What if Mosquitoes were made out of metal?

[fastterry]

I was following a build log of a Tamiya 1/32 Mosquito when a member posted a photo of the bomb bay saying it could fit a 4000lb 'cookie' (Mk XVI) and made a reference to the N.A. B-25 only carrying 2000lb more with an extra 3 crew. I understand why the Mosquito was made of wood, less drain on resources and de Havilland's extensive experience building wooden aircraft. My thought was let the Americans build them in metal and supply them under lend/lease. The design of the size and shape was done and the engines could be Packard Merlins (used on Canadian Mosquitoes anyway). The major task would be stressing the airframe to be built in metal, plenty of troops on the other side of the pond for that. North American could make them instead of B-25's. Advantages are much higher max. and cruising speeds, smaller airframe (13' shorter in wingspan and length) lighter weight than wood (potentially higher speeds) and less crew needed. Airframes would last longer in tropical climes and there might be a few more around as warbirds. Now I know that the Americans would rather have handed Alaska over to the Japanese than make an English aircraft. Just thinking while the paint dries.

Serious comments only please🙃

TRF

[Scimitar F1]

Wood has a higher specific strength (strength for a given weight) than aluminium and was only bettered with carbon fibre. So a metal Mosquito would not be faster

it has disadvantages however, some that you mention and requires a different design philosophy. DH made it work as they had experience with it. 

[Jamie @ Sovereign Hobbies]

Design of the size and shape can be done in a few days with simple calculations which a relative amateur can do nowadays. Some of the aerodynamic refinements are worth a bit more effort, but the fact remains that over 90% of the design effort is designing where to put material, how thick the material needs to be to carry the stresses and how to attach the components together. To prepare for manufacture Mosquitos needed fuselage moulds and various jigs. Metal aircraft need lots of jigs plus lots of forms and stamps for all the components. The Mosquito's monocoque fuselage would have been an absolute bear to build from metal in relation to American mass production preferences, so in reality the Mosquito's shape would have gone out the window too to make something that could be made easily from simpler shaped bits of sheet metal (i.e. minimising stretched/formed double curvatures).

 

A metal Mosquito would have defacto been a completely new aircraft sharing nothing but its choice of engines and general philosophy of trading defensive armament for speed.

[fastterry]

The build article got me started but it also reminded me of the Ki.106 (the wooded version of the Ki.84 Hayate) which was 600lb (275kg) heavier than the metal Ki.84. The other thing with the design, is the whole concept is there, high speed, un-armed bomber that doesn't need escort and is proven in combat. The metal version would have been built after de Havilland had built production machines and they had been used on ops. I agree the fuselage shape would have been a problem and that some of the cleanliness of the lines compromised but the wings wouldn't have been a problem with nice straight leading edges. Just to stir the pot some more why were 85% of aircraft manufactured during WW2 built of metal considering as a combat weapon, they were expendable. All this is what if so no need to get too serious about it.

Love your paints Jamie, by the way.

TRF

[Bandsaw Steve]

More importantly - why aren’t more kitsets made out of wood! 😠

[Duncan B]

6 minutes ago, Bandsaw Steve said:

More importantly - why aren’t more kit sets made out of wood! 😠

Converting the moulds from high pressure injection plastic to high pressure injection wood adds complexity and weight to the design much like in the real world trying to convert a design intended for one type of material manufacture process into another.

 

Duncan B

[Duncan B]

To answer the OP, if you made a Mosquito out of metal you would have a Me410

 

Duncan B

[Bandsaw Steve]

‘High pressure injection wood’...oh errr...😱

 

Mods - I think we need your guidance here.

 

 

[Giorgio N]

Replacing the B-25 production lines with a metal variant of the Mosquito would assume first of all that the Mosquito could have been able to replace the B-25 and this means that the operating principles of the Mosquito would have had to be adopted by all forces using the B-25. Something that may have been even more difficult than convincing NAA or another US manufacturer to go through the trouble of redesigning such metal variant.

Then there's also a financial matter: Lend-Lease aircraft were US built but the agreement did not include development costs. Such costs would have had to be covered by either NAA or the British. Would any of the two have risked the money ? Most likely NAA would have just been happy producing an aircraft that they already had in house,

Of course as others have said the final result would have been something following the Mosquito philosophy but likely quite different from the Mosquito in shape.

 

As to why metal was used in most aircraft, there are many good technical reason and then another very important one: metal structures are much better suited to mass production.

It should also be said that for most participants in the war the feared lack of aluminum did not materialise except in a few cases (like very late WW2 Germany). There were many projects of types built using "non strategic" resources during the war but in the end most never really made into production for this reason. The Mosquito is one very happy exception, but still an exception

[Graham Boak]

Well, for exceptions you could have mentioned the almost entire range of  Russian fighters,  largely made from resin-impregnated birch "Schpon".  However the Russians substituted aluminium for the wing spars as more of this became available them.  As did everyone else.

 

Wood is not necessarily lighter strength for strength than metal, but it is inevitably thicker and less predictable (which means make it even thicker and heavier for safety).  This creates other problems on internal volume and aerodynamic wing thickness - it might have been possible to produce a (heavier) Hurricane wing out of wood but not a Spitfire.  Given the multiple laminated structure of the Mosquito, I'm not so sure that production was all that much easier than conventional metal structures.  It did however allow the use of qualified workmen trained in wood rather than metal - though given the expansion of production I wonder just what proportion of the workforce was unskilled anyway.

 

Only a few Mosquitos carried the 4000lb, and these were heavily restricted on handling.  Normal bomb load was half that.  I suspect that had the occasion demanded a bulged bombbay could have been fitted to the Mitchell to increase its payload.  

[JohnT]

One other matter that would have probably played a part in US thinking is their philosophy as regards bomber defensive armament. Apart from their use of the Mosquito as a photo recon aircraft  and the B-57 (where a lack of a gun was initially an issue for the USAF)  did they ever have a home grown bomber that had no defensive armament at all ?  Even the B-47, B-52 and B-58 had tail guns, the latter at Mach 2 dash too. 
Even medium bombers and light bombers were well kitted out with plenty 0.50 cals.   I always thought the Martin Marauder was a mini B-17. 
 

I just don’t see Uncle Sam sending their boys into harms way without having the means to shoot back - the PR speciality excepted. 

[Paul821]

The OP's question in the title is !"What if Mosquitoes were made out of metal?" one answer is there probably would not have been as many. As the site of the RAAF museum says

 

"However, de Havilland had surmised that in time of war aluminium for aircraft would be a very scarce commodity, and so would the expertise of those personnel who were skilled in the metal construction. There would be, on the other hand, many experienced carpenters, piano, cabinet, and furniture makers available whose skills could be used."

 

https://www.airforce.gov.au/sites/default/files/minisite/static/7522/RAAFmuseum/exhibitions/restoration/dh_98.htm

 

 

[Blimpyboy]

1 hour ago, JohnT said:

I just don’t see Uncle Sam sending their boys into harms way without having the means to shoot back - the PR speciality excepted.

They should have made the P-38 and A-20 out of wood, then.

They would (wood) have been world-beaters and wouldn’t (woodn’t?) need no stinkin’ guns... 😉

 

 

Edited August 31, 2020 by Blimpyboy

[Bandsaw Steve]

54 minutes ago, Paul821 said:

 

 

"However, de Havilland had surmised that in time of war aluminium for aircraft would be a very scarce commodity, and so would the expertise of those personnel who were skilled in the metal construction. There would be, on the other hand, many experienced carpenters, piano, cabinet, and furniture makers available whose skills could be used."

 

This is fantastic! Since I’m both a Mine Geologist and a woodworker, either way I would never have to go to war! 👍

[EwenS]

1 hour ago, Graham Boak said:

Well, for exceptions you could have mentioned the almost entire range of  Russian fighters,  largely made from resin-impregnated birch "Schpon".  However the Russians substituted aluminium for the wing spars as more of this became available them.  As did everyone else.

 

Wood is not necessarily lighter strength for strength than metal, but it is inevitably thicker and less predictable (which means make it even thicker and heavier for safety).  This creates other problems on internal volume and aerodynamic wing thickness - it might have been possible to produce a (heavier) Hurricane wing out of wood but not a Spitfire.  Given the multiple laminated structure of the Mosquito, I'm not so sure that production was all that much easier than conventional metal structures.  It did however allow the use of qualified workmen trained in wood rather than metal - though given the expansion of production I wonder just what proportion of the workforce was unskilled anyway.

 

Only a few Mosquitos carried the 4000lb, and these were heavily restricted on handling.  Normal bomb load was half that.  I suspect that had the occasion demanded a bulged bombbay could have been fitted to the Mitchell to increase its payload.  

 

A little context for Graham’s final comment from Sharp & Bowyer’s Mosquito.

 

First suggestions of fitting the 4,000lb Cookie in a Mosquito - cApril 1943. First conversion of a Mk.IV flew July 1943. 20 Mk.IV conversions and at least 1 Mk.IX before decision taken not to convert any more of those Marks due to the handling difficulties mentioned. First operational sortie to drop one was 23rd Feb 1944. It was intended from the outset that the B.XVI should carry the 4,000lb bomb, becoming operational in Feb 1944.

 

Amongst the stats in that book is data to the effect that the 11 Mossie squadrons in 8 Group took 1,459 4,000lb bombs to Berlin in Jan-Apr 1945 and a further 1,572 to other targets in Jan-May. That from 9,288 operational sorties in those months. So in the final months of the war nearly one third of Mosquito sorties were flown with Cookies.

 

Unfortunately there is no comparable bomb data for 1944, although we do know that 8 Group Mossies flew 16,117 sorties that year, starting with 4 squadrons and building up to 10 in Dec. The numbers of Cookie sorties would have built up from Feb but there was probably a much lesser percentage than compared with 1945.

 

 

[Graham Boak]

How does that total compare with that dropped by the heavies in how many sorties?  How more trained pilots and navigators (the most expensive crew) required per 1000 bombs?  

What about the light bombers in 2 TAF?   Would it be two or three Mosquito sorties per Mitchell?  ( Figures from the Normandy campaign showed that fighter-bombers were more efficient anyway.)

 

The Mosquito was a great PR machine and an equally great heavy fighter, but as a day bomber they were good for propaganda but its loss rate was greater than that of the Blenheim which preceded it.  (To be fair, they were flying some missions that the Blenheim could never have carried out.)

 

 

[Scimitar F1]

7 hours ago, Graham Boak said:

Wood is not necessarily lighter strength for strength than metal, but it is inevitably thicker and less predictable (which means make it even thicker and heavier for safety).

The greater volume is what makes it stronger for a given weight (Think broomstick compared to a comparable piece of steel for the same weight). It is not stronger for a given volume that you allude to with the Hurricane wing analogy. That is why it needs a different design philosophy. It is much closer to that with carbon fibre - also a heterogeneous material (stronger in one direction than another.

[Graham Boak]

When it comes to combat aircraft, increased volume. means increased drag.  This is not a good thing.  Switch your example around - what is the strength of a broomstick made from the same volume of steel - or rather aluminium?  Better make it a metal tube - what's the difference in weight then?  The world's aircraft designers were not fools, they were well aware of the strength of wooden structures having been designing them for years.  In all nations they found superior performance, greater strength and reduced weight from light metal structures.  Trying to make wooden examples to do the same job resulted in heavier structures.  Universally.  I remain convinced that an aircraft of the Mosquito's shape and size would have been superior in metal, if De havilland had chosen to do it that way and had an appropriately trained design staff and workforce.  That it may then have been more expensive in production cost might make an interesting discussion if we had directly comparable data - which we don't and obviously can't get.  We might get close if we had equivalent figures for the Mosquito, A-20, B-25 and A-26.  Or perhaps Beaufighter and Whirlwind, but for various reasons none of these are exact equivalents.

[Scimitar F1]

30 minutes ago, Graham Boak said:

When it comes to combat aircraft, increased volume. means increased drag

I am not talking overall volume of the airframe rather the volume of each structural member. Happy to chat offline where I can take you through my structures notes from my Aeronautical engineering degree. I also can talk materials from the enhanced materials component.

 

On the metal airframe aircraft being faster etc what we can say is that no one managed it in WW2 - Me 410 was probably the closest in design concept. If metal was that much better someone would have managed it - Messerschmidt were no slackers. When DH came to make the Hornet the structure was a hybrid of wood and metal with the wing spar being the latter. 

Edited August 31, 2020 by Scimitar F1

[Graham Boak]

Increasing the volume of the structural members means decreasing the internal volume of the aircraft hence reduced fuel and/or systems and/or payload.  In particular, thicker spars means thicker draggier wings.

 

My Aeronautical degree didn'r go into such details as wood vs metals, and structures wasn't a strong point anyway.  Perhaps more less practical and more aeronautically/academically biased.  Also too long ago.  I am however happy to rest on the recorded history of aviation when it comes to these matters.  We have to note what was done at the time with the knowledge of the time - high performance wooden aircraft could be built but it was not the structural material of choice.

 

Also, wooden aircraft require more maintenance and last less well - perhaps less important when it comes to the short life of WW2 combat types, except when wings start falling off.  Not that such things were unique to wooden aircraft, of course, but rot was.

[wellsprop]

It's not possible. 

 

The Mosquito is a composite, monocoque airframe. This is/was not possible with aluminium (which would require a semi-monocoque construction).

 

Wood, like carbon fibre, is an anisotrpic material (it does not have constant mechanical properties in each direction). This allows engineers to design the layup to have strength where needed (primary force/stress/direction) but it can be lightweight in the direction that is not a load path.

 

If it were made out of metal, it would have required a semi-monocoque design with ribs and stringers (for arguments same, let's say it would use a stressed skin, like the Spitfire, to again reduce load through the structural frames). It simply would not have been the same aircraft, even if it had an identical outward appearance.

[Max Headroom]

12 hours ago, Duncan B said:

To answer the OP, if you made a Mosquito out of metal you would have a Me410

 

Duncan B

Or a TA154!

 

Trevor

[Blimpyboy]

I agree - had DH intended the Mosquito to be metal from the outset, the resultant design would probably be totally unrecognisable to us today!

 

Wood is also problematic as a resource, more so than many may think. Mossies were made of many different types of wood, and of the forests of wood that were felled, DH reportedly rejected huge quantities due to requisite quality issues.

Additionally, metal (of specific types and shapes) has much better ‘known’ qualities in terms of long term strength and lifespan - for the insomniacs out there, here is a good piece in the qualities of wood as a structural material:

https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf

 

Edited August 31, 2020 by Blimpyboy

[wellsprop]

1 hour ago, Blimpyboy said:

I agree - had DH intended the Mosquito to be metal from the outset, the resultant design would probably be totally unrecognisable to us today!

 

Wood is also problematic as a resource, more so than many may think. Mossies were made of many different types of wood, and of the forests of wood that were felled, DH reportedly rejected huge quantities due to requisite quality issues.

Additionally, metal (of specific types and shapes) has much better ‘known’ qualities in terms of long term strength and lifespan - for the insomniacs out there, here is a good piece in the qualities of wood as a structural material:

https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf

 

I've not heard about the issues DH had with wood supply. I don't for one minute think it is untrue however, maintaining constant mechanical properties across large sections of wood must have been extremely difficult.

 

Thanks for that link to the mechanical properties too, that's rather interesting/useful (to me at least)  I could have done with that when I did deflection and bending moment calculations for my decking 😂

 

I think asking what the mosquito would have been like if it were made from metal is like asking what the Spitfire would have been like if it were made from wood and fabric I.e. an entirely different aircraft. 

 

I think the comparison with the Me 410 is broadly reasonable (though perhaps without the stability issues). Maybe it would have been like a mosquito, minus mosquitos unique and superb performance.

[Giorgio N]

21 hours ago, Graham Boak said:

Well, for exceptions you could have mentioned the almost entire range of  Russian fighters,  largely made from resin-impregnated birch "Schpon".  However the Russians substituted aluminium for the wing spars as more of this became available them.  As did everyone else.

 

 

Good point Graham, I made a typical "western" mistake of forgetting what was going on in the Soviet Union.