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Posted

I have been led to believe  that the Tailplanes on the Lysander were different on the Mk II version. Can anyone clarify?

Posted

The latest edition of Scale Aircraft Modelling has an article on the Lysander and a colour conundrum piece, the only Mk2 difference stated is a shorter straight sided engine cowl.        😉

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Posted

I have trouble understanding why a change would have been necessary for the Mk.II specifically, but I can see how a change from then on might have been done.

Posted

Both the 4+ and the Aeroplane Special plans (the latter by  GR Duval so almost certainly ex-Aeromodeller/MAP from around 1958) show this difference.  Flight's 1938 cutaway shows round tips: the slightly squared tips are described as Mk.II and some Mk.I by 4+, simply as Mk.II by Duval.  Photos of early Mk.Is show the round tips of the prototypes, but others appear to be squared off.  I've yet to uncover a photo of a Mk.II appearing round - but the matter is slightly confused by the original round tip appearing slightly flattened at the far tip in some views.  I suggest this is because it wasn't a simple semi-circle but a flatter curve in this area.  It seems as though Westland had to do a bit of trimming of the horn balance following flight trials and perhaps service experience, but I would assume that later marks had the later tailplane, given the lack of direct evidence.  Unless of course you know better.

 

Later today I may be able to get to the Putnam Westland book, which may say more.

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Posted (edited)

I saw that drawing previously. The MkIl tailplanes are less rounded. Then I see this sprue shot. 

What do you think? Has Airfix inadvertently supplied MkIl tailplanes, or is the drawing wrong? 

sprue1.jpg

Edited by noelh
Posted

My comment above might fit.  There's a view almost head on of the prototype showing a flatter tip than the drawing (which I believe is the Duval one) but these things are subtle.  Maybe Airfix might have overdone the flattening a little, or perhaps there were development changes.  I think I'd be inclined to make the leading edge a little more rounded and accept that - but these things are up to the individual modeller.

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Posted

Hi

      the 4+ drawings are good, i was told they contacted westlands for research/ info in the archive

  cheers

     jerry 

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Posted

So, I suppose they're usable for a MkIl. For a MkI a little bit of fettling will round it off, as Graham suggests. 

 

So all we need is a new cowling and engine for a MkII. 

 

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Posted

The conversation thus far shows why we need some actual documentation to establish the actual facts of the situation!  I'd seen the drawing, too, but that's only "circumstantial evidence".

Posted

Ideally, although 4+ claim they did, and appear to match photos at least fairly well.

 

We can consider why they would change.  Two possibilities come to mind,  The first is a handling difference between the Mk.I and Mk.II, which can only be due to the engine.  In which case there should be no modified tailplanes on Mk.Is, or Mk.IIIs.  Or some deficiency was found in service and the tailplanes altered during Mk.I production.  In which case the Mk.III will have the later tailplane.  So photos of Mk.III tailplanes please.

 

EDIT: The Putnam is of no help in this respect, other than discussing Davenport (the designer) being unhappy with the landing trim and particularly with the variable tailplane solution, but being over-ruled by Petter and the production side eager to get it into service.  There are accounts given of the problems that then arose, but nothing on solutions (presumably more emphasis during training?)  Of course, this may not be relevant to the fairly small effect of the tailplane change...  The book does include photos of some early aircraft with a flatter tip parallel to the flight axis, not shown on either plan.

 

I'm no specialist on handling, but to me a shortage of trim requires a larger tailplane or longer fuselage, which would certainly have delayed production.

Posted
23 hours ago, noelh said:

So, I suppose they're usable for a MkIl. For a MkI a little bit of fettling will round it off, as Graham suggests. 

 

So all we need is a new cowling and engine for a MkII. 

 

SBS just released a nice resin set with Mk.I/Mk.III engine and cowl. Perhaps if we all ask them VERY nicely they could be persuaded to do a Mk.II engine and cowl.

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Posted

Col Ford's pointed me at this discussion, as I'm revising my Lysander book. I can say we'll be able to, I hope, give a definitive answer, in a week or so. My colleague, who's advising me on the topic has said he has sets of copies of original Westland Aircraft drawings, so I'll ask him. Unfortunately he's not where the drawings are right now, so we'll have to have a little patience!

 

In the meantime some facts. The Mk.II was equipped with the sleeve-valve Bristol Perseus engine, vs the Mk.I and Mk.III having the Bristol Mercury. The main differences as far as modellers are concerned is the Perseus was a slightly larger diameter, slightly longer engine, by a couple of inches in each case. The Mk.II can be distinguished visually by the lack of teardrop bumps on the cowl, the lack of a cutout in the cooling gills in front of the cockpit, because (and this is hard to see) the cowl is actually shorter (in chord). The aircraft are the same length overall, because the engine is positioned further forward on the airframe, the prop being positioned in the same location. As a result, the Mk.II has slightly more panel visible fwd on the fuselage, compared to the Mk.I / III.

 

(Another fact is there are no Mk.II Lysanders surviving. Everything we have is Mercury powered.)

 

There seems to have *possibly* been some variation in *some* Mk.I and possibly Mk.II tailplane tips. Why? Don't currently know. I don't believe there were issues specific to Mk.II that were addressed by changing the tailplane tips - the c of g and power are unlikely to have been addressed that way. But rather than guessing further, I'll try and report back with data.

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Posted

The first batch of Lysander I production began in May 1938, finishing in December with mark II taking over until May 1940, mark III production began in June 1940, IIIA in December.  In addition there was a mark I built for France in July 1939, 35 mark I for the RAF September and October 1939, 19 for Finland and Egypt January and February 1940 then finally 68 for the RAF May to July 1940.  Not quite a straight progression of mark numbers.  RAF Mark I batches, first L4673 to L4738, second P1665 to P1699, third R2572, R2575 to R2600, R2612 to R2652.

 

Delivery date wise the second mark I batch is between the mark II serials ending N1320 and those starting P1711, the third mark I batch is between the final Lysander II serials R2025 to R2047 and first mark III serials starting R9001 (R8991 to 9 to Finland in February 1940, R9000 to Egypt).  In other words, apart from export orders, the Lysander were built in RAF serial order, switching I to II, back to I, back to II, back to I, to III.

 

RAF contract card notes, from the first contract 55425/36 for mark I, 3 converted to III TT, 1 converted to II, then another note says from the first 3 contracts 555425/36, 611314/37 and 762830/38 for 287 aircraft, 12 converted to III TT, 4 to III, later again is a summary of 41 conversions, 5 I to III TT, 16 II to III, 20 II to III TT, with 18 conversions from the original contract.  L4674 converted to II, to be fitted with twin cannon.

 

Canada built mark II September 1939 to January 1940, March, May and November 1940, January to April 1941, mark IIIA March to October 1942, retained in Canada

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Posted (edited)

Very major thanks to David Upton for supplying a set of Westland works drawings promptly!

 

Unfortunately he doesn't have a full set to hand, but here's the Mk.I / Mk.II, as per Westland. Obvs there may have been amendments. The drawing above posted by @warhawk show a round tip (one continuous semi-circle) that match what we have in the other drawings for the early Mk.I / prototype, and as we've seen the Mk.III is 'chunkier'. Not sharing the other drawings at this stage as I suspect they aren't production but part of the notorious trim challenge attempted solutions.

 

I'm not been able to match off the research, as yet, but this does at least, answer the OP question! Stay tuned if we can advise further, we will. (And thanks to the shade of the late Fred Ballam of Westlands archive.)

 

Lysander MkII tailplane

 

Edited by JDK
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Posted

Interesting - to my eyes at least, that's yet a different shape; if the Duvall drawings are not distorted, they show a distinct outward "kink" of the tailplane directly in front of the elevator tip.

Posted (edited)

So using the data from @Geoffrey Sinclairand information from @Graham Boakcan we assume that some early MkIs and MkIls had the rounded tips? But at some point it was changed to the more squared off tips. There must have been a a point of transition. But are there any photos of non prototype Lysanders with rounded tips? 

Edited by noelh
Posted

My current *hypothesis* is:

 

The design started with a semi-circular tip

 

There was a LOT of trials to sort out the trim issue. (THAT is a fact)

 

Early ones probably had that rounded tip, changing at a point that's not the same as a Mk change

 

There was definitely a skewed two-radius curved tip version seen on Mk.III and Mk.II in photos

 

There MAY have been two versions of a skewed tip (there are certainly drawings indicating different radii to that noted in my drawing above, the differences being small however)

 

I'm stopping there while we see if we can get more primary data, which I'll share when I can.

 

Hope that helps, feedback keeps the engagement worthwhile!

Posted
On 2/3/2025 at 4:10 AM, Graham Boak said:

I'm no specialist on handling, but to me a shortage of trim requires a larger tailplane or longer fuselage, which would certainly have delayed production.

There was no 'shortage' of trim, the issue was if trimmed for landing, a 'go around' required SMALL and gradual increases of power while frantically winding off the landing trim.

 

If you took off with landing trim set, or put power in quickly (say, because you were running out of field) you couldn't push forward enough quickly enough to avoid a trim induced climb, stall and crash.

 

That's why a final check was to double check take-off trim; and why there's sometimes the markings on the fuselage by the leading edge of the tail so ground observers can see the trim setting.

 

The argument wasn't resolved, production intervened and the Lysander remained with this significant risk throughout. In context, such a risk wasn't unusual for a WWII era combat type; all twins had a graveyard zone for engine failure on take off for instance.

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Posted
10 hours ago, noelh said:

So using the data from @Geoffrey Sinclairand information from @Graham Boakcan we assume that some early MkIs and MkIls had the rounded tips? But at some point it was changed to the more squared off tips. There must have been a a point of transition. But are there any photos of non prototype Lysanders with rounded tips? 

Not quite what I said.  I saw photos of examples with flattened tips, but apparently not with the significantly angular shape shown in the drawings.  I would not assume that any Mk.IIs had rounded tips, and I'm uncertain whether any Mk.Is did, or just examples with only slightly flattened tips which are difficult to distinguish in photos from fully rounded ones.

6 hours ago, JDK said:

There was no 'shortage' of trim, the issue was if trimmed for landing, a 'go around' required SMALL and gradual increases of power while frantically winding off the landing trim.

You are describing the final standard, I was describing the first flight standard which did not have the adjustable tailplane.  See James (Putnam) pp236,237.

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