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TOPIC: Profile SAAB J 39 Gripen for Rapier L-1 or L-2

Profile SAAB J 39 Gripen for Rapier L-1 or L-2 11 months 4 weeks ago #680

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Hi guys,

as you know, I have long admired Mark Digby's J 39C Gripen:



Mark has now finished his plan, and it was certainly worth the wait, for example:

And this is just the frontspiece! John writes:
"I too was impressed with his drawings, you may be surprised to know that the cover sheet is created from a rendering of a 3d model he spent many hours putting together. If you could see a view from the underside you would see it includes a fully rendered rapier motor where you can clearly read the L2 legend around the nose!

As a taster here is a lower-res copy of the wing templates:


and a close up of the fuselage side:


You can see how well Mark has thought things through - note the 3 degrees of positive incidence on the forward canard. The graphics are, I think you will agree, stunning.B)
The plan pack comes with extensive building instructions, for example:


If you would like copies of Mark's templates, just pop him an email at:
This email address is being protected from spambots. You need JavaScript enabled to view it.


John says they " look forward to forward to seeing how your prototype version progresses".:whistle:
but I don't think this will be until next year when I hope there will be quite a few Gripens (and Lansens, Drakens and Viggens making smoke trails in the air!

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Profile SAAB J 39 Gripen for Rapier L-1 or L-2 7 months 2 weeks ago #712

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Hi Guys,
I have finally been able to get started on the Gripen. Being a 'hemi-demi-semi profile model (it's compressed by 0.67 in width) construction is all-balsa, 3/32" sheet for the wings, 1/16" everything else. The fuselage is put together from light sheet sides with triangular edges and very light sheet top and bottom carved to shape. The thickness of the fuselage is sufficient to allow the Rapier to be hidden in a trough.
Here are the bits before covering:

and here are the all the parts after covering with paper:



The wings, tail and fin were easier than the fuselage, but did need some tidying up afterwards. The rudder and elevons are hinged:


Covering the fuselage, which is quite '3D' needed a lot of 'cut and paste' but the overall effect is not too bad. I was quite pleased with the tail pipe:



I agonised long about whether to add cockpit details, but, having moulded a canopy I decided to go ahead. Here is Sven in the office:


Next is gluing everything together. Watch this space!
The following user(s) said Thank You: ahmetcalfe

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Profile SAAB J 39 Gripen for Rapier L-1 or L-2 7 months 1 week ago #713

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Hi guys,
well, I've glued everything together, more or less in the right places, with the following result:







Not too bad, and the colours came up quite nicely with a quick spray of acrylic varnish. It weighs 36 grams (a bit less than I feared) so the wing loading is 5 oz/sq ft which is 'not too bad'. Happily, the CG is where Mark said it should be without nose weight.:cheer:

I'll give it a few hand launches the next warm calm day and see if its gonna be a goer. We will see.:S

Anybody else out there busy building? It's quite lonely here!
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Profile SAAB J 39 Gripen for Rapier L-1 or L-2 7 months 1 week ago #714

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Wow, that looks splendid, a great tribute to your skills. I presume that is 0.5 oz/sq ft though. How big is it? I'm guessing, 15" span and 20" long overall and about 100 wing area? Sounds light? It will go well, clean too.

Note added by Roger:
Wow, this is praise indeed from a master! But no, that is indeed '5oz/sq ft'.
It's a bit smaller than your estimate, Howard. The span is 8.8"; length 15.4". The wings are 36.4 sq in, 0.254 sq ft.
It weighs 36 g, 1.3 oz. So the wing loading is 1.3/0.254 = 5.1 oz sq/ft . Sorry about the mixed units, but it's what I'm used to!
:whistle:
I have flown Rapier models of 10 z/sqft so the Gripen should be OK, if a bit trcky to trim, and probably fast and twitchy. We shall see. :S

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Profile SAAB J 39 Gripen for Rapier L-1 or L-2 7 months 1 week ago #715

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Thanks for clearing that up, our thermal soarers used to be around 8 oz/sq ft so 5 oz should be sound. I think I was getting mixed up with grams/ sq/ins, but then I am a bit out of sorts at the moment.

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Profile SAAB J 39 Gripen for Rapier L-1 or L-2 1 month 5 days ago #735

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Hi guys,
It's been quiet on the forum of late, apart from reports about Old Warden meetings, and I haven't updated the 'Building' thread for (gulp!) some months. I have, though, been busy behind the scenes, sending off not a few kits and following some promising leads on 'neo Jetex' and a possible Rapier type motor analogue. Progress on these (if any) will be posted in another thread.

Because of all this I have only just got back to building. Below is progress with a new profile Gripen:



This is much more of a 'profile' model than my previous effort (see earlier postings in this thread) and is tissue covered rather than paper covered balsa. This is lighter and easier to apply, but obviously not as opaque. Still, it will look aok from a distance.

The new Lansen too is tissue over balsa and fles splendidly.



I'll post pictures of the completed Gripen in due course. Meanwhile, if anyone wants the Gripen templates, or even a 'part kit' please let me know. :)

Is anybody out there in building anything?
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