Unicraft 1/72 KhAI-3

UNICRAFT 1:72 KHAI-3

Reviewer: Johan DeWolf (rec.models.scale)
Kit Review submitted: 15 May 2006

Kit Details

Aircraft: KhAI-3
Scale: 1/72
Kit: Unicraft
Parts: 26 in cream-colored resin + 4 clear vacuformed.
Surface detail: engraved
Decals: none
Accuracy: needs work.
Price: bought for about $10, - on eBay as part of a lot.

History

In the 20’s and early 30’s aircraft designers looked into many new ways to build aircraft. A particular popular new concept was the flying wing. A flying wing is lighter because there is no need for a fuselage, and as there are no tail surfaces there is less drag too. Especially in Eastern Europe and Germany many flying wing gliders were tested. In 1936 A.A. Lazarev of the Charkov aviation institute (Aviavnito) designed and built a large powered flying wing intended for commercial use. The straight center section was built of steel tube covered with wood. An Mikulin M-11 radial engine (same engine as on the much smaller Po-2 and UT-1/2) was attached to the front of this section, and a vertical tailfin to the rear. This center section was flanked on either side by a 5 seat cabin built of wood. Outboard of the cabins triangular wooden wings were fitted. The aircraft had a fixed landing gear with a steer able tail wheel. The wings were fitted with large flaps and ailerons, and at the tip spoilers were added. It weighed about 2200Kg. The design was first flown by V.A. Borotin in 1936. He reported pleasant flying characteristics and good stability. Maximum speed was 135 km/h and landing speed a mere 60 km/h. It would take off after a run of under 250m. However the ailerons and rudder proved rather ineffective on their own, making it difficult to turn. The spoilers at the wing tips rectified this problem. Using them together with the ailerons provided excellent controllability. State acceptance trials proved satisfactory too. The Khai-3 was successfully used as a passenger and cargo plane in the Moscow region in the late 30’s. The Khai-3 was the first and, as far as I know, the only flying wing airliner ever used commercially.

Picture 7
© Johan De Wolf 2006

The kit

The small box this kit comes in is packed full, as this is a fairly large model. The parts are well cast with fine engraved panel lines. There are no bubbles in the major parts but some of the seats did have a few. The smaller parts need some clean up but nothing out of the ordinary. The landing gear has been cast around a metal pin to provide enough strength to carry this heavy model. The larger parts have rather heavy poring blocks on them and, as the resin is very hard, it is quite a chore to remove them. The vacuform canopies are thin and very clear. The frame lines are a very faint though. Molds for the canopies are provided in case you might prefer or need to make new transparencies. There is a leaflet with a short history and technical data, and an A4-size scale drawing. There is no actual construction diagram but since there are only some 30 parts it’s easy enough to figure out what goes where. There are no decals with this kit as the KhAI-3 apparently had no markings.

Accuracy

With esoteric subjects like this, the reference material is very limited. In fact there is only one photograph known of this machine. There is also an artists drawing of the aircraft in flight, on which the box art is based, which is reportedly pretty accurate. The scale drawing that came with the kit shows a machine with short passenger gondolas (original design?). The photograph and artists drawing show the long gondolas. The text with the scale drawing says it is only a rough sketch and that the kit is based on the photo and artists drawing. As such it compares very well with both in shape and configuration. Only the wing tips don’t look quite right, but that’s easy enough to correct. When looking at details I found that both the flaps and ailerons are too far outboard on the kit. Also the size and position of the wingtip spoilers are wrong. A few panel lines on the model didn’t make sense to me, so I decided to fill and rescribe them in more logical places. Now for dimensions: the length is spot on, but span is 1cm under the quoted figure. I decided to ignore this as with such an obscure aircraft the data may well be wrong. The last thing I noted was that the prop in the kit was rather small. This should have set off alarm bells but it didn’t, more on that later.

Picture 6
© Johan De Wolf 2006

Construction

I am not particularly interested in civil aviation. But when the package, containing a batch of kits I purchased on eBay, arrived on my doorstep, I couldn’t resist starting on this one right away. It is just such an odd machine, and to think it was flying commercial flights even before the Second World War makes it even more amazing.

Anyway… I started with removing the poring blocks. After breaking off two razor saw blades on it I finished the job with a steel saw from the toolbox. I cleaned up all the parts and filled the bubbles in the seats. I had to reshape the seats too, as none was equal to another. The first things to be glued together were the passenger gondolas. These were then glued to the wing mid section. Next the outer wing panels had their tips reshaped and thinned and were glued on to the gondolas. I noticed too late that the left gondola was slightly canted outward. Because the resin is so hard I decided not to try and break off the gondola to correct it. While filling the seams the kit slipped from my hands and made a nosedive too the floor…. Sigh. The nose of the left gondola nose was smashed into five pieces. I could find four, but the carpet devil must have made of with the fifth. After gluing everything together and filling the hole left by the missing 5^th piece it was back to regular construction.

The representation of the M-11 engine was a bit too simple to my liking so I had a look at my stock. I could chose from a resin replacement (including prop) from a Czech company (not much better than the kit part), the Neomega M-11 (which is a kit in its own right) and the Engines & Things rendering. I opted for the last. The Czech part set me thinking though. I looked up some aircraft that were also powered by an M-11 like the Po-2, Yak-6, UT-1/2, Sh-2 etc. They all used the same wooden prop, and it looked nothing like the thing in the kit. I discarded the kit part and decided to use the Czech prop. Dry fitting the engine and prop showed that the new prop could never turn in between the two gondolas… argh!!! In fact it needed about 1cm more space to be able to turn freely. Now where did I see that 1cm figure before…. Ohhh sh#*@#$@%^^. That will teach me to not dive headlong into model construction!

The model sat on my desk for a few weeks while I pondered what to do… bin it?, go with that silly kit prop? Or major surgery? I’ve only given up on a kit once (the highly inaccurate Revell Tsukuda Su-27) and I wasn’t willing to accept defeat again. I looked around on the web and found some pictures of a build KhAI-3. It was built out of the box and it just looked plain wrong. So major surgery it was! Out came the steel saw again and I cut through the model on its centerline.

As I had to rescribe the aileron and flap lines anyway I cut them out all together as well. I added 1cm between the two halves and glued the whole together again. Cutting the kit in half had destroyed the engine fairing so I made a new one from a Heller Mirage F.1 fuel tank. Several filling and sanding sessions later I was back at the point where the engine could be glued on. However I left it of, and put on the fin first. I also re-attached the flaps and ailerons at a slight angle to liven up the model a bit. Although the resin gear struts are useable I though it better to scratch built a new gear from plastic. I also replaced the wheels with items from the spares box. The kit is almost completely solid resin and rather heavy, so I thought it better to have a stronger gear.

In picture 1 you can see the model after surgery. It also shows the kit parts and the replacement parts side by side.

Picture 1
© Johan De Wolf 2006

Still skipping the engine, I turned my attention to the interior. To hide the mold line I first put in a new plasticard floor. Then I scratch built wing spar carry through boxes. The kits history reports that each gondola had six seats; the kit only has 10 seats though. I tried to fit 6 seats into a gondola but found that it would leave no place for the passengers’ legs. Luckily another source mentions 10 seats so that is what I went with.

The right gondola was detailed a bit further with an instrument panel, rudder pedals, some cabling, a flap control wheel and a stick. The vacu canopies fit very well. Picture 2 shows the left canopy fitted and the right gondola ready to be closed up. With the canopies in place, I finally glued the engine on. The last part I scrounged from the spares box was a venturi tube, and it was fitted to the right side of the nose of the right gondola.

Picture 2
© Johan De Wolf 2006

Painting and Decals

The only colour indication given with the scale drawing is that the aircraft was probably light grey all over. I find this a bit suspect. A lot of civil airliners from the 20’s and 30’s were either left natural metal, or were all over white or cream. I’m not particularly fond of white so I painted my model cream. The interior got a coat of grey green, while the seats were painted light brown with dark green upholstery. The gear struts were painted black. The engine was painted with various shades of Humbrol metal cote.

As mentioned before, there are no decals with this kit. The photo and artists drawing show no markings at all. However as the machine was used on regular flights it must have had a registration. Looking at photos from other soviet civil aircraft from the 30’s it seems that the registration was usually carried on the fuselage and underside of the wing. Some aircraft also carried the registration on the upper surface of the wing. As the Khai-3 has no fuselage and only a small fin I concluded that this aircraft probably had its registration only under the wing. I pinched the decals from a Yumkt A-7-3A altered them slightly and placed a registration under the right wing only.

As the colour scheme is rather bland I decided to weather the aircraft, and make it look like it might have looked towards the end of its career. I gave the model a wash with thinned aquarelle paint to bring out the panel lines, and make the paint job look worn and faded. I reproduced exhaust streaks with pastel chalk. The “walk ways” on the wings mid section were also dirtied up. The underside also got a few streaks were mud and debris thrown up by the wheels would have hit the wing.

Conclusion

I can recommend Unicraft kits only to the more advanced modeler as they are by no means easy. However Unicraft seems to be the only company producing kits of these very esoteric but highly interesting machines. I now have a very different shape sitting on my display shelves with a high “what’s that??” factor. And if anything, this kit has wet my appetite for more oddities.

References

History of aircraft construction in the USSR part I (up to 1938) by V. B. Shavrov.

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