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Old Aug 09, 2012, 06:05 PM
Electric Coolhunter
Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
14,466 Posts
Jut got this rare kit last weekend,so not build thread yet. But, there will be one!

The Model Merchant MB5 was a nominal .60 size glow model...sure wish there was something a little smaller than the main motor subject of this thread, but I might still go with it and adjust the prop choice, if possible, to get the model to have around 120-150 watts per pound, or perhaps around 900-1200 watts total.

Would prefer a 6S option, or even some setup with two 3S packs, but we will work with what we have to work with.

Didn't someone do something set up a bit like the old Byro drive where you could use one outrunner, with a power takeoff off the back of the outrunner using a belt and off the front using a gear and concentric shafts? Using a belt at the rear makes that shaft turn the same as the case of the outrunner and using a spur and pinon gear at the front makes that shaft turn the opposite direction.

Not as elegant as two outrunners, but might be easier going this route to get the exact power system and power levels I need.
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Old Aug 09, 2012, 06:11 PM
building building building!
aerophilia's Avatar
Melbourne Australia
Joined Jun 2006
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Check out the himax contra rotating motors, I think there are 4 in their range. I have a funny feeling they are missing something around the size you are looking for though.
The other option us to just have a prop spinning in a bearing, not connected to the drive.
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Old Aug 09, 2012, 07:09 PM
Electric Coolhunter
Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
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Quote:
Originally Posted by aerophilia View Post
Check out the himax contra rotating motors, I think there are 4 in their range. I have a funny feeling they are missing something around the size you are looking for though.
The other option us to just have a prop spinning in a bearing, not connected to the drive.
Already checked out the Himax series...the big one is too big and the next one down is still around 2000 watts, which is more than I need. The middle one of the five is 800 watts and a little too small for what I need. I need one that is at least 1200-1500 watts.

But, the second largest one might well serve propped down to draw around 1200-1500 watts. I got such a steal on the old MB5 kit (50 bucks, missing a couple of minor parts), I could go for a $350 motor if I had to.

I would rather fly it on one prop and skip the freewheeler than have a freewheeler.
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Old Aug 09, 2012, 09:43 PM
building building building!
aerophilia's Avatar
Melbourne Australia
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I had the same problem. They need that motor in the middle! I erred on the side of caution and got the bigger one
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Old Aug 12, 2012, 04:53 PM
Bypass Ratio = Infinity
scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
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Quote:
Originally Posted by Thomas B View Post
Some very nice work in this thread!

I recently scored a long sought after kit that this info might be quite useful in.

Many years back, around 1979, Model Merchant produced a .60 glow power almost ready to cover kit of the Martin Baker 5, from the Dan Parsons design.

I actually got to fly Ted White's very nice MB 5 from this kit in the early 1980s. He used to campaign one in the local scale competitions. A superb flying model.

Built up balsa fuse, assembed and mostly sanded out...call it 90-95% done. Balsa covered foam wings and tail surfaces.

This motor might do the trick, although it is a little large and heavy for this particular model.
Oh man, it would be blasphemy not to contra an MB5 . I agree that it is too bad that no one makes something in between the motor mentioned already. Depending on the wing loading desired you could try one of the larger motors as you mentioned. I think the CR50 with 14" props would give you 1200 watts or so on 4-5 cells. How big is the spinner on the MB5?
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Old Aug 13, 2012, 05:53 PM
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TripleW's Avatar
Prescott, Arizona
Joined Feb 2010
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I was unfamiliar with the MB-5.
So here is a link for dummies like me!

http://en.wikipedia.org/wiki/Martin-Baker_MB_5
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Old Aug 13, 2012, 10:37 PM
"the bouncer"
mackone's Avatar
Australia, VIC, Vermont
Joined Nov 2006
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It very similar in profile to the CAC CA-15

http://en.wikipedia.org/wiki/CAC_CA-15
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Old Aug 17, 2012, 05:36 PM
http://roys-rc-tv.webs.com/
Basingstoke Roy's Avatar
United Kingdom, England, Basingstoke
Joined Oct 2005
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Hi all
If you want to know a bit more about the MB5 I've added some more links below.

http://www.martin-baker.com/about/mb1-mb5
unfortunately they seem to have removed the link to Mr Martin’s Memorable M.B.5" – A Reprinted from Air International, 02/79. A very good piece on the history of the MB5, I may still have the file some ware, if I can find it I will PM it to you (but it wont be for a couple of weeks).
Also look out for the book, "Sir James Martin: The Authorised Biography of the Martin-Baker Ejection Seat Pioneer"

Here's my take on the MB5 & a how to build your own 1400W 4cell motor

My TCM3.1 contra motor
My1/8th scale MB 5
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Old Dec 15, 2012, 03:32 AM
building building building!
aerophilia's Avatar
Melbourne Australia
Joined Jun 2006
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Any news Scatsob? I see ESM have brought out Generation 3 of their retracts......
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Old Dec 15, 2012, 04:23 PM
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TripleW's Avatar
Prescott, Arizona
Joined Feb 2010
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This project was for sale awhile back.

Here it is.
http://www.rcgroups.com/forums/showt...ht=esm+spitfir
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Last edited by TripleW; Dec 15, 2012 at 04:44 PM.
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Old Dec 15, 2012, 05:49 PM
building building building!
aerophilia's Avatar
Melbourne Australia
Joined Jun 2006
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Bummer! Thanks for the link TripleW.
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