There is typical and then there are exceptions, the Hurricane didn't even start off as a stressed metal fighter.
DH Mosquito Design Analysis
- Thread starter MIflyer
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Crimea_River
Marshal
The thicknesses shown in the photograph in post 28 aren't entirely correct. Herman1rg's description in post 29 is correct but what is omitted is that both the outer and inner plywood skins vary in thickness depending on where on the aircraft they are located. The only consistent thickness is the balsa and the various reinforcing pieces between the plywood, these being 7/16 inches thick (closer to 11mm than 12) but the plywood varies between 1.5 and 3mm in thickness. So, the over thickness of the fuselage does vary.
As a very young man talk of a "wooden aeroplane" led me to believe it was somehow cheap and substandard. It is actually just a different branch of advanced engineering. The QA/QC systems they used I find really interesting, I was always involved in metals, it is amazing that the work of metallurgists was rivalled with a natural product.
Crimea_River
Marshal
Well it's also amazing what they got away with. During restoration of RS700, in which I'm involved, we discovered that the two opposing halves of (I think) Bulkhead No. 4 were built differently. One had the plywood face plates screwed on and on the other they were all nailed.
Back to the original question, it is a common misconception that the Mosquito's speed was due to the "lightness" of the wood structure. In fact, the Mosquitos power to weight ratio was inferior to other types including the Spitfire. It's comparable speed was due more to a clean design with smooth surfaces that were facilitated by the wooden construction.
Back to the original question, it is a common misconception that the Mosquito's speed was due to the "lightness" of the wood structure. In fact, the Mosquitos power to weight ratio was inferior to other types including the Spitfire. It's comparable speed was due more to a clean design with smooth surfaces that were facilitated by the wooden construction.
Shortround6
Major General
The A-20 is probably the closest metal equivalent to the Mosquito both in size and timing.
With R-1830s it is a bit lighter and with R-2600s it is a bit heavier.
A metal Mosquito might have been a few hundred pounds heavier or a few hundred pounds lighter.
With R-1830s it is a bit lighter and with R-2600s it is a bit heavier.
A metal Mosquito might have been a few hundred pounds heavier or a few hundred pounds lighter.
Some compound curves and overall finish on the Mosquito would be hard to achieve in a mass produced metal plane. In some ways any photo or actual Mosquito looks like a model, there are no rivets and few seams.
You could say that, but you have to design a pressed structure. Producing a Blackburn Roc with a 50,000 ton press wont do much for its performance.
buffnut453
Captain
But putting a Blackburn Roc INTO a 50,000 ton press might save a few aircrew's lives.
I couldn't agree more, somethings just should never have happened.
Shortround6
Major General
The Rocs would never have made it to the press, in a perfect world it would have been too busy with Bothas 
buffnut453
Captain
Better yet, crash a Roc into a Botha and then put both of them in the press together. More efficient that way!
Spot on, Andy, which is one of the reasons it was made of wood in the first place. Text from the letter to Freeman by GdeH dated 20 September 1939, which outlines the company's plans that evolved into the Mosquito;
"...we believe that we could produce a twin engine bomber which would have a performance so outstanding that little defensive equipment would be needed. This would employ the well tried out method of design and construction used in the 'Comet' and the Albatross' and, being of wood or composite construction, would not encroach on the labour and material used in expanding the RAF. It is specially suited to really high speeds because all surfaces are smooth, free from rivets, overlapped plates and undulations. It also lends itself to very rapid initial and subsequent production."
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Reasonable point
What exactly do I enter?: What's the typical metal gauge thickness for an aircraft designed to pull some g-load that would go eventually to 8g ultimate?
I put that in and I'd get nothing
Okay, what would a plane of about the same size built for the same g-load as the Mosquito weigh in probably?
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Shortround6
Major General
see post #45
google is a search engine, not an engineering short cut.
but in something like "thickness of sheet metal gauges"
and you will get a lot of results, you might even try "weight of sheet metal gauges"
asking google to figure out G loadings is not a search engines job.
In my opinion (just an opinion) they would be about the same weight. However many things get confused in the discussion. The mosquito was fast and light for a bomber, but weight doesn't have a huge effect on speed. The P51 was heavier and bigger than a spitfire but also faster. DH had a lot of experience racing and using wood, the mosquito used wood, but also hade a very advanced cooling design, it used recently produced RAF aerofoil profiles, it had very smooth clean lines. If a company like North American were given the design brief of a small unarmed two seat bomber with two Merlin engines it would have come out about the same in performance, whatever difference in weight their was is actually of small consequence, how many designs have maximum weight as a criteria?
Shortround6
Major General
Zipper730 is trying to short circuit the engineering that goes into aircraft design.
as a very crude example let's design two simple tubes (fuselages) of semi- Monocoque construction and one that is full Monocoque.
totally made up numbers. do not try to fly these at home
Let's use a 30 foot length and a diameter of 4 ft (or a fraction under) so our circumference is 12.5 feet for a surface area of 375ft.
Now for our full Monocoque we find that we can use 14 gauge Aluminium at .905 lbs/sq/ft for a fuselage weight of 339.375lbs (let's assume weightless welding for this to keep it simple for now.)
For semi-Monocoque #1 we determine that we can use 24 stringers (L shape, T shape, U shape ?) and 7 frames/formers and use 18 gauge Aluminium at O.569 lbs/sq/ft for 213lbs of fuselage skin weight but how much do the stringers and frames weigh? and rivets or welding?
For semi- Monocoque #2 we determine that we can use 12 stringers (L shape, T shape, U shape ?) and 5 frames/formers and use 22 gauge Aluminium at 0.357 lbs/sq/ft for 133.875lbs of fuselage skin weight but how much do the stringers and frames weigh? they are now carrying most of the load. and rivets or welding?
Trying to compare skin thickness and weight simply ignores way too much.
as a very crude example let's design two simple tubes (fuselages) of semi- Monocoque construction and one that is full Monocoque.
totally made up numbers. do not try to fly these at home
Let's use a 30 foot length and a diameter of 4 ft (or a fraction under) so our circumference is 12.5 feet for a surface area of 375ft.
Now for our full Monocoque we find that we can use 14 gauge Aluminium at .905 lbs/sq/ft for a fuselage weight of 339.375lbs (let's assume weightless welding for this to keep it simple for now.)
For semi-Monocoque #1 we determine that we can use 24 stringers (L shape, T shape, U shape ?) and 7 frames/formers and use 18 gauge Aluminium at O.569 lbs/sq/ft for 213lbs of fuselage skin weight but how much do the stringers and frames weigh? and rivets or welding?
For semi- Monocoque #2 we determine that we can use 12 stringers (L shape, T shape, U shape ?) and 5 frames/formers and use 22 gauge Aluminium at 0.357 lbs/sq/ft for 133.875lbs of fuselage skin weight but how much do the stringers and frames weigh? they are now carrying most of the load. and rivets or welding?
Trying to compare skin thickness and weight simply ignores way too much.
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Crimea_River
Marshal
Monocoque.Not Monique
Also, just designing something in metal or wood doesn't automatically give a fixed weight. The Spitfire, Hurricane, P-51, P-40 and Bf109 (as Bouchon) all flew with Merlin engines and all had differing weights. If you design a wooden single engine fighter which weight would you compare to?
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