Spitfire Legs (Warning Picture Heavy!)

[Daniel Cox]

Hi All,

I have started this new thread because I want to more broadly cover the things that Spitfires rest upon while on the ground. My intention is to cover/discuss the main undercarriage and tail wheel units as fitted to various Spitfire aircraft. While on occasion looking more closely at the specifics of Spitfire legs.

To introduce the topic I will list the various types of struts as fitted on Spitfire main undercarriage and tail wheel units.

Please note that the following list of main undercarriage and tail wheel unit strut types is incomplete (with some obvious omissions) and may even have unintended errors. This is due to the fact that for the moment this remains a work in progress and will be amended when I have time to complete it.

The Struts

Main Undercarriage

Vickers Oleo Pneumatic Type 90273 (splined ram): Spitfire FI, FIIA, FIIB, FVA, FVB, FVB (T), FVI, PRIV, PRVII, PRXI & PRXIII.

Vickers Oleo Pneumatic Type 91244 (splined ram): Spitfire FVA, FVB, FVB (T), FV, FVC (T), FIX, HFIX, LFIX, PRXI & PRXIII.

Vickers Oleo Pneumatic Type 91244/L (torque/torsion link): Spitfire FV, FVC (T), FIX, HFIX, LFIX, FXII, PRXI, & PRXIII.

Vickers Oleo Pneumatic Type 91545 (splined ram): Spitfire FVII, Spitfire FVIII & LFVIII.

Vickers Oleo Pneumatic Type 91776 (forward torque/torsion link): Spitfire F21

Vickers Oleo Pneumatic Type 91901 (aft torque/torsion links): FVA, FVB, FVB (T), FV, FVC (T), FVII, FVIII, LFVIII, HFVIII, FIX, LFIX, FXII, PRXI PRXIII.

Vickers Oleo Pneumatic Type 91986 (forward torque/torsion link): Spitfire FVC, FVC (T), FVII, FVIII, HFVIII, FIX, HFIX, LFIX, FXII, LFXVI,

Vickers Oleo Pneumatic Type 92216:

Vickers Oleo Pneumatic Type 92238:

Tail Wheel Unit

Vickers Oleo Pneumatic Type 90356: Spitfire FI, FIIA, FIIB, FVA, FVB (T), FVC, FVC (T) FVI, FIX, LFIX, HFIX, FXII, LFXVI, PRIV, PRVII, PRXIII & PRXIII.

Vickers Oleo Pneumatic Type 91328: Spitfire FVII, FVIII, LFVIII, HFVIII, FXII, FXIV & PRXI.

A Closer Look

Spitfire Mk VIII Main Undercarriage Oleo Struts

To start I will show some examples of the various main undercarriage oleo struts as fitted to Spitfire Mk VIII aircraft.

There were three types fitted to the Spitfire Mk VIII series, they were Vickers Oleo Pneumatic types as follows; 91545 (splined ram), 91901 (aft torque/torsion link) & 91986 (forward torque/torsion link). In terms of fitment the Type 91545, 91901 and 91986 struts were fitted to FVIII and LFVIII Spitfires. While the Type 91986 struts were fitted to HFVIII Spitfires.

In terms of scale modeling Spitfires if you intend to represent a Spitfire that featured either the Type 91545 or 91986 struts you will be catered for through kit or aftermarket options. If you intend to represent a Spitfire that featured the Type 91901 struts you will have to undertake some scratch building for no kit or aftermarket manufacturer provides such struts.

The following pictures should give you some idea of what you are looking for in terms of identifying the various main undercarriage oleo struts as fitted to Spitfire VIII aircraft.

Type 91545 struts feature no torque/torsion links, Type 91901 struts feature aft torque/torsion links plus full bounce cut outs on the upper and lower link sleeves and Type 91986 struts feature forward torque/torsion links. These variations can sometimes be hard to spot, that said what one must look for is the following points: the Type 91545 struts start to taper above the top of the tyre. The Type 91901 struts don't taper above the tyre and can appear as if there's no taper or a slightly larger portion above the tyre which is related to the angle of the observer, also when viewed from the side the full bounce cut outs can be seen. You will not see the aft torque/torsion links at all because they are hidden completely by the wheel and tyre. The Type 91986 are perhaps the easiest to notice since they feature prominent forward torque/torsion links that are visible above the tyre.

This unidentified Eastleigh built JF500 series Spitfire VIII from 92 Squadron (Sqn) Royal Air Force (RAF) that first flew sometime between 19 March and 22 June 1943. As shown here was photographed at Triolo, Italy, during 17 November 1943. This aircraft is fitted with Vickers Oleo Pneumatic Type 91545 (splined ram) struts, note the taper on the strut above the tyre.

On the far left is the Eastleigh built Spitfire LFVIII JF934/A58-315, which first flew 26 August 1943 and was subsequently received by the RAAF 25 October 1943. While next to it is JG467/A58-405, which was another Eastleigh built Spitfire LFVIII that first flew 21 October 1943 and was subsequently received by the Royal Australian Air Force (RAAF) 9 March 1944. These aircraft are fitted with Vickers Oleo Pneumatic Type 91901 (aft torque/torsion link) struts, please note that the strut doesn't taper and that the torque/torsion links cannot be seen while the full bounce cut outs are just discernible.

Third in line from the camera is a Chattis Hill built Spitfire LFVIII JG3777/A58-395, which first flew 19 October 1943 and was subsequently received by the RAAF 7 February 1944. While closest to the camera in this instance is the before mentioned JG467/A58-405. Please note that all Spitfires pictured have Type 91901 (aft torque/torsion link) struts fitted and that the full bounce cut outs are prominent while the larger appearance sleeve for the torque/torsion links is identifiable.

This unidentified Eastleigh built JF500 series Spitfire VIII that first flew sometime between 19 March and 22 June 1943. This aircraft as shown here was photographed at Nettuno, Italy, 2 February 1944 with Major (Maj) 0-727434 Virgil C. FIELDS, Jr. the Commanding Officer (CO) of the 307th Fighter Squadron (FS), United States Army Air Force (USAAF) in the cockpit (Fields was killed at Anzio, Italy five days after the above picture was taken). This aircraft is fitted with Vickers Oleo Pneumatic Type 91901 (aft torque/torsion link) struts. Here again the full bounce cut out is prominent on the upper sleeve for the torque/torsion links while the links themselves are not visible since they attach to the sleeve from this sight line below the tyre.

Closest to the camera is an Eastleigh built Spitfire LFVIII MT726, was first noted at 9 Maintenance Unit 11 July 1944 and subsequently in India from 28 September 1944. This aircraft is fitted with Vickers Oleo Pneumatic Type 91986 (forward torque/torsion link) struts. Here the torque/torsion links appear prominently above the wheel well making this type rather easy to spot. It should also be noted that the wheel well and main undercarriage doors were modified to accommodate the forward torque/torsion links that would otherwise not had enough room for operation.

Close Up

Type 91901 Struts

Shown below are some pictures of mine that reveal the Vickers Oleo Pneumatic Type 91901 (aft torque/torsion link) struts in close up.

At some point in the future I will provide further information here within this discussion, until then I hope you find this post informative and appreciate what I have shared.

Cheers,

Daniel.

Edited September 10, 2013 by Daniel Cox

[Stonar]

Well I for one found it very informative and also very much appreciate you taking the time and making the effort to put the whole lot together.

Thank you very much.

Cheers

Steve

[dragonlanceHR]

Thank you for your effort.

Vedran

[Alex Gordon]

Thanks Daniel,Well worth your time and effort.

[snolep]

Daniel,

You have done some excellent work here, and later I will share some letter correspondence that Arthur Bentley and I had on just this subject back on 13 January 1979. You have not made any mention any differences between the various "C" and "E" wing and the latter's being shifted two inches forward in the "E" wing because of serious center of weight issues on the Mk.IX and Mk.VIII series. Also, there was a shift to using the Dowty designed legs as well as the difference between the five- and four-spoke wheels between the various legs also. Later.

Harold Stockton

Round Rock, TX

[Daniel Cox]

Thanks Steve, Vedran, Alex and Harold,

I'm glad you appreciate it despite my typos, there will be more later on this including looking at other struts, wheels, tyres, tail wheels and geometry as well although each addition will have to be occasionally due to the usual work and family commitments.

You are right Harold I haven't mentioned the weight issues or toe-in changes or differences in wheels and tyres etc, I will get to those and will provide more pictures of all the salient features and variations as well as further text that is all drawn from primary sources, I will also eventually add a bibliography so that others can check for themselves rather than just take my word for it if so inclined. Also I would like to thank you for your informative contribution and I'd also like to say welcome to Britmodeller you are amongst some fine company, I have no doubt you will fit right in if you have the time.

Cheers,

Daniel.

P.S. I look forward to seeing your correspondance with Arthur Bentley, I can assure you there is much I don't know about all aspects of aviation history and I am always keen to find out more.

[JOAN]

Daniel, thanks a lot for all these very clear infos ! unknow for me...

Anything about Griffon powered Spitfire ?

Is there a direct link between type of oleos and slight various angle you should see in front of the plane ? I can't recall where is the post about these angles...

Thanks for your answer.

cheers

Olivier

[Test Graham]

You have not made any mention any differences between the various "C" and "E" wing and the latter's being shifted two inches forward in the "E" wing because of serious center of weight issues on the Mk.IX and Mk.VIII series.

Harold Stockton

Round Rock, TX

Can you please expand on this? There was a two inch movement forward of the axle on the universal © wing compared with the earlier standard. This was introduced on the Mk.V, and I don't know of any other change in the structural geometry until the Mk.XX redesign. Some C wings were converted to E armament in service, so that would not require major undercarriage changes.

[Steven Eisenman]

Well it is nice that we finally have a Spitfire kit worthy of such detail comcern. Interesting undertaking, and very good.

But, is is possible for an aircraft to have gear legs of two different types? If a leg is damaged or fails, can a differnt one be put on or would both be replaced with the same type? If not, would this not have created supply problems?

[Daniel Cox]

Daniel, thanks a lot for all these very clear infos ! unknow for me...

Anything about Griffon powered Spitfire ?

Is there a direct link between type of oleos and slight various angle you should see in front of the plane ? I can't recall where is the post about these angles...

Thanks for your answer.

cheers

Olivier

Hi Olivier,

I don't have my references handy at the moment so my answer is going to be somewhat limited. Yes I will post about Griffon powered Spitfire aircraft and am considering Seafire types as well. However since I am still researching the subject, and haven't got too far yet, all I can say is that the types of main undercarriage struts associated with the Griffon powered Spitfire are as follows; 91776, 91901, 91986, 92216 & 92238.

As to there being a direct link between the oleo struts and there geometry, I think it best to say I don't know, I have read some things in secondary sources on this and vaguely recall reading about mods in some primary source documents that relate to toe in changes and what Graham Boak and Harold Stockton have made reference too. For now though since I don't want to give you the wrong information I can't really comment until I've done more research. That said I believe their are a few others on this forum who can probably answer this better than I can at the moment.

For the moment I am at the stage of mostly collecting information, which so far has involved copying a lot of primary source documents, starting to examine some surviving struts, trolling through and seeking out prints, negatives and or hi-res copies of them for examination, starting to contact a few curators and others relevant persons and organisations that may have struts, wheels or anything else of interest etc or can otherwise point me to people who do so I can visit them to examine what they have. Most of the information I have collated so far revolves around the following Spitfire types, V, VIII, IX/XVI with some information on the XII, XIV & I/II and much less and sometimes almost none on other Spitfire iterations.

While I'm looking through what I have over the next few weeks, I will be mindful of your questions and see what I can find out to answer your question accurately.

Cheers,

Daniel.

[John Aero]

The angle referred to is the leg rake when viewed from the side not the front. IIRC the Mk.21 track angle was different. Changes were also made to the axles affecting the angles the wheels had with the ground. The 2" movement was done by fitting new pintles. If I have Steve's question right,to fit two differing types of leg (compression rates) would be asking for serious ground handling problems.

John

[JOAN]

Daniel, thank you so much for your answer. Your work is invaluable.There is so many books on the subject and so few about the technology. My interrest in aviation is exactly with this angle. I think your work must be write and kept somewhere...( my opinion ). thanks again for sharing with us. My humble and poor original prints collection at your service sir.

John, thank also for your comments.I didn't recall and found a previous post about this point...How do you know such amount of technical infos !!!

Guys your knowledge on the subject is totally amazing !

olivier

[Edgar]

Well it is nice that we finally have a Spitfire kit worthy of such detail comcern. Interesting undertaking, and very good.

But, is is possible for an aircraft to have gear legs of two different types? If a leg is damaged or fails, can a differnt one be put on or would both be replaced with the same type? If not, would this not have created supply problems?

There are instances, in some A.P.s, which permit the occasional "mix-and-match," but they are few-and-far-between, and would need copies of all of the A.P.s (which I don't have) to make a comprehensive list.

To answer another statement (above,) there was no difference between the u/c leg rake on the C & E wings; it changed, by 2", between the Va/b & Vc, and remained constant until the 20-series. In the leaflets about c to e conversions, mention is only made of the change to the plumbing, and nothing about the legs at all.

Edgar

[Test Graham]

If the difference was just in whether the anti-torque link was at the front or the back, or missing altogether BUT the geometry and compression rates were the same, then there'd seem to be no handling problem. There might however be a problem on retraction - I recall that one of the link positions requires a modification to the well and door and can be identified by the altered door?

Edited June 26, 2013 by Graham Boak

[Edgar]

The front-fitted torque link caused a triangular piece to be removed at the "corner" where the leg tunnel met the wheel well, but it was supposed to be replaced if the aircraft ever went back to using legs without the links.

[Daniel Cox]

Hi All,

You're welcome Olivier it's my pleasure, likewise thank-you for showing off your wonderful collection of images. Thank-you also to John, Edgar and Graham I appreciate your contributions.

One thing also worth considering regarding the usage of different main undercarriage struts is the fact that the strut pressure for the same type of strut would vary depending on the Spitfire variant they were fitted to. For example the Type 90273 strut commonly associated with the Spitfire FI had a strut pressure of 420lbs/sq" whereas the same strut on the Spitfire FVB had a strut pressure of 455lbs/sq". Likewise the Type 91901 (aft torque/torsion link) strut when used on the Spitfire FVIII used a strut pressure of 510lbs/sq" while on the Spitfire FIX it required a strut pressure of 465lbs/sq". Alternatively the same before mentioned Type 91901struts on the Spitfire PRXI required strut pressures of 510lbs/sq" on the starboard side with 465lbs/sq" on the port side. Then there where different tyre pressures on different tyres which were often different between strut and variant of Spitfire. Then the different types of brakes, wheels, locking pins etc.

I am aware of strut types being changed during a Spitfires service life for example there is ample evidence of some Spitfire VIII aircraft being delivered with Type 91901 struts that subsequently were fitted with Type 91986 struts later in their operational careers. This also applies to other Spitfire variants as well.

Anyway it's time for me to go so good night all.

Cheers,

Daniel.

[John Aero]

That's interesting, regarding the differential oleo pressures on the PR.XI. I presume that this is due to the high torque effect on a very heavy a/c on takeoff and compressing the right (Stbd) leg even more. If I've got it right, changing the angle of the leg forwards by two inches would have two effects. It would move the C of G back and also induce a greater castor force(trail angle on wheel vertical cenre) on the wheels, keeping the aircraft straighter. (Culled from wheel geometry in my 1930's Motor Engineering book)

John

[Edgar]

A former 1940-era erk told me that they had the port oleo leg stiffer than the starboard, to stop the wingtip hitting the ground on start-up; as far as I can tell, the first Spitfire to have the 2" forward rake was the Mk.III, probably due to the longer Merlin XX making a nose-over more likely (like the Hurricane, the XX made the Spitfire fuselage 4" longer.)

Edgar

[gingerbob]

John, I don't follow your "greater castor force"- it may be something better shown by graphics, or maybe I just am misinterpreting. Moving the wheels forward would tend to de-stabilize ground tracking (the back end would have more tendency to want to come to the front). Toe-in is another way to combat this inherent tendency of taildraggers, and the Spitfire did also monkey with that at some point, though not necessarily for this reason. Perhaps the Spit's behaviour was benign enough that it wasn't considered an issue. It would also put more weight on the tailwheel, but it doesn't move the C of G back, just the distance between C of G and main wheels. More to the point, it "lightens" the nose, so that the aircraft has less tendency to tip forward- but putting the Merlin 61 engine a little further forward will have pretty much eliminated that gain!

Steven, a preserved XIV had come to the team who restored it (in Belgium) with two different types of gear leg, but that doesn't necessarily mean it was so-fitted when in service.

Edgar, yes, the Mk.III introduced the forward shift of the main gear (change of angle), but only the second prototype, not, as is often stated, the first prototype. (It was in mind, though.)

bob

[nicholas mayhew]

What a great thread

Thanks for posting all this info!

[BD1944]

Hi, gang: Bri Derbyshire here, last to hear about everything as usual.

Just got involved with Eduard's 1/72 Spit VIII and its U/c choices. Of course all my gen (up to and including Uncle Trevor's opus) lists only 3 types of Spit' U/c - Vickers splined, late C/Brom fwd links, Mk.21-series aft links. Naturally I turned my nose up at Ed's aft links ... but thought I'd better check. I found all the 2012 stuff - but of course all the photos have been deleted. Still, I'm OK with the hypothesis that there was an interim, flat-scissor aft-link conversion kit to beef up the splined leg, as illustrated on the bright greeny-blue leg from Argentina (which I can't find now.)* I found a pic of a door (Spits in preservation, Scale Models, 10/69 p.16) with a small pip on the aft segment, which I thought might be relevant, but the only contemporary Spit I can find with said pip - for sure  - is "Lonesome Polecat." So I'm still at sea.

 

I'd be most grateful if anyone who posted relevant pics on this thread could contact me, with a view to furthering my education.

 

Regards, BD.

 

* OK, found it - B.

Edited May 30, 2018 by BD1944