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  #31  
Old 05-01-2013, 03:50 PM
rwhittier rwhittier is offline
 
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Location: Glendale, AZ
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Default Good idea..

Meanwhile, thanks for the email copy.


Quote:
Originally Posted by GrayHawk View Post
Huuuummmm! Given the continuing nature of these requests, give me a little while and I will put the files on one of my servers. Then I'll post a link to download the files.

I might mention that what I have for the Farn Reed "Bladder Buster" tanks is just a collection of photos, sketches, original instructions. There are no real drawings or plans.

GH
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  #32  
Old 03-28-2015, 11:22 AM
BillL BillL is online now
 
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Default Experienced Builders, Aero Engineers . .Help needed

Here is a picture of Bob Axsom's tip tank. Amazingly the other picture is still posted at the beginning of this thread.

I have all the documents listed earlier here, and was thinking about building some from scratch. In looking at the picture the rib, it appears there are no flutes and there are definitely bosses welded to it. Also, unseen, there are some baffles internally. At least one at 20" back from the leading edge. A vertical row of rivets closer indicates there may be two baffles.

So - 1. what material might be appropriate for this rib, that can be welded, and 2. what construction method can yield a flat piece with no flutes on the bent flange?

Thanks

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  #33  
Old 03-28-2015, 11:35 AM
David Paule David Paule is offline
 
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Bill, probably both 5052 or 6061 alloys can be welded. I know the 6061 can be. They can be formed, if soft, with a hydropress (Univair can do it). They can be heat-treated after forming, might also need stress relieving, but the welding will knock the strength down by at least half and easily more.

In the photo it looks like the end rib is riveted to the skin.

You're aware of the effects of increasing the span on wing's ability to carry flight loads, right? There will also be an effect on the flutter speed.

Dave
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  #34  
Old 03-28-2015, 11:43 AM
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edsong edsong is offline
 
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Default Spins

I probably wouldn't spin it with the tanks full.
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  #35  
Old 03-28-2015, 11:52 AM
BillL BillL is online now
 
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Dave, thanks for a quick response. Hydroforming is probably out of scope. That flange would certainly have to be compressed, shrunk, yielded, to yield a 90 deg bend nicely from a sheet.

Regarding flutter, Bob A. mentioned he had pushed his speed to at least 190 its, but I could not find any actual flutter information posted. I had read all the Farn Reed posts before and just reviewed what I could find once again. Apparently, Farn is no longer with us.

There are other types of extended range , ER, tanks that would not affect the wing length. There remain a number of issues to be considered. This one was just the construction.
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  #36  
Old 03-29-2015, 07:22 AM
cccjbr6 cccjbr6 is offline
 
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I bought Bob's plane from his estate. The vendor materials are a bit scant but they do not mention flutter or VNE issues. They do mention (1) that the full tanks increases take off roll by 100 feet and stall speed by 2mph, (2)empty tanks decreases stall speed by 2 mph, (3) ride in turbulence is more stable, (4) aerobatics with the tanks on are not recommended." Curiously the materials also say W&B are not affected. I would think and extra 18 inches of wing span would increase useful load somewhat.
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  #37  
Old 03-29-2015, 09:11 AM
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GrayHawk GrayHawk is offline
 
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For those interested in the Farn Reed tanks, the zip of collected photos and documents is at:

http://www.cherryfamily.net/bill/n63...d/?page_id=870

GH
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  #38  
Old 03-29-2015, 01:09 PM
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Bubblehead Bubblehead is offline
 
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Quote:
Originally Posted by cccjbr6 View Post
I would think and extra 18 inches of wing span would increase useful load somewhat.
Be careful here. Extending the wings increases bending moment at the root, and increasing load will do the same (plus increasing shear load). The structure weighs something, which REDUCES useful load unless you raise max gross.

I'm not sure on what basis you're thinking useful load would increase. And yes, I am an engineer, although not an aircraft structural engineer.
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  #39  
Old 03-29-2015, 01:12 PM
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Bubblehead Bubblehead is offline
 
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Quote:
Originally Posted by GrayHawk View Post
For those interested in the Farn Reed tanks, the zip of collected photos and documents is at:

http://www.cherryfamily.net/bill/n63...d/?page_id=870

GH
The link is not working for me. Any suggestions?
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  #40  
Old 03-29-2015, 02:22 PM
RV-4 RV-4 is offline
 
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Default Extended range tanks

The link doesn't work for me either..

Thanks

Bruno
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