Metal Mosquito built massively in the US

[swampyankee]

In general, before aircraft enter service predicting whether they'll be successful or not is never easy. In the case of the Mosquito, one must remember that the Mosquito was not built in response to an official RFP from the Air Ministry; it was built as a speculative venture by DeHavilland (De Havilland Mosquito | BAE Systems | International) after the company was ordered to shut up and build wings as a sub-contractor.

DeHavilland was probably uniquely capable of building a high-performance wooden aircraft, primarily as it had experience with the DH.88 Comet and (less successfully, given that one of the seven built crashed, with no deaths, due to "the wing starting to break up" [De Havilland DH.91 Albatross Transport], causing the DH91 to be withdrawn from service). I think secondary reasons may have been that the Air Ministry was open to such private ventures because of their desperation.

 

[Elmas]

In general, before aircraft enter service predicting whether they'll be successful or not is never easy. In the case of the Mosquito, one must remember that the Mosquito was not built in response to an official RFP from the Air Ministry; it was built as a speculative venture by DeHavilland (De Havilland Mosquito | BAE Systems | International) after the company was ordered to shut up and build wings as a sub-contractor.

DeHavilland was probably uniquely capable of building a high-performance wooden aircraft, primarily as it had experience with the DH.88 Comet and (less successfully, given that one of the seven built crashed, with no deaths, due to "the wing starting to break up" [De Havilland DH.91 Albatross Transport], causing the DH91 to be withdrawn from service). I think secondary reasons may have been that the Air Ministry was open to such private ventures because of their desperation.

And I'm certain that there was also a certain amount of lobbying activity. Management of de Havilland factory had certainly some "hooks" in the Air Ministry and perfeclty knew that a stop in the production of airplanes of their own design would have been disastrous for their post-war bussines.

 

[Conslaw]

To elaborate on a theme raised in Shortround6's posts: a metal plane with specifications very close to the Mosquito was well into the planning stage in the US in 1940. To quote from Joe Baugher's website on the XA-26:

The A-26 Invader originally began as a private venture on the part of the Douglas plant at El Segundo, California. In the autumn of 1940, Douglas began a preliminary design study to develop a common successor to the Douglas A-20, Martin B-26, and North American B-25 bombers, none of which had yet entered service with the US Army Air Corps. The Bomber Branch of the Experimental Engineering Section at Wright Field, Ohio assisted in this effort by pointing out some of the deficiencies of the company's DB-7 twin-engined attack bomber that they had evaluated--lack of crew interchangeability, insufficient defensive armament, inadequate offensive firepower, and excessively long landing and takeoff distances.

At the end of January 1941, a team led by Edward Heinemann and Robert Donovan had come up with a proposal for a new twin-engined attack aircraft that would satisfy these requirements. It had a broad general family resemblance to the A-20 Havoc which was just then entering service with the Army Air Forces. It featured a mid-mounted wing with a laminar flow aerofoil and which was fitted with electrically operated double-slotted flaps. The aircraft was to be powered by a pair of 2000-hp Pratt & Whitney R-2800-77 air-cooled radials. The aircraft was to have a large internal bomb bay capable of carrying 4000 pounds of bombs or two torpedoes, and was to be fitted with external racks underneath the outer wings for additional ordnance. The defensive armament was to be provided by a pair of remotely-controlled dorsal and ventral turrets, each housing two 0.50-inch machine guns and operated by a gunner sitting in a separate compartment behind the bomb bay.

A decision was made that the aircraft would be built in two separate versions, a three-seat light bomber version with a transparent nose for a navigator/bombardier and a two-seat night-fighter version with a solid nose carrying heavy forward-firing armament and AI radar. The two versions were to be essentially identical except for their noses.

The mockup was inspected between April 11 and 22 of 1941, and on June 2 the War Department authorized the construction of two prototypes under the new designation A-26. The first aircraft was to be a three-seat attack bomber version with a transparent nose and was to be designated XA-26-DE. The second aircraft was to be a two-seat night fighter version designated XA-26A-DE. Three weeks later, the contract was amended to include a third prototype designated XA-26B-DE. It was to be a three seat ground attack aircraft with an unglazed nose housing a 75-mm cannon.

So, well before the US entered the war, the groundwork was laid for the A-26, and if the A-26 had the same priority and same focus on getting into service quickly and in quantity as the B-29, then large quantities of A-26 bombers could have been in service in 1943. The development of the A-26 became bogged down for a lot of reasons, with probably the biggest reason was that Douglas had a lot of projects going on at the same time. The A-26, when it did become combat capable, was not as fast as the Mosquito, but it theoretically could have been if that had been the priority.

 

[nuuumannn]

it had some "industrial" bottlenecks not easy to overcome to increase the production to huge numbers in short times.

So, where were these bottlenecks on what form did they take? Books I have on the type mention no 'industrial bottlenecks' concerning its production, so where did you find this claim?

According to Sharp and Bowyer in their book Mosquito (Crecy, 1995), de Havilland made outlandish promises in July 1940 while the prototype was under construction, of 50 Mosquitoes by December 1941, but the Air Ministry told Hatfield not to escalate tooling too much as the firm might not be able to deliver on its promise. The area that really facilitated production of the type was the fact that major components were sub-contracted and this saved expectations at Hatfield in terms of tooling and staffing for the future. The book also mentions the fact that sub-contracting actually sped production to meet demand and all evidence in the book shows that things happened smoothly as a result of the decision to sub-contract, with companies willing to facilitate this, which meant that the flow of airframes began to meet demand as it was at the time. One area identified as problematic was the Air Ministry's demands for both fighter and bomber types, not being entirely clear of the numbers it wanted of each to begin with.

The following from the book indicates the RAF's receipt of the type :

"After taking their fiftieth aircraft in mid-March 1942, the RAF had fifty more in the next two months, the 101st by 30 May. They had the 408th by 28th November (Hatfield 366, Leavesden 42), and the 1,000th in June 1943 (Hatfield 775, Leavesden 198 by 21 June). Thus the production rate was one a week in late 1941, three a week in early 1942, eight a week by midsummer, 12 to 14 a week by the end of 1942 and double that a year later from all sources."

I'm also well aware that the Lancaster is a larger and more complex aircraft to build than the Mosquito, but the point is that within a similar time period, the Mosquito's production figures are comparable to other types built by Britain during the war.

 

[Conslaw]

So, where were these bottlenecks on what form did they take? Books I have on the type mention no 'industrial bottlenecks' concerning its production, so where did you find this claim?

According to Sharp and Bowyer in their book Mosquito (Crecy, 1995), de Havilland made outlandish promises in July 1940 while the prototype was under construction, of 50 Mosquitoes by December 1941, but the Air Ministry told Hatfield not to escalate tooling too much as the firm might not be able to deliver on its promise. The area that really facilitated production of the type was the fact that major components were sub-contracted and this saved expectations at Hatfield in terms of tooling and staffing for the future. The book also mentions the fact that sub-contracting actually sped production to meet demand and all evidence in the book shows that things happened smoothly as a result of the decision to sub-contract, with companies willing to facilitate this, which meant that the flow of airframes began to meet demand as it was at the time. One area identified as problematic was the Air Ministry's demands for both fighter and bomber types, not being entirely clear of the numbers it wanted of each to begin with.

The following from the book indicates the RAF's receipt of the type :

"After taking their fiftieth aircraft in mid-March 1942, the RAF had fifty more in the next two months, the 101st by 30 May. They had the 408th by 28th November (Hatfield 366, Leavesden 42), and the 1,000th in June 1943 (Hatfield 775, Leavesden 198 by 21 June). Thus the production rate was one a week in late 1941, three a week in early 1942, eight a week by midsummer, 12 to 14 a week by the end of 1942 and double that a year later from all sources."

I'm also well aware that the Lancaster is a larger and more complex aircraft to build than the Mosquito, but the point is that within a similar time period, the Mosquito's production figures are comparable to other types built by Britain during the war.

The production delays for the A-26 included the Army's indecision of which variant to produce in what quantities and where. Douglas's Santa Monica plant was already building the A-20, C-47 and C-54. The A-26 was ultimately built in newer plants in Tulsa and Long Beach. As to variants: The "A" was a nightfighter - which did not enter serial production. The "B" was solid-nose, with the AAF undecided on whether to prioritize the 75mm cannon version or machine guns. The "C" model had the glass nose for a bomb-aimer.

The Fifth Air Force received a few service-test examples and put them into combat in June 1944. The pilots hated these early planes, with the biggest complaint that the pilots couldn't see the ground over the engines. General Kenney wrote "We do not want the A-26 under any circumstances as a replacement for anything. " Douglas then had to do an emergency redesign to change the field of vision, and the redesign was apparently effective.

 

[Elmas]

So, where were these bottlenecks on what form did they take? Books I have on the type mention no 'industrial bottlenecks' concerning its production, so where did you find this claim?

According to Sharp and Bowyer in their book Mosquito (Crecy, 1995), de Havilland made outlandish promises in July 1940 while the prototype was under construction, of 50 Mosquitoes by December 1941, but the Air Ministry told Hatfield not to escalate tooling too much as the firm might not be able to deliver on its promise. The area that really facilitated production of the type was the fact that major components were sub-contracted and this saved expectations at Hatfield in terms of tooling and staffing for the future. The book also mentions the fact that sub-contracting actually sped production to meet demand and all evidence in the book shows that things happened smoothly as a result of the decision to sub-contract, with companies willing to facilitate this, which meant that the flow of airframes began to meet demand as it was at the time. One area identified as problematic was the Air Ministry's demands for both fighter and bomber types, not being entirely clear of the numbers it wanted of each to begin with.

The following from the book indicates the RAF's receipt of the type :

"After taking their fiftieth aircraft in mid-March 1942, the RAF had fifty more in the next two months, the 101st by 30 May. They had the 408th by 28th November (Hatfield 366, Leavesden 42), and the 1,000th in June 1943 (Hatfield 775, Leavesden 198 by 21 June). Thus the production rate was one a week in late 1941, three a week in early 1942, eight a week by midsummer, 12 to 14 a week by the end of 1942 and double that a year later from all sources."

I'm also well aware that the Lancaster is a larger and more complex aircraft to build than the Mosquito, but the point is that within a similar time period, the Mosquito's production figures are comparable to other types built by Britain during the war.

There are many reasons of course involved, each affecting others.
First of all, manpower specialised in wood construction. While it is relatively simple to instruct a riveteer, it is not so easy to form a cabinet maker.

In the period of the industrialization of Italy (early 50s mid 60s), tens of thousands of agricultural workers went from the deep south of Italy to the north to work at the Piaggio or Fiat factory and it was very straightforward to train and put them in front of a press, or in front of an automatic drilling machine. The same thing can't be said for woodworking: if you put a not perfectly trained and experienced person in front of a table saw, it is most probably he will not only cut the plank, but also one of his hands.

Wood it is not aluminium: it bends, it cracks, it warps, it spilts and an experienced woodworker at first glance "sees" how to cut a plank in order to minimize those defects. Certainly, the use of half-processed material like plywood can help, but up to a point.

When I was younger I was involved in sailing racing and I was a friend of an old marine carpenter.
One day I helped him to replace a rotten board in an old traditionally built boat.
After spending half an hour looking for the right board from a big pile, he showed it to me and said: "You see, Sir, we will put this board and it will surely sag. But if we put it like this it will tend to tighten the joints and the water will not go in. If instead we put it to the contrary, the board will tend to widen the joints and the boat will leak."
How many years did that carpenter take to figure out which plank to use, and how to set it up on the boat?

Another small example.

To glue a wooden joint perfectly it must be subjected to strong pressure, and to exert a strong pressure either very powerful presses or many clamps are required.
If this pressure is not exerted perfectly in all probability the joint will tend to unglue, with a result not exactly edifying in an airplane.

Anyone who goes to a traditional woodworking shop is amazed by the dozens, if not hundreds, of metal clamps hanging on the walls: so, before building a wooden airplane, you must have the presses and clamps available, and if you don't, you have to produce presses and clamps.
de Havilland had already some problems about this matter

De Havilland DH.91 Albatross Transport

There are many other reasons... I love woodworking, and I'm involved with it both professionaly and as a hobby.

 

[NevadaK]

NIce question.

I guess from my perspective the question isn't could you build as mosquito from aluminum, which it seems that you could, but could it be built better in North America. Plywood and laminated wood assemblies were quite advanced in the US and Canada and a number of technologies associated with them were being pushed by the war effort. Preforming plywood assemblies and structural laminating in particular advanced rapidly and I suspect that a Mosquito manufactured in the US would benefit from the incorporation of some of these technologies. Mixed material assemblies (wood aluminum) were not as far along in the US, but one could imagine that this technology would develop faster if there was a need such as a significant emphasis on uses in aviation.

I'm aware that the Curtis C-76 Caravan debacle counters this argument, however, there were a number of poor choices associated with that project, such as mahogany core vs balsa core plywood and use of a bad manufacturer.

Sticking with wood has a number of advantages. You aren't competing for materials and manpower with other major aviation projects. The aircraft would be sooner to production as you climate the time required to reverse engineer and test a new airframe. There is significantly more latent capacity in the laminated wood industry than aluminum which can be ramped up more quickly. More Mosquitos sooner.

Just my thoughts.

Kk

 

[Conslaw]

NIce question.

I guess from my perspective the question isn't could you build as mosquito from aluminum, which it seems that you could, but could it be built better in North America. Plywood and laminated wood assemblies were quite advanced in the US and Canada and a number of technologies associated with them were being pushed by the war effort. Preforming plywood assemblies and structural laminating in particular advanced rapidly and I suspect that a Mosquito manufactured in the US would benefit from the incorporation of some of these technologies. Mixed material assemblies (wood aluminum) were not as far along in the US, but one could imagine that this technology would develop faster if there was a need such as a significant emphasis on uses in aviation.

I'm aware that the Curtis C-76 Caravan debacle counters this argument, however, there were a number of poor choices associated with that project, such as mahogany core vs balsa core plywood and use of a bad manufacturer.

Sticking with wood has a number of advantages. You aren't competing for materials and manpower with other major aviation projects. The aircraft would be sooner to production as you climate the time required to reverse engineer and test a new airframe. There is significantly more latent capacity in the laminated wood industry than aluminum which can be ramped up more quickly. More Mosquitos sooner.

Just my thoughts.

Kk

I'm wondering if the skilled labor to build a wooden aircraft was in more short supply in the United States than aluminum. The US found enough aluminum to make 200,000 aircraft after all, with a good number of them being large for the time. The Mosquito was built in Canada., over a thousand.

 

[Elmas]

Certainly in U.S. there were the resources to build wooden Mosquito but I think also that the American Aviation Industry would not have been too happy.
"We will build a better airplane our own way..." would have been the reply to the request, I think...
And even if Mosquito was one of the safest planes of the war, neither would have been USAAF Generals, I think, risking in numbers their very precious crews in missions on the Mosquito other than PR.
We are in the "what if" section, of course...

 

[swampyankee]

There were (and are) fine makers of wooden furniture in the US; during WW2, there was also production of wooden boats, pianos, and wooden musical instruments. There are still a companies producing wooden aircraft propellers and wooden boats.

That said, the makers of large US aircraft had stopped manufacture of primary structure from wood, and would need time to relearn or learn those skills. For the relatively small number of Mosquitoes which were foreseen, the decision was made that this wasn't a worthwhile effort to get involved in: Mosquitoes would be obtained via reverse Lend-Lease, along with Spitfires and some other British aircraft. An aluminum Mosquito would be a completely new aircraft even if it looked like a Mosquito from a distance, it would take at least two years from project initiation to production. I also suspect that the Aluminum Mosquito would suffer badly from NIH syndrome, and the USAAF would insist upon massive changes to better fit their perceived needs.

 

[Deleted member 68059]

Just for general interest:

The Plane That Saved Britain: The Plane That Saved Britain - On Demand

At about the 10minuite mark, one of the orginal design team who did much of the performance projection mathematics, David Newman, said the rivet heads of an all-metal construction would have
cost them 20mph.

Cant speak for the absolute accuracy of that remark, but I also have no particular reason to disbelieve it either.

 

[tomo pauk]

Just for general interest:

The Plane That Saved Britain: The Plane That Saved Britain - On Demand

At about the 10minuite mark, one of the orginal design team David Newman said the rivet heads of an all-metal construction would have
cost them 20mph.

Cant speak for the absolute accuracy of that remark, but I also have no particular reason to disbelieve it either.

Thank you for the heads-up.

On a different note - just imagine if they were doing the riveting on the Mosquito (for any reason). It would've certainly failed to save Britain.

 

[Conslaw]

Just for general interest:

The Plane That Saved Britain: The Plane That Saved Britain - On Demand

At about the 10minuite mark, one of the orginal design team David Newman said the rivet heads of an all-metal construction would have
cost them 20mph.

Cant speak for the absolute accuracy of that remark, but I also have no particular reason to disbelieve it either.

IIRC, Corky Meyer said in his book that one reason the F4U was significantly more expensive than the F6F was the F4U used flushed rivets throughout, and the af6F only used them where it really mattered. I don't own the book, I got it from the library, so I can't provide a quote. Of course, the F6F was 10-20 mph slower than contemporary F4Us, but there were a variety of factors at play, and not just rivets.

 

[NevadaK]

There were (and are) fine makers of wooden furniture in the US; during WW2, there was also production of wooden boats, pianos, and wooden musical instruments. There are still a companies producing wooden aircraft propellers and wooden boats.

That said, the makers of large US aircraft had stopped manufacture of primary structure from wood, and would need time to relearn or learn those skills. For the relatively small number of Mosquitoes which were foreseen, the decision was made that this wasn't a worthwhile effort to get involved in: Mosquitoes would be obtained via reverse Lend-Lease, along with Spitfires and some other British aircraft. An aluminum Mosquito would be a completely new aircraft even if it looked like a Mosquito from a distance, it would take at least two years from project initiation to production. I also suspect that the Aluminum Mosquito would suffer badly from NIH syndrome, and the USAAF would insist upon massive changes to better fit their perceived needs.

Looking at the weights of comparable aircraft, I'm not sure that there would be any weight savings associated with an aluminum version of the Mosquito.

I agree that there would be a strong tendency on the part of US manufacturers and military to "refine" the design to better suit perceived roles and design ideas. To me, I think it would be likely that there was a desire to switch engines to a radial along the lines of an R2800 as was more normal for US Bomber/Attack aircraft.

 

[Elmas]

Spitfire test pilot Jeffrey Quill recounts how they prototyped a 'pop rivet' Spitfire by sticking a split pea onto the the many thousands of flush-headed rivets that covered the plane. They then test flew the plane, that was remarkably slower... some 22 mph , if I remember well.

 

[pbehn]

Spitfire test pilot Jeffrey Quill recounts how they prototyped a 'pop rivet' Spitfire by sticking a split pea onto the the many thousands of flush-headed rivets that covered the plane. They then test flew the plane, that was remarkably slower... some 22 mph , if I remember well.

Wasn't that an experiment to find which could be left as pop rivets without seriously harming performance?

 

[Elmas]

Wasn't that an experiment to find which could be left as pop rivets without seriously harming performance?

Exactly. So they were able to progressively scrape off lines of peas, retest, and identify the critical areas. Many unnecessary lines of flush riveting were eliminated.

 

[NevadaK]

Exactly. So they were able to progressively scrape off lines of peas, retest, and identify the critical areas. Many unnecessary lines of flush riveting were eliminated.

In a similar vein, I don't know how many of you ever watched Mythbusters, but one of the episodes included covering a car with golf ball style dimples which made a noticeable improvement in the aerodynamics of the car. To do this, they covered it in clay and then impressed the dimples. While the car got heavier due to the clay it also got slipperier and improved gas mileage.

 

[NevadaK]

The first ten minutes or so are about the Mosquito. Nice flying sequences.

84474 US News Review A Plywood Bomber_vwr.mov

 

[ThomasP]

Aluminum is ~3x stronger than wood, but is also ~3x heavier than wood. There is a general rule in engineering of omnidirectional stressed structures (ie assemblies that have to deal with forces from different directions, sometimes from all directions at once) that although aluminum is ~3x stronger, if you thin an aluminum structural member to 1/3 the weight (ie the walls of the I-beam, channel-beam, Z-stringer, etc), it will only be about 50% as rigid/non-deformable as the same weight wooden structure. Note that this is a rule that assumes the use of appropriate materials, or about the best type of materials (ie ply-balsa-ply sandwich vs high quality aluminum), best structural member shapes (I-beam/channel/z-stringer/box girder/etc), glues/welds, etc, in an appropriate overall structure (monocoque and stressed skin in this case). What this works out to in a practical sense is that an aluminum Mosquito airframe (of the same shape/volume/intact strength/etc) would weigh about 40% (if I did my math right) more than the wood one.

This is part of the reason that the Mosquito could carry the same ~payload as the B-25/B-26 but weigh about 2/3 as much. And this is part of the reason that De Havilland continued using wood composite construction for some of the company's early jet aircraft. When used in the appropriate areas of the airframe it saved significant weight - a particularly important factor in the early under-powered jets of the time.

EDIT: When I say airframe in this instance I am only referring to the wooden strength bearing and aerodynamic form structures, etc, plus any metal structure re-enforcements - not the landing gear, engine mounts/bearers, fuel tanks, wiring, etc.