Electric Indoor Control Line

[quorneng]

Again a long time ago I reasoned the only way I could fly any time I wanted was indoors.
Unfortunately I did not live in a baronial hall so it had to done in a normal room.
The only acceptable power would be electric.
The obvious solution was simple 'round the pole' but as the motor required two wires to carry the current why not make them elevator control lines as well.
Obviously the centre pole is a bit more complicated but I found small light planes could be satisfactorily flown on lines as short as 5'.
In fact with both power & elevator control the whole process was so smooth that very complex and delicate models stood a chance of surviving for some time.
A scale Fokker Triplane at 16" span looked an ideal candidate.
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In this case it was not just scale shape but built to scale as well.
This is the only picture I have of it under construction.
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The fuselage is made up of 1mm round balsa to simulate the steel tube of the original. The wing structure is almost perfect scale but in 1/32 balsa.
The "slot car" motor is geared down 2.7:1 to drive a scale diam and pitch carved balsa prop. An Oberursal rotary goes round with it in a spun ally cowl.
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The U/C & tail skid are correctly sprung using elastic cotton as the bungee cord and the elevators are scale cabled to the joystick. The control line bell crank simply moves the joystick.
It weighs just 2.25oz and flew very well but is now in 'retirement' as it is 40 years old, however this ground run was taken quite recently.
[video=youtube]4PIV0f6TZOE[/video]
Electric Control planes live long!

[plummet]

Beautiful. Thanks.

More?

Plummet

[Tony Smith]

Very, very nice.....

You should compare notes with Brian, he has flown electric C/L, his specialty is 'light aerobatics '....

[quorneng]

I actually built quite a few, both scale and experimental, but of course not all survived.
I experimented with 'carrier landing' using an elastic arrestor wire. This had the advantage that with judicious use of the throttle you could control how the plane was pulled back to the starting point so that it dropped the wire and you could take off again.
For a school demonstration I built this Fairey Gannet from the KK rubber scale series plans although I cheated a bit a broadened the wing chord to increase the area.
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I found that 3 pole armature motors create a highly pulsed current which means that motors in series conflict with each other.
This has its 4 engines in a cross connected 2s2p layout to help even out the pulses.
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With low revving direct drive it is almost silent in flight. The long stroke U/C uses retractable ball point pen springs. It does have to be stored carefully as each motor weighs more that the entire airframe!
I added a third electric line for this to work the full span flaps and rear door.
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It carried and could drop in flight a full size tissue and balsa house brick!
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The last (to date!) is the elegant Martin Baker MB5.
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Built almost entirely in 1/32 sheet it is a true monocoque with all the stresses carried by the skin. Even the wing has no spar as such.
Each of the scale props are driven by a separate motor.
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A fully detailed cockpit with a home moulded acetate canopy.
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A bit bigger and heavier than the others (22" span 4.5oz) it flies very nicely but you have to be sooooooo careful when landing to keep all those prop blades (they are only balsa) clear of the ground.
Surprisingly noisy (the hollow structure acts as a sounding board) it sounds more like a turboprop.
A short ground run.
[video=youtube]kOTJZ3grd8I[/video]
I even built a couple of control line helicopters but never did get them to hover properly!

[Richard]

Quote:Originally posted by Tony Smith

You should compare notes with Brian, he has flown electric C/L, his specialty is 'light aerobatics '....

The memory always brings a smile to my face