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Nov 06, 2019, 10:02 PM
Entropy is happening!
Jim.Thompson's Avatar

Slightly off topic......apologies Hoppy!


Quote:
Originally Posted by brett.c
Looks good. Has a huge wing area so weight will not be an issue............
Yes Brett; 35 sq.dm.
Apologies to the "old world" system users, I don't know what this is in pounds/ounces/sq. ft/ sq. furlong/sq. yard et. al.................

Quote:
I have 1200g planes with way less wing area and they fly fine.
3536 900-1000kv, 2200-3000 4s, 50A ESC 11x5.5 prop should perform well. Of course more is often better.............
I found that I need more weight in the nose to balance. More that two of the 3S 1600 ma/hr. LiPo batteries that I have in stock.
So........
I did a bench run test with 4S x 3000 ma/hr. battery, and a 10 x 6 folding propeller.
Fantastic results: 400 watt @ around 28 amps..........within the max recommendations for this little motor. After a good run the motor and 30 amp Turnigy Plush ESC were just warm.
Much more power than I need, but this battery will solve the balance problems without nose weight.

Quote:
I will be interested to see the painting results. I am still a couple of weeks away from that and haven't quite made up my mind as to what to use.
Priming has begun; watch this space.

Jim.
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Nov 06, 2019, 10:33 PM
Space Coast USA
hoppy's Avatar
Thread OP
No problem Jim, interesting posts. Looking forward to finished product and flight video.
Nov 07, 2019, 12:15 AM
Foam is where the heart is
brett.c's Avatar
Quote:
Originally Posted by Jim.Thompson
Yes Brett; 35 sq.dm..
That gives a WCL of just 6, right down in the trainer area, so she will be a floater.

I tried a bit of the Gorilla glue on my cowl today. Mixed it 50/50, the same is I do with interior PVA.
It seemed quite thick compared. More creamy than milky.
Went ahead anyway. It gets quite tacky and tends to dry a lot faster. This was handy for this curvey piece because I had no problem getting the folds to stick down, which was always a problem with the other stuff. Not sure how this will go on the wings. I may have to thin it some more.
The end result was quite good and was ready for sanding in just a couple of hours.
Nov 07, 2019, 10:53 PM
Foam is where the heart is
brett.c's Avatar
I watered down the Gorilla glue some more and covered the wings.
IMO this glue dries a little too fast. It is touted as fast drying, which is handy if you are gluing two bits of wood together but not so much for our purpose.
It was easier covering things like the wing tips where the fast drying nature works in your favour, however for larger surfaces you don't get much time to work out the bubble etc. Though it did pull up nice and tight and I have very few wrinkles to sand out.

Weight was 242grams uncovered and 295grams covered, about a 20% increase, which is acceptable.
Nov 08, 2019, 12:41 AM
Entropy is happening!
Jim.Thompson's Avatar

Paint on.


My model has now been sprayed with the final colours. Acrylic lacquer.
I will assemble it tomorrow..................or maybe, even late tonight.

Pictures pending.

Jim.
Nov 08, 2019, 03:22 AM
Entropy is happening!
Jim.Thompson's Avatar

First assembly after painting.


The model requires more weight in the nose than I anticipated. I now have a big 320 gram 4S x 3000 ma/hr battery right up the front and it balances at 33% MAC, which is where I will test fly it at.
AUW is vastly over the estimate at aroun1550 grams with the servos that are not in the picture.
However, that still works out to a cubed loading of 7.2.
And a wing loading of around 42 g/sq.dm.
Not too bad.

My appraisal of the covering system:

It is a viable, cheap and effective way to cover a model. I will possibly do it again. However, the finishing and preparation for painting requires a lot of work and heavy filler etc. I used "Q" cells thickened acrylic primer spread onto low areas, sanded and repeated as required.

In future, I will revert back to my composite techniques, but only because I have everything required in stock and I am very experienced in that method.

This is a good thread and I'm glad I had a go at it.
I will post details about the flight test which will possibly be in a weeks time, all things going to plan.
Thanks Hoppy and all other respondents.

Jim.
Nov 08, 2019, 06:30 AM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
I'm about to start attaching control horns. I used coffee filters and 50/50 TBII and water. I'm looking at gluing them on, they have a section underneath where you cut a slot and it goes into the control surface. Interested in whether or not it makes sense to cut away the covering material to balsa for better adhesion; I'm not sure that would help, guess it depends on how well the covering is attached to the balsa. Also interested in what glue to use; TBII takes a long time to dry but is really good, I'm leaning towards that.

Thx.
Nov 08, 2019, 06:46 AM
Registered User
Quote:
Originally Posted by brett.c
I watered down the Gorilla glue some more and covered the wings.
IMO this glue dries a little too fast. It is touted as fast drying, which is handy if you are gluing two bits of wood together but not so much for our purpose.
It was easier covering things like the wing tips where the fast drying nature works in your favour, however for larger surfaces you don't get much time to work out the bubble etc. Though it did pull up nice and tight and I have very few wrinkles to sand out.

Weight was 242grams uncovered and 295grams covered, about a 20% increase, which is acceptable.
Wow, pretty lightweight. Is it newspaper or kraftpaper ? It looks like Kraftpaper.
Nov 08, 2019, 03:42 PM
Entropy is happening!
Jim.Thompson's Avatar

Problem.


I have struck a problem with one of the wings on the model I've covered this way.
One section of the surface skin of one wing has distorted very much.
I suspect that it was the solvent out of the paint primer/filler that bled through the paper/glue covering and attacked the foam.
It would involve some complex surgery to repair, which is not out of the question...............
Building another set of wings is a major undertaking, as it has a full "I" beam shear web and cap main spar and pocket hinges. Of course, the ailerons would be salvageable for a replacement.
All would have been fine had I sticked to water based systems throughout.
I'll take a picture later.

Perhaps I will see if it flies ok before doing anything about it. But knowing me, it will haunt me until I do something about it.

Jim.
Nov 08, 2019, 05:38 PM
Foam is where the heart is
brett.c's Avatar
Quote:
Originally Posted by stereodreieck86
Wow, pretty lightweight. Is it newspaper or kraftpaper ? It looks like Kraftpaper.
Not sure what it is called. I just picked it up from my local office supplier. I can tell you that it is .07mm thick, which is thinner than our newsprint.
Nov 08, 2019, 05:48 PM
Foam is where the heart is
brett.c's Avatar
Quote:
Originally Posted by Jim.Thompson
All would have been fine had I sticked to water based systems throughout.
That's what I concerned about. Had it happen to wbpu/tissue covered build once, but only in a small area when I went a little heavy with the paint.

Give it a go mate, you might be surprised at how much you can trim it out. A guy in my club has a slow stick that is so bent and twisted that you would think there is no way this thing would fly, and does, and well.
Nov 08, 2019, 06:17 PM
Entropy is happening!
Jim.Thompson's Avatar
Quote:
Originally Posted by brett.c
.....................
Give it a go mate, you might be surprised at how much you can trim it ou....................
I planned to Brett; I decided that this morning after looking at again. Things always look worse at midnight (or later!).
It would not surprise me if this did not affect the flight performance; it is just niggling.............
Nov 09, 2019, 02:52 PM
Registered User
Quote:
Not sure what it is called. I just picked it up from my local office supplier. I can tell you that it is .07mm thick, which is thinner than our newsprint.
I tried Japanesepaper and with Ponal Express Glue on my Shinden build (see link below), the result is surprisingly strong and fun to work with; no sticky fingers, no smell and its a fast method.

https://www.rcgroups.com/forums/show...saveing-weight


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