spinning satellites

[atxcple]

watching a old movis about silicon valley and Fairchild. noticed something i see alot in old launch footage from mercury era launches.. Is it me or does it always look like the satellite on the nose of the mercury rockets look to be spinning before takeoff. if so why would the have them spinning?

 

[dlazarus6660]

There was time when I could explain this to you but now I just can't remember.

 

[burnout]

It compensates for thrust imbalances when the motors a started like a gyroscope.
https://history.nasa.gov/sputnik/expinfo.html

 

[bobby_hamill]

Explorer 1 being launched and showing the payload starting to spin

https://www.youtube.com/watch?v=vyUQ9JC8QgQ

Bobby

 

[burnout]

Explorer 1 being launched and showing the payload starting to spin

https://www.youtube.com/watch?v=vyUQ9JC8QgQ

Bobby

That is a very cool video. Thanks.
Interesting to see the tech mark the analogue gauge with a pen or the computer at 12:19 that looks straight out of a buck rogers movie.
It seems like those guys were more blue collar than the rocketeers of today.

 

[bobby_hamill]

check out this video

https://www.youtube.com/watch?v=-r_jfABiKI0

at 40 on the tape the jet vain was reported as being deflected the head man looked out the window then at the panel and said FORGET IT now that is high tech lol !!

Bobby

 

[burnout]

that looked scripted to me,still a great video.

 

[aerostadt]

The Atlas Mercury did not spin. For that matter I think the only rocket that had spinning was the Jupiter-C for the upper 3 stages. The Redstone was the first stage and stages 2, 3, and 4 were composed of small solid rockets (sargent ? solid rocket motors, probably similar to the motor in the Loki Dart) with straight nozzles (unvectored). I am thinking that the guidance was just gravity turning, thus, the upper stages were spun to keep them on course. The 4th stage had just one single motor in the aft-end of the Explorer satellite itself.

 

[sodmeister]

That last clip "Fo geddit " reminded me of an old James Bond movie LOL

Paul T

 

[aerostadt]

I just went back and looked at Peter Alway's "Rockets of the World" and read the write-up for Juno I (Jupiter-C). The write-up states that the guidance section carrying the 3 upper stages used small gas jets to point itself due east. The Redstone provided the altitude, but the small Sergeant rocket motors provided the orbital velocity. The second stage had 11 Sergeant motors, the 3rd stage had three Baby Sergeant motors, and the Explorer I itself had one Baby Sergeant in the base of the satellite. The Sergeant motors had a burn time of about 6.5 seconds and each motor was equivalent to a P 8,000.

 

[atxcple]

makes we wonder if a scale version with a electric motor spinning the "satallite" on top of the nosecone would fly straight

 

[luke strawwalker]

watching a old movis about silicon valley and Fairchild. noticed something i see alot in old launch footage from mercury era launches.. Is it me or does it always look like the satellite on the nose of the mercury rockets look to be spinning before takeoff. if so why would the have them spinning?

Stability...

Spin it like a rifle bullet... the upper stages were solid motor clusters and spinning them kept the thing headed in the right direction despite any thrust imbalances...

Later! OL JR

 

[luke strawwalker]

The Atlas Mercury did not spin. For that matter I think the only rocket that had spinning was the Jupiter-C for the upper 3 stages. The Redstone was the first stage and stages 2, 3, and 4 were composed of small solid rockets (sargent ? solid rocket motors, probably similar to the motor in the Loki Dart) with straight nozzles (unvectored). I am thinking that the guidance was just gravity turning, thus, the upper stages were spun to keep them on course. The 4th stage had just one single motor in the aft-end of the Explorer satellite itself.

Juno (converted Jupiter missile) was spin-stabilized upper stages as well, but they were contained INSIDE a non-spinning fairing, unlike the Jupiter C... so you just couldn't see them... but they did spin.

Course over like half of the Junos blew up too... LOL

Later! OL JR

 

[Delta-IV]

We still spin a lot of the spacecraft we put up, but it is done just prior to separation from the upper stage. Mostly for stablity and also for sun exposure. Better to cook the thing evenly.

 

[mikemech]

IIRC the Honest John army artillery missle spun internally for stability.

Mike

 

[shrox]

How did the stages spin? Was it a motor, or just a pull string and great bearings?

 

[luke strawwalker]

IIRC the Honest John army artillery missle spun internally for stability.

Mike

Honest John, along with many other military rockets, spun for "rifle stability"... HoJo had EXTERNAL spin motors (4) affixed to the aft portion of the bulbous nose which fired up almost immediately after the rocket had left the launcher to "spin up" the rocket... The entire rocket spun, not just the nosecone or any "internal" spinning...

Lance IIRC did the same thing...

Later! OL JR

 

[luke strawwalker]

How did the stages spin? Was it a motor, or just a pull string and great bearings?

electric spin motor and the upper stages were mounted on a spin table-- basically a fancy name for a really big ball bearing or otherwise known as a fancy "lazy susan"... LOL

Most satellites injected into their final transfer trajectories by solid rocket motors are spun up before separation and ignition of the solid motor (kick motor). Usually these motors have no form of nozzle gimbaling or manuevering thrusters for stabilization, so spinning them up provides "passive stability" while the solid motor burns (they burn for pretty short periods of time, so active stabilization isn't really necessary and would deduct from payload capability.

Most of these satellites or deep space probes then deploy "de-spin" counterweights which spool out from the sides of the satellite, after the motor casing is seperated, to minimize the inertial mass that has to be despun. They work basically like a figure skater extending her arms from a fast spin-- the further she extends her arms, the slower she rotates... once the despin counterweights are completely run out to the end of their tethers, they are discarded, flying off in opposite directions. Any remaining spin is usually used to keep the satellite alone passively stable, or can then be completely despun by small maneuvering thruster firings, minimizing propellant usage, which of course is QUITE valuable and restricted on such vehicles...

Later! OL JR

 

[atxcple]

One of the local clubs has a flyer who is testing a scale Honest John using 4 Estes motors in the nose cone to induce the spin

 

[shreadvector]

https://www.youtube.com/watch?v=UZ0WZpwFLcA

 

[atxcple]

makes you wonder how they are going to fix satellites in space now without a capable shuttle replacement

 

[luke strawwalker]

makes you wonder how they are going to fix satellites in space now without a capable shuttle replacement

It's cheaper to launch a new satellite than to repair satellites in orbit (that are malfunctioning). There MAY be a case for refuelling satellites that are otherwise functional but simply have run out of station keeping/pointing propellant and thus are useless-- but that capability and the justification for it still remains to be seen-- that's what the satellite refueling experiment they're conducting now is all about...

The only time the shuttle could really service a satellite and make it a worthwhile proposition was when they had a satellite trapped in a useless orbit due to a staging failure, and the shuttle could attach a new propulsion stage to boost it to the proper orbit. The idea of bringing malfunctioning satellites back to Earth for repair and relaunch was NEVER going to be a worthwhile endeavor...

Even the repairs of the Hubble Space Telescope, the supposed "crown jewel" in the shuttle program, cost SO MUCH in mission costs and in limiting Hubble to an inferior LEO where it was capable of being reached by shuttle (inferior in terms of the mission and observation time-- in LEO there's a huge honkin' planet blocking your view of the cosmos 45 out of every 90 minutes or thereabouts... and the thermal environment is terrible and imposes a lot of challenges on successful telescope design. In fact, it would have been no more expensive and been a lot more capability had, instead of servicing the ONE Hubble we have, to launch MULTIPLE instruments to better SEL-1 or 2 observation orbits, or even GSO. The extra telescopes could have done MUCH more science until they ultimately failed, and would have cost no more than doing repeated servicing missions on the one telescope we have.

So, the retirement of the shuttle's ability to repair satellites or bring them back to Earth is a case of a capability that was never really needed in the first place being put out to pasture.

Later! OL JR

 

[bobby_hamill]

in the last part of the attached video you can see 2 small balls extend out on cables from the spinning satellite and are cut away when the spinning stops


https://www.youtube.com/watch?v=ULTKCAINe5A

Bobby

 

[luke strawwalker]

in the last part of the attached video you can see 2 small balls extend out on cables from the spinning satellite and are cut away when the spinning stops


https://www.youtube.com/watch?v=ULTKCAINe5A

Bobby

Yep, despin counterweights...

Later! OL JR