Couple o' questions..

I'm in the process of "gearing up" to build a plane with 4130 space frame and wood wing. I've bought a reasonable mitre saw for the wood, and abrasive cutoff wheel for the tubing. Since then, I've found a 77 tooth carbide tipped blade that will fit the saw,, says it's only for mild steel. Any body know why this could be a problem with 4130 tubing .035 - .049 wall thickness?

As to the wood wing, anybody know where/how to buy Aerolite? It's for sale all over the UK, and none of the stores there will ship it to the US for some reason. Canada, maybe?

TIA

bk

4130 is a hard steel and will dull that blade pretty quickly. The abrasive cutoff wheel in the saw will work well to cut steel, although it's noisy and throws a lot of sparks.

Since you will likely need to cut out a lot of flat stock as well as tubing, I recommend a metal cutting band saw. It cuts tubing and thicker angle as a horizontal saw but can also be used as a vertical saw for cutting flat stock for fittings, gussets and the like. Harbor Freight has an inexpensive model that I've had for years and has held up well. Buy a couple of spare blades when you buy the saw, as a fuselage project will go through several.

http://www.harborfreight.com/horizon...saw-93762.html

Can't help with the Aerolite, but I wonder why you want to use it? There are plenty of other commonly available glues for wood construction.

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Originally Posted by briankk

I'm in the process of "gearing up" to build a plane with 4130 space frame and wood wing. I've bought a reasonable mitre saw for the wood, and abrasive cutoff wheel for the tubing. Since then, I've found a 77 tooth carbide tipped blade that will fit the saw,, says it's only for mild steel. Any body know why this could be a problem with 4130 tubing .035 - .049 wall thickness?As to the wood wing, anybody know where/how to buy Aerolite? It's for sale all over the UK, and none of the stores there will ship it to the US for some reason. Canada, maybe?TIAbk

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Ditto on the above post on the saw suggestion. The little bandsaws with a good bi-metal blade will be your best friend. As for the aerolite, if you are talking about the acid cat type I would avoid it. Instead might I suggest a plastic resin type adhesive such as DAP weldwood plastic resin. It has all the good traits of the acid cat type aerolite, but none of the issues. It has much better creep resistance than epoxy as well.

Bandsaw and belt sanders both on my list. Probably need a router too, and maybe a table for it.

Trying to think incrementally, I don't have room to build the fuse here and now, but wings I could do. Naturally, I'm well equipped to build the fuse I have no room for, but lack a lot of woodshop equipment I need for the wings I have room for, unless, of course I set up a wood shop to build them.

Got the Weldwood on the shelf here now, wanted to do some comparison bits with Aerolite to see which I prefer, and start building ribs. I'm told that the Falco is done with Aerolite, but that they have to import the stuff in bulk to buy it at all. Perhaps I should go talk to those guys and see how they do it. I don't understand how such a common component could become rare and difficult to get, but there it is..

bk

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Originally Posted by briankk

Bandsaw and belt sanders both on my list. Probably need a router too, and maybe a table for it.Trying to think incrementally, I don't have room to build the fuse here and now, but wings I could do. Naturally, I'm well equipped to build the fuse I have no room for, but lack a lot of woodshop equipment I need for the wings I have room for, unless, of course I set up a wood shop to build them.Got the Weldwood on the shelf here now, wanted to do some comparison bits with Aerolite to see which I prefer, and start building ribs. I'm told that the Falco is done with Aerolite, but that they have to import the stuff in bulk to buy it at all. Perhaps I should go talk to those guys and see how they do it. I don't understand how such a common component could become rare and difficult to get, but there it is..bk

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The acid cat aerolite type adhesive was/is popular for plywood sandwich type construction due to the long open time needed for that type of construction. Unfortunately it also has had issues with longevity under some conditions that lead it being banned in Australia. Note that the "weldwood" type was not banned and is still approved for certified aircraft in australlia. If you are doing a standard type "open" construction I think you will find the weldwood type just as nice if not nicer to use since you dont need the long open time, and there is only one component to deal with.

For an adhesive I would recommend T-88 epoxy, probably the most popular adhesive for homebuilts.
Here is my Harbor Frieght band saw set up for vertical sawing
http://eaaforums.org/attachment.php?...tid=4449&stc=1

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Originally Posted by amv8vol

For an adhesive I would recommend T-88 epoxy, probably the most popular adhesive for homebuilts.
Here is my Harbor Frieght band saw set up for vertical sawing
http://eaaforums.org/attachment.php?...tid=4449&stc=1

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Unfortunately popularity is not always a good indicator of performance. In some cases yes, and in some cases its a me-too attitude that builds something's popularity. When you look at the "great glue debate" with an objective mindset, it becomes very clear that there is really one big tradeoff. Simply put if you group the room temperature resin glues (weldwood) and resorcinol together, and compare them to an epoxy, what you are trading off is performance for the need of precision joinery. You will never exceed the mechanical and thermal properties of a properly done resorcinol joint with any readily available material, period. Theres hard data for that so its not a debate. Epoxys are less fussy about joint fitment and are good for gaps. Is that a good thing? Im not sure as I hope it does not permit sloppy work. Unfortunately epoxys don't like heat, and even creep at room temperatures ( ever notice wind turbine blades that have taken a permanent bow due to the force against them?). So there you have it, trading easier joinery for adhesive performance. Don't get me wrong, I use both West and T-88, but I know their limitations, and I know its not the best performing structural adhesive.

Ah. The "glue wars". I won't bother you with the extensive research I've done online about this, but the upshot is that I won't be having any epoxy in my plane.

I have a little Tab book by a woman named Ruth Spencer, spent 20-30 years building, restoring and repairing wooden aircraft, never used anything but Weldwood, never had a failed joint..

The Mosquito bomber, built with Aerolite, was used widely for several decades there after with no documentable complaints I could find until the guy in OZ started on about it.

I've concluded that a lot of the "information" concerning the problems with the Urea glues is likely FUD from epoxy blenders, and though I've no evidence of that, I'm aware of enough problems with epoxy to avoid it if I have a choice..

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Originally Posted by briankk

Ah. The "glue wars". I won't bother you with the extensive research I've done online about this, but the upshot is that I won't be having any epoxy in my plane. I have a little Tab book by a woman named Ruth Spencer, spent 20-30 years building, restoring and repairing wooden aircraft, never used anything but Weldwood, never had a failed joint..The Mosquito bomber, built with Aerolite, was used widely for several decades there after with no documentable complaints I could find until the guy in OZ started on about it.I've concluded that a lot of the "information" concerning the problems with the Urea glues is likely FUD from epoxy blenders, and though I've no evidence of that, I'm aware of enough problems with epoxy to avoid it if I have a choice..

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Glad to hear it. :)Fads come and go. Usually they come into popularity when they are "new and exciting", then time proves them good or not, determining their future. The Australlian CAA banned all UF glues, then later reversed that decision a few years later as the failures were all with one manufacturer with one type of UF glue in the 1940's plus their own testing. Unfortunately the same fellow that got Australlia to ban all UF glues, got the FAA to listen to him as well. Hopefully with some pressure the "weldwood" type adhesives will be put back in 43.13 following Australlias lead. In all honesty I dont know why T-88 is still around in homebuilding. The lap sheer is no better than modern PVA glues, its bond to woods like oak just stinks and it cant handle heat. Oh well......luckily most designs people build are designed around casein glue and its properties.

Somebody said: "Laminate your spars with resourcenal and do everything else with Aerolite". I intend to adhere closely to this advice, but that my spars aren’t laminated and I can't get any Aerolite ;-)

Resourcenal is good stuff and works well, but does require a good fit and proper clamping pressures. When working on certificated aircraft with wood parts, it is often times the only acceptable wood bonding agent.

Epoxy resins are more tolerant of less than perfect workmanship and do not require (or even desire) so much clamping pressure. The bashing of epoxy resins here is a bit overblown and there are hundreds of thousands of epoxy resins, most with their own designed purpose. Not all Epoxy resins are equal. Several, including T-88, work very well for aircraft construction. It is highly unlikely that you are going to approach transition temperatures to where your aircraft may be heat damaged unless it is painted black and lives outside in southern AZ. I have a wood airframe aircraft that is now approaching 20 years old with well over 1000 hours of flight time on it. To date, I have seen -0- failures in the epoxy resins used in construction. This would include all of the fuselage, and the built up box spars.

I have observed a poorly built, aged and weathered example of the same aircraft that was not airworthy tortured to failure using a jacking frame and chains. The distortion of the box spars and airframe before failure was incredible, but the ultimate failures were in the shear webbing of the spars as the webbing plywood finally ripped right down the middle. No failures of the epoxy bonds were observed in the failure testing.

While I do agree that Resourcenal probably has a better bond than T-88 or other epoxy resins, many of the epoxy resins available and recommended for aircraft construction are more than adequate and will exceed the strength of the woods they are bonding.

Cub Builder

I have no doubt that epoxy can be stronger than wood, but:

I want some Weldwood, so 20 min to hdwe store and $10 and I have it. For epoxy, mail off a chunk of bucks to ACS and wait for it to arrive.
To use the Weldwood, pour a tablespoon or so into a dixie cup, mix with water and an icecream stick and use.. Clean up afterward with a damp paper towel. For epoxy, isolate building area from the rest of the house to block fumes. Don gloves mask and other protective gear as required, mix ingredients as required, glue parts, clean up with acetone..

In the end, each way gets the same result, a well glued joint. Why bother with epoxy?

"Works with less than perfect workmanship", = you can get away with sloppy workmanship. Not a message I want to hear in aircraft construction..

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Originally Posted by cub builder

Resourcenal is good stuff and works well, but does require a good fit and proper clamping pressures. When working on certificated aircraft with wood parts, it is often times the only acceptable wood bonding agent.Epoxy resins are more tolerant of less than perfect workmanship and do not require (or even desire) so much clamping pressure. The bashing of epoxy resins here is a bit overblown and there are hundreds of thousands of epoxy resins, most with their own designed purpose. Not all Epoxy resins are equal. Several, including T-88, work very well for aircraft construction. It is highly unlikely that you are going to approach transition temperatures to where your aircraft may be heat damaged unless it is painted black and lives outside in southern AZ. I have a wood airframe aircraft that is now approaching 20 years old with well over 1000 hours of flight time on it. To date, I have seen -0- failures in the epoxy resins used in construction. This would include all of the fuselage, and the built up box spars. I have observed a poorly built, aged and weathered example of the same aircraft that was not airworthy tortured to failure using a jacking frame and chains. The distortion of the box spars and airframe before failure was incredible, but the ultimate failures were in the shear webbing of the spars as the webbing plywood finally ripped right down the middle. No failures of the epoxy bonds were observed in the failure testing.While I do agree that Resourcenal probably has a better bond than T-88 or other epoxy resins, many of the epoxy resins available and recommended for aircraft construction are more than adequate and will exceed the strength of the woods they are bonding. Cub Builder

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I think most epoxy's heat deflection temperature is around 120f, so if you have something under load at those temperatures or above, thats where epoxys fall out of favor from an engineering standpoint. At around 200F most have strengths af less than half of what they have at room temperature. Things that dont see elevated temperatures or constant load are probably the best applications for epoxys when good joinery or clamp pressure are impossible to obtain. Things that see constant load and higher temps, probably a better location for resorcinol or UF adhesives with good joinery and clamping. Designs engineered for casein adhesive are probably a lot safer to replicate with epoxy. If it was originally a high performance design engineered around resorcinol or UF's I would have a harder time substituting a lower performance adhesive like epoxys or caseins. It would be like substituting 6061 for 2024 in a design, and maybe allowances would have to be made for the lower performance.

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Originally Posted by briankk

I have no doubt that epoxy can be stronger than wood, but:

I want some Weldwood, so 20 min to hdwe store and $10 and I have it. For epoxy, mail off a chunk of bucks to ACS and wait for it to arrive.
To use the Weldwood, pour a tablespoon or so into a dixie cup, mix with water and an icecream stick and use.. Clean up afterward with a damp paper towel. For epoxy, isolate building area from the rest of the house to block fumes. Don gloves mask and other protective gear as required, mix ingredients as required, glue parts, clean up with acetone..

In the end, each way gets the same result, a well glued joint. Why bother with epoxy?

"Works with less than perfect workmanship", = you can get away with sloppy workmanship. Not a message I want to hear in aircraft construction..

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Some additional data (counter?) points:

I have built three light aircraft with T-88 epoxy adhesive. I have never tolerated 'sloppy' workmanship but don't consider my craftsmanship to be 'perfect'. I have seen a couple of examples of what I consider 'perfect' and realize I will never have the skill or patience to achieve that level of artisanship. I want my planes to fly within my lifetime.....

T-88 is relatively inexpensive and I can get it shipped via USPS from ACS in two days. A couple of quart kits will build a lot of structure.

Mixing involves squirting out equal length beads of parts A and B on a mixing board (scrap piece of cardboard) and mixing with an ice cream stick.

I have never used gloves, mask, and other protective gear and haven't experienced any unpleasant fumes...fumes...fumes...But vinyl gloves are not a bad idea just to keep it off skin...easier than chewing off a wad of epoxy...... ;)

Cleanup of the joint involves a quick wipe-off with a paper towel while the epoxy is fresh.

But hey....I used TiteBond II on the last set of ribs I built, worked great and the Pietenpol guys love the stuff. :)

This talk of the lack of suitability of T-88 for aircraft construction has me very concerned as my project is almost completely fabricated with T-88. I must say though, I have through out the course of construction made samples for destructive testing and have yet to have an epoxy joint fail at the glue line.
I did do a birch plywood lamination with CASCOPHEN (resorcinol) that failed testing. The test piece split at the glue line and when I tested the actual piece and it also split at the glue line rather easily. To be fair this glue was nearly 2 years old and I suspect that was the problem. I had used the Cascophen on a previous spruce bent lamination about a year before and that test piece was good.
If the strength of the glue line/joint is greater than the material (wood) being glued is there an advantage to a higher strength adhesive? It was said that Oak joints do not glue well but I have some Ash pieces that I tested last night (Glued up months ago) the results are attached.
I have sent System Three an email for their data on cold creep with T-88.
So, at this point, I am not sure if I should accept the information that T-88 is an inadequate product and scrape my project before I go any further or accept that the epoxy appears to be working for me and continue?

http://eaaforums.org/attachment.php?...tid=4451&stc=1http://eaaforums.org/attachment.php?...tid=4450&stc=1

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Originally Posted by amv8vol

This talk of the lack of suitability of T-88 for aircraft construction has me very concerned as my project is almost completely fabricated with T-88. I must say though, I have through out the course of construction made samples for destructive testing and have yet to have an epoxy joint fail at the glue line.
I did do a birch plywood lamination with CASCOPHEN (resorcinol) that failed testing. The test piece split at the glue line and when I tested the actual piece and it also split at the glue line rather easily. To be fair this glue was nearly 2 years old and I suspect that was the problem. I had used the Cascophen on a previous spruce bent lamination about a year before and that test piece was good.
If the strength of the glue line/joint is greater than the material (wood) being glued is there an advantage to a higher strength adhesive? It was said that Oak joints do not glue well but I have some Ash pieces that I tested last night (Glued up months ago) the results are attached.
I have sent System Three an email for their data on cold creep with T-88.
So, at this point, I am not sure if I should accept the information that T-88 is an inadequate product and scrape my project before I go any further or accept that the epoxy appears to be working for me and continue?

http://eaaforums.org/attachment.php?...tid=4451&stc=1http://eaaforums.org/attachment.php?...tid=4450&stc=1

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I wouldn't go running to the scrap bin, luckily most designs are overbuilt by a large margin. Odd you had a glue failure, but considering the shelf life of the resorcinol part B is 9 months, and yours was almost 2 years old......well that's a pretty easy one. In the end its a homebuilt, and you can use what you like. There are production aircraft using epoxy in their wood structure, so its not unheard of by any stretch. Good Luck!

Gday from Aussie chaps,I have read this thread with interest as I am procrastinating heavily about building an aeroplane and just Wanted to make a quick comment .The RAF brought the Mosquito to Australia at the end of ww2(VE) and had to withdraw it as the aeroplane had problems with the spars delaminating. It was only up north in the tropics that the problem became apparent so the Japanese were lucky not to have to face a awesome aeroplane such as the Mossie. The glues used did not seem to like the hot humid weather. I don't know what it was but I know the CAA were against wooden homebuilt aeroplanes for a long time. Cheers Ross