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hallow it scott manley here with a
Kerbal space program video because well
i haven't done one in a very long time
and honestly I've been struggling
talking about the history of the Chinese
rocket program that I decided to stop
and do something light well I decided
that I would try to fly to the moon in
Kerbal space program using nothing but
solid rocket motors after all we've just
had the more boosters update which added
more boosters including the thoroughbred
and the Clydesdale boosters now these
are two point five meter boosters and as
well as providing lots of thrust and
lots of propellant they also do
something that they previously didn't do
in Kerbal space program they have thrust
vectoring because a lot of people don't
realize that real solid rocket motors
can have thrust vectoring they are
technological items sure they have a
combustion chamber they have a nozzle
and that nozzle can be vectored anyway
I've taken a very unorthodox launch
profile here you notice that I went
straight up the reason is that I
calibrated each of these first two
stages to get me exactly into a nice
circular orbit so I go straight up and
then when I get straight up I turn the
thing across and pointed 90 degrees well
okay wait for thrust vectoring to kick
in and yeah more or less this thing has
exactly the amount of Delta V that I
should need to get into a circular orbit
so one thing you'll notice here that is
that I will try to get my time to Apogee
to hang around zero I'm essentially
trying to control my my sync rate or my
vertical speed so that it remains very
close to zero and there you go look
beautiful in 87 and just over 100
kilometers that's not bad for having two
rocket motors that I have zero control
over or rather all the control comes
from deciding the Delta V of each stage
so this next stage for the translunar
injection is eighty eight hundred and
sixty-six meters per second so to do
this I'm just gonna put 866 meters per
second into my
maneuver annoyed and now I'm just gonna
adjust the time that the manoeuvre
happens so that it puts me as close to
the moon as possible this is the new
manoeuvre planner that was added a few
versions ago and it's very very helpful
I'm gonna say I mean there are
significant challenges of navigating a
spacecraft using solid rocket motors in
real life in particular you know you can
actually get the level of precision that
I'm getting in Kerbal space program
because we don't know the exact Delta V
typically you've got a margin of error
of a few percent and in this particular
case a difference of a few percent could
send you off into deep space and you
would miss things completely in the case
of New Horizons it's solid rock at final
stage actually over performs and they
had to spend some time using their
liquid propellant engines to slow the
spacecraft down so it would actually
make its Jupiter encounter at the right
time so the next challenge is getting
into orbit around the moon now you can
just fire your engines in sequence but I
really want to get the perigee as close
to the surface of the moon as possible
so I came up with this two-stage
maneuver where I make one maneuver that
actually puts me closer and then the
second one which breaks me into a sort
of elliptical orbit that passes close to
the surface it turns out that I've
actually get three-stage correction burn
so I can use but I've only I'm only
gonna need two of them
you know there was a spare one there if
I needed it I will respect the whole
thing but I didn't want to take it out
obviously because the Delta V of every
previous stage depends upon the mass of
the upper stage it's one of these things
where you realize you know if you cut
things down you then have to rebalance
every stage so now I'm in your name
kilometres above the surface I don't
want to slow the heck down and I'm going
579 now I could orbit around one more
time but I decide that I'm just gonna go
straight for the landing here so
actually what I do is I you just dump
these extra stages and now I'm gonna go
for the landing so for the landing I
have more Delta V for this first burn
than I have orbital velocity so if I
just burn that it would mean that I
would start going backwards so what I
instead
is point downwards at a 30-degree angle
and because of cosine losses my Delta V
decreases faster than my surface
velocity and so at some point the
surface velocity and the Delta V display
on the Left get very close and then I
yeah tell it to point retrograde and now
I'm actually slowing down safe and the
knowledge that I will reach pretty much
zero velocity over the surface at some
reasonable altitude now if I had too
much Delta V I could end up just
bubbling straight into the surface I
should also point out that this engine I
set it up to use only thirty percent
thrust because I wanted to be able to
think my way through this situation do
the math in my head so I'm close enough
to the surface now that you can actually
see rocks it's there's several rockets
here that I could use for the landing
I'm just gonna use these little these
are the new ones these are the might
motors by the way there are one point
sorry no there are point six five meter
engines and there are a rather nice so
there are strong on the outside for the
simple reason that when I hit the stage
command it will separate the D couplers
and they will pop off so I wait until my
velocity gets down to zero and then I
will dish I will detach them and then I
will have controlled my descent you see
so you're mounting them in pairs on the
outside and dropping them means I can
control and finally a trick from the
soviet lunar landing program using the
rocket motors the SEPA tries to push
myself onto the ground and make sure i
don't bounce around too much and look at
that I got on I actually had several
stages worth of landing Rockets still to
use that I could have you know iterated
on but got to the surface planted the
flag for posterity we choose to go to
the moon not because it's easy but
because there's great potential for
explosions yeah I decided no that I've
got all these extra stages so I'm gonna
try and get home more or less without
changing direction just so happens that
I landed pretty much on the side of the
Moon which is retrograde so I can just
keep to see
orientation the spacecraft will
eventually get me home I mean clearly I
could have built a much smaller vehicle
and got all the way home these small
engines aren't actually that efficient
but I kind of wanted to have lots of
options at every stage to make sure that
if something went wrong I had
contingencies to make sure that if I you
know if I needed to make course
corrections there were ways to do it
having lots of small rockets makes the
thing a lot more controllable indeed
you're one of the earliest written down
plans for a rocket to the moon I
actually used clusters of black-powder
rockets and they would have these big
hexagonal bases and they would fire them
by pulling strings I think it is kinda
ridiculous but well and they would of
course do their navigation by hand and
once they figured out they would point
the rocket in the correct direction and
then fire as many mortars as they need
its plans like that that make me
realized that real life can be way more
Kerbal than Kerbal space program oh yeah
all I'm doing here in this manoeuvre is
bringing my my descent rate was gonna be
too fast I was gonna plunge too deep
through the atmosphere too quickly so
I'm firing the engine at 90 degrees to
lift my orbit up so that I will now fall
through the atmosphere and glide to his
safe descent huh and now I can get back
to actually writing a bit cheney's
rockets and your other things you know I
I don't know I just felt that I needed
to post a Kerbal space program video to
break the writer's block maybe that's
what it is I don't know I I look forward
to coming up with some more science or
history or rockets or God there's so
many things I want to talk about
sometimes the hard part is just figuring
out what and also making sure that I do
it at a level of quality that makes me
happy because I don't like to cut
corners I do like to play Kerbal space
program I guess I like to procrastinate
a lot sometimes that's the big problem I
mean maybe I should do a video on solid
rocket motors but boy that is a an
interesting subject did you know that
the first solid rocket motor that is
matched a modern design of
and binder was Jack Parsons Jack Parsons
he basically asked fall in a regular
mixture of well explosives and
stabilizer and bang he had a solid
rocket motor well I mean it didn't go
bang it burned yeah Jack Parsons the
same guy that founded JPL and founded
Aerojet Rocketdyne and also had our
stroke Rolly as a spiritual advisor so
yeah that was an interesting character
if I do say so myself so with the
conclusion of this successful challenge
mission thanks everyone for tuning in
and staying put and watching this I
always appreciate your company I will be
back with more science next time I'm
Scott Manley lie safe
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