the wrong way and added a bit more flap.
The result? Stall, wing drop, dive, stall, wing drop, dive......I was only 3 mistakes high!
With all this going on I was reluctant to let go of the stick and correct the flap which was what was really required.
The result was inevitable, a serious impact!

The fuselage virtually destroyed, 2 props broken, a motor torn out, the spar cracked and the wing tip crushed. The tail, boom and the flap sections were undamaged.
This flight did however convince me that it was never going to fly well enough to actually use the full flap movement. It would either be impossibly fast with no flap and impossibly unstable at full flap so a major rework seemed to be required.
Same configuration but only two motors and the flap reduced to only half the travel.
This would obviously mean vertical flight would no longer be possible but it should still posses a serious STOL capability although with undercarriage it would technically be just SL!
So first salvage the bits required.

A new wing.

With only 2 motors the electrics are much simpler and take up less space.

With the motor centre line raised just above the wing the props should be protected without any need for tip skids.