A question regarding early Spitfire seats...

[Jim Kiker]

Hi all,

Like many of you I am currently working on a Spitfire project. I am building the Tamiya 1/48 scale Mk I kit into a PR IA. Actually, I have read many references and spoke before about this project, and there seems to be several different stories as to the PR IA designation, versus PR I. In any event, I am doing N3071 which flew the first photographic sorites conducted by camera equipped Spitfires. Thanks again to Colin S-K, Nic, Graham, Wally, and a host of other boffins for their assistance!

Given the photographic evidence, N3071 appears to me to have been built to the Mk IA standard. I note especially the three-bladed De Havilland prop and spinner, and the data as given in the Spitfire bible. Remember too that this a/c and her sister were sent to Cotton's unit in mid-October, 1939, and the initial PR mods completed within a few weeks. So the question I still have is, would this a/c be equipped with the very early metal seat, or a Tuffinol (spelling?) one? My theory is that N3071 would have had the Tuffinol seat, and that perhaps it was one of the things that went with the Mk IA series of Spitfires. Right or wrong? Can anyone shed some light on this?

Many thanks in advance, and I hope all of you have a healthy and happy New Year!

Cheers, Jim

Edited December 30, 2009 by Jim Kiker

[Edgar]

Metal (could be green, but the Patrick Stephens authors found one, going by their text, that was black in the IWM's R6915.) The plastic (not Tufnol*, or Bakelite**, whatever the "experts" tell you) seat was planned for, in 1938, initially for Castle Bromwich, exclusively, but there were huge problems with its (lack of) inherent strength, and it wasn't passed for use until May, 1940. Although the seat could be changed over (relatively, it's a multi-handed job) easily, it's a bit unlikely in your example.

Edgar

* Tufnol, as a company, existed before the war, in Glasgow, but the seat was manufactured by Aeroplastics Ltd. (also in Glasgow.) Tufnol make a resin/paper material now, and Aeroplastics no longer exist, but I've been unable to find out if Tufnol took them over.

** Bakelite is a moulded material, of a granular type of material, which needs precise temperature control and tremendous pressure for moulding. A friend made instrument cases from Bakelite, around 30 years ago, and says that the size of the seat would have made consistency of the temperature impossible, together with the huge increase needed in the pressure.

[AnonymousDFB1]

Jim, Sorry to derail your thread a little, but do you know what plastic Edgar? I've always read that it was Bakelite but knowing the strength or lack of I have always been dubious. I remember working with Tufnol as a young trainee engineer and again can't see a seat being made out of it!

[Troffa]

As pointed out a couple of years ago there is reference to a "Bakelite" seat in the Seafire AP, AP2280, although this may just be a case of as "Hoover" became the term for all vacuum cleaners, so "Bakelite" was the generic term for all resin impregnated cloth or particle moulded items, but one can see where the Bakelite proponents (Or even "experts") get their evidence from if its in official contemporary documentation.

Original thread here:

http://www.britmodeller.com/forums/index.php?showtopic=3165

[StephenMG]

Mish - not actually 'plastic' as we know it now but an 'engineering plastic' called SRBP (Synthetic Resin Bonded Paper). It's basically layers of paper impregnated with resin to produce a 'plastic' type material. This method of manufacture means that it can be made in a mould - seat shaped for example! It is characteristically a light red-brown colour - hence the colour often seen in old aircraft seats. SRBP is the generic name for it, trade names are Paxoline, Lamitex etc..

SRBF (Synthetic Resin Bonded Fabric) is a similar material which used fabric instead of paper in it's structure.

The same basic style of seat and SRBP material was used in countless aircraft - Spitfire, Hurricane, Hornet, Vampire for example. They even appeared in some Canberras. SRBF was extensively used in making things like instrument panels and heel plates on cockpit floors etc. - good examples of both can be seen in the Mosquito, and most commonly as insulators and circuit board material in the electrics.

The reason people refer to this material as Tufnol is because it's a famous brand name - a bit like referring to any vacuum cleaner as a Hoover or any clear plastic as Perspex. Personally I always use generic SRBF/P because it's much cheaper than paying for the brand name. So technically Edgar is right, it's not correct to refer to the material as Tufnol, but it's SRBP. Bakelite is a completely different material and is quite brittle. It would be useless for making aircraft sets but the name does get used, even cropping up in official documentation sometimes. (Edit: Troffa - you beat me to it!)

Edited December 30, 2009 by StephenMG

[AnonymousDFB1]

Thanks guys I know exactly what you are talking about.

[Steven Eisenman]

Interesting in that article, bakelite is in lower case. Where as Bakelit was a registered mark, IIRC.

Also, as I recall, Bakelite was fairly brittle, and could crack on impact.

There was also the mixing of fiber or wood pulp and resin cast into a seat. This appeared int e P-39.

I believe the general term for the mixing of "product" and resin was phenolic resin products.

http://en.wikipedia.org/wiki/Phenolic_resin

[lufbramatt]

just to clarify, is this the correct pattern metal seat for a mk1:

and this is the later (mkV?) paper/resin seat?

and the flare carrier at the front, was that there from the start? ie present on a mk1 and not a later addition?

[Steven Eisenman]

For those that want to really do the metal seat....

[Edgar]

just to clarify, is this the correct pattern metal seat for a mk1:

and this is the later (mkV?) paper/resin seat?

and the flare carrier at the front, was that there from the start? ie present on a mk1 and not a later addition?

No, no, and no.

This is the early metal seat; note there's no cut-out in the right side (that came later; I believe to stop any possibility of the Sutton strap fouling the raising/lowering lever.) Not visible from this angle, but the early seat had no cut-out (handhold) in the backrest, either; the first oval cut-out was in the newly-fitted armour plate. The cartridge carrier was meant for the Seafire, but appeared on various Marks, at various times; although removal of the seat is a swine of a job (the carrying framework has to be at the bottom of its travel, or the seat jams against the bulkhead as it's lifted,) either seat could be fitted. A Very pistol was planned-for, from the start, but the stowage was deleted 29-9-37; the Seafire brought it back.

That later plastic seat, of yours, is a late/middle-war variant, since it has the lozenge-shaped indentation for the dinghy's airbottle (most uncomfortable to sit on.) Early pilots just had to make do with a Mae West.

Note that the metal seat (which I photographed only this year) has been modified to take the post-war QS harness; I could go on, ad nauseam, about the mythical "Q" harness, on Spitfires, but this is not the time, or place. Suffice to say, stick with Sutton harnesses, and don't shove the straps through the backrest, unless you're working on a (very) late/late war Mark.

Edgar

[Jim Kiker]

Thanks, everyone!

Just what I needed to know, plus a lot of additional information that will prove useful down the road. As usual, here at BM!

Cheers, Jim

[lufbramatt]

many thanks edgar, excellent info!

i wasnt sure about the flare rack, hence me asking the question

[Steven Eisenman]

Edgar;

Is this a cross-over point? Ring and bead site and you can see the cartridge rack.

[Steven Eisenman]

More pix I found in my files...and HRH the King!

[Edgar]

All three of those are very early, with the top two having the original hand-pump method of u/c retraction, and the bottom one photographed in pre-armour days (looks as though the seat's been removed, as well.) Note the "ring-pull" door release; reminds of the first Mini car door!

The top two could well stem from the time that the Very pistol was still planned for use. I have to wonder at the middle photo; with the "bicycle chain" visible at the rear of the control column, and the oxygen regulator missing from the top left of the panel, it looks as though this one was undergoing maintenance (would explain the odd "cushion" in the seat, as well.) It's certainly very early, since the signalling switch box, remote contactor, and gunsight bulb holder are not fitted (I wonder how many had chrome tubing for the u/c handle, too?)

I shall have to revise my feelings about the hole in the right side of the seat; I've found the cockpit photos, from the Mark I manual, and, although it has the lever-style u/c retraction, the pedals are still single-bar, and the hole is clearly visible, so it came in earlier than I first thought.

One item that I did forget; the "kink" in the left side was lined with a piece of (probably basil) leather, which wrapped over the edge, and also encroached about 6" onto the base. This was to stop the metal of the seat chafing the ripcord.

Edgar

[lufbramatt]

I have to wonder at the middle photo; with the "bicycle chain" visible at the rear of the control column, and the oxygen regulator missing from the top left of the panel, it looks as though this one was undergoing maintenance (would explain the odd "cushion" in the seat, as well.)

theres also what looks like two locking bars to centralise the control column, i guess they were setting the tension on the cables to the control surfaces or something like that.

ive got a 1940's copy of the mk2 spitfire operators manual, i'll have a look at that next week when i get home, and also have a look for info on the flare cartridge rack.

[gingerbob]

"So I tells meself, yer Majesty, "Why, Tom, that looks just this far from matching Humbrol 90!" so I popped open a tin, and had it good enough for a Royal inspection 'fore you could say "Bob's your uncle."

[Nick Millman]

"So I tells meself, yer Majesty, "Why, Tom, that looks just this far from matching Humbrol 90!" so I popped open a tin, and had it good enough for a Royal inspection 'fore you could say "Bob's your uncle."

Excellent! The mustachioed officer is undoubtedly holding up an early tin of Humbrol!

But Steven, in the interests of monarchic pedantry, it is HM The King not HRH The King!

[Terry McGrady]

Excellent! The mustachioed officer is undoubtedly holding up an early tin of Humbrol!

Yes Nick , but it isn't Humbrol its a sample of Dupont Sky Grey

:):)

Happy New Year

Regards

Terry

[jenshb]

not actually 'plastic' as we know it now but an 'engineering plastic' called SRBP (Synthetic Resin Bonded Paper). It's basically layers of paper impregnated with resin to produce a 'plastic' type material. This method of manufacture means that it can be made in a mould - seat shaped for example! It is characteristically a light red-brown colour - hence the colour often seen in old aircraft seats. SRBP is the generic name for it, trade names are Paxoline, Lamitex etc..

SRBF (Synthetic Resin Bonded Fabric) is a similar material which used fabric instead of paper in it's structure.

The same basic style of seat and SRBP material was used in countless aircraft - Spitfire, Hurricane, Hornet, Vampire for example. They even appeared in some Canberras. SRBF was extensively used in making things like instrument panels and heel plates on cockpit floors etc. - good examples of both can be seen in the Mosquito, and most commonly as insulators and circuit board material in the electrics.

The reason people refer to this material as Tufnol is because it's a famous brand name - a bit like referring to any vacuum cleaner as a Hoover or any clear plastic as Perspex. Personally I always use generic SRBF/P because it's much cheaper than paying for the brand name. So technically Edgar is right, it's not correct to refer to the material as Tufnol, but it's SRBP. Bakelite is a completely different material and is quite brittle. It would be useless for making aircraft sets but the name does get used, even cropping up in official documentation sometimes. (Edit: Troffa - you beat me to it!)

An interesting discussion as it seems to challenge something that "everybody knows" - the material of the Spitfire seat. I too have held the belief that the plastic seat was Bakelite. The designation SRBP only tells part of the story however - it basically says it's a composite type material, but as we know, there is a wide range of composites. Common to all composite materials, it has a matrix (the "glue") and the reinforcement (the "fibres"), and from the description of SRBP, we know that the reinforcement is paper. However, what substance is the matrix? Entering SRBP in Wikipedia will redirect you to FR-2 that is a material used for making printed circuit boards. The description of FR-2 is a "synthetic resin bonded paper, a composite material made of paper impregnated with a plasticized phenol formaldehyde resin".

http://en.wikipedia.org/wiki/SRBP

Bakelite is just that - "...a thermosetting phenol formaldehyde resin, formed from an elimination reaction of phenol with formaldehyde,..."

http://en.wikipedia.org/wiki/Bakelite

Although pure Bakelite is brittle, the reinforcement will add strength to the material (as in any other composite), and indeed further down the page, you will find the description

"LINEN REINFORCED PHENOLIC NEMA L per MIL-I-24768 TYPE FBI NEMA LE per MIL-I-24768 TYPE FEI Good mechanical and electrical strength. Recommended for intricate high strength parts. Continuous operating temperature 250°F. "

Could therefore the seat of the Spitfire be made from Linen reinforced phenolic? It looks appropriate to the purpose (i.e. make a seat) for me. Could this also be the reason why bakelite is mentioned in official documentation? That the material is a mix of Bakelite and either paper or linen?

Jens

[StephenMG]

Could therefore the seat of the Spitfire be made from Linen reinforced phenolic?

Yes, that's exactly what it is, except it's reinforced with paper (making it SRBP) rather than Linen (which would make it SRBF).

"Phenolic" resin is a bit of a general term covering the 'resin' part of a number of materials. So, for example Bakelite is made from phenolic resin and wood flour as a filler, SRBP (e.g. trade name Paxolin) is phenolic resin and paper, and SRBF (e.g. trade name Tufnol) is phenoic resin and a woven cloth. As another example the 100 gallon drop tanks used on the Hawker Hunter were made from phenolic resin reinforced with asbestos. These are sometimes referred to as "plastic" tanks in the same way that the SRBP Spitfire seat is often referred to as "plastic".

So a Spifire seat IS made using the same resin that goes into Bakelite, but with different reinforcement , i.e. paper. It's easy to see where the confusion comes in, but it's not actually Bakelite, it just happens to share the same resin as Bakelite.

[jenshb]

Now that resin you're describing, isn't that just pure Bakelite? As mentioned here

http://portal.acs.org/portal/acs/corg/cont...e6-de26a77ee9ab

"The pure Bakelite resin was lovely amber, and it could take other colors as well. Unfortunately, it was quite brittle and had to be strengthened by "filling" with other substances, usually cellulose in the form of sawdust. After filling, all colors came out opaque at best and often dull and muddy."

The Bakelite does not have to have wood fillers to be called Bakelite - the basic material would necessarily have to be invented before properties can be explored and improved in by adding various fillers. Polypropylene is still polypropylene even if you add talc, however, each manufacturer will have their own tradename for what are similar materials. Phenolics is a designation for a group of plastics that Bakelite is a part of, so that name is not really a precise name for the plastic used to make Spitfire seats. From the wikipedia article, the proper name (say analoguous to polycarbonate) is polyoxybenzylmethylenglycolanhydride...Bakelite rolls easier on the tongue:)

Jens

Edited January 5, 2010 by jenshb