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Day 173 - Oobleck (Cornstarch and Water)
10th April 2016
Location:Whalan Reserve, NSW, Australia
Conditions:calm, mostly clear
Team Members at Event:GK, Paul K
We have had a number of requests now to try
( aka Magic Mud / Slime / Cornstarch & Water). This is what's also known as a
Non-Newtonian liquid. It has the unusual property that when you apply pressure to it its
viscosity significantly increases and when you remove that pressure it becomes liquid
For this test we used our smaller Axion III rocket as
we didn't want to have to make up a great deal of Oobleck. For
the first flight we made it a little thicker and it took quite a
while to pour into the rocket. I think we ended pouring only
about 600mL into it.
2Kg of Cornstarch
Mixing is slow
Pouring is also slow
Waiting for Oobleck to settle
Mmmmm ... tasty
Ready to go
We also used our old launcher for this as we knew it was
going to get really messy. The rocket was pressurised to 120psi
and we launched. The rocket popped up a little out of
the launcher and sat back down on the pad with the guide rail
holding it facing up.. We suspect it was just the pressure in the air
hose that allowed it to separate. The rocket then proceeded to
ooze out the Oobleck for the next 12 seconds. You could see the
level dropping in the rocket. When it was sufficiently low the
rocket sputtered and then took off. It looked very much like an
air only launch at that point. The rocket didn't go very high and although the
parachute deployed right around apogee there just wasn't enough
time for it to fully inflate. But the rocket landed safely
sideways without damage.
We made up some more Oobleck with a somewhat more runny
consistency but still exhibiting the right properties. We again
launched the rocket at 120psi only for the rocket to again
repeat what it did last time. The rocket just popped out of the
launcher and sat there oozing the Oobleck. and then 1:20 minutes
later it launched by itself. Again there was not enough time for
the parachute to fully inflate, but because the rocket did not
fall from a great height it survived without damage.
What was interesting that after the rocket had landed there
were a couple of sizable lumps of dried Oobleck in the rocket.
This would have added considerable weight to the rocket as well.
The air must have made its way past the remainder of the Oobleck
still in the rocket.
For the third attempt we made it even more runny and added a
little food colouring. Had we added a couple of eggs we could
have had a nice cake..We debated whether to set the delay to
one second, but there was a chance the rocket might go better
this time so we left it set at two seconds. Nope, the rocket
repeated what it did last time With more Oobleck in it
this time the rocket took 1:28 minutes before it launched itself
and again not very high. This time the nosecone hit first and bucked
the top bottle.
Launching at 120psi
More runny consistency
Not going anywhere fast
Someone needs to clean this
... and this too!
You can't use a non-Newtonian liquid in a water rocket and
expect it to behave itself. Though you have to wonder if this
could be used as a launcher-less launcher. You simply pour some
Oobleck into the rocket and then just quick fill it with water
and air through a thin tube? ... Now we need to go wash
everything off. At least the cornstarch cleans up easily with
We also flew a couple of more flights today related to the
experiment from Day 172 so the detail of those are covered in
the day 172 report..