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Mount a cowl with magnets?

Old 06-07-2007, 01:32 AM
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Default Mount a cowl with magnets?

I am to the point where I am ready to mount the cowl on the front of a Top Flite Corsair (.60 size). The cowl is in two pieces; a rear ring with mounting tabs to the firewall, and a forward piece meant to be glued to the rear ring. I was talking this over with a few friends and was not looking forward to reaching through the cowl, past a dummy engine, past the real engine, past the muffler, and past fuel lines to try to remove and then replace the screws that hold the cowl in place. It would require careful aim with a long screwdriver (or hex-driver).

Then one friend had an idea: Why not have the two cowl sections held together with strong magnets glued in pairs to the inside of the sections? Then the forward cowl section could be simply pulled off when you needed to access the engine! No external screws showing, no holes to crack and round-out! The rear section could stay screwed to the firewall.

Now, how about some opinions? Would the magnets hold with the vibration? Would vibrating magnets cause radio interference? I am planning to use an OS .91 2-stroke glow engine, so I don't think it would bother the engine. I have found some strong 'rare earth' magnets on ebay that I think would be strong enough, but would it work? See my diagram below...
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Old 06-07-2007, 01:45 AM
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Default RE: Mount a cowl with magnets?

It's been done before on small electrics and for canopy hatches on bigger models.
I'd add some alignment dowels to keep it in position.
Old 06-07-2007, 04:59 AM
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Default RE: Mount a cowl with magnets?

what about the weight?
Old 06-07-2007, 07:22 AM
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Default RE: Mount a cowl with magnets?

If you can come up with some system to support the weight, like dowels or alignment pins, and have the magnets only "retain" cowl from sliding, it should work.
Old 06-07-2007, 09:03 AM
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Default RE: Mount a cowl with magnets?

As far as interference, that possibility has been discussed in another forum and the opinions were that magnets would not cause any.....
Old 06-07-2007, 09:05 AM
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Default RE: Mount a cowl with magnets?

Several people running boats have been experimenting with rare earth magnets to hold on their cowls. So far, they're working well. The advantage of the rare earth ones is they are very powerful for their size/weight.
Old 06-07-2007, 09:19 AM
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Default RE: Mount a cowl with magnets?

No drawing ability but start to visualize this:

4 pieces of 1/4" diameter carbon fiber tube or rod, securely mounted every 90 degrees to the cowl.

They stick out the back 2" and will slide into 1/4" holes drilled in airframe.

This should support the vertical and horizontal movement of the cowl.

Then add several rare earth magnets on the fuselage with small steel plates in the cowl.

Or use mating magnets, whatever.

This should keep the cowl from moving forward.

Since when have you seen a cowl move forward anyway?

Maybe on a less-than-perfect landing but that's all.
Old 06-07-2007, 11:42 PM
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Default RE: Mount a cowl with magnets?

The dowels or rods to maintain the alignment is a good idea. Now if I can securely glue the magnets to a plastic cowl this should work. I have seen plastic coated magnets that look about right. Would you use epoxy, CA, or something else to glue them down?
Old 06-08-2007, 05:52 AM
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Default RE: Mount a cowl with magnets?

JB Weld may be better.
Old 06-08-2007, 06:16 AM
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Default RE: Mount a cowl with magnets?

Epoxy should work fine. Be sure to scuff up the cowling before glueing and you'll be OK.
Old 06-08-2007, 06:25 AM
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Default RE: Mount a cowl with magnets?

Use "rare earth" magnets. They are available several places on the internet. I bought my last ones from a seller on e-bay, "kjmagneteics". He has tons of sizes available. Good prices too. I have been using the 1/4 x 1/8" discs. He has 50 magnets for $10 & $5 shipping.

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