Some people place an additional guide a few inches above the bottom guide to
address this issue.
Sent via the Samsung GALAXY S® 5, an AT&T 4G LTE smartphone
-------- Original message --------
From: "Adrian P. Bailey" <adrian@xxxxxxxxxxxxxxx>
Date: 06/15/2015 12:55 PM (GMT-08:00)
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Launch Pads and Interest Posting for Construction of
Large Launch Pad
Max and I used rail buttons for the first time this weekend, on his Mirage. I
had the same thought when we were attaching them. It turned out to be a
straight flight (but not nearly the forces involved in what you guys were
doing). The continuous rail guide seems like a great idea! From:
roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On Behalf
Of Kurt Gugisberg
Sent: Monday, June 15, 2015 11:35 AM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Launch Pads and Interest Posting for Construction of
Large Launch Pad Richard, I'm not sure if stiffer rail is really the answer.
Last year at XPRS, there was a pad out there that had a triangulated super
structure that kept the long rail straight and it was on a huge base anchored
to the ground and I think it even had guy wires. I watch for four days as
rockets came off of it and kicked out at an angle just like on our loosey
goosey pads. Asymmetric thrust might be one reason but this pad had a long
rail that should have helped. I'm beginning to think it might have something
to do with the spacing or location of the rail buttons. The fact that one
button is off the rail prior to the second one may allow it to torque sideways.
I wonder if one continues rail guide would solve that. Kurt On Mon, Jun 15,
2015 at 9:55 AM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:First, I’m
wondering how much stiffer a 1515 is than a 1010 rail? Cross section is 50%
more, so approximately double? One of my last fights over a year ago now (way
too long ago) was a K1275R off one of the back pads using a 1010 rail. The
rocket went noticeably West immediately after leaving the rail and it wasn’t
the wind. Luckily, the rocket landed close to the pad because of the wind
during descent. One time the wind really helped. There’s always a lot of
discussion about rocket stability, but think about how important a reliable
launch pad is. Of course, what engine in what rocket is very important to how
massive/stable the pad must be and how long the guiding structure should be.
Regardless of size, I think there is some occasional thrust vectoring with AP
engines that takes place moments after ignition that seems to stabilize. What
would be the reason that some rockets left the rail in the Punisher drag race
at an angle? I’m curious if other people believe momentary thrust vectoring
occurs? If you are going over say 10K’ in a location like Lucerne Dry Lake,
you need to be reasonably sure that the rocket is stable (of course), and that
it’s going to fly in the direction you choose. I’ve been considering launch
pad designs for several years, and checked out all the custom pads at the last
two BALLS launches I’ve gone to. Some are really cool with elaborate pad leg
designs and lifting mechanisms but the ones with a sturdy/stiff launch rail
adequately supported along its entire length seem the best to me. This is my
opinion, and I might be a little jealous of the money some spend on their
launch pads. I’m considering purchasing a 12’ x 5” utility trailer for the
base of a launch pad that would also be a platform for a test stand. The pad
would use the triangular aluminum tower material that seems to be popular for
many large launch pads. A link follows that shows a base for an antenna tower.
I would like to know if anyone else is interested in participating in the
construction of a large launch pad/test stand. It would serve as our launch
pad/test stand at ROC and FAR launches and be very useful for XPRS/BALLS.
http://www.dipolnet.com/footing_for_aluminum_antenna_tower_E9151.htm Richard
Dierking
