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Old Mar 06, 2013, 10:42 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,532 Posts
Build Log
60" span Avro Lincoln in depron

This is all the fault of Steve85 and his Lancaster X thread. When he started it, I was just finishing my 60” depron Short Empire boat (a complete failure as a flying model, due mainly to lack of power but also to a rearward CG. It survived but is no longer in flying condition). I had a very successful series of 48” span depron twins but still wanted 4 motors and a bigger model. Steve’s 1/24th scale Lancaster is 51” span and a Lincoln at the same scale is exactly 60” span. Four 20g Blue Wonder motors would give masses of power. It was just a matter of finding a decent 3-view and doing some drawing.

The “Aeroplane” magazine for November 2008 has a whole section on the Lincoln and I used the 3-view from the article. A simple black and white ”Tiger Force” scheme would be easy to paint and might hide any small imperfections in my depron technique.

I should like to make it quite clear that this is not going to be a build of the quality and detail that Steve has undertaken. He is building a model that will stand close examination: My aim, as always, is to build a recognisable model that will fly well and land and take off from my grass patch. Retracts are essential, but all other detail is an option to save weight!

The Lincoln was designed by Roy Chadwick to meet an Air Ministry requirement for a long range heavy bomber to operate in the Pacific region against Japan. It was really a Lancaster with 18’ more wingspan and 7’ more fuselage, powered by RR Griffon engines with annular radiators. Although WWII ended before it could be used in its bomber role, the Lincoln served with the RAF from 1945 to 1963 (to 1967 as a test-bed) and with the Australian and Argentinean Air Forces. As any fule know, it was the basis of the Avro Shackleton which flew on into the ‘80s, maybe the ‘90s – I’ll have to check.
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Old Mar 06, 2013, 10:58 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,532 Posts
The tail surfaces are two thicknesses of depron (6mm for the tailplane and 3mm for the fin and rudder) bonded together with titebond, edged with balsa strip and then sanded to section. This method is so simple, very strong and and when finished, can be as exactly to scale as you are prepared to go. The glue takes a day to dry out - speedy builders might like to try gorilla glue instead.

In the past I have tried to keep the surface of the depron untouched, because it takes paint so well, but this does make it very vulnerable to damage. So once the sanding is complete the acrylic poly varnish comes out (commonly called WPBU) and a couple of coats with a sanding in between makes for a smooth surface. Old fashioned tissue paper is then applied with more WPBU in this now very well-known technique
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Old Mar 06, 2013, 11:07 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,532 Posts
The fuselage is a simple ladder frame from 6mm sheet with 3mm sides and some reinforcement at wing and tail saddles.

This basic section will be bulked out by HWC foam top and bottom, hollowed internally to take control pushrods and and wiring.

I did warn you that it was not going to be a detailed model!
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Old Mar 06, 2013, 01:40 PM
Oh no, not again!
jhspring's Avatar
United States, LA, Carencro
Joined Dec 2005
5,245 Posts
Quite slick, Mike. Glad you are doing a thread. I reckon a decent flying model is worth all the lovely, over-detailed, half-built models I have lying around my shop.

Regards,
Jeff
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Old Mar 06, 2013, 03:20 PM
The "pro" in procrastination
Steve85's Avatar
Canada, ON, Kingston
Joined Mar 2004
2,655 Posts
Mike,

Now we're talking! I can stand down the extra guards I've had in my workshop since you threatened to sneak off with my Lanc and turn it into a Lincoln. Since we're laying blame, it was your Empire boat that convinced me to experiment with Depron in the first place, so it's now come full circle! And as far as detail goes, I consider myself an "impressionist scale" modeller. It looks good until someone takes out a reference book and starts comparing it to the real thing.

Y'know, at the rate yours is coming together, you'll be finished before me!

Steve
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Old Mar 06, 2013, 05:02 PM
The Hun in the Sun
vonJaerschky's Avatar
Canada, BC, Comox
Joined Nov 2003
7,242 Posts
Great project, Mike! What are you going to do to people who come up and call it a Lancaster, though?
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Old Mar 07, 2013, 02:08 AM
Registered User
Spitfire1954's Avatar
United Kingdom, England, East Riding of Yorkshire
Joined Jan 2011
607 Posts
Great progress – Steve's Lancaster build has been great to follow on these pages – will be following this build with great interest.

Charles
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Old Mar 07, 2013, 02:09 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
12,891 Posts
Just had a quick read on the Lincoln to refresh my memory.

There was some interesting engine variations when they used some as test beds for jet engines.

From Wiki -
Lincolns were frequently employed as testbeds in new jet engine development. RF403, RE339/G and SX972 flew with a pair of Armstrong Siddeley Python turboprops outboard in place of the Merlins, and was used for the ballistic casing drop-test programme for the Blue Danube atomic weapon.[16] SX972 was further modified to fly with a pair of Bristol Proteus turboprops. RA716/G had a similarly placed pair of Bristol Theseus turboprops and later also flew with Rolls-Royce Avon turbojets replacing the pair of turboprops. Lincoln Test Bed RF533 kept its Merlins but had a Napier Naiad turboprop in the nose. It later flew, bearing the civilian "Class B" test registration G-37-1, with a similarly placed Rolls-Royce Tyne which it displayed at the 1956 Society of British Aircraft Constructors (SBAC) show, making a low level flypast on just the nose Tyne, the four Merlins being shut down and propellers feathered.[17]SX973 had a Napier Nomad diesel turbo-compound installed in a similar nose-mounted installation.[18] RA643 flew with a Bristol Phoebus turbojet in the bomb bay, and SX971 had an afterburning Rolls-Royce Derwent mounted ventrally.[

No mention of brushless electric power though

Good luck with the build Mike.
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Old Mar 07, 2013, 02:33 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
12,891 Posts
Oh boy!, now this is one possibility for the Lincoln -

Avro Lincoln Miles M.52 combination

Sorry, getting a bit carried away
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Old Mar 07, 2013, 02:54 PM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,532 Posts
I think the Lincoln wing also served as the basis for the Avro Tudor (not a happy marriage though!). I've had a day off today what with one thing and another, but will be back on the horse very soon. I think I'll leave the fuz as it is for the time being and build the wing CS, so as to the get the wing seat properly defined before making irreversible mistakes in the fuselage.

For the tail end, the plan is to have a servo embedded in the tailplane driving the two rudders on a very similar system to Steve's and the elevator servo in a more usual position just behing the wing cut-out. All the wires and linkages can be carried in the pink foam trough, out of sight and etc.

I can't decide whether to make the wing in three pieces, or just have it all in one big shed-filling mass. Porbably the latter, since it does not have to travel to Chilliwack in a box!
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Old Mar 07, 2013, 03:24 PM
The Hun in the Sun
vonJaerschky's Avatar
Canada, BC, Comox
Joined Nov 2003
7,242 Posts
Quote:
Originally Posted by Sopwith Mike View Post
Porbably the latter, since it does not have to travel to Chilliwack in a box!
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Old Mar 11, 2013, 12:55 PM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,532 Posts
Not much progress to report. The tail assembly is epoxied together and the moving surfaces temporarily hinged. The rudder system works "in hand" and just needs a servo and a couple of wires to complete.

The covering for these parts is Esaki tissue (from Mike Woodhouse Free Flight Supplies) and WBPU. However, the tissue is not very absorbent, so is slightly tricky to adhere to the depron. I bought a huge sheet of slightly heavier tissue from Channel 4 the other day, which is more open weave and might be easier to apply to the wings and fuselage.

I'm planning that the tailwheel will castor (like the real thing) partly to save weight at the back and partly because the simpler this model is, the more chance it has of flying. I'll put a rubber band in the system to keep it facing the right way when not under load.
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Old Mar 11, 2013, 02:41 PM
The "pro" in procrastination
Steve85's Avatar
Canada, ON, Kingston
Joined Mar 2004
2,655 Posts
Mike,

Now that looks familiar!

Steve
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Old Mar 11, 2013, 03:59 PM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,532 Posts
Hi Steve,

Apart from that big trim tab on the back of the rudder, it's all yours!

I spent an hour or so working out the details and drawing up the spars. I've gone for 1/16th with 3x3 hardwood top and bottom and a 6mm depron doubler (just to provide some glue area for the skinning). There will be a balsa/depron front spar out to the outer nacelles and a depron rear spar for the ailerons. Shopping tomorrow provided that the ice is not too bad!
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Old Mar 12, 2013, 10:56 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,532 Posts
I got quite a lot done over the past couple of days and the fuselage is starting to get that bulky look that is so surprising after being used to the skinny frame for so long.

The foam was cut in 4" sections, as that is the pitch of my little HWC gizmo I got from a craft store locally. I made the external cut first and had to discard a couple due to the usual mess-ups, then I did the internal cut, squared off the ends and glued all the top deck in place using a thin spread of aliphatic resin with a couple of foam-safe cyano drops on each glue face to mail it into place while the glue dries. If you keep the glue away from the very edge of the foam this makes an easily sandable joint - using other glues for this job, particularly UHU Por, makes sanding a neat edge almost impossible.

The hollowing on the undersurface sections will carry the extension from the rudder servo and the pushrod for the elevator, as well as hiding the servos and RX in the "bomb bay". More of that later.

Steve has promised me a cockpit when he gets round to moulding one in his vacformer: this will make my task much easier! I've looked for the 1/24th Airfix Mssie crew he mentioned but can't find them on the Airfix site.

Steve - do you have a link I could follow please?
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