Vertical Ascent vs. To LXO First

[GoSlash27]

If you are asking me how much deltaV vertical ascent takes? You can look it up in my video? Otherwise, not sure what you are asking....

Also, rather that asserting it is "incorrect", I would appreciate if you explain why, rather than cockily asserting your knowledge trumps mine.

Yes, that's what I'm asking you. How much DV did your ascents take total? You posted them and you have the video. How much total DV did they take?

I posted the numbers for my tests in stock KSP. What were they for your test in FAR?

[GoSlash27]

No, the reason you've reposted it here is the same reason you've been reposting it all these other times; you don't want to accept that your "vertical launch" theory is incorrect.

It may be easier and even more reliable, but it is not ever, under any circumstances, more efficient.

Now that's 5 times I've asked you for the numbers. We could clear this up if you'd just tell me, but you haven't said what they are. Do you not know, or do you just not want to say?

[Kesa]

You basically ignored the concrete mathematical numbers i gave in favor of vertical ascent for this case....

From what I understood, your concrete mathematical numbers just say that without any gravity loss (or with infinite TWR), vertical ascent to an intercept to the mun saves ~20m/s, which is nothing.

But even with high TWR, I bet that vertical ascent is worse than throttling down to TWR = 2 until out of soup and then full throttle with a more brutal turn. However, I can't figure out how worse it is, so it may be not that worse, depending on TWR, escape velocity you want, SOI size...

For small body, TWR is often very high and escape velocity is low, so as someone mentioned before, the best is to accelerate toward the escape velocity you desire, may it be vertical (and vertical is the worse case).

But as for canyons, I don't know at all how to manage them. Maybe full throttle until your apo allow you to burn toward escape velocity. And in that case, vertical escape, when possible, might be the most effective way out, especially for the Mun which has a rather high escape velocity (but since it's tidally lock, you'd better chose your canyon before landing:sticktongue:)

edit : your numbers I'm speaking are those from the previous thread, I did not watch the vid, poor connection

Edited December 15, 2014 by Kesa

[Kesa]

Watched it. It's actual crap:confused:. You only proved that a poorly designed craft is inefficient no matter the way you choose.

[GoSlash27]

Watched it. It's actual crap:confused:. You only proved that a poorly designed craft is inefficient no matter the way you choose.

'Zackly.

Which is why I keep asking for the DV expenditure and why he won't say. If you launch a drag- monster horizontal instead of vertical, then naturally it will lose a little more in drag. Still not enough to cover the inefficiency of going vertical, but closer.

And then he launches into his (incorrect) spiel about "terminal velocity" and how accelerating at a kajillion gees is supposedly more efficient... but if that were true, why does his DV suck so bad?

I ran the same test with an efficient rocket and efficient profiles, and found a huge cost for going vertical.

Best,

-Slashy

Edited December 15, 2014 by GoSlash27

[Wanderfound]

The best way to manage canyons is to try and scrape by within a few metres of the canyon lip while at full throttle.

I have no idea if that will be most efficient, but it's reliably the most fun.

[arkie87]

The best way to manage canyons is to try and scrape by within a few metres of the canyon lip while at full throttle.

I have no idea if that will be most efficient, but it's reliably the most fun.

Should be the most efficient; also a way to get kerbal's blood pumping (do they have blood? green blood?)

You want you climb as little as needed and burn as horizontally as possible as fast as possible, if you arent going the vertical approach.

[arkie87]

'Zackly.

Which is why I keep asking for the DV expenditure and why he won't say.

Best,

-Slashy

I wont say because you can get them yourself since i posted the video with those numbers. But since you insist, here are the numbers:

Vertical ascent: 3313 m/s

LKO-to-Mun: 3241 m/s

Using readouts from KER.

Your numbers:

Vertical ascent:

Vertical: 5570 m/s

LKO-to-Mun: 5230 m/s

Now what is your point?

[arkie87]

No, the reason you've reposted it here is the same reason you've been reposting it all these other times; you don't want to accept that your "vertical launch" theory is incorrect.

It may be easier and even more reliable, but it is not ever, under any circumstances, more efficient.

Now that's 5 times I've asked you for the numbers. We could clear this up if you'd just tell me, but you haven't said what they are. Do you not know, or do you just not want to say?

First of all, you are being rude. You mentioned somewhere that you like helping people. If that is true, and your intentions are that, then you should really tone down the rudeness.

As i have said many times in other threads where we argued, I dont care if I am right or wrong. I want to know why. So if you want to help me, tell me why I am wrong. Not start putting words in my mouth or otherwise insult me. That is no way to behave on the forums.

And for the love of god, I dont claim it is more efficient. I am just trying to highlight its advantages, since conventional knowledge recommends avoiding it at all costs. But even according to your results, it only costs less than 10% more deltaV.

[arkie87]

'Zackly.

Which is why I keep asking for the DV expenditure and why he won't say. If you launch a drag- monster horizontal instead of vertical, then naturally it will lose a little more in drag. Still not enough to cover the inefficiency of going vertical, but closer.

And then he launches into his (incorrect) spiel about "terminal velocity" and how accelerating at a kajillion gees is supposedly more efficient... but if that were true, why does his DV suck so bad?

I ran the same test with an efficient rocket and efficient profiles, and found a huge cost for going vertical.

Best,

-Slashy

Really? you think terminal velocity is not optimal? Please explain why not? I already provided the equations which suggest it is...

My dV doesnt suck so bad. I posted the numbers (which you could have gotten yourself), what now?

Once again, you arent using FAR... I've already explained that terminal velocity is easy to hit in stock aerodynamics

[GoSlash27]

I wont say because you can get them yourself since i posted the video with those numbers. But since you insist, here are the numbers:

Vertical ascent: 3313 m/s

LKO-to-Mun: 3241 m/s

Using readouts from KER.

Your numbers:

Vertical ascent:

Vertical: 5570 m/s

LKO-to-Mun: 5230 m/s

Now what is your point?

Your numbers from KER are misleading you. FAR requires a minimum of 3,500 m/sec to establish orbit according to the wiki.

What was your vehicle's total mass during launch and at cutoff? I'll figure it for you.

Edited December 15, 2014 by GoSlash27

[B787_300]

EVERYONE, please stop for a moment and remember that the community rules (especially Rule 2.2)

NOW if everyone please post pics of craft used and DV readouts from KE or MJ this would be a LOT easier to sort out.

[arkie87]

From what I understood, your concrete mathematical numbers just say that without any gravity loss (or with infinite TWR), vertical ascent to an intercept to the mun saves ~20m/s, which is nothing.

Oh. I read below. See below for response.

But even with high TWR, I bet that vertical ascent is worse than throttling down to TWR = 2 until out of soup and then full throttle with a more brutal turn. However, I can't figure out how worse it is, so it may be not that worse, depending on TWR, escape velocity you want, SOI size...

Where did TWR = 2 come from? Unless you are above terminal velocity, throttling down is not the right option since you want to get into orbit ASAP...

For small body, TWR is often very high and escape velocity is low, so as someone mentioned before, the best is to accelerate toward the escape velocity you desire, may it be vertical (and vertical is the worse case).

Who mentioned this? This is exactly what I am saying....

But as for canyons, I don't know at all how to manage them. Maybe full throttle until your apo allow you to burn toward escape velocity. And in that case, vertical escape, when possible, might be the most effective way out, especially for the Mun which has a rather high escape velocity (but since it's tidally lock, you'd better chose your canyon before landing:sticktongue:)

Yeah, this is the problem. It wont happen on Mun often, since you would have to land in the right spot since it's tidally locked. But still. It's a hypothetical argument...

edit : your numbers I'm speaking are those from the previous thread, I did not watch the vid, poor connection

My numbers say vertical ascent is 70 m/s worse than horizontal in FAR (not the other way around), which, IMHO, isnt much. I'm not saying you should do vertical ascent or vertical ascent is more efficient (which GoSlash27 for some reason thinks I am saying), but the common knowledge that vertical is woefully inefficient isnt true in this case.

Furthermore, for the case we are discussing in this thread, it seems that vertical ascent is more efficient....

[GoSlash27]

First of all, you are being rude. You mentioned somewhere that you like helping people. If that is true, and your intentions are that, then you should really tone down the rudeness.

As i have said many times in other threads where we argued, I dont care if I am right or wrong. I want to know why. So if you want to help me, tell me why I am wrong. Not start putting words in my mouth or otherwise insult me. That is no way to behave on the forums.

And for the love of god, I dont claim it is more efficient. I am just trying to highlight its advantages, since conventional knowledge recommends avoiding it at all costs. But even according to your results, it only costs less than 10% more deltaV.

If any of this were true, you would spend less time arguing and more time listening.

And yeah, you're trying to "highlight it's advantages". That's why you're continually posting these threads.

The reason you're working so hard to "highlight it's advantages" is because it's hard for you to fly a proper gravity turn and you want someone else to validate your reasons for not doing that.

You don't *need* anyone else to validate your choice. Fly like you want to fly. But what you're posting here is highly confusing and misleading to the newbies who are going to read this later on. That's a disservice to them, and I don't personally care for it.

Rockets that glow on the way up are bad. Launching straight up is bad. It's inefficient and wasteful.

Disabling atmospheric stress because you can't make rockets work properly is bad.

Maybe that's *your* thing, but it's not good advice to pass onto others and I'm tired of arguing with you about it when you're not listening.

Now... when you grow tired of wasting all that energy and want me to explain to you where you're going wrong (and actually *listen*), I will be more than happy to lend you a hand. Until then, play your game however you see fit.

Regards,

-Slashy

Edited December 15, 2014 by GoSlash27

[arkie87]

Your numbers from KER are misleading you. FAR requires a minimum of 3,500 m/sec to establish orbit according to the wiki.

What was your vehicle's total mass during launch and at cutoff? I'll figure it for you.

Yeah, something weird is happening in KER, since during launch, deltaV values for upper stage were changing when they shouldnt be since the fuel wasnt being shared...

From KER, i think the numbers are as follows (KER reports two numbers. I assume the first is current stage and second is total, so i report total):

Initial Mass (both cases): 47428 kg

LKO-to-Mun: 15458 kg (only lower stage burned; upper stage untouched)

Vertical Ascent: 4688 kg (lower stage used completely)

Let me know what you find. I will crunch numbers too.

[arkie87]

If any of this were true, you would spend less time arguing and more time listening.

And yeah, you're trying to "highlight it's advantages". That's why you're continually posting these threads.

The reason you're working so hard to "highlight it's advantages" is because it's hard for you to fly a proper gravity turn and you want someone else to validate your reasons for not doing that.

You don't *need* anyone else to validate your choice. Fly like you want to fly. But what you're posting here is highly confusing and misleading to the newbies who are going to read this later on. That's a disservice to them, and I don't personally care for it.

Rockets that glow on the way up are bad. Launching straight up is bad. It's inefficient and wasteful.

Disabling atmospheric stress because you can't make rockets work properly is bad.

Maybe that's *your* thing, but it's not good advice to pass onto others and I'm tired of arguing with you about it when you're not listening.

-Slashy

I could make the same argument for you that you are just arguing and not listening. We obviously both think we are right... But the difference is, when i argue, i make an argument with math or logic rather than claim the other side is wrong. Claiming the other side is wrong without supporting evidence is pointless...

From my side, it seems you arent listening either. You repeatedly use arguments that i've argued apply to stock aero only, and not FAR, even after ive explained why and how stock and FAR are different. Furthermore, you've never addressed the terminal velocity argument other than claiming its wrong without providing a reason.

Please follow community rules, as per B787_300.

And the fact that my rocket is glowing from re-entry effects on liftoff says nothing. You still haven't refuted my claim that terminal velocity is what matters-- not rerentry effects.

Edited December 15, 2014 by arkie87

[arkie87]

Yeah, something weird is happening in KER, since during launch, deltaV values for upper stage were changing when they shouldnt be since the fuel wasnt being shared...

From KER, i think the numbers are as follows (KER reports two numbers. I assume the first is current stage and second is total, so i report total):

Initial Mass (both cases): 47428 kg

LKO-to-Mun: 15458 kg (only lower stage burned; upper stage untouched)

Vertical Ascent: 4688 kg (lower stage used completely)

Let me know what you find. I will crunch numbers too.

Actually, i think numbers changed due to ISP changing because of atmosphere density...

[Kesa]

TWR of 2 comes from your holy terminal velocity. The definition of terminal velocity (http://en.wikipedia.org/wiki/Terminal_velocity) is the velocity at which drag equals gravity. Basic math show that with TWR = 2 you're sure to stay under terminal velocity (and close to if it's not raising to quick).

I can't find where on the wiki it's prove but you seem to agree that terminal velocity is the optimal velocity to make vertical ascent.

And with the reentry effect, I highly doubt you are under terminal velocity. You may be misleaded because you use FAR and mech jeb. As stated here in the FAQ : http://forum.kerbalspaceprogram.com/threads/20451-0-25-Ferram-Aerospace-Research-v0-14-4-11-24-14, FAR changes aerodynamic in a way that does not allow mech jeb (and maybe KER) to give relevant terminal velocity.

[Kesa]

For small body, TWR is often very high and escape velocity is low, so as someone mentioned before, the best is to accelerate toward the escape velocity you desire, may it be vertical (and vertical is the worse case).

I was speaking of Slashy answer, which is clearer than mine, so let's quote it :

*edit* on the subject of munar escape, prograde acceleration as rapidly as possible. Always and no matter what circumstances. Vertical costs you more in gravity losses, robs you of free velocity from rotation, and kills your Oberth effect gains.

Best,

-Slashy

Edited December 15, 2014 by Kesa
added quote

[arkie87]

TWR of 2 comes from your holy terminal velocity. The definition of terminal velocity (http://en.wikipedia.org/wiki/Terminal_velocity) is the velocity at which drag equals gravity. Basic math show that with TWR = 2 you're sure to stay under terminal velocity (and close to if it's not raising to quick).

I can't find where on the wiki it's prove but you seem to agree that terminal velocity is the optimal velocity to make vertical ascent.

And with the reentry effect, I highly doubt you are under terminal velocity. You may be misleaded because you use FAR and mech jeb. As stated here in the FAQ : http://forum.kerbalspaceprogram.com/threads/20451-0-25-Ferram-Aerospace-Research-v0-14-4-11-24-14, FAR changes aerodynamic in a way that does not allow mech jeb (and maybe KER) to give relevant terminal velocity.

TWR = 2 doesnt mean you are at terminal velocity-- it just means its physically impossible to exceed it. If you are in space, terminal velocity is infinity, and TWR will not make you reach infinity....

As i said before, in stock, terminal velocity is small--only 100 m/s at sea level-- so TWR = 2 will make you reach terminal velocity quite quickly. From then on, its only a matter of maintaing terminal velocity, which changes with air density in stock. In FAR, terminal velocity starts out much higher, due to low density of atmosphere relative to density of spaceship. It is much harder to get to without huge TWR.

I do agree terminal velocity is optimal. And i can prove it mathematically (albeit for a simple case) if you are interested .

I am positive I am under terminal velocity. FAR itself calculates terminal velocity-- and I get all reading from FAR itself.

I was not, and never was, using MechJeb (don't know where you got that from) nor was i getting any numbers from there...

Edited December 15, 2014 by arkie87

[GoSlash27]

I calculated your DV expenditure from the mass.

42.6 tonnes on the pad and 10.7 tonnes at burnout. Looks like a mainsail to me. Please correct me if any of this is incorrect.

Your prograde launch was 4,880 m/sec DV. Minus the correction for overshoot. 9.82Isp* ln(Mw/Md). The math don't lie.

For vertical, it was the same plus your stage 2 burn. I couldn't get the type of engine. Looked like an LV-T30, but not sure.

You were 4,900 m/sec on a mission that should've only been 4,270 for FAR.

So yeah, that's what I mean by "drag- monster". If you've added over 600 m/sec due to inefficiency, *of course* it'll bury some of the 300+ m/ sec you waste by going vertical.

Inefficient rocket is inefficient no matter which way you point it.

Also the point that KER misled you about how much DV you had actually used, just as it did about your terminal velocity.

-Slashy

Edited December 15, 2014 by GoSlash27

[Kesa]

Well, your low quality video shows that you use something that displayed information, but I could not figure out which one it was.

[arkie87]

I was speaking of Slashy answer, which is clearer than mine, so let's quote it :

In that case, I think you are misunderstanding Slashy's answer

[arkie87]

Well, your low quality video shows that you use something that displayed information, but I could not figure out which one it was.

low quality? It's 1080p...

[Kesa]

low quality? It's 1080p...

Sorry, steam navigator sucks (it's the first time it makes me that though).

Watching it with chrome