Chapman Challenge

[atuhalpa]

Piper, is it kosher to use a Delta4HV upgrade with a fregat to do the advanced challenge?

I need all the help I can get......................

[Piper]

Quote:

Originally Posted by atuhalpa

 Piper, is it kosher to use a Delta4HV upgrade with a fregat to do the advanced challenge?

I need all the help I can get......................

Sure, but I'll tell you right now that you don't need that much dV to complete it. All you need is enough dV to get to Jupiter with a basic Hohmann transfer, find a leading trojan with an inclination between about 30 and 40 degrees, and time your depature so that when you do a fly-by Jupiter you do it at about the same time you cross the trojan's node. I posted a scenario that gets you to 2001 DZ3 that has an encounter veloctiy of about 1200m/s (iirc). Here is another scenario for Meges, a larger trojan (about 50km in diameter), and one that gave me an encounter velocity of only about 950m/s. The scenario uses an Atlas V 552, but you can of course change it to anything you like.

BEGIN_DESC
Launch Chapman 14, onboard a Atlas 552, to the Jupiter Trojan "Meges."  Swing-by Jupiter to get to it and put yourself into orbit around it.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 58131.7
END_ENVIRONMENT

BEGIN_FOCUS
  Ship AtlasV
END_FOCUS

BEGIN_CAMERA
  TARGET AtlasV
  MODE Extern
  POS 2.89 0.74 -110.96
  TRACKMODE TargetRelative
  FOV 50.00
END_CAMERA

BEGIN_HUD
  TYPE Surface
END_HUD

BEGIN_MFD Left
  TYPE User
  MODE TransX
  Ship  AtlasV
  FNumber 5
  Int 1
  Orbit True
  Vector  396451.035217 5007999.44854 -3918269.51067
  Vector  407.451098393 -11.5045207652 26.5218550764
  Double  3.98600439969e+014
  Double  56548.006728
  Handle Earth
  Handle NULL
  Handle NULL
Select Target
 0 Escape
Autoplan
0 0
Plan type
0 0
Plan
0 1
Plan
0 0
Plan
0 0
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 0
Prograde vel.
 0  0
Man. date
 0  56548.006539
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
Pe Distance
 0  7645212
Ej Orientation
 0  0
Equatorial view
0 0
Finvars
  Finish BaseFunction
  Int 2
  Orbit False
  Handle Sun
  Handle Earth
  Handle Jupiter
Select Target
 0 Jupiter
Autoplan
0 0
Plan type
0 2
Plan
0 0
Plan
0 0
Plan
0 1
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 1
Prograde vel.
 0  0
Man. date
 0  56548.0067283
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
Prograde vel.
 1  8760.57269615
Eject date
 1  58132.9502884
Outward vel.
 1  73
Ch. plane vel.
 0  -770
Finvars
  Finish BaseFunction
  Int 4
  Orbit True
  Vector  340743866703 -7890259262.32 334176971692
  Vector  -4709.35265714 162.83282363 -4633.64143142
  Double  1.26686534397e+017
  Double  58110.8118354
  Handle Jupiter
  Handle NULL
  Handle NULL
Select Target
 0 Escape
Autoplan
0 0
Plan type
0 1
Plan
0 0
Plan
0 1
Plan
0 0
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 0
Prograde vel.
 0  0
Man. date
 0  56548.006704
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
View Orbit
0 0
Finvars
  Finish BaseFunction
  Int 3
  Orbit True
  Vector  154573448826 -8025716674.09 -769844088380
  Vector  10264.5498094 -6403.91442202 2855.54194119
  Double  1.32839126489e+020
  Double  58929.7627551
  Handle Sun
  Handle Jupiter
  Handle Meges
Select Target
 0 Meges
Autoplan
0 0
Plan type
0 2
Plan
0 0
Plan
0 0
Plan
0 2
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 0
Prograde vel.
 0  0
Man. date
 0  56548.0067283
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 1
Graph projection
0 0
Scale to view
0 2
Advanced
0 0
Velocity.
 0  0
Outward angle
 3  -0.0284314135146
Inc. angle
 4  1.92229830777
Inherit Vel.
0 0
Eject date
 0  58929.7627551
Finvars
  Finish BaseFunction
  Int 5
  Orbit False
  Handle Meges
  Handle NULL
  Handle NULL
Select Target
 0 None
Autoplan
0 0
Plan type
0 1
Plan
0 0
Plan
0 2
Plan
0 0
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 1
Prograde vel.
 0  0
Man. date
 0  56548.0066945
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
Draw Base
0 0
Finvars
  Finish BaseFunction
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE TransX
END_MFD

BEGIN_SHIPS
AtlasV:MultistageMultistage2
  STATUS Landed Earth
  BASE LC41:1
  HEADING 90.00
  FUEL 1.000
  CONFIG_FILE ConfigATLASV500_SeriesDual_Engine_CentaurShort_FairingAV552_Chapman.ini
  CONFIGURATION 0
  CURRENT_BOOSTER 1
  CURRENT_STAGE 1
  CURRENT_PAYLOAD 1
  FAIRING 1
END
END_SHIPS

-----Post Added-----


The advanced challenge seems to be a bit too difficult for most people, so I'm changing the advanced challenge slightly, you no longer need to orbit the Jupiter Trojan, just fly-by it (after a fly-by of Jupiter), and the bonus is to orbit it. I'm also extending the challenge until the end of February.

Modified Advanced Challenge:
HTML clipboard

• Mission Goal: Swing-by Jupiter, then fly-by any Jupiter Trojan asteroid
  • Bonus: Orbit the Trojan instead of flying-by it
• Spacecraft: Chapman Outer
• Launch Location: Your Choice
• Launch Vehicle: Your Choice
• Launch Window: 55562.0000 and onward - Anytime after January 1st 2011
• Required Add-ons:
  • MPC Database Viewer/Exporter

    MPC Database Viewer/Exporter

    by Joseph Morgan

Also to assist those searching for usable trojans to fly-by, I've created a zip file with 35 possible candidates for completing the challenge with the bonus (I've only tested Meges out of the bunch, but most of the others should be good too):

Jupiter Trojans

As for the Regular Challenge, I realized that when I tested it, the ChapmanInner1 I was using was slightly different then the one I released. Add this to the beginning of your ChapmanInner1.ini:

[AERODYNAMICS]
RUDDER_ATTACK=(0,0,0)
RUDDER_AREA=0.0001 ; no rudder
RUDDER_LIFT=0
AILERON_AREA=0.0001 ; no aileron
AILERON_LIFT=0
AILERON_ATTACK=(0,0,0)
ELEVATOR_AREA=0.0001 ; no elevator
ELEVATOR_LIFT=0
ELEVATOR_ATTACK=(0,0,0)
ELEVATOR_TRIM_AREA=0.0001
ELEVATOR_TRIM_LIFT=0
ELEVATOR_TRIM_ATTACK=(0,0,0)
RUDDER_TRIM_ATTACK=(0,0,0)
RUDDER_TRIM_AREA=0.0001 ; no rudder trim
RUDDER_TRIM_LIFT=0
FLAPS_ATTACK=(0,0,0)
FLAPS_AREA=0.0001 ; no flaps
FLAPS_LIFT=0
VAIRFOIL_ATTACK=(0,0,-0.2)
VAIRFOIL_CHORD=1.4
VAIRFOIL_AREA=4.2
VAIRFOIL_ASPECT=2.14
VAIRFOIL_WAVE_DRAG=0.2
VAIRFOIL_CD0=0.2
HAIRFOIL_ATTACK=(0,0,-0.2)
HAIRFOIL_CHORD=1.4
HAIRFOIL_AREA=4.2
HAIRFOIL_ASPECT=2.14
HAIRFOIL_WAVE_DRAG=0.2
HAIRFOIL_CD0=0.2
HAIRFOIL_LIFT_1=(-180,0)
HAIRFOIL_LIFT_2=(0,0)
HAIRFOIL_LIFT_3=(180,0)
VAIRFOIL_LIFT_1=(-180,0,0)
VAIRFOIL_LIFT_2=(0,0,0)
VAIRFOIL_LIFT_3=(180,0,0)

This should correct any chaotic tumbling when aerobraking.

[Whatu]

Ok, I'm approaching venus now, though my ejection burn wasnt exactly perfect...

So, for aerobraking...

What are the structural limits of the probe? How much g's and how much dynamic pressure is recommended?

Its possible to slow down enough to be captured in the first pass?

I want to finish this one and try to flybly a trojan Thanks

[Piper]

Quote:

Originally Posted by Whatu

 Ok, I'm approaching venus now, though my ejection burn wasnt exactly perfect...

So, for aerobraking...

What are the structural limits of the probe? How much g's and how much dynamic pressure is recommended?

In real-life, the probe probably wouldn't do anything more then 0.01gs, and just do dozens or hundreds of aerobrakes.

Obviously, I don't expect people to do that many, but you should limit it to no greater then 0.5gs.

Quote:

Originally Posted by Whatu

 Its possible to slow down enough to be captured in the first pass?

No, the probe would burn up without a heatshield.

Quote:

Originally Posted by Whatu

 I want to finish this one and try to flybly a trojan Thanks

Good luck!

[atuhalpa]

Wow! Piper I just emulated the initial transx setup and ejection burn for your Trojan Meges encounter. I believe I will be able to duplicate your feat, no doubt with many saves and "do overs", but I must commend you on your concepts. Maybe all seasoned Orbiter afficianados know what you have shown me with the meges setup, but you certainly expanded my understanding of what a flyby can accomplish depending on proximity, inclination and velocity! I will post my results, but must withdraw from formal competition in the advanced challenge. Thanks for your "puzzles".

[atuhalpa]

Piper I completed the advanced mission, but only because you posted your flight plan..............I learned a lot and enjoyed all of the concepts involved completing this challenge.

Delta 4 heavy, fregat, Kourou, Launch 58132

Thanks for the challenge................

[Piper]

Quote:

Originally Posted by atuhalpa

 Piper I completed the advanced mission, but only because you posted your flight plan..............I learned a lot and enjoyed all of the concepts involved completing this challenge.

Delta 4 heavy, fregat, Kourou, Launch 58132

Thanks for the challenge................

Finally! Somebody who has completed the advanced challenge! Now let's see if someone can get into orbit around a trojan.

By the way, in case anybody has been following the competition, and hasn't seen, I've released a newer version of the

Chapman probes

Chapman probes

. It fixes the problem people were having with aerobraking with a Chapman probe, and fixes the incorrect weights in the given scenario files.

[atuhalpa]

Piper, that is a ChapmanOuter in orbit around Meges. Here is another screen shot. I guess I didn't make it clear in my post. I must reiterate that had it not been for the posting of your Meges flight plan I would still be floundering. Once I studied your plan the light came on and the rest was basically routine.

I have archived every critical juncture in the mission if you want more specific data.

[Piper]

Quote:

Originally Posted by atuhalpa

 Piper, that is a ChapmanOuter in orbit around Meges. Here is another screen shot. I guess I didn't make it clear in my post. I must reiterate that had it not been for the posting of your Meges flight plan I would still be floundering. Once I studied your plan the light came on and the rest was basically routine.

I have archived every critical juncture in the mission if you want more specific data.

Sorry, I didn't realize that those were from orbit, even better!

[atuhalpa]

For my own edification I am going to orbit a Trojan using my own flight plan and the MPC viewer. Then and only then will I feel I have truly completed the challenge.

[atuhalpa]

Yeah! Piper I did it all on my own this time. My inclination change for 1996 RJ wasn't as good as it should have been but I had the Fregat along for the ride so I had plenty of Dv. I launched a D4HV from Kourou. After Jupiter encounter and inclination change I crossed 1996 RJ's node about a quarter of the way around, so it cost alot to align the 5 degrees I was off. Syncing cost me about the same as I did sync adjustments frequently. In the end I was 343M distant and had to adjust for a 976 Rvel. I used IMFD's velocity match to close and sync 3 times then I backed into orbit with 60% fuel left in the Chapman.

All in all a most enjoyable and educational experience.

[Piper]

Quote:

Originally Posted by atuhalpa

 Yeah! Piper I did it all on my own this time. My inclination change for 1996 RJ wasn't as good as it should have been but I had the Fregat along for the ride so I had plenty of Dv. I launched a D4HV from Kourou. After Jupiter encounter and inclination change I crossed 1996 RJ's node about a quarter of the way around, so it cost alot to align the 5 degrees I was off. Syncing cost me about the same as I did sync adjustments frequently. In the end I was 343M distant and had to adjust for a 976 Rvel. I used IMFD's velocity match to close and sync 3 times then I backed into orbit with 60% fuel left in the Chapman.

All in all a most enjoyable and educational experience.

Yet again, excellent work! I have to say, I love seeing people complete these challenges, it's nice to know that I'm not the only person who can do this stuff.


By the way, is there anybody else still working on any of the current challenges? If there isn't, I'll bring this one to a close at the end of the month, and start the next one.

Also, how does people feel about using low-thrust engines (ie. ion thrusters like Smart-1)? I'm currently designing a fourth (and maybe fifth) version of Chapman that uses a Hall effect thruster instead of a liquid propellant engine, and if there are enough people out there that are experienced on doing a challenge like that I'll do an advanced challenge with it. It would probably be something straight forward like getting into orbit around Ceres (which I actually did last night with it , after a beautiful fly-by of Mars). Currently the design has a total dV of about 28,000m/s (about 10 times that of the other Chapmans). However that may change as I try and find the most appropriate settings.

Speaking of the next challenges, does anybody have any recomendations? I have some of my own ideas, but I would love to hear some other ones.

[astrosammy]

Maybe some challenges with reaching different Lagrange points? Or bring two probes up at once, let them arrive at an planet at different times and let them rendezvouz each other.

[Whatu]

Venus challenge:

Finally completed it!

I launched the Chapman in an Ariane 5 ECA from Cape Canaveral, but I didnt take a pic of it, sorry.
With about 98% fuel of upper stage, I executed my escape plan (transx):

hm.. I need to learn a little bit more in this area, transx approximation was 12 M.. way off.

Necessary correction (IMFD from now on):


After capture burn:


One of the aerobrakes:

I did the first aerobrake at ~0.01 g's to get the taste of it, and after that I did 5 or 6 ~0.4 g's ones.

Last aerobrake:

To finally circularize at ~550km. 45º ecliptic inclination.


So, thanks to you Piper for providing such an enjoyable and educative challenge.

I will try to at least get to a Trojan, but not for this challenge, because this can take ages!

Looking forward to the new challenges and maybe a little tutorial on low-trust navigation.

[atuhalpa]

Wow Piper, I just went to your website for the first time. I didn't know how much you had contributed till I went there. I must say I am awestricken by how much you have done regarding all aspects of Orbiter. I feel like a toddler after seeing your accomplishments. By the way thanks for the Chapman Challenge II recognition.

The only negative aspect of my involvement in the Challenge and Orbiter is that my live in girlfriend has threatened to leave me if I spend much more time hunkered down in front of the transx console grunting 'No!' back at her when she asks me if I coming to bed yet .

I guess I'll just have to get HER interested in Orbiter as much as I am.