All metal Mosquito ??

[glider1]

Originally Posted by Graham Boak

As an aside, and from direct personal experience, the rivalry between HP and DH was so intense that I'm rather surprised that HP made any bombracks for DH, even under wartime conditions. As the bulged bombbay was no longer than the original, which could only take 4x500lb if the fins were shortened, are you describing some kind of triple rack? The usual carriage of 6x500lb would be with 2 underwing.

The later Mosquito day bombers were not escorted by Mosquito fighters - the Mosquito was not employed as a day or escort fighter, not least because of its inability to fight with single-engine fighters. The Mosquito made a superb night fighter, and heavy fighter for Coastal Command, but not where enemy fighter opposition could be expected. For longer-range missions, Mustangs were available which could comfortably exceed the range of the FB Mk.VI, but 2TAF did not fly deep daylight penetrations.

The Mosquitos were indeed flying missions with deeper penetration than the Blenheims, but they were employed as a direct replacement. The point is that such missions, however spectacular from the propaganda point of view, resulted in unacceptable losses. As indeed did similar US attempts with the B-26.

Briefly
Yes they were triple bomb racks and there were times when Mosquito's were used as the escort, normally they were Typhoons or Mustangs. It wasn't common but it did happen.

I will comment later on losses.

[MarkRS]

Originally Posted by Six Nifty .50s

As a side note, nearly all wartime fast patrol boats and subchasers were mainly of wooden construction.

Even further aside, the Admiralty supplied the plans for wooden fast patrol boats to the Russians who in turn were supplying them to other countries at least into the 1980s. Vosper Thornicroft fitted out at least 6 fpts with modern weapon systems and a fibreglass skin on the hull.

[Kutscha]

Originally Posted by MarkRS

Actually the average density of Balsa wood is 170 kg/m3 which is far less than Aluminium at 2700 kg/m3. Even when you take into account that Balsa is far weaker than Aluminium, The strength to weight ratio of Balsa is about 40% better. So an Aluminium Mosquito would have been heavier and slower.

Weight of a 24" x 60" panel:

Aluminum alloy - 0.91lb (0.063" #26 and #27)

Balsa sandwich - 10.2lb (2 x 1/8" plywood + 1/4" balsa @ 8lb/cf)

Australian propaganda video
http://www.youtube.com/watch?v=c7cVvYdLeek

[MarkRS]

Originally Posted by Kutscha

Weight of a 24" x 60" panel:

Aluminum alloy - 0.91lb (0.063" #26 and #27)

Balsa sandwich - 10.2lb (2 x 1/8" plywood + 1/4" balsa @ 8lb/cf)

Australian propaganda video
http://www.youtube.com/watch?v=c7cVvYdLeek

The weight of the balsa sandwich is about right, but the aluminium calculation is 10x out. Should be 9.1lb. And you are not calculating like with like or calculating what was available in 1940. Aluminium composites were not in use. Wood composites were. An unstiffened sheet of aluminium that size 1/16" thick would weigh 9.5 lb by itself.
The ratio also changes if you make the plywood thinner and the balsa thicker. For example 1/16" ply and 1/2" balsa comes out to about 8lb and is probably stronger.
Today, if you want to go really light, you use epoxy graphite with a protective surface of Kevlar against impact damage.

[Kutscha]

Right, I messed up.

A 0.0641" sheet (2'x5') of aluminum weighs 9.3lbs according to the Machinery's Hand Book.

Sure it is like with like, as that is the skin of the a/c.

More research has turned up, 1/16" and 5/64" plywood and 7/16" balsa.
http://users.skynet.be/BAMRS/dh103/f...nstruction.htm

So as you say 8lb or a little less.

[Bill Walker]

Sorry, but it is clearly not like with like. An aluminum skin of that thickness needs lots of frames and stringers behind it for stiffness and out of plane loads, the wood composite needs much less back up structure, and no mechanical fasteners. Besides the weight of the frames and stringers, there is considerable time required for assembly, and many chances for error in installing the fasteners - these become crack starters and shorten the fatigue life considerably. That is one of the big advantages of composites (wood or otherwise) over fabricated metal.

I'm surprised that no one has mentioned one of the biggest draw backs to wooden structures - environmental deterioration of the wood and glue. The RCAF learned this the hard way, watching the Oxfords, Ansons and Cranes in the BCATP literally dissolve in the Canadian winters when they were not meticulously maintained. It is interesting to note that when the RCAF established several reserve light bomber squadrons right after the war they could choose between two light bomber fleets already paid for and stored in Canada: several hundred brand new or nearly completed Mosquitoes at Downsview, and about 50 well used B-25s left over from 5 OTU on the west coast. The Mosquitoes were all sold or scrapped within a few years, the B-25s carried on in RCAF service until the early 1960s.

I'm also surprised nobody has mentioned a more direct comparison: the wooden fuselage Spitfire tested during the war, using Mosquito fabrication techniques. Maybe somebody could dig up some figures on that project?

[MarkRS]

Check out the claims for this wooden Spitfire! I want one, but my wife won't let me!

http://www.spitfirebuilder.4t.com/catalog.html

Quote from the site:

"The use of both classic construction methods and the wood sandwich skins result in an aircraft that is a ton lighter than the original Spitfire Mk, IX, yet is stressed to 10G ultimate load. At 2,000 pounds lighter with the 1200 horsepower Allison V-12, the SAC Spitfire will easily outperform any original MkIX. Acceleration and rate of climb, will be nothing short of breath taking. Turning performance, maneuverability, low speed handling, and balanced field length will be noticeably better than an original metal Spitfire."

[MarkRS]

Another quote from the site:

"The beautifully rounded shape of the Spitfire's fuselage is built with the same "balsa-ply-balsa" sandwich construction technique as used on the famous De Havilland Mosquito, giving tremendous stiffness and strength, but a lot less weight than metal."

I rest my case.

[Kutscha]

So this wooden Spitfire IX has a tare weight of 3800lb.

[Bill Walker]

The aeronautical equivalent of vapourware.