Q-40 Racing Discuss AMA 422 and any other variants of Quarter 40 racing

Polecat Nose

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Old 03-11-2010, 12:10 PM
  #1  
Fly Fast n Left
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Default Polecat Nose

After reviewing Lee's method of mounting the tank up high and reinforcing the nose I decided to put my own spin on things. I first apologize for the poor picture quality, my phone was the closest thing near by when I was doing this.

When the front section was cut out of the saddle I was concerned with the hoop strength and overall rigidity of the wing bolt area. I decided to create a small half bulkhead along with an extended gear plate to tie it together and then a carbon tube to support the tank and provide more strength.

First I started to create the carbon tube to support the tank. The tank was wrapped with a layer of blue masking tape and then clear packaging tape followed by 2 coats of wax. Then I layed up a layer of 2oz glass followed by the carbon and put a piece of glass over the seam.



While the tank was curing I created some templates from some scrap depron laying around. I wanted to tie in the wing bolt hold downs and the fuse together well and provide an area to pot the wing bolts as well.


Trimmed the carbon tube real quick to get a test fit. I cut the tube roughly in half and left about 3/8" protruding through the wing saddle area into the nose.


To make by bulkead and gear plate I used a piece of 1/32 ply with a layer of carbon in it. I traced my foam templates and sanded to fit. Then tacked everything in place with some CA and followed that up with milled carbon and some resin to create a small fillet on all the joints. I also packed the mixture around some waxed wing bolts. I applied some carbon tow between the two bolt hold downs across the bottom of the tank support to make it very rigid.



Pic looking in the engine cut out


Now the tank slides perfectly into the tube and can be held in place with a piece of double sided tape between the tank and the tube to keep it from moving around.

Finished product. (I still have to clean it up a bit more)


Hope this is useful for someone! I think it will hold up very well.

Best,
Jacob
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Old 03-11-2010, 01:08 PM
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Default RE: Polecat Nose

Nice!!.. What do you think you added for weight?

I've got my old polecat all stripped down to repaint and fix a few years worth of dings.. I might have to give that a try..
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Old 03-11-2010, 01:18 PM
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Default RE: Polecat Nose

Thanks!

I dont believe I have added more than 1/2-3/4 of an ounce. The benefits of having the tank mounted higher and the engine run better rate much higher to me than a slightly lighter plane. I feel really good about how it turned out. It is very very strong. Before the modification I could squeeze the wing mount area and the fuse would deform, now there is no deformation at all. I have a nice thick firewall to install as well to continue with keeping the nose rigid.

Jacob
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Old 03-11-2010, 01:39 PM
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Default RE: Polecat Nose

What weight CF did you use?
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Old 03-11-2010, 02:02 PM
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Default RE: Polecat Nose

I think it was like 5.7. or 5.8, something right around there. I think lighter fabric would be ok as well.

Jacob
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Old 03-11-2010, 02:13 PM
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Default RE: Polecat Nose

I'm not positive, it could of just as well been dumb thumbs, but I'm pretty sure I saw the nose of my polecat wobbling and breaking free of the fuse just prior to plowing it into the ground in Muncie last year.

I had modified the nose and wing to fit a tetra tank, but did not do much to reinforce the area. I truly believe this modification would have saved my plane last year.
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Old 03-11-2010, 02:22 PM
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Default RE: Polecat Nose

Dave,
I completely agree. I had a wing fall off my first polecat in Phoenix a few years ago. I am confident that this one should stay on! I think by just potting the underside of the wing blocks one could get by, but for me regaining all the hoop strength and connecting the wing mouting blocks was a big deal.
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Old 03-11-2010, 07:28 PM
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Default RE: Polecat Nose

Good job Jacob!! Workshop semi clean and your stuff is on the workbench. Anxious to see it fly!
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Old 06-28-2010, 09:03 PM
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Default RE: Polecat Nose

Well last weekend was the acid test for the polecat setup. Jacob was able to get 10 laps of racing without slowing down!! Although it wasn't as easy to needle as the Jett in my 2 sweet, he really didn't have any problems. I would highly recommend this mod or something similar if you like the Polecat.
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Old 06-29-2010, 07:04 AM
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Default RE: Polecat Nose

I ended up doing a similar mod on mine.. I used a Tetra tank and 5.7oz CF cloth.. I had to do a little grinding on the plastic around pressure fitting to remove it but other than that it worked really well..
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Old 06-29-2010, 08:54 PM
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Default RE: Polecat Nose

Lee,
Im glad to see that you tried this style of mounting the tank. Post some pics if you get a chance! So far I have had good luck with getting consistent engine runs. I can run 13-14 laps without any drop in speed measured using a radar gun.

Jacob
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Old 06-30-2010, 09:59 AM
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Default RE: Polecat Nose

I had a minor mishap with mine and some grass that was a little too long. Nothing too serious but still a couple cracks to fix before the Nats.. I'll see about getting some pics of the tank install during the rework this week.. I didn't have any engine issues regarding a lean run, the thing was going pretty good, even on a new engine that's still getting broke in..
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