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Glass/Foam VS. Aluminum


John PA

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I love the concept of glass/foam construction. But it is my understanding that it does not have the longevity of aluminum and you must hangar a glass aircraft to avoid sun and heat damage.

 

I'm sure this is an age old argument. But I am trying to decide between the two. A friend of mine building a Sonex offered me some pretty convincing arguments in favor of a metal aircraft. Some thoughts please? Thanks!

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A glass airplane properly protected with the right kind of paint will last a real long time. I think you may be reading a lot of posts from owners (such as myself) who would not even think of leaving their glass baby outside. Just give me an aluminum aircraft----and you will hear me talk about not even thinking of leaving my aluminum baby outside.

 

There are those that think that the money saved from parking outside will be enough for a new paintjob five or so years down the line----ok---whatever.

 

While I am away from home----and a large storm blows thru---I am never worried (its in the hangar). When a hail storm comes---no worries. Theft and vandalism---you got to get thru the hangar first.

 

And most important of all----where are you going to work on your airplane? Afterall, you are in experimental aviation---you will work on your plane. If you are rich enough to have someone else deal with your plane---then you are rich enough to have a hangar anyway. Most airports won't let you work outside. And, if you were outside---it is either too hot in the summer, too cold in the winter, too windy whenever...

 

I don't buy the argument between glass and aluminum for storage outside. I do buy the argument;however, about having a preference of working with one over the other.

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Your friend is spouting a very one-sided argument. Fiberglassed airplanes are resistant to fatigue, whereas metal airplanes begin fatigue from Day 1. A fiberglass airplane will outlast a metal airplane, but none of us fly that long to really find out.

 

No airplane should be stored outside for all the reasons Drew mentioned.

Wayne Hicks

Cozy IV Plans #678

http://www.ez.org/pages/waynehicks

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I love the concept of glass/foam construction. But it is my understanding that it does not have the longevity of aluminum and you must hangar a glass aircraft to avoid sun and heat damage.

 

I'm sure this is an age old argument. But I am trying to decide between the two. A friend of mine building a Sonex offered me some pretty convincing arguments in favor of a metal aircraft. Some thoughts please? Thanks!

Talk to someone who has built a plastic plane and they will give you just as many arguments in favour of glass & foam. (There's a reason Burt Rutan chose this method over 30 years ago and it continues to gain popularity.)

Although I have not done any metal work to compare, I have done some glass/foam construction so far, and really anjoy working with the materials.

Based on everything I've read, as long as you give it a UV protective coating, and paint it a light colour, there is no problem. I think that if hangaring these things was an absolute requirement and/or if they were known to deteriorate faster than all-metal planes, they wouldn't have become nearly as popular as they are.

On the certified side, the number of plastic planes seems to be increasing all the time.

 

Joe Polenek

Joe

Cozy Mk IV #1550

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Your friend reminds me of the people at my EAA chapter when I introduced myself and said that I was building a Rutan canard. One of the fellows said matter-of-factly, "You're going to have delamination problems."

 

I think that much of this "knowledge" originates from second hand stories of composite aircraft built from the 1970s, when slightly different foams, materials, and builder know-how existed. For example, the original VariEze (and Long-EZ I believe) used a foam for the fuselage that would compress and crumble under pressure. As a result, there would be a hollow cavity where the foam was (delamination).

 

In the 3+ decades that these homebuilt canards have existed, you can have confidence that the basic issues have been worked out. They're great planes, if that's what you want. There are reasons for choosing types like a Sonex, but I love my composites.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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The first plane that flew around the world without a refill was a Rutan design made of glass.

A Rutan design was the first private venture to make it into space. Material used ...... composite.

How many of the new military design are using composite?

 

What is the glide ratio of a Sonex compared to any number of composite aircraft offered today.

 

My neighbor 2 doors down started his aluminum plane at the same time I started my composite. I have a fuselage and am finishing my canard as we speak. He is getting pretty close to having a left wing.

T Mann - Loooong-EZ/20B Infinity R/G Chpts 18

Velocity/RG N951TM

Mann's Airplane Factory

We add rocket's to everything!

4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

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My neighbor 2 doors down started his aluminum plane at the same time I started my composite. I have a fuselage and am finishing my canard as we speak. He is getting pretty close to having a left wing.

 

That's not a fair comparison, TMann. YOU do a 60+ hour chapter in 3 hours. :D :D :D

 

Joe Polenek

Joe

Cozy Mk IV #1550

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That's not a fair comparison, TMann.

:( ..... sorry.

Point being, a new design is produced/prototyped by Scaled Composites on an average of about 1 per year. It is without a doubt a 'mecca' of aircraft enginuity.

 

If what you want to build is a standard look aircraft then the aluminum/rivit should work well for you. I think it's kind of a cool look. I'd like to build a wood and fabric super cub after I finish with this one.

 

As far as what drove my choice of a Long-EZ, it centered around ease of construction, stall characteristics, ease of flight, low parasitic drag and top-end speeds.

T Mann - Loooong-EZ/20B Infinity R/G Chpts 18

Velocity/RG N951TM

Mann's Airplane Factory

We add rocket's to everything!

4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

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Thank you all for your responses. Some very good arguments.

 

Jon

I am curious about the changes in in glass construction techniques since the 70's. It sounds like we can now build better glass airplanes. Is there anywhere I can read up on these changes? Did a google search with little success.

 

Another argument I've heard in favor of metal is that with a glass design, you loose your resale value as compared to metal. I guess buyers shy away from glass.

 

At this point, in order to sway me away from glass, I will need to hear from a former glass builder who says "been there, done that. It was a bad idea."

 

I am still on the fence here. I need to do some reading. Any articles or studies that I can be pointed to would be very helpful.

 

Thanks!

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A local guy was building a Long-Eze around 10 years ago, and he got finished with quite a bit of the build. I think he may have had the spar mounted to the fuselage. Anyway, he quit, and cut up all his work because of these stories of composite airplanes lasting around 10 years before they fall apart. At least thats the local story.... and I here it when I tell people what I'm building.

 

Composite airplanes do last a long time. If you choose the composite route, John PA, you'll have some aluminum and wood guys raise their eyebrows and not approve. They won't understand composites and threrefore you'll here it from time to time. The few local builders here are me, a metal guy, and a wood guy. We all think each process and plane is very cool, and we support each other.

Andrew Anunson

I work underground and I play in the sky... no problem

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Another argument I've heard in favor of metal is that with a glass design, you loose your resale value as compared to metal. I guess buyers shy away from glass.

It seems that incomplete glass airplanes (not flying, in any state) have low resale value, sometimes barely fetching the value of the raw materials. Flying Long-Ezes and Cozies and nicer Variezes seem to sell for alot of money! $50k to $100k is not uncommon for a nice Cozy. Flying Velocities seem to sell for Big Money. Finished RV's may be easier to sell... I don't know. I am not building my Cozy to sell it. I am building to fly it, and sell it when I'm too old to see, hear, and walk.

 

At this point, in order to sway me away from glass, I will need to hear from a former glass builder who says "been there, done that. It was a bad idea."

Its going to be hard to find that anywhere on the net, because most people who do something they regret don't stay involved with that part of their life. Is Dave Clifford building an RV 10 now (and his Cozy also)?

 

The sonex is a cool little plane, and it seems to be a fast build airplane too. Composite airplanes aren't the quickest airplanes to build, but many such as Tmann show its all up to the builder.

 

The long history of Rutan derivative airplanes is enough for me to know that composite construction is good for me. I haven't read any books are studies other than what on the net (which can be biased).

Andrew Anunson

I work underground and I play in the sky... no problem

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I think I can offer some perspective on the original question. I've owned a Beech Musketeer for coming up on two years now, and have been involved in a forum specific to the "Aero Club" planes as they're known in the Beech community. We originally wanted to build an RV9A and ordered and built most of the tail kit. As I got closer to my license, we realized we wanted to FLY instead of build and try to rent, as the rental fleet here is slim.

 

In over two years of being a forum member there, there have been not one, but SEVERAL issues with members having major corrosion issues on their birds. These are not planes that are prone to it, it just happened to specific airframes. Keep in mind that the fleet ranges in age from 44 to 24 years of age. We've had a few members that had to scrap their airframes after finding corrosion that was just too expensive to fix.

 

The reason I'm telling you this is because metal corrodes. It's not a question of if it will try to corrode, but when it will try to corrode. There are all sorts of precations to take to KEEP it from corroding. These include the cladding on the metal, alodining, painting, zinc chromate prep, etc. The bottom line is, you have to initially prepare metal and then KEEP ON TOP OF IT through continued maintenance. Re-paint, re-prep, treat with corrosion inhibiting sprays, etc. Hangaring a metal plane is one of the best things you can do for it.

 

The members that have had corrosion problems have things in common. The one that stands out the most is that they or the previous owner tied the planes down.

 

Replacing metal airframe parts on a certified aircraft can get REAL expensive. Replacing metal components on an experimental is a LOT less expensive if you can do it yourself. Replacing components or portions of a composite airframe is basically time and the cost of materials.

 

On a certified aircraft you can quickly exceed the value of the plane. Not as much of a problem with experimental metal planes unless the manufacturer is no longer around and you can't produce the part yourself. Really not much of an issue with a composite as you just MAKE the part or repair it.

 

I've studied this stuff at length for several years and we've finally decided to build a Cozy. Just trying to find the right project currently. Going to go take a look at one in October and we'll go from there! Went and helped out on another member's project last weekend, and had a great time. I still need a ride though, so if anyone within a 500 mile radius of Boise ID wants to offer, We'd love to fly over when the weather is good for a ride! Hey, it's another excuse to go flying and we're always looking for those...

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Jon

I am curious about the changes in in glass construction techniques since the 70's. It sounds like we can now build better glass airplanes.

 

Does anyone have info on the foam changes made since the early varieze that Jon mentioned earlier. I'm interested to know how this has improved sine the early days.

The original VariEze and early Long-EZ plans called for a foam for the fuselage sides that would crumble very easily, leaving obvious delaminations on parts of the fuselage that came in contact with knees, elbows, etc. That's since been addressed as part of the Canard Pusher newsletters.

 

That is just one example to point out how the build process as a whole has matured over the years. Others are more adventurous and will use different foams, or cover the top of the strakes in carbon fiber (another place where there's a lot of "foot traffic").

 

Ultimately, the moldless composite build process IS very much the same. It works well.

 

Also, I don't think anyone has mentioned the video where Burt Rutan and Mike Melvill first jump on an aluminum wing and it crumbles like tin foil. They then stand and jump on a canard wing -- the tiny one -- and it just flexes and bounces right back without so much as a single ding. Convinced me right there.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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I'm just about done with my Cozy MKIV #656 and have sold that and am also building an RV-10. As in any construction method, you need to follow the recommended and proven proceedures. The RV-10 is being primed as I build with Zinc Phosphate, not Zinc Chromate primer. the difference being is that the Phosphate is a "self etching" primer that etches and really digs in to the aluminum and hardens over a period of several days. It is EXTREEMLY durable compared to the Chromate primer.

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Another couple of data points for your consideration.

 

The most popular high performance plane sold today is the Cirrus: Glass/foam

 

others of its ilk are those sold by Lancair, diamond, virtually all gliders, and of course Boeing with their new baby. The military uses extensive composites in their aircraft.

 

Don't overlook the boating industry, which is almost all composite.

 

Oh, and did I mention, Cessna, a metal aircraft industry leader wants to acquire Colombia (the certified lancair) another glass aircraft.

 

"If you really want Class, you build with GLASS :P ."

I Canardly contain myself!

Rich :D

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...loose your resale value as compared to metal. I guess buyers shy away from glass...

People buy what they are familar with. The RV is popular because it looks like a plane and it use material people see on GA aircraft more regularly.

 

If you look at Velos or Cozys, no one is giving them away. A lot that goes into the sale price of an aircraft is not just the popularity of the design, but the condition of the project and what condition the engine is in. If the engine is about run out, it is going to go for a song since it won't be long that you will be paying for a rebuild.

 

If you go to Rough River, you will be amazed how much things have advanced on these aircraft. What you find on later aircraft is that the finishing techniques are much better today than on the older birds. Another thing that was interesting was look Zeitlin's Cozy that had a prop failure earlier this year take off parts of the trailing edge of his wing and part of his winglet. Its all fixed now. That would have been very hard to do with metal...

Nathan Gifford

Tickfaw, LA USA

Cozy Mk IV Plans Set 1330

Better still --> Now at CH 9

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It really sounds like there are just a lot of valid arguments for all types of construction. They all have their strengths and weaknesses. I have been reading extensively on the net about types of foam PVC, polyurethane, polystyrene, and different glasses and epoxies. I'm fairly decided that I want to try my hand at a composite plane. In honesty, I really hate aluminum construction. I've been helping on a friends Sonex. It's just not me. Too confined. Too rigid. Glass is more "open" or "free".

 

Now on to deciding what airplane to build.

 

Thanks everyone for your input. You have been very helpful.

 

John

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In honesty, I really hate aluminum construction.

I tried not to say that myself, but I feel the same way. I don't know why.

 

Glass is more "open" or "free".

Right! Take a look at your car's dash, doors, and center console. I look at these things now and say, "I could build that."

 

Now on to deciding what airplane to build.

A canard of course! :) If you need a traditional layout (and have some immediate $), this kit looks nice: www.flyallegro.com (but just build an Open-EZ)

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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One other consideration to take into account is allergic reaction to the epoxy. Early on at the start of the build 8 years ago, I read somewhere that its not a matter of IF you become allergic to epoxy,,,,it's WHEN. Well for the last year or so I have noticed I was having allergic reactions on days I was using epoxy, skin blotches of red, itching, sneezing, small bleeding sores from itching. Yesterday was really bad for me. I had to do a good size layup on my back modifying the cowling to fit the airfilter box. I got epoxy on my arms, head, hands,,,,,,it was ugly and I made a mess trying to do it alone. I'm still feeling the effects this morning. I suffer from allergies in general so I am thankful I made it this far with only minor reactions at the end. Some people suffer really bad side effects and actually have to give up their project. Note that I am not the best to use as an example as even though I used the nitrile gloves, I still managed to get epoxy on my skin and clothes no matter how carefull I was.:scared:

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Dave's right about allergies. Do all you can to minimize exposure and be careful about solvents that can carry epoxy through your skin.

There is a another reason to stay away from MEK. Not only are the fumes extreemely hazardous to your health to breath in, solvents are obsorbed through the skin! Ever read the warning label on a can of MEK? BAD STUFF!! I used a 50/50 mix of denatured alcohol/laquer thinner. Still hazardous but not as bad as the MEK and it cuts the epoxy really good.
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