Tinamou - Page 3 - RC Groups
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Mar 31, 2008, 04:52 PM
Red Merle ALES VI
Curtis Suter's Avatar
I'm ready to start sheeting the cores. The wing ready to sheet is 1lb 13.2 ounces.

Looks like I should be around 50 ounces all up weight or less, which if at 50 ounces I'll have an "effective" wing loading of 7.3 ounces per square foot. My estimated wing area is 1275 square inches and for you folks paying attention I've increased the wing loading by 30% due to the fact the outer portion of the wing is not contributing to the lift, only stability.

I really like my paint scheme from Post #25 but it'll be a shame to cover up the beautiful wood. Hmmm, oh well the building continues!

Curtis
Montana
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Apr 02, 2008, 01:18 PM
Red Merle ALES VI
Curtis Suter's Avatar
Both outboard tip panels are bagged!

I weighed the panels of foam and balsa before bagging and the weights were:
First panel weighed 3.8 ounces before bagging and 5.2 ounces out of the bag.
Second panel was 3.8 ounces before bagging and 5.0 ounces out of the bag.

So with the addition of CF Tissue and Gorilla glue I have a weight gain of approx. 34%, if my math is correct.
Do you know how that compares to a glass layup? Sure seems strong!
Still should be around 50 ounces all up weight, that'll be great!

I think the area of each panel is 275sq inches, I'll have to verify that when I get home.

I'll post photos when I get some time at home, on the road today.

Curtis
Last edited by Curtis Suter; Apr 02, 2008 at 04:46 PM.
Apr 02, 2008, 01:24 PM
Red Merle ALES VI
Curtis Suter's Avatar
If I hadn't posted before this is the process I'm using to glue up the cores.

http://www.mackrc.net/patternwings2/index.htm

In short, 1/16" balsa sheeting glued on with gorilla glue and .2 ounce carbon fiber tissue in between for torsional strength. I used a .005 or .007 by 3/16" wide CF spar on top and bottom between the sheeting.

I am using Space Bags and a hand held brake bleed pump to bag them. So far I've been able to keep 6 in hg of pressure on them overnight.

Photos when I get home.

Curtis
Montana
Apr 02, 2008, 04:45 PM
Will work for foam
wingnutt's Avatar
Cloudy - are you having good luck with the PU glue curing in the bags? the method you used as a reference uses dead weight instead of a vacuum. is there enough air left in the bag for the PU glue to set up?
Apr 02, 2008, 05:59 PM
I eat only vegetarian beef
Skycruiser's Avatar
PU glue reacts with moisture in it's setting process. Like epoxy, it doesn't need air to cure. Interesting process, I've never heard of PU being used for balsa skinning before.

Nick
Apr 02, 2008, 10:56 PM
Will work for foam
wingnutt's Avatar
Skycruiser - i have always assumed PU glue needed oxygen to cure as well as moisture. the better i sealed the bottles the longer they lasted. I cant wait to try it now!

it is one of the best for skinning. looooong working time, creeps its way into every crevas so you hardly need more than it takes to make it look damp and you never have to worry if your mix ratio was correct or mixed well enough - its gonna cure.
Apr 03, 2008, 12:06 PM
Red Merle ALES VI
Curtis Suter's Avatar
Skycruiser, yep, they cure just fine. I leave them overnight.

Here's a couple of photos, the first one is in the bag under pressure and the second is of the completed tips. Notice the washout in the tips? Just what the flying wing needs!

Curtis
Apr 03, 2008, 02:29 PM
Surf's up!!
sixty9mustang's Avatar
Hey Curtis
Looking Great!!
Have you been flying lately?


Chip
Apr 03, 2008, 02:46 PM
I eat only vegetarian beef
Skycruiser's Avatar
Quote:
Originally Posted by wingnutt
Skycruiser - i have always assumed PU glue needed oxygen to cure as well as moisture. the better i sealed the bottles the longer they lasted. I cant wait to try it now!

it is one of the best for skinning. looooong working time, creeps its way into every crevas so you hardly need more than it takes to make it look damp and you never have to worry if your mix ratio was correct or mixed well enough - its gonna cure.
Back when I was an industrial chemist working with the stuff I used to put some in a small tin, mix some water in, and hammer the lid down real tight. Then I'd hide it in someone's waste paper basket with loose paper on top. after 15 min or so they'd go off like a bomb and scare the **** out of the poor victim. Then they made me department head so I had to stop.

I agree, great glue. I make balsa ply with it out of offcuts.
Apr 03, 2008, 04:24 PM
Red Merle ALES VI
Curtis Suter's Avatar
Quote:
Originally Posted by sixty9mustang
Hey Curtis
Looking Great!!
Have you been flying lately?


Chip
What, with this weather! Nope, no flying but perhaps Sunday, I'll advise.

Curtis
Apr 04, 2008, 01:16 PM
Red Merle ALES VI
Curtis Suter's Avatar
In the bare wood photos!
Apr 04, 2008, 01:18 PM
Red Merle ALES VI
Curtis Suter's Avatar
I'd forgotten to mention that I had the foam cores cut about five years ago by Laszlo Horvath at ComuFoamCore; http://www.compufoamcore.com/

Laszlo is a very nice guy and was very patient with me while I adjusted twist and airfoils. His service was top notch and fast and most importantly the workmanship of the cores was perfect!

Curtis
Montana
Apr 04, 2008, 03:26 PM
Will work for foam
wingnutt's Avatar
Abslolutely beautiful! very nice work.
Apr 05, 2008, 12:05 PM
Red Merle ALES VI
Curtis Suter's Avatar
Thanks wingnutt!

Here's the outer panel elevon and servo cutout.

Curtis
3" of snow in April!
Apr 05, 2008, 03:41 PM
Surf's up!!
sixty9mustang's Avatar
Hey Curtis
Great day for building! Should of been up last night when this stuff started coming down. Totally wet heavy snow, complete mess at the paper last night.

Very nice work, can't wait to see it fly. Am curious if you are going to use a single tow hook or a bridle set up.

Happy Building
Chip


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