Happy to help; you can reach me directly over email at jmuck78 - at - me.com if
you have any other questions or want photos.
Sent from my iPhone
On Jul 24, 2019, at 1:18 PM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
On Jul 24, 2019, at 12:36 PM, Jason Muckenthaler <jmuck78@xxxxxx> wrote:
Richard,
Thanks for that, and i look forward to seeing what you find. The rail
buttons were new, never been launched, and i had made a point to install
them so that they rotate freely. Before the launch, i was able to easily
rotate the button around the screw.
Sent from my iPhone
On Jul 24, 2019, at 11:01 AM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
Jason:
I don’t think ROC has a launch pad like you are describing. However, there’s
the “Super Uber” pad which has much greater capability and I do think a very
large and stable pad is always a good idea. The Super Uber wasn’t there for
this launch.
Anyway, good for you analyzing what happened to your rocket and posting the
video from Greg Smith’s launch. I’m wondering how many people watched this
video? Really, thank you for posting this info. You see, we have a bit of a
mystery on our hands and I think you have helped to solve it. About this and
the rail button damage you experienced, I’m doing some simple checking with a
set-up in the garage and will be posting some photos later today.
Things that could help in my checking: Were the rail buttons on your rocket
used previously? Were they pretty tight on the rocket or were they able to
rotate?
In an email to Kurt and Mike recently, I wondered why many of the rockets we
see taking weird flights off the rail are going to the right. I don’t have
numbers, just observational reckoning. Most of the time, the significant
wind is coming from the West, and you can see wind cocking as an arc towards
the West (left on the range). But, your rocket goes wonky on the pad and off
the rail, not arching West immediately.
I suggest we think about this more… The blast deflector is V shaped. If the
wind is blowing from the West it might push the rocket on the rail to the
right.. The thrust of the motor will be concentrated on the right side of
the V blast deflector. The rocket can only be influenced by the blast
deflector because it’s attached to the pad with the rail. If the base of the
pad moves left during the launch, where is the top of the rail going to go?
(Where is the CG as this is happening? Wow, interesting!) What will be the
angle of the rail with the rocket moving up the rail? And, if the rail is
moving, how will it be moving? Will it be straight or slightly curved (maybe
in two different directions)?
Richard
On Jul 22, 2019, at 7:19 PM, Jason Muckenthaler (Redacted sender "jmuck78"
for DMARC) <dmarc-noreply@xxxxxxxxxxxxx> wrote:
Unistrut: I probably used the wrong term, I was attempting to refer to a
launch rail (that ROC may or may not have) that has a truss structure with a
rail attached. Yes, the M-impulse was launched on the back row.
The rocket did slide nicely on the rail when we loaded it; the 46 lbs weight
is launch weight with the ~ 10 lb motor (36 lb dry weight).
The shock cord might have been able to damage one of the rail buttons, but I
think it’s unlikely the shock cord managed to damage both rail buttons in
the same way. The main chute did deploy at apogee inadvertently because the
shear pins were too small, so there wasn’t much opportunity for the shock
cord to get tangled up during a free fall.
There is also a small, but noticeable “waggle” visible in the launch video
that could be due to the thrust vector misaligning with the rail direction.
The rocket also seems to have a high spin after the initial waggle
stabilizes.
Here’s the launch video:
https://www.youtube.com/watch?v=K_RToX5yihc ;
On Jul 22, 2019, at 6:59 PM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
What’s the unistrut rails? The M-impulse went off the back row I’m
assuming and unless the Super Uber was there (and I don’t think it was),
there is only one kind of pad on the back row.
Doesn’t look like drag damage to me. Most of the available rail buttons
are pretty tough and would just plow through the surface of the lakebed.
Did the rocket slide on the rail nicely when it was installed? 46 lbs is a
heavy rocket even for a M. Could the shock cord have caused the damage
during deployment?
Richard
On Jul 22, 2019, at 6:28 PM, Jason Muckenthaler (Redacted sender "jmuck78"
for DMARC) <dmarc-noreply@xxxxxxxxxxxxx> wrote:
After retrieving the LOC Hawk on Saturday, I noticed that both rail
buttons had been damaged with very little damage to area immediately
surrounding the rail button locations. My initial, knee-jerk reaction was
that the rail button damage was just another consequence of the rocket
being carried across the lakebed, but on further reflection, I wonder if
the damage was actually caused during the launch. The wind was blowing at
a healthy pace (while still less than the 20 mph limit) and the rocket has
quite a large fin area. The large fin area coupled with a potential
torque due to the nozzle exhaust hitting the blast deflector at an angle,
may have been enough to shear the outer edges of the rail buttons off
before the rocket cleared the tower.
I have attached pictures of the two rail button locations, and there is a
clear lack of road rash in the vicinity. The other possibility is that
the rail buttons impacted something during its trip along the lakebed, but
if that were the case, I would have expected the rail button screws to
show some deflection or some other impact damage - but there is no such
visible damage to the rail button screws.
I am also now curious if I should have used one of the larger unistrut
rails instead of the 1515 rail tripod. I don’t know where the cutoff for
using the 1515 tripod launcher is versus the unistrut rail (and I should
have asked prior to the launch, but it didn’t occur to me until I saw that
rail buttons). Does anyone else have any similar experience with broken
rail buttons like this, or does this look more like damage from wind
carrying the rocket across the lakebed, and I’m just not recognizing it?
Some Data: The Lift off weight was about 46 lbs with the M1297. Velocity
off the rail (according to OR) was about 40 mph.
Greg Smith has a nice video of this torque on his blog from 2016 here:
http://hawtakshun.blogspot.com/2017/01/lucerne-dry-lake-november-2016-l1500-is.html
Thanks,
Jason
<IMG_8200.jpeg><IMG_8201.jpeg>
