A battery wing?

[Simon Chaddock]

The Blue Wonder motors have a very distinct magnetic steps.

At a particular slow speed these magnetic steps exactly match the resonance frequency of the Depron structure and the sound is greatly amplified.

!

In fact it sounds like the motor bearings are disintegrating!

Fortunately the resonant frequency occurs at a speed well below flying power, but an interesting phenomenon nevertheless.

[Simon Chaddock]

It flies!

As it felt so heavy and not being easy to hand launch I set the elevator neutral slightly up on the grounds it was better to climb than dive into the ground.

I need not have bothered as climb it did to almost vertical.!

Full down trim just about got it under control and it started to fly quite nicely.

Adequate power even at part throttle (it only has 6V to start with), bags of aileron authority and a nice flat glide.

A few circuits and a nice gentle landing into wind with a final ground speed of almost nothing.

Encouraged I tweaked the elevator horn down a bit and had another go (with an almost inevitable result). You never seem to learn!

This occurred as I was coming into land after an otherwise successful flight.

A bit too slow on approach, wing drop, slow recovery (those heavy batteries in the wing!) other wing drops, slow recovery, full power to get out of trouble, too late, wing tip touches. Classic stuff.

In hindsight I would have done better just to let it gently crash as when the nose broke the prop almost chopped right through the top of the spar, it even nicked the battery shrink wrap underneath. On the plus side the fragile nose probably prevented any other structural damage.

It will all mend easily enough with a slightly longer (and stronger) nose to move the CofG a touch further forward and hopefully with a video of the almost zero speed landing. 

[Tim Mackey]

Oh bad luck Simon - but a success in many other ways

[Biggles' Elder Brother - Moderator]

At least its two steps forward and only one back! It could be worse - it could be the other way round!

 

Well done - can't wait for the video of a future flight!

 

BEB

[Simon Chaddock]

The new,  longer nose. It could now take a 9" folder if required.

The repaired spar.

Mostly relying on glue but it still can take the wing tip test with ease. (lift it by the wing tips = 4g flight load)

 

[Simon Chaddock]

Here it is in its MkII form.

Apart from the longer nose the other changes are quite small. The tail plane and fin leading edges have been remodelled (mainly for appearance rather than aerodynamics) and the elevator neutral position adjusted.

It flies well enough but I am still not entirely happy with it. Difficult to pin point but its just not 'nice'.

I suspect its the harmony of the controls, the ailerons are too powerful and the elevator weak but then maybe I am just being picky.

A bigger elevator is the next mod.

[Paddy Fidling]

Looking good simon, can't wait for a flying video!

 

Paddy

Edited By Paddy Fidling on 16/06/2010 20:55:19

[Simon Chaddock]

This is a terrible video of the final part of the last flight this evening.

1. The Key Fob cam vibrated on its mounting.

2. The prop blade folded right in view.

3. Note the lateral oscillations (it does this by itself).

However the landing is commendably short 

 

I need to get its flight characteristics sorted and probably mount the cam looking backwards.

 

[Simon Chaddock]

I judged the video confirmed that the Battery Wing is suffering from both directional and longitudinal stability.

The normal remedy is more fin and tail plane area, so on to the MkIII version.

Simple and quick. The elevator & fin are both about 40% bigger and the fixed tailplane about 20%.

This resulted in a significant improvement, still not perfect but I was confident enough to undertake mild aerobatics - loops, rolls & inverted flight (just!).

However by far the biggest challenge is actually getting down, the approach has to be long and low to stand any chance of coming to rest within the field's boundary although the landing itself is a non event, just a gentle flop onto the grass.

After 7 flights (20 mins total) I tried a really low approach and lost sight of (and control) behind some trees and broke the nose again but as before no other damage.

Just as well Depron glues well!

[Simon Chaddock]

Hopefully the last 'adjustment' - unless of course I crash it again!

Balsa this time not Depron.

A much more conventional approach. 1/8" motor bearers.

Two formers at the nose to pick up the motor & completed with 3/32" balsa planking faired from circular at the motor to rectangular where it joins the spar.

A bit heavier than Depron (it needs the nose weight) but a great deal more rigid. 

Apart from visibility the paint also waterproofs the bare wood.

Now to try again. 

 

[Simon Chaddock]

A rather better video of a short flight with the Key Fob cam mounted on the starboard wing but still within the prop arc.

It was rather turbulent and the Battery Wing is certainly not the most stable of planes but the landing is very short.

In an earlier flight I was amazed to find it is stable inverted in fact it was a second or two before I realised it was still flying upside-down with no stick input required.

Edited By Simon Chaddock on 21/06/2010 23:47:24

[Simon Chaddock]

The above video was shot with nearly 1/2 oz of lead shot in the nose. It did not improve the flight characteristic that much and certainly took the edge of the climb.

It did display quite a big trim change power on/off so some down thrust has been added by the simple method of cutting the nose off, sanding the edges and gluing it back on!

Next is to modify the fin keeping the same area but moved a bit further back.

Edited By Simon Chaddock on 22/06/2010 22:45:54

[Simon Chaddock]

A further attempt to improve the directional stability - add the extra area to the TE of the fin rather than to its LE as I did previously.

An unusual fin cut out to accommodate the 'barn door' elevator.

[Simon Chaddock]

At last its beginning to fly reasonably.

A short rear facing video of a launch, climb, circuit and landing in absolutely still conditions.

This view shows that the tail flexes quite bit even in gentle manoeuvres.

The landing sounds much more violent than it is. With full up elevator at touchdown It is really just a gentle flop.

[Simon Chaddock]

The cold and snow got me thinking "what needs doing on my various planes?"

 

Although it flies reasonable well I felt the Battery Wing needed attention as the controls were poorly harmonised. The ailerons are too powerful, the elevator rather weak along with poor directional stability. Not much really.

So first reduce the ailerons by 60% and restore the trailing edge.

Harder was extracting the aileron servos and disconnecting them from the radio so they could be repositioned further outboard.

Next will be new tail feathers set further back.

Edited By Simon Chaddock on 04/12/2010 23:22:35

[Simon Chaddock]

The directional stability of the Battery Wing was always marginal so although the new fin is of a similar area it has a much higher aspect ratio.

The forward part of the lower fin is yet to be added.

The tail plane area is also about the same but with a more sophisticated two part elevator.

All the surfaces are simple 3mm sheet Depron with balsa stiffening.

The leading edges have a basic round profile but the trailing edges are tapered down to 0.5mm.

Hopefully the Battery Wing's flying characteristics will end up 'sorted' so I can finally find out how the A123 cells perform.

[Simon Chaddock]

With the mods complete it is now in Mk V form

Hopefully it will now fly well enough to explore the performance of the A123 cells. It should have a cruise endurance of at least 30 minutes.

 

Now if I made one a bit bigger with 15 cells all along the wing in a 3s(9v)5p(5000mAh)  set up it would fly for....er.....quite along time.

[Simon Chaddock]

The second test flight with the new tail feathers.

It was only when I saw the video that I realised the joint between the elevator halves had cracked. Seemed to manage ok on one but the tail plane did deflect and twist a bit pulling full up entering a loop.

It is still not a brilliant flier but it does ok on just 6V.

[Stephen Jones]

Hi Simon ,

Its been awhile but i have come across that article in Radio Modeller where Alfi Polor explains the technical breakthrough in electric flight by making a battery foam wing . And shows a test rig of polystyrene ceiling ties aluminium foil to make a working battery .

I removed the page and throw the rest of the mag out so i do not know what year it was but on the other side of the page it does mention that the Nuremberg Toy and Hobby Fair is in its 42nd year .

Not sure if i can scan the page to show you do to copyright .

[Martin Whybrow]

Posted by Stephen Jones on 25/06/2012 21:19:54:

Hi Simon ,

Its been awhile but i have come across that article in Radio Modeller where Alfi Polor explains the technical breakthrough in electric flight by making a battery foam wing . And shows a test rig of polystyrene ceiling ties aluminium foil to make a working battery .

I removed the page and throw the rest of the mag out so i do not know what year it was but on the other side of the page it does mention that the Nuremberg Toy and Hobby Fair is in its 42nd year .

Not sure if i can scan the page to show you do to copyright .

Can't help you on the year, but I would guess it was the April edition

[Former Member]

[This posting has been removed]

[DH 82A]

The lipo was invented by Rolf A. Lipo, and was named after him, like the Biro pen was named after it's inventor.

[Former Member]

[This posting has been removed]

[Stephen Jones]

Dear Mod ,

Can i show a scan of this article ?