Hawker Hurricane Mk X Information Sought

It is possible that the material was produced in Canada, but my guess would be that CC&F used a US source. Canadian aircraft production was next to nil prior to WWII, and the US was using 4130 for many designs, so I presume CC&F would have used a US supply source from just “across the line”. Still working on documentation to support Mr. Carmichael’s comments.

I have discussed the matter with someone who interviewed Jim Carmichael (Can Car) on this very topic. When asked what CC&F used for their Hurricane production, his answer was “whatever we could get our hands on”, which turned out to be 4130 as a substitute for the T.50.

A fascinating anecdote which would explain many questions, and of course to find some original documentation to verify this would be gold.
Where in the US or Canada could you buy cold drawn aircraft tube from in 1940-1 ?

Does this mean you’ve tested the piece of centre section spar that I sent to you?

Ron, indeed the section was tested in June and results posted on #23 here :
http://forum.keypublishing.com/showthread.php?129241-Hart-Hind-Bulldog-Wapiti-Atlas-Siskin-Hurricane-amp-others-steel-testing&highlight=

I try and post up results as soon as I can on the forum to make this information available for all – as a simple courtesy I reflect I should have directly contacted you at the time to let you know this information was posted and I am grateful that you sent the sample in. Often I find that testing creates a whole new range of questions and it is this sample that has opened up the material substitution line of query for CCF Hurricane, so a very valuable piece of metal carrying an interesting mystery.
Ed

I have also tested known CCF Mk X centre section spar remains which report manganese alloy (DTD 138) spar booms, obviously different to the British made aircraft using nickel chromium booms (S88c). Subject to confirmation, the theory is that CCF used local materials for Mk X that were different to materials used in the UK. The link to your question is whether a RCAF AP would specify DTD138 for centre section spar boom repairs, which would be delightful to confirm, or a later RAF AP covering Mk X would do the same.

Does this mean you’ve tested the piece of centre section spar that I sent to you?

Cheers,

Ron

P&P,

I’ve been doing some digging on this recently, and while I’ve yet to locate specific CC&F documentation, I have discussed the matter with someone who interviewed Jim Carmichael (Can Car) on this very topic. When asked what CC&F used for their Hurricane production, his answer was “whatever we could get our hands on”, which turned out to be 4130 as a substitute for the T.50.

I don’t expect that transport would be too happy with a 3rd party quote as a reference for material substitution, but it was interesting to hear nonetheless. The search continues for CC&F archives, which appear to have been broken up into many pieces and spread between Government, corporate and non-profit organisations throughout Canada.

Ian,
I have access to a Hurricane I Repair & Maintenance AP which predates CCF Hurricane X. In the case of repairs to centre section spars, made from BS S88c nickel chromium alloy, repair patches of S88c or DTD 166 stainless (same material used in the fuselage fish plates) are specified.

I have also tested known CCF Mk X centre section spar remains which report manganese alloy (DTD 138) spar booms, obviously different to the British made aircraft using nickel chromium booms (S88c). Subject to confirmation, the theory is that CCF used local materials for Mk X that were different to materials used in the UK. The link to your question is whether a RCAF AP would specify DTD138 for centre section spar boom repairs, which would be delightful to confirm, or a later RAF AP covering Mk X would do the same.

In thinking through this information I have the following reflections :

Repair & Maintenance APs were practical documents focused on the quick return to air of battle damaged aircraft. Therefore materials reasonably at hand of a repair unit would be specified. The great advantage of DTD 166 was its presentation as sheets of work hardened material with a strength of 50T minimum that could be work hardened to 65T and used to repair a wide scope of the Hurricane structure. I have seen in lists of equipment for Maintenance units dealing with Hart biplanes in the 1930’s in Iraq sheets of DTD 166, and it can be defensible to accept that this practice continued with the Hurricane, as the argument in the buildup to 1939 was there were trained fitters for this type of aircraft and they should be built in preference to the monocoque aluminium Spitfire types. There is no mention of sheets of S88c, which is a corrodible material which can only be supplied as heat treated coil, far less practical to a front line maintenance unit. I draw the conclusion that repairs using S88c where based on salvage material from written off aircraft.

To introduce a new material, DTD 138, into the mix would be an unwelcome complication in procurement and engineering management. It would make more sense for a CCF Mk X to be repairable with DTD 166 or salvaged S88c. They key is the performance values of this material, in that work hardened DTD166 would aquire strength values of 65T, in common with 65T S88c and 65T DTD138.

Where CCF did re-engineer the Mk X Hurricane structure, they would have taken care to meet the same strength values using DTD 138 as the original S88c. In other words spars would be absolutely interchangeable, and there would be no complication in a frontline maintenance unit in blending CCF parts with UK parts. In this respect the simple solution would be to allow the maintenance unit to rely on existing APs, without confusing them with questions about materials. If this is true then no maintenance AP will come to light that specifies DTD 138, though in the literature of the 1930’s DTD 138 is listed as a typical spar material.

I think today, that most folk would not recognise the use of DTD 138 in Hurricane construction. If the logic stands, that it is directly interchangeable with materials more commonly understood to be used in Hurricane construction, then it is largely just a curiosity. It does suggest, however, a considerable effort to re engineer the Hurricane structure in Canada that would be a fruitful body of work to rediscover. Consistent with this are the use of SAE 4130 spar liner tube in the CCF product rather than 3% nickel alloy T50 in the UK product and United States sourced EN 8630 nickel-chrome-moly fuselage tubes in the CCF product rather than 3% nickel alloy T50 in the UK product.

This is an example of wartime substitution which could greatly inform future restoration work concerned with strip steel and pin jointed construction. Clever Canadians.