Robin Fowler 1:10 scale Short Stirling - RC Groups
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Feb 16, 2016, 10:09 AM
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Robin Fowler 1:10 scale Short Stirling


With the imminent publication of this model in Radio Control Model World (RCMW) in the March and April issues it is time to lay the groundwork for what should be called an AFTER-build thread - since the model has been flying for well over a year now.

The confines of a publication article (even when done in two parts) are far too resticted to allow publication of all the pictures taken during the building of the prototpye so this will be the plac to find - in due course - all those photos that didn't get into the magazines as well as a forum for asking for details.

My purpose in building a Stirling was primarily to prove that what at first may seem a very difficult model to build at a scale at which retracts and working flaps are essential is indeed possible - and acheivable with limited metaworking skills and tooling.
The supporting reasons consist of the place the Stirling has in history.

The Short Stirling was the first modern four-engined monoplane heavy bomber to enter service with the RAF and the only one designed as such from the outset. Both Halifax and Lancaster grew out of failed twin engined designs and entered service in their four engined forms some time after the Stirling had entered service.
From the outsetthe design suffered from the Air ministry's insistence that its span should be under 100 feet so that it could fit into any RAF hangar (despite the availability of some hangars of 124 feet width). This was to have serious implications as the short wings limited the service ceiling to about 18,000 feet so that the Stirling squadrons often took the brunt of the anti-aircraft fire. Crews of the later Lancaster and Halifax squadrons were therefore somewhat relieved when they learned that Stirlings were to be on the same raids. Stirling losses were therefore the highest of the three.
Despite this, if not restricted in maneouvring, it has been claimed that a Stirling could out-turn an attacking Bf110 night fighter.

The other limitation as the war progressed and ever larger bombs were introduced to the arsenal was the fact that the compartmentalised bomb bays (some being incorporated into the wings) were not able to carry bombs larger than the 4,000 pound 'cookie'. When the numbers of Lancasters and Halifaxes allowed it the Stirling squadrons were therefore relegated to second line duties such as glider towing and the dropping of supplies. Up until this point the Mk.III had been the most numerous type, but the Mk.IV was then introduced, having the nose and dorsal turrets deleted, with the final type (Mk.V) designated for transport and seeing the Stirling into the post war civilian market.

Many of the photos referred to in the design process were obtained from (and used here by permission of) the RAF 38 group website at
http://sas.raf38group.org/forum/inde...4098b2f3eee943
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Feb 16, 2016, 12:42 PM
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wizard of odd's Avatar
I'm in
Feb 16, 2016, 01:46 PM
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looking forward to this Robin
Feb 16, 2016, 03:53 PM
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eye4wings's Avatar
It's been a long time coming though hasn't it - what with one thing and another.
I have been silently watching your progress on the Comet Ken and am just dumbstruck by the technology and accuracy you demonstrate. This will be about as far as possible in the other direction as it is possible to go... Old school and low-tech!

I know both of you gents have followed Mike's thread where my own build got started, but for those who haven't it is at: https://www.rcgroups.com/forums/show....php?t=1259070
There is a load of information there that will not be repeated in this thread but once the Traplet articles are out I will put all the information I have on my build here.. including all the blunders of course.

And if I am successful in my aim of showing that everything needed to build the Stirling can be done without superhuman effort or massive investment then perhaps there will be other builds joining the thread as time goes on.

One word of warning - the March issue has been printed and I understand that the price for a not-yet-available part kit has in error been copied across from the A4 Skyhawk. This is to be corrected in a later issue.

There will now be a short intermission while we wait for the March RCMW to sell out!... I haven't seen it myself yet!

Robin
Feb 16, 2016, 06:15 PM
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I am sure you have seen this work Robin but in case others havent this is a truly remarcable rendering of a complete Stirling, not yet complete but unbelievable detail - http://sas.raf38group.org/forum/view...php?f=7&t=2279
Feb 17, 2016, 03:53 AM
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eye4wings's Avatar
Yes indeed! James and I are linked on YouTube so I have been following his work.
When his labours are complete you'll be able to print an entire Stirling in intricate detail and at any scale you fancy!
Stunning!

Robin
Feb 17, 2016, 08:06 AM
Oh no, not again!
jhspring's Avatar
So glad you are doing this thread Robin. You know I admire your design skills and ability to noodle out (relatively) simple solutions to complex engineering problems.

Regards,
Jeff
Feb 20, 2016, 05:14 PM
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Ok why was it called a Short Stirling??
jt
Feb 20, 2016, 08:32 PM
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Hi Jay,

Glad you're back on line. Built by Short Bros Aviation (Short for short ), named after the town of Stirling. Big deal b/c it was the first 4-engine heavy designed as such, paved the way for the bombing of Europe.

Interference from the Aircraft Ministry forced innumerable design compromises, including short wings, huge flaps and that ungodly complex landing gear. The latter has kept most modellers well away from it, but Robin has managed to make scale gear and flaps on his magnificent build.

Regards,
Jeff
Feb 20, 2016, 11:44 PM
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Works for me...
Feb 21, 2016, 03:22 AM
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eye4wings's Avatar
Welcome to the thread Jay,
Hope you're feeling better now.

As always Jeff is there with his history guns at the ready.

One thing that always puzzled me is why Mr. Gouge and his team stuck with the conventional tail-dragger formula for the Stirling. Having flown the half-scale prototype and decided that the full-scale version would need longer main gear because of the length of landing run they seem to me to have increased the aircraft's problems. Not only was the take-off run longer (when the aircraft was loaded with bombs) because of the increased drag of the wings at higher incidence until the tail was off the ground ( The huge area of the tailplane may have been to get earlier lift-off) but the aircraft became very sensitive to crosswinds. A number were lost to landing accidents and the prototype itself was destroyed because the brakes were locked on at touchdown.

Why wasn't the design changed to a tricycle arrangement which would have allowed much heavier braking on landing and a much speedier arrival at flying speed at take-off?
I imagine that the lack of precedent at that time would have been a key factor although one could cite the later B-24, B-25 and so on as examples of the success of the formula.
Just think of the time and effort that would have been saved in not having to winch the bombload up so far off the trolleys had the fuselage been level and low to the ground.

As it turned out the Stirling must have been safer (for the crew's survival) to land wheels up (as I have found with the model) than with wheels down in some circumstances, such as arriving home with a damaged aircraft, though it would make a mess of the bomb bays!

It seems to me that although the aircraft would have still had the same drawbacks in operations the landing problems could have been averted and many accidents avoided with trike undercarriage.
Was the possibility ever considered I wonder?

Robin
Feb 21, 2016, 08:06 AM
Oh no, not again!
jhspring's Avatar
Actually Robin, the reverse was true. The AM specs called for operation off existing grass airfields, dedicated bomber fields with concrete runways lay years in the future. Tricycle gear is not grass-friendly. Conventional landing gear has been described as great short take-off gear, but lousy landing gear (b/c of the handling problems). It gets the plane up and on the wing much more quickly than trike gear, especially on a soft surface. Gouge designed the Stirling with normal (for the time) main gear, bolted directly to the main spar, giving 3.5 degrees positive incidence for t/o but the AM decided that the t/o distance was still too great for existing grass fields so Gouge modified those huge flaps to 48% chord. The AM was still not happy and demanded that the ground incidence angle be increased to 6.5 degrees. Since the tooling for the main fuse and wing structures was already completed, the wing incidence could not be changed and the only end around was to take the original gear, bolt it to that ungainly trapeze, and lower the trapeze to get the required "sit". The dual tailwheels were b/c there was not enough clearance between the lower fuse and the tailplane spar for a single wheel to retract. The poor Stirling looks like it was designed by a committee b/c in fact, it was. The designer, Gouge, was over ridden at every turn.

At one point later in the war, Gouge tried to sell the AM a Super Stirling, which was essentially his original design - 115' span, normal size landing gear, etc. The performance was far better than the regular Stirling, but not sufficiently better than the Lanc for them to order it into production.

Whoosh (the sound of Jeff blowing the smoke from the barrels of his history guns)

Regards,
Jeff
Last edited by jhspring; Feb 21, 2016 at 08:21 AM.
Feb 21, 2016, 10:03 AM
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eye4wings's Avatar
Thank you for that Jeff! (don't holster those guns yet!)

It's easy to forget that since by the end of the war concrete runways equipped every bomber base, there was a time when only grass fields were available. The size of the Stirling was already pushing the limits of field lengths available.

It is also understandable that a committee would err on the side of convention. I struggle to think of ANY tricycle undercarriage equipped designs at the time of the Stirling's design - even in America where space was not so restricted.

I still have difficulty understanding why a greater main wing incidence at rest should help shorten a take-off run when the drag would be increased up to the time when the tail lifted to flying attitude thus lengthening the run. There would be a clear difference in the fact that once the tail was off the ground the wing would be held in roughly flying attitude by the rigging angle, whereas the trike undercarriaged type would presumably require some up elevator to rotate the aircraft (depending on rigging angles of course).

At the time of the Stirling's design what data was available that indicated that a trike undercart was unsuitable for grass fields?

Robin
Feb 21, 2016, 02:31 PM
Oh no, not again!
jhspring's Avatar
Can't fine my original article at the moment, but Wikipedia says this: the taildragger configuration has its own advantages, and is arguably more suited to rougher landing strips. The tailwheel makes the plane sit naturally in a nose-up attitude when on the ground, which is useful for operations on unpaved gravel surfaces where debris could damage the propeller. The tailwheel also transmits loads to the airframe in a way much less likely to cause airframe damage when operating on rough fields. The simpler main gear and small tailwheel result in both a lighter weight and less complexity if retractable. Tailwheels are smaller and cheaper to buy and to maintain, and manhandling a tailwheel aircraft on the ground is easier. Most tailwheel aircraft are lower in overall height and thus may fit in lower hangars.

With a couple of exceptions (B-24, P-39) trike gear was not used for propeller-driven aircraft. Even the first jets were taildraggers, they were converted to trike gear when it was realized how much damage the jet exhaust was doing to runways and taxiways.

If you have 2 identical airframes, one trike, one conventional, the conventional will be lighter and have a shorter t/o distance. Drag at low airspeeds is of far less concern than the higher coefficient of lift delivered in the nose-high attitude. This is magnified on a soft field, you want the wing taking the load (ground drag) as quickly as possible so that you can accelerate to flying speed.

FWIW,
Jeff
Feb 21, 2016, 06:12 PM
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eye4wings's Avatar
Ah, good old Wikipedia eh!
Only a couple of exceptions?
I hadn't considered fighters so hadn't thought of the P-38... but then there's the Airacobra and King Cobra and maybe the later Tigercat and Black Widow so that's 5 fighters alone without getting onto the downright weird XP-55 Ascender.
Bombers, B-24 yes, but to miss the B-29 is quite difficult... then there's the Mitchell, Maurauder, Havoc, Invader so that's 6 bombers without getting onto the also-ran B-32 Dominator or XB-19A.
Transport aircraft C4 is also fairly high-viz - and the Constellation only flew in 1943 - so we have at least a dozen trike types - admittedly all American.
Brit are far fewer. Albemarle and Libellula are the only ones that spring to my mind and the latter was only experimental.

Perhaps they were only referring to major types that had flown prior to the start of WW2?

Ah well never mind eh?
Robin


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