De Havilland Mosquito (Wood vs. Metal)

[Zipper730]

This isn't really meant to be a debate as to whether the Mosquito would be better off made of metal (it wouldn't, it'd tie up metal resources) more of a question as to how much a plane with the basic shape of the Mosquito would weigh if it was made of Aluminum alloy instead of wood for the overall ultimate load factor (8g), fuel and payload.

P pbehn S Shortround6 X XBe02Drvr

 

[SaparotRob]

Wouldn't that be the Hornet?

 

[pbehn]

Wouldn't that be the Hornet?

The Hornet wasnt a light bomber but was comparable to the Tigercat, apart from it was just a single seater to start with, and had lighter engines and the Hornet was land based, the sea Hornet was carrier capable but I presume heavier etc etc.

 

[FLYBOYJ]

Something from a boat building site:

Comparative Weights of Plywood, Aluminum and Steel

We are frequently asked if a design can be built in some other material than that noted. Any of our plans intended for planking with sheet material are designed to be a segment of a cylinder or a cone called “conendric” development. This usually means sections of the hull will be straight lines...

boatbuilders.glen-l.com

Now as indicated in the chart, the weight of aluminum will depend on what alloy type of aluminum we're talking about. 2024 will generally be lighter than 7075 but heavier than 6061. Here's some information on this;

Aluminum alloys for aerospace

A brief introduction (or refresher) on the lightweight metal’s history, applications, and future.

www.aerospacemanufacturinganddesign.com

 

[buffnut453]

Wouldn't that be the Hornet?

Hornet used the same construction techniques as the Mossie. A pair of original Hornet fuselage formers lie outside the entrance to the De Havilland Aviation Museum, London Colney.

 

[pbehn]

This isn't really meant to be a debate as to whether the Mosquito would be better off made of metal (it wouldn't, it'd tie up metal resources) more of a question as to how much a plane with the basic shape of the Mosquito would weigh if it was made of Aluminum alloy instead of wood for the overall ultimate load factor (8g), fuel and payload.

P pbehn S Shortround6 X XBe02Drvr

The use of "resources" was a redundant argument, workforce skilled in using wood is another issue. The UK didnt have much aluminium but it didnt have much balsa either, it had to be imported. In my opinion there wouldnt have been much difference in weight, if any at all. The Mosquito was light because it was a bomber with a small bomb load, a two man crew and no defensive armament. Also just in my opinion it was comparable to the P-51 in aerofoil, Meredith effect/cooling drag and overall aerodynamic cleanliness. Give NAA the job of making a metal one and you may get a metal one that is even better.

 

[GregP]

Something from a boat building site:

Comparative Weights of Plywood, Aluminum and Steel

We are frequently asked if a design can be built in some other material than that noted. Any of our plans intended for planking with sheet material are designed to be a segment of a cylinder or a cone called “conendric” development. This usually means sections of the hull will be straight lines...

boatbuilders.glen-l.com

View attachment 670859

Now as indicated in the chart, the weight of aluminum will depend on what alloy type of aluminum we're talking about. 2024 will generally be lighter than 7075 but heavier than 6061. Here's some information on this;

Aluminum alloys for aerospace

A brief introduction (or refresher) on the lightweight metal’s history, applications, and future.

www.aerospacemanufacturinganddesign.com

Yeah, but most aircraft skins are anywhere from .032" to .040" thick, not 1/8 (.125). Not too sure what thickness wood was actually used on a Mosquito. Interesting.

There WAS a post WWII aircraft that was VERY Mosquito-like, build of Aluminum. It was the FMA I.Ae.30 Nancu.

It had a pair of Merlins, was faster than any Mosquito, and empty, was 13,686 lbs. Loaded was 16,755 lbs. Max speed 460 mph. Cruise 310 mph. Population was 1 with 2 unbfinished, but it was close to a Mosquito in size and mission ... at least the fighter missions.

 

[Deleted member 68059]

This isn't really meant to be a debate as to whether the Mosquito would be better off made of metal (it wouldn't, it'd tie up metal resources) more of a question as to how much a plane with the basic shape of the Mosquito would weigh if it was made of Aluminum alloy instead of wood for the overall ultimate load factor (8g), fuel and payload.

P pbehn S Shortround6 X XBe02Drvr

This is always a tremendously difficult question to solve on any topic, I heartily recommend to you a book by J. E. Gordon called "The New Science of Strong Materials." It is very light reading and is a "popular science" book which requires no special training at all to appreciate, but will give you a dramatically better understanding of materials and structures. Its on the required reading list for almost all good 1st year engineering courses.

Amazon product ASIN 0140135979
View: https://www.amazon.co.uk/dp/0140135979/
Gordon reflects that it was "one of Gods little jokes" that the SPECIFIC stiffness of virtually all usable structural materials is nearly identical.

Surprisingly it is stiffness which oftern governs structural design, not strength. This number can only be improved upon by using VERY advanced non-homogenious
materials such as carbon or glass composities and cermets. (although technically woods are fibre composites...hence how they manage to "cheat" and Spruce beats Titanium!, which is at a disadvantage being a homogenious material - ie. it has the same composition throughout, whereas woods have very strong fibres held in place by a relatively weak matrix, matrix being the clever word for the "glue" that holds the strong fibres in an orientation such that their strength in tension is utilised, even the most advanced carbon fibre is essentially just "floppy yarn" until its held in place by the resin)

Specific Stiffness (Youngs Modulus per Unit Density, m^2 s-2 x 10^6)

Wrought Iron 26
Sitka Spruce 26
Steel 25
Aluminium 26
Titanium 25
Magnesium 26
Balsa 25
Pine 20

Wing flexure or fuselage twist would be two key metrics which essentially would produce an aircraft of exactly the same weight regardless of if they were made of iron or balsa wood !
(it is a little more complicated than that due to bucking in very thin sections, but the general principle is such)

 

[gumbyk]

Yeah, but most aircraft skins are anywhere from .032" to .040" thick, not 1/8 (.125). Not too sure what thickness wood was actually used on a Mosquito. Interesting.

Fuselage is around 1/4" from memory. But, that's a sandwich of ply and balsa. From a subjective point of the panels I lifted, I didn't find them much different to what I would have expected from an aluminium one. But, that's only panels, and my highly uncalibrated arm...

 

[Crimea_River]

That book was recommended to me by a university prof 40 years ago and I think I still have it somewhere - an excellent read.

As to the plywood thicknesses on the Mosquito, it ranged from 1.5 to 3mm on the fuselage and up to I think 5mm on the mainplane. Of course, the fuselage had an inner skin, typically 1.5mm thick, and an outer skin of varying thicknesses and grain patterns separated by 7/16 inches of balsa filler.

There was a thread on this topic a few years back. Metal Mosquito built massively in the US
And, somewhat related: What if the P-38 was made of plywood a la Mosquito?

 

[SaparotRob]

P-39 made of wood?

 

[pbehn]

P-39 made of wood?

winner in all theatres.

 

[pbehn]

This is always a tremendously difficult question to solve on any topic, I heartily recommend to you a book by J. E. Gordon called "The New Science of Strong Materials." It is very light reading and is a "popular science" book which requires no special training at all to appreciate, but will give you a dramatically better understanding of materials and structures. Its on the required reading list for almost all good 1st year engineering courses.

Amazon product ASIN 0140135979
View: https://www.amazon.co.uk/dp/0140135979/
Gordon reflects that it was "one of Gods little jokes" that the SPECIFIC stiffness of virtually all usable structural materials is nearly identical.

Surprisingly it is stiffness which oftern governs structural design, not strength. This number can only be improved upon by using VERY advanced non-homogenious
materials such as carbon or glass composities and cermets. (although technically woods are fibre composites...hence how they manage to "cheat" and Spruce beats Titanium!, which is at a disadvantage being a homogenious material - ie. it has the same composition throughout, whereas woods have very strong fibres held in place by a relatively weak matrix, matrix being the clever word for the "glue" that holds the strong fibres in an orientation such that their strength in tension is utilised, even the most advanced carbon fibre is essentially just "floppy yarn" until its held in place by the resin)

Specific Stiffness (Youngs Modulus per Unit Density, m^2 s-2 x 10^6)

Wrought Iron 26
Sitka Spruce 26
Steel 25
Aluminium 26
Titanium 25
Magnesium 26
Balsa 25
Pine 20

Wing flexure or fuselage twist would be two key metrics which essentially would produce an aircraft of exactly the same weight regardless of if they were made of iron or balsa wood !
(it is a little more complicated than that due to bucking in very thin sections, but the general principle is such)

I presume the question was whether you could make what you want, at the time from a given material. The Spitfire had steel wing spars (later stainless steel), but it was a pair of spars of nested construction, put together with a lattice strapping them together and a "D" shaped leading edge to reinforce it, as you said a structure, not just a material choice.

 

[wuzak]

There WAS a post WWII aircraft that was VERY Mosquito-like, build of Aluminum. It was the FMA I.Ae.30 Nancu.


View attachment 670877

It had a pair of Merlins, was faster than any Mosquito, and empty, was 13,686 lbs. Loaded was 16,755 lbs. Max speed 460 mph. Cruise 310 mph. Population was 1 with 2 unbfinished, but it was close to a Mosquito in size and mission ... at least the fighter missions.

Very much like the Hornet, not so much like the Mosquito.

 

[wuzak]

The use of "resources" was a redundant argument, workforce skilled in using wood is another issue. The UK didnt have much aluminium but it didnt have much balsa either, it had to be imported. In my opinion there wouldnt have been much difference in weight, if any at all. The Mosquito was light because it was a bomber with a small bomb load, a two man crew and no defensive armament. Also just in my opinion it was comparable to the P-51 in aerofoil, Meredith effect/cooling drag and overall aerodynamic cleanliness. Give NAA the job of making a metal one and you may get a metal one that is even better.

Materials wise, I don't think there was an issue with building the Mosquito out of aluminium.

But did de Havilland have the production facilities to produce aluminium Mosquitoes?

de Havilland was inexperienced with the use of aluminium structures. They had just made the all-metal Flamingo, but did not make many.

 

[pbehn]

Materials wise, I don't think there was an issue with building the Mosquito out of aluminium.

But did de Havilland have the production facilities to produce aluminium Mosquitoes?

de Havilland was inexperienced with the use of aluminium structures. They had just made the all-metal Flamingo, but did not make many.

I dont know, but Supermarine didnt have any experience of making planes out of Duralumin until the Spitfire was ordered. Neither did Hawkers, the Hurricane was mainly made from "dope" until 1940.

 

[special ed]

A balsa P-39 should easily reach 40 to 45 thousand feet. The tumbling and spin problems would be less violent, more like a falling leaf. My balsa flying model proves this.

 

[wuzak]

I dont know, but Supermarine didnt have any experience of making planes out of Duralumin until the Spitfire was ordered. Neither did Hawkers, the Hurricane was mainly made from "dope" until 1940.

And the inexperience of Supermarine slowed the transition from prototype to production.

 

[Shortround6]

Man, I get chewed out for anti British bias?

"Much of the airframe was composed of alclad, while detailed fittings were fabricated from stainless steel; metallic objects were anodised as an anti-corrosion measure. While the hull a sheet metal covering, the wings were covered with fabric"

This dates back the Southhampton series

"The Southampton's structure was revised substantially over successive batches. The Southampton Mk I had both its hull and its wings manufactured from wood, while the Southampton Mk II had a hull with a single thickness of metal (duralumin) (the Mk I had a double wooden bottom); this change gave an effective weight saving of 900 lb (410 kg) (of this 900 lb, 500 lb (230 kg) represented the lighter hull, while the remaining 400 lb (180 kg) represented the weight of water that could be soaked up by the wooden hull) allowing for an increase in range of approximately 200 mi (320 km).[7]​ All metallic elements were anodised to deter corrosion. During 1929, 24 of the Southampton Mk Is were converted by having newly-built metal hulls replacing the wooden ones.[7]​ Later on, the type was also furnished with metal propellers produced by Leitner-Watts.[9]​ Some of the later aircraft were built with metal wings and were probably designated as Southampton Mk III, although this designation's usage has been disputed."

There was an intermediate stop The Supermarine Scapa

The Scapa hull was an all-metal structure, while the wing and tail surfaces had metal structure with fabric covering.

Making water tight flying boat hulls is a lot different than making land planes but the Spitfire was a long long way from being Supermarine's introduction to metal construction.

 

[Reluctant Poster]

I presume the question was whether you could make what you want, at the time from a given material. The Spitfire had steel wing spars (later stainless steel), but it was a pair of spars of nested construction, put together with a lattice strapping them together and a "D" shaped leading edge to reinforce it, as you said a structure, not just a material choice.

According to Haynes the spars are aluminum not steel.

Read all about it

Haynes Book Division's senior commissioning editor, Jonathan Falconer explains how its manuals provide a unique insight into how the designers of iconic aircraft have embraced technology developments in aviation.

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