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SAAB J21R - Dual Combo


Christer A
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For this GB I thought long and hard on what to do. Should I finally start my ASJA B5 dive bomber, or go all in on a A32A Lansen in 1/48 to please my uncle?

After pondering long and hard, and looking at the stash and ongoing builds I came to the conclusion that dual booms should be a feature.

Also, earlier in the Autumn I found the attack version of J21R, with a full weapon assortment, to compliment the normal fighter version that I already had.

Cool!

Dual J21R it is.

 

The SAAB J21 was quite interesting project, but SAAB didn't really have the manpover to push the development of it during the war, due to full focus on the light and medium bomber B17 and B18.

Therefore, it entered service quite late in the war and at that time jet was coming into vogue. A planned J21B was studied, with a more blown canopy, better cooling performance and a few other changes, but at that time the the C FV Bengt Nordensköld (Chief of the Air Force) decided that all fighting aircraft (both bombers and fighters then) should be jet powered.

SAAB wasn't stupid and saw an opportunity to quickly adapt the J21 to jet propulsion, and claimed that it could be converted quickly and cheaply to "rea-drift". (at this time, it wasn't called jet in swedish, but rea which mean reactionpropulsion more or less)

 

As it always turns out, this conversion wasn't very fast, nor cheap and the end result wasn't stellar, but it did provide Flygvapnet with more jet aircraft and also paved the way for the much more advanced follow-on aircraft the J29 Tunnan and A32 Lansen.

 

There is lot more to write about J21R and I will do that later on, for now I'll focus on what I'll actually glue together, which is this!

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This is 2 old style Special Hobby kits, first Issued in 2011 so no terrible old. They did the J21A in between these two releases and in one fell swoop discarded the old Heller kit to collector status. Probably.

There are two common runners, like this

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Nice details and nice engraved panel lines

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No intake trunking or compressor face though!

 

The attack version got an extra runner, with a bomb and two different sets of rockets, both practice ones and the normal 12cm ones.

Thank you Special Hobby!

 

Resin wheels and guns sight are also provided

49374790326_875a0d7c37_o.jpg

 

Ok clear injection molded plastic

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Lots of tiny etched parts, and a sandwich instrument panel

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Two sets of decals of course, with excellent printing by Aviaprint

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To round it off, I have this book

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Which is filled with excellent photos, both period ones and also from the surviving museum examples.

 

This should be a lot of fun!

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welcome along Christer and great to see one of the more unusual and interesting aircraft in the build.

 

Thanks for the brief intro, I knew of these aircraft but not too much about them, so will be interested to hear more as the build progresses.

 

The attack version looks amazing with that line of rockets!

 

Good luck with the build, another one that I'll be following with real interest, and looking forward to seethe in the galley as well.

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It will be a pleasure to follow both these builds and take in all the historical information along the way. They look to be excellent kits and cannot wait to see how they scrub up in the hands of someone who obviously knows their local product. 
 

Cheers and best of luck.. Dave (owner of one ‘collector’ Heller J21A!). 

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Dang!

This thread is on the second page already.

Oh well.

I was sent an interesting picture from the F10 archives

49388250016_18e0bd3917_o.jpg

Here we can see the rocket-rack under evaluation. It appears to be the 10cm rockets that are loaded, and also note that the demarcation between olive green and grey-blue is soft.

 

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This model in my opinion has the following disadvantages:

 

- No anything in intake this kit, (but turbofan visible on real aircraft);

-  poor interior wheel bay.

 

For this model was also photoetched from two manufacturing.

 

B.R.

Serge

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I agree with you that the lack of intake and compressor blades are a real miss.

The wheels bays are quite ok to my eyes in this scale, especially since they're very small.

 

Let's get on with the build then!

I quickly separated the major parts and had a look:

49407656797_6ab1242e39_o.jpg

The fit is not stellar, but it's far from being bad.

I think that gluing the top wing to the fuselage first is the way to go here, just like with poor fitting Spitfire wings.

The ejection pin towers are plentiful though

49406975323_25c4bc3e1a_o.jpg

 

But I got a strange idea...RIVETS!

The real aircraft is quite smooth, but I wanted to have a go with my very unused riveting tools.

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A bad idea, since it was so time consuming.

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It took about 8 hours to do all this, and I need to redo quite a few places but the skin looks more interesting now. Not 100% realistic but it was a fun exercise.

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That’s such a lovely shaped aeroplane and from what photos I’ve come across all (most?) Swedish built aircraft were produced with the smoothest of airframe skins. The riveting will add interest as you say, so al the best with that. 
 

Cheers.. Dave 

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Thanks for the cheers guys! There will be bit more riveting later on, but I probably need to put them together first. I've very interested to see how it will look under a coat of primer...

 

Speaking about wheel wells:

49407454991_df66049d6d_o.jpg

The main ones are both simple and clever designed by Special hobby, especially for this scale. It will be a challenge to look up there once all struts and doors are in place!

 

While doing all riveting I used the plans found in Mikael Forslunds book above and I found a few things that were a bit fishy.

While the inner wing from the booms to the fuselage was ok, the span quite short!

It seems like a cm or so is missing in span! If the drawings are correct (which I haven't verified in any way) that's to say...

But what I did find, thet is wrong with the kit is the locations of the wing tanks. They should be 4-5 mm further forward.

Look here

49407455146_b751bc5b3e_o.jpg

Left side is according to the plans, right is according to the plastic.

In this case the plans and photos match up, so this means the all tanks shall be modified accordingly.

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On 1/20/2020 at 12:25 PM, Christer A said:

While doing all riveting I used the plans found in Mikael Forslunds book above and I found a few things that were a bit fishy.

While the inner wing from the booms to the fuselage was ok, the span quite short!

It seems like a cm or so is missing in span! If the drawings are correct (which I haven't verified in any way) that's to say...

 

I'm just guessing here, but I suspect SH used the 21R wingspan. That was 11.3 as opposed to the 21A with 11.6 meters.

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When comparing the under wing part to the J21A drawings, they match quite well, except for a few mm in span, so that makes a lot of sense.

However, when comparing against the J21R drawings...

49431167062_055a0dd0b6_o.jpg

There is a little larger difference in span again, but even more confusing is the boom spacing!

They were spot on compared to J21A but now they're too much outboards?

Something is wonky here...

The J21A drawings measure 161mm in span which is the same as 11600/72, so I'd guess that those are the accurate ones.

J21R should then be 4mm more narrow, but they aren't!

So that means that I can't trust the J21R drawings, and since the layout is good versus J21A I settle for that.

 

Right. Lets carry on.

 

 

 

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that's interesting and a worry!!

 

Not knowing this aircraft at all....when they added the jet engine did they have to do massive amounts of modifications? As play around with span, change boom widths?

 

When I originally read about this aircraft it just appeared to me they chopped out the rear 1/3 of the fuselage structure and rebuilt it to hold a jet engine. Of course with all new panelling was required around the engine etc.

 

If those drawing are to be believed there was lots of other work/modifications carried out, changing almost everything subtlety, so almost nothing but the front fuselage is common to the A model.

 

For a project like this one it doesn't sound right, so I think to your right to avoid those drawings.

 

Now iii it had been a Trumpeter model...well the drawings would definitely be right!! :D

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Hard to know what's right and what's wrong however it all seems pretty close whichever way you look at it. We are all different modellers and some things stand out for some while others will build on and ignore them. I'd prefer to see a well built model with an accurate paint scheme over something that might measure out a few millimetres short here or there. Either way its great to see you striving for accuracy which is always important and adds to the overall fun of the hobby. 

 

Cheers.. Dave  

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Well, my practical approach is to do nothing about it, and it will still be the "best" J21R I can build (or is available on the market)

 

But my engineering brain can't really let it go :)

I mean, the entire basis for the J21R was sold is as a minimal conversion of J21A in order for the SAAB designers to learn how to design and produce a rea aircraft (jet engines were called rea-motorer at this time, hence the designation R).

They thought they could keep 80% of the A and just install an new power egg. And then someone discovered that they need to move the stabilizer away from the jet efflux, another one thought it would be a great idea to install airbrakes, someone saw an opportunity to tweak the landing gear a bit so the aircraft has a different sit on the ground, and who's idea was to hide some emergency skis in the boom for the pilot to ski back to the base if he ejected in the wilds? 

So in the end, I think that only 50% is common with the A, even though the look very similar.

But this happens all the time when we engineer are allowed to tweak things...

 

It's not impossible to imagine that they kept the outer wings intact but then changed the centerpiece, since that's straight and they got rid of the leading edge radiators and they needed a new stabilizer in any way so the booms might've been moved just like that.

It's fun to speculate!😎

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41 minutes ago, Christer A said:

It's fun to speculate!

ask the Swedish AF museum, as they had to get SAAb to convert a J-21 in J-21R  for display, as detailed in the MMP book, or even ask SAAB?  

Interesting question.

The only other piston engined fighter converted a jet was the Yak-3 to Yak-15 BTW

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@Christer A you do know if you hadn't shown everyone that drawing you could have happily continued on and no one would have been the wiser! :D

 

Now you're stuck with an issue a lot of us have when building and finding something that's not quite right. 

 

a, leave it and it'll bug you forever

 

b, fix/correct it...........6 months later you may/might finally finish it! 

 

c, throw it on the shelf of doom and storm off muttering about Trumpeter!! :D

 

If it was 1/48th I'd say go for it, conversion work is much easier in that scale, 1/72nd....more fiddlily.

 

 

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Well, since I don't actually have any proof that the drawings are correct, I think option A & C are more likely. I mean, I will not let it bug me kit-wise, but there is always the risk that this project ends up on the shelf for 6 months or more, since I got the attention span of a common kitten.

 

I made a start on the cockpit though!

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Special Hobby wants me to bend 5 tiny levers and place them on this little console.

How about no?

I'll do one, add some plastic rod to it and call that a throttle and be done with it.

Like the lazy bugger I am...

Except for the throttle and instrument panel, the cockpits are constructed.

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It was duly primed and then painted green

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This green paint is the same as the outside color, which in this case were called W25. It was sort of a dark green , quite closely matched to FS34079.

Luckily, that is also known as Gunze 309 of which I had a pot available...

Nice.

While the paint is curing I started to look over my stash and found Tarangus J29A/B Tunnan!

Hmmmm...

F-8-Gul-J-Slutliga-2013-05-07-copy-1.jpg

Just add some decals from Moose Republic?

screenhunter_733-dec-28-23-48.jpg

 

Perhaps also some rockets and then I have all that I need for an Attack Tunnan!

 

 

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Hi Christer,

 

I am sure you know this already, but according to the Putnams book on Saab aircraft you are right about there only being about 50% commonality. They mention quite a few changes, including stiffening which might mean changes to the booms I guess, They mention changes to the tail including raising the elevator to avoid jet blast, increasing the inner wing chord and "sharpening" it whatever that means, moving the air brakes to the outer tailing edges, moving the wheels forward and higher, and steamlining the windscreen, I don't know how accurate this is but they say the wingspan of the J21RB was 11.37 metres compared with 11.60 metres for the A.

 

I would imagine changing the wings and booms would not be easy so I would just go with it as Dave said.

 

Cheers

 

Pete

 

 

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According to the MMP book 50% wasn't right either!

90% of all parts were different between A and R.

Exactly what drawings Special Hobby used when developing these models I don't know, but the general shape corresponds with how the R wing should look, so they're not way off.

Last year I hade a lot of work accurizing Classic Airframes d.h. Hornet, so I know that I can do modifications if I need/want to, but in this case the model is too fiddly to work with, and model itself does not in any way look wrong.

This is still the only injection molded J21R on the market and we will not see another one for a long time. 

 

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