Question for spaceflight geeks...

[Typhoon1244]

...er, I mean "aficionados."

I got to thinking today about Apollo XIII's loss of a second-stage engine during their climb, and I started wondering:

Does anybody know whether or not the old Saturn V moon rockets were capable of making the initial climb if they lost one of those gigantic first-stage "F1" engines? Or would the loss of a motor have meant disaster? (The level of reliability that must have been demanded from those things is just staggering to me!)

 

[Timebuilder]

Wow. That's a tough one. Wish I'd asked one of those engineers when I had the chance.

I think it is reasonable to see this as a function of when the engine would fail. Close to shutdown and separation? Probably no biggie. Halfway through the burn? Could be a problem. I'd have to see the specs on the thrust made by the remaining engines vs the thrust that was required to accellerate the first stage to the speed envelope that permitted the second stage to reach escape velocity.

Maybe someone more "geeky" has the precise answer.

 

[sstearns2]

.....

Rocket engines are normally used for control as well as thrust, so loosing a first stage engine would present a major control problem unless it was the center engine. Even if they could control it they would probably not get the impulse they needed due to the longer burn that would be required to burn the fuel with only four engines. I'm sure they try the champagne cork trick and abort.

Scott

 

[katanabob]

It would depend on how late it happened as to whether the required impulse could be produced by a longer burn of the remaining engines. Later is better; there are charts floating around somewhere that would be able to tell you just how early you could lose one and continue.

 

[Timebuilder]

The steering is an interesting question. Does anyone know how the steering was controlled?

 

[Big Duke Six]

Shuttle Wallpaper

OK, not to hijack the thread here, but while I may have the attention of those who may know I'd like to ask:

How in the heck did they get the photo of the Shuttle Columbia in orbit that you see for sale in Sporty's as a huge wallpaper mural?

Great shot, but all I could think of was that they must have used a satellite. The thing is it just doesn't seem like a satellite could focus that close (or maybe it wasn't that close after all) or that they would tie up a satellite just to take a pic of the Shuttle.

Anyone?

 

[Typhoon1244]

The steering is an interesting question. Does anyone know how the steering was controlled?

From NASA's Apollo IX press kit, 2/23/69
The S-1C stage provides first boost of the Saturn V launch vehicle to an altitude of 37 nautical miles...and provides acceleration to increase the vehicle's velocity to 9,095 feet per second (2,402 m/sec, 5,385 knots, 6,201 mph).

Normal propellant flow rate to the five F-1 engines is 29,522 pounds per second. Four of the engines are mounted on a ring, each 90 degrees from its neighbor. These four are gimabled to control the rocket's direction of flight. The fifth engine is mounted rigidly in the center. [Emphasis added]

I have not yet found any reference to how S-1C engine failures were handled.

Aren't those numbers just amazing? Twenty-nine grand per second? Wow!

 

[Timebuilder]

Wow. That's a lot of everything. Amazing that we were able to do this with the rather unsophisticated computers of the sixties. People still carried sliderules!!!

I suspected the gimbal mounting, but I wasn't sure. Hard to see that stuff when you walk under the Saturn on display over at the cape.

 

[Typhoon1244]

A bit more on steering, from Moon Launch! by Charles Benson and William Faherty:

Two hydraulic actuators swiveled each engine in response to signals from the flight control computer located in the instrument unit.

The instrument unit was located between the S-IVB propellant tanks and the Lunar Module shroud. It contained radar altimeters, accelerometers, recorders, computers...and a "remote digital sub-multiplexer."

(I may have one of those in my car...)

 

[LJDRVR]

I dug through all of my apollo related material, I couldn't find the answer. I did however, happen upon some interesting stuff in one of Michael Collin's books.

Apparently the biggest design issue with the Rocketdyne F-1 engine was combustion instability. Engineers had to be certain that the engine would continue to run even if a "hiccup" occured in the propellant/oxider delivery. (55,000 horsepower turbopumps!) To lay the issue to rest, engineers spent 18 months modifying the design of the spray bar. (Amount/angle/placement of nozzles) much of this work was trial and error, but the main tools used to collect data were...get this... BOMBS. Small, nylon-encased bombs, some as small as 50 grams were placed inside the combustion chamber. The engine would ignite and stabilize at full power before the nylon burned through and the bomb exploded. Eventually, they were able to set of all manner of explosions, with no more than a 1/10 of a second interuption of power.

If I recall correctly, the first thing the crew heard was at T-12, when you could both feel and hear the turbopumps spinup. These could empty an olympic sized pool in 2.5 seconds. Then the F-1's were ignited at T-8 seconds, building up to full power several seconds before zero was reached. Only if all engine parameters were nominal would the large, multi-ton holdown clamps realease the Saturn IV at "zero".

Well, okay. the geek annunciator light has illuminated! But I believe the Apollo program was one of the defining moments of the human race. I was two years old in 1969, and it's one of the very first things I remember.

 

[banned username 2]

Good Stuff guys, keep it coming!

If you haven't seem the mini-series "From the Earth to the Moon" narrated by Tom Hanks, I HIGHLY recommend it... I think it is 6 VHS tapes long, even my wife loved it!

 

[Big Duke Six]

Sure...

This would all be great guys, IF we had actually gone to the Moon....

Seriously though, those numbers are impressive, almost beyond comprehension. Does anyone know what they did for electrical power to run those pumps? Seems like you couldn't carry enough batteries, but maybe they did. They had to have generators of some kind huh?

 

[Typhoon1244]

From the Earth to the Moon...good stuff, man! One of the most interesting epsiodes goes into the design of the Lunar Module. Gives you some insight into how high-level engineering works. "Why do they need seats?"

My favorite scene, though, involved Pete Conrad--played by Paul McCrane. (You know, "Dr. Romano" on E.R. He got squashed by a JetRanger last week.) Conrad didn't put a whole lot of energy into maintaining this image of infallibility the public expected from astronauts. A fifth-grade class was doing a tour of one of the test areas while Conrad was having trouble with some experimental equipment. Right in front of the kids, Conrad slaps the top of the drill, steps back and declares "g_d_amnit, this co_ksucker's really starting to piss me off!"

Gotta love it...

 

[sstearns2]

The turbopumps are powered by the rockets fuel and oxidzer. Basically a turbine engine hooked to the pump, except you don't need the compressor section. Imagine an F-16 engine at full burner running a pump! Serious Sh!t.

Scott

 

[Big Duke Six]

Thanks sstearns

That makes sense. I am having a hard time coming to grips with the "can empty an olympic-sized swimming pool in 2.5 seconds" part. Holy crap. How much fuel can a Saturn V carry?

 

[Typhoon1244]

How much fuel can a Saturn V carry?

First stage:
LOX: 3,307,855 lbs. (346,372 gal.)
RP-1 (kerosene): 1,426,069 lbs. (212,846 gal.)
Total: 4,733,924 lbs. (559,218 gal.)

Second stage:
LOX: 821,022 lbs. (85,973 gal.)
LH: 158,221 lbs. (282,555 gal.)
Total: 979,243 lbs. (368,528 gal.)

Third stage:
LOX: 192,023 lbs. (20,107 gal.)
LH: 43,500 lbs. (77,680 gal.)
Total: 235,523 lbs. (97,787 gal.)

GRAND TOTAL ALL FUELS: 5,948,690 lbs. (1,025,533 gal.)

Apollo XI gross weight at main engine start: 6,484,280 lbs.

(Does that answer your question? )

 

[saabcaptain]

While I don't have access to the in orbit picture of the Shuttle Columbia, it was quite common early in the program for it to be photographed from newly released satellites and the pictures often were wonderful. I also know some great shots were taken when testing the MMU, a manned manuevering unit, or "backpack" that allowed untethered EVAs. I think the testing for this was done with Challenger so I suspect the photo you see is from a satellite of Columbia.

I will find a link to it, but you guys should see this video I found of the entire ascent of the shuttle from the vantage of a camera mounted to the shuttle window looking *back* at the astronauts. Amazing stuff to see the SRBs light and everything just blurs. Amazing.

As for the F1 on the Saturn I don't know the answer but most of these first stage engines do gimble and I don't think there is a problem with steering should any one of them fail... but if one engine failed early enough orbit may not have been possible. The jury is still out on that one.

 

[Typhoon1244]

By the way, that means the first stage burned up its fuel supply in two minutes and forty-point-four seconds.

 

[Blue Dude]

Good Stuff guys, keep it coming!

If you haven't seem the mini-series "From the Earth to the Moon" narrated by Tom Hanks, I HIGHLY recommend it... I think it is 6 VHS tapes long, even my wife loved it!

6 VHS tapes? Blasphemy! Get the DVD set. It's expensive (about $100) but it was one of the first - and one of the best - DVD purchases I made. Absolutely breathtaking. And for some strange reason I still can't define, some parts never fail to bring a lump to my throat. Not the mushy moments (there are a few), but the triumph-over-adversity ones. Hard to explain. And you'll never feel prouder to be an American - in the real sense, not the faux, flag-waving, campaign stop sense - than you will be seeing what we can achieve given the will to do so.

My wife (!!!) and I have watched the set together three or four times now. Then gone and visited the cape again. If you knew what a non-geek my wife is, you'd appreciate the victory inherent there. Go get the DVD's. Now.

 

[Big Duke Six]

Yikes

Typhoon wrote:
By the way, that means the first stage burned up its fuel supply in two minutes and forty-point-four seconds.

And I thought a T-38 in blower was bad! That's just awesome power. Lifting 6.4 million pounds straight up? Unreal!

Aha, the MMU theory sounds the most plausible. The photo was of the Columbia (you should be able to see it if you visit Sporty's website) but did they carry or test MMU's on Columbia? I'm thinking of getting one of the wallpapers just for the sentimental value! I've got the perfect wall in my basement, just hope my wife agrees!!