Were wooden Mosquitos more vulnerable than metal planes once they were hit

[buffnut453]

I've wondered what the Mosquito's life was when used in South East Asia with the constant dampness and heat. At some point the wood must have sucked up moisture.

There were problems when Mossies first deployed to the Far East, notably with ply delaminating. Interestingly, it seems the wood was less affected than the glue because using a stronger glue seemed to correct it.

I have no idea if there were longer-term issues but we should remember that most aircraft only lasted a few months at best during WW2, after which they'd either been shot down, crashed, worn out, or become obsolescent.

 

[Simon Thomas]

RAAF 87 PRU Squadron operated their PR-XVI Mosquitoes from 1944 to 1945 then from 1948 to 1953.
During the war they were operating from Northern Territory up to Borneo. After the war they operated all over Australia.
I can't say if they needed any rectification work during that time.

 

[yulzari]

I know from my experience playing guitar that wood can and does move in relation to both humidity and temperature swings. Both can stretch or shrink wood, a phenomenon we guitarists see when a guitar stored overnight in a room with poor atmospheric control requires retuning and then resettling before recording.

I don't doubt that the glues used in Mosquitoes were more resistant to this effect, and helped to stabilize the wood to a degree non-essential stuff (like playing a guitar) doesn't merit. But if the finish is only exterior, the interior wood may still vulnerable to weather effects and start delamination if the glue cannot cope with the variation in the wood per temp/humidity. If the glue cannot expand and contract with the wood, that may start a failure process.

This is obviously not a definitive answer, but only my own observations: unfinished wood breathes. It is mildly hygroscopic, but in hot, humid environments and under the stresses an airplane must endure, I can see how that might be problematic.

One must also note that metal aeroplanes move with changes in temperature as the metal expands and contracts. Important when a single flight may involve a ground temperature of +25 degrees and a maximum altitude of -60 degrees. This movement will not be uniform either with different thicknesses, shape, metal type and alloys.

The extreme is Concorde that lengthens by almost half a metre in the course of a flight. Moving from ground temperature to subsonic high altitude cold and then Mach2 heat friction, followed by the reverse on arrival.

 

[pb43]

Here is a link to a collection of pictures from a 1947 Aircraft Engineering article about how to repair the DeHavilland Mosquito that I photographed about 20 years ago, so apologies for the poor quality.

Aircraft Engineering 1947 article on the repair of the Mosquioto

I don't have the time to edit it myself, but if someone here feels inclined to edit it and repost it here as a pdf then that would be great.

If not, then download it while it's still there, since I have limited space in my Dropbox and I will probably remove it in a week or two.

RAR with jpgs and pdfs

 

[ThomasP]

In my notes, I have 'The airframe for the late-production Mosquitos are rated at 10 years airframe life, after which "significant additional" airframe inspection, maintenance, and repair would be required - probably including rebuild of major components. This airframe life does not take into account normal operational fatigue effects as those are considered under normal wear and deterioration of an airframe.'

However, it was also noted that 'In war-time it was not expected that any significant number of airframes would survive intact that long and not already be worn out from normal operations.'

The above was from a 1944 DH-Air Ministry memo. Sorry, but this is from 30+ years ago and I did not Xerox it at the time, just made the notes.

 

[don4331]

I'm surprised no one has pointed out the prototype for the Mossie's still existing; how many other WWII bomber prototypes still exist?

And you can see the repair to the tail done following the early testing accident.

Lastly, the prototype was re-engined with 2 stage Merlins later in its career and supposedly holds the title for fastest Mossie..

 

[Howard Gibson]

I've wondered what the Mosquito's life was when used in South East Asia with the constant dampness and heat. At some point the wood must have sucked up moisture.

Absolutely, they had problems. The original casein glue was not suitable for the tropics.

I met one of the guys from New Zealand's Avspecs at an airshow in Canad, and he claimed that the epoxy they are using should be good for a hundred years.

 

[Thumpalumpacus]

One must also note that metal aeroplanes move with changes in temperature as the metal expands and contracts. Important when a single flight may involve a ground temperature of +25 degrees and a maximum altitude of -60 degrees. This movement will not be uniform either with different thicknesses, shape, metal type and alloys.

The extreme is Concorde that lengthens by almost half a metre in the course of a flight. Moving from ground temperature to subsonic high altitude cold and then Mach2 heat friction, followed by the reverse on arrival.

All true in one sense, but Mossies aren't generating that much friction heat, nor is metal as sensitive to the temp/humidity changes involved. Comparing a supersonic Concorde made of metal to a very subsonic Mosquito made of wood is not really an apt comparison. I don't know the skin temps in flight of each type but I'd be willing to bet that 1200kts vs 360 is probably not useful in this context given the differences in construction etc.

Yes, metal also expands and contracts. But what is being discussed here is environmental, seasonal stuff, not operational and going from zero to shit-hot in 20 minutes. Metal doesn't respond to ground-level humidity and heat in the same way as glued wood. My guitar goes out of tune. My truck doesn't.

 

[yulzari]

All true in one sense, but Mossies aren't generating that much friction heat, nor is metal as sensitive to the temp/humidity changes involved. Comparing a supersonic Concorde made of metal to a very subsonic Mosquito made of wood is not really an apt comparison. I don't know the skin temps in flight of each type but I'd be willing to bet that 1200kts vs 360 is probably not useful in this context given the differences in construction etc.

Yes, metal also expands and contracts. But what is being discussed here is environmental, seasonal stuff, not operational and going from zero to shit-hot in 20 minutes. Metal doesn't respond to ground-level humidity and heat in the same way as glued wood. My guitar goes out of tune. My truck doesn't.

Indeed. I was not actually comparing Concorde with Mosquitos. It was just a tongue in cheek illustration of metal movement in aeroplanes by an extreme example. Metal does move, albeit rarely to a Concorde extent, and I was merely noting that internal airframe movement is reflected in metal aeroplanes as well as wooden ones. Different movements and from different causes but both wooden and metal aeroplanes are dynamic structures from causes other than aerodynamics.

 

[Shortround6]

My guitar goes out of tune. My truck doesn't.

People started using non-wood gun stocks in the late 50s (?).
At first because they were cheap. Later because they found that they didn't warp and go out of tune
I meet an Australian who had competed in rifle matches in South America. When I met him, his gun was using a cast aluminum stock (is that synthetic?)
He claimed that two days after he got off the plane in South America his old wood stock looked like a potato chip, prompting the search for a substitute stock material.
I met him 1987 and 1989. He and his teammates had cast aluminum stocks. I never saw the original wood or any photos.
Importing an American fiber glass stock would have been subject to a 100% import tariff at the time.
This also shows the effects of local conditions impacting design choices.

 

[MIflyer]

Relative to the vulnerability of Mossies. Here are two pictures of aircraft that got too close to exploding buzz bombs or aircraft. Note that the Mossie used fabric over the wood, not just painted wood, and that fabric as well as the fabric covered control surfaces were vulnerable to fire.

 

[SaparotRob]

Relative to the vulnerability of Mossies. Here are two pictures of aircraft that got too close to exploding buzz bombs or aircraft. Note that the Mossie used fabric over the wood, not just painted wood, and that fabric as well as the fabric covered control surfaces were vulnerable to fire.

View attachment 876026View attachment 876027

Yikes!

 

[marathag]

When did use of Butyrate dope take over from Nitrate in the RAF?

 

[MikeMeech]

When did use of Butyrate dope take over from Nitrate in the RAF?

Hi
There were problems with various aspects of 'dope' and how it was produced which came up much earlier than WW2. There is detail on this in the 'The Official History of The Ministry of Munitions' Volume XII, which is reference WW1:

I hope that is of interest.

Mike

 

[MikeMeech]

Hi
Continuing on from my previous post and moving into the late 1930s, the part work 'Aero Engineering Volume II Production' mentions the following reference 'dope':

This mention the two main types of dope then in use; 'cellulose nitrate' and 'cellulose acetate'. More information can be found in 'Aircraft Materials and Processes' by George F Titterton (of Grumman Aircraft), Pitman, New York, revised edition 1941:

This is probably the same information as found in the 1937 first edition so about the same period as the previous source. From this it appears the British are 'mainly' using the more "fire resistant" (and more expensive) type of dope at that time.
I hope that is of use.

Mike

 

[Dimlee]

Fire-resistant dope?
Muddy Waters would not approve.
"...there should be no law
On people that want to smoke a little dope"
(Champagne & Reefer)

 

[SaparotRob]

Could use some Moët et Chandon Brut Imperial right now.

 

[buffnut453]

Could use some Moët et Chandon Brut Imperial right now.

In a pretty cabinet, perchance?

 

[SaparotRob]

In a pretty cabinet, perchance?

Nah, straight from the bottle is fine.

 

[buffnut453]

Nah, straight from the bottle is fine.

You're a class act, brother!!!!