RE: Red Tail Project TF P-51C with scale size 5.5" Spinner  
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RE: Red Tail Project TF P-51C with scale size 5.5"... - 11/19/2007 5:59:25 PM   
Spychalla Aircraft



Posts: 499
Joined: 1/9/2003
From: Watertown, WI, USA
Status: offline
quote:

ORIGINAL: v6goose
Would you explain your comment "...This cowling uses the TF kit reference lines for engine placement. They were accurate when using the 5.5" Spinner.

Is this the TF supplied cowl? If so, how is it correct from a scale perspective?

I have read some threads that suggest the nose slopes towards the spinner ring too fast after the firewall and have seen people raise the engine 1/4" and add the 5 1/2" spinner to 'correct' this.


Here is the explanation. It's true that the TF cowling slopes too much down to the spinner ring, that is what makes the front of a TF mustang look so ackward. Part of the problem is that 5" spinner they use. This is not a TF cowling and a TF cowling is not correct from a scale perspective, but their engine C/L elevation is.

What you see here is not a TF cowling at all. It is a built-up plug for the mold that I will be making for a Spychalla Aircraft cowl that uses a 5.5" spinner. The 5.5" spinner takes the top up 1/4" without making any other adjustments. It looks pretty good. I don't know why people are motivated to go an additional 1/4" up. That would make the top too straight in my opinion. You can see the finished shape from the side picture above. It looks very good from all perspectives in my opinion and compares favorably to my 3-view measurements. So, the proof is in the final product. Leo

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       Post #: 26

RE: Red Tail Project TF P-51C with scale size 5.5"... - 11/19/2007 6:16:36 PM   
v6goose



Posts: 616
Joined: 2/9/2003
From: Ottawa, ON, CANADA
Status: offline 		Great... thanks for the explanation.

What is the lead time for your cowls and how much would they be?

Cheers

Goose

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RE: Red Tail Project TF P-51C with scale size 5.5"... - 11/20/2007 12:36:14 PM   
Spychalla Aircraft



Posts: 499
Joined: 1/9/2003
From: Watertown, WI, USA
Status: offline 		Goose,

I will send you a PM. It violates forum policy to answer you directly and the posting would likely get pulled. I will get it set-up as an advertisement on RCU when it is ready to go. So you can't miss it.

Leo

(in reply to v6goose)
       Post #: 28

RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 11/20/2007 1:27:54 PM   
v6goose



Posts: 616
Joined: 2/9/2003
From: Ottawa, ON, CANADA
Status: offline 		Thanks a lot.

Goose

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 11/24/2007 6:46:20 AM   
Spychalla Aircraft



Posts: 499
Joined: 1/9/2003
From: Watertown, WI, USA
Status: offline 		Performed a final scribe of reference lines on the plug and then wet sanded it to a 400 grit. I made an ejector plate at the front of the mold to help with removal of the part. The bolts and T-nuts will be captured in the mold and act much like a fly wheel puller to help get the part out. I then applied 3 coats of wax, a coat of PVA, and then the orange tooling gel-coat. It looks pretty rough with just the gel-coat on it, but you have to remember that the smooth surface is against the part, not what we see. The tool is then laminated with Vinylester Resin and random strand fiberglass. Leo

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 11/24/2007 3:42:13 PM   
Baldeagle


 

Posts: 1448
Joined: 2/2/2002
From: Lakeside, AZ, USA
Status: offline 		The spray gun you are using for the gel coat. is it different than a regular paint spray gun? Looks good . Thanks Rich

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 11/25/2007 10:41:01 PM   
Spychalla Aircraft



Posts: 499
Joined: 1/9/2003
From: Watertown, WI, USA
Status: offline 		Rich, It is different. The gun itself is similar, it is a Binks Model 7 which is obsolete these days, but it is a very nice gun. The difference it that it is fitted with a pressure pot. You can see the regulator on the line and a tube that goes up to the pot. I run 5 psi on this pressure pot and it is enough to spray material that has a high viscosity like gelcoat.

I popped the mold today! Wonderful! It is the moment of truth. You never know if it is going to stick or if your going to destroy something getting it apart. No problems this time. The push-out disk I made at the front worked perfectly. Just like a flywheel puller. I just walked the plug out of the mold with no trouble at all. The same should be true for each part I make as well. Parts are just a few steps away. I need to make the removable undercut features for the exhaust stacks on each side and then I will be molding cowls.

You can see the step feature on the side of the mold that will be used for green trimming the partially cured part. This feature ensures accurate placement of the cowl every time for a flush fit to all edges of the Top Flite P-51 fuse. No overlap. Today I realized that by keeping the firewall scribed engine placement this cowl can actually be used to retrofit existing TF cowls to repair or dress-up the front of a tired Mustang without having to move the engine. Something to think about. Leo

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 11/25/2007 11:53:29 PM   
Ram-bro


 

Posts: 2014
Joined: 1/22/2002
From: Bennington, NE, USA
Status: offline 		Leo are you sayingh that I could retrofit my p51b with your cowl ithout having to change the placement of the motor? That would be fantastic

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 11/26/2007 12:29:25 AM   
Spychalla Aircraft



Posts: 499
Joined: 1/9/2003
From: Watertown, WI, USA
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quote:

ORIGINAL: Ram-bro
Leo are you sayingh that I could retrofit my p51b with your cowl ithout having to change the placement of the motor? That would be fantastic

Ram-bro, If your P-51B is built from a 1/5th GS Top Flite ARF or ARC then this cowling will work for you without having to move your engine. The most you would have to do is shim the engine forward a bit to meet up with the new 5.5" spinner position. I will know the relative fore/aft distance to the TF cowl once I get one of these cowls done from the mold.

If you built your P-51B from the 1/5th GS Built-up balsa kit or from some other source then you are on your own. I do not know if the firewall size and contours are close or not. Leo

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 11/26/2007 1:29:35 PM   
Baldeagle


 

Posts: 1448
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From: Lakeside, AZ, USA
Status: offline 		Leo thanks for the info on the spray gun, I just happen to have two of them. One I bought when I was in high school some 43 years ago. I just need to make a presure pot.
I have been wanting to try the gel coat for a long time. I need to make some wheel pants for my 85 in Val. Thanks Rich

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 12/3/2007 3:38:37 AM   
Spychalla Aircraft



Posts: 499
Joined: 1/9/2003
From: Watertown, WI, USA
Status: offline 		Rich, I wouldn't recommend "Making a Pressure Pot". This is the type of item you buy. You could hurt yourself by creating a pressure vessel that is not designed to take pressure. BINKS made the pressure pot I am using and it is very robust.

Progress shots. My cowling will have recessed areas for the exhaust stacks. This will help create the illusion of realism where they look like they come from behind in the engine compartment. You can see the wooden inserts I have made for the mold. They will come out with the part when de-molded. Wood actually works great. It takes wax well and is repairable if you damage one. The cowling will also have recessed areas for the two side screens. I had to figure out how to make these before I would know the right thickness for the recess. They are easily created from 1/64th ply using a soldering iron and a sharpened brass tube. Surprisingly a 5/32" (.156) O.D. brass tube fits right in the end of my Weller SP23L 23 watt soldering iron making this tool really easy to make. It burns fairly clean holes and I was able to make this side plate in less than 10 min. So this cowl design will have open screen holes which should look great and add to cooling. In the final shot below I am laminating an insert for the tool that will be the lower removable hatch. I decided to make it thick with 5 layers of 6 oz. cloth. The theory is that this will be thick enough that I should be able to counter sink flat head screws for attachment. The hope they will look like Deutz fastners when done. We will see. Leo

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< Message edited by Spychalla Aircraft -- 12/3/2007 3:41:25 AM >

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 12/3/2007 12:51:42 PM   
Baldeagle


 

Posts: 1448
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From: Lakeside, AZ, USA
Status: offline 		Leo very nice work. Thanks for posting. Never to old to learn something. Rich

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 12/6/2007 5:42:28 AM   
Spychalla Aircraft



Posts: 499
Joined: 1/9/2003
From: Watertown, WI, USA
Status: offline 		I've struggled for weeks thinking about a good attachment method for the lower cowl, but today I figured it out. I typically hate screws because they stick up and hidden fastening methods can be very complicated. The criteria are that it has to look scale, allow easy access to the engine, and not get elongated or destroyed by engine vibration. I've chosen to countersink #5 Flat Head Machine screws at the scale locations of the Deutz fasteners on the real cowl. To do this I purchased a special countersink with an 82 degree included angle from McMaster-Carr. It works great! You can see the trial piece I made to test the concept. The extra thick hatch has plenty of material thickness for the countersinks. The screws will be captured on the back side by small tapped aluminum plates that I will glass into the cowling during manufacture. I am working on adding the lower flange to the tool and it was a good time to test the open hole size to make sure you can pass an engine through it. Here my DA-50 easily passes through the middle of the flange frame with plenty of clearance. So the idea to bond the cowl permanently to the fuse and make it seamless looks like it will work. All engine installation and access will be from the lower hatch. Next steps are to add a flange to the main tool and to make a separate hatch tool. Leo

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RE: Red Tail Project TF P-51C with scale size 5.5&quo... - 12/9/2007 6:06:42 AM