Let's talk about wood...

killbilly

Vocals, Lyrics, Triangle, Washboard, Kittens
The pics of that Bellanca in the Iola thread got me thinking and doing some research, and I was surprised to find out that the Viking had wooden wings, as do many older airplanes.

I started wondering about wooden airplanes. I know wood has been used for decades to build em', and I know there are quite a few airplanes still flying that have wooden wings and fuselages.

My question is thus: how long, really, is a wooden airplane good for? Assuming it's taken care of (and I don't know what that entails) is it actually better in some respects?

I know there are some Citabrias and Decathlons out there which are metal-winged and apparently more desirable (judging by price points) so it started me wondering about deficiencies on wood.

Basically, I'm looking for a primer of sorts on wood-winged airplanes. Because if I ever bought an airplane (a goal of mine) I'd really like to consider one.

(I know this is a deep question, but I figured it might spawn some lively conversation, too)
 

killbilly

Vocals, Lyrics, Triangle, Washboard, Kittens
Spent 100's of hours in a Super Viking. Wood rocks... 300hp helps
Tell me more...

I mean, everything I've read about the Super Viking says that it's a wonderful airplane...but I didn't want to make this a referendum on that airplane. More of an exploration of wooden airplanes.

Now, I'm assuming that the construction contributes to the Viking being a wonderful airplane, but in what way? Why is this? Seems like some of the most popular airplanes out there are wood. What about wood makes a great airplane?
 

jynxyjoe

Queso King
Oh, I'm not an engineer man. The wood wing x-fers the load very well across the whole wing. You are subject to wing rot unfortunately and dummies stepping foot on the wrong part of the wing thus tearing through it (fabric). The gun tube/ski tube was fun in the superviking as was the outstanding performance. You can't get the thing overweight or out of CG unless you fill the airplane with lead bricks. The vikings are all so different depending on the year made. Some years they were like "hey lets put a ski tube in! on some of the planes", then it was "Hey lets throw the aux tank behind the pax seat and see what that does", then "hey lets just throw it back on the outside of the wing but lets keep the old fuel selector and toss on ANOTHER one in series with it just for the aux" then "hey do you think this needs cowl flaps?- nah! do we still have a ski tube?", followed by "throw some cowl flaps on there". It is the '69 corvette of it's day. Never mind all the retractable gear door cover crap you have to go through.

The plane is a great toy for the rich and I've been very satisfied with the overall quality of it. Although at times I wonder if they Rolls Royce engineers were the ones that secretly made the plans for it.

If you can find it, there is a Viking nut named "Cliff Allen" who wrote an article about the plane that was spot on. For the life of me I can't find it online for you. He's a guy in western mass whose probably got close to 1000 hours in different ones. Great dude to talk to.
 

Blip16

Well-Known Member
i have flown a few Champs from the 40's, they have wooden wings, no issues! i think they need to be rebuilt every x thousand hours, or at least inspected pretty thoroughly
 

Blackhawk

Well-Known Member
There is a Beech Stagerwing currently udergoing a restoration here. Original wood. Not sure of the year, but they stopped making them in 1949, so it's at least 60 years old. 99% of the original wood is still good. They are replacing some that is still good (such as on the wings), as part of the restoration.
Decathlons do/did have some problems with the wood spars in aerobatics. What is scary is that some spars that have passed inspections were later found to have major cracks.
 

RICHARD5

Well-Known Member
I've owned two wood planes. And I will still consider owning a wood plane. In the Stinson, the bottom wing skin was fabric-covered plywood from leading edge to trailing edge and full span.

Certain species of wood have a higher strength to weight ratio than steel. It should not be thought of that the use of wood was because it is a lesser technology and now we are so advanced compared to back then. The main reason wood is not used is because of tooling and production methods favor metal and because wood is more labor intensive. But with current CNC, the use of wood (or wood laminates) is not ineffective WRT material and labor costs.

The big concern with wood is it needs to be protected from excessive moisture content and it needs adequate airflow to aid this. Those "drain holes" in the covering MUST be kept free and unobstructed. In EVERY case of wood rot in the planes I have inspected, the holes were obstructed. Quite often it was plain to see how the rot propagated in that rib bay due to a closed drain hole.

They aren't just drain holes, they also allow for air circulation. In the hotter climes, it is possible for the wood frame to get too hot...this is a rare instance but it is possible. This would result in checking (if the moisture content gets too low).

All in all I would say wood doesn't require more maintenence than, say aluminum. It's just different (duh) therefore has different requirements.
 

ctab5060X

Well-Known Member
The big concern with wood is it needs to be protected from excessive moisture content and it needs adequate airflow to aid this. Those "drain holes" in the covering MUST be kept free and unobstructed. In EVERY case of wood rot in the planes I have inspected, the holes were obstructed. Quite often it was plain to see how the rot propagated in that rib bay due to a closed drain hole.

They aren't just drain holes, they also allow for air circulation. In the hotter climes, it is possible for the wood frame to get too hot...this is a rare instance but it is possible. This would result in checking (if the moisture content gets too low).
A VERY BIG :yeahthat:!

That is probably the biggest area of concern with airplanes that have any wood material used at all.

I own a 1968 Champion Citabria with the original wood spars. It was rebuilt about 8 years ago and the wood spars were in excellent, repeat excellent condition considering the life the airplane had prior to the rebuild project. In short the plane was a heavily used primary trainer and also used to teach basic aerobatics for over 25 years.


I know there are some Citabrias and Decathlons out there which are metal-winged and apparently more desirable (judging by price points) so it started me wondering about deficiencies on wood.
American Champion should be ashamed of themselves for trying to make money off of the wood wing airplanes. Just because the new Citabrias and Decathlons were manufactured with metal spars...grrr. The value of the wood spar airplanes took a major hit, and they have yet to really come back to what they were in relation to metal spar airplanes.

To make a long story short, ACA came out and said that wood spar equipped Citabrias and Decathlons were dangerous and that every airplane should have the wings rebuilt with factory provided metal spars (at a hefty price, I might add). This was the factorys answer to the discovery of several wood spar aircraft that had cracks found in the spars (later found out they were groundlooped or otherwise damaged, but the damage was not reported). I was even told by someone at the factory that we were crazy for staying with the wood spars, saying that they were dangerous and ACA recommended metal spars. ACA really alienated a lot of the owners of the older airplanes when they did this.
 

Velocipede

New Member
Well, I don't know much about airplanes made of wood, but I can tell you this...In AI school at NPGS they did a demo for us. They took various kinds of material and put it in a calibrated press to see which one took more pressure. They used steel, aluminum and wood.

Wood was by far the strongest material.

And if you want an example of what wood can take in aviation, look no further than the British Mosquito bomber.
 

killbilly

Vocals, Lyrics, Triangle, Washboard, Kittens
Interesting stuff. So, I know moisture is a big deal on that...

And for what it's worth, my DPE for my PPL is a Citabria owner. I think she's got wood spars in that airplane.

When you have a wood airplane with fabric covered wings, or whatever else they use (plastic? I dunno) how long does the covering last? What do you have to do to protect it? I imagine that UV would hurt it over time, but I've seen ads for wood-fabric airplanes that say, "wings recovered 10 years ago." Is 10 years a long time? What do you have to worry about there?
 

RICHARD5

Well-Known Member
When you have a wood airplane with fabric covered wings, or whatever else they use (plastic? I dunno) how long does the covering last? What do you have to do to protect it? I imagine that UV would hurt it over time, but I've seen ads for wood-fabric airplanes that say, "wings recovered 10 years ago." Is 10 years a long time? What do you have to worry about there?
Those are good questions. More in-depth answers can be found in internet searches. Use corrosion, aircraft coverings, protective finishes, as key words.

Moisture is a problem for every material. After all, water is a solvent.

WRT fabric, the duration of useful life is largely determined by periodic and regular maintenance. In fact, that statement is true for, say paint over aluminum.

So, "Is 10 years a long time?" It depends, it's relative to the level of care and upkeep. With regular washings, timely repairs when required, etc, 10 yrs is not a long time. Semi-abandoned, left to rot, etc, then even 1 yr is a long time. Proper upkeep of fabric or wood is not more labor intensive than, say painted alum.

UV exposure is a problem for everything from avionics, interiors, paints, and fabric. It's a harsh world we live in.

The last covering I did was Stewart Bros. Water soluable, non-toxic. Just about idiot proof.
 

RICHARD5

Well-Known Member
To address your earlier question about metalized wings, I think the higher asking price is because most pilots are more familiar/comfortable with metal because they've drunk the Kool-Aid (biased against wood).

Metalizing does reduce the useful load and may create problems for the structure underneath the skin. Therefore, I think the appeal of metalizing is emotion-based.
 

Polar742

All the responsibility none of the authority
Billy,

If you have the means, get a hangar, buy a Champ and have fun.

I'm waiting for the confluence of time and money myself....:drool:
 

ctab5060X

Well-Known Member
When you have a wood airplane with fabric covered wings, or whatever else they use (plastic? I dunno) how long does the covering last?
I depends on the covering, whether it is ceconite, poly-fiber, or Grade A cotton. It also depends on the composition of the covering as well, i.e. all poly, all Grade A cotton, or a mixture of ceconite and cotton.

My Citabria (always hangared) was 30+ years old when it was recovered. Not from the condition of the fabric, but other reasons. When the airplane was manufactured, it was covered in ceconite with cotton reinforcing tape (the fabric that goes over screws and rivets). The ceconite itself was still very much serviceable, and overall in really good condition. However, the cotton tape had seen much better days and was cracking and tearing, causing areas of the dope covering to peel up and peel away from the ceconite.

What do you have to do to protect it?
Hangars are best, but some type of shelter to proctect the covering from the elements.

I imagine that UV would hurt it over time, but I've seen ads for wood-fabric airplanes that say, "wings recovered 10 years ago." Is 10 years a long time? What do you have to worry about there?
Yes and no. UV does hurt pretty bad, especially when dealing with the older cotton and dope covered airplanes. However, in recent years, the technology behind the poly-fiber material and the paints used for them have made the UV harm less than it used to be. I have seen Cubs that were completely recovered 10+ years earlier, stored outside in the sun, and looked excellent.
 

t-cart

Active Member
A lot of the super duper aerobatic planes have wood spars and ribs in them. That says a lot right there. Sean D Tucker and until his death, Jim Leroy put on some of the most g pulling civilian airshows out there.
 

ctab5060X

Well-Known Member
Billy,

If you have the means, get a hangar, buy a Champ and have fun.

I'm waiting for the confluence of time and money myself....:drool:
Champs are fun airplanes, but like anything else, require a good prebuy from a mechanic that knows the type. Most of the original Champs (not this overpriced new LSA thing) were covered completely in cotton, not ceconite. Hopefully by now, most of the originals still out there have been recovered with a more durable material.

Champs are fun airplanes to fly around in. Slow, you can fly it with the door off, most of the older ones (7AC, 7BCM, 7CCM) had no electrical system (handpropping). Very basic airplane. But, as much as I like a Champ, I love my Citabria!
 

ctab5060X

Well-Known Member
A lot of the super duper aerobatic planes have wood spars and ribs in them. That says a lot right there. Sean D Tucker and until his death, Jim Leroy put on some of the most g pulling civilian airshows out there.
When ACA (American Champion Aircraft) started to really push their metal spars, the argument went something like this... what happens when you bend spruce slightly and what happens when you bend aluminum?


Personally, with my spars being in great condition, it isn't worth the $19,000 to buy aluminum spars. And that doesn't include the cost and downtime to completely recover the wings.
 
R

Roger, Roger

Guest
Another reason that I think wooden aircraft have fallen out of favor is that there are a lot fewer mechanics around who really know how to work on them. I know that in my A&P training we had only very minimal training in working with wood airplanes. I would guess that unless you are based somewhere where there are a lot of wooden airplanes flying around, a mechanic who knows what he's doing with a wood airplane might be pretty hard to come by.
 

ppragman

FLIPY FLAPS!
Wood is awesome, you don't see it much anymore, I think in part because of longevity issues with the product (see Roger, Roger's post). Its had to keep it in good shape for extended periods of time. Wood is a composite material however, and will hold up to stress just like other composites will, in fact better, because nature has been perfecting wood over millions of years, and we haven't had the same timescales to practice with the cirrus/diamond/longeazy/other goofy looking plastic airplanes here/etc. People don't like to ride on airplanes that are made out of wood however, and I doubt that it would be adviseable to tell them that they are riding around in an airplane whose wing stays on because of a wooden spar, that being said, wood rocks the ####.
 
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