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Old Jan 07, 2009, 07:23 PM
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Build Log
SAAB JAS 39C 1:10 scale for 70mm fan. Scratchbuild MAIDENED VIDEO INSIDE

Video here and on page 8

JAS 39 & Bobcat 25 maiden (6 min 36 sec)


Hi all,
This is my third attemp to get this model done. The previous model did have some designfaults, ie the intake and ducting .
Some facts about it...
*Scale, 1:10
*Wingspan ~80cm
*Lengt ~140cm
*For Minifan or equal, HW 609 or even midifan with some modifications.
*Moving canards
*All parts are designed with interlock. Almost the entire model can be put together w/o glue and then use CA glue afterwards.
* IŽve used the calculations from Greg Gallegos to calculate intake FSA. It will be easy to adapt it for every fan.

I have got all fuselagesections checked by SAAB the manufacturer for scale look and accurancy of the model,

The drawing is 90 % done. Material used is mainly balsa in 4 & 2 mm with carbonreinforcements.

FLYFLY retractcs will fit.

The only thing I need help with is to design the ducting. This is something I donŽt manage to do in my cad-program.

If there are any builders out there interested in building it together with me and share info and experiences in this thread you are very welcome. Hopefully weŽll have a couple of JAS flying around all over the world this summer...

Sincerely Marcus // Sweden

Links to my previous building threads:
Link to version 1 buildthread
Version 2, Discontinued due to design...
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Old Jan 08, 2009, 01:51 PM
Big gov never Works
St. Martin's Avatar
Skunk Water, Rhode Island
Joined Jul 2002
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Hi Marcus, I would love to take on a build with you. But, My table is very full, at the moment. I could make molds to fit a 70mm fan. Even a canopy. I'm no flow "guru". I design my ducting to use the desired % of FSA, then make a gradual volume to the fan. All mecanical, no CAD. But my ducting works, very well.

The ducting shown in the above pics has one concern. The transition from rectangle to semi-circular is too abrupt. There would be a drastic volume change there.

Good luck with your project. I'll keep watching. Nothing better than a good ol' wood build.

Fuzz
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Old Jan 08, 2009, 02:27 PM
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St Martin, You are welcome, IŽll keep you notified when the drawing is 100%. The ducting on the pictures is just the first sample to try out in Acad and get a feeling of thow the cut-outs in the fuse will look like.
//Marcus
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Old Jan 13, 2009, 06:12 AM
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I made some progress on the drawing yesterday. Mounted the FLYFLY retracts and made the final design of tje ducting. Pictures will come.
See ya // Marcus
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Old Jan 13, 2009, 06:26 AM
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Oh, I forgot to mention that IŽve been in contact with two companys who are able to laser cut all the parts for us in sweden...
//Marcus
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Old Jan 13, 2009, 08:45 AM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
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i think the fan is too far aft ...snd the inlet ducting should have a center fairing incorperated to let the air only see the rotor blades...looks good awsome project . sapac makes a big foam one for 70-90 mm fan.
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Old Jan 13, 2009, 11:49 AM
Claus at Area 52
clausxpf's Avatar
copenhagen Denmark
Joined May 2002
2,535 Posts
i do think this would be a tad better..
Claus at area 52
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Old Jan 13, 2009, 01:42 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
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Ah yes Claus that looks better ......and looks like something i did before
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Old Jan 13, 2009, 04:49 PM
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Sweden
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clausxpf, Irecon those pictures from my previous project IŽve tried to design it the same way but it is very hard to do.. Nice to see you in this thread to...
As you can see the fan is now in its right position. Intake is smoother and the transition to the fan is better. Canards is done, retracts is fitted together with the air tank.
I canŽt wait to start building, but first all the design must be complete and done.
The ducting has aprox 118% FSA from intake till it transits into round shape where it is 100% FSA.

Sincerely Marcus
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Old Jan 17, 2009, 04:58 AM
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Further progress... Yesterday a friend of mine came by and checked my drawing, especially the wing as he works as an aircraft engineer in the airforce. All OK
Building will start as sonn as I got all the parts from cnc-cutting.
Cheers // Marcus
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Old Jan 19, 2009, 04:40 AM
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Hi,
Yesterday I designed the linkage and structurel parts for the moving canards. I will use a hollow 5mm carbon rod as axle, supported by small ballbearings or a brasstube.
IŽll post pictures when IŽm back frpm work.
/Marcus
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Old Jan 21, 2009, 04:02 PM
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here are the plywood that holds the canardaxle and servo. You can also see the span of the canard.
More to come...
Marcus
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Old Jan 26, 2009, 02:36 AM
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This past weekend I finished the design of the inlet ducting. It will now be hotwire cut out of "foam" before I make a plug out og it and F/G it. Pictures will come.
//Marcus
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Old Jan 26, 2009, 05:18 AM
Speed Demon
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Antioch,CA,USA
Joined Dec 1999
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She's looking mighty spiffy Marcus! What do you anticipate the final weight to be?

I like your idea of being able to change fans. This model is going to be large enough to potentially use much more power than a typical MF480.
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Old Jan 26, 2009, 06:01 AM
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Hi GregG,
My previous build ended at~~1200g. I will try make it lighter this time. Better drawings means less extra building and material used. I want It to be as light as the Sapac 39 which is pretty much the same size but built all in foam.
Sincerely
Marcus
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