Hurricane Fuselage- why was it bolted together?

If you have a read through Hawker Aircraft by Putnam it claims that the design had some roots in the Fury design, it also states “the aircraft combined the well-proven tubular metal cross-braced fabric covered Warren fuselage”, if you dug deep enough into the drawing system for the Harrier you will find parts that were used on Hunters, in fact there is a sringer section from Hurricane.

The design was right at the time, just the same as the Hunter, Harrier and Hawk designs where right at the time, I’ve worked with and in fact still do designers who started out on the Hunter then moved onto the Harrier and then Hawk, thus design methods and techniques do end up being used on the different aircraft.

I’ve also seen designs on the same aircraft that vary depending on where the designers where based, ie Warton, Brough and Kingston, all had there differnt construction methods, even in Germany parts of the Tyhoon designed by MBB in Munich differed to these designed in north germany.

Sean

Always interesting to hear a discussion on “What was the best aircraft of WWII”. Without exactly defining the scope it’s an unanswerable question.

I agree with JDK
“If by ‘Best’ we mean ‘fit for the purpose’ rather than ‘superior technology’, then the Hurricane’s construction was fine.”

The Hurricane was the right technology at the right time, other designs soon eclipsed it. The Hurricane continued to be used because it was then the right technology in the right place (i.e. Middle East etc.)

the Anson wouldn’t have anywhere near the same stresses on it in use as a fighter.

Good point, plus having a Fokker derived wooden wing…

I am given to understand that 4130 is the US equivilent of T50; obviously welding of tubing was possible in the 30’s and 40’s, but what grade of metal was used? the Anson wouldn’t have anywhere near the same stresses on it in use as a fighter.

As for which method is the best, try asking the question “Why was the Hawker Sea Fury (and everything that followed) designed as an aluminum semi monocoque?”

Ah, all those Sea Furies in the Battle of Britain, or those Spitfires available in 1939… 😉

If by ‘Best’ we mean ‘fit for the purpose’ rather than ‘superior technology’, then the Hurricane’s construction was fine – it was the last use of that technology, but the speed with which the Hurricane entered production, and was repaired in the pre-war RAF by Erks who ‘knew’ most of its technology, compared to the stressed skin construction Spitfire, Defiant, Battle and Blenheim indicates it was fit for the task. To have used the modular construction throughout the Typhoon would have been folly, to have switched Hawker’s factories to stressed skin construction Hurricanes would have lost the Battle of France perhaps quicker and certainly lost the Battle of Britain due to inadequate fighter numbers.

You are quite right, I’d agree with the Legacy element – but Hawker’s were also interested in having an effective production aircraft and took a safer bet than Boulton Paul and Supermarine…

The Spitfire was one of the greatest aircraft designs in history, indeed one of the iconic machines, but like Leonardo’s brilliant but popularly-overblown status, one can only interpret some responses in this forum on a semi-religious basis that the Spitfire was a Godlike machine, perfect in all aspects, and to notice any other is akin to the worship of false idols. Those in the Church of Spitfire are often quick to cast stones upon the followers of other temples (or those who are as interested in what happened and not pumping myth…) 😉

I’m pretty sure British Hurricanes were made of S80 steel (Spec now obsolete) and Canadian Hurricanes were 4130 steel.

As for why…… Last project legacy. If what is a left over from the last project is a factory with say 100 milling machines together with there skilled operators and 10 skilled welders then it pretty obvious my next aircraft will be a bolted construction design. We still see the same thing in the industry today… By way of an example the Boeing 777 Landing Gears major components are still welded assemblies (4340). This is because in the 1950’s the technology was developed and major investment occurred to install the expensive infer-structure which is still around today. The more or less rival A340 Landing Gear (300M) is machined from a larger forging with no welding.

Welded fuse frames were around at this time eg Anson so the weldable steel tube technology was around at this time. Anyone know how the operators got on with supporting that?

As for which method is the best, try asking the question “Why was the Hawker Sea Fury (and everything that followed) designed as an aluminum semi monocoque?”

I really cannot agree Mark V, in both cases the least you would have is a small entry and a exit hole. No big issue in either type.

Its a lot easier to patch a small hole in fabric than a stressed aluminium skin.

Elementary, my dear QLD

The welding of Chromeolly is doable.Firstly the item must be heated before and after welding to neautralise the stresses involved.How do I know??Using a two foot long heating torch to preheat fabricated beams in the engineering industry.All the more pleasant by doing it in a welding jacket in the middle of an Aussie summer.Then welding it with flux cored Mig wire then reheating.And all you used to guage the temp were welding crayons that turned colour when the correct temp was reached.:)
To keep the planes in the air the ground crew would have to accomplish all sorts of miracles with whatever was available.Bully beef tins,fence wire,bits of trees…..;)

Just a bit of clarification r.e the metal used in Spitfire engine bearers, it isn’t as previously suggested (by me ) 531, it is T50, which I am also informed cannot be welded, however its modern equivilant , T45 can be welded; whilst the steel tubing used in the construction of the Hurricane has to be something like that of T50 (as it is doing the same job), I don’t know its exact spec, so I cannot say conclusively that it cannot be welded ,however when you look at the other lightweight high tensile steel tubing, only the modern variant seem weldable.

Problem with semi Monocoques

Is that if you put a hole through a skin,hit a longeron or stringer that is primary damage.The problem is the secondary damage.Frames get distorted slightly,rivets may spring due to the skin flexing,brackets breaking etc.Sometimes the best way to fix it is to throw it in a fuse jig and go over the plane with a fine tooth comb.
IIRC the Hurri had a lot more access panels that would allow the erks to get to the job quickly,whereas with a Spit you either have to pullout the seat (a pain),pullout the radio equipment or climb in through the accumulator hatch at the tail end.
We frequently complain about building Spit bits due to the high number of “small” parts that constitute a sub assembly.Makes it worse by having a mate who helps us being familiar with P40 construction.Now that is a dream to build he says…:diablo:

I have done a bit more reading and the 1938(?) Flight reprint in “Hawker Hurricane Portfolio” by R.M Clarke indicates that the bolted fuselage structure was chosen solely because it was a known method of construction to Hawkers.

…Which had the advantage that it could be tooled up for very quickly with high spares availability. Before WW1 Sopwith pioneered the idea of having common ‘connectors’ with all aircraft made by that company and Hawkers carried this on. It meant that all the separate components could be built by ‘piece work’ and once someone had been trained to make a component you would have as many as you ever needed. I think they also used common tube diameters etc., common fork ends, wires and so on. The industry was prepared to build by these methods and the RAF was prepared to repair aircraft made like this.

It’s probably not true that the structure was easier to repair when it had suffered damage (Though I have read that the servicability of the Hurricane was better than the Spitfire(?). If so, this supports the easier to repair point of view.)

Fascinatingly complicated way to build an aeroplane

I still suspect it would be easier to deal with bolts and tubes than stressed skin. Ask someone who has operated a Pitts and switched to an Extra which was easier to fix! If it was a case of patching holes in the skin that’s one thing but what happenes if a stringer or a longeron is damaged?

Though as mentioned above, the fact that the Hurricane could be repaired and got back into service faster than the Spitfire in the Battle of Britain probably had as much to do with the fact that the RAF had had 20 years experience with that construction method compared to two years with stressed skin all metal.

f view.)

Fascinatingly complicated way to build an aeroplane

IIRC the Fiat Cr42 is much, much more complicated. Can anyone confirm or refute that?

Adrian

Typically British though. Over engineer it and then complain about how expensive it is. Why don’t buyers just admit that quality costs money? In the army we were always told to have faith in our equipment, our reply was “But be sure you know how to fix it as it was provided by the lowest bidder. Everyone seems to go for the cheapest solution rather than the slightly more expensive one which is actually up to the standard required for the job.

I have done a bit more reading and the 1938(?) Flight reprint in “Hawker Hurricane Portfolio” by R.M Clarke indicates that the bolted fuselage structure was chosen solely because it was a known method of construction to Hawkers.

It’s probably not true that the structure was easier to repair when it had suffered damage (Though I have read that the servicability of the Hurricane was better than the Spitfire(?). If so, this supports the easier to repair point of view.)

Fascinatingly complicated way to build an aeroplane

Holes…

It would usually be a small hole on one side and a bigger hole on the exit side.A machine gun round take a bit of material with it on the way through and punch it out the other side.The main diff is with cannon shells.In a Spit the shell would strike the skin,partially penetrate and explode,leaving the other side look like a colander or tear it apart like a tin can.In a Hurri with fabric the surface would tear allowing the round to go right through the plane without exploding.Thats unless it hit something substantial on the way through..

Precisely put – if you stand six feet from a Hurricane fuselage and shoot it with a revolver you may well not hit anything of structural consequence. If you did the same with a Spitfire the opposite is true!

I really cannot agree Mark V, in both cases the least you would have is a small entry and a exit hole. No big issue in either type.

Ahhh can see it now….

A dreary morning in England…June 1940….
“JENKINS!!!!!!”…
-“Yes sah!!!!”…
-“Where the Bleedin hell is my good Dinner Jacket!!!??”
-“It was hanging up to air this morning sah!!”
-“Well it,s not there now is it!!!”
-“Errr no sah,will kip around and see if anyone has seen it….”
-“Oh and one more think Jenkins….When did the order come down from Hq to paint the Hurricanes in new Cammo?”
-“Sah?????”
-“Yes that Hurri over there,G for George.The one with the black and white dots all over it……”
-“Errr dunno sah,she was up for an early morning hop.Will talk to the ground crew about it…”
-“Good lad and be quick about it….I have a dinner reservation with the Wingies family…”
😮

Point taken but don’t forget that a considerable proportion of the Hurricane’s fuselage was fabric covered, so there was quite a lot of thin air between the structural members. You wouldn’t even need a scab repair if it missed anything important. I guess it’s a trade-off between less miportant parts in the way, but more damage if one gets hit.

Precisely put – if you stand six feet from a Hurricane fuselage and shoot it with a revolver you may well not hit anything of structural consequence. If you did the same with a Spitfire the opposite is true!

I disagree with the view that the Hurricanes tubular construction was easier to repair in the field. I accept that it may have been more rugged and able to withstand rough treatment better than a aluminium stressed skin structure, and It also allowed better internal access for repairs, but it did concentrate its structural load paths in those critical tubes.
On the other hand the stressed skin structure carries the loads in a very different way, ie through the skin, stringers and longerons.

Point taken but don’t forget that a considerabe proportion of the Hurricane’s fuselage was fabric covered, so there was quite a lot of thin air between the structural members. You wouldn’t even need a scab repair if it missed anything important. I guess it’s a trade-off between less miportant parts in the way, but more damage if one gets hit.

Plus, of course, the Hurricane grew out of a monoplane derivative of the Fury (the pre-war one!), so we are talking logical development from late-1920s technology. This was an aeroplane designed to be patched up (literally, in the case of the fabric covered bits) by people who had years of experience of repairing aeroplanes thus constructed. When the devlopment began with the Hornet in 1929 or thereabouts, stressed skin technology would have been off-the-wall stuff.

Just my penn’orth.

Adrian

I disagree with the view that the Hurricanes tubular construction was easier to repair in the field. I accept that it may have been more rugged and able to withstand rough treatment better than a aluminium stressed skin structure, and It also allowed better internal access for repairs, but it did concentrate its structural load paths in those critical tubes.
On the other hand the stressed skin structure carries the loads in a very different way, ie through the skin, stringers and longerons. Punch a big hole in it and it stays together. Many examples of B17 damage show this. also field type repairs will consist of pop riveted patches or for bigger repairs solid riveted insert repairs, all simple stuff with tin snips, pop pliers, a drill and a hammer. Repair patches can be cut from another airframe in time of need in the same way.
A good example is “FLACK BAIT” the B26 in the Air and Space museum, thats covered in repaired holes all just pop rivetted scab patches.
I think the Hurricane fuselage construction method was just a progression from the Hart/Fury style and was on its way out with the Typhoon/Tempest and gone by the time the Sea Fury came along.

To keep the planes in the air the ground crew would have to accomplish all sorts of miracles with whatever was available.Bully beef tins,fence wire,bits of trees…..;)

Or in the case of the Hurricane, the next (unairworthy) Hurricane and a small toolbox.