Burn times

[hhatch]

I have just started playing KSP and I'm going through the Scott Manley tutorials. I just completed #4 Orbiting the Mun. One of the issues that keeps popping up is long burn times when going into orbit or injecting into an orbit. When I say long I'm talking over a minute. Most of my burn times have been less than 30 seconds. I made it into Mun orbit but ran out of fuel before I could get back to Kerbin. I imagine my poor rocket design contributed greatly to that problem. However I think the burn times ate up a lot of fuel as well.

 

I did some experimenting and found a couple of things. When going into orbit around Kerbin I turn pretty close to 90 degrees east at about 10 Km  and continue on that path until the navball flips to orbit and then I  follow the prograde vector. The suggested turn to 45 degrees seemed to produce a steeper path to apoasis and resulted in some much longer burns.

 

When I made it to Mun orbit and was going back to Kerbin the video suggested creating a maneuver at about a 45 degree angle which I did but I was getting extremely elongated orbits and burn times that went for hours. I tried creating a manuever in a direct line to Kerbin and that seemed to work. I finally got home in one piece. I did notice that Scott"s orbit was more circular than mine so I don't know if the shape of the orbit my have had some affect.

 

I'm very new and just trying to get a grasp on the basics of orbital mechanics.

 

This is a very interesting and challenging game. I like the navigation aspects and I think learning to build rockets would be fun although I have no technical background so I'm not sure how that will go.

 

Henry

 

 

[bewing]

Welcome to the forums.

Burn times are related to your thrust. Which depends on the size and number of your engines. Having many big powerful engines is inefficient. So short burn times are bad, actually.

A burn time of 2 to 3 minutes is very common for reasonably efficient rockets. Extremely efficient ion engine rockets have burn times of hours, often.

Once you are in space, you don't need a lot of thrust. In fact, smaller engines have less mass, and reducing the mass of your rocket is one of the most important optimizations that you can do.

Once burn times last longer than about 10% of your orbital time, they do start to become inefficient, though, it is true.

 

[Zeiss Ikon]

If you're using Swivels or Reliants for your Mun craft, you'll get shorter transfer burns than Scott would with a Terrier engine.  That's because the larger engines have much more thrust -- but they burn more fuel for each unit of impulse (impulse is thrust times time, has the units of momentum, mass times velocity).  Thus, if you have two identical craft (say, a Mk. 1 command pod, with parachute and heat shield, decoupler, FL-T400 tank, and some kind of engine), one with a Reliant (slightly more efficient than a Swivel, and you don't need the gimbal for this part of the mission) will burn more fuel for the same transfer than one with a Terrier.  This occurs both because the Terrier has higher specific impulse (the measure of efficiency for rocket engines), and because the Reliant is much heavier.

That said, over time, you may prefer a Reliant or Swivel over a Terrier for some missions, because the Terrier doesn't have an alternator and can't charge your craft's batteries -- and running out of electric charge can make it almost as hard to get home to Kerbin as running out of fuel.  The difference in efficiency is noticeable, but it may not offset the extra weight of having to carry two or three extra battery packs for a 3-4 day mission profile.

[Rocket In My Pocket]

Welcome to the forums!

To add another tidbit of advice to @bewing's excellent explanation;

To make your burns more accurate (and therefore efficient) you should burn half before the maneuver node and half after, splitting up your burn. So basically if you had a minute long burn for example: you would start burning at 30 seconds out. This is more important the longer the burn.

[Cpt Kerbalkrunch]

@hhatch, I've only seen a couple of Scott Manley videos, so I can't speak to their value in learning to play. From my own experience though, I highly recommend going through the in-game tutorials. I found them highly informative, and fun as well because it was all new and exciting. They're at least worth a look.

[Urses]

Welcome to the forums.

Bewing answered some of your questions. But one thing has catched my eye. Yor turn to 90° at 10 km...

At 10 km your engine ISP is realy bad and this means you need much more fuel to get the same velocity addition as in much thinner air layers. Additionaly in lower air layers the drag aspect is way higher as in upper layers, you feed your fuel away to fight the drag and at lower efficiency.

As example this is one of the aspects why a airplane is slick and a spaceship in vacuum will fly as can.

And maneuvernodes ploting gives you the ability to hit a target every where but your target is not only the bullseye but a economical one.

And pay attention to Scotts videos his beginner guides where made as KSP did not know about atmosphere drag or reentry heat

Edited November 10, 2017 by Urses

[Helmetman]

It's very hard to put your description into visualisation as you have currently written it. I went over it a few times, and can't exactly make up what you say. 
Can you make a screenshot of the following things...

2 hours ago, hhatch said:

When going into orbit around Kerbin I turn pretty close to 90 degrees east at about 10 Km  and continue on that path until the navball flips to orbit and then I  follow the prograde vector. 

A pic of what you mean concerning the quote above? Meaning: When you execute said maneuver.

2 hours ago, hhatch said:

The suggested turn to 45 degrees seemed to produce a steeper path to apoasis and resulted in some much longer burns.

You turn to 45 degrees pitch at 10 kilometer altitude, no? At which altitude? You want to turn much sooner, a few degrees atleast a few seconds after lift off. Search the term gravity turn, perhaps on youtube, I'm sure there are some videos that explain it concerning KSP.

Is Scott manleys video on youtube several years old? If true, know that the game has changed a lot since then. Scott's tutorials don't always apply for the current KSP version.

Show me a pic of the scenario of the exact quote above. If you turn 45 degrees at 10km altitude and keep burning your likely to get a steep ascent. you'll have to follow the prograde marker in a gravity turn when past most of the atmosphere at about 20-30km altitude. Just keep burning and switch to map mode occasionally to see if the Ap (apoapsis) is above 70km. If it is, just timewarp to there and face prograde and keep burning until the orbit is completely circular.

2 hours ago, hhatch said:

When I made it to Mun orbit and was going back to Kerbin the video suggested creating a maneuver at about a 45 degree angle which I did but I was getting extremely elongated orbits and burn times that went for hours. 

45 angle to what exactly? Usually you turn 90 degrees east to orbit the Mun just as you do on Kerbin. Then you burn facing prograde on the side of the Mun facing Kerbin and keep burning until the orbit line intersects with Kerbins atmosphere.

A pic of this also por favor.

2 hours ago, hhatch said:

 I tried creating a manuever in a direct line to Kerbin and that seemed to work.

A direct line meaning you faced to the planet Kerbin and then started your burn? This is not a very efficient way, good you made it home though. I'm probably analyzing this wrong, but it's so hard to tell based on how you specified that part. No hard feelings, I know your new 

A pic of that also.

2 hours ago, hhatch said:

I'm very new and just trying to get a grasp on the basics of orbital mechanics.

When searching for tutorials on youtube make sure the videos are dated from early may 2015 until present. The other videos are from ancient KSP versions that use a substitute for the current atmosphere that is very thick and soupy. Which are many of Scott manely's videos I'm afraid.

In those earlier versions different rules for orbiting apply that makes no sense in the current version of KSP. It's best to check the date and only watch the tutorials past the date I specified.

edit: You can take a pic, meaning pictures by pressing F1 in flight. In your KSP directory is a screenshot folder, there they'll be stored. Go to imgur.com, upload these pics and copy/paste the image links into this forum.

Edited November 10, 2017 by Helmetman

[hhatch]

2 hours ago, Rocket In My Pocket said:

Welcome to the forums!

To add another tidbit of advice to @bewing's excellent explanation;

To make your burns more accurate (and therefore efficient) you should burn half before the maneuver node and half after, splitting up your burn. So basically if you had a minute long burn for example: you would start burning at 30 seconds out. This is more important the longer the burn.

I am aware that splitting the burn time helps accuracy. In the Scott Manley video I noticed he did not always split burn times when doing a maneuver. I don't know why.

[hhatch]

2 hours ago, Cpt Kerbalkrunch said:

@hhatch, I've only seen a couple of Scott Manley videos, so I can't speak to their value in learning to play. From my own experience though, I highly recommend going through the in-game tutorials. I found them highly informative, and fun as well because it was all new and exciting. They're at least worth a look.

I have actually gone through half of the in game tutorials. The only issue I had was that I can't do a quick save in a tutorial. On one tutorial I got stuck on something right at the end and had to keep starting the whole thing over because I could not quick save.

[A_name]

4 hours ago, hhatch said:

I have just started playing KSP and I'm going through the Scott Manley tutorials. I just completed #4 Orbiting the Mun. One of the issues that keeps popping up is long burn times when going into orbit or injecting into an orbit. When I say long I'm talking over a minute. Most of my burn times have been less than 30 seconds. I made it into Mun orbit but ran out of fuel before I could get back to Kerbin. I imagine my poor rocket design contributed greatly to that problem. However I think the burn times ate up a lot of fuel as well.

1 minute burns are totally fine. A long burn I would consider to be above 5 or 10 minutes. Just make sure you split your burn time half way before and after the maneuver node.

4 hours ago, hhatch said:

I did some experimenting and found a couple of things. When going into orbit around Kerbin I turn pretty close to 90 degrees east at about 10 Km  and continue on that path until the navball flips to orbit and then I  follow the prograde vector. The suggested turn to 45 degrees seemed to produce a steeper path to apoasis and resulted in some much longer burns.

This is totally the wrong way to launch in the new versions. See this tutorial: 

 

 

[hhatch]

2 hours ago, Helmetman said:

It's very hard to put your description into visualisation as you have currently written it. I went over it a few times, and can't exactly make up what you say. 
Can you make a screenshot of the following things...

A pic of what you mean concerning the quote above? Meaning: When you execute said maneuver.

You turn to 45 degrees pitch at 10 kilometer altitude, no? At which altitude? You want to turn much sooner, a few degrees atleast a few seconds after lift off. Search the term gravity turn, perhaps on youtube, I'm sure there are some videos that explain it concerning KSP.

Is Scott manleys video on youtube several years old? If true, know that the game has changed a lot since then. Scott's tutorials don't always apply for the current KSP version.

Show me a pic of the scenario of the exact quote above. If you turn 45 degrees at 10km altitude and keep burning your likely to get a steep ascent. you'll have to follow the prograde marker in a gravity turn when past most of the atmosphere at about 20-30km altitude. Just keep burning and switch to map mode occasionally to see if the Ap (apoapsis) is above 70km. If it is, just timewarp to there and face prograde and keep burning until the orbit is completely circular.

45 angle to what exactly? Usually you turn 90 degrees east to orbit the Mun just as you do on Kerbin. Then you burn facing prograde on the side of the Mun facing Kerbin and keep burning until the orbit line intersects with Kerbins atmosphere.

A pic of this also por favor.

A direct line meaning you faced to the planet Kerbin and then started your burn? This is not a very efficient way, good you made it home though. I'm probably analyzing this wrong, but it's so hard to tell based on how you specified that part. No hard feelings, I know your new 

A pic of that also.

When searching for tutorials on youtube make sure the videos are dated from early may 2015 until present. The other videos are from ancient KSP versions that use a substitute for the current atmosphere that is very thick and soupy. Which are many of Scott manely's videos I'm afraid.

In those earlier versions different rules for orbiting apply that makes no sense in the current version of KSP. It's best to check the date and only watch the tutorials past the date I specified.

edit: You can take a pic, meaning pictures by pressing F1 in flight. In your KSP directory is a screenshot folder, there they'll be stored. Go to imgur.com, upload these pics and copy/paste the image links into this forum.

Thanks for the response. I will try and get some pics up. I have a flickr account and I'm assuming I could upload there and then copy/paste.

 

Sorry I was not clear in my explanations. Let me try and clarify a couple of things.

 

The Scott Manley videos all seem to have been published in 2014. If anyone has some suggested recent videos that would be helpful. The video on getting into orbit says to turn about 45 degrees at 10 km which is what I originally did. I found that turning closer to 90 degrees at 10 km got me better results.   When I was orbiting the Mun (a different video lesson from the getting into orbit video)  I was trying to create an intercept orbit (encounter) in order to get back to Kerbin. I created a maneuver at a place in the Mun orbit in a direct line to Kerbin. There is a lot of info out there. I am just a bit overwhelmed trying to process so much new info. It reminds me of when I first got into flight simulations almost 20 yrs ago. Hate being a noob.

[Cpt Kerbalkrunch]

40 minutes ago, hhatch said:

I have actually gone through half of the in game tutorials. The only issue I had was that I can't do a quick save in a tutorial. On one tutorial I got stuck on something right at the end and had to keep starting the whole thing over because I could not quick save.

Yeah, that's a definite pain. Because of it, I didn't even know about F5/F9 for my first couple weeks. Each time I crashed into the Mun, I would revert to launch and do the whole thing over again. That's a real shortcoming in the tutorials.

As to why someone would split a burn sometimes but not others, I would assume he had a very low power engine like the Nerv or Dawn. They take quite a bit longer to perform a maneuver, so that by the time you finish your burn, you're no longer where you were supposed to be. This can completely throw you off your target orbit. It's why I stick with pure chemical engines. When I want to burn, I want it to happen now. Anything over a minute and a half, I would consider a long burn. I just don't have the patience for low TWR vessels.

[Snark]

6 hours ago, Urses said:

At 10 km your engine ISP is realy bad

Actually, this is not the case.  At 10 km, engine Isp is great and vacuum engines such as the Terrier and Poodle work just fine.  Bear in mind that at 10 km, the atmospheric pressure is only about 1/6 of sea level, i.e. you're already 84% of the way to vacuum.  And it gets even thinner in a hurry above that.

3 hours ago, hhatch said:

The Scott Manley videos all seem to have been published in 2014. If anyone has some suggested recent videos that would be helpful. The video on getting into orbit says to turn about 45 degrees at 10 km which is what I originally did.

Yep, that's completely wrong now, don't do it.  As soon as I saw you posting earlier in the thread about "climb to 10 km and turn 45 degrees", I immediately thought, "he's probably watching old videos."    That's because, before KSP 1.0, that was the conventional wisdom about the "right" way to go to orbit.  No more, not even vaguely.

So, what is the "right way"?  Well there are a lot of different ways to do it, and it depends what you're trying to optimize for, and the TWR of your rocket, and so forth.  But regardless of your ship design, there are some general principles:  in particular, don't make any sharp turns.  Basically, your rocket should be sticking to pretty much all the way up.  This is called a "gravity turn".  Basically, you make a slight eastward turn practically right off the pad, then just follow your nose all the way up until your Ap gets to the height you want, then coast.

Just how much that "slight eastward turn" should be will depend on various things, most importantly your TWR.  Higher TWR rockets will need a more aggressive eastward turn; lower TWR rockets will need a gentler one.  Here's a reasonable rule of thumb:  Just try it, pick some angle and see what happens.  Follow at full thrust until you reach an angle of 45 degrees.  How fast are you going?  If you're going 300-400ish m/s at that point, you're good to go.  If you're going any slower than 300 m/s, you turned too much; revert and try a slightly gentler turn.  If you're going a lot faster than 400 m/s when you hit 45 degrees, then you didn't turn enough-- revert and try turning a bit more.

With a little bit of practice, pretty soon you'll develop a good feel for how much of a turn you need.  One thing that can help with this is if you try to keep your TWR as consistent as possible-- that is, if you always design your rockets to have the same TWR.  That makes life easy because rockets with the same TWR will generally need about the same amount of "nudge", so it's easier to practice and develop a consistent launch profile.  (In my own case, I like to go for a launchpad TWR of 2.0, or slightly higher for big ships.  Lower TWR can work, too.  It's largely a matter of personal taste and design philosophy.)

 

[Urses]

6 hours ago, Snark said:

Actually, this is not the case.  At 10 km, engine Isp is great and vacuum engines such as the Terrier and Poodle work just fine.  Bear in mind that at 10 km, the atmospheric pressure is only about 1/6 of sea level, i.e. you're already 84% of the way to vacuum.  And it gets even thinner in a hurry above that.

You are right but in this example 84% for seconds don't do a big change but like said by him self he stays at 10 km till ge reaches orbital velocity. And if he follows Scotts example, he used up 1/5 more of fuel at this moment as Scott and changes many other things, like not to burn on Ap/Pe and so on. Best is his comment "i found another point for planning maneuver at 45°, but is this the fuel efficientest point? And as we see by his own comment it is not. The problemm is he runs of fuel.

And if i try Scotts flying routine with actual mechaniks i mostly have enough fuel for 2-3 biom hops additionaly?

The only thing i am wondering is, had he disabled heat gauge or scaled it down? Because a speedrun between 10 and 20 km gives mostly beautiful fireflies...

Edited November 11, 2017 by Urses
T9 + big diggits...much confusion

[Spricigo]

Scott Manley's KSP 1.0Tutorial:

Still have some differences to current version but a reasonable good tutorial series.

 

[Urses]

 

This one may be helpfull as well and for ksp 1.x.x. Marcus play heavy moded installs and use KOS but the beginner guides and tipps for early carrier stages are good. Try out... and best advice look where your priorities are. Set you one target for first time like cheapest lifter, biggest payload in one start, most contracts in one mission and try to get better for this one prime target. If you try to many aspects at one time you will only confuse your self.

Edited November 11, 2017 by Urses

[Starchaser]

12 hours ago, Helmetman said:

Just keep burning and switch to map mode occasionally to see if the Ap (apoapsis) is above 70km. If it is, just timewarp to there and face prograde and keep burning until the orbit is completely circular

Good morning hhatch. Welcome to KSP!

As an alternative to this comment, you may want to look into a mod such as Kerbal Engineer Redux, (abbreviated KER) which will put your Ap and other relevant information on the screen at all times. I know I still get flustered when I need to flip back and forth quickly.

12 hours ago, Helmetman said:

edit: You can take a pic, meaning pictures by pressing F1 in flight. In your KSP directory is a screenshot folder, there they'll be stored. Go to imgur.com, upload these pics and copy/paste the image links into this forum

If you're running KSP from steam, you can also use F12 which is steam's screenshot key. I do it the hard way, hit prt Scr pause the game and open paint. Saves me editing time later.

6 hours ago, Snark said:

Bear in mind that at 10 km, the atmospheric pressure is only about 1/6 of sea level, i.e. you're already 84% of the way to vacuum.  And it gets even thinner in a hurry above that

Not quite right. This is an area of my RL expertise, as I work for an airplane manufacturer. At 33,000 feet,  (10,000m) atmospheric pressure is around 4 psi, compared to about 14.5 at sea level.  However the point is very valid that Isp improves rapidly from there. At our jet's cruising altitude of 43,000 the pressure is 2.35 ish for example. Or about Snark's 1/6

[Plusck]

Seriously, do NOT take too much of Scott Manley's videos into account. A lot of it is simply not valid for current versions of KSP. Last time I checked he still hadn't added a disclaimer to his videos saying that they don't work anymore, but maybe one day he will...

 

To get to orbit cheaply with a decent powered and streamlined rocket (say a Reliant with two FL-T400s and one FL-T100 above it plus two Hammer SRBs on the side, then upper stage with Terrier and one FL-T400, then Mk1 pod with minimal heatshield (remove most ablator) and no monoprop (remove it too in the VAB) - giving about 22 parts and 17.7 tonnes total (no VAB or launchpad upgrades needed) - you want to drop the nose to about 75° on launch, then follow prograde. Your nose should drop through 45° at about 6000m-8000m.
With such an aggressive drive towards the horizon, overheating is the main worry but you should end up in orbit with about 3/4 of a tank left in the upper stage. That's over 1800m/s... More than enough to orbit the Mun and then come back. Enough even to land (but not get back to orbit). Or enough to go to Minmus and land and come back.

The alternative system for getting to orbit efficiently (in stock) is to use "follow prograde", then switch to map view once you're over 10km / heading below 45° and just use the throttle to keep the time to Ap (you can right click Ap and it'll tell you) constantly between 40 and 50 seconds. Lower is better but heat, again, can become a problem at around 30km altitude with a shallow ascent.
 

To get to the Mun without manouvre nodes, burn prograde as soon as you see it rise above the horizon, then watch the map.

Coming back from low Mun orbit (say 20km), you basically want to wait until Kerbin rises well above the horizon. While pointing prograde (and facing prograde with the camera), you should wait until Kerbin is getting near the edge of your field of view, so in fact you are aiming at a point just under halfway between the Mun surface and Kerbin. Burning prograde and watching the map, again, you should easily get a good return orbit with Pe at about 30km.

[Snark]

11 hours ago, Snark said:

At 10 km, engine Isp is great and vacuum engines such as the Terrier and Poodle work just fine.  Bear in mind that at 10 km, the atmospheric pressure is only about 1/6 of sea level, i.e. you're already 84% of the way to vacuum.  And it gets even thinner in a hurry above that.

4 hours ago, Starchaser said:

Not quite right.

Actually, it is right. 

4 hours ago, Starchaser said:

This is an area of my RL expertise, as I work for an airplane manufacturer. At 33,000 feet,  (10,000m) atmospheric pressure is around 4 psi, compared to about 14.5 at sea level.

Neat job, congratulations!     And I'm sure your RL expertise is accurate... except that it's not actually relevant here.

Remember, we're not talking  about RL.  We're talking about KSP-- that's what this thread is about, for a KSP player flying a KSP ship on a KSP planet who's trying to figure out how to design and fly his ship.

In KSP.

And Kerbin is not Earth.  On Kerbin, the scale height of the atmosphere is 5.6 km.  e^{-(10km/5.6km)} = 0.167, i.e. about 17%.  (It's not quite as simple as that-- the KSP atmosphere isn't exactly a simple exponential curve, they've tweaked it a bit for varying temperature etc. to try to make it more realistic.  But it's pretty close to that.)

In any case:  even if you don't believe me, it's a pretty quick experiment to run in-game. 

 

[hhatch]

Here are some screenshot of what I've been doing.

[Snark]

9 minutes ago, hhatch said:

Here are some screenshot of what I've been doing.

FYI, not seeing the screenshots, here.  If you're having trouble posting screenshots here, you're not alone-- it's not super obvious how to post, if you haven't done it before.  Here's what you do:

1. Take a screenshot in-game
2. Post it to some third-party image hosting site, for example imgur.com
3. Whichever place you post it:  open that page in your browser, right-click on the image, choose "Copy Image Location"
4. Paste that URL into your post.
5. Presto!  It will get automagically converted into an in-line image.

[hhatch]

8 minutes ago, Snark said:

FYI, not seeing the screenshots, here.  If you're having trouble posting screenshots here, you're not alone-- it's not super obvious how to post, if you haven't done it before.  Here's what you do:

1. Take a screenshot in-game
2. Post it to some third-party image hosting site, for example imgur.com
3. Whichever place you post it:  open that page in your browser, right-click on the image, choose "Copy Image Location"
4. Paste that URL into your post.
5. Presto!  It will get automagically converted into an in-line image.

I can't access my flickr account and so far I can't find a fix. Can I copy the url off steam or do I have to use third party hosting ?

[Snark]

13 minutes ago, hhatch said:

I can't access my flickr account and so far I can't find a fix. Can I copy the url off steam or do I have to use third party hosting ?

You have to have it posted in some location that anonymous public internet users can see.

Why not just use imgur.com, as most forum users do? It's simple, it's quick, and you don't have to have an account. Drag, drop, done.

[OhioBob]

6 hours ago, Starchaser said:

Not quite right. This is an area of my RL expertise, as I work for an airplane manufacturer. At 33,000 feet,  (10,000m) atmospheric pressure is around 4 psi, compared to about 14.5 at sea level.  However the point is very valid that Isp improves rapidly from there. At our jet's cruising altitude of 43,000 the pressure is 2.35 ish for example. Or about Snark's 1/6

@Starchaser, Kerbin's atmosphere is based on the U.S. Standard Atmosphere, with a 20% reduction in the height.  So the pressure that you find at 43,000 feet in real life is found on Kerbin at a height of,

43000 ft * 0.8 * 0.3048 m/ft = 10,485 meters

So Snark is right, the pressure at an altitude of 10,000 m on Kerbin is about 1/6 the sea level value.

If you want to be even more specific, the exact pressures can be computed from Kerbin's pressure curve.  At 10,000 m the pressure is 17.933 kPa, or about 17.7% of sea level.  And the altitude at which the pressure is 1/6 of sea level is 10,306 meters.
 

2 hours ago, Snark said:

In KSP.

And Kerbin is not Earth.  On Kerbin, the scale height of the atmosphere is 5.6 km.  e^{-(10km/5.6km)} = 0.167, i.e. about 17%.  (It's not quite as simple as that-- the KSP atmosphere isn't exactly a simple exponential curve, they've tweaked it a bit for varying temperature etc. to try to make it more realistic.  But it's pretty close 

@Snark, that old constant scale height method gets you in the ballpark, but it can be in error by up to as much as about 19%.  The problem is that scale height is a function of temperature, so it varies by altitude.  It can change by as much as 2 km.

I'm actually the guy who computed the 5.6 km scale height found in the Wiki.  Knowing that is was no longer constant, I had to come up with something close.  What I did was plot a curve of log(pressure) vs. altitude for Kerbin's actual atmospheric pressure (from pressureCurve).  I then found the linear trendline that best matched the curve, from which I computed the scale height.  (A constant scale height produces a straight line when plotting log(P) vs. Z.)   It's as close as we can get for a constant scale height, but it's still not very accurate.
 

Edited November 11, 2017 by OhioBob

[hhatch]

Well I hope these pics make it. This looks wrong too. It takes you to Imgur. Launch 1 is the angle I've been using to launch. Launch 2 is the angle suggested in Scott Manley's video. Both angles were executed starting at 10,000 m. The Mun orbit shows me in mun orbit with a maneuver added to go to Kerbin. Scott Manley suggested placing the maneuver at a 45 degree angle. It appeared from the video that the angle was in relation to Kerbin. The Kerbin encounter is the orbit I created to get to Kerbin. Sorry for the mess I made.

 

 

https://imgur.com/P3Ryrewhttps://imgur.com/v3ApAVWhttps://imgur.com/wqhYPeThttps://imgur.com/K0Ksf

Edited November 11, 2017 by hhatch