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Old Oct 09, 2012, 09:01 AM
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Got 4 more hours into it last night.

Stations 1-23
Total Weight:3 oz
This is leaving me 11oz more for the other 20+ stations and wings and glass.
Not to sure my 14 oz goal for an empty airframe is gonna be doable.

Man look at the size differences. I tried to scale mine to be on scale with the a-10. There is no way fsa rules would allow me to do it. May be an inlet at 70% FSA, but those don't work well and im not cutting cheater holes in this one
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Old Oct 09, 2012, 12:04 PM
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D-Fast nice work. Nice and clean work in fact. When I start cutting the works space quickly fills with bits and pieces.

Actually reading the posts which way did you decide to go? a twin 64mm or a single 90mm? Were you able to get space for the landing gear in the belly?
After looking at the forms for a while EDF access port could be the landing gear mounts itself. I.e. open the landing gear doors, and create a single mount for the retracts to mount to. That same retract mount be removable to access the EDF if its Bifurcated.

At first when you said 1" slices I started wondering why go through that much trouble with many many cuts since several sections are just straight lines. I had in mind to cut longer sections where I could; along with cutting out the fuse, hollowing where I could. Then from the internal left over inner, cut it into many slices to work out the turns of the duct.

But then I starting thinking there is a bit of an advantage to the slices. If done with epoxy or similar, may be even with 2 oz glass, each becomes like a bulkhead harder than the foam around it that can be connected internally with glass/kevlar/CF stingers the length of the internal fuse.
At least in my imaginations it sounds like a light alternative to a thinner outer wall cut.

Will your wings be removable in some way?

I don't think I'd go with a built up wings though. Foam core balsa skins even without glass is plenty strong for this size.

Are you adding in the Fowler Flaps? Did the Frogfoot have leading edge slats of some kind. I nver got around to confirming and I haven't found a confirmed reference if its like the hard LE of the A-10.

Oh and to match scale tell your brother he has to go out and get the LX A-10 twin 70. They should have made that Dynam/blizt/Starmax 64 just a little bigger.
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Old Oct 09, 2012, 01:13 PM
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This is the 2x64 build. I rushed the start on this one. I didn't get to incorporating fully the re tracts into cad. After cutting I can clearly see I don't have the depth needed.

Now onto the 1in stations. I beg to differ. If I show you a side profile with 2inch cuts you'll see lots of voids or areas that don't get filled which we end up filling sanding filling sanding, I'm wanted nice contours without all that.
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Old Oct 09, 2012, 01:50 PM
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+1 I agree, the more stations, the better detail. Whwn you cut the stations, did you put #1 on front of foam and #2 on the backside. Kind of a leap frog metiond. 1-2, 2-3, 3-4, etc? I know more work , but worth it.
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Old Oct 09, 2012, 02:00 PM
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Cooler, yes I did. To many pieces, to easy to loose track. Its a bit of a paon lining them all up. When I update the plans I may run 2 carbon rods down the bottom fus to help keep things all in line when gluing. On this build I will use 1 layup of 1/4 oz glass on top then a cross woven 2 layer lay up on the bottom using 1/2oz and topping it with 1/4oz. This should give me the strength I'm looking for.
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Old Oct 09, 2012, 02:47 PM
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I don't disagree about how it affords detail. And around the intake to exhaust sections it does get curvaceous. I have two plastic models and the Sukhoi drawing where they have the sectional contour changes about the fuse in 9 sections, again excluding the contours of the engine/wing section.

But skipping all that the other advantage why its sounds like a good idea is the bulk head idea......

Something else you mentioned was the elevators. These have a Stab/elevator for pitch control where the stab is adjustable to trim different flight profiles. At least thats what two of the guys who said they flew it advised how it operates.

I've forgotten his name or I'd ask him regarding the wings LE.

Either way details are good. So I'm gonna try to use that detail to my advantage as you have for detail as well as for strength.
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Old Oct 09, 2012, 03:19 PM
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All you have to do is look at the 2in cuts on my canopy area of the yf23 im doing and you will see the voids compared to the 1inch area's of D's and you can see a big difference. 1 inch on those area's is the way to go.
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Old Oct 09, 2012, 03:56 PM
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@Uncle, if thats not all glued up yet. Ask and you shall receive.

@Max, not sure on the removable wing yet. I kind of just jumped into the build,gonna wing it so to speak.
With half arsed plans, heck ive started cutting before i even have my full sheet completed.
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Old Oct 09, 2012, 04:34 PM
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Oh I agree. Podium Jets Mitzu did his T-50 PakFa in 100mm sections unless the lines curved abruptly. Because even that model having stronger curves than the 25/39, it still only took a little sanding to get it true.
But when we asked if he could accommodate the landing gear compartment, he couldn't detail the curve around where the wheel would stow.

It was from that problem that I realized cut out the internal section to adequate wall thickness and use the internal core, cut up into shorter sections to start adding detail.
But if the outside panel lines are all straight the cuts don't have to be as detailed. The cockpit of the SU-39, below the canopy is straight panel but above has the curves. So the canopy I formed in thinner sections where as the lower is made up of 5 sections from the nose to the back of the gun turret.

Nothing wrong with the detailed sections though as it adds strength in the way of bulk heads. The bulk heads can allow for a thinner wall. So I'm redoing mine to smaller sections as he did in certain areas.
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Old Oct 09, 2012, 04:41 PM
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Quote:
Originally Posted by D_FAST View Post
...@Max, not sure on the removable wing yet. I kind of just jumped into the build,gonna wing it so to speak.
With half arsed plans, heck ive started cutting before i even have my full sheet completed.
Hey, I've worked the same way and the ideas come as I go along. Your ahead of me so I'm kind of using your work space to hash out my approach while I'm still working on other projects.
Criticism offers little in the imagination vs reality. I'm still imagining where you're actually making. And you can make changes each time you build one.
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Old Oct 09, 2012, 04:51 PM
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Originally Posted by D_FAST View Post
@Uncle, if thats not all glued up yet. Ask and you shall receive.

@Max, not sure on the removable wing yet. I kind of just jumped into the build,gonna wing it so to speak.
With half arsed plans, heck ive started cutting before i even have my full sheet completed.
HA HA LOL don't worry about I was just showing an example. The canopy is the only area where when put on the side view you will see where it shrinks of the side view in those 4 or so area's. Its allready glued, But I was thinking of cutting them out, then I said its not too bad where I cannot add a bit of filler or shrink it a bit when sanding The average guy would not know the difference unless it was over the plan. Maybe after Im done and if you decide to clean up the plan you could do it then. But Im fine and very happy with the turn out of it.
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Old Oct 09, 2012, 07:49 PM
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spent littlle more time trying to come up with the wing,i like the way Jumpy did his removable wing so im trying to mimic it to a point.

I want something light,i was thinking 3mm depron skin,balsa TE,Balsa LE, Inner,mid,outer rib roots lite ply, 6mm depron ribs in between,and the cradle system that jumpy used in his build

This will be my first built up wing and very much a work inprogress, so any help, critz, is very much appreciated.
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Old Oct 09, 2012, 07:55 PM
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Originally Posted by BillO View Post
Very nice drawings! I'm in the CAD learning stage, so I was wondering if you would mind sharing your workflow for the fuse. Did you have cross sections, trace them, then skin it somehow? Or draw it some other way? I've been doing a lot of searching as well and haven't been able to find much in the way of details.

Also, you might try sending a PM to the guy that does those fantastic Sketchup built-up airframes -- the Rafale, L-39, etc. Clearly he is an expert on built-up construction.

I bet the SU-25 will be a great flyer!
You sure are a prolific designer, DFast. I appreciate your willingness to share.

I too am in the same boat as Bill-o; ie. I'm self taught & struggle some with 3D CAD. You probably mentioned elsewhere which CAD s/w pkgs you use; but can you mention again which ones they are?

BTW, I started with DesignCAD; not sure how it compares with your pkgs.

TIA!

Phil
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Old Oct 09, 2012, 07:59 PM
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Originally Posted by PhilLin View Post
You sure are a prolific designer, DFast. I appreciate your willingness to share.

I too am in the same boat as Bill-o; ie. I'm self taught & struggle some with 3D CAD. You probably mentioned elsewhere which CAD s/w pkgs you use; but can you mention again which ones they are?

BTW, I started with DesignCAD; not sure how it compares with your pkgs.

TIA!

Phil

Thanks for the kind words...i mention a few here

http://www.rcgroups.com/forums/showp...9&postcount=13
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Old Oct 10, 2012, 02:25 AM
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few more hrs thrown at it.
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