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Old Jan 30, 2014, 11:17 AM
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United States, MN, Brooklyn Center
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I can't recall the thread where we started to go into the "stacked weight" vs vacuum for skinning foam core wings. Is that where your data above comes from? I know I wrote some stuff on the subject so just want to be sure it is not mistaken.
That sounds right...

I should still pull the vacuum to 5-6 Hg though... correct?

I have a lot to learn.


Brian
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Old Jan 30, 2014, 11:27 AM
R_G
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Brian,

When I bagged my UFO wings I used about 7" Hg because that's what the vacuum pump would pull and I didn't have a regulator or a bleeder valve. But after fooling around with it for a while(bleeding off the vacuum) I came to the conclusion that 3-4" Hg is all that is needed. Just my $.02.

Ralph
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Old Jan 30, 2014, 12:05 PM
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Originally Posted by EscapeFlyer View Post
That sounds right...

I should still pull the vacuum to 5-6 Hg though... correct?

I have a lot to learn.

Brian
Brian,

can you remind me of the thread where the stuff was hashed out? Please post a link.

I think you can probably get away with 5-6 inHg (2.5-3 psi) but I agree with Ralph. I bleeder or regulator sounds like the way to go if your pump is rated to 6 inHg. By the way, you have to specify what height unit you're using when specifying pressure in mercury barometers. If you just say Hg, it could be mm, cm, in, whatever - those are the more typical units though. Ironically I learned a metric/imperial hybrid in school as they taught us using 760 mmHg as atmospheric reference. Naturally psi was spoken about next... It took another several years before someone else spoke about bars and Pascals.

If you were to use 3-4 inHg as Ralph suggests, you'd be at 1.5-2 psi or about 1000-1400 pounds of weight per wing. BTW, I forgot to divide by two in the above as the entire wing core panels are ~700 sq in - not each panel. In other words, with 1.5-2 psi you'd have a weight equivalent of 500-700 pounds per panel. I'm sure that is way more than any staked weight that at least I have put on top of my shucks when skinning them on a table! It also seems to match the figure of ~600 pounds that you mentioned and was discussed in the previous thread.

I assume you'll be bagging each wing panel separately - not that it matters for the calculations above. 1 psi vacuum is what it is whether you have 1 sq in of wing or 1000 - makes no difference!

Otherwise put, pressure is pressure.

David

P.S. All this pressure talk reminds me of my younger days as a scuba diving leader in the tropics. We used to take tours out in the Mexican Caribbean - Cancun and Cozumel mostly. Even in the 80's it was typical to use aluminum tanks (with a 1/2" wall thickness!) which were filled to 80 psi... You can imagine what happens if a regulator valve is defective and it's over pressure escape valve is defective. Before the tank explodes, the regulator valve will be shot off... and will land about a mile away even if it is shot straight up into the air. I witnessed this once only and the noise sounded as if a grenade had gone off. Fortunately the person filling the tank was not injured. it also sheds some light on why tanks are put in water when filled. Not only does it cool the metal off by absorbing the heat but it also is a safety measure in case one were to literally go off - much harder to expand liquids than gases...
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Old Feb 15, 2014, 08:38 PM
CPA# 39
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Do your best to ignore the glob of glue on the nose. That will all get cut off and replaced with a block of balsa I will sand to shape....

Do you see the header? This is the new 1.5" rise fuse top header NovaRossi is selling.

I believe that the guys at SMT are probably tired of me begging and pleading and calling and emailing already! Lol... They got this rolling for us!

My foam cores should be here soon. For now I will be slowly whittling away to the proper shape on the fuse...

I MAY actually have a Great Escape in the air this spring! VERY excited! Soon to follow with the Escape and Dirty Birdy.

Then I will take a break from building for a while to get some serious stick time. I gotta master some patterns this year, and try to become a CD.

I hope you enjoy the pictures!

Brian

(Wow... I really need to stop, clean, re-organize, and fix that drawer. That's a little embarrassing. )
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Old Feb 15, 2014, 10:10 PM
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Sin of all sins... A glob of glue on your nose

It's looking good Brian. It will be in the air sooner than you think.

Ken
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Old Feb 15, 2014, 10:54 PM
CPA# 39
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Originally Posted by kenh3497 View Post
Sin of all sins... A glob of glue on your nose

It's looking good Brian. It will be in the air sooner than you think.

Ken
Lol... Thanks.

My daughter took that pic. I liked it enough to want to post it, but that ugly on the front nose bugs me. Once finished, no one would ever know about it anyhow.

Brian
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Old Feb 16, 2014, 08:13 AM
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Looking good Brian. That engine looks like horsepower monster!

Mike
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Old Feb 16, 2014, 11:04 AM
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Wrong, Brian!! We have ALL seen it.

Wish my G.E. was that far along, rather than still in the box

Jim
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Old Feb 16, 2014, 01:27 PM
CPA# 39
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Thanks Mike!

I am excited because this engine did swing well over 14,000rpm with an 11X8 APC at break in. It's the older NR model built in 2002. And to think my Speed 13 will do even better!

Verticals and Knife-Edge flight should be a blast. I'm thinking it should be a good rolling circle airplane as well.

Jim-

Rub it in why doncha...

Just so you know, the GE builds much easier than the Escape. It's more difficult to plumb though.

As much as I like the Dave Brown mounts, I find the Sig Twin Beam glass mounts to be a better engine mount choice for the GE.

Brian
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Old Feb 17, 2014, 05:59 PM
Zor
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Originally Posted by EscapeFlyer View Post
Thanks Mike!

I am excited because this engine did swing well over 14,000rpm with an 11X8 APC at break in. It's the older NR model built in 2002. And to think my Speed 13 will do even better!

Verticals and Knife-Edge flight should be a blast. I'm thinking it should be a good rolling circle airplane as well.

Jim-

Rub it in why doncha...

Just so you know, the GE builds much easier than the Escape. It's more difficult to plumb though.

As much as I like the Dave Brown mounts, I find the Sig Twin Beam glass mounts to be a better engine mount choice for the GE.

Brian
Brian,

I sent you an email on 04 Feb 2014 at 9:33 PM
I did not hear from you for one month.

Please advise.

Zor
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Old Feb 17, 2014, 08:06 PM
CPA# 39
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Originally Posted by Zor View Post
Brian,

I sent you an email on 04 Feb 2014 at 9:33 PM
I did not hear from you for one month.

Please advise.

Zor
Go away.
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Old Feb 20, 2014, 07:09 PM
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Brian,

Looks like you should be able to move right along now - good stuff.

Quick question since I figure you might have both, if not all three NR fuse top headers. How much rise is there in the 402 and 403, respectively? I take it this last is 1.5" but is that center to center? 1" in the 402?

Thanks, David
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Old Feb 20, 2014, 09:06 PM
CPA# 39
EscapeFlyer's Avatar
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Hi David.

I will double check exactly tomorrow... if I make it thru Snowmageddon! I may be stuck here at work until tomorrow sometime. This storm is a doozey.

Anyhow... I do have the 402 and the 403 headers. Memory tells me the 40402 is 2 inches center to center and the 40403 is 1.5 inches center to center.

Look for a more precise measurement as soon as I can answer tomorrow-- unless Dave, Buddy, or someone else jumps in first.

Brian
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Old Feb 20, 2014, 10:07 PM
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Much appreciated Brian.

Sounds like the 402 is the "inverted" header (Magic/Skymaster style) while the 403 is the "deep fuse top" header (Escape/Deception/Arrow) style.

Lines extended from the center of the entry and exit points will provide the offsets.

David
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Old Feb 21, 2014, 07:35 AM
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Good to see this thread reopened, thank you. I have enjoyed following it.
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