My AC in the garage wasn’t able to keep up today. The “feel like” in Temecula
today is less than very uncomfortable, and you can use your imagination what
that is. ;-( So, I’ll finish up with the photos this evening.
Thank you for the info Jason.
Richard
On Jul 24, 2019, at 12:36 PM, Jason Muckenthaler
<jmuck78@xxxxxx<mailto: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<mailto: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<mailto: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<https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DK_RToX5yihc&data=02%7C01%7C%7Cb7a155ac699944893a4208d7106e4387%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636995938070980674&sdata=MACY8xS4q080ToYIPOM5UmUhYtfm%2BoMzYPibcD6J7F0%3D&reserved=0>
On Jul 22, 2019, at 6:59 PM, R Dierking
<applerocketry@xxxxxxxxxxx<mailto: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<mailto: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<https://eur04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fhawtakshun.blogspot.com%2F2017%2F01%2Flucerne-dry-lake-november-2016-l1500-is.html&data=02%7C01%7C%7Cb7a155ac699944893a4208d7106e4387%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636995938070980674&sdata=gTSP4jX0mlGTnH1Fske8YZwO7sjbvxTs%2FDpuZic3em0%3D&reserved=0>
Thanks,
Jason
<IMG_8200.jpeg><IMG_8201.jpeg>
