TCCoA Forums banner

81 - 100 of 125 Posts

·
Super Moderator
Joined
·
11,031 Posts
Here's the awesome one!!

<iframe width="560" height="315" src="https://www.youtube.com/embed/BhMSzC1crr0" frameborder="0" allowfullscreen></iframe>


But I found an even better view. :D

<iframe width="420" height="315" src="https://www.youtube.com/embed/DDF2DQ5rAh0" frameborder="0" allowfullscreen></iframe>

It slewed the gyros too fast, and was not able to correct; those little thrusters didn't move it sideways like that. :)

The gyros pulled it to where they thought "Up" was, but the choice was wrong, likely due to vibrations in the sensors while the engines are firing.

Damn close, tho.

It's funny seeing the thrusters firing; I think the thrusters' programming aren't taking into account the gyro precession effect.

It doesn't fall over till the gyros hit their limit; then it falls over regardless of the thrusters... Just like Sci-Fi, lol.
 

·
Registered
Joined
·
1,147 Posts
Discussion Starter #82
Just watched that first video on another site this morning. Man, that was close.

Hadn't seen the second video you posted. Must have been down right painful for them to see it topple over like that in the last few seconds. Dang! Almost only counts in hand grenades, and horseshoes. I hope the third time is a charm. Reminiscent of the early 60's, this is a special time in space exploration.

Thanks for posting! :)
 

·
Super Moderator
Joined
·
11,031 Posts
That video should really make them proud; they brought a booster to a landing for at least 5 seconds, until it fell over.

"UP" is a very subjective thing; it's really hard to determine under thrust.
 

·
Registered
Joined
·
1,147 Posts
Discussion Starter #84 (Edited)
Groog6 said:
I think the thrusters' programming aren't taking into account the gyro precession effect.
"UP" is a very subjective thing; it's really hard to determine under thrust.

Aerospace technology uses ring laser gyros, and accelerometers which use a differential capacitor to measure changes in gravitational pull. Fundamentally the same as those found in smart phones, and tablets which cause the screen to always flip right side up regardless of how the user moves the device. Etched from silicone there is only microscopic movement of the cantilever beam. Hence, the ring laser gyro does have moving parts with a much smaller amount of movement than its obsolete mechanical counterpart. The silicone-based accelerometer has no moment of inertia. Plus, these electronic devices have a huge amount of weight savings for the rocket.

(Some may be familiar with "Polar" Moment of Inertia if they've ever driven a 911 hard on a track. :D)
 

·
Super Moderator
Joined
·
11,031 Posts
That's a guidance gyro; a stabilization gyro is a hefty beast.

That's what you use to point something when there's no air, and fuel is limited; you pivot it around a gyro.

Three gyros, you get three axes of control.

http://en.wikipedia.org/wiki/Control_moment_gyroscope

Completely different thing from a nav gyro. :)

Since this references the ISS, this is actually on topic!!

I can find references to one, but no pix for SpaceX having control gyros... I'll keep looking.
If they don't use them, my question is "what held it up that long?" the thrusters were firing randomly, and not moving anything when they did.
(I've slo-mo'ed that so many times; it's still awesome.)
 

·
Registered
Joined
·
1,147 Posts
Discussion Starter #87 (Edited)

Thanks for posting that link. That is really cool! I hadn't seen that. I like it :)


Groog6 said:
...a stabilization gyro is a hefty beast.

That's what you use to point something when there's no air, and fuel is limited; you pivot it around a gyro.

Three gyros, you get three axes of control.
Guidence, nav and stabilizing controls of the Falcoln 9 rocket are of digital design. The business end of which, yaw, pitch and roll attitude control, is by means of hydraulic actuators that gimbal the nine main engines for thrust vector control. Cold gas nitrogen reaction control systems are also used for soft touch down.

Keep in mind too that there are distinct differences between gyros, and reaction wheels used on spacecraft.

Gyros provide inertial reference inputs to Attitude and Articulation Control Subsystems AACS computers. If they have any moving parts, they are small and lightweight.

Reaction wheels are fairly massive attitude control devices at the output of AACS computers. Also called momentum wheels. Massive wheels are mounted in three orthogonal axes aboard the spacecraft. They provide a means to trade angular momentum back and forth between spacecraft and wheels. To rotate the vehicle in one direction, you spin up the proper wheel in the opposite direction. To rotate the vehicle back, you slow down the wheel. Excess momentum that builds up in the system due to external torques, caused for example by solar photon pressure or gravity gradient, must be occasionally removed from the system by applying torque to the spacecraft, and allowing the wheels to acquire a desired speed under computer control. This is done during maneuvers called momentum desaturation, (desat), or momentum unload maneuvers.
 

·
Registered
Joined
·
743 Posts
Thanks for posting that link. That is really cool! I hadn't seen that. I like it :)
I've been following it for a couple of years now. There's a crossover point right over the top of my house every once in a while.
 

·
Super Moderator
Joined
·
11,031 Posts
...Guidence, nav and stabilizing controls of the Falcoln 9 rocket are of digital design. The business end of which, yaw, pitch and roll attitude control, is by means of hydraulic actuators that gimbal the nine main engines for thrust vector control. Cold gas nitrogen reaction control systems are also used for soft touch down...
If they can get that much hang time off nitrogen thrusters, that's pretty awesome; that's not a lot of thrust.

I've used gyros a lot, they don't have to be huge. :)

100grams at 100k rpms is a nice source of rotational energy.

Gyros are illegal for model rocketry, for some reason. :D
 

·
Registered
Joined
·
1,147 Posts
Discussion Starter #90
If they can get that much hang time off nitrogen thrusters, that's pretty awesome; that's not a lot of thrust.
The RCS's are used for 3-axis control during coast phases, and single engine burns, (touch downs). They offer no lift capabilities.

The Falcon 9 v1.1 first stage employs an S-Band communications system to transmit performance telemetry throughout the flight, and after stage separation. It is also equipped with a Flight Termination System consisting of two strings of transmitters, receivers and safe and arm devices. The FTS works with C-Band Communications and can be used to terminate the flight in case of any major anomalies.

Fuel for the Merlin 1D main engines use a pyrophoric mixture of Triethylaluminium-Triethylborane as igniter that is injected into the gas generator and combustion chamber to initiate the combustion process that is sustained as liquid oxygen oxidizer, and RP-1 (a highly refined kerosene) flows into the gas generator chamber once turbopumps spin up, initially using high-pressure helium for spin-up. (Try that with your Nizpro's, lol.)

And here's the kicker. The 1D engines have deep throttling capabilities. From 100% all the way down to as little as 30%. I know of no other large rocket with this capability. This manages fuel consumption, and the dynamics of making a soft touch down.
 

·
Registered
Joined
·
743 Posts
The RCS's are used for 3-axis control during coast phases, and single engine burns, (touch downs). They offer no lift capabilities.

The Falcon 9 v1.1 first stage employs an S-Band communications system to transmit performance telemetry throughout the flight, and after stage separation. It is also equipped with a Flight Termination System consisting of two strings of transmitters, receivers and safe and arm devices. The FTS works with C-Band Communications and can be used to terminate the flight in case of any major anomalies.

Fuel for the Merlin 1D main engines use a pyrophoric mixture of Triethylaluminium-Triethylborane as igniter that is injected into the gas generator and combustion chamber to initiate the combustion process that is sustained as liquid oxygen oxidizer, and RP-1 (a highly refined kerosene) flows into the gas generator chamber once turbopumps spin up, initially using high-pressure helium for spin-up. (Try that with your Nizpro's, lol.)

And here's the kicker. The 1D engines have deep throttling capabilities. From 100% all the way down to as little as 30%. I know of no other large rocket with this capability. This manages fuel consumption, and the dynamics of making a soft touch down.
Nerd.
 

·
Voice/Data Guru
Joined
·
7,849 Posts
A word I have heard a lot of the last few months... :D Not a thing wrong with it Race :cool:

 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,727 Posts
Better than ignorance. :)
 

·
Super Moderator
Joined
·
11,031 Posts
Better than ignorance. :)
My thoughts exactly. :)


Thanks, Rush!

I have been looking everywhere for that info; this thread has me interested in high power rocketry again.

You think cars are an expensive hobby... :rolleyes:

I'm sure getting the proper licenses for fuels is not easy, nor cheap.

I wonder if I can model an F1 engine in our modeling software?
Sometimes they encourage employee hobbies...

If I could model it, I could scale it correctly; things have changed in computer simulations since those were designed. :)

A 1/1000 scale F1 cluster would make a nice Rocket Dragster, Until one exploded. :(

The Gas Generators on the F1 engines generated 35,000 horsepower to feed fuel (LO2 and Kerosene) to the main combustion chamber. :)
 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,727 Posts
Anyone been following progress of New Horizons? Less than 10 hours away from closest approach to Pluto. Lots of images already received from the approach, with full color, wide-angle, high-res shots coming soon.

<img src="https://www.nasa.gov/sites/default/files/thumbnails/image/nh-color-pluto-charon.jpg" width="640"/>
 

·
Registered
Joined
·
484 Posts
Anyone been following progress of New Horizons? Less than 10 hours away from closest approach to Pluto. Lots of images already received from the approach, with full color, wide-angle, high-res shots coming soon.

<img src="https://www.nasa.gov/sites/default/files/thumbnails/image/nh-color-pluto-charon.jpg" width="640"/>
I saw a blurb they were releasing pictures today. I can't wait to see. Call me one of the disappointed ones when they downgraded Plutos status.

Maybe we will see Marvin the Martians wrecked spaceship ;)
 

·
WOT Junkie and avid corn burner
Joined
·
3,734 Posts
It's awesome that we can actually see what stuff looks like out there these days. Technology is amazing.
 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,727 Posts
Call me one of the disappointed ones when they downgraded Plutos status.
Well... it is pretty doggone small...

<img src="https://timedotcom.files.wordpress.com/2015/07/nh-pluto-charon-earth-size.jpg" width="400"/>
 
81 - 100 of 125 Posts
Top