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Old Apr 16, 2008, 08:22 PM
Stay in it!!!!
Riverside, California, United States
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I was thinking of how cool it would be for Discovery or somebody to come out and document the build, maiden flight and record attempt. It would be cool to have Guiness people there to make it official if I ever get it up to a good high speed.. Maybe someday.
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Old Apr 16, 2008, 09:12 PM
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wakumann's Avatar
Canada
Joined Jul 2003
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Nice build tread

Joe
was wondering that no one has a mask, even the fumes of epoxy are quite harmful.
Know a few guys which developed nasty allergies over the years.
Or you have a good ventilation system.

Cheers
Thomas
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Old Apr 16, 2008, 09:43 PM
He bowls overhand
threcixty's Avatar
Falcon, Colorado
Joined Oct 2004
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Ya get sensitized more from touching then breathing.. lol.. that sounds bad! In a shop that size, I doubt that the fumes would concentrate that much..
Joe.. Maybe send something to Mythbusters about a 400 mph glider..
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Old Apr 16, 2008, 11:00 PM
Stay in it!!!!
Riverside, California, United States
Joined Aug 2004
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Quote:
Originally Posted by wakumann
Nice build tread

Joe
was wondering that no one has a mask, even the fumes of epoxy are quite harmful.
Know a few guys which developed nasty allergies over the years.
Or you have a good ventilation system.

Cheers
Thomas
That loud noise in the video's is coming from the ventilation unit in the shop. it pulls a lot of air through the shop. You can feel a breeze. It has a 30 or 35" duct. We were wearing gloves though.
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Old Apr 17, 2008, 12:23 AM
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Melbourne Australia
Joined Jul 2005
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Maybe Myth Busters would be interested in documenting the attempt? If you can't beat the 400 mark, I'd love to see what they come up with to smash it!

Sam.
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Old Apr 17, 2008, 01:28 AM
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daboz's Avatar
HB cali
Joined Apr 2006
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new vid posted warp1.avi, bottom of the page. http://www.rcspeeds.com/160build.aspx

you will need the Divx decoders also located on the page.
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Old Apr 17, 2008, 07:05 AM
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rcgroupie's Avatar
USA, CA, Los Angeles
Joined Jun 2005
533 Posts
Great video!

A couple questions, Joe.

1. Do you vacuum degass the epoxy right after mixing to remove entrained air, or does the rolling process make it moot?

2. Do you warm the epoxy slightly before you roll it in to reduce viscosity, or are you more worried about pot life?

Target: (VARTM)
Quote:
Originally Posted by target
Could you not calculate the amount of resin required, then add a bit for a "fudge factor"?
I would think that this would just result in a small weight penalty, but also add peace of mind.
Target
The issue is not insufficient resin, it has to do with the way the distribution goes. In sort of a crude example, suppose you were trying to coat a canyon with resin using gravity instead of vacuum. If you poured the resin in 'upstream' and drained it out 'downstream' it would only coat the floor of the canyon, and not the walls. Does this make sense?
If these guys are really making a computer model of resin flow, that would be sweet!
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Old Apr 17, 2008, 07:14 AM
Daryl Wallis57's Avatar
Australia, VIC, Creswick
Joined May 2007
490 Posts
Resin infusion

There is a great example of resin infusion in the pix about halfway this page on the HP-24 kit glider site, done in general workshop conditions.

http://www.hpaircraft.com/hp-24/update_4_april_08.htm

Incidentally it is one of the best build threads you will ever read, hard to top this one though! Go Joe!

Dash.
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Old Apr 17, 2008, 07:30 AM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
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Quote:
Originally Posted by rcgroupie
Great video!

A couple questions, Joe.

1. Do you vacuum degass the epoxy right after mixing to remove entrained air, or does the rolling process make it moot?

2. Do you warm the epoxy slightly before you roll it in to reduce viscosity, or are you more worried about pot life?

Target: (VARTM)

The issue is not insufficient resin, it has to do with the way the distribution goes. In sort of a crude example, suppose you were trying to coat a canyon with resin using gravity instead of vacuum. If you poured the resin in 'upstream' and drained it out 'downstream' it would only coat the floor of the canyon, and not the walls. Does this make sense?
If these guys are really making a computer model of resin flow, that would be sweet!
I understand the point you are making now.
Maybe multiple points of resin introduction would be the key, one let in at a time, while the vacuum is continuous??
You're right though, no need for Joe M to be the trailblazer this time.

T
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Old Apr 17, 2008, 12:02 PM
Challenge is rewarding
djklein21's Avatar
San Diego, CA
Joined Aug 2004
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Quote:
Originally Posted by target
I understand the point you are making now.
Maybe multiple points of resin introduction would be the key, one let in at a time, while the vacuum is continuous??
You're right though, no need for Joe M to be the trailblazer this time.

T
The trial and error part, is to place the infusion and extraction ports in locations such that the flow front never encircles a dry area, cutting the air off from the vacuum and leaving you with a dry fiber spot.

Again, please start a new thread as I don't want to clog up Joe's awesome build thread with a completely different topic.

Also, there are many commercially available VARTM flow modeling software packages, but none for 3-D flow, which captures the through thickness flow. Anyway, a new thread huh.
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Old Apr 17, 2008, 12:12 PM
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HB cali
Joined Apr 2006
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Weight Penalty

Weight isn't that big of a deal, for DS, right? Seems, "to me" most planes @ over 200/250 seem as though they would fly better heavier. I like Opii ballasted all the time... 110oz @ 75inches. Joe will have a lot of wing area too, ?
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Old Apr 17, 2008, 02:57 PM
Challenge is rewarding
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San Diego, CA
Joined Aug 2004
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Total weight isn't, but mass, and mass location are a very big deal for flutter. Most seem to overlook this, and only consider stiffness. When building an aileron, the heavier the surface, the larger its mass moment of inertia, and the further back its CG as compared to the hinge line all drop the flutter speed. Also the shear stiffness of a laminate is very sensitive to the amount of epoxy. The more epoxy, the worse the shear performance of the laminate.
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Old Apr 17, 2008, 06:03 PM
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HB cali
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Well, many of us consider it, and many of us like our planes much heavier than they come for the 250/300mph range. SO, we add steel rod into all our ailerons, ruddervators, elevators and flaps to move the cg of the control surface forward and to increase torsional stiffness. Some glue in ballast. Others glue brass or lead into the wing tips and or the leading edge of the wings. I posted a document on aerodynamic flutter that address mass balancing.

Still, IMO, mass for high speed DS seems to be a friend,,, in the right place.

Chris

http://www.rcgroups.com/forums/showt...hlight=flutter
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Old Apr 29, 2008, 06:56 PM
Say when.....
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United States, MO, Hillsboro
Joined Sep 2005
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Kinda quiet here in Dynamic-land. Any updates for us Joe?

--quigley
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Old May 06, 2008, 07:37 AM
Stay in it!!!!
Riverside, California, United States
Joined Aug 2004
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Finished the inner skins yesterday. There were two of us working and it was a mad dash to get all of the pieces into the molds before the resin went off. Couldn't take any pics. Basically I used a couple fabric doublers in the tips with 1/16th balsa in between, two more layers for control surface doublers, kevlar hinge, several pulls of tow in the LE several pulls of tow and a few layers of fabric in the tounge and a full inner layer of carbon fabric to cover it all up. The skins are finished! All I need to do now is make a shear web, drag spar, install gear, and a couple of other small doodads and I can close the molds. I will have a wing by the weekend if I can get all the servos.
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