BA Swallow (oz9360)


BA Swallow (oz9360) by John Coasby 1954 - plan thumbnail

About this Plan

BA Swallow. Free flight scale power model, for .5cc motor.

Quote: "THE ancestry of the Swallow II can be traced back to the German Klemm L.25, several of which were imported into this country during 1930-31. In 1933 the type was manufactured over here by the British Klemm Aeroplane Co Ltd of Feltham, the forerunners of the British Aircraft Manufacturing Co Ltd.

The final version produced in 1935 proved extremely popular in civil aviation and by September 1939 over 150 machines had been registered in this country alone. A number were privately owned, but the majority belonged to various schools and clubs.

Building Instructions: Lay plan side view over 1/32 in sheet and trace through the complete flat side view including slots for C/S, LE and spars. Repeat for other side of the fuselage. Cut out F12 and glue into position on side sheets then install all uprights

Prop up sides over plan view and install cross pieces, remove from plan, cut out and cement all formers with the exception of F1. Cut to length, drill for engine bolts and install engine bearers..."

Published in Aeromodeller Annual 1954.

Supplementary file notes

Article pages, thanks to Mary at


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BA Swallow (oz9360) by John Coasby 1954 - model pic


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BA Swallow (oz9360) by John Coasby 1954 - pic 003.jpg
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User comments

To whom ever responds, I'm sure i'm asking you to do my homework for me, but I've never scratch built anything before and this model seemed like a not half bad starting place, it even includes a materials list. However i'm not fully sure about all the things on the list, for example it says 'Strip 3 feet long' and 'Sheet 3 wide'. It also includes plywood of various lengths on the list but looking at the plan i'm not sure where id use it. It also says for the cowling '1/4" x 5/16" hardwood bearers' which i have little idea what it means and the list doesn't seem to have those dimension materials on it. In short, if possible, I'd be very grateful for an updated (and clearer) list so i can have all the materials and just try get started.
Teddy - 30/06/2024
"Strip 3 feet long" = balsa strip in the required sizes as noted in the materials list.
"Sheet 3" wide" = balsa sheet 3 inches wide in the thicknesses noted in the materials list.
The plywood is used for the former F2 and the undercarriage bearers.
pmw - 30/06/2024
Strip 36" length by whatever cross section called for, sheet 3 inches wide by thickness called for and most likely 36" length. the hardwood engine bearers can be maple, bass, oak if you need weight. The plywood is either 1/8" or 1/32" thick by the dimension called for but buy what is available to cover that and your good, usually 12-inch square or whatever they carry at the shop, I buy the commonly used thickness' in a 2'X4' sheet, so I have plenty on hand. this model looks like a good candidate for electric conversion which would mean no hardwood bearers.
Douglas Babb - 30/06/2024
Thanks to the both of you, always nice to have a bit of clarity. As for the electric conversion, it's certainly something to consider, if I stick with combustion would the hardwood bearers be required or just advised? The idea of a little engine running is always a fun one, at least more so than an electric motor.
Teddy - 30/06/2024
Looks like a nice model, simple and a convenient size. Electric is certainly the way to go, ask someone who is into electric what equipment to use. Another problem I see, no ailerons. Without a whole lot of dihedral, a low wing model won't turn well without ailerons. Not that it won't turn at all, but once it's started in a turn, it won't turn back. Ask me how I know. It's easy to add them, just build the wing as shown and then cut them out from the last few tapered ribs, then add mini servos for each aileron.
doug smith - 01/07/2024
Teddy, in regard to the bearers, if you built the plane real light and used a Cox .049 with tank mount, you would not use the bearers. If your motor of choice is beam mounted, then the bearers or a motor mount that bolted to the firewall and provided short bearers would be required.
Douglas Babb - 01/07/2024
Thank you both (again). I think, although somewhat regrettably, that electric power would be best. Ill have to find out what parts i need later once i get to that stage. As for the ailerons, would you agree that they should probably run from the tip (the height of the horizontal cut at about the top of the T.E closest to the tip) to W.6.? Just an estimate, but looking at pictures of 1:1 it seems pretty close. Thanks for all your help.
Teddy - 02/07/2024
Hi Teddy, this is a free flight design it will require extensive modification to fly as RC and is a job for an experienced builder/designer. It has many features unsuitable for RC, knock off wings, exaggerated right and down thrust and an inverted engine which will be difficult if you have no engine experience, as the question about bearer material indicates.
Can I suggest you choose something easier for a first build, something designed for RC, high wing and upright engine. There are lots of suitable designs on OZ.
Come back to the Swallow when you have more experience as it will just be heartache now.
Warren Brown - 02/07/2024
The rule of thumb for ailerons is 12% of the wing area. That means 6% for each aileron. Not carved in stone, anything close will be OK. Yes, more modifications for electric power and radio installation will need to be made. May I interest you in another option? My Guppy, designed from the ground up for electric power, no mods of any kind needed. Exceedingly easy to build and equally easy to fly, lots of them built and all still flying. Includes extensive construction notes and photos during build, you can't go wrong. No ailerons and no landing gear. I can't keep count, at least 14 built in our club. I still have mine, since 2014. See Guppy (oz13331). Any questions,
Doug Smith - 02/07/2024
The Swallow is very similar to the Klem KL 25. I built a couple of the Krick kits. One with an OS .40 four cycle and the second with electric power. I believe the Swallow is a license built derivative of the Klem, but might be off target. Anyway, it’s a high aspect ratio, short coupled aircraft. Both of mine have a lot of averse yaw from the ailerons and I have to run a lot of differential (more up than down) one the ailerons. Being short coupled it isn’t really stable in pitch. I really love the design for some reason, but I don’t find it fun to fly. If you decide to pursue the Swallow, take a look at the plans for the Klem. They are well drawn out and it is a fun build, see Klemm L25d (oz3159) Good luck!
Dave B - 03/07/2024
Dave B, the BA started as BK for British Klemm. Built under license from Klemm for the L25b, it was modified to meet British airworthiness standards and later the company name changed to British Aircraft, mods were angular tail shape instead of smooth and rounded plus different fuselage turtleback shape.
Douglas Babb - 03/07/2024
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