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 #902
Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042
Dr. GigaVolt wrote ...
DaJJHman wrote ...
just make sure that your motor timings are not even slightly off... it is a VERY bad situation, but it was different than I expected (in case this never happened to you): it goes off, with say one motor igniting later, so it goes off course, but once all the motors are in near sync in their thrust output, it flies strait like normal, then off again when the other engines die before the last one goes out... had an issue with this a while back, don't let that happen to you...
also, who are you getting the motors from? some companies, at least that I have seen, design some of their engines for cases like these where smoke is wanted.
Yes. Simulataneous firing of the clusters is a must, especially in this configuration. (Typically, there is a larger central motor which provides enough thrust to safely lift rocket in the event the outboards don't light properly)
Magnesium based thermite is being used to ignite the motors.
The first test runs will utilize commercial motors (about $3200 for the flight when you factor in the price of (4) 75mm aerotech reloadable cases) Subsequent flights will be on EX motors i'm designing and building myself which includes cases as well.
a central motor wont help if one of the outboards does not light (while others do) as those others will cause unequal force, making the rocket diverge off course (unless you have some serious design considerations, but from the looks I took of your pics it does not seem like those are in place unless I am missing something)... and don't say that you are wiring in series or some special configuration as they are not always reliable (especially series electrical connections, as one goes off and breaks the circuit before others can.)... I am sure you have thought of something that I am missing, but I would like to hear it, as I love doing clusters myself but have had some issues...
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
wrote ...
and don't say that you are wiring in series or some special configuration as they are not always reliable (especially series electrical connections, as one goes off and breaks the circuit before others can.)... I am sure you have thought of something that I am missing, but I would like to hear it, as I love doing clusters myself but have had some issues...
The firing circuit itself utilizes low current electric matches (typically 2 in parallel for each motor) and then the entire (4) sets wired in parallel. These electric matches then ignite thermite which almost guarantees simulataneous ignition of all motors. Another technique is to actually use smaller motors pointing upwards inside the main motors (i.e. Estes C motors are commonly used)
And whatever method you employ, considerable ground testing is required (even at the day of the launch to ensure the pad electronics have enough juice to ensure ignition)
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.
3/4 Scale Nike Smoke Rocket
