Space or Nothing

General and casual chat about anything.

Moderator: Moderators

Aquaman33
Rocket Crew
Rocket Crew
Posts: 234
Joined: Tue Jul 03, 2018 6:12 pm

Space or Nothing

Postby Aquaman33 » Tue Jul 23, 2019 9:45 pm

A wonderfully produced video that sums up the highs and lows of rocketry really nicely.

Emotional stuff.



Well worth a watch.

User avatar
SpaceManMat
Astronaut
Astronaut
Posts: 2201
Joined: Mon Dec 15, 2008 9:56 pm
Location: Brisbane

Re: Space or Nothing

Postby SpaceManMat » Wed Jul 24, 2019 8:44 pm

Great video, great rocket. 8)
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

drew
Southern fried goodness
Southern fried goodness
Posts: 1016
Joined: Sat Aug 01, 2009 10:20 pm
Location: Perth

Re: Space or Nothing

Postby drew » Thu Jul 25, 2019 10:25 am

Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

Aquaman33
Rocket Crew
Rocket Crew
Posts: 234
Joined: Tue Jul 03, 2018 6:12 pm

Re: Space or Nothing

Postby Aquaman33 » Thu Jul 25, 2019 1:50 pm

Excuse my ignorance, but once you get above the Karmin Line does it get easier to gain more altitude because the atmosphere is thinner?

At what height do rockets escape earth's gravitational pull and not fall back to earth?

I notice these students made it to about 103km, which is a great achievement, but Low Earth Orbit satellites float around at 180km. So still a long way to go to put a satellite in space.

strud
Engineer
Engineer
Posts: 977
Joined: Thu Oct 02, 2008 7:37 am
Location: Central Tablelands, NSW

Re: Space or Nothing

Postby strud » Thu Jul 25, 2019 2:57 pm

A few things I noticed from this video :

- Awesome lab the rocketry society/club has there
- Culture with the group was great, although on the first launch it was bedlam ! Not too hard to tell this was a Southern Californian group without even knowing where they were from :-)
- They were strong enough to learn from the massive loss/failure of the previous attempt which essentially made them able to succeed on the most recent attempt
- Those leading edges of the fins !!!! whoa. Not sure at what altitude they started pulling apart but that must have hurt their altitude a lot
- great job all round really, this will setup those students very well for the real world of engineering

Aquaman33
Rocket Crew
Rocket Crew
Posts: 234
Joined: Tue Jul 03, 2018 6:12 pm

Re: Space or Nothing

Postby Aquaman33 » Thu Jul 25, 2019 3:48 pm

strud wrote:- They were strong enough to learn from the massive loss/failure of the previous attempt which essentially made them able to succeed on the most recent attempt


The atmosphere when that thing was launched prematurely was difficult to watch. Brilliantly captured.

User avatar
OverTheTop
It's only money...
It's only money...
Posts: 2821
Joined: Sat Jul 21, 2007 2:20 pm
Location: Melbourne, Australia

Re: Space or Nothing

Postby OverTheTop » Thu Jul 25, 2019 4:53 pm

but once you get above the Karmin Line does it get easier to gain more altitude because the atmosphere is thinner?

The Karman line is really just a notion of where we consider space to start. It is only 100km, but it is uphill all the way! There is nothing especially special about it. When launching the air density falls off as the height goes up. Here are some details on a pretty good approximation of the real atmosphere: https://en.wikipedia.org/wiki/Internati ... Atmosphere

It is generally said in the HPR community if you can push through 50k' then you are largely out of any pesky atmosphere. Unfortunately there is still gravity to work against. At lease there are no dynamic forces and aeroheating to contend with.


At what height do rockets escape earth's gravitational pull and not fall back to earth?

A long way. Gravity works over exceptionally long distances. Even interstellar distances, measured in light years. A better question to ask might be how high do we need to go for Earth's gravity to be insignificant. Again that depends on where the sun or moon is relative to Earth. Or where our solar system is relative to the other systems in our galaxy. There will be a distance away from Earth where we have more force due to the sun, or due to the moon if we head in that direction. There is a tipping point where the forces balance between whichever two bodies you are dealing with.

Fact: The ISS experiences around 93% of the gravity we have here on Earth.

In order to not fall back to Earth you need to be traveling horizontally. That is what keeps you off the ground. So you need to achieve a suitable height to get out of the atmosphere ("no" air resistance), but then you need horizontal speed to keep orbiting. Think about throwing a ball horizontally. It curves down to the ground. Now throw it faster, and it takes longer to reach the ground because the curve is less. Now throw the ball so hard that it goes out and falls at the same rate that the ground is curving away from underneath it. It has just achieved orbit. If there is no air resistance it will eventually come and hit you in the back of the head!

Fact: The quickest way to orbit an object when there is no atmosphere on the planet is to launch mostly horizontally.

You will see most rocket launches take off vertically and then do a gravity turn, eventually becoming horizontal. Now you know why :)

Fact: The ISS is falling, but because everything on it is also falling it looks like no gravity is acting on it. It is in freefall. It is technically called a "microgravity" environment.

Also consider that you can in fact orbit in the atmosphere. You just need to keep the thrusters going to balance the air drag. That is what many satellites are capable of nowadays. The GOCE mission was a great success story that used that technique, and a great piece of engineering:
GOCE.jpg
GOCE.jpg (14.76 KiB) Viewed 379 times

https://en.wikipedia.org/wiki/Gravity_F ... n_Explorer
TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

Aquaman33
Rocket Crew
Rocket Crew
Posts: 234
Joined: Tue Jul 03, 2018 6:12 pm

Re: Space or Nothing

Postby Aquaman33 » Fri Jul 26, 2019 10:06 am

Thanks OTT.

All very interesting.

I like your fun facts.


Return to “How's the Weather..?”

Who is online

Users browsing this forum: No registered users and 3 guests