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Keil Kraft Ladybird

Electric Motors

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Bernard Chiswell14/06/2015 16:45:31
24 forum posts

I have one of these kits but no Mills .75. So I thought I would convert to electric, but what size motor and outrunner or otherwise? Help please. Thanks.

Percy Verance14/06/2015 17:13:30
8108 forum posts
155 photos

I'm no electric expert Bernard, but you won't need a great deal of power. Something like a 100 to 150 watts and 1000 to 1200kv I'd have thought.

The Ladybird isn't a looping or rolling type model, so in the region of 80 watts per pound of model weight ought to do nicely. Someone who knows the electric scene far better than I will be along soon Bernard.........

GONZO14/06/2015 18:43:35
1334 forum posts
14 photos

The Mills 1.3 puts out 85 to 90 Watts @ 10,500 rpm approx. The Mills .75 puts out 41 to 43 Watts @ 10,800 rpm approx. But, you would not normally opperate them at these rpm, 8,000 rpm would be about normal. The .75 would use a 7 x 4-5 and the 1.3 would use a 9 x4 or 10 x 3.5-4. The model was mainly for free flight using the Mills .75. For electric RC give yourself a bit of headroom and go for say 100Watts or just over for a plane calling for a Mills .75 and 130Watts - 150Watts(max) for a plane calling for a Mills 1.3. Select a motor that will give these powers at similar rpm using an 8" prop for the Mills .75 design and 9" to 10" for the Mills 1.3. Over powering old free flight designs can give undesirable handling. You may also want to look at the dihedral angle, which was generally OK for free flight but is excessive for RC. A guide I've read about calls for 1" per foot per half span plus 1" ie 36" total span give 18" half span. Thus 1.5" plus 1" under each wing tip, this for RET RC.


GONZO14/06/2015 19:37:15
1334 forum posts
14 photos

This downloadable plan is for an updated Laybird with RC mods **LINK**

Tim Hooper14/06/2015 19:51:12
2866 forum posts
2363 photos

My own Ladybird has had two power systems;

Mega 1615/6 turning a 9x6 prop, on 2S1300 lip-po. Grossly over-powered.

Currently converted to free-flight;

Turnigy 1811 2000 kv motor, 6x4 prop. 2S 1300 li-po. Measured at 65 watts. Ample.


Percy Verance14/06/2015 20:02:43
8108 forum posts
155 photos

There's also (I think) a kit available from Replikit............

Paul Jefferies14/06/2015 23:01:34
254 forum posts
39 photos

This amounts to a confession!

I built a Ladybird back in the day (early 60s/my early teens). It flew very well with my trusty Mills.75 (which I still have)............ until one wing fell off! The box in the fuselage into which the wings plug, had become slightly cracked in a previous arrival causing the wings to become a bit loose. I wasn't able to properly repair it there and then but I had cycled for miles to the flying site and didn't want to stop flying so I wedged one wing in with some grass! (you don't need to say anything) The wing seemed reasonably secure so I fired up the Mills once more and the Ladybird soared back up into the wide blue yonder........ until the starboard wing fell off.  I can still see my most treasured posession spiralling down and hear the sickening crunch as it disintegrated on impact.

So the moral of the story is firstly....... If your wing box becomes damaged, don't repair it with grassfibre and more seriously, I suggest winding some heavy thread round the wing box before you fit it so that it cannot split when the wing takes a knock.


Edited By Paul Jefferies on 14/06/2015 23:02:54

Edited By Paul Jefferies on 14/06/2015 23:07:39

Bernard Chiswell15/06/2015 22:22:52
24 forum posts

Thank you all you great people for the answers to my quetions, much appreciated.

paul snaith26/07/2019 12:19:04
17 forum posts

Sorry im a bit late in joining the thread,

However , I too had one back in the day ,

Never got round to flying it ,

So now I'm older and richer !

I've acquired a kit on fleabay, and am going to re live my youth !

Just wondering if anyone has done a 4 channel electric conversion?

I'm no stranger to balsa dust ,but I would be grateful fo any advice or tips ,

Many thanks


Denis Watkins26/07/2019 14:27:42
3994 forum posts
73 photos

Electric details on this same site


Tim Flyer26/07/2019 18:45:34
1147 forum posts
220 photos

Sorry to hear that Paul . I must say that does make a really amusing story which you relate really well , definitely one for the tea huts. The idea of cycling a long way to fly and having to get the plain in the air no matter what also shows great youthful enthusiasm that we all had and often still have !!😉I also like your grassfibre pun. Must admit some of my planes have had a bit of grassfiber in after I have repaired the cowl with glue and noticed some errant grass inside.

paul d26/07/2019 19:15:00
85 forum posts
5 photos

"Grassfibre"! priceless...

Tom Sharp 226/07/2019 19:28:07
3593 forum posts
19 photos

I built a KK Ladybird around 1950. I remember you had to mold the cowl from a flat piece of ply. I made a pigs ear of this and though it flew alright it looked a total mess.

This total inaptitude in my building technique continued throughout my modeling career and was only rectified by the introduction of ARTF.

Edited By Tom Sharp 2 on 26/07/2019 19:29:50

paul snaith27/07/2019 08:22:03
17 forum posts

Thanks for the link Denis

J D 827/07/2019 09:05:39
1340 forum posts
78 photos

You are right about the cowl Tom, mine ended up more hexagonal than round. Flew on DC .75 merlin.


Capt Kremen27/07/2019 09:26:39
323 forum posts
100 photos

My recollection was that the cowl was formed using 1/32nd balsa sheet, soaked and rolled in two layers around a traditional 'old style' glass milk bottle. There is a sketch on the original plan illustrating this. Also, mine ended up with lots of down thrust which rather spoilt the would be 'D.H.Beaver' sports scale look. It flew superbly though and mine went AWOL for a few days until a kindly Forrest ranger knocked on a 8 year old's front door to reunite me with it!

J D 827/07/2019 15:42:47
1340 forum posts
78 photos

I grew up on a dairy farm so when I asked my parents for a milk bottle there were none to be had. Did not think to ask for another type that would do.blush

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