Brengun 1/72 BP-20 Natter “Mustermaschine M23”

The Brengun Natter M23 captures the look of this fatally flawed flying machine very well.

If the key to defence is a good offence, how are you supposed to defend yourself when you’re on the ropes, and the enemy has you outgunned, outnumbered and on the run? How do you protect what’s left when pretty much the whole world has you in their crosshairs and isn’t interested in pulling any punches? Is there a silver bullet that can even the odds?

If this sounds like narration from an action movie trailer, it isn’t. It’s a serious situation and they are the questions that faced the heads of the German Armed Forces in the second half of WWII. As the Allies gained strength and America’s manufacturing capacity was brought to bear against Germany from the west and south (and east, really, since so much equipment was “lent” to Russia under Lend-Lease agreements), things just spiraled downwards for the Germans. One of the key areas that demanded redress was the loss of air superiority that was allowing the USAAF by day, and the RAF by night, to bomb Germany, it’s industries and population, into a previous age.

Just making more planes wasn’t ever going to be the answer. Even making better planes wasn’t going to tip the scales on its own. Too late, the various figures in the High Command and in the ridiculously politicized Nazi Military/Industrial Complex realized that it would have to be some kind of leap of high technology that saved the German people and territory from utter destruction. And so, the world witnessed the deployment of the Me-163 rocket fighter, Me-262 and Ar-234 jets and even the first ballistic and cruise missiles in the V2 (A4) and V1 (Fi-103). Many of these, though, didn’t really tackle the problem at hand; the bombers. How can you stop a bomber stream of 1000 planes, when even 10+% PER DAY losses didn’t slow the USAAF down?

Against a similar juggernaut twenty-something years later, the North Vietnamese turned to SAMs to punish the bombers and try to roll them back. However, German SAM technology wasn’t well enough advanced, or even funded, until very, very late in the war. However, the answer was surprisingly similar to a SAM; it was the Bachem BP-20 Natter. This combined features of the Komet rocket interceptor and a modern SAM in a very unusual way. The Natter was designed as a highly transportable point-defence interceptor. It was to be vertically launched from stripped down trees or even special trailer/launchers and boost into the Allied bomber stream. Its high speed and tiny size would protect it from interception, and its armament of rockets would deal a devastating blow to anything they hit. Such was the plan.

However, like so many desperate ideas at the end of the War, the Natter was far from perfect. The main flaw was that it needed a human for a guidance computer during the attack run, but that the launch stresses could easily overcome the pilot’s ability to control the tiny rocket in its boost phase. A primitive autopilot was the answer, and many unmanned launches of Natter test vehicles proved that it could work. Not only that, but the plane itself was a semi-decent glider, as manned test gliders proved. With pressure and desperation mounting, not to mention political interference running amok, the push was on to get the Natter into service. Thus, the time came for a fully manned flight; the time to combine the manned glider flights and unmanned launches into a full flight cycle was nigh. The pilot for the mission was to be one Lothar Sieber, and his mount, the machine that would point the way to all future space flight, was the Mustermaschine numbered M23.

Despite being a tiny wooden tube with one of aviation history’s most dangerous engines stuck in the back of it, that the craft was semi-expendable and that none were used in anger, the Natter has always had quite a solid following in kit form. The almost futuristically post-apocalyptic appeal of the Natter, the fact that something so radical and crazy wasn’t just tested, but actually produced and deployed, has lent it an air of mystery and legitimacy that it probably doesn’t justify. If it helps, they were hoping to make them out of heavy cardboard if wood ran out. Yep… just like a giant version of those Estes model rockets we’ve all launched in our younger days.

One of the newer Natter kits is the Brengun 1/72 Mustermaschine M22/M23. This means “Trials Machine”, and the model represents the penultimate unmanned development unit (M22) and the first manned unit (M23). For more on the kit itself, check out the Out of Box review:

1/72 Natter M22/M23 (OOB)

Building the Natter:

Like almost all planes, the first thing on the Natter that gets done is the cockpit. The cockpit consists of a back wall, a floor board, some rudder pedals and a control stick. There’s also a separate headrest and a seat cushion, and there’s a front wall to the cockpit to which mounts the instrument panel. At first, this doesn’t sound like a big deal, but it actually is. The Natter’s instrument panel is a very distinctive shape and it’s nice to see a good replica of it.

This is the instrument panel and forward bulkhead. Not much there, but there isn’t in real life, either…

The cockpit fits together well, and looks good. I believe that Natter cockpits were likely unpainted wood, but since I wasn’t thinking and was in “Must paint interior… use interior green…”-mode, I did everything in said shade of grey-green. This was given a light wash of Citadel Nuln Oil to bring out the detail, but not so much to make it look used. After all, M23 was new when the first pilot, Herr Sieber, strapped into it. The instrument panel was painted black and the dial rings were highlighted with a silver Prismacolour pencil crayon. The exhaust nozzle was assembled and painted Model Master Acrylic (MMA) Steel, with a similar light Nuln Oil wash. I did the seatbelts in dark green and installed the two shoulder belts. One of the lap belts went spiraling into oblivion as I was cutting it off the fret, though. I chose to leave the lap belts off. To be honest, I don’t like the belts. They look far too small and thin, and nowhere near beefy enough for a rocket like the Natter.

Those shoulder straps look dinky, but the seat is nice. Wait, why is the opening a big square? Yeah… that’s a good question, with a bad answer, as you’ll see.

The cockpit and engine nozzle fit into the fuselage well, and there was no problem closing the halves together. The fit was excellent, and very little sanding was needed, which also means that there is only a little bit of re-etching that was required in order to get the detail that was sanded off back again. The wings fit nearly perfectly into “pits” in the body. As for the tailplane, it fits onto the stump at the rear of the plane using two locating nubs. Sadly, these are useless. They don’t fit the holes in the stump, and are far too large. Trimming them smaller, or removing them completely, is required. I decided to just cut my losses and chop them right off. Ironically, once they’re gone, the tailplane fits very well, as do the vertical fins/rudders. The bottom rudder is likewise afflicted with “nubitis”, and the locators on this piece should be removed for ease of installation.

The separate rocket nozzle is nice on this kit, and adds quite a bit to the finished product.

The nose piece does not fit perfectly, but with some sanding and reshaping, it can be made to look fine. It’s still not terrible, though. If you’re used to Matchboxes and older kits (like me), then this is minor cosmetic surgery at the most. The four Schmidding boosters that fit on the rear fuselage look nice, but are far and away too complicated. On the old Heller kit, the two boosters and their connector brackets were a single piece, and they looked good. The Brengun kit has each pair of boosters in halves, and the nozzles are separate, and also in halves.

Thus, the boosters are 12 pieces, instead of two! Why? I really don’t get it. This is unnecessary complication on the order of what I’ve seen in the Zvezda Mig-29SMT. It seems like this is a step backwards, to me, given the Heller’s superiorly simple parts. So much for the “KISS” (Keep It Simple, Stupid!) principle, I guess. This is a lot more sanding and finicky work than I was willing to put in, so I just left the boosters off. As a bonus, you almost always see Natters with the boosters, and never without, so the lack of boosters adds visual interest! Gotta love irony!

This shows the Brengun M23 with the old Heller “production-type” Natter. Note the boosters on the Heller; nice single pieces. Note the lack of boosters on M23; I’m not assembling 12 pieces to get what should have been done in two!

The cockpit canopy, though, is another matter altogether. I can’t really give it points for anything. Firstly, it is quite thick and surprisingly foggy. The line dividing the opening and fixed part is very fine, and needs to be rescribed. The lines for the window frames are even finer, so fine that it is almost impossible to mask them! I created a miniature light table using an LED trouble light that allowed enough backlighting through the canopy to allow me to see where the frames are supposed to be so I could cut the masking tape.

This shows the cockpit on the little LED “light table” I used. The “bars” on the canopy are so small, you can’t find them through the Tamiya tape otherwise!

Once this is done, the canopy can be fitted into the plane. Oddly, this must be done before painting, since the clear part also has part of the fuselage with it. This reminds me of something I’m used to seeing on airliner kits, or really old models. Why Brengun did this I’m not sure, but it means the canopy must be installed so that the seams on this part can be sanded and puttied smooth. This also means the separation line between the front windscreen and the fuselage has to be scribed in. Again, this is an odd bit of “WTF-ery” on what should be a pretty simple little model. Even worse, the canopy doesn’t fit worth beans! It is too long, too tall and too thick. It runs into the headrest as well as the square tabs on the headrest, which must be trimmed to fit. The canopy must then be sanded short, as well as a bit taken off the bottom rail, in order to make it fit.

Here you can see the putty that is required to fair the cockpit in successfully. Not sure why Brengun went this route, but it is not a wise choice.

See… this is why building things like Matchboxes and Farpros is important. Even on a nice, new kit, you’re going to run into things that make you go back to the basics. If you’re used to Tamigawa wunderkits, you won’t even know what to do. It all builds character, just like walking to school in the snow uphill both ways. Punks. Get off my lawn! Oh, sorry… I digress…


When it comes to painting, there’s a bit of debate about what colour the Natter M23 should be. This is because there is some thought that the undersides of at least M23, and maybe M22 as well, were not black, but red. The reason it’s impossible to conclusively determine this is because with the black and white film used, red appears dark grey or black. In the few photos of M23, such as that on the back of the box, it is clear that there is a dark colour on the underside. It’s also clear that the fuselage stripes are a dark colour, but a shade or two lighter. You can argue, since the stripes are given as red, that the fuselage has to be black on bottom.

However, you can also say it’s a slightly darker red. Given that it’s a test machine, having a red underside seems more logical to me. It would be easier to track with the naked eye or optical instruments, and locating the parts of the plane after it came down post-flight would be easier with a red underside. After all, red shows up in a field, black does not. Not only that, but why woudl the underside be black in any case? It’s not like the Natter is a night fighter or night bomber, and those are usually the only planes that traditionally have black undersides. It makes no sense to have the test unit painted black, to me, so I decided to go with the red because a.) it’s more striking and b.) it’s more logical. Also, the Classic book on the Natter has a full page CGI image of M23 on the launch rail, and it has a red underside.

If it’s good enough for the “Classic” book on the Natter, it’s good enough for me. Besides, the red looks cool!

I decided to use a red that was slightly darker than the stripes provided, to give the same slight contrast as in the photos of M23. The red was a Model Master Acrylic (MMA) Guards Red mixed with a bit of Poly Scale ATSF Red. I airbrushed this onto the underside of the wings and body, and then masked it off. I reprimered with Colorplace rattlecan primer (because painting anything over red is impossible) and then used MMA RLM 65 light blue for the rest of the plane. Over this I used MMA Dark Green squiggle, which was just randomly applied using my “handwriting” approach. Just write your name with the airbrush while moving the target; it’s amazing how well it works!

The “scribble” effect of the green over the light blue produces a very nice mottling effect.

Upon unmasking the underside, I found a few little runs under the tape. However, since the paint is Model Master Acrylic, touching it up posed no problem at all. To highlight the panel lines, I decided to rely on pastels alone, rather than first pencilling them in. However, I did use pencil to highlight the control surfaces, since there’d be actual ‘cuts’ in the plane there, and the lines would be darker.

I glossed the Natter using Future, and sanded everything smooth. I then applied the decals. I knew from other Brengun kits that letting the decals curl is a death sentence, and this time I was ready. The decals went on beautifully; kudos to Brengun for such flexible and conforming decals! Even the long stripes went well, and they settle down even without decal setting solution (which I don’t use). While the photo on the box shows a forward red stripe near the division of the canopy and windscreen, the colour paint plan makes no mention of it. This is a particular weakness of Brengun’s paint plans. They very often don’t match any photos Brengun includes, and they don’t even agree with the box art sometimes! One other major issue is the placement of the T- and C-Stoff decals. The “T” is correct on the forwardmost spine door. However, the paint plan shows the “C” on what are actually inspection doors for the Walter rocket motor. The real filler caps for the C-Stoff tanks are down low on the sides, near the division line of the paint.

With the decals on and Futured down, one more light sanding got everything evened up. To flat coat the Natter before applying the pastels (since they work better on flat paint), I used Delta Ceramcoat Matte Indoor/Outdoor Urethane Varnish thinned with water and alcohol to get a “dead nuts” flat finish. To bring out the panel lines, I ground up custom red, light blue and dark green pastels; each was a shade or two darker than the paint over which they were to be applied. First, I applied a thin layer of each colour over the appropriate paint, and used Varsol to thin it down and wash it over and into the matte surface. This effectively is a filter wash, but at a cut-rate price! With excess pastel gently removed with a Q-tip, I re-flatted the Natter, locking in the filter. I then applied heavier pastelling over the panel lines and used Varsol to dissolve the dust and move it into the lines. This also gives a post-shading appearance, and I was amazed at how well it filled in the lines.

This view shows the proper placement of the “T” and “C” decals, as well as some of the aging on the “wooden” pallet used to support the Natter during transport.

I used the same approach for aging the shipping pallet/cradle for the Natter. After gluing the styrene “beams” to the resin ends of the cradle, I painted the whole thing MMA Dark Tan. I then used greyish-purple and light grey pastel/Varsol washes to give the wood that “greyed out” look one would expect from worn timber. I figured they likely wouldn’t bother cutting new timbers for something as impermanent as the cradle; they’d need all they could get for the Natter!

The last bit of paint was some semigloss varnish over the whole surface. This is just my Matte Varnish with some Future added for gloss. A tense moment is always to be had, I find, when unmasking the canopy on a model. I was quite pleased to see that the Natter’s glass survived quite well. Despite all the near-proximity wet sanding, the Tamiya tape I used stayed down and didn’t let any paint through. I applied a layer of Future over the now exposed “glass” bits, and put the Natter in my dehydrator to dry thoroughly for a few hours.


The Natter, as a weapon, was a failure. Despite a few airframes being deployed as part of Operation Krokus, it never saw combat. Like other Nazi rocket fighters, it was temperamental and more of a danger to its pilot and ground crew than any enemy it would face. However, as a piece of engineering it is a very interesting case study. It is the centre of the Venn diagram wherein desperation, ingenuity and overzealousness overlap.  It’s no wonder that it has captured the imagination of modellers since the end of WWII.

Brengun’s little Natter kit is a very respectable kit, even in this small scale. The detail is excellent and the fit of all parts, save the canopy, is good, especially when you take the posts off some of them! There’s even an aftermarket set of PE for the exhaust nozzle control vanes, if you want to get seriously hardcore! Brengun has paid a lot of attention to the aircraft and made available an interesting range of kits for everyone from rocketry historians to rabid What-Iffers.

This kit is not complicated, but it is also a bit of a challenge. It’s not one I’d recommend to a child or a novice builder, but someone with some modelling experience will be able to do well with it. While a couple of the details aren’t quite right for this kit to be M23 (no wing mounted Pitot tube or loop antenna on the rear fuselage), it does a darn good job to the casual eye. With some careful paint work and shading, it can be made into a most convincing replica.

I’d recommend this kit to anyone interested in the subject matter as well as anyone who has a penchant for the bizarre. If you don’t expect a “shake ‘n’ bake” model and are willing to put a bit of work into it, I think you’ll be pleased with the result.

Herr Lothar Sieber was the first man to strap into a vertically launched rocket. He was a pioneer of a new kind of flight, a mode that we still use today to leave our planet and send ourselves, and our robot servants, into space. That such a lashed-up machine failed at the worst time and killed him is no surprise, but it doesn’t take away from his bravery in being willing to make the attempt. I am glad to have this model finished as M23 as my own little way of paying tribute to the mix of genius and insanity, and the combination of bravery and outright negligence, that produced this first faltering step towards manned rocket and space flight.

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