If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Patrick wrote ...
I found this source which explains some of the trade offs of the differetn fibers.
Yep. Pretty much says 'S' type glass and epoxy is a good 'all round' material, especially for early development of a project, due to ease of use and cost. Carbon and kevlar 'may' have some advantages in specific applications, but there are trade offs, eg brittle failure of carbon. (glass is tougher and will survive more 'crash landings', but some weight savings 'may' be possible using carbon).
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ash Small wrote ...
If you need to save weight, carbon will help stiffness, but at the expense of not being able to survive a crash landing.
Kevlar is usually added where impact/abrasion resistance is required. I'm not sure it will be appropriate in this instance.
Im building version 2 now, it should whiegh in at around 250 grams. As opposed to version 1's 631 grams. Ill use Bass wood, Balsa, and CF. Then ill do some destructive testing and well see if i need kevlar.
Doesnt the kevlar/CF hybrid resist the CF's tendency to crack and fold up?
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
In general, thin-wall carbon tubes are cast in a vacuum bag around a metal mandrel to remove excess polymer. They usually remove the metal form because it would add negligible structural strength to the item. Likewise, balsa wood offers little over foam for structural support.
Kevlar has quite a few issues I won't discuss here, but it can make the material more flexible in general...
Based on the scale: * Polystyrene foam board * Carbon tissue-paper or adhesive vinyl model aircraft skin * Enforce with long-strand stock from an RC shop selling carbon-fiber wing struts * The EDF thrust vectoring nozzles are mostly plastic lined foam
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ive just setup the first FG S2 type 9 inch duct. the S fiberglass and the MAX1618 epoxy are far superior to the E glass and general purpose finish epoxy i was told to use.
the S glass is real nice, doesnt fray, almost negligiable in stiffness before wet-out. the new Max epoxy is so easy to wet. Just laying the glass cloth out and it draws the eoxy in better at 75 F than the old epoxy at 95 F. i expect this one to have some minor defects as its the first round ive made out of FG, but i plan to make 10 to 15 of the ducts as theyre the first parts to get broken off while flying into window and door openings.
The thin epoxy also drips out and prevents excessive build, for much lighter parts than my previous method.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Patrick wrote ...
Doesnt the kevlar/CF hybrid resist the CF's tendency to crack and fold up?
The kevlar will 'hold things together' when the carbon fails.
Patrick wrote ...
Ive just setup the first FG S2 type 9 inch duct. the S fiberglass and the MAX1618 epoxy are far superior to the E glass and general purpose finish epoxy i was told to use.
the S glass is real nice, doesnt fray, almost negligiable in stiffness before wet-out. the new Max epoxy is so easy to wet. Just laying the glass cloth out and it draws the eoxy in better at 75 F than the old epoxy at 95 F. i expect this one to have some minor defects as its the first round ive made out of FG, but i plan to make 10 to 15 of the ducts as theyre the first parts to get broken off while flying into window and door openings.
The thin epoxy also drips out and prevents excessive build, for much lighter parts than my previous method.
I did suggest using 'S' glass right at the beginning of this thread. Who told you to use 'E' glass?
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Differences between good fiberglass, and good Carbon fiber.
