How much faster is an aircraft with wooden surface?

[spicmart]

How much is the speed loss of a plane with riveted metal surface compared to the same plane with wooden surface?
Taken the Mosquito for example, how much slower would it be as a metal plane?

 

[Crimea_River]

No easy answer but, just to clarify, the Mosquito had no "wooden surface". Rather, all surfaces that were wood were covered with doped fabric and several layers of paint.

 

[pbehn]

The Mosquito was an advanced design made of wood, but the emphasis should be on the design not that it was made of wood. I had a clean design, no defensive armament, a two man crew and low cooling drag. The key, in my opinion, is designing a bomber on fighter performance principles, as soon as you stick a defensive gun on you need a gunner, space for a gunner and his un and ammunition, oxygen, line of sight and room to move etc. With regard to your OP tere were studies done with split peas and rivet heads on Spitfires to establish where flush rivets had to be used and where they could get away with domed rivets, since flush rivets are harder and slower to do it was a performance versus production issue.

 

[spicmart]

No easy answer but, just to clarify, the Mosquito had no "wooden surface". Rather, all surfaces that were wood were covered with doped fabric and several layers of paint.

So, no rivets which tangle with the airflow?
That's what I meant.

 

[Shortround6]

A lot depends on the actual workmanship of the aircraft. A lot of Soviet wooded aircraft had poor fit and finish. A lot of metal aircraft had poor fit and finish from many nations, some look like assembly was done by drunken ship fitters.

Another question is how long was each aircraft out of the shop/factory. This may tend to swap back and forth. A number of metal aircraft tended to dish or oilcan between attachment points/supports. But this doesn't show up for while. The metal aircraft finish (surface smoothness) may deteriorate as it ages but it may sort of hold it's own for a while before really going bad. Wood or wood/fabric may be better for a few months (?) but then have a more rapid decline if not well cared for.

A good wood aircraft may be very close to a very good metal aircraft like the P-51. But the P-51 was better built ( joints, rivets, sealant/sanding) than many other WW II aircraft.

 

[Thumpalumpacus]

A lot depends on the actual workmanship of the aircraft. A lot of Soviet wooded aircraft had poor fit and finish. A lot of metal aircraft had poor fit and finish from many nations, some look like assembly was done by drunken ship fitters.

Another question is how long was each aircraft out of the shop/factory. This may tend to swap back and forth. A number of metal aircraft tended to dish or oilcan between attachment points/supports. But this doesn't show up for while. The metal aircraft finish (surface smoothness) may deteriorate as it ages but it may sort of hold it's own for a while before really going bad. Wood or wood/fabric may be better for a few months (?) but then have a more rapid decline if not well cared for.

A good wood aircraft may be very close to a very good metal aircraft like the P-51. But the P-51 was better built ( joints, rivets, sealant/sanding) than many other WW II aircraft.

Metal is more resistant for being less absorptive, but like wood it is vulnerable. Wood expands and contracts with both temperature and humidity. Metal doesn't expand or contract as much with humidity (because it's not as absorptive), but still swells and shrinks with temp. Both will suffer from temperature extremes (say, 75°F at ground level vs -40°F at 30,000 ft). The change in altitude and therefore humidity will affect the wooden aircraft more (because colder air is drier) but the temp will cause expansion and contraction in both airframes.

Not sure it matters enough over three years,, unless you're flying in Southeast Asia.

 

[GregP]

A lot depends on the actual workmanship of the aircraft. A lot of Soviet wooded aircraft had poor fit and finish. A lot of metal aircraft had poor fit and finish from many nations, some look like assembly was done by drunken ship fitters.

Another question is how long was each aircraft out of the shop/factory. This may tend to swap back and forth. A number of metal aircraft tended to dish or oilcan between attachment points/supports. But this doesn't show up for while. The metal aircraft finish (surface smoothness) may deteriorate as it ages but it may sort of hold it's own for a while before really going bad. Wood or wood/fabric may be better for a few months (?) but then have a more rapid decline if not well cared for.

A good wood aircraft may be very close to a very good metal aircraft like the P-51. But the P-51 was better built ( joints, rivets, sealant/sanding) than many other WW II aircraft.

As an 18-year volunteer at a flying museum, mostly WWII aircraft, I have seen a LOT of warbirds. Our museum flies more than 20 on a regular basis.

I have never seen one that looked like it was assembled by drunken shipfitters. The workmanship of the U.S., British, Japanese, Soviet, Swiss, and German warbirds I have seen is universally pretty good. Flush riveting is more time-consuming than non-flush riveting, but you really only need a wing flush-riveted to about the first 1/3 of the chord, after which the universal head rivets don't seem to affect speed at all.

Of course, some fighters were so clean that they needed mostly flush rivets. A P-51D comes to mind. Can't think of a non-flush rivet on it, but I also haven't really looked for one. Mind you, it STILL has a fabric rudder!

Look at a Mooney, the fastest normally-aspirated piston civil light aircraft. The wing is only flush riveted to about 1/3 chord.

 

[MIflyer]

The F6Fwas not flush riveted. The outer wings of the F4U are fabric covered over an aluminum structure, which is the approach used on the Ercoupe as well. But the ailerons of the F4U are wood with fabric covering while the ailerons of the Ercoupe are all aluminum with flush riveting. The performance differece between the Ercoupe and the F4U is about 300 mph, so obviously speed had less than a dominating effect on surface finish.

The T-28 uses aerodynamic surfaces that look like they were based on the Mustang but are not flush riveted; speed was not important but strength and cost were.

 

[Shortround6]

I have never seen one that looked like it was assembled by drunken shipfitters.

Wing panels are over lapping. I am not counting the head rest panel fairing.
Here is a walkaround photo gallery of a Bristol Blenheim.

Bristol Blenheim Walkaround Gallery

 

[tyrodtom]

I'm an autobody repairman, been doing it just a little over 50 years.
About every aircraft I been able to look at close in person has appalling fit and finish, compared with a car.

Ripples around rivets, if you look down the sides under the right light the ripples in the panels are easily seen.
What we in the trade would describe as "friendly fenders", they wave back at you.
But I realize they've got much thinner panels, and they have to be flexible.
If you tried to get them perfect, they'd never stay that way long, they have to flex.

But from the description I read about how they prepared the Mustang's wings sounds a little like what I do in bodywork. They primed the wings, thick coats, and sanded it smooth.

And there's a few close pictures on the web I've seen of the sides of world record speed attempt aircraft, like the late 30's Spitfire, and Bf-109, and racing aircraft .
You can tell the whole fuselage has been smoothed and massaged, by filling the low spots and blocking it smooth.

Their sides look nothing like the usual aircraft from the factory.