Aircraft Wood, again...;-)

[kolibri282]

Wood, the time honoured material for aircraft, has its place also in the 21st century, or so I think. That, to me, was once again confirmed when I read that the tail fins, both horizontal and vertical, of the English Electric Canberra had been built of wood (including the skin) as is stated in an answer to the article below:
Canberra
This is confirmed if you look at older cut away pictures of the aircraft. The Canberra was one of the fastest aircraft of its time and allowed NATO for quite a while to safely fly above the Soviet Union for photo reconnaissance.

As a bonus you can download a really nice picture of a DeHavilland FoxMoth if you right click on the background picture of the article which is visible to the sides of the text. The picture appears several times down the article but you can download only the one at the top, where you also see the Canberra in the middle of the page.

Currently I am waiting for the laser cutter in the GarageLab, a club of DIY enthusiasts which I joined a year ago, to be operational again after we moved to other facilities. I will then have the ribs of a wooden wing for my monocopter model cut out. It will take some time though, before I can fly it as the control of such beasts seems to be quite tricky, from what I have seen so far.

Take care everyone and fly safe!

Jürgen

 

[WaspAir]

My brother's Air Force service included maintaining electronics on the Martin RB57F, the double-span winged (122 ft) U.S. recon derivative of the Canberra.

 

[okikuma]

Various combinations of epoxies are hazardous to humans. Wood, the first and foremost composite material, is not so hazardous. Working with wood can be labor intensive, however many enjoy the time and effort to create a wonderful final product.

Jurgen, you and I are not alone in the value of wood as a material for aerospace usage. Japan just released the LignoSat. A small wooden satellite to test the durability of wood in the vacuum of space.

Wayne

World's 1st wooden satellite arrives at ISS for key orbital test

LignoSat could help change the way we build satellites.

www.space.com

 

[Doug Riley]

Wood got a bad rap from, among other incidents, the death of Knute Rockne, football star, in the crash of a wood-winged airliner. There reportedly was rot in the wing spars.

Wood is food for rot-causing fungi. These organisms need moisture to live, so keeping the wood dry is key to the long life of this natural composite.

I'm rebuilding a wooden sailboat built in the 1950's with NO sealer on any of the wood hidden from view. This cost-saving strategy did not work out well. Seal those wooden parts!

 

[Aerofoam]

Wood got a bad rap from, among other incidents, the death of Knute Rockne, football star, in the crash of a wood-winged airliner. There reportedly was rot in the wing spars.

Wood is food for rot-causing fungi. These organisms need moisture to live, so keeping the wood dry is key to the long life of this natural composite.

I'm rebuilding a wooden sailboat built in the 1950's with NO sealer on any of the wood hidden from view. This cost-saving strategy did not work out well. Seal those wooden parts!

I did a lot of boat building in the PNW.
A trick the wooden boat guys use for rot is anti freeze. if you only have a small amount of rot and don't want to replace the entire board which may be 2 layers deep in the framework. You can mix anti freeze 50/50 and soak the rot. it kills everything and actually penetrates the cell walls of the cellulose structures. The rot will not progress unless the area is exposed to moisture enough to leach out the anti freeze, but hopefully you fixed that problem before dealing with the rot. You can also do this as prevention for those blind areas you don't want to deal with again...
Some people also ad borax to the mix....
If it is structural, there are some epoxies that are as thin as lacquer thinner that will penetrate then plasticize the rot......

 

[kolibri282]

@Wasp: The NASA RB-57 is quite a beast and it is impressive, that this air frame is still useful in the 21th century after so many years of service.
@Waine: Epoxy is hazardous but I wonder about aerodux glue, which, I think, was the stuff Ken Wallis used for his rotor blades (I had sent a post about it some time ago). Aerodux had been invented long before Epoxy and I seem to remember that it is based on very different primary materials.
Using wood for a satellite is surprising but an interesting idea, I will closely watch how this will work out. At least you don't have a moisture problem up there....;-)

@Doug: There seems to bee a bit more to the story regarding the longevity of wood, as there are wooden churches in Norway which are over a thousand years old and Norway is not a desert. On the other hand Mosquitos and Hornets seem to have had significant issues in tropical environments.
Regarding the Fokker accident I heard though, that blaming it on the use of wood was rather a business move by other plane manufacturers to promote aluminum planes, but yes, wood can deteriorate. That is the reason why Ken Wallis, as far as I know, used Hydulignum, a sort of ultra processed wood, for his rotor blades. The propellers of the Halifax bomber and several Spitfire variants were made of that stuff and Britain is not known for having an exceedingly dry climate...;-)







@Aerofoam: quite interesting way of avoiding rot, thanks for the hint!

 

[StanFoster]

I have a natural bias towards anything made out of wood. My career of building stairways out of wood allowed me to buy gyros and a Helicycle made out of aluminum.

 

[XXavier]

Those who work with wood are usually nice people... Jesus of Nazareth is the prime example.
But those who work with metals are often seen as dirty and harsh men, who dwell in 'dark satanic mills'...

 

[kolibri282]

Beautiful quip, XXavier..

 

[Doug Riley]

My lady friend refers to my aircraft construction activities as "cutting up stupid metal." No love for poor old 6061-T6 and 4130...

 

[kolibri282]

Try using wood, Doug, that might change her opinion....
I must admit though, that my wife also considers my work on rotorcraft a pure waste of time....;-)

 

[Doug Riley]

I've switched to mostly working on wooden boats! I haven't yet heard a reference to "cutting up stupid trees," but I suppose it's just a matter of time.

 

[Mayfield]

I would be interested in some spitballing by Mark, Doug, Juergen and others that may be interested.

Basic idea:

To build an open frame gyro using wood as the main structural element. Think Bensen, Dominator, GyroTechnic, etc. made primarily of wood. I know there have been a couple of box frame gyros made of wood and a couple of enclosed gyros constructed with wood as a major element. I'm curious about other ways to do it.

If the idea generates scratch pad sketches followed up by some folks with engineering chops making calculations, it could be a fun exercise.

Parameters:

Uses readily available wood.
Uses home workshop type tooling such as saws, planers, sanders, clamps.
Uses room temperature adhesives.
Laminations are permitted.
Attachments and fittings can be made from commercially available extrusions or shapes that can be fabricated without a mill or lathe or that a local machine shop can fabricate at a reasonable (???) price.

Not to be considered:

Whether it can be built better, cheaper, faster, lighter, stronger using other materials.

Jim

 

[Aerofoam]

I would be interested in some spitballing by Mark, Doug, Juergen and others that may be interested.

Basic idea:

To build an open frame gyro using wood as the main structural elements. Think Bensen, Dominator, GyroTechnic, etc. made primarily of wood. I know there have been a couple of box frame gyros made of wood and a couple of enclosed gyros constructed with wood as a major element. I'm curious about other ways to do it.

Parameters:

Uses readily available wood.
Uses home workshop type tooling such as saws, planers, sanders, clamps.
Uses room temperature adhesives.
Laminations are permitted.
Attachments and fittings can be made from commercially available extrusions or shapes that can be fabricated without a mill or lathe or that a local machine shop can fabricate at a reasonable (???) price.

Not to be considered:

Whether it can be built better, cheaper, faster, stronger using other materials.

I think a wooden frame open gyro would be fairly simple, especially with oriented pressed laminations like an archery bow., or a box beam construction. it would be better with composites, but not necessary.
The entire center frame could be a single section with the suspension bolted on.

The down side is longevity, exposure and maintenance. Wood doesn't weather well....

What would be really interesting is to build one out of wood, bamboo, lashings and forgings, all pre industrial revolution techniques......

 

[Mayfield]

I think a wooden frame open gyro would be fairly simple, especially with oriented pressed laminations like an archery bow., or a box beam construction. it would be better with composites, but not necessary.
The entire center frame could be a single section with the suspension bolted on.

The down side is longevity, exposure and maintenance. Wood doesn't weather well....

What would be really interesting is to build one out of wood, bamboo, lashings and forgings, all pre industrial revolution techniques......

Thanks Mark,

I had not thought of bamboo, but it has some good structural qualities.

Could the landing gear be manufactured as a laminated bow? I would guess that bundled bamboo could be used as a gear leg, but a laminated bow would be gorgeous. In either case, rebound would be dealt with by wheel scrub as it is on other spring gear.

It would be neat if a few of the folks here would brainstorm it a little and get to the point of sketches, drawings, basic material selection, Fabrication techniques, even building up some simple test articles. Sort of a crowd sourcing project.

Jim

 

[Chook]

Thanks Mark,

I had not thought of bamboo, but it has some good structural qualities.

Could the landing gear be manufactured as a laminated bow? I would guess that bundled bamboo could be used as a gear leg, but a laminated bow would be gorgeous. In either case, rebound would be dealt with by wheel scrub as it is on other spring gear.

It would be neat if a few of the folks here would brainstorm it a little and get to the point of sketches, drawings, basic material selection, Fabrication techniques, even building up some simple test articles. Sort of a crowd sourcing project.

Jim

Jim, some time ago, one of our members was toying with the idea of using a CNC router table to cut out a single laminated section which included the keel, mast and instrument pod supports. He is an ideas guy and in never proceeded past that. He was also going to incorporate strain gauges at various locations in the build to keep an eye on the stress and critical points.
Now that should put the cat amongst the pigeons on this forum.

Regards....Chook.

 

[Mayfield]

Thanks Chook,

I understand that if the idea had commercial advantages it would have been done by now.
. However, is it feasible? I don't know but some of the engineers hanging out here will know what would be required.

Jim

 

[Aerofoam]

Thanks Chook,

I understand that if the idea had commercial advantages it would have been done by now.
. However, is it feasible? I don't know but some of the engineers hanging out here will know what would be required.

Jim

I think is is feasible, but not a permanent enough medium. It would quickly break down if left in the sun in Az. or the wet of the PNW.........

 

[raghu]

I would be interested in some spitballing by Mark, Doug, Juergen and others that may be interested.

Basic idea:

To build an open frame gyro using wood as the main structural element. Think Bensen, Dominator, GyroTechnic, etc. made primarily of wood. I know there have been a couple of box frame gyros made of wood and a couple of enclosed gyros constructed with wood as a major element. I'm curious about other ways to do it.

If the idea generates scratch pad sketches followed up by some folks with engineering chops making calculations, it could be a fun exercise.


Jim

Funny you bring that up Jim. The first and only time I met the late Chuck B. (and the much alive Doug R.) at BD in the early 2000's, CB mentioned he had drawn up (as an exercise) a gyro frame based on 2 by 4s . As a wood fan that certainly stuck in my mind and I have often pondered the viability.

Not withstanding crashworthiness and few other important things it certainly has some merit to it. Here is a cursory look at bending strength that in general will be the most critical. Let us compare a glued lamination of two 2 by 4s (nominal 3" x 3.5") with a square 2" 1/8" 6061 t6 tube. The laminated 2 by 4 has a section modulus that is ~10 times higher than the standard square 2' 1/8" tube. In other words to be equal in bending strength to 6061 tube, the lumber would need a bending strength of 4 KSI. This is certainly in the range of the higher grade 2 by 4s. Aircraft grade would be significantly stronger (a little over 2 times).

Also, the laminated 2 by 4 would be ~ 2 times as stiff as the 2" 6061 tube. However the laminated frame would be twice as heavy than the standard 6061 tube, more in line with a steel tube gyro frame. Designed around aircraft quality wood, the wood frame would be about the same weight and a little stronger than the 6061 frames in common use. All this is just a quick and dirty calculation, and obviously there is more to it than just bending strength and no one should go out and build it.

 

[kolibri282]

A few years ago a wooden C-30 replica has been built in Spain, it has been discussed in the forum here:
C-30 wood 1
the plans are here:
C-30 plans
The well known Pietenpol Aircamper is built in wood but I once saw a welded tube design for the aircraft. I calculated a comparison between the two and the welded tube design was slightly lighter, some 10% or so, as far as I remember.

One very interesting part would of course be the rotor. With a wooden design one could incorporate things like tapered plan form and positive twist. Sounds like a fun project, so I am looking forward to see what comes of it.