Douglas B-26 Invader (oz4725)
About this Plan
Douglas B-26 Invader. Control line scale twin. K&B 29 engines shown.
Quote: "Douglas B-26 Invader, by Lt ER Dick Atkins Jr, USAF.
Have you ever considered building a multi-engine scale model but for some reason the project seemed too complicated or not worth the trouble required? Well, sweep off the old workbench and dig out the glue pot, because it's as simple as any single-engine job you ever made.
This was my first multi-engine and was so successful (in the money three times in three contests) and handled so beautifully that I plan to build multi-engine scales from now on. There are a few tips you should have to make your ship a success.
First and most important is the choice of two good dependable engines. Without these you'd better not even start on this ship. I chose K&B .29 Glo-Torps for the B-26, but if you have two pet 29's of the same power they will do the job. However, you must have engines that will start on a couple of flips and will run steadily at all times.
Secondly: Some type of cut-off device similar to the type used on team racers is very desirable. If cut-offs are not used the outboard fuel tank must be smaller so it will cut first. Then the inboard engine will tend to turn the ship out of the circle and keep the lines tight until it quits running. Incidentally, this model performs safely on either engine. For safety's sake, however, the ship is trimmed with ailerons and rudder to turn ship outwards on circle.
Third: Don't wait until the day of the contest to fly your ship for the first time (this goes for any model). As soon as you have the ship assembled throw on a couple of coats of fuel-proof dope, dash out to the field and find out how she handles and make the necessary adjustments then for a perfect night at the contest later. I've seen many potential prize-winning models smashed to small piles of wrap because the builders didn't have the heart to test fly them before the contest, and as a result didn't have the slightest idea how they handled or whether they were properly balanced or adjusted.
Now a little about the ship. The Douglas B-26 (designation prior to 1949 was A-28; the Martin wartime B-26 Mraurader was dropped from service in 1945) is an all-metal two-engine mid-wing fighter-bomber and ground support airplane carrying a crew of three or four depending orn its mission. With a bomber nose it is used for low and medium altitude bombing. This version mounts two .50 caliber mg's in the nose and four 50 caliber mg's in two remote-controlled turrets in the rear of the ship. It flies at speeds in excess of 350 mph.
The fighter version mounts 50 caliber mg's in the R/C turrets and three in each wing and eight in the nose, in addition to bombs and numerous rockets. This is the version on which this model was based.
Let's build the model! Choose two pieces of 3 x 36 in medium soft sheet balsa of the same grain and quality. This is very important - so the sides will bend equally. The balsa may be tested by placing it on the edge of a table and weighting one end with a heavy object and placing two equal weights on the other end of each sheet of balsa to see that each piece bends the same distance.
Cut the sides to shape and join them at the tail end, placing a V shaped gusset in the slot and using glue freely. Secure the sides with a C clamp and allow to dry. Install former F-7 and cement. When these are dry cement F-1 in place. Mount landing gear formed from W9 wire to former F-2 and cement in place. The balance of the fuselage formers and the cockpit floor may then be installed.
Cut the bellcrank mount from 1/4 in plywood and mount in proper position and reinforce with 1/4 sq hard balsa. Glue all top and bottom and nose blocks lightly to fuselage sides and carve to proper shape. Sand fuselage until it is smooth..."
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Update 21/03/2015: Replaced this plan with a clearer copy, thanks to bernd_57.
Update 09/10/2018: Added 'Additional Notes' file, thanks to dfritzke. This contains the further notes printed on the full size plan, as referenced at the end of the article ("Additional construction details are on full-size plan available from Air Trails").
Supplementary file notes
Additional notes file.
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