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How to figure specific speeds and altitudes for contracts? Without trial and error.


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Hello,

 

A lot of contracts say test this part at this altitude with this speed and it can take hours of trial and error (for a newbie like me) to test 1 part. I want to progress in career mode but at this rate, I'll never get anywhere... so I am wondering is there an easy way to calculate what speed your ship will be doing at altitude X with certain settings? I find it incredibly frustrating to do these kind of contracts, I literally make a note of my engines/settings/stages and then what speed I was doing at what altitude, adjust, try again, fail, cry, adjust, rinse, repeat...

 

Thanks,

Ryan

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With liquid fueled engines, you can control your speed with the throttle. Which takes some practice.

With solid boosters, you need a basic design -- and you need to know how high it goes when full of fuel. You can adjust the fuel load downward in 10% increments, which will reduce your altitude and speed a little. You can play with the thrust limiter which will reduce your altitude and speed a little. You can add fins or science devices or other draggy bits to reduce your altitude and speed a little. And you can always add a little mass, which will reduce your altitude and speed a lot. So the trick is basically that you know which booster you need to get above the requested altitude and speed. And then you do these little things to reduce it down to the exact number you want.

But after you get practiced a bit at it, you can get it right in just a couple launches.

 

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Welcome to the forums!

Mr @bewing failed to extend this courtesy so, sadly, he will be fined and chastised at the next staff meeting. ;.;

Of course, everything he said was right. I know you didn't want a "trial and error" answer though, so I'll just offer an alternative: if you're grabbing testing contracts to make money, you can just accept the ones that say test "at the launchpad", "splashed down", or "landed at Kerbin". Not much to work on with those. The launchpad ones are an especially easy way to make some quick cash in the early game. As an added bonus, if you take fewer of a certain contract, they'll be offered less often. And vice versa if you accept certain contracts, they'll be offered more often.

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Actually the maths is not particularly difficult http://www.rocketmime.com/rockets/qref.html *

However finding the correct values for drag coefficient and air density is not trivial. Also, due imprecisions both in the calculation and in flight, you may not reach the predicted altitude.

 

* pretty often Rocket/Plane modellers offer some knowledge we can use in KSP. If you are the type that like to know why/how something works use that source to your advantage.

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I tend to decline such contracts when both speed and altitude requirements don't usually uccur during launches (I always do part testing along with other missions, not on its own).

sometimes I choose a slightly different ascent profile to meet the requirements, but they shouldn't be too far off. With some expierience, you'll have a good feeling for which contract to choose.

 

So ... I advise you to go on with trial and error, but be careful which contract you accept.

Edited by Physics Student
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As others have mentioned, after inadvertently blundering into a couple of those very picky contracts early in my career game, I avoid them now like the space plague. Anything that says "test (or collect science) in the atmosphere" etc. I steer a wide path around.

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1 hour ago, FloppyRocket said:

As others have mentioned, after inadvertently blundering into a couple of those very picky contracts early in my career game, I avoid them now like the space plague. Anything that says "test (or collect science) in the atmosphere" etc. I steer a wide path around.

Yup.  I'll take contracts at the pad, I'll take some contracts landed, I'll take some contracts splashed down (stick it on a rover and drive into the sea beyond the runway.)  Otherwise, if it's atmosphere it's out of the question and most space-based contracts are also pretty bad.

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Dont forget to turn your decline penalty to zero.  Giving up after taking a contract I can see the need for reputation loss, but not for declining in the first place.  

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1 hour ago, klesh said:

Dont forget to turn your decline penalty to zero.  Giving up after taking a contract I can see the need for reputation loss, but not for declining in the first place.  

Maybe I'm overthinking it but, If you are pressing the agencies for "something else" instead of the projects they current have,  its understandable the agencies conclude you are not as reliable they thought . Nonetheless the agencies recognize the opportunity and offer some lower profile projects, (which may not yet had received the same attention the contract you declined did). Its not that the agencies consider you incapable, but you gave then signs of not sharing the same vision.

Anyway its just a matter of perspective, if you think there is no reason to reputation loss turn it off.

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On 5/5/2017 at 4:00 PM, Spricigo said:

Maybe I'm overthinking it but, If you are pressing the agencies for "something else" instead of the projects they current have,  its understandable the agencies conclude you are not as reliable they thought . Nonetheless the agencies recognize the opportunity and offer some lower profile projects, (which may not yet had received the same attention the contract you declined did). Its not that the agencies consider you incapable, but you gave then signs of not sharing the same vision.

Spricigo,

 KSP already accounts for this. If you accept parts testing contracts, it will submit more parts testing contracts. If you decline or ignore them it will offer less. I rarely accept test contracts. They just don't pay well for the hassle involved. I go for tourists, rescues, and satellites. Much easier money. Especially rescues, which reward you with trained kerbonauts in addition to heaps of cash.

Best,
-Slashy

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@GoSlash27 you are correct. However my point was about why,  in my rationalization,  the reputation loss for declining a contract make sense.

Notice,  I didn't said it's the best way for the contract system work...Jbust it make sense. 

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6 hours ago, Spricigo said:

@GoSlash27 you are correct. However my point was about why,  in my rationalization,  the reputation loss for declining a contract make sense.

Notice,  I didn't said it's the best way for the contract system work...Jbust it make sense. 

Spricigo,

 Roger that. I avoid the whole thing by simply ignoring contracts I don't want. I never decline them, I just let them expire.

Best,
-Slashy

Edited by GoSlash27
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  • 7 months later...
On 5/2/2017 at 12:08 PM, xRDK said:

I am wondering is there an easy way to calculate what speed your ship will be doing at altitude X with certain settings?

That is quite literally rocket science :D  There's loads of rough guesses and approximations I could throw at you - estimate from gravitational energy, estimate from newtonian mechanics - but at the end of the day it's probably easier to cheat with liquid-fueled engines and the occasional spaceplane.  You can make a "spaceplane" out of junos and a swivel.  It won't make it to orbit, but it can beat 62,000m.

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