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JU87 Stuka

80" from John carpenter plans

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andy watson11/01/2009 23:19:00
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Well.............

The paint is still wet on the DVII (literally) and I am really diving into the deep end!

I have bought plans for a JU87D.  They cost £15.  These were published in RCM&E and are a perfect size for my Saito 1.20 4 stroke.  There are a couple of issues even at this stage.  I love the brutal ugliness of the Stuka, but I think either the A or B has this more than the D.  I have looked without sucess for B plans in this size, but I can only find 60" (too small) or the famous 100" Zirolli plans (too big).

So, I will either:

  1. Find an interesting colour scheme/story behind a D
  2. Convert the plans to a B

At this moment either option is open to me.  #2 is obviously the more difficult option, but might bring other advantages later, as I think it will be easy to hide an inverted engine. 

The good news is I have been in contact with the designer- the internet really is a fantastic tool!  This obviously means he will be in for a snowstorm of messages every time I get stuck, but it will be interesting to see what he thinks as I progress!  As this is my first plan build (and only my second ever ) I don't expect this to run smoothly- but then again it's only balsa.  It's easy enough to grow more!  So please- as much help as possible- it got me through the DVII build and made for a better end result! 

The first job is to read about the stuka, and it is a very interesting plane.  I have a sneaky feeling it won't end up a German one.  They served everywhere- from the Spanish civil war to Japan!  Not bad for a plane that was just about obselete before the war started.  This means there is a fantastic range of colour schemes and options available.

So- initial thoughts about the plans.

  • They look to be excellent- although I haven't really look at many others for comparison!   There are 4 big sheets and the printing looks very good.  The plans are very clear from a printing point of view. 
  • It would have been nice to have the parts on a seperate sheet that I could have cut out more easily.  I think the scanner/photocopier will be getting some hammer over the coming months.  
  • I don't know how common it is, but a shopping list of required balsa would be a big help.  I will almost certainly buy too much of something, and not enough of other bits.  Fortunately I have one of the bigger balsa suppliers about 20 miles away.  I will have to try work out what I need from the plans- no easy task in itself and my first job.
  • According to John there is a build article about these plans.  Now David has said he is happy to copy it and send it to me if I can find out which issue it was, but it would have been nice to have it included with the plan.  Plans aren't exactly price sensitive- you want a certain plane in a certain size, you don't want to spend £X on a plan then build what you can buy!  So if it means adding a quid to the price, then I think it would be well worth it.
Dave S.12/01/2009 06:04:00
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Details of the magazine with the build article posted to your other thread.
David Williams 212/01/2009 16:02:00
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What about this as A colour scheme ? Captured in 1942 and evaluated by the RAF . Not many seen flying round !

Edited By Biggles' Elder Brother - Moderator on 18/02/2011 18:17:13

andy watson12/01/2009 17:28:00
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Ha ha- that's quite funny.

I wonder if I can find any more details............

andy watson17/01/2009 16:26:07
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Looks like a post or 2 has vanished with the move.

I did find a captioned photo of the stuka above.  Apparantly squadron 112 captured it, and the CO decided to use it for "beer runs".  Can't remember the link as it was a while ago.

I have spent the last week scanning bits of the plans and printing them out. 

Firstly there is a knack to scanning on an A4 scanner.  I didn't have the knack when I did the wings, so there was a lot of repeating what I had done.  Also the plans have already got a "worn" look from extra creases and stuff.  When I did the fuselage formers and other bits and pieces I managed to do it better- less wasted time and less crumpling!

Fortunately I had read up on the difficulties of doing this, and was prepared to have to mess around with settings to ensure the print/scan was the same size as the original.  I carefully measured every piece and redid any that didn't match exactly.  I did find that making sure the scanner lid was firmly in place helped. 

So I now have a copy of all the shaped bits.  I have trimmed round them and am now using them to work out how much wood I need.

andy watson22/01/2009 20:36:08
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1942 forum posts
20 photos
Well, I am in a bit of a dilemma.
 
At work I have access to a CNC machine.  This means I can teach myself CAD and then draw all the bits into the program and use the machine to cut them perfectly, or I can cut them by hand.
 
I'm not sure which would be fastest/easiest!
andy watson22/01/2009 20:40:33
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1942 forum posts
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The wood order has gone in!
 
Ordered it from SLEC- they are about the same on price as other balsa retailers but once a 20% discount for spending more than £50 on wood kicks in they are cheaper.  I also think they have the widest range, and have heard very good things about the quality of the wood they supply.
 
No doubt I have missed some bits.  I had to phone them forst thing to tell them I had missed some 1/4"*1/4"*48" spars off because when I was carefully making the list I forgot I had a top and bottom main spar on the wings!
 
Anyway- here is the list- should be enough to do it all!
 
3BW31                 Balsa Sheet 1.6 x 76 x 915mm           3        £0.72        £2.16
                      (1/16 x 3 x 36")                                                  
                       : Medium                                                          

3BW41M                Balsa Sheet 1.6 X 102 X 915mm          3        £0.84        £2.52
                      (1/16 x 4 x 36")                                                  
                       : Medium                                                          

3BW42M                Balsa Sheet 2.4 x 102 x 915mm         33        £0.98       £32.34
                      (3/32 x 4 x 36")                                                  
                       : Medium                                                          

3BW47M                Balsa Sheet 9.5 x 102 x 915mm          1        £2.18        £2.18
                      (3/8 x 4 x 36)                                                    
                       : Soft                                                            

L250M                 Balsa Strip 5.0 x 5.0 x 915mm          1        £0.23        £0.23
                      (3/16 x 3/16 x 36")                                                

L251M                 Balsa Strip 5.0 x 6.5 x 915mm          1        £0.25        £0.25
                      (3/16 x 1/4 x 36")                                                

L260M                 Balsa Strip 6.5 x 6.5 x 915mm          9        £0.26        £2.34
                      (1/4 x 1/4 x 36")                                                  

L2604M                Balsa Strip 6.5 x 6.5 x                4        £0.53        £2.12 
                      1220mm (1/4 x 1/4 x 48")                 &nb
andy watson22/01/2009 20:41:35
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1942 forum posts
20 photos
Hmm- missed a load off..........
 
L262M                 Balsa Strip 6.5 x 12.5 x               1        £0.42        £0.42
                      915mm (1/4 x 1/2 x 36")                                            

L281M                 Balsa Strip 12.5 x 25.0 x              4        £1.04        £4.16
                      915mm (1/2 x 1 x 36")                                              

PW101M                0.4 x 300 x 300mm (1/64 12" x          1        £4.18        £4.18
                      12")                                                              

PW203M                0.8 x 300 x 900mm (1/32 12" x          1        £7.20        £7.20
                      36")                                                              
                      Wood Value over £50 - 20%                                  -£17.70
                      Discount                                                          

PW302M                1.5 x 300 x 600mm (1/16 12" x          1        £3.40        £3.40
                      24")                                                              

PW1403M               3.0 x 300 x 900mm (1/8 12" x           1        £3.31        £3.31
                      36")                                                              

PW501M                6.0 x 300 x 300mm (1/4 12" x           1        £2.00        £2.00
                      12")                                                              

HD4M                  Hardwood Dowel 6.0 x 915mm             1        £0.44        £0.44
                      (1/4 x 36")                                                        

EB07M                 Beech 12.5 x 19.0 x 305mm              2        £0.66        £1.32
                      (1/2 x 3/4 x 12")                                                  

3SP240M               Spruce Strip 3.2 x 3.2 x               1        £0.25        £0.25
                      915mm (1/8 x 1/8 x 36")                                            

SL115-R               Closed loop Wire 3 mtrs                1        £2.00        £2.00

W15     &nbs
andy watson22/01/2009 20:42:10
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1942 forum posts
20 photos
and more missed!
 
W15                   16 swg. x 36" (1.60mm x 915mm          1        £0.71        £0.71
                      )                                                                  

W13                   12 swg. x 36" (2.65mm x 915mm          1        £1.20        £1.20
                      )                                                                  

W081                  (4") 100mm Grey Hub Wheel              2        £2.70        £5.40

W021                  (2") 44mm Grey Hub Wheel               1        £1.23        £1.23

L120M                 Balsa Block 25.0 x 25.0 x              1        £1.62        £1.62
                      915mm (1 x 1 x 36")                                                

L124M                 Balsa Block 25.0 x 75.0 x              1        £3.98        £3.98
                      915mm (1 x 3 x 36)                                                

L143M                 Balsa Block 50.0 x 100.0 x             1       £12.54       £12.54
                      915mm (2 x 4 x 36")                                                

L271M                 Balsa Strip 9.5 x 12.5 x               1        £0.61        £0.61
                      915mm (3/8 x 1/2 x 36")                                            

SL031-R               Metal Razor Plane                      1        £3.50        £3.50

SL31A-S               Spare Razor Plane Blades               1        £1.00        £1.00
andy watson22/01/2009 20:43:16
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1942 forum posts
20 photos
That's the lot. 
 
Couple of other bits and pieces in there too.
 
Total price including delivery & discount: £94.85
andy watson01/02/2009 18:11:23
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1942 forum posts
20 photos
Well- here's what about a hundred quids worth of balsa looks like:
 

I am actually 5 sheets down on what I ordered, but SLEC have promised to send it on.  I'm hoping they haven't been very efficient because I have now realised I forgot some other bits and I might be able to sneak them in for free postage! 
 
Anyway, since the last update I have spent a lot of time copying bits that I needed 2 of.  I am so glad I am not doing this 10 years ago, where I would have been using carbon paper or tracing paper.  I cut out the rest of the bits, and have glued the paper copies of the parts onto the sheet balsa (except the fuselage formers which need 1/8" sheet balsa- which is what I forgot!).
 

andy watson01/02/2009 18:15:22
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1942 forum posts
20 photos
3 weeks since the plans arrived.
Just for curiosities sake I looked back at the progress I had made after 3 weeks of the DVII kit build!
 
I had built just about all the wooden structure- wings, tail, fuselage, the lot!  With this build I have managed to glue some paper to some wood!
Djay03/02/2009 09:33:11
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543 forum posts
445 photos
Hi Andy.
good to see your are building a different variety of aircraft.
just please get your D7 flying, the suspence is killing me.
My D7 is still flying well, and I have just built the Baronette kit from flair.
I have a Zirolli stuka awaiting build, and I was contemplating yesterday whether to start it or not. So your build will have to influence me.
I have all the wood, spent about 300 pounds 3 years ago on it all, and I got a laser cut kit of all the ply parts and other cut out parts from the states. It worked out less then 1 sheet of ply in UK.
The only thing stopping me, is the size of it, here in Dubai it is only a transit country, and we may end up moving villas quite regularly, and the non availability of the fibreglass and resin, and paints to cover it.
It is a real pain to source them.
Good luck with the build.
Darryl
andy watson08/02/2009 22:21:16
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1942 forum posts
20 photos
Well Djay, maybe you could just sell me your plane collection- seems we have similar tastes!
 
That last week or 2 has been a case of patiently cutting out all those bits to make what I guess could be described as a short kit.  The balsa sections were easy.  The ply sections were a pain- fortunately the school has a bench fret saw, and an hour or 2 with that helped immensely.
 


And now it's time to start actually gluing!
 
And I immediately run into a problem.
 
The centre section of the wing is based around 2 plywood spars that are angled to give the correct geometry.  When I put them over the plan everything looked OK, but when I dry fitted the ribs in place I noticed something strange.  There is a gap between the main spar and the leading edge (obviously).  This tapers out to the tip (giving the wing a very slight swept back leading edge, but in the centre this is a constant until the 4th rib.  Unfortunately looking at my ribs there is a decreasing gap between the front and the slot for the spar on the first 4.
 
Now I am aware of the number of times I thought the DVII was wrong, and I am aware of the number of times it turned out to be me!  Anyway, I e-mailed John and he couldn't explain it either!  I think I will have to make them all constant, but for now I have done the easy option, and started on the tail!
andy watson08/02/2009 22:31:16
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1942 forum posts
20 photos
From tiny acorns a stuka is built!
 

The tail causes it's own problems, but initially at least these are due to my inexperience.
 
The ribs are curved on both sides- rather than the flat cross section I built before.  This means you cannot simply pin it to the board and build.  I cut the ribs in half, as suggested, and glued the top half in place, but had to put a ruler under the half ribs to lift them to their correct place.

Notice the tail ribs halves above the assembly.  They are the bottom halves of the ribs that have been fixed in place.  I thought it best to ensure the top and bottom of the same rib were reunited in the tail to get the best fit.  Once the top halves were glued in, I took it off the board, turned it over and glued the bottom pieces in place.  My precaution of matching top and bottom seems like a wise one- I tried to glue one piece the wrong way round, and it didn't fit tightly- and so was immediately noticeable.
andy watson08/02/2009 22:47:42
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1942 forum posts
20 photos
Problems with plans.........continued........
 
Look closely at the following picture:
 

The important part is the middle section- the tail rib profile, and the section of the plan I used to copy and make the ribs.  The sheeting top and bottom is 1/16" balsa.  The leading edge is made from 3/16" sanded to profile.  If my maths is correct, then the 2 butted 1/16th sheets will leave a space of 1/16" for the front of the rib, but by simply looking at the plan you can see the front of the rib is thicker than the sheet above or below.  So my ribs don't fit neatly into the LE (or TE) nice and neatly like the picture.  They do on the top where I measured, but then stick out underneath.  When I measured the thickness of the LE on the plan it was about 5/16".
 
My plan is to build up the LE & TE to match the ribs (+1/8"), and shape from there.  I would rather do that than sand/cut back all 18 ribs; and I would rather the tail was too thick than too thin!
 
John has warned me there is always a degree of "cutting to fit", so I better get used to this!
andy watson16/02/2009 14:58:15
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1942 forum posts
20 photos
One thing I should have mentioned a few days ago is the missing wood from the order turned up promptly.  I don't mind companies that make mistakes occasionally, as long as they make an effort to put them right, so well done SLEC.
 
Just whilst I am on about SLEC, I bought a little razor plane with the wood, and it's been brilliant to use.  Makes large areas of shaping much easier than sanding it down, and much safer than trying to shave it with a modelling knife.  Well worth the money.
 
 

Anyway, on with the build and I added a slither of 1/16 to the leading and trailing edge as I described above.  This allowed the sheeting to go on as described.  Sorry, but I thought I had taken some photos of this but apparantly I forgot!
 
Then I sheeted one side of the tail, and left it to dry (I am trying to use aliphatic glue during this build as it's supposed to be stronger and less brittle than cyano.  Once the glue was dried I noticed a distinct warp in the wood- I am guessing the drying glue pulled it round.  The only option was to wait till I was ready to sheet the other side and hope it pulls it back straight.
 
Inside the tail plane are a couple of reinforcing blocks for hinges, and a couple of ply reinforcements for the tail strut (it's a D, so a single strut).  Then on with the top sheet.  This time as well as clamping the sheet in place I weighted it down to make sure it was straight- I didn't want to reinforce the warp!  When dry it had indeed pulled itself back straight, which was a relief. 
andy watson16/02/2009 15:06:11
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1942 forum posts
20 photos
So the tail plane is now a sealed unit- it feels extremely strong, and is incredibly light.  The sheeting gives it extra strength, and I am sure it is stronger and lighter than the built up tail on the DVII.  One of the things I really enjoy about building is seeing how the design of the structure works.
 
So out with the trusty plane and sandpaper, and the leading edge is rounded off neatly.  I noticed that the clamps seem a bit firm on the thin 1/16" sheeting, and have dented it, so a little filler will be needed there later.  In future I will clamp a piece of wood between the clamp jaw and the balsa to protect it. 
 
The trailing edge is given a concave curve.  I did this by hacking away some of the centre wood with a knife, then using a small round and half round file I have.  I had to remove the handles, but they worked well, if slowly.  Once the basic shape was there I moved onto 80 sandpaper wrapped around one of the files and it didn't take long at all.
 


Note I have marked the tail top & bottom.  This is to make sure when I assemble it I place it the right way round so the plywood tail strut supports are where they are supposed to be.  Because they are inside it's now impossible to tell.!
andy watson16/02/2009 15:11:48
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1942 forum posts
20 photos
I thought the elevator halves would be difficult, but they turned out to be very easy.
 
Cut a 1 5/8" strip off the 3/8" balsa sheet and cut the elevator shape out, quick sand then rub/plane a curved front edge.  Mark out a line down the middle of the trailing edge thickness, and join it up to the start of the curve.  Get planing!
 
The tapering elevators emerged from the block very easily and look great- and there was me wondering if I should buy triangular strip instead!
 


Now the elevators fit inside the concave rear edge of the tail plane and will hide the hinges and look super smooth!

I have actually deepened the concave edge slightly since taking the photo.
andy watson16/02/2009 21:52:22
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1942 forum posts
20 photos
I know it seems a bit random, but I have done the tail plane struts. 
 
There was a good reason for this- they were right next to the tail plane on the plans!
 
They are of an interesting construction- 2 1/8" balsa sheets triangles with a strip of 1/16" ply running through the centre.  What make is interesting is the ply doesn't form the full centre layer, just a strip through the middle, with 1/16" balsa forming the edges.  If it were me I would have just used ply the full width- but there is probably a reason for it that's beyond me.  I can't see weight saving alone would be the reason as the difference will be minimal.
 

Here is the 1/16" ply centre strut being glued to the balsa outer layer.
 

And here the (rough) 1/16" balsa sheets are glued alongside the ply centre strip.  A second 1/8" balsa triangle sandwiches the whole lot together.
 
 
A little shaving and sanding, and here's the result.


 

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