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aeroknot

More epoxy & glass questions?

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Posted (edited)

Sorry if I start a fight here, but......

 

The Canard airplanes currently popular (non-kit) Long/Open EZ and Cozy Mk IV are great planes and very well supported.  I hope to use my boat building experience and technics and apply them to building aircraft.

 

Here's my question up for discussion.  They use 30+ year old construction technology and the approved vendors and materials are 30+ years old.

 

Fiberglass these days have a multitude of new weaves and cross sections (biax & triax with or without mat, woven) and are measured in ounces per yard instead of thickness.

Fiberglass, Kevlar, and carbon fiber.

There are dozens if not more, more advanced resins on the market.

 

Is it possible to build a lighter/stronger (less expensive) plane using more current technologies and materials???

Edited by aeroknot

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Is it possible to build a lighter/stronger (less expensive) plane using more current technologies and materials???

So my first question when folks ask about different materials, etc. is "What problem are you trying to solve"?

 

The airplane does not need to be stronger - no Long-EZ or COZY has ever had a structural failure in flight when built anywhere near the plans specifications.

 

Unless you're going to use non "moldless construction" methodology - meaning building molds and using vacuum bagging type techniques, you're not going to substantially reduce the amount of epoxy in the build. You can't substantially reduce the thickness of most of the layups, because strength isn't necessarily the driving factor - damage tolerance on fuselage and wing skins is. So you're really not going to make them any lighter by changing cloth or epoxy - you could use lightweight engines, instruments and systems and save a lot more weight than you ever would with layup changes.

 

Whether a fiberglass weave is measured in oz/sq-yd or in thickness is meaningless - you need a certain amount of glass to provide the stiffness/strength/puncture resistance required.

 

Using Carbon in a contact (non-vacuum bagged) layup for structure is contraindicated, so unless you're going to bag everything, you should not use carbon (and it's way more expensive than glass, negating one of your goals).

 

Kevlar is right out, as it has really crappy compression capabilities. There may be one or two places where a bit of Kevlar could be useful (under the nose puck for scraping resistance, for example), but nowhere else.

 

So the short answer is really "no". Unless you're going to redesign the airplane to use different materials or build techniques (and it's been done - see the Berkut, which doesn't weigh any less and usually more than a Long-EZ) you're not going to be able to make the build time shorter, the airplane cheaper or stronger by changing materials.

 

Feel free to argue the point - many have over the past 25 years - but none have shown one instance of any of their arguments holding water. These planes are what they are, and they're pretty well optimized from a design standpoint with respect to a balance of build time, cost and structural capabilities.

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As Marc said ..... yes you could but it's going  to cost you.

By the time you build a one off mold, you could have built the plane. 

 

If you want to see some different techniques that would render a lighter weight airframe (where money is no object) then stop by the Vacuum Infusion demo at Oshkosh during AirVenture. We will be building a fuselage of a new design using Vacuum Infusion and molds. These molds are made from plugs that start out as CNC milled foam ….. so as you can imagine, just building the molds involves quite a bit of technology and $$$. Now, if you were building a kit, then you could justify the expense.

 

As for the Berkut, I'm sure that we could demonstrate how Vacuum Infusion could reduce the weight of that aircraft considerably, so your point about newer technology and techniques is well taken.

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My apologies, for my ignorance.  I have two or more flaws to my thinking. 

 

One, I come from the marine environment and have little or no knowledge of aircraft construction, building techniques and terminology.

Two, I am so used to purchasing products in the marine business wholesale and hate the thought of spending retail cash.

 

on the plus side, I can still learn and I can follow directions.

I have built several boats, fiberglass and wood using a variety of resins and composites and construction techniques.  Have hand formed several plugs for mold construction.

 

Please bear with me while I learn and grow in this field.

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Posted (edited)

Class A mold from what I can see.

 

Of note: A boat builder started Velocity.

Edited by TMann

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Nice plugs. Hereis a chap who has made molds.

http://www.canardzone.com/forum/topic/19036-a-solution/page-1

http://forum.canardaviation.com/showthread.php?t=4928

 

I talked to him this year at Sun n Fun. He was hopeful but he’s been at it this project around 10 years and flying is still a long way off. He’s in Lakeland. If you build to plans you can build one of these in 2-4 years.

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He was hopeful but he’s been at it this project around 10 years and flying is still a long way off.

Bob usually stops by the Vacuum Infusion demo during AirVenture so we get a chance to catch up.

That said, there are a lot of builders that are well beyond that 10 year mark as well as some that have brought it in under a year.

 

They guy I typically fly to Oshkosh with built his RV in less than 9 months. Another guy in the chapter is still working on his Berkut. He's the original owner of kit #8.

 

It's all about man-hours not how long you've owned the parts.  :D

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It's all about man-hours not how long you've owned the parts. :D

And $$$

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Talking with a guy on another forum and he uses

 

Pro Set LAM-125 Low Viscosity Laminating Resin
Pro Set LAM-229 Slow Laminating Hardener

 

Seems like it can be had for around $90 +/- per gallon.

 

Any opinions on this stuff?

 

BTW] How many gallons for building a LongEZ or Cozy Mk IV?

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Talking with a guy on another forum and he uses

 

Pro Set LAM-125 Low Viscosity Laminating Resin

Pro Set LAM-229 Slow Laminating Hardener

 

Seems like it can be had for around $90 +/- per gallon.

 

Any opinions on this stuff?

 

BTW] How many gallons for building a LongEZ or Cozy Mk IV?

 

If you're going to build a LE or COZY, you should review the documentation for approved materials. There is a list of approved epoxies in the CP's and COZY newsletters. Proset 125 with 226/229 hardeners are approved epoxies.

 

If you can get it for $90/gallon (including the necessary hardener), you should become a distributor. ACS sells resin gallons for $119 and hardener 1/3 gallons for $75 - $85. So a "kit" is about $200.

 

I just bought 5 gallons of 125 from CST Sales for $104/gallon, and the 226 and 229 hardeners were $72 per 1/3 gallon.

 

What's nice about the slow hardener (229) is that you get a nice long pot life with low viscosity for easy wet-out, and with even a low grade post cure get a reasonably high Tg and HDT. Even without a defined post-cure, the HDT is around 130F.

 

IIRC, I used about 10 - 12 gallons of resin (not counting hardener) for my COZY MKIV, not counting West 105/205/205 for the micro finishing.

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