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The Ohmen

My first electric powered aerobatic model

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Peter Miller10/07/2020 08:54:46
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When you get that far it does sensational Lomecevaks! But don't worry it is NOT twitchy on low rates or high rates.

Low pass Pete10/07/2020 09:00:24
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Posted by David Clark 18 on 10/07/2020 08:50:32:

Thanks for the reply and your suggestions. They are all of interest, is the Renaissance designed for electric, I have a number of 3s 2200 and 3700 batteries which made the ohmen very attractive.

No Renaissance was originally designed for IC but a lot have gone electric. Lindsay Todd the designer also did a biplane named Skywriter for electric, mine was converted to IC. Ballerina was designed for IC but a lot were converted to Electric. There are build forums on both of these as they were subjects of RCM&E Mass builds in 2016 and 17. You can get plans and pre cut parts from SARIK on all these. 20180512_080839.jpg

David Clark 1810/07/2020 09:16:51
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Thanks again Pete. I'll have a good look at all those and check them out on the forums. They are all names that I recognise, I guess that's because they are all good designs that have stood the test. I just have to bite the bullet and make a choice.

Peter Miller10/07/2020 10:48:14
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I did convert my own originl Ballerina to electric. 4-Max 3541 1070 motor. I felt that it could have done with a fraction more power but then I really like to throw my models all over the sky.

David Clark 1810/07/2020 10:59:14
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Hi Peter. I'm still at the stage where a nice level circuit and a reasonably low pass are an achievement. I'm not looking for an aerobatic model just a scale like plane that will get me into low wing flying but at a future time will give me the opportunity to develop.

Peter Miller10/07/2020 11:02:50
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Ballerina will do that. I used to spend the last flight of the day just doing touch and goes for which it was the best of my stable

David Clark 1810/07/2020 11:07:52
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Would you say that Ballerina is more suited to what I want than Ohmen.

Peter Miller10/07/2020 11:12:55
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I would say probably yes. Being a bit bigger and also a little tougher as it was designed to use a .40 four stroke.

Being a bit bigger it is also easier to see at any distance.

David Clark 1810/07/2020 11:17:56
11 forum posts

Thanks for your help. I'll have a good look at the Ballerina forum then get the plan. I like to do it the hard way, cutting everything myself. Thanks also for the continued designs which all seem eminently practical both to build and fly.

Peter Miller10/07/2020 11:34:03
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Doing ones own cutting saves a small fortune.

Piers Bowlan10/07/2020 11:41:39
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Posted by Peter Miller on 10/07/2020 10:48:14:

I did convert my own originl Ballerina to electric. 4-Max 3541 1070 motor. I felt that it could have done with a fraction more power but then I really like to throw my models all over the sky.

4-Max recommend that motor here with a 3s 3300mAh LiPo, which power-wise is a little conservative for a 4.25Lb model perhaps. Presumably that is what you used Peter and fine for stooging about and a gentle flight performance. Fit a 4s LiPo battery in the same model and prop it so as not to exceed the 33A continuous (the motor is rated for) and the model could be transformed performance-wise. One advantage of electric flight is that it can be so flexible. Perhaps even better would be to use a similar sized motor with a slightly lower Kv (750kv?) on a 4s LiPo and not have to use a smaller prop to keep the amps under control - more efficient and better for aeros. 

Perhaps one like this? Motor 6mm longer, but will turn a 12x6 on a 4s LiPo without exceeding the max cont. 29A (in this case) presumably.

just my 2p worth.

 

Edited By Piers Bowlan on 10/07/2020 11:59:30

Peter Miller10/07/2020 12:59:58
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Believe it or not the model was nearly as aerobatic on that power as the original ic engine. IT just lost some of its crispness and edge.

The club members can confirm that

But then mine was pretty light.

Edited By Peter Miller on 10/07/2020 13:01:07

Low pass Pete10/07/2020 15:43:44
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Ballerina is a great model to fly and would fit the bill for a 1st low winger in my opinion. Mine has OS52 for power which is more power that the prototype had. She goes well. Has very nice take off and landing manners. I did a few mods to Peter's plan in that I inverted my engine and used 2 aileron servos instead of a single in the centre

However I have been impressed by my Fun Fly as well. Nice kit and easy to build. Just what I needed for lockdown. Used a 20 year old ASP46.

The choice is yours David

Cheers

Peter (Low Pass Pete)

Trevor Crook10/07/2020 15:50:24
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David, I have both the Ballerina and Ohmen, both electric powered. They are both excellent fliers, but I would agree with Peter that the Ballerina would be marginally the better first low winger. Being bigger it is not only easier to see, but is also just that bit "steadier" and being heavier will also handle wind gusts better.

As well as electrifying mine, I gave it an Ohmen style fuselage mounted u/c, just my personal preference as it's more forgiving of bad landings.

Mine goes well on a 3s 4000mAh setup with a 900kV motor pulling around 450W using a 12x(I think 6) prop.

ballerina 003.jpg

ballerina 001.jpg

David Clark 1811/07/2020 08:42:25
11 forum posts

Hi Trevor, thanks for the reply, and the advice. That looks really smart. I like the battery tray, how have you hinged the hatch? Is it done with covering film or is there an actual hinge?

Martin Harris11/07/2020 22:19:43
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Another of our mass build has flown - I missed the maiden a week or two ago but the builder was extremely pleased with the performance after I suggested trying a 4S battery this afternoon in the light of my trying the same earlier with one I've been trimming for a friend. This transforms the model from a pleasant flying model to a "high grin factor" fun machine!

img_0252.jpg

Edited By Martin Harris on 11/07/2020 22:28:50

Peter Miller12/07/2020 07:56:40
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Based n the way mine flies on a 3S I would say that using a 4S battery one would need ones Pampers on!!

Trevor Crook12/07/2020 08:21:42
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David, yes I used film to make the battery hatch hinge on the Ballerina.

Martin, love that colour scheme. I've used those US inter-war colours on a few sport models over the years. It looks good, gives good visibility in the air, and the basic markings are easy to make from film. Don't feel the need for 4 cells though!

Piers Bowlan12/07/2020 10:03:54
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Posted by Peter Miller on 12/07/2020 07:56:40:

Based n the way mine flies on a 3S I would say that using a 4S battery one would need ones Pampers on!!

Not necessarily Peter. By running it at a higher voltage, lower Amps can be drawn for the same power, depending on the prop used. This keeps the motor cooler and is usually more efficient, leading to longer flight times and a happier motor teeth 2. Alternatively when in 'hooligan modedevil' one can take advantage of more power available for aeros. The choice is yours.

Either way Peter, it is a testiment to your design skills that Ballerina flies so well on a 3s setup.yes

Peter Miller12/07/2020 10:49:11
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I rely on George at 4-Max to tell me what power combination I need for any given model.

Even my larger heavier models use the same power train and work well. I simply give George the specifications and he says use X.

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