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Q1 Parts List.

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14 years 6 months ago - 14 years 6 months ago #723 by haiqu
Replied by haiqu on topic Re:Q1 Parts List.
SteveC68 wrote:

I wouldn't use West Systems either I would use MGS, it has better viscosity and longer pot life and stays thin longer than any other. It's mechanical properties are better than Saf-T-Poxy. Or I might use ProSet (good enough for SpaceShip 1 good enough for me).


In my case the lead time from the USA is just too long, I have to use something locally available. If West can convince me that their epoxy system is as good as the original I'll use that. It's being manufactured here for boating uses and I can buy it off the shelf at three locations within 10km.

I probably wouldn't put a lot of stock in the "testing" that was done in the design of the Q1 back in the 70's. Have you seen their "wind tunnel"? There is a picture of it in the plans.


If you're referring to Burt's cartop airfoil testing, yeah. Pretty smart actually, use what you have until you can afford something better. The VariEze was formally tested by the US Army in a proper tunnel. Close to expected results too. I have no qualms about anything Burt Rutan has designed, which is more than I can say for some.

The load test was a bunch of guys standing on the wing. I don't recall reading, seeing or hearing about any destructive testing done either. Remember that composites were in their infancy at the time so everything was "experimental".


Not so. If you read Canard Pusher 36 you'll see where Burt found out someone was selling cheaper glass with the same part numbers, so he tested it to destruction. He found the stuff initially fractured at 61% of the original specification and warned people about using it. Destructive testing was also done on VariEze canards and the properties of the materials he was using were very well known.

I would love to see Rutan's engineering notes on the Q1.


Somewhere, I've got copies of his original design sketches and notes for the Model 40 "Quickie" prototype ...

Rob
Last edit: 14 years 6 months ago by haiqu.

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14 years 6 months ago #727 by SteveC68
Replied by SteveC68 on topic Re:Q1 Parts List.
I've seen some of the design sketches, but again those are a far cry from an engineering analysis. I'm not doubting his design ability in the slightest. What I am doubting is that anywhere near the analysis as what is done today was done in the mid 70's when the Q1 was designed. Testing is and was very expensive and Burt wasn't exactly rolling in the cash at that time. So a few tests of his fabrics were probably done and that data extrapolated into various designs. FEA was a long way off so computer modeling was out. Without it the only real way to know the airframe capabilities at that time would have been destructive testing on a completed airframe. I just don't think that was ever done. And the car as a wind tunnel as far as I have read was done well after the kit was released into the wild and there were questions as to the performance hit of the canard with a rough/wet/dirty surface.

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14 years 6 months ago - 14 years 6 months ago #728 by haiqu
Replied by haiqu on topic Re:Q1 Parts List.
SteveC68 wrote:

I've seen some of the design sketches, but again those are a far cry from an engineering analysis. I'm not doubting his design ability in the slightest. What I am doubting is that anywhere near the analysis as what is done today was done in the mid 70's when the Q1 was designed. Testing is and was very expensive and Burt wasn't exactly rolling in the cash at that time. So a few tests of his fabrics were probably done and that data extrapolated into various designs. FEA was a long way off so computer modeling was out.


You have to realize that computer models are built from the data that guys like Burt provided in the first place. I've built electronics circuits that failed in circuit simulators but worked just fine, because the simulator didn't model some seemingly trivial parameter. And anyone who has designed an airplane in X-Plane's Plane Maker will know how badly they can behave when flown in the simulator.

Without it the only real way to know the airframe capabilities at that time would have been destructive testing on a completed airframe. I just don't think that was ever done. And the car as a wind tunnel as far as I have read was done well after the kit was released into the wild and there were questions as to the performance hit of the canard with a rough/wet/dirty surface.


The team at RAF investigated every hard landing for years to ascertain 1) whether a design flaw had caused it and 2) how intact the aircraft was after the crash. The best data I can see is people doing stupid things and walking away, and there are many people who thank Burt's engineering for still being alive.

The rooftop wind tunnel tests were started way back in 1972 when Burt was still developing the timber VariViggen prototype. He used known and predictable NASA airfoils, or in the case of the LS1(Mod) that replaced the GU he used a design newly developed and tested by John Roncz, whose work he knew first-hand. All critical structures were over-engineered and tested to twice their rated static loading.

When you're working at the bleeding edge it helps to use what you do know very conservatively, and that's the mark of a brilliant engineer.

Rob
Last edit: 14 years 6 months ago by haiqu.

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14 years 6 months ago - 14 years 6 months ago #729 by haiqu
All parts list call-outs for asbestos for the firewall or gaskets should be replaced. It is illegal to use asbestos now in most countries. In the case of the firewall, a spray-on substitute was already tested and approved in the Quickie newsletters.

I have also confirmed with the local West System respresentatives that West 105/205 is NOT suitable for airplanes as a structural adhesive. Those wishing to use this company's epoxies should be using West ProSet 125R/229H for all structural parts. See ASTM test data comparisons here:

www.fibreglast.com/contentpages-System+2...rison+Chart-319.html

Rob
Last edit: 14 years 6 months ago by haiqu.

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14 years 6 months ago #731 by haiqu
Replied by haiqu on topic Re:Q1 Parts List.
SteveC68 wrote:

The spreadsheet indicates there is an RAES and an RAEF resin, yet the plans indicate there is an RAE resin and you make it RAES (slow cure) and RAEF (fast cure) by adding either slow or fast hardener. I would guess the total amount of resin needed would be 8 gallons sum of the two different types on the spreadsheet, but that's just a guess. Then 7 quarts of fast hardener and 1 quart of slow. That last part seems backwards to me as after reading through the plans a couple of times the majority of the plane is both assembled and covered with slow cure.

Steve


This made me curious so I checked the plans. The majority of the Quickie is built using the FAST epoxy, according to the education section in Chapter 3. RAES was used for joining foam blocks mainly, to avoid exotherm.

Rob

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14 years 6 months ago #732 by SteveC68
Replied by SteveC68 on topic Re:Q1 Parts List.
You are right about the RAES and RAEF, but it does say that slow can be substituted for fast if the temperature is above 80F. I live in Houston, Texas so the temperature is always above 80F. Also I'm not sure that I could do the wing layups before the fast started to kick. I mean it says right in the plans that the wing layups are 4 hours. Your first layer/ply will be practically completely setup by the time you are putting on your last layer/ply. As a rule of thumb I've noticed that faster curing resins tend to be thicker and thus more difficult to wet out than slower curing. Although not by much.

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