dandrestor

I reverted to stock and the problem is gone. It was probably one of the mods. Now all I have to see is which one

Thanks to everybody who answered. I understand that there are probably no clear rules, and having researched a little the notion of specific impulse, I realized that the choice of fuel is also irrelevant (Isp is fuel-independent, duh). I disagree that a newbie should be playing with stock parts. First of all, even with stock parts, the same question would still apply. While playing with stock parts might allow somebody to get a 'feel' for what's going on, I believe it would offer no further understanding beyond simple intuition, which is what I am looking for here. PS: can somebody tell me how I change the thread to "Answered"? I'm a forum newbie too.

Excellent write-up, thanks!

Beautiful! Thank you very much.

Hello! After installing a few parts mods and RealFuels, I find myself more often than not building (what seems to me to be) over-sized rockets. A newbie's mistake, I believe, as I am completely puzzled by the large amount of engine choices, and I don't know exactly what I should take into account when I select an engine for any particular stage. I know to keep an eye on my TWR for the first stage, or my rocket won't get off the ground. I also have an idea of the dV I will need for any particular mission/stage, and I try to build a rocket that will top that requirement. But keeping only this in mind, I feel that my rocket building process resembles more of an arms-race between fuel weight and dV, rather than a guided, calculated process. So my questions are: how do you select the proper engines for the stages of the rocket? Are there any guidelines? Am I correct in assuming that higher Isp and lower engine mass is better? How do you factor in thrust and type of fuel? What are the energy densities (if that's the correct term) of various fuels, and how does that affect the choice? Is there anything else I should be thinking about at design-time (concerning staging, engines and fuel) to ensure a fuel-efficient launch? Thanks for your thoughts, Dan

Well, I just noticed the same phenomenon on another rocket I just build, so I guess it's about the same thing as what you were suggesting. My money now's on a problem with one of the mods I'm using. I will try removing them one at a time and see if that helps.

A couple of you suggested it may be that the engine is in the "Staging" action group - it's not this, checked again.

This happens event when doing a manual lift-off.

On the launchpad, the event log is clean - no disassembly. Thanks! This is most useful.

On the launchpad, apart from the pitch-trim/gimbal/thrust controls, I have the options to Jettison, Toggle, and Activate Engine. If I press "Activate Engine", that changes to "Shutdown Engine" (having done this throttled down, though, there was no actual engine start-up).

As parts go, I'm using RealEngines, ProceduralFairings, ProceduralParts, AIES_Aerospace, MechJeb2, KWRocketry, RealChute, RealFuels. They're all the latest versions. I will check out the link you gave me and see if I find anything there. Thanks. I think my first five comments needed to go through a moderation process, now I'm good to go however.

Alas, it's not this. I have no "Shutdown engine" option in the VAB. The option is there during flight, though.

Yes, I checked by mousing over the icons. And yes, I'm sure the (second) engine is on, I can see it depleting fuel. I uploaded the craft file and a pic (post #3).

No worries, I've dealt myself with PEBKAC many times I triple-checked. It's not the staging (as far as I can tell). Maybe you guys can see something I don't?

Thanks, I'm still a little new at this. This is the subject. At lift-off, the engines from both stages 8 and 5 activate. Craft file: https://www.dropbox.com/s/h3kgu93lntbhq1a/LEO%20Probe.craft Thanks!

Or, considering the orbital energy, acceleration is somehow equivalent to the concept of orbital power, if there is such a thing. Does this make any sense to somebody more physics-savvy? Dan

Hello! My name is Dan, and this is my first time posting on the forum. I have a question regarding staging. On some rockets, when I activate the first stage for take-off, it happens that engines from subsequent stages activate as well. My staging is correct, and my 'stage' action group is empty. Is there anything else I should be checking? I can't understand why this is happening. Thanks for your thoughts! Dan