Mosquito gets finishing touches

[JDK]

There's money, if not restorations to be made from rumours of warbirds...

I remember reading that either the Hornets or Sea Hornets were retired primarily due to delaminating wood. Perhaps in Wings or Airpower magazine 30-35 years ago?

I've checked a couple of other references, and not found anything, but I don't have much in technical detail on the Hornet.

Part of the problem is nationalistic; British and Commonwealth accounts tend to underplay issues with DH failures and problems, while foreign - particularly US accounts - are prone to over-emphasising 'issues' with the wooden construction due to its contextual strangeness.

Regards,

[JDK]

As far as I can see, RAF Hornets were retired in favour of (jet) Vampires* in Malaya while Sea Hornets became obsolete. Better info welcome!

David Collins, perhaps 'the' Hornet expert, said on the Key forum:

Originally Posted by CIRCUS 6:

The later dH 103Hornet was withdrawn owing to delamination when operating in the humid Far East.

Kurt
The type of flying they did was actually the key factor - very frequent diving at low level, pulling excessive G's. Most of these Hornets were at the end of their useful lives anyway, being up to 7 years old.

Yes, heat and humidity didn't help, but this was not the key failure mode. By the time Hornets were deployed in Malaya, special UV coatings had been developed for the fabric to keep structural temperatures down.

http://forum.keypublishing.co.uk/showpo ... ostcount=8

An interesting couple of negative pieces of evidence and those rumours on PPrune:
http://www.pprune.org/archive/index.php/t-236191.html

Regards,

* And Vampires have a wooden sandwich fuselage 'pod' of essentially the same construction and the Mosquito / Hornet though I think the Hornet had a more advanced wood-metal bonding process - not sure on that though.

[Dave Homewood]

Considering the vital ingredient in restoring Mosquitoes has been the moulds built by Glyn Powell, your mention James of the Vampire fuselage being built the same way makes me wonder whether there are any Vampire or Venom moulds still in existence? Does anyone rebuild them?

[JDK]

I'm not aware of any moulds, Dave, and all the Vampire restorations I've heard of weren't back to requiring a new pod, just patches, or section repair. But it's not an area I'm particularly knowledgeable about.

[bdk]

I believe the Vampire has a steel frame underneath to handle the structural loads and the wooden components are primarily the aerodynamic fairing around the cockpit (and act as the pressure compartment).

[JDK]

I believe the Vampire has a steel frame underneath to handle the structural loads and the wooden components are primarily the aerodynamic fairing around the cockpit (and act as the pressure compartment).

I really don't know where these myths come from, except that there's clearly some deep suspicion of wood as a high-capability structural element. (I'm sure bdk knows this and is just repeating canards he's heard in the engineer's lunchroom)...

From the armour bulkhead behind the nose cone, forward of the cockpit, to behind the gun ammunition bay aft of the cockpit, the Vampire fuselage pod is an all wooden monocoque 'sandwich'. There is no main metal structural members.

From David Watkins' de Havilland Vampire, the Complete History:

The airframe was a composite construction, having both wooden and metal components in its structure. The wooden section comprised that part of the fuselage extending from bulkhead no. 1 to bulkhead no. 4 at the rear, with the remainder of the aircraft being of metal construction. This form of composite construction not only served to reduce weight and improve performance, but also, coincidentally, conserved cockpit warmth; it had been developed by the company in 1937 for the four-engined DH 91 Albatross airliner and was later successfully employed in the Mosquito and Hornet fighters.

He goes on to describe the construction method, which, more briefly, is in two half sections, where a layer of birch ply laid over a male wood or cement mould, and then built up with spruce insets (acting like stringers and frames) and the gaps filled with Balsa or Quipo wood, after which another layer of birch ply was laid over, each layer being glued, pinned and held in place by steel bands while it cured. Afterwards sanding back, a layer of Madapollam fabric was used as a final covering and took the Aluminium dope for UV and other protection, and then the appropriate camouflage.

This wooden structure had the four 20mm cannon barrels under the cockpit, with the breeches behind and the ammunition tanks above. Bulkhead 1 had a hefty piece of armour plate, and all this, plus the cockpit pressurisation and the (later) insertion of a Martin Baker ejection seat in some models, was entirely supported by the wooden structure described above.


Here's a photo of the Vampire under static restoration at The Old Aeroplane Co, Tyabb, Victoria, Australia. The tan and green areas are the wooden structure, the metal fairings on the nose and wing root are light aluminium forms, no structural load.


My favourite piece of disinformation about wooden warbirds was a comment by a poster here that:
"BTW. the engine is mounted to an oak beam behind the wood pod."


Bruce, "DH Guru" (IMHO) posted this in that thread later:

The engine mount is NOT wood, it is steel. The engine mounts are attached to the carry through spars, which I grant you are bolted to the wooden fuselage. However, the carry throughs are steel, and are the heart of the aircraft. In effect, the engine is bolted to the wing, rather than the fuselage.

Lets be clear about what the fuselage does - it is basically a fairing that encloses the pilot. The important bits are the cockpit floor, and the bulkhead just forward of the tank bay. If you get problems in those areas, then its not looking good!

http://warbirdinformationexchange.org/p ... 2&start=30

And those bulkheads are wood.

Regards,

[bdk]

James, you've squashed me! A friend of mine has/had a Vampire and I thought what I said was so based upon my obviously faulty observations of the actual aircraft. Maybe I'm thinking of behind the cockpit where the engine mounts? I don't know what I remember anymore!

[JDK]

James, you've squashed me!

Whoops, no squashing intended! I just work on the basis that without data, it's just opinion, and they're legion...

I should add that most of what I post is just learning, usually from others who've answered a lot of damnfool questions - then I pass them on later, when a poor, innocent works from memory...

A friend of mine has/had a Vampire and I thought what I said was so based upon my obviously faulty observations of the actual aircraft. Maybe I'm thinking of behind the cockpit where the engine mounts? I don't know what I remember anymore!

Could be; aft of the wing spar fuselage junction, there's a more conventional tubular-based metal structure. Even de Havilland thought surrounding a jet engine with a wooden structure might be a bad idea...

Anyway, as one WIX member put it, it's JDK's "bucket 'o words" and another enjoyed the Oshkosh fundofacts experience.

Regards,

[Dave Homewood]

Keep bucketing those words out of your well of knowledge James, they're always appreciated.

[bdk]

I know have it on good authority that a Mosquito in made from paper mâché and is pop riveted together.

I'm on a roll!

[JDK]

I know have it on good authority that a Mosquito in made from paper mâché and is pop riveted together.

Those would be 'modern beat combo rivets', Brandon.

[JohnH]

I know have it on good authority that a Mosquito in made from paper mâché and is pop riveted together.

I'm on a roll!

Yea and they bought the pop rivets from the mastermind of "The Defender". !!!

[Red Baaron]

I wonder why they aren't getting Kermit Weeks to test fly this airplane? I'm sure the two pilots they have chosen are qualified, competent guys but it sure seems to me that they would go with experience in the type. Considering that Kermit is probably the only guy left around today that is still flying and has flown a Mosquito, it looks like they would go with him. Just the fact that he has flown one makes him more experienced than anybody that hasn't.

[Mark Allen M]

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Last edited by Mark Allen M on Sat Sep 08, 2012 12:38 pm, edited 2 times in total.

[Red Baaron]

I'm sure the two pilots they have chosen are qualified, competent guys

I think you just answered your own question. I believe I read here somewhere that the test pilots are already on board and ready to go when testing begins.

I don't doubt they are capable of doing it and it sounds like the guys that were selected are first rate. I was just wondering why they don't get a guy who has actually flown that type of airplane? Kermit has, they haven't as far as I can see.