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Old 03-25-2013, 02:02 AM   #31
Bloodworth
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I missed out the last 2 times. I can fly e2m (transX) and do mars landings. COunt me in.
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Old 03-25-2013, 02:11 AM   #32
dgatsoulis
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As suspected (by garyw), the Dragons are not fit for Martian EDL. Both tests resulted in a crash on the surface with ~70 m/s vertical speed.
The main parachutes do not provide enough drag, due to the thin atmosphere.

Here is the scenario with both manned(7) and cargo Dragons on a 200x200km orbit around Mars, if anyone else wants to give it a try. (Perhaps there is a procedure for the reentry that I am not aware of? )

The manned has a full crew of 7, fuel 15%.
The cargo has no cargo attached, fuel 15%.

Code:
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 58620.820628
;58620.7984056282
END_ENVIRONMENT

BEGIN_FOCUS
  Ship Dragon_Manned
END_FOCUS

BEGIN_CAMERA
  TARGET Dragon_Cargo
  MODE Extern
  POS 7.88 -123.46 31.03
  TRACKMODE TargetRelative
  FOV 60.00
END_CAMERA

BEGIN_HUD
  TYPE Orbit
  REF Mars
END_HUD

BEGIN_MFD Left
  TYPE Orbit
  PROJ Frame
  FRAME Ecliptic
  ALT
  REF Mars
END_MFD

BEGIN_MFD Right
  TYPE Docking
  NAV 0
END_MFD

BEGIN_SHIPS
Dragon_Cargo:SpaceX\DragonC
  CFG 1 25679448.5444
  STATUS Orbiting Mars
  RPOS 494170.66 -30.91 -3555744.78
  RVEL 3421.124 -0.250 475.461
  AROT 179.97 82.34 179.97
  RCSMODE 2
  AFCMODE 7
  PRPLEVEL 0:0.15
  NAVFREQ 0 0
  CONFIG 3 1 0
  ANIM0 0 0.0000
  UCGO @@0,1,0,0,@@1,1,0,0,@@2,1,0,0,@@3,1,0,0,@@4,1,0,0,@@5,1,0,0,@@6,1,0,0,@@7,1,0,0,
  TRUNK 0
END
Dragon_Manned:SpaceX\DragonM
  STATUS Orbiting Mars
  RPOS 494170.66 -24.63 -3555744.78
  RVEL 3421.124 -0.258 475.461
  AROT 179.97 82.35 179.97
  RCSMODE 2
  AFCMODE 7
  PRPLEVEL 0:0.15
  NAVFREQ 0 0
  CONFIG 3 1 0
  ANIM0 0 0.0000
  UCGO @@0,1,0,0,@@1,1,0,0,@@2,1,0,0,@@3,1,0,0,@@4,1,0,0,@@5,1,0,0,@@6,1,0,0,@@7,1,0,0,
  TRUNK 0
  ANIM1 0 0.0000
  ANIM2 0 0.0000
  CFG 0 1 0 1 1 0 1 10483560
  PARAMS 83.9815 14.0000 1.4000 14.2000 1.0000 24240750.0000 -2500.0000
  UMMUCREW Capt-dgat-35-68-85
  UMMUCREW Sec-Jim-28-65-75
  UMMUCREW Crew-John-26-60-89
  UMMUCREW Doc-Jenna-32-65-60
  UMMUCREW Vip-jack-45-65-70
  UMMUCREW Crew-Vera-25-58-55
  UMMUCREW SEC-Paul-48-72-88
END
END_SHIPS

BEGIN_ExtMFD
END
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Old 03-25-2013, 02:19 AM   #33
MaverickSawyer
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Huh... so the 'chutes DO deploy. That's a plus.
Did you fire the engines at max during parachute descent? I think that would make a slight difference...
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Old 03-25-2013, 02:20 AM   #34
Pipcard
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What about this?
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Old 03-25-2013, 02:24 AM   #35
MaverickSawyer
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That's right, the Dragon M and L have propulsive landing. But that doesn't solve the cargo landing issue...
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Old 03-25-2013, 02:29 AM   #36
dgatsoulis
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Yes, I did use the engines. But I am not very familiar with glider's Dragon, that's why I posted the scenario if anyone else wants to try.

The drogue chute deployed at ~8 km, followed by the main chutes shortly after.

I loaded the Dragons only with 15% fuel, to keep them light during the reentry, but with enough fuel to use the engines. The orientation of the spacecrafts during the reentry was "heads-down", so the panel that the chutes come out of was "right side up".
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Old 03-25-2013, 03:14 AM   #37
MaverickSawyer
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I'll take it for a spin next week.
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Old 03-25-2013, 03:47 AM   #38
mojoey
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Were you using the 'in-orbit' engines, or the LES motors? The LES motors (as shown in the CG video above) are way more powerful.

---------- Post added at 08:47 PM ---------- Previous post was at 08:44 PM ----------

We could, use Antares if Dragon doesn't work. Else we might have to use the DG-IV.
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Old 03-25-2013, 04:00 AM   #39
MaverickSawyer
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I think the issue now is in the fact that the Cargo Dragon doesn't have the propulsive landing system.
However, if memory serves, the crewed Dragons do have a small UCGO allotment built in (either four or six sticks out in my head) So, if the Cargo Dragon doesn't have a larger UCGO capacity, it makes no sense to run it to Mars. We could divide the landing party between two "landers" and have a slightly heavier cargo capacity (in theory), or we can now double our landing party size.
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Old 03-25-2013, 09:10 AM   #40
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Quote:
Originally Posted by dgatsoulis View Post
 As suspected (by garyw), the Dragons are not fit for Martian EDL. Both tests resulted in a crash on the surface with ~70 m/s vertical speed.
The main parachutes do not provide enough drag, due to the thin atmosphere.
Yup, that was my concern. Thanks for the test.

Quote:
Originally Posted by MaverickSawyer View Post
 Huh... so the 'chutes DO deploy. That's a plus.
No reason they shouldn't as the chutes will be triggered on either altitude or speed - probably altitude.

Quote:
Originally Posted by MaverickSawyer View Post
 Did you fire the engines at max during parachute descent? I think that would make a slight difference...
I can't see that helping much at all. What you need are bigger chutes deployed earlier - somewhere around Mach 2 (with reference to Mars). The bigger the chute the more air you trap so the slower the decent.

Either that or you'll have to UCD/Glue/attach/velcro some sort of 'soft' landing thruster like used on Soyuz.
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Old 03-25-2013, 09:46 AM   #41
Athena
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Quote:
Originally Posted by garyw View Post
 Either that or you'll have to UCD/Glue/attach/velcro some sort of 'soft' landing thruster like used on Soyuz.
You *could* use the Antares LR instead...it has brake engines and landing gear...

Last edited by Athena; 03-25-2013 at 09:48 AM.
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Old 03-25-2013, 09:48 AM   #42
IronRain
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Quote:
Originally Posted by Athena View Post
 I was wondering would the Antares LR make it to the surface? it has brake engines and landing gear...
I think you still have the chute problem. You won't slow down enough before you reach the surface.
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Old 03-25-2013, 10:02 AM   #43
Athena
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Hmmm, your right about the chute...deployed it around 1.3km, slowed down but not really much, used the brake engines and maintained a vertical velocity of around 18-26 meters per second....hit the surface with the capsule going at around 22 m/s...rough landing...
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Old 03-25-2013, 10:13 AM   #44
dgatsoulis
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Quote:
Originally Posted by mojoey View Post
 Were you using the 'in-orbit' engines, or the LES motors? The LES motors (as shown in the CG video above) are way more powerful.

I did use the LES engines in the manned Dragon. Well... in the sense that I had the button for the Propulsive Landing Mode pressed and setup the fuel for a landing. The system is automatic and no user input is required (or permitted).




From the manual:
Quote:
All versions of Dragon, except the cargo version, can land on solid ground. To do so, you should select the ground landing mode by pressing G or by pushing a button in the VC. The parachute will be jettisoned at 200 m altitude, then capsule will be rotated by LES thrusters, landing gears will be deployed, and after that, capsule will be decelerated to 0 vertical speed and landed safely. Ground landing doesn’t require any user action except selection of propulsive landing mode. Propulsive landing require at least 350 kg of fuel.
At the alt of 200m, where the PLM is supposed to run, the Dragon was plummeting towards the surface at ~70 m/s. No time to do anything. The engines didn't even fire.
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Old 03-25-2013, 10:13 AM   #45
garyw
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Quote:
Originally Posted by Athena View Post
 hit the surface with the capsule going at around 22 m/s...rough landing...

That works out to 4,320 fpm. Almost certainly fatal. If not fatal then injuries are guaranteed as is extensive damage to the lander.
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