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Orbital map and ETA calculations  

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XenonS
(@xenons)
Warrant Officer Registered
Joined: 4 years ago
Posts: 406
October 20, 2020 15:16  

I have paused with this game a long time and highly enjoy all the marvelous improvements now, especially the new mission types.

I have a question reguarding the orbital map and the 5 setting tabs you can change on the upper right. As I understand you can plan a maneuver by changing these numbers, I have tried hard making reasonable entries but I fail to get any ETA for my destination. Basically I must accelerate my ship until the middle of the destination then turn my ship around. I would like to know the ETA to reach destination or the middle point. How must I change the values exactly to get it right? Will this also work if I'm not flying, when docked in a station, can I plan ahead with the orbital map to get an estimated flying time to a target?

 

Thank you very much for a feedback!

XenonS


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ffefun
(@ffefun)
Crewman Registered
Joined: 1 month ago
Posts: 3
October 27, 2020 18:06  

Hi,

I have a very similar question to yours. Can someone please help and give detailed description on how to use the orbital map when planning a maneuver? I've read carefully an entry from pioneerwiki "How to fly without autopilot" and followed it. There is a vague statement saying:

"Important to note, that this method will not work on some cases, because it wasn't intended for this kind of planning, and these directions aren't always sufficient"

This is fine but please give more details. What are the limitations? Why this method will not always work? Would this work for a SAR mission? In my SAR mission I tried to reach a floating ship that had very unstable trajectory and was able to precisely set my projected trajectory to meet that ship. After following the wiki, accelerating towards the maneuver prograde for the given time I ended up far away from expected position. I tried this couple of time changing time of acceleration to what the wiki says - i.e. "at ETA time" which to me is probably a mistake. All and all after several tries I gave up and decided to register here and ask the question :-).

I really enjoy the game and appreciate it's still in beta but please help and give more information.

To answer the question above:

My understanding is the ETA is not precisely calculated by the program. It's an estimated time when you meet the target (assumed visually by yourself when your ship and the target are close to each other) and it is shown on the orbital map as the "time point" in the bottom left corner after you move forward the time manually using the time arrow buttons on the bottom right.

Also, I understand that a middle of maneuver burn should be used as it says on the tin, i.e. if your calculated time of maneuver burn is 5min, you start your maneuver 2.5min before the middle of maneuver burn and finish it 2.5min after it.

Please, all experts of the Pioneer correct me here if my understanding is correct.

Thanks

EDIT: Actually my SAR mission's target (a floating ship) has a very unstable RELATIVE trajectory. However, when looking at it from the system's center sun it is almost completely steady in time compared to other celestial bodies orbiting and moving around. I believe it might be a mistake, as no such motionless bodies can physically exist in any system.

EDIT2: I was wrong, the target wasn't actually stable. It's just its future trajectory available on the orbital map indicated falsely its stability. In game, as the time passed, it was behaving correctly.

This post was modified 1 month ago by ffefun
This post was modified 4 weeks ago by ffefun

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nozmajner
(@nozmajner)
Warrant Officer Registered
Joined: 4 years ago
Posts: 266
October 29, 2020 04:57  

Sadly the maneuver planner isn't really suited for that kind of accelerate halfway, then decelerate transfers. Even though it calculates burn time, it assumes in the orbit calculations that the change in velocity is instant. And it won't work while docked, because it needs a current orbit for that.

You could try about halving your deltaV (accessible in the F2 infoview screen), enter that much in the planner, but it will be quite finicky (I just tried).
You also can advance and rewind time in the orbit map to check orbits, you don't need to time accelerate for that.
The flight UI will then tell you the burn time, but you constantly need to cross-reference with that, but since our ships are so strong, at a longer trip you hit half of your deltaV much sooner than the half-point of your distance. For that reason, and because the ships aren't constant acceleration, because of the changing mass while you burn your fuel, the brachistocronne equation will only give a rough estimate of travel time as well.
(yet, I'm working on a rebalance that mostly fixes accelerations, exactly because it easier to fly that way, and to avoit overly strong final acceleration values, like 20ish Gs).

But: we do have an UI for these kinds of transfers in the flight HUD. It won't give you the travel time, but will tell you when you need to flip and start decelerating, and also shows your deltaV against your current speed, so you won't run out of fuel.


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XenonS
(@xenons)
Warrant Officer Registered
Joined: 4 years ago
Posts: 406
October 29, 2020 14:39  

Thank you very much nozmajner for your response and details. I have read the link before posting and figured out that you need to be in the 'Coasting' phase for these 5 tabs to make any sense, despite of that I was never able to plan a maneuver with them, but the flying UI in the Front View gives all details about *when* to turn your ship arround, but it would be very fine to have an anticipated ETA like for these formulas (see below).

Very long ago I have made a personal help file for Frontier Elite II as for planing ETAs on long travels in order to know wether I can accept delivery missions after hyperdriving. Here the excerb:

 

----------------------------------------------------

  1. ETA CALCULATION (Estimated Arrival Time)

For most missions it’s important to accomplish them in time and therefore it’s crucial to know when one could expect to a) arrive in a system and b) to know the necessary time to travel within the system to a destination.  With a constant acceleration and using the main engines to decelerate, here are the precise equations:

v_tp = sqrt(a d);     t = 2 sqrt(d/a);    

v_tp     =  velocity at turning point d/2 in meters/second

a          = acceleration      9,81g x ship main engine acceleration (in g)       

d          =  total distance  in meters           

t           =  time for destination  in seconds

The formulas above provide precise calculations, but in practice one should calculate unpredictable events, like attacks and flight path deviations designed to avoid attacks etc.

The lists below give MINIMUM SAFE VALUES which are not 100% accurate, but include such unpredictable “time losses”, adding a 15% tolerance and cutting the result to a higher value.

As every ship has different acceleration capabilities, be sure to refer to the correct ship.

 

EAGLE MK I (a=25.2g) 247,212

 

Distance in AU

Travel time in days/hours

Velocity at turning point in Km/s

5

1d 12h

13598

10

2d 2h

19230

15

2d 13h

23552

20

2d 23h

27196

25

3d 7h

30406

30

3d 15h

33308

40

4d 4h

38461

50

4d 16h

43001

60

5d 2h

47105

70

5d 11h

50080

100

6d 14h

60813

150

8d 1h

74481

200

9d 7h

86003

300

11d 9h

105332

400

13d 3h

121627

500

14d 16h

135983

 

  1. GENERAL NAVIGATION PROCEDURE

The general procedure is: look at the distance to travel and remeber HALF that distance. Accelerate until arrived at half the distance, then make your ship a 180° turn and set the speed to 0. You should come to a halt a bit before your destination.

Within a body’s orbit, I recommend a speed of 30 km/s and a descent speed of 20000 km/h. This descent speed gives you enough time to brake (pointing towards the sky) as soon as you get an altitude reading (from 60000 m downwards).

  1. FUEL CONSUMPTION

 

The Hyperdrive fuel consumption is: (hyperdrive class)^2 = tons of fuel for maximum drive range in 7 days.

 

For less than the maximum drive range, the consumption and the time are linearly less.

 

Within a system, 1 ton of fuel is sufficient for 50-70 AU.

------------------------------------------------------------------------------

The numbers for the hyperdrive classes and fuel consumption are of course different now in Pioneer, also the introduction of 'Delta v' makes Coasting much more frequent and the formulas need to be adapted.

 

 

This post was modified 4 weeks ago by XenonS

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nozmajner
(@nozmajner)
Warrant Officer Registered
Joined: 4 years ago
Posts: 266
October 30, 2020 07:24  

Yeah, such a table might not work as is. I was thinking about doing something similar to that, but my limited math knowledge provided a nice brick wall I might want to try to surmount again sometimes.

On the other hand I did a bunch of thinking about such planner tool for the orbit map a while ago, and it would sure be nice to have one for such transfers. You setting up a route, even with multiple burns and such, and the autopliot would execute it. But note that this is just an idea of an artist who dabbles in the design and thinks about the UI, coding it is where the meat of the work would lie.


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