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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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 Posted Thursday, November 12, 2009 @ 11:21 PM
I am sure you knew this was coming... covering the fuselage… I have asked several member of my soaring club who are somewhat experts with glass to give me a hand covering the RF-4’s fuselage. I have read over all the threads and references in the forum.. printed them out and gave them to my friends. One guy builds boats (world class around the world sail boats) using fiberglass over wood, the other friend has built fiberglass aircraft and gliders. The glider builder is really concerned with weight so I tend to think he may have some good ideas. Here are a few of his:
1. Lay up the curved surfaces first, using a roller to press the West System Resin into the 1.5 oz. fiberglass cloth… get it to completely adhere to the wood then remove excess resin with a dry roller (he says it may not look good at first but the key is get it flat with good contact then sand the edges down where it meets the straight/ flat surfaces so the seams are overlapping the joints and not visible… lay up the flat surfaces and then come over it again with resin and filler—micro beads)… sand, finish, etc.
In removing the cotton fabric, it would appear that the cotton fabric made the bend over the wood structures, i.e., over the front bulkhead (under the metal fire wall), into the cockpit areas, under the fuselage (where the fuselage sits above the wings) and around the tail mounts, etc.
So here are probably the first of a number of questions:
1. Where do you start with the fiberglass fabric and in what order do you cover the fuselage with fiberglass? Do you bend the fiberglass over the 90 degree bends or use fiberglass tape? Do you put the fiberglass everywhere there was cotton fabric? What technique do you use to get a good job with minimum weight, resin, and filler?
2. I have removed all the hardware like the canopy hinges and tail mounts, etc. so I can fiberglass under the hardware… but, do you fiberglass over the screw holes or cover them with tape (or something) so they can be used after the covering is in place?? Any tricks to save time later??
3. What are the steps and products I should use to fill low area or should I just accept that it is a wood aircraft with wood imperfections? (like on the turtle back where the wood sheets join)
4. Do you use heaver glass fabric, or carbon fiber, or Kevlar in any critical areas?? Like where there is going to be wear getting in and out of the aircraft??
I have read the West System recommendations. I have used SuperFil- a Poly Fiber product (very light weight epoxy filler) on some dents, gouges, imperfections, etc., ...it works great and sands out nicely. Once dry MEK has no effect on it. The West System also recommends roughing up the surface with 80 grit sandpaper.
Please give me your recommendations... I value all of them...
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Sam M.
First Sergeant
Gender: Male
Location: Santa Paula, CA
Registered: Jul 2008
Status: Offline
Posts: 228
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Posted Friday, November 13, 2009 @ 02:08 AM
I dont understand the fiberglass process, in another 30 or 40 or even 60 years is the next guy who wants to recover this going to have a heck of a time getting the glued on fiberglass off the wood with out damaging it?
[Edit by Sam M. on Friday, November 13, 2009 @ 02:19 AM]
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Sam M.
First Sergeant
Gender: Male
Location: Santa Paula, CA
Registered: Jul 2008
Status: Offline
Posts: 228
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Posted Friday, November 13, 2009 @ 02:12 AM
we coated the bare wood with Non-tautening Nitrate dope. It takes five or six spray coats to get a nice glossy base. Fabric (lightweight) is applied with a thinned version of the Non-tautening Nitrate. It is complicated to explain all the nuances of covering, but basically the fabric is taken off the roll, tacked along the edges, lightly ironed to remove wrinkles and then rubbed into the base nitrate with a thinned coat along the entire wood surface. It is extremely important to get a good bond to the wood with no air bubbles. We finished the fabric with Butyrate Dope colors. If you want specific information, you can call me. 805-525-7081. Good luck. Rowena
[Edit by Sam M. on Friday, November 13, 2009 @ 02:13 AM]
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jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
Registered: Mar 2007
Status: Offline
Posts: 583
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Posted Friday, November 13, 2009 @ 11:25 AM
Its my impression is that the fiberglass will never come off the wood without damage to the wood or extensive sanding right through the glass layer.
That being the case, I would hope that the fiberglass will never crack like the fabric did and any refinish job will be to remove the
paint down to the glass only.
Pretty much the last recover you will ever need to do.
I'd say that even a thin layer of glass will protect the wood in the high wear areas and you'll only need to repaint those high wear areas now and then as the paint condition will tell you when.
I like the glass idea, but keeping the weight down is the biggest concern, for both the glass fabric and especially the application of epoxy resin.
If your new at it, you want a long cure epoxy so you have extra time to work the resin properly into the weave and roll out the excess resin to keep it light as possible.
--------------------
Ray
RF4D #4057 N-1771 Rectimo 1400cc
http://picasaweb.google.com/jb92563/FournierRF4D
http://www.touringmotorgliders.org
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philippe
Private
Gender: Male
Location: France south alps near GAP
Registered: Feb 2009
Status: Offline
Posts: 8
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Posted Friday, November 13, 2009 @ 04:37 PM
I just want to give you my experience in lay up fiberglass with epoxy.
first well choose fiberglass fabric. the fabrics woven are not similar. some fiberglass fabric accept curve surface and other don't. i think than the best choice is a "sergé" woven 80/100 grs/m2 to lay up your fuselage.
second is to choose a best epoxy system very liquid (like water). some epoxy system used for gloss surf board are a good choice because they have thixotropic and good wet specifications. (you can well wet the fiberglass)
mixing the epoxy: for the quantities: the same weight of fiberglass=the same weight in epoxy. not more 500 Grs in one time. if not you will have problem with chemical reaction in epoxy who will be very hot.
put epoxy with brush on wood, after fiberglass, and again epoxy, but not too much.
the best is to remove the excess of epoxy with a card (like visa card or similar).
after cured sand a little and put on all the surface a mix of epoxy/microballoon very thin enough for to not see the fiberglass frame. after sand the entire surface.
you can paint it.
for the screws holes : don't be worry about it, you will can see them throught the fiberglass:epoxy cured by transparence.
begin on a little surface like vertical fin.
excuse my bad english.
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dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
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Posted Friday, November 13, 2009 @ 05:01 PM
My not-so-great experience putting fiberglass on the vertical stabilizer last month has given me pause in the process. The surface came out quite lumpy. I think the resin was too thick (too cold) and I tried to cover both sides at once. In trying to fill and smooth the lumps, I sanded through some the fiberglass. Even if the surface was smooth, it will still require sanding and filling at the seam areas -- with the danger of sanding througn the glass. I'm sure Eugenio has gotten this process down with all the planes he has done, but I was suprised at the bad experience I had with it -- and I've made a lot of things out of fiberglass.
I would definately experiment on the vertical or horizontal stabilizer first before comitting to the fuselage.
I'm also looking at the fabric option again. It seems easier and more fool-proof since there is no sanding of the fabric once it is down.
--------------------
Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
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Jorgen
Captain
Gender: Male
Location: Lund, Sweden
Registered: Apr 2007
Status: Offline
Posts: 834
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Posted Friday, November 13, 2009 @ 07:05 PM
Salut Philippe,
n'est t'inquitéte pas! The universal language at this site is Fourniench and the word misconception is not in that dictionary 
Good topic, good discussion. My experience with Epoxy resin (SP-system, UK brand with very practical pump dispenser for dosage of base and hardener) is limited to a couple of surfboards (windsurfing Sam, the waves here would make you laugh) and could be summed up with messy, but acceptable result in the end. Just like Rowena I´m not sure whether the advantages of a tougher inner skin outweighs the messiness, and I wonder if weight penalty might be a factor. I've also used epoxy resin and fibreglass to stiffen the wooden runnerplank on the iceboat with good result, so I suspect you will get a mild but perhaps noticeable "stressed skin"-type of stiffening effect.
On the other hand, the argument that it's easier to restore a dope/fabric wood surface sounds a little bit like Brittish plumbing: " -Why do you put the plumbing on the outside of the houses? The pipes will freeze and break!" " -Yes, but the pipes are easier to fix when they are outside the walls...."
May the 4's be with you/ Jörgen
[Edit by Jorgen on Friday, November 13, 2009 @ 07:09 PM]
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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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Posted Tuesday, November 17, 2009 @ 06:59 PM
Progress is good and I am starting to get my fiberglass crew together along with supplies... I will have pictures and information in a few weeks. West Systems technical experts have been very helpful and I hope it will go well, but as always, it is a learning experience.
Some people have asked about the reason I want to use fiberglass rather than a Dacron fabric like the Poly Fiber system that I plan to use on the wings... and it gets down to having the fabric move and crack. Somewhere down the line, it would appear that fabric glued tight on the large wood surface areas of the fuselage... just like the original cotton, will show cracks. One of our glider club members has a Schiebe which is constructed somewhat like the RF-4..... it is being recovered AGAIN this winter because the fabric cracked and delaminated from the wood. It only made a few flights before it went back to the shop. I will have to get some pictures... this was a professional fabric job and the paint (dark blue) was great. I don't know exactly why the fabric pulled off at several locations.. at first we thought it might have something to do with the heat of the aircraft (again the dark color absorbing heat), or the finish on the wood.
Another reason is the advice of forum members, esp. those that rebuild these types of aircraft for a living.
Everyone seems to have their reasons for one product/process over another... we'll just have to see how it goes.
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dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
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Posted Tuesday, November 17, 2009 @ 10:10 PM
I'd still recommend you go through the whole process on the vertical stabilizer before you tackle the big job.
--------------------
Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
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Sam M.
First Sergeant
Gender: Male
Location: Santa Paula, CA
Registered: Jul 2008
Status: Offline
Posts: 228
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Posted Tuesday, November 17, 2009 @ 10:26 PM
Wood expands and contracts extensively with moisture. If you cover the wood with fiberglass the fiberglass will not expand and contract causing damage to either the glass or the wood which ever decides to break first. I would never cover a wood airplane with fiberglass. I have been covering airplanes for twenty years and have had excellent results using the original method of dope and fabric. Dope will last a good thirty years, and if finished with the butyrate process is easily repairable. If someone had cracking after three flights they did not properly apply the dope and fabric. It is, as they say, an art. Please do not destroy a rare airplane by putting glass over the wood. It breaks my heart to think anyone would do such a thing. Rowena Mason
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Jorgen
Captain
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Location: Lund, Sweden
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Posted Wednesday, November 18, 2009 @ 02:21 AM
Eugenio,
per piecere, it would be interesting to hear your views. Again, good discussion- the original method against using "modern" materials, pros and cons.
May the 4´s be with you/ Jörgen
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JamesB
First Sergeant
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Location: Near Seattle, WA; USA
Registered: Oct 2006
Status: Offline
Posts: 257
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Posted Wednesday, November 18, 2009 @ 11:46 AM
The fiberglass coating seems like a good idea.
One thing I find interesting. It was fairly common in older wooden boats to have owners cover wooden hulls with fiberglass. In practice, these would look good for a few years, then over time, many would delaminate.
The solution came through using monel staples to attach the fiberglass cloth to the hull. Some would wet the hull first with epoxy, lay on the cloth, staple it, then do a final wetting. Others stapled the cloth to the hull, then wet it in place. Regardless of the sequence, the staples created a mechanical attachment of the cloth to the hull to work in concert with the chemical adhesion of the epoxy. I have not heard of delamination in boats where there was good surface preparation and a combination of mechanical & chemical adhesion.
Granted, one would expect a boat hull to be exposed to more moisture and move more than a fuselage. But the principle and concerns are the same. Despite all the care you take in surface preparation and epoxy temperature/mixing/etc., is there any way to help assure that the material adheres to the wood? (to help counter delamination caused by the natural movement of the wood through flying or moisture).
Eugenio made the point of using thin cloth. I would guess that the thinner the layer, the lighter it is and the more it can flex with the wood.
The veneer/plywood on the fuselage is too thin for staples. Yet, I wonder if there is a way to mechanically attach the cloth to work in concert with the epoxy?
[Edit by JamesB on Wednesday, November 18, 2009 @ 11:47 AM]
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Dan Rihn
Private First Class
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Location: Southern California
Registered: Mar 2009
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Posts: 18
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Posted Wednesday, November 18, 2009 @ 12:17 PM
We have had excellent luck covering the wood wings on aerobatic aircraft with Fiberglass.
We use very light "Deck Cloth" and WEST systems Epoxy. Done right it will be as smooth as a fiberglass sailplane.
WEST Systems is very easy to use.
Dan Rihn
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jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
Registered: Mar 2007
Status: Offline
Posts: 583
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Posted Wednesday, November 18, 2009 @ 04:05 PM
I'm also going to have to do this fuselage recover next year and so am keenly interested in how this goes.
I don't think there is any way to prevent a wood aircraft from expanding and shrinking according to the moisture content of the wood.
With that in mind it would intuitively seem that a less elastic material like cured fiberglass is less likely to expand and crontract with the wood
so somehing has to give, either the bond to the wood or the fiberglass?
Epoxy however does have a powerfull grip and perhaps can prevent movement of the surface layer of wood...so with the ply bonds fail instead?
I have demolished an old glass covered wood boat and thats what I observed, the glass took the 1st layer of ply off with it and the ply bond failed instead.
I would think that what is needed is a flexible material and paint system that can accomodate the repeated expansion/contraction cycles.
I have only ever used Polyfiber and can't say which system is the most likely to follow the wood and stay attached, but am very interested in hearing what people experiences have been.
I think that proper application is absolutely essential to get good results thought in any system.
Heat buildup is also a problem in keeping the material attached so a light color would probably survive longer.
--------------------
Ray
RF4D #4057 N-1771 Rectimo 1400cc
http://picasaweb.google.com/jb92563/FournierRF4D
http://www.touringmotorgliders.org
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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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Posted Wednesday, November 18, 2009 @ 11:08 PM
Greetings:
As I am getting my fiberglass crew together (with a number of emails going back and forth) there was of course a concern for safety, esp. if I allowed glider club members to attend the covering process as a master class in glass. A number of pilots with glass ships what to learn more about fiberglass. Anyway, the subject of epoxy sensitivity came up.... kind of like poison ivy/oak, and we wanted to make sure we were doing it right. Steve Rander owns Schooner Creek boat works and is one of my glass experts (you can Google his web site to see his shop and projects)... most of this was new to me (even after reading about the subject in West Systems, so I thought you might find some of his comments enlightening. Here is Steve's response to a question about epoxy exposure:
Certainly epoxy exposure can be a problem but it is not what every one thinks. I and my crew have between 20-30 years each of nearly continuous exposure and none of my workers or I have become sensitized. I have had people come to work for me that were already sensitized and I had a guy that I used to sell epoxy to that became sensitized but he was building a big catamaran and was living in it while he was building it on an everyday basses 24/7 for over two-three years.
Now what’s my secret? First keep it off your skin and if you do get it on your fingers, arms etc. don’t use acetone to take it off (ya I know you have to from time to time) use one of the waterless hand cleaners like SBS-30 or the little towels you get in the tub at the auto supply (they work great). Second if doing a big lay-up provide ventilation. Third if a pot starts to kick off set it out side to do its thing. Fourth and this one is really important, don’t sand the stuff until it is completely cured and then be sure and wear a GOOD dust mask. All just simple logic and involves a little respect for what you are using.
There are a couple other reasons that some people have a worse time. First the brand of epoxy being used (West is a little easier on us humans then some others) and secondly the person them selves, it turns out that fair haired, light skin people have to be more careful then others so if you have to stay out of the sun and protect your skin and always seem to have chest colds and skin allergies stay away from all epoxies. Once you are sensitized you have walked into a whole world of other problems because you will find that you are sensitized to many other things besides epoxy.
As the boy scouts say.... "Be Prepared." I will keep you posted as we progress.
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Jorgen
Captain
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Location: Lund, Sweden
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Posts: 834
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Posted Thursday, November 19, 2009 @ 12:44 PM
Bob,
with all due respect to you and your buddy, in my opinion Epoxy resin needs to be treated even more cautiously than that- it IS toxic stuff! A dust mask is inadequate to protect against the vapours from Epoxy during curing, you need a gas mask with an active filter, the ones with 2-300 hour "TBO". Protection during sanding is of course important, I´d use the filter mask there as well. DON´T remove the gloves to "just feel" the sanded glass- you will get millions of small glass spears coated with resin in your fingers (ask me how I know this....) Also, you need to protect your skin during application/curing with gloves, not only remove the resin after the job.
It is a matter of the level of protection; light or fair skin means thinner skin- easier for the Epoxy to penetrate into the blood stream. IF enough Epoxy entered your system to sensitize you is hard to know, Epoxy allergy does not manifest itself only when exposed to Epoxy. I became allergic to my cat after building my first surfboard and once you have screwed up your immune system to go to DEFCON 8 because of various irrelevant stimuli, you can´t unscrew it. Epoxy Resin is a marvelous material once in place, but it IS "messy", so be careful out there.
May the 4´s be with you/ Jörgen
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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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Posted Thursday, November 19, 2009 @ 01:07 PM
Jorgen:
I should have labeled this thread, "preparing to cover with fiberglass".... my crew is very SERIOUS about safety and that is one of the reasons I bring this to everyone's attention... I thought it should me explored. In addition to epoxy we must respect all the other materials and components, like MEK, paint remover, oil, dust, etc. It has been raining here in Oregon for the past week (yes we do get lots of rain) and I have not been able to wheel my fuselage outside to do more work. Much of what I do is done outside for these very reasons. In the old days, many of us didn't think much of changing the oil and getting engine oil on our hands, but times and knowledge have changed. We have all learned that it is smarter to prevent a problem, i.e., Be Prepared includes, be informed, be safe!
Thanks for your contribution... great information.
I will start a new thread on actually covering N7725.
Cheers,
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eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posted Thursday, November 19, 2009 @ 02:48 PM
I think that epoxy, like all chemical products, must be handled carefully, but I also think that each person is differently sensitive to it. I personally use epoxy, polyester, polyurethane and all sorts of chemicals without any particular precaution, but I know of people that just smelling epoxy's fumes get ill. (I started using all these sorts of chemical 35 years ago with model building).
Eugenio
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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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Posted Sunday, November 29, 2009 @ 00:08 AM
OK... today was the day to fiberglass... it took about 6-7 hrs. once everything was positioned... lots more fiberglass cloth than I thought since there is a major waste of fabric to get it to lay right... we were not concerned with saving fabric but to get an excellent job. I am VERY pleased with the results. Having two friends who are experts in glass was wonderful. There are so many neat techniques that you see when they are working... hopefully you will get some of that in the image album I made for the forum. Collin was a big help... safe to say we both learned a lot. Steve is one of the top boat builders using wood and fiberglass.. so when he showed up something it was really worthwhile. There was also the timing and temp.... letting things set up to the right stage.
Here are the images... hope you find them interesting/helpful. The process worked well for us.
http://picasaweb.google.com/lh/sredir?uname=Bomar1&target=ALBUM&id=5409367749295204833&authkey=Gv1sRgCI-ag5DBvKm_rgE&feat=email
By the way... there was no problems with vapors, in fact we hardly knew we were working with epoxy unless we were using the heat guns. All the safety items, esp.the gloves worked fine.
Cheers,
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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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Posted Sunday, November 29, 2009 @ 00:19 AM
sorry for a few spelling errors, e.g., years rather than yards in one image, etc.... made the corrections and then saved the first copy.... it has been a long day...
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eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
Registered: Oct 2006
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Posts: 294
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Posted Sunday, November 29, 2009 @ 04:19 AM
You are a perfectionist! Neat job. And, at last, it will weight the same than using Ceconite or Poly-fiber or similar products but will last much more.
Use the same process on the wing D-box and all plywood covered parts. I suggest also to remove all fittings, bellcrank etc. to inspect them. Check also aileron hinges and bellcrank supports in the wings and change all rusted hardware. If you need metric bolts I can send you some, they are standard DIN bolts, but they're not so easy to find in hardware stores (also here). Remember to torque all bolts/nuts before covering the wings or you will have to cut away some cloth to tighten loose fittings (it happened to me with the aileron hinges).
Eugenio
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jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
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Posted Monday, November 30, 2009 @ 12:16 PM
Wow, nice job.
By my estimation that finish weighs only about 5 lbs?
That really did not seem like a difficult task, all the work is in the preperation before the glass.
Really appreciate the pictures documenting the process.
How long do you have before the epoxy cures hard?
I'll have to give that process some serious consideration as I am facing the same task within the next year.
I was wondering if it is possible to buy colored epoxy (White) to provide a good base for any other color you might add and
perhaps only require the finish color coat?
What kind of color paints can you apply on Epoxy?
I am seriously considering HIPEC covering on mine as the wings already have that material applied and it seems to hold up extremely well
with a gloss finish, even on the part of the wing you stand on to enter the cockpit.
I think I will recover the Rudder with it to try out the process in the next few months.
--------------------
Ray
RF4D #4057 N-1771 Rectimo 1400cc
http://picasaweb.google.com/jb92563/FournierRF4D
http://www.touringmotorgliders.org
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eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posts: 294
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Posted Tuesday, December 1, 2009 @ 02:52 PM
Epoxy can be coloured, but I do not think it is worth. In any case you must sand the whole surface and use a primer before laying the final coat. You will be using the same primer (plasticized, obviously) on fabric covered parts to have a good surface for the final coat of paint.
Epoxy is quite hard to sand so you will use a coarser sandpaper and with the primer you will cover all scratches, then with a fine one you will finish the surface easily because the primer is much softer.
Eugenio
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Bob Grimstead
Captain
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Posted Monday, January 4, 2010 @ 11:29 PM
Hi Guys,
I haven't jumped on to this thread before because I have not personally re-covered a Fournier fuselage.
However, I've owned one for six years and another for two years, and I am cautious about using fibreglass as a fuselage covering.
Here I must say first that I do have huge respect and admiration for Eugenio's knowledge of Fourniers and their maintenance, and I feel awkward about questioning his obvious expertise. But I am just a little uneasy about the fibreglass covering.
The original fabric and paint covering does not last for much more than twenty years, but it does have the advantage of being flexible with the airframe.
My concern is that fibreglass resin is very hard and stiff, while Finnish Birch plywood is wonderfully flexible and resillient. I agree with Ray's concerns above. Might it not be possible that, as the ply twists and flexes, the rigid fibrglass and resin will adhere extremely well to the outer veneer of the plywood? Something has to fail, so might it not be that the glue bonding the inner plywood veneers together might fail before anything else, leaving you with a very hard and inflexible but extremely thin outer structure over useless inner plies?
Since Ray says that is what happened with his boat, I am inclined to think the same thing might happen with a Fournier over time?
My concern is for our long-term safety as well as for the airframes' longevity.
Just a thought.
Yours, Bob
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eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posted Wednesday, January 6, 2010 @ 03:09 PM
Originally the fuselage was covered with cotton, and this material adheres quite well to the wood, that's why it lasted 20+ years (if you haven't left your RF under the water too much). Synthetic materials are much more flexible and have worste adhesion properties, this is why I prefere fiberglass. I can understand the concerns of Sam and other people used to use well known processes used on lots of US produced planes. I personally started with models, ans ever since I was used to use fiberglass to cover wood structures. I also have enough experience on glass fibre gliders, and I personally never had problems neither with wood nor with fiberglass. Who say that fiberglass with epoxy is not elastic, probably never saw a high performance glider whose wings flect like an arch without breaking.
Surely dacron or other synthetic fabrics are easier to use, quicker and less dangerous, but this is another thing.
And for Bob's concern about fire, fiberglass don't burns.
Eugenio
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Bob Grimstead
Captain
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Posted Wednesday, January 6, 2010 @ 11:04 PM
Thank you Eugenio,
I did say that I did not know for sure, and of course, when you mention it, yes, fibreglass wings do bend at least as much as wooden ones, so probably fibreglass is the correct, flexible covering for a plywood fuselage.
As always, Eugenio has the right answers, and I apologise for doubting him.
Yours, Bob
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SteveBeaver
General
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Posted Thursday, January 7, 2010 @ 00:00 AM 
Perhaps some people confuse the rather brittle and flammable polyester resin fiberglass with the newer, more flexible epoxies such as West Systems - the brand favored for aircraft use. There is a huge difference between the two types of resin.
Steve
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jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
Registered: Mar 2007
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Posts: 583
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Posted Thursday, January 7, 2010 @ 11:17 AM
Now that you mention it, the boat delaminations were with the Polyester resin system.
Forgive my hundreds of questions but I am not familiar with the West Epoxy/glass system.
Another question about the Epoxy/Glass is its UV resistance.
What sort of UV blocking paint do you put on top to protect the Epoxy, or is it already resistant to UV degradation?
Perhaps the opaque color top coat is all the protection needed?
What kind of top coat paint? Epoxy paint?
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Ray
RF4D #4057 N-1771 Rectimo 1400cc
http://picasaweb.google.com/jb92563/FournierRF4D
http://www.touringmotorgliders.org
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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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Posted Thursday, January 7, 2010 @ 01:34 PM
After we finished the fiberglass process, my boat building friend called me and said, "you have a crack or rip in the plywood." I could not believe it... I had been over every inch of the plywood many times, and if there had been damage, I would have seen it... but he was right. The clear West System resin really made the defect visible. OK, is was a very small crack, a few of my aviation friends said it was not even worth repairing, but how to be sure there was no damage under the plywood? Steve had me grind out the area to solid undamaged material, then using layers of heavier fiberglass cloth, make the repair. It was very easy to do and I believe it is another reason for doing the job with fiberglass. I have never worked with fiberglass before, but following directions completely and weighting out the mix is really no problem. Steve gave me the materials to make some fiberglass fill material (super light wt. glass beads, silica and fiber materials) for the bead joints between the gas fill and fuselage. I will get pictures of that process, but here are two of the small crack... probably caused by a hard landing. Again, it was a simple repair.
http://picasaweb.google.com/lh/sredir?uname=Bomar1&target=PHOTO&id=5424046595440789970&aid=5424046583236888817&authkey=Gv1sRgCKrDrpqbyvH6wQE&feat=email
Robert
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SteveBeaver
General
Gender: Male
Location: Columbus, Ohio - USA
Registered: Jan 2007
Status: Offline
Posts: 454
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Posted Thursday, January 7, 2010 @ 06:42 PM
West Systems is the epoxy recommended for finishing the all-wood Sequoia Falco. I posted a link to the page on their website with all the details. It is good stuff. Not only does it remain flexible but somewhat surprisingly, is is very sandable. Tends not to clog the sandpaper too much. But it through Aircraft Spruce.
http://www.seqair.com/skunkworks/Painting/Notes/Notes.html
Steve
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