I may be biased, but I thought it was definitely worthwhile and interesting.
On Jul 25, 2019, at 1:17 PM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
I have a question for you all, and please be open and honest. I was
considering just dropping this last night maybe because I thought there might
be some controversy and dropping it would have been much easier. I do have
other interesting things to do.
Should I have posted or not?
Richard
On Jul 25, 2019, at 12:38 PM, R Dierking <applerocketry@xxxxxxxxxxx
<mailto:applerocketry@xxxxxxxxxxx>> wrote:
Thank you for mentioning that Greg. Yes, Kurt and others did see that move
during the video.
One of the best things about helping to set up the range is learning how the
launch equipment goes together. Don’t take launch pads for granted. Once
you help set up, you find that you become aware of important things outside
of your rocket that affect launching and success.
Some things like bolts that tighten various parts of the pads have wings for
hand-tightening. That’s why I tried to emphasize not to strip things by
over-tightening using something like channel locks. Channel locks should
only be used to pound on things. (Sorry, JK of course.)
However, even if things are tightened properly, I am suggesting that there
are other potential things that should be studied more and addressed. I
think the middle and even those large pads in the back row are moving during
some launches.
Don’t take things for granted, and also, don’t just accept things. Think
critically of how things work, not of other people. Otherwise, we will not
move forward with improvement.
Richard
On Jul 25, 2019, at 11:52 AM, Gregory Lyzenga <lyzenga@xxxxxxxxx
<mailto:lyzenga@xxxxxxxxx>> wrote:
On Jul 25, 2019, at 11:23 AM, R Dierking <applerocketry@xxxxxxxxxxx
<mailto:applerocketry@xxxxxxxxxxx>> wrote:
I did some evaluation of 5/16” rail buttons on 1515 rail. It’s the same
rail that ROC uses for 5/16” buttons on some of the back pads. I believe
it’s called 1515 because it’s 1.5” x 1.5” extruded aluminum with a
channel. 1010 rail is 1.0” x 1.0” and the 1/4” buttons fit that rail.
There are a different suppliers of rail buttons and they are typically
made of Delrin or Nylon. Since the recent post showed damage with a
Delrin, I took some I had and checked them. Basically, I wanted to get a
‘feel’ for what might be happening and how important this could be. I’m
going to try and keep this short with a few photos. But, there’s a lot of
info. I would like for people to comment.
…snip…
Now, remember, the blast deflector can only influence the rocket because
it’s connected to the rail through the pad base. If the base of the pad
moves during the launch, all sorts of things can happen.
I’m not suggesting that people remove the blast deflector on the ROC pads.
That’s up to Kurt and the Board. However, as a flyer, there’s some
things you could do. First, check tightness on all the fasteners on the
pad, but don’t strip them.
This raises a point that occurred to me a few days ago when this subject
first came up, but I didn’t mention it at the time. It has to do with the
question of an asymmetric torque from the blast deflector. As Richard (and
others) correctly point out, the blast deflector can only transmit a torque
to the rail and rocket if the base of the pad is free to move. But those
pads are nicely stuck into the surface of the playa with some substantial
mass and don’t seem to be going anywhere. BUT… There is a freely rotating
joint between the pad base and the head that holds the rail and deflector
on our back row pads. Normally it is secured from rotating by a heavy lock
knob that is tightened by hand. However if when the range is set up, or
when a flyer is placing their rocket on the pad, they neglect to tighten
this lock knob, the deflector and rod can very definitely rotate about the
vertical axis in the manner that is speculated here (and appears to be seen
in the YouTube video). So I would suggest that we all be mindful and aware
of the status of that lock knob when using the back row pads, especially
with high thrust motors.
- Greg
----------------------------------------------------------
Gregory A. Lyzenga <lyzenga@xxxxxxx <mailto:lyzenga@xxxxxxx>>
Dept. of Physics, Harvey Mudd College (909) 621-8378
<tel:%28909%29%20621-8378>
Claremont, CA 91711-5990 mobile (626) 808-5314
<tel:%28626%29%20808-5314>