soriddo roketto busuta do, the way of the SRB

[kermand]

I have been starting a new carreer campaign, and had much fun using only SRBs for my first stage, and sometimes for my second stage too. I realized it was dirt cheap, that launches required less involvement (no more throttling down while monitoring the TWR, because, hey, you just can't). So far, all my satellites, probes, all my manned Kerpollo program has been put into orbit with clusters of SRBs instead of the usual mainsail + alpha expensive first stage. It works. And it's cheap.

The downside is you can't expect to have a neat 75.000m by 75.000m orbit in the end. More like 150.000 by 180.000. But i found this to be no big deal for any mission so far inside the Kerbin system.

The reason i am sharing this is i would like to turn this art into a science. So far i have been setting my throttle ratio at launch time, amount of fuel and inclination on the launch pad by eyeballing and trial error approach. Have anyone used this approach and come with a way to make succesful launches repeatable and predictable ?

[theJesuit]

Is soriddo roketto busuta the tagine for your agency?  At first glance it sounded like an order of Kerbal ninja monks.

Can't help otherwise.  I find SRBs, although cheap, are heavier than the LFO tank and engine equivalents, and the launchpads have a limit on mass rather than price :!

Peace.

[Harry Rhodan]

6 hours ago, kermand said:

(no more throttling down while monitoring the TWR, because, hey, you just can't).

Unless you have a horribly overpowered craft you also wouldn't (or shouldn't) reduce the thrust on liquid engines.

Edited April 25, 2017 by Harry Rhodan

[Streetwind]

I too like myself some SRBs. I also like to employ the obscure little Variable Thrust Limiter plugin. In real life, a solid motor's thrust is not always constant - the factory can manufacture it with a pre-defined thrust profile that's practically baked into the grain. This plugin lets you do the same in the VAB, in a way. The simple interpolation isn't perfect, but it's definitely a big improvement.

Edited April 25, 2017 by Streetwind

[kermand]

13 minutes ago, Harry Rhodan said:

Unless you have a horribly overpowered craft you also wouldn't (or shouldn't) reduce the thrust on liquid engines.

I was taught otherwise, somewhere else in this forum. Keep the TWR to 1.5 while letting gravity and drag turn the ship, all the way and then reduce even more to get a beautiful, round orbit. And it works incredibly well. The only problem is it keeps you busy throttling down.

Edited April 25, 2017 by kermand
spell miss

[Streetwind]

1 minute ago, kermand said:

I was tought otherwise, somewhere else in this forum. Keep the TWR to 1.5 while letting gravity and drag turn the ship, all the way and then reduce even more to get a beautiful, round orbit. And it works incredibly well. The only problem is it keeps you busy throttling down.

That was true in versions .90 and older, before they completely replaced the aerodynamics model. Nowadays, aerodynamic losses are insignificantly small for normal-shaped rockets even if you are on fire going up.

That said, if your ascent profile works for you, then that's okay. High TWR is more difficult to fly, because it's hard to steer when your vessel really bites into the air.

[Harry Rhodan]

5 hours ago, kermand said:

I was taught otherwise, somewhere else in this forum. Keep the TWR to 1.5 while letting gravity and drag turn the ship, all the way and then reduce even more to get a beautiful, round orbit. And it works incredibly well. The only problem is it keeps you busy throttling down.

The idea is to launch with a TWR of around 1.5, not to keep it at that value during ascend.

[Urses]

I think the only real disadventage for SRB is they lack of gimbal. But if we include the Separatrons here, we can handle it good with reactionwheels.

In the atmo you can use steerable fins (like Tail Fins) and Positioning the roket in the right way, 5° to east and let it go.

Or i use drag as a turnhelper, some fins more on east side of rocket and go.

SRB's have many usable options, and if you use tweackables you have a realy fine method to dig a lill more DV out of the rocket. Build sharp on weightedge tape some SRB's on and tweack a lill from SolidFuel down. This way i have more fuel in upperstages and can sometimes fullfill 2-3 sat contracts with one launch and one sat.

Funny Kabooms 

Urses 

Edited April 25, 2017 by Urses

[Cunjo Carl]

I'm a huge SRB fan, and while they're ultimately less well rounded than liquid fuel engines, they're obliquely well suited for all sorts of fun things.

The Flea has the best cost per thrust in the game, and clusters of them can hurl you off the launch and up to your optimum lift velocity cheaply and easily. Otherwise, a standard liquid fueled rocket would either have to
A: Waste a lot of time and fuel accelerating to the optimum velocity, or
B: Bring along more liquid fueled engines to drive up the TWR, increasing cost and dry mass.

The Hammer has a phenomenal TWR when compared to the liquid fueled engines, being equivalent to somewhere around 35-40 depending on how you want to run the numbers. This TWR makes for some fantastic deltaV when you need a high thrust on a small payload, like on the middle stage of a Eve launch, or the first stage of a Tylo launch.

I'm sure the BACC has it's uses

And the Kickback is a mainstay cost efficient launchers, boasting the KSP's best cost per impulse (besides air breathers).

My start in KSP was through strapping bigger and bigger clusters of SRBs together, and while I knew a mainsail was the normal launch solution, I was having too much fun to care! Here's my first craft that made it to the Mun and back... It was before I knew about saving/loading so the trip there was frought with peril, and the trip back was nothing short of miraculous. That trip probably shouldn't have been a success, but I made it on that stack of boom! And, I've been hooked on KSP (and finding fun uses for the SRBs) ever since.

For some somewhat more incredible uses of SRBs, I'll just leave this little link here: https://youtu.be/aKa5T0EZRxY
It's @hazard-ish being @hazard-ish.

[Ten Key]

I love solid rockets. 

 

 

As long as we're sharing videos, this one's fun.

[DoctorDavinci]

2 hours ago, Cunjo Carl said:

I've been hooked on KSP (and finding fun uses for the SRBs) ever since.

Here's one for you 

 

[Cunjo Carl]

5 minutes ago, DoctorDavinci said:

Here's one for you 

That one's an old favorite of mine! Looking forward to the next Great Canadian Challenge, btw.... Come to mention it, the Great Canadian Domino challenge should update well now single part wings fall over in a less awesome realistic way.

[suicidejunkie]

Making a high velocity launchpad out of a brick of SRBs is a classic.

I like giving my rockets a starting TWR of 1.0, and igniting them at the speed of sound.

 

If you want precision maneuvers with SRBs, you'll need to include separators so you can jettison the still-thrusting booster at the right time and get large but arbitrary amounts of dV.

Having a 24-pack of separatrons that fire in pairs for balance can allow you to make small, controlled correction burns as well.

[Starman4308]

There's Stratenblitz75's Youtube channel, which has a lot of all-SRB missions (Eeloo, RSS Moon, etc). For my own craft, my first stages are almost always liquid (kerolox/methalox) cores with solid boosters attached radially, so as to give those expensive liquid engines an extra kick up during the first 30-60 seconds of launch.

[Snark]

On 4/24/2017 at 2:34 PM, kermand said:

Have anyone used this approach and come with a way to make succesful launches repeatable and predictable ?

Well, you may find this challenge thread to be an interesting read. 

Here's a very simple example:

Or, if you want to get totally silly with it, spaceplane-style. 

If you go to the "awards" section at the end of the OP, there are various "entry" links that will take you straight to various people's implementations of fire-and-forget SRB-to-orbit vehicles.

Both of the above examples (like everything in that thread) are totally fire-and-forget.  You launch it to the pad (or runway), hit the space bar to do the initial setting, and then just sit back and sip your coffee as you watch it fly itself to orbit.  No autopilot (e.g. no MechJeb or anything)-- the only automation there consists of some timers.

 

On 4/24/2017 at 3:03 PM, theJesuit said:

Is soriddo roketto busuta the tagine for your agency?

It's a rendition of how a Japanese person might pronounce "solid rocket booster."  And it's actually pretty close to the real Japanese term, 固体ロケットブースタ, which transliterates as "kotai roketto buusuta".  They've got a perfectly good native word for "solid", kotai, so they don't need to borrow that one from English.

[kermand]

5 hours ago, Snark said:

Well, you may find this challenge thread to be an interesting read. 

Sweet! Thank you.

5 hours ago, Snark said:

It's a rendition of how a Japanese person might pronounce "solid rocket booster."  And it's actually pretty close to the real Japanese term, 固体ロケットブースタ, which transliterates as "kotai roketto buusuta".  They've got a perfectly good native word for "solid", kotai, so they don't need to borrow that one from English.

exactly. i used "soriddo" because more people can get it than 固体. the  "do" stands for "way of" as in kendo, bushido, judo... so, ソリッド・ロケット・ブースタ道, because sitting on a pile of explosives you wont be able to turn off or control whatsoever in the hope it will get you to space is more than just technology. It's a way of life.

one could also get creative and write it 固体補助推進装置道, which would be quite badass writen on a board at the entrance of the space center.