Noris - Bachem Ba349 Natter - Build Thread/Review

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More WOW! A forward bulkhead, a custom bass wood shoulder! A real Pro Build on this one. The good thing is that more weight on the nose can't hurt. The standard shoulder with some tape will work. The cone is heavy and on a E 12-4 drag separation is not a problem, and when mine started to nose down before ejection for a split second I was happy with the thought of a loosey goosey nose cone. Not that I was scared or anything like that. I knew my trifolds with the stock bungee cord were bad a$$ and could take anything a fast and level flying Natter could dish out.
 
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This one will have 45gm of nose weight (Noris suggest this) and I will be putting in a small bulkhead near the nose to hold the weight in place and provide a secure fitting for the nose ring/recovery harness.
You will probably need more than what Noris suggest. Partly because I wouldn't trust what Noris suggest (I've seen their V-1 go head over tail because the owner put in the "correct" nose weight) and partly because it's designed to take the German D7-3 motor. This motor, no longer in production, was designed to comply with German law which requires an explosives licence for any motor with more than 20g of propellant. The Estes D12 has 25g. So the D7-3 was created to give model rocket fliers in Germany something bigger than a C6 but without needing a licence. You'll be using the heavier D12 (as did that V-1, another reason why it went berserk). My own somewhat cruder, scratch-built Natter only became stable when I added enough nose weight to put the CG pretty close to the wing leading edge. (I don't know off-hand how much nose weight is in there, but it wouldn't help you anyway because the tail end is lighter due to only holding a C6-3.)

I am not a fan of the trifold mounts - I lost an Estes Long Tom in part due to failure of one of those. The nose flew away on its parachute never to be seen again while the body fell to earth in some scrub and without the chute we had no hope of spotting it.
Tri-fold mounts work fine for me. But I make them bigger than Estes so there is plenty of area grabbing hold of the body tube and more shock cord wound up inside them. Sometimes I smear epoxy over them to make them even tougher. In fact, since many of my scratch-built rockets have rolled paper nose cones with rolled paper shoulders, their shock cords often have a tri-fold mount at each end.
 
Yep, do what adrian says. Load it up and keep pushin' in clay and lead shot or BB's or whatever into the nose cone until that CG is near the leading edge of the wing. After that you can dig the clay out and weight it for fun. If the total weight is at or under the max recommended lift off weight for the D12-3 then press the button. Power and nose weight are your only friends. The tail and rockets on the back may pull the CP back a bit but their asymmetrical lay out is not helping much to make it fly straight. You might consider tabs to strengthen the attachment of the wings and tail. They will work with a good surface mount but will inevitably crack and break after every flight or bump from handling.
 
Well Leo suggested not less than 30gm - I was going to up that as noseweight to a bit higher and Noris reckons 45gm (which is unreliable given most of their dimensioning is wrong. I will have to wait and see how ass end heavy she is. Theres a lot of filler work to come which wont do the weight any favours.

ANYWAY - Onwards with my Iron Cross (with Oak Leaves, Swords, Diamonds and Filler Tube).......The build is a lot more advanced than the thread because finding time to take the pics, edit them and then post is quite hard at times.

Heres where the thread is....

Time to install the motor tube to the main body tube. This is relatively straightforward and on the Natter in some ways easier because the body tubes dont fit all that well and the result is the glue doesnt have that grab and hold factor that often makes this step a bit scary.
There are however issues - you need to have the plastic tail assembly to hand to make sure the motor tube goes far enough back to meet the rear of the plastic tail and not too far back - its got to be just right (like I didnt in fact as you will see later in the thread. I saw the potential for trouble and planned around it but the unexpected happened later on.

Anyway - the motoir tube was installed accurately using the tail part as a guide to get the depth of the motoor tube in the body tube correct, the body tube was pre-marked internally for the former/centreing ring locations on a dry fit and then glue was applied (one glue ring from the front of the tube and one from the back and then the motor tube was slid into place......and heres the next problem !!!
Because the centreing rings/formers are too loose (or the body tube is too big - take your pick) the tube doesnt want to form up well and need compressing onto the rings from the sides.

My firts go at this was using a press made from a bottle of water, some books and some condiment holders - this kind of worked but started to leave impressions in the tube and was also a bit too extreme so I moved to having the tube compressed between some books.

Firts pic shows the bottle based press - the second some of my current reading and a squished Natter :)

Ba349 Natter - 0027 Body Press 1.jpg

Ba349 Natter - 0028 Body Press 2.jpg
 
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If everything has worked out you get a perfactly shaped body tube - if not you get some mashed up paper. Luckily this one worked and the body tube after being left for a day or so was removed and found to be perfectly formed. Or at least as well formed as it could be given the fact the body tubes are a bit wonky to start with.

There were however ugly gaps in places as the centreing ring/formers are not perfectly shaped. These were filled in using two hits of aliphatic and some more gentle pressing using a collection of books including Commandant of Auschwitz and Nuremberg-Evil on Trial which seemed grimly appropriate. Lest you think me a crypto fascist I am a student of history and WW2 in particular and just picked up a mint set of 'The World at War' series, reduxed with ectra footage - its 26 hours of TV which has rather slowed down the Natter build - well the telly wont watch itself you know.


Pics show the final motor tube/body tube combo and the interior with the centreing ring/formers filled.

I dont have pics of the process but in fact during the early stages of drying the tail was left fitted to the tubes to make sure the motor tube stayed centred - careful you dont have any glue near the fitting before you do this - you wont want the tail glued down prematurely. I also had to sand a small bit off the formers because they didnt quite allow the motor tube to fit square with the tail assembly which would have left ugly gaps between the plastic tail and the main body tube.

Ba349 Natter - 0029 Body and Motor Tube.jpg

Ba349 Natter - 0041 Body Fillets.jpg
 
the world at war series was very well done! And so is this rocket! Keep up the good show
 
The real trick with this kit is to dry fit, test, dry fit again, and again. Lots of stuff to catch out the unwary or the hasty.

The tube rings do not fit the motor tube or the main body tube well and getting a good alignment with both AND the plastic tail cone is quite a chore. As you will see later despite all efforts, planning, thinking ahead, dry fitting etc something still rose up to catch me out. Luckily it wasnt fatal but it did mean a lot more work with filler.

I will do an update tomoz while partner is out doing their media stuff where the nose cone assembly is covered plus getting the tail cone on and a few fixes.
 
To hold the centering rings to the body tube I tacked with CA, making little spot welds to hold it in place and then hit it with yellow wood glue. The real problem with that is if you get it crooked it tends to stay crooked, especially if you are going by the directions.:( Yours looks real nice and straight!
 
Daddyisabar - thats why I decided to ignore instructions and go with puting the rings onto the motor tube - I just couldnt see any way of doing it reliably otherwise. Actually up close mine is a bit wonly because the centreing rings are not perfectly cut themselves and are slightly off centred/non symmetrical.

Anyway the bit that people may have been waiting for is next - getting the nose sorted out. As I already mentioned its a good thing with this kit to build all the sub assemblies first so while this build shows the nose cone being assembled now in reality it was put together in parrallel with the motor tube and the rear body. You kind of need all the sub assemblies as guages for the overall assembly and to give you the biggest heads up on potential trouble. In fact the nose cone wasnt finally completed until just after the motor tube/main body as it needed a tweak - the basic assembly was done and then it was held together with tape for a bit. I'll explain later as I go through the nose cone construction.

Firts up is to mark round the vac forms with a pen and then cut out with a harp knife. I decided to use the brand new X-Acto and it made a mess of one of the nose forms, the balde is too narrow on the knife so I swapped back to my standard craft knife to do the rest. Any really sharp knife will do.

After cutting out the forms were put flat onto some sandpaper and run around in circles gently until the edges were nice and true to a flat surface I usually use my Cermic hob or my glass dining room table for this.

Ba349 Natter - 0030 Nose Mouldings 1.jpg

Ba349 Natter - 0031 Nose Mouldings 2.jpg
 
Next up some scrap plastic from the vacuform was cut to thin strips and applied. I used a slightly wider strip for this than on the tail which turned out to be a good thing as you will see. The strip was applied almost the entire perimeter of one of the mouldings.
The strip in the tip of the nose was done seperately. These were all glued in using basic poly glue used for plastic kits and it was then left to dry for a day to make sure it was solid. I hate this kind of glue as its prone to making a real mess and it seems to get everywhere.

Once dry and test fitted it turned out the strip in the nose was a small problem and it had to be gently bent back a bit with pliers to stop it interefering with the opposite vacuform moulding.

Heres some pics of the moulding with the strip applied....

ps - Obviously you only do this to one moulding :)

Ba349 Natter - 0033 Nose Mouldings 4.jpg

Ba349 Natter - 0032 Nose Mouldings 3.jpg
 
Now at this point, suspecting trouble from a few earlier playing around with parts (and making rocket noises :) ) sessions I noticed that the nose cone MAY be too narrow to have a really good fit to the body tube. I was also tipped off by Daddyisabr that the shoulders on the nose were a bit thin. My dry fitting with the as yet unassembled main body tube/motor tube also suggested that the nose cone would be too narrow at its narrowest point to be a good fit for the main tube.

This is yet another reason why you need to keep dry fitting and testing the dimensions out with this kit. Simply having the nose cone held together with tape while I pressed the body tube together for a test fit showed this fault up. At a later stage it may have been awkward or ugly or both to make a correction.

I had considered making up a basswood/balsa rear end for the nose cone but then a happy thought occured to me - simply widen the nose cone by a few mil. This is how I did it.

Once the main body tube was glued together and in its final configuration I could modify the nose with some confidence of the final shape of the body tube. It turned out the nose would be approx 3-4mm short of a good fit. A dry run was done and the nose cone marked by pulling it apart slightly and marking with a pen where on the strip of plastic (flange) fitted earlier the nose would join up to be nice and tight.

It wasnt possible to cut a small strip of plastic to this thickness as it would mean a strip of plastic about 1.5mm - 2mm which was beyond my ability to cut accuratley so what I did was to place a plastic 'interefence' block on the half nose moulding opposite the one with the flange/strip of plastic added. This intereference block would stop the moulding closing together as the body tube end and thereby create a slightly wider nose cone at the body tube end. This would need to be filled later but I didn't see that as a major headache.

It sounds complicated but in fact its easy - the pics are worth a thousand words so take a look.

The first pic shows the interference block glued to the half nose moulding, second pic shows how it butts up againts the flange strip on the other moulding and the third pic shows the gap created because of the block stopping the nose closing completely.

Ba349 Natter - 0034 Nose Mouldings 5.jpg

Ba349 Natter - 0036 Nose Mouldings 7.jpg

Ba349 Natter - 0035 Nose Mouldings 6.jpg
 
Finally the two halves were glued together using the poly cement/glue and taped together. Not too tight on the tape and eyes open to make sure the two halves didnt 'jump' over the intereference block and close up.

Once taped and kept an eye on it was left for a fair few hours to set off fully.

Ba349 Natter - 0037 Nose Mouldings 8.jpg
 
Once fully dry the tape was removed and the nose cone given a sanding along the seams. The gap created by me opening the nose cone up a bit was filled in with squadron green putty and left to dry out.

Because the gap was quite deep it took a second application of putty. Although the fit was pretty good, being obsessive, I decided to run along the entire seam with the green putty as well.

Once dry the whole thing was sanded down.

I have to say the green putty stuff is awful to work with, on sanding it managed to dye everything green and clogs up snadpaper like nothing else. So buy lots of sandpaper if your doing this kit for sure :)

A plastic buckle was also added internally to the nose to run across the gap in the nose/body coupler flange. The reverse side of this was also filled with putty and sanded.

Pic 1 - First application of putty to the large gap created by the spacing of the nose cone.
Pic 2 - First dode of putty sanded and now a comnplete run around the seam with more putty.
Pic 3 - The 'buckle' applied to the gap in the nose flange.

Ba349 Natter - 0038 Nose Mouldings 9.jpg

Ba349 Natter - 0039 Nose Mouldings A.jpg

Ba349 Natter - 0040 Nose Mouldings B.jpg
 
And now its time, now that the body tube is dry and fully sorted out, two hits of aliphatic to close up any seams between the rings and the body from both the nose end and the tail end its time to put the rear end on the Natter.

As mentioned earlier everything was measured up to make sure that the motor tube was flush with the rear of the plastic tailcone at an earlier stage. Test fitting was done and all appeared well. The plastic tail cone did need a small amount (and I mean a tiny amount) of force to close it onto the motor tube fully.
With final test fitting done I applied some epoxy (Araldite Rapid) to the rear of the motor tube and the interior of the body tube and pushed the plastic rear end on.............only to notice a few seconds later that the bloody plastic rear end had been pushed inside the body tube past the flange. A few frantic moments :y: of trying to part the two for a second attempt proved pointless. The Araldite Rapid had done what it said on the tin and dried fast - like instantaneous in a way it has never done before. No idea also why the rear end fitted inside - it never had before on any test fittings :cry:

There you go - downed by the Noris Natter, best laid plans and all that :(

Now this had an upside and a downside (luckily) the down side was that as a result the motor tube protruded out from the back end of the plastic tail. The upside was that as the tail had now wedged itself tight there was less filling to do around the join.

Some patient greeny puttying plus some wood filler on the tube produced a fairly smooth join between the two (only primer will tell if this is so) and I used some green putty to fair in the protruding motor tube so it looks quite neat.

Scale fans should note that the real thing did not have a round back end anyway - it was oval with the motor recessed somewhat inside.:tongue:

Heres a pic of the rear end fitted to the body tube plus a close up showing the result of the cock up and the protruding motor tube.

Ba349 Natter - 0050 Body and Tail.jpg

Ba349 Natter - 0051 Body and Tail.jpg
 
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Heres the rear end with some Squadron green putty to mask the join. The up side to the error was this would have needed filling anyway. It just needs a bit less now and in many ways the filling is easier.

The motor tube area was also given some green putty to fair in the rather ugly looking protuberance of the motor tube.

Finally the body tube was given some filler to help with concealing the joins.

Ba349 Natter - 0052 Body and Tail A.jpg

Ba349 Natter - 0053 Body and Tail.jpg

Ba349 Natter - 0052 Body and Tail B.jpg
 
Finally the whole of the body can be put together for a viewing so I can get some idea of size and you dear reader can ohh and ahh :)

In fact putting it all together showed up another issue for the obsessive with time on their hands. The forward body tube had a tendency to want to go back to being round and spoiling all of the hard work in getting the nose the right size. We'll have none of that in the Reich thanks very much and cardboard tubing vill be mad to obey, Ja !

So to bend the cardboard to my will I decided to try something out.

A strip of card was measured up to be the right interior size and to fall short by the right amount for the nose cones coupler area. The card was coated with epoxy and had a nomex strip applied which, once the epoxy was dry was cut to the same size as the card. Test fitted to make sure all was well (it was) and then the card side of the nomex/card strip was given another whack of epoxy and the whole thing slid down into the nose end of the body tube making sure not to get any glue on the area where the nose cone would be. For safety a strip of weak masking tape was put over this area as well. The nose was put in and the whole thing gentlly pressed to form the body tube to the same shape as the nose cone.

It worked too - the nose end of the body tube now holds the shape well and the slight ridge of the nomex/card interior stops the nose cone having any tendency to push back into the body tube.

Once all was dry the Nomex was given a hit of aliphatic to help it resist heat from ejection.

Heres a pic of the internals with the nomex strip applied.

Ba349 Natter - 0056 Nomex Shaper.jpg
 
In the next thrilling update to the build thread find out how I take some papier mache mothballs and some cardboard tube and create perfect miniatures of Schmidding SG34 solid fuel rocket boosters :)
 
...

Once all was dry the Nomex was given a hit of aliphatic to help it resist heat from ejection.

Heres a pic of the internals with the nomex strip applied.


Try to keep it as light as possible. Furthermore it's not needed with Klima motors. Be patient.... :wink:
 
Try to keep it as light as possible. Furthermore it's not needed with Klima motors. Be patient.... :wink:

I did try to keep this one light - honest - but I am always torn between light and looking good. This kit needs a lot of filler to get stuff looking good. I havent come on to the boosters yet but they have needed two hits of filler just to get the noses of them looking right and truth to tell I am still not happy. On the upside theres not much more to fill after that. The fins/wings are quite light and apart from paint and nosewight the kit still feels very lightweight overall. Far less than my Fire Lily.

Ahh the Klima motors - no sign of them in the UK and I have a batch of D12-3s to use up.

As the Natter is known to be a bit weird in flight I will be filming its firts flight with a profusion of cameras - if it crashes I want some decent film. I dont mind a crash so long as I have footage :)
 
Over time I have learned to love the green putty. Yes I glop it on because I am too lazy for two or three light coats. Yes I use 60 grit sandpaper to hack it down. Nasty green dust everywhere, clogged up sand paper of all grits, green stained fingers where the thinner didn't quite get it all off from my squeeze out of the tube then finger down technique. But it does smell nice and sweet. . . oh so it is carcinogenic, you only live once and must sacrifice the body for model rocketry perfection.

D12 3 shotgun ejection charges beware! This little Natter is prepared.
 
Well tonite was a disaster. The rear stabiliser/rudder fin was added but thanks to me not being alert it ended up being glued down wrong so i have just spent an hour cutting it away and refinishing.

But heres a question.....as its paper card to plastic what glue did you use on yours ? I was going epoxy because I cant work with superglue for this kind of thing. The epoxy didnt do a great job and I am thinking of switching to a weird glue I have which glues anything but its very messy stuff to use. Its called Bostik Serious Glue, I have no idea what its made up from, its a single tube stuff but it goes stringy very easily, hence the mess but on the upside things stuck with it tend to stay stuck VERY hard. I have used it in the past to stick all manner of things together, metal to metal, wood to rubber, even stuck a rubber sole to canvas with it on some shoes and they are still stuck down firmly so its mighty powerful stuff but messy as I say.

Also, and I know the Noris measurements arent likely to be right, but while the fin was attached I was messing around and found that the elevators if set at the measurements Noris state in respect of the tail fin lead the elevators to be in a downward position. If set level the elevators are slightly too long for the tail fin. Now it may be Noris wanted the elevators set in a slightly down position for reasons of flight stability, I am not rocket scientist enough to know but I can see its possible.

I am minded to ignore the Noris dimensions and just set the elevators at a horizontal position with respect to the airframe. Can I ask what others may have done on this ?
 
Astro.....she is looking great! I like the fix o the nose cone and the tail....Squadron putty is great stuff. I am building a F-4e right now so I am immersed with Squadron putty...I am using the white putty. Not sure what the difference is between the white and the green, but the old guy at my local hobby shop says the white putty is finer grained.

this is a great thread! Fun to watch this one come together!
 
I used the dimensions in the directions and super glued the card stock to the plastic after a coarse sand and Xacto knife cross hatch scoring. You can get CA made for plastic bonding. It bonds fairly well even on the small surface edge of the card stock. The fins did not aline so I broke the tail off, scraped back down to plastic, hacked the horizontal stabilizer until the elevators were parallel to the wing by eye. Attaching the card stock only using its edge and running a fillet of thick CA and using accelerator will hold for awhile (may require repair after every flight), 5 min. epoxy maybe a bit better but messier and more difficult and time consuming on taping the fillets. Paper tabs over a larger roughed up area would be better yet with CA or epoxy but even more work. Welcome to the wonderful world of the Noris kit. The directions show the parts going together, it is up to you to figure out how to do it. Just wait until you get to the booster attachments on the R -7 kits. How does Skill Level 6 feel now? Never a curse word uttered, never a bottle of glue thrown across the room, never a fist pounded or adult beverage consumed.

You can tough up and smooth the card stock later with sanding sealer dope.
 
Astro.....she is looking great! I like the fix o the nose cone and the tail....Squadron putty is great stuff. I am building a F-4e right now so I am immersed with Squadron putty...I am using the white putty. Not sure what the difference is between the white and the green, but the old guy at my local hobby shop says the white putty is finer grained.

this is a great thread! Fun to watch this one come together!



I use the green stuff on white plastic and the off white stuff on colored plastic.
 
I'd be suspicious of any non parallel setting of the horizontal stab. By down, are you saying the leading edge or trailing edge is down? If it is the trailing edge being down, it might be to offset the offset drag of the vertical tail and horiz stab, but it would have to be pretty minor....

Anything with the front of the horiz stab lower than the rear would be up elevator and would make it worse....

Frank
 
I agree with what others have said. The upper fin with the tailplanes may cause a little more drag than the plain, smaller lower fin, which could in theory cause the rocket to pitch "up". Angling the tailplanes very slightly down could counteract that. I've built rockets with asymmetric tails like that before (my own crude attempt at a Natter and my early Feuerlilie F25 based on the Luft46 diagram), and they didn't pitch like that. The tailplane angle would need to be very slight and precisely matched to the drag (which will be different to what Noris planned because you're using a higher thrust motor), otherwise it will do more harm than good. Setting the tailplanes to be horizontal, i.e. parallel to the wings, is safer. To really be safe, when you launch the Natter (at least for the first time), be sure one wingtip is pointing towards you. That way if it does pitch, it won't loop over and hit you!

For gluing, I tend to use CA to tack down the fins, then epoxy to fillet them. That ought to stick pretty well anything to anything else. Scuff the plastic cone with sandpaper to roughen the surface, which will give the glue a better chance to grab than if the plastic is smooth.

Good work so far! I'm looking forward to the next report...
 
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