Mosquito vs The Rest

[fastmongrel]

Why do some people call the DH Mosquito the Moskito surely the Moskito is the TA 154

 

[mhuxt]

Every time I click on this thread I get an ad trying to sell me fly screens/mozzie screens.

 

[FLYBOYJ]

I only cited two squadrons out of the many that used Mosquitos, some in some of the most hostile weather/climate conditions imaginable: eg: 2 TAF operated Mosquitos during the winter of 1944-45 - one of the worst on record; Coastal Command units had to operate the Mosquito in a salt water environment while operating out of some pretty bleak airfields

As long as there is a consistency in temperature/ moisture there is no problem, it when you have a wood aircraft operating in an environment (like Europe) and you move it to a place that is really hot or hot and humid.

Which runs to 28 pages...And here's a little info about maintenance and repair of metal structures - 114 pages, 34 of which are devoted to equipment needed.

http://www.faa.gov/regulations_poli...raft/amt_airframe_handbook/media/ama_Ch04.pdf

I know those pages well, it shows shop and fabrication equipment, use of tools and processing equipment (some of the same equipment used on wood aircraft). Because there are more metal aircraft flying today than there are wood, that textbook emphasizes on metal structural repair. I don't understand your point, are you trying to say that because there are more pages in this book written about repairing metal airplanes that it's harder than working on wood airplanes?

"Never judge a book by its cover - or the amount of its pages."

 

[Kryten]

wood being cellulose absorbs moisture and swells, if you build a Mossie on a wet humid day in the UK then fly it to Egypt, it's not rocket science that its going to suffer some shrinkage as it dries out!

I'm unclear exactly how much tolerance would be built into the design to cover that however, and i'm pretty sure the guys who design these things already considered and tested this and the main frame all being wood should have a similar absorption/dessication rate?

repairing a sandwich is not simple either as if you just square off the hole and patch it your introducing a stress raiser at the joint, I would think whole panels would have to be replaced to maintain the stiffness?

 

[FLYBOYJ]

I'm unclear exactly how much tolerance would be built into the design to cover that however, and i'm pretty sure the guys who design these things already considered and tested this and the main frame all being wood should have a similar absorption/dessication rate?

I believe some aircraft do have that calculated. On wood aircraft I've worked on what I have found is shrinkage at metal fittings that are attached to the wood structures. At areas as such you are inspecting for looseness and you would tighten or re-adjust where possible, hopefully without cracking or splitting the wood structure.

repairing a sandwich is not simple either as if you just square off the hole and patch it your introducing a stress raiser at the joint, I would think whole panels would have to be replaced to maintain the stiffness?

It depends how deep the damage is, its location and if it goes completely through the structure. Sometimes you could plug holes with glue impregnated plugs and reinforce on the interior side of the structure. Usually manufacturers will come up with a "Standard Repair Manual" or SRM that will detail "allowable" repairs.

 

[stona]

wood being cellulose absorbs moisture and swells, if you build a Mossie on a wet humid day in the UK then fly it to Egypt, it's not rocket science that its going to suffer some shrinkage as it dries out!

Do you have any evidence for that or are we in the realms of supposition?

As someone has already pointed out the de Havilland Mosquito was not made from wood but a composite material containing, amongst other things, two or three types of wood.

Cheers

Steve

 

[FLYBOYJ]

Do you have any evidence for that or are we in the realms of supposition?

How about information from people who worked on wood aircraft?

As someone has already pointed out the de Havilland Mosquito was not made from wood but a composite material containing, amongst other things, two or three types of wood.

Cheers

Steve

Gotta disgaree, go to my earlier post - wood is wood, you could call is "composite wood" meaining that you have several types of wood making up the structure, but it is still wood, and we don't count adhesives or things that are "bolted on."

As mentioned earlier "In the composite world today the rule of thumb is when there is 30% or more of another material (fiberglass/ Kevlar or fiberglass/ graphite for example) we call it composite. The glues and resins are normally not considered."

 

[tyrodtom]

I'm not well acquanted with wooden aircraft, but I am with wooden canoes. Hasn't anyone ever heard of varnish, not that's what's used on modern canoes.
But I started to buy a parlty compleleted homebuilt several years ago. A Pietenpol, wooden construction, a late 20's design, all wood structure. All the wood was covered with polyurethane varnish.
Regular varish has been around for hundreds of years. They surely didn't just put protectrant on the outside surface of those wooden aircraft.
I've seen well maintained wooden canoes last in use, 50 years, they're family heirlooms.

 

[FLYBOYJ]

I'm not well acquanted with wooden aircraft, but I am with wooden canoes. Hasn't anyone ever heard of varnish, not that's what's used on modern canoes.
But I started to buy a parlty compleleted homebuilt several years ago. A Pietenpol, wooden construction, a late 20's design, all wood structure. All the wood was covered with polyurethane varnish.
Regular varish has been around for hundreds of years. They surely didn't just put protectrant on the outside surface of those wooden aircraft.
I've seen well maintained wooden canoes last in use, 50 years, they're family heirlooms.

Canoes generally remain in a constant temperate. Think of the temperature changes from ground level to altitude let alone changes in relative humidity. Varnish helps the exterior but only for so long, you can still pick up shrinkage, dry rot and other not so desirable conditions

 

[Kryten]

Do you have any evidence for that or are we in the realms of supposition?

As someone has already pointed out the de Havilland Mosquito was not made from wood but a composite material containing, amongst other things, two or three types of wood.

Cheers

Steve

well, in it's simplest form, how about a door that swells and sticks when the weathers wet?

wood absorbs moisture, that's an undisputable fact, the interesting part of the Mossie construction would lie in the relative expansion of the differing woods, bear in mind the ply outer skin would be subjected to a greater degree of humidity than the balsa sandwich sealed away between the two skins, I really don't believe this would be ignored by people who can design loading and stressing of an airframe, it must be designed in and as such I think the Mossie construction is simplicity and brilliance combined!

I built my own race cars a few years back and used sandwich construction to build the tubs, we wanted to use alloy skins with alloy honeycomb as the filler, but, as ever funding constrained us as the cost of the resin and materials exceeded our budget, we ended up using alloy skins with polyurethane foam sheet as the filler, it was only slightly heavier than the honeycomb yet was still immensely stiff!

When you first mess around with sandwich constructions you are subjected to a real eye opener in regard to strength to weight, ending up with much thinner materials than you ever thought possible to achieve the strength, the mossie and it's ilk are the ancestors of the construction techniques used today on all aircraft from airliners to fast jets, it's a marvellous design !

 

[Balljoint]

Similarly in metal skinned aircraft, the skin takes most of the loads. The skin requires stiffening ribs to prevent it from buckling too. To make the skin thick enough to resist buckling would make it extremely heavy.

A bit after the fact, but that's why honeycomb aluminum is used to provide light-weight volume between load-carrying skins.

 

[tyrodtom]

I've increased the strength of some thin wall tubbing just by drilling small holes and filling them full of structual foam.
It surprized me how much it added to it's bending resistance.
In racecar fabrication, we'll often fill a tube full of sand, to keep it from collasping when we bend it at extreme angles.

 

[altsym]

Not for me, tubs for example I just roll in simple stiffening ribs onto the sheet. Same with floor pans. Super strong super light is the end result.
And as for building wood fences.. wood does not like to go from hot to cold to hot, warping and such will happen. And that's fencing wood (fur, pine, etc.). Never mind plywood. Wetness in this case is your enemy. Balsa seem to be really temperature resistant (20 year building RC aircraft), water though, forget about it.

 

[Glider]

Whatever the repair and maintanence issues that may or may not be a factor in using wood in the construction. The fact remains that the Vampire/Venom also had a fair amount of wood in their construction, they were built in large numbers and served all over the world. So its safe to assume that the the problems around the use of wood had been resolved.

 

[FLYBOYJ]

Whatever the repair and maintanence issues that may or may not be a factor in using wood in the construction. The fact remains that the Vampire/Venom also had a fair amount of wood in their construction, they were built in large numbers and served all over the world. So its safe to assume that the the problems around the use of wood had been resolved.

AFAIK only on some of the forward fuselage access doors and non-structural members in later models. I believe just the fuselage of the earlier models were made from wood.

 

[stona]

wood is wood, you could call is "composite wood" meaining that you have several types of wood making up the structure, but it is still wood, and we don't count adhesives or things that are "bolted on."

How can you not count adhesives or resins etc? A piece of carbon fibre mat is about as structural as a piece of newspaper until you construct it in bonded layers to give a material with entirely different properties. Exactly the same applies to the wood composite used to construct the Mosquito.

The original proposition is that wood being cellulose absorbs moisture, which is generally true, but has little to do with the construction of the Mosquito. I wasn't asking for some evidence that wood absorbs moisture but rather for evidence that this was a problem for the materials used by de Havilland.

Cheers

Steve

 

[FLYBOYJ]

How can you not count adhesives or resins etc?

You don't unless you're talking pre-preg fabric, and even then the dominat construction material is always made reference to as the main structural component.

A piece of carbon fibre mat is about as structural as a piece of newspaper until you construct it in bonded layers to give a material with entirely different properties Exactly the same applies to the wood composite used to construct the Mosquito.

And at the end of the day that Carbon fibre is "carbon fibre" as at the end of the day the Mosquito is constructed of "wood."

The original proposition is that wood being cellulose absorbs moisture, which is generally true, but has little to do with the construction of the Mosquito. I wasn't asking for some evidence that wood absorbs moisture but rather for evidence that this was a problem for the materials used by de Havilland.Cheers

Steve

In the end ALL wood, be it from a deHavilland aircraft (Mosquito) or any other mnufacture will have the potential to absorb moisture or shrink. I cannot find the original article but because of wood shrinkage, the IDF got rid of their Mossies after the Suez crisis as they were becoming harder to maintain. I do believe that DeHavilland probably had the best processes to ensure that any natural degadation of the wood was minimized, but in the end you'll only be able to do so much to a wood structure, especially if you're using it in a military application.

 

[stona]

In the end ALL wood, be it from a deHavilland aircraft (Mosquito) or any other mnufacture will have the potential to absorb moisture or shrink.

Yes ...... but having the potential to do and doing something are not the same thing. Many things can absorb moisture and most can be treated to prevent it.

I'm not suggesting that there might not be some problems of degradation specific to wood or wood composites, just as there are those specific to metal structures (heaven knows how many gallons of zinc chromate were applied to US aircraft of the period). I just haven't seen any evidence that moisture absorption was a problem for the materials used in the de Havilland Mosquito.

I don't know if it was a problem or not which is why I asked in the first place. I will not assume that it was on the grounds that wood was used in the construction process

Cheers

Steve

 

[fastmongrel]

Obviously anything designed to be used in the bone dry, warm, calm and sunny conditions of Britain would fall apart as soon as it saw a raindrop

 

[FLYBOYJ]

Yes ...... but having the potential to do and doing something are not the same thing. Many things can absorb moisture and most can be treated to prevent it.

If it has potential to absorb moisture it will, and that's why aircraft (especially wood aircraft) are so heavily inspected.

I'm not suggesting that there might not be some problems of degradation specific to wood or wood composites, just as there are those specific to metal structures (heaven knows how many gallons of zinc chromate were applied to US aircraft of the period). I just haven't seen any evidence that moisture absorption was a problem for the materials used in the de Havilland Mosquito.

I haven't seen anything specific on it either, but it is usually a problem, as is corrosion on metal planes as you so stated.