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Newbie help with escape trajectory


jonpfl

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So I can getting into orbit on occasion (but not at 3.4k but usually around 4k) and now one of my contracts is escape trajectory.  I have no clue how to do it?  I read I am supposed to get into orbit but once I do, I burn my engines to try and straighten the line out but always run out of fuel.  How?

Also, I have a space capsule in orbit with two passengers in it, is it stuck there until I rescue it?  The contract is still lit up.

Thx
jonpfl

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An escape trajectory is one that leaves the SOI of the place you're taking off from. Just take off like you're going to orbit but then keep burning the engine. If your ship doesn't have enough dV, add a stage under what you've got so far. 

Yes, the capsule is stuck there. You could eliminate the flight from the tracking center, but that would kill the crew. You'll have to send something up to rescue them. 

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6 hours ago, Vanamonde said:

An escape trajectory is one that leaves the SOI of the place you're taking off from. Just take off like you're going to orbit but then keep burning the engine. If your ship doesn't have enough dV, add a stage under what you've got so far. 

Yes, the capsule is stuck there. You could eliminate the flight from the tracking center, but that would kill the crew. You'll have to send something up to rescue them. 

I assume that means fly parallel to the ground to get into orbit but keep going until you are out of the SOI, correct?  I think I read that your elliptical orbit should turn into a straight line, right?

I keep having problems of running out of fuel, I am wondering if I am doing something fundamentally wrong since I have almost 4k of delta V and barely get into orbit.  Other have helped me to get into orbit but they told me I should be able to do it with 3.4k delta V.

When I get home, I am going to post a pic of my ship and maybe you (or someone) can comment and give me tips.  

Thx
jonpfl

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The fuel efficient way is to go for a near circular at start. And than do the escape birn on your lowest orbital point (Periapsis). And one additional escape burn stage do not realy hurt you. Take a vacuum optimased engine for it and go for full burn :wink:

Funny Kabooms 

Urses 

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2 hours ago, Urses said:

The fuel efficient way is to go for a near circular at start. And than do the escape birn on your lowest orbital point (Periapsis). And one additional escape burn stage do not realy hurt you. Take a vacuum optimased engine for it and go for full burn :wink:

Funny Kabooms 

Urses 

Ok, I will try this when I get home and also post a pic of my rocket.

I am in career mode and thus might not have the greatest engines to do this.

Thx
jonpfl

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  • 4 weeks later...
On 5/18/2017 at 8:26 PM, jonpfl said:

 

On 5/18/2017 at 1:34 PM, Vanamonde said:

An escape trajectory is one that leaves the SOI of the place you're taking off from. Just take off like you're going to orbit but then keep burning the engine. If your ship doesn't have enough dV, add a stage under what you've got so far. 

Yes, the capsule is stuck there. You could eliminate the flight from the tracking center, but that would kill the crew. You'll have to send something up to rescue them. 

I assume that means fly parallel to the ground to get into orbit but keep going until you are out of the SOI, correct?  I think I read that your elliptical orbit should turn into a straight line, right?

I keep having problems of running out of fuel, I am wondering if I am doing something fundamentally wrong since I have almost 4k of delta V and barely get into orbit.  Other have helped me to get into orbit but they told me I should be able to do it with 3.4k delta V.

 

Hmm, in theory yes but people forget about all the inefficiencies getting to orbit on an atmospheric body to begin with, as you've already noticed from practical experience. It is possible to actually get into orbit for 2800-3100dV when you get really good at things. That's ~900dV gone in your case.

Perhaps go semi-ballistic instead. Launch, tip 5-10 degrees east. Proceed at full thrust. Set SAS prograde. The higher TWR you have, the more aggresive you can let it tip till well past 45% at 20 km. Past 30 km, you might consider actively forcing the nose down. Total dV to escape trajectory ~4000-4200dV.

It can be done before getting the BACC Solid Rocket Boosters (SRBs) but using the BACCs and a Reliant or two (depends on your payload) will get you there. High TWR is your friend.

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