Strictly Liquidy...

[Carthaginian]

Does anyone else deliberately try to avoid using SRB's in their construction?

I feel that my Program is at its earliest, most basic stage of development... and that some tech should be off-limits.

Anyone else have those kinds of restrictions?

[Nibb31]

SRBs are actually much lower tech than turbopump driven liquid bipropellant rockets. They are closer to chinese firecrackers.

I tend to avoid them because I like to be able to control thrust on my rocket, and I find that liquid engines are usually more efficient and versatile.

Edited August 25, 2012 by Nibb31

[Suzaku]

SRBs were the first rockets and the lowest tech rockets.

[Kosmo-not]

In 0.16, the small SRB has the I_sp to make it worth using. The large SRB is not efficient at all, so I never use it.

In 0.17, the small SRB will probably be nerfed, as solid rocket boosters shouldn't be as efficient as liquid fueled rockets.

[Carthaginian]

None of the early manned programs use SRB's as their launch vehicles.

All the rockets that I can remember being used were liquid fueled, and that makes me want to stick with them.

Also, though the Chinese used 'solid rocket motors'... well, the age of modern rocketry was ushered in by liquid engines.

[bsalis]

I believe that SRBs were not used on early manned rockets mainly because of safety reasons. The big one being that they could not be shut down. Trying to abort a launch during ascent with SRBs still going can't end well... imagine being pulled away by the escape tower while the rocket is chasing you under SRB thrust *shudder*

Also note that the Challenger disaster was due to SRB failure.

Obviously, in the Kerbal Space Program, attitudes to safety are a little different.

[Elios]

yup even the shuttle the plan if any thing went wrong when the SRBs where burning you had to ride it out

[Carthaginian]

I believe that SRBs were not used on early manned rockets mainly because of safety reasons. The big one being that they could not be shut down. Trying to abort a launch during ascent with SRBs still going can't end well... imagine being pulled away by the escape tower while the rocket is chasing you under SRB thrust *shudder*

Also note that the Challenger disaster was due to SRB failure.

Obviously, in the Kerbal Space Program, attitudes to safety are a little different.

I know what caused the loss of Challenger- watching the the accident on TV is one of my earliest memories. That's one of the reasons that I'm so adamant on not using SRB's 'early in the program.' I mean, right now there are no 'automated launches' so everything has to have a Kerbal ride OR a mod present... but a great deal of my program is centered around keeping the pilots alive as long as possible. Most Kerbal players would laugh out loud at the number of parachutes and staging devices on my designs- every rocket has an 'escape stage' which is capable of getting my Kerbal out of harm's way.

Improperly cast solid rocket propellant goes *BOOM*.

Improperly maintained solid rocket boosters go *BOOM*.

Solid rocket engines are like rotary aircraft engines- they are either 'all stop' or 'balls out,' you have no throttle control.

Liquid fuels present their own dangers- but they are easier to abort, which is a big issue when you're still learning.

[Elios]

almost all the early NASA attempts were unmanned same with the USSR at the time

NASA wanted to make almost every thing controlled from the ground but the pilots would have none of it they didnt like the idea of just being along for the ride

all flights that NASA made the assent was computer controlled only re-entry was done by hand with lots of help from the ground

the even shuttle is flown by the computer until final

the whole computer revolution was kicked off by the space race

also most early liquid rockets were the same way all go or stop the SSME was the first throttle-able engine

Edited August 26, 2012 by Elios

[Maxed-Rockets]

I know what caused the loss of Challenger- watching the the accident on TV is one of my earliest memories. That's one of the reasons that I'm so adamant on not using SRB's 'early in the program.' I mean, right now there are no 'automated launches' so everything has to have a Kerbal ride OR a mod present... but a great deal of my program is centered around keeping the pilots alive as long as possible. Most Kerbal players would laugh out loud at the number of parachutes and staging devices on my designs- every rocket has an 'escape stage' which is capable of getting my Kerbal out of harm's way.

Improperly cast solid rocket propellant goes *BOOM*.

Improperly maintained solid rocket boosters go *BOOM*.

Solid rocket engines are like rotary aircraft engines- they are either 'all stop' or 'balls out,' you have no throttle control.

Liquid fuels present their own dangers- but they are easier to abort, which is a big issue when you're still learning.

Although I agree with our suspicion of SRB's as dangerous (they always seem to make my rockets spin) I must correct you on the rotary engines: http://en.wikipedia.org/wiki/Rotary_engine#Rotary_engine_control

Back on topic, SRB's always make my rockets rotate, not a fatal flaw, but certainly enough to make me nervous.

I usually try to condense my staging so that one engine falls off and the second one starts simultaneously for minimum loss of thrust. In the case of a failure on takeoff (the only time I use SRB's) any SRB's will shred my rocket, whereas LFE's would be fine.

[Tommy521]

I generally stick them on ascent stages (not like I'm going to want to have a low speed), more of the upper stages if I want a larger orbit.

[Carthaginian]

I have the same spinning problem, ranging from a mild 'rifling' effect to utter uncontrollably.

I must correct you on the rotary engines: http://en.wikipedia.org/wiki/Rotary_engine#Rotary_engine_control

None of these are really a 'throttle', the article even says so says so; your options for 'throttle' were to 1.) use a blip switch to kill 'fire' to the cylinder, 2.) choke the cylinder by using a sub-optimal fuel-air mix (to varying degrees), 3.) use a 'selective blip' to kill fire to a set number of cylinders while leaving others running. While the net effect is a form of speed control, none of them are really a 'throttle' in the same sense that can be applied to any other form of internal combustion engine. The most telling comment in the article is that none of the methods are regarded as having been particularly safe or reliable, and that intentionally stalling the engine using fuel/air mixture control was the recommended 'throttle' technique.

Perhaps the most accurate way to say it would be 'a rotary is either firing or not firing'- even if the engine as a whole remains in motion.

[Elios]

but back on topic early liquid rockets were as bad as any thing else at the time

watch the first part of "When we left Earth" tons of liquid rockets that never made it off the pad more that blew up in flight

and the early ones also had no throttle it was all or nothing

the SSME was the first one to be designed to run at less then 100% and that was only down to 50%

[BurningSky93]

I have the same spinning problem, ranging from a mild 'rifling' effect to utter uncontrollably.

To everyone complaining about rockets spinning with SRBs, there is a rather simple solution: use more struts

Trust me, it works. Strap the SRBs to each other, strap the sides of the SRBs to the main rocket, strap the noses of the SRBs to the main rocket. Especially the "strap the sides of the SRBs to the main rocket" part. And keep torque and moments in mind. If you put some struts at the bottom of the SRBs, put some at the top too. I've had so many "spinny" rockets corrected by the use of more struts.

[Seret]

Also note that the Challenger disaster was due to SRB failure.

Not because of any technology peculiar to SRBs though. Failure of a gasket in a liquid fueled engine could have similar effects.

[nibula]

i do not use SRB

[Elios]

Not because of any technology peculiar to SRBs though. Failure of a gasket in a liquid fueled engine could have similar effects.

a gasket failure in a liquid fuel engine would of blown up on the pad when some thing goes wrong with liquid engines it goes fast

[SkyHook]

I find SRBs to abe a great fuel saver and a nice boost off the pad. The ability to go 20% throttle with my liquids until I am out of the thick stuff makes a good difference. I used to rely solely on liquid engines to get out of atmosphere! That was the old me though.

[Bluejayek]

I don't tend to use SRB's. Not because of any philosophical objections to them, just that they never fit in with my designs. Also, being able at abort at any stage is really useful, even though I frequently get into trouble anyways when I forget to throttle down before ejecting a stage.

[Shadoworgon]

Also note that the Challenger disaster was due to SRB failure.

In all honesty, i wouldnt call it a "SRB failure" but more or a "failure to listen"

The engineers working on the shuttle told the head people at mission control to not launch because the O-rings on the SRB's were not designed for the low temperatures that day, but mission control didnt agree and launched anyway, and it was the O-ring that failed. On a side note, if the O-ring failed on the opposite side of the booster, there probably wouldnt have been a disaster, because the ring failed pointing at the external fuel tank and cut into it, and broke the attachment point holding the SRB to the tank.

Sorry, this event was an entire chapter to learn in my Aerospace engineering class

yup even the shuttle the plan if any thing went wrong when the SRBs where burning you had to ride it out

and not to point out mistakes, but thats not correct, there is a system to detach the SRBs safely if something went wrong, and actually detonate them once they were a safe distance away, they actually did that with the SRBs for Challenger once the vehicle broke up. http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster#Range_safety_system

and again sorry for the long off topic post, I'm really into this kind of stuff

but back on topic, I just use SRBs on the initial stage, just for the initial 'boost' off the ground to get some momentum

Edited August 26, 2012 by Shadoworgon

[Rickenbacker]

"You don't put people on top of solid rockets" was more or less a rule at NASA in the early years. Personally i avoid them, except as kickers to get the first stage off the ground.

[Seret]

Sorry, this event was an entire chapter to learn in my Aerospace engineering class

I did it in a couple of different mechanical engineering courses. It's become a bit of a ubiquitous case study.

[Vanamonde]

SRBs in the game run for 30 seconds, but a flight to orbit takes 12 minutes or more, and flights to the moons last for days. They might more sense for you guys who are using mods to put small satellites in orbit and that kind of thing, but my feeling is that if my multi-day mission requires SRBs to get off the paid, then it needs a redesign rather than a brief boost. I haven't used them since my initial experiments revealed how quickly they burn out.

[crekit]

I prefer using them because they are more fun and more challenging. I have gotten an orbit with only them I do think, but it's usually a pretty crazy orbit.

[khyron42]

I tend to go "all or nothing" on SRBs. My normal designs don't use them, but I'll sometimes make experimental SRB-only attempts (or SRB-only lower stages.) For small suborbital tests of landers eventually intended for the moons I'll sometimes use solids as the boost stage.

Modern Rocketry got a big help from Robert Goddard, but he improved solid/powder rockets at the same time as he invented liquid ones. de Laval nozzles were needed to make either work well. Liquids have three main design advantages that I know of:

- ease of shutdown.

- burn control by proper fuel mix measurements is adjustable, rather than having to ensure the solid fuel is uniform enough to give the correct burn.

- the fuel tank being separate from the combustion chamber, allowing the tank to be lighter. It only has to withstand fuel pressure, not combustion pressure. This is somewhat offset by the need for fuel pressurization, pumping, and other support equipment.

On the other hand, they are much harder to design well, because they tend to rely on 10 different things all working perfectly, instead of 2 or 3.

Rocketry history has been made time and time again with both types. Many unmanned launchers today use solids at some point in their stages, the shuttle and some proposed manned future launchers use them as first-stage additional boost, and the SpaceShip One & Two designs by Scaled Composites use a hybrid liquid oxidizer/solid fuel rocket for their manned launches. I'd say both can have a place in your KSP program even if you're trying to fly missions in a very non-Kerbal way!

Along the same lines, if you're really serious about launch safety, keep track of your total number of launches and fatal ones. If you can manage fewer than 1 fatal accident per 70 launches, you're doing better than the shuttle did (2 out of 135.)