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The Ohmen

My first electric powered aerobatic model

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Peter Miller08/11/2019 08:30:44
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Have a look at Vortexvacform for their huge range of canopies

**LINK**

Martin Harris28/11/2019 23:44:00
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Apologies if this has already been covered but I have a query about the wing braces/joiners. The golden rule with paper plans is to go by dimensions rather than measurement but I've noticed rather retrospectively that the spar slots shown for R1 and the inboard R2s clearly appear to be an extra 1/8" wide to accommodate the wing joiners.

However, both the printed dimension and plan view of the wing joiner appear to agree that these parts are made from a single layer of 1/16" ply.

I've made mine with a single piece 1/16" joiner but I'm confident that the full depth would more than make up for any lack of strength if the intention was to use what would be effectively 1/4" by 1/8" strips.

What was the original designed thickness of the wing joiners/dihedral braces?

Edited By Martin Harris on 28/11/2019 23:46:45

Peter Miller29/11/2019 08:58:03
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My original plans and the magazine plans state 1/16" ply joiners. These have proved adequately strong.

These have been proved with a lot of flying and one very hard thump.

Sometimes the person who redraws my original drawings makes a few errors.

Don't forget that the dihedral braces only form a small part of the strength of the joint. The whole area of joining the two wings is part of that joint and then the covering adds even more strength. and Moderate to say the least The omen is a very light model so G forces will be light.

I have a G meter and one of my bigger i.c powered models was put into a terminal velocity dive and the pulled out with full up elevator.

It recorded 24.8G which meant that in effect during the pull out it weighed over 90 lbs.

Martin McIntosh16/03/2020 19:08:56
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I decided to pinch the OS26 from my Peacemaker and fit it to mine. As usual there was a little more to it than I anticipated including making a new cowl which does not quite follow the right nose line due to having to use a couple of the original engine mount screw holes. The finished job looks OK ish.

Even though I used a 5 cell Eneloop as far back as possible the cg is a tad forward at the moment but fine for a test flight.

Some pics.

ohmen 003.jpg

ohmen 001.jpg

ohmen 004.jpg

ohmen 005.jpg

ohmen 002.jpg

Peter Miller16/03/2020 19:24:33
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THat looks fine.

CG a fraction too far forward is always better than too far back

I will look forward to hearing how it goes on the FS26. Should be really nice.

Martin Harris16/03/2020 20:16:40
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Mine's finished too - but we've just had to postpone our annual pre-season model show, due to be held next week, which was to feature a club mass-build where we've managed to encourage a number of first time builders over the winter with great results. I had been holding back until I could post photos of the expected crop of Ohmens posed together...

20200310_162436.jpg 20200310_162457.jpg

Mine was scaled down to 40" wingspan to facilitate the use of a little OS20FS which has been looking for a home - hence the GLOhmen 40 decal - and this is my take on mounting the engine in this electric powered design - the removable cowling was deleted and I provided captive nuts in wooden bearers passing through a slightly relocated F1 to F3:

20200316_194218.jpg

C of G wise, this gives a clue to the location of the receiver battery...

20200316_194228.jpg

Hopefully the bumper bundle of Ohmens will get together once the Coronavirus dust has settled.

Peter Miller16/03/2020 21:02:25
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That looks vey smart too.

Martin Harris08/04/2020 21:23:26
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Who says the art of building is dying?

As mentioned previously, our club decided to hold a mass build over the winter and we've collected pictures of the product of the exercise (I'm assured that the last one is basically an Ohmen). There are at least two more at an earlier stage of construction as well which I don't have pictures of. This means that almost a quarter of the membership are directly involved.

What is particularly gratifying is that among the models shown, at least 4 are from novice builders and may not be the ones you might think - let's hope they are inspired to continue with this aspect of the hobby!

53 a - martin impey - in progress - ohmen.jpg70 a - tim eastgate - ohmen.jpeg62 b - derek webb - ohmen.jpg69 b - sue walby - ohmen.jpg60 a - brian lawrence - ohmen.jpg68 a - mick eames - ohmen.jpg61 a - dave parsons - ohmen (miles magister).jpg63 c - harry atkin - ohmen.jpg67 a - martin harris - ohmen.jpg66 a - john williams - ohmen.jpg64 a - james atkin - ohmen.jpg65 b - joe beavis - ohmen.jpg71 c - stephen edge - ohmen.jpg

Peter - thanks for providing the design...now we just need to get the chance to fly them!

Peter Miller09/04/2020 08:33:52
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10966 forum posts
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Thank you for all those pictures. A wonderful mass build.

I really like to see people adding their own customization to the models and there an some people have had real fun with that.

And a really big congratulations to Sue Walby. It is really good to seee a lady building models.

I shall look forward tohearing how the flying goes once the dreaded Lurgi has gone.

I wil say that it does give me a big lift to see one of my plans being apreciated so much.

THANKS

james brough27/05/2020 18:28:20
3 forum posts

hi have built the peter miller the ohmen but have lost the page where it gives you the cofg and worst of all the control throw figures can some one please help

kc27/05/2020 19:00:54
6427 forum posts
173 photos

James, welcome to the forum.

The article gave control movements ailerons 3/8inch or 10mm each way, elevator 5/16inch or 8mm each way, rudder 1 inch or 25mm each way.

.  Article says CG 2 and 3/8 inch or 60mm back from LE.   Plan measures 62mm actually so almost same.

Edited By kc on 27/05/2020 19:06:11

Edited By kc on 27/05/2020 19:08:13

james brough28/05/2020 15:45:26
3 forum posts

thanks very much for that info should try to fly the plane next week at 81 and only a limited amount of time flying I MAY HAVE A FEW PROBLEMS wish me luck

Peter Miller28/05/2020 18:24:43
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Posted by james brough on 28/05/2020 15:45:26:

thanks very much for that info should try to fly the plane next week at 81 and only a limited amount of time flying I MAY HAVE A FEW PROBLEMS wish me luck

Set low rates at about a bit less than those for the first flight if you are out of practice.

I am 82but I am used to throwing them around with wild abandonment

Edited By Peter Miller on 28/05/2020 18:25:31

james brough04/06/2020 16:10:17
3 forum posts

i have only been flying 2 years and still a very slow learner but with my mentor barry bailey the ohmen flew for the first time tuesday afternoon barry took it up and set it up and i had a short flight with it and barry landed it it flew well and he said it was a good flyer but a bit too sensative for me at the moment i have a lot of learning to do yet

Peter Miller04/06/2020 18:00:51
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WellDone James.  I am so glad that you have had a good maiden flight and enjoyed it.

Barry is right. It is set up with plenty of control and in your case would be a bit twitchy.

I hope you have many more great flights with it

Edited By Peter Miller on 04/06/2020 18:02:00

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