Isn’t a bird in the air worth two on the pad? ;)
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On
Behalf Of Kurt Gugisberg
Sent: Monday, June 15, 2015 4:36 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Launch Pads and Interest Posting for Construction of
Large Launch Pad
I don't know about that white rocket but the yellow and black on the pad sure
looks good. ;-)
Kurt
On Mon, Jun 15, 2015 at 4:24 PM, Adrian P. Bailey <adrian@xxxxxxxxxxxxxxx
<mailto:adrian@xxxxxxxxxxxxxxx> > wrote:
We weren’t in the drag race but here’s a pic of Max’s Mirage launching, if it
helps. The rail buttons were at the bottom and just below the unloaded CG. The
rail was angled into the W.
From: roc-chat-bounce@xxxxxxxxxxxxx <mailto:roc-chat-bounce@xxxxxxxxxxxxx>
[mailto:roc-chat-bounce@xxxxxxxxxxxxx <mailto:roc-chat-bounce@xxxxxxxxxxxxx> ]
On Behalf Of R Dierking
Sent: Monday, June 15, 2015 2:07 PM
To: roc-chat@xxxxxxxxxxxxx <mailto:roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: Launch Pads and Interest Posting for Construction of
Large Launch Pad
So, were the buttons on everyone's Punishers installed at the same locations?
Sent from my iPhone
On Jun 15, 2015, at 1:49 PM, "Kurt Gugisberg" <kurtgug@xxxxxxxxx
<mailto:kurtgug@xxxxxxxxx> > wrote:
I was wondering about the button placement too. My top button is well below
the cg by 6" or so and the bottom button is screwed into the bottom centering
ring. So the rocket under thrust is probably trying to rotate around its cg.
So as perhaps as EJ said, one at the cg and one ahead would be the best
location.
Kurt
On Mon, Jun 15, 2015 at 12:41 PM, E J <ejackson1075@xxxxxxxxx
<mailto:ejackson1075@xxxxxxxxx> > wrote:
I was just skimming and this reminded me of a tip I got many moons ago, but
never really tested. It was off the ancient news boards
(rec.rockets.something), but the tip was to put one guide/button at the center
of gravity and the other a couple calibers above it. The idea was to keep the
contact points from being somewhere that would exert more force on the rocket
than needed to keep it from falling off.
On Mon, Jun 15, 2015 at 11:35 AM, Kurt Gugisberg <kurtgug@xxxxxxxxx
<mailto:kurtgug@xxxxxxxxx> > wrote:
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
<mailto: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
