Challenge XR2 Ravenstar fastest docking with ISS

[dgatsoulis]

What's your best mission time (from "wheels up" to "contact") with the ISS?

Mandatory Parameters:
1)Use the XR2 "stock" scenario: "1 - Ready for takeoff to ISS"
(Full crew of 14 and the CHM loaded)

2)XR2RavenstarPrefs config file: MainFuelISP=2
SCRAMFuelISP=0


My best time was just under 13 min. (Mission Elapsed Time:12:55)

Can you do it faster?

EDIT: You will find a playback with the current record (9min 40secs), attached on post #5 of this thread

 

[n72.75]

Can you post a replay?

 

[dgatsoulis]

Can you post a replay?

EDIT: New record: 11min 57sec

The playback is attached in this post.

 

[dgatsoulis]

Broke the 10 minutes "barrier"!

I just gave it another try, with a slightly different ascent profile.

Result: NEW RECORD

9min 58sec from "wheels up" to "contact"!

 

[dgatsoulis]

"Pushing" it a bit more.

New personal best: 9min 40sec (playback attached)

Broke my own rules in this one, but only to make it harder.

MainFuelISP=1 (realistic) instead of 2 (default).

If you ever need to get to the ISS in a hurry... this is the ship to be on! :lol:

 

[Arrowstar]

"Pushing" it a bit more.

New personal best: 9min 40sec (playback attached)

Broke my own rules in this one, but only to make it harder.

MainFuelISP=1 (realistic) instead of 2 (default).

If you ever need to get to the ISS in a hurry... this is the ship to be on! :lol:

Dang, that was impressive. Pretty cool to see the ISS shoot over your shoulder like that, stop in front of you, and the in just the right orientation to dock. Very nice!

 

[ex-orbinaut]

Broke my own rules in this one, but only to make it harder.

MainFuelISP=1 (realistic) instead of 2 (default).

This is actually not as big a disadvantage as you like to think. The realistic ISP burns the fuel at about 20% higher rate, which gives you a reasonably good increase in power to weight ratio as fuel is burned and will certainly impove your performance in the initial acceleration phase.

Sorry, I have not looked at your playbacks yet, I take your word for it. My own time was 19:22, off one try (with default ISP). Might try again some time.

 

[dgatsoulis]

This is actually not as big a disadvantage as you like to think. The realistic ISP burns the fuel at about 20% higher rate, which gives you a reasonably good increase in power to weight ratio as fuel is burned and will certainly impove your performance in the initial acceleration phase.

You're right about that.
The only problem was that, with that ISP setting, there wasn't enough fuel to
make it to the ISS in less than 10 minutes (at least not in my first couple of tries).

But since it's -obviously- possible, and with fuel to spare, i guess there is still room for improvement.

 

[Bam45]

Idk how you lined every thing up so nicely to end up at the iss in less then 10 mins, I thought I was good doing it in a in an hour.

 

[dgatsoulis]

1st post? to the Forum!

BTW, you ARE good, if you can get to the ISS in an hour!

 

[Bam45]

ty
I mostly like sticking around earth going to the iss and back in a rx2 or rx5

 

[dgatsoulis]

Idk how you lined every thing up so nicely to end up at the iss in less then 10 mins

The "1 - Ready for takeoff to ISS" scenario that comes with the XR2Ravenstar has everything lined up pretty well. The rest was done with IMFD5.3 , DockingMFD and lots of practice.

I mostly like sticking around earth going to the iss and back in a rx2 or rx5

(Ab)using the XR series crafts is a fun hobby of mine too! :lol:


Have fun, happy orbiting.

 

[ex-orbinaut]

Ah, I had forgotten about this, but first...

Hi Bam45,

dgatsoulis;

IMFD? I used align planes and docking MFD's, + the flight computer illustrated below. Good enough to stop you pretty much on the dime next to ISS for the deceleration phase calculation, and the docking takes me about a two minutes from there. Tried it again a couple of times this morning and my times from scenario start up to dock were 19 mins (again) and 17 mins on the second. There's about a minute +30 secs to be discounted there for pre takeoff panel configuration and the take off roll. Default ISP.

Still have not looked at your playback (don't want to be influenced just yet), but a question.. are you using SCRAM and the main thruster's together?

I am doing things a bit by the book and shutting down the main engines before SCRAM light up, and arriving at ISS with 6% SCRAM fuel remaining and 2.5% main fuel.

Just that, then I will have a peek at what you're doing...:lol:

 

[dgatsoulis]

IMFD? I used align planes and docking MFD's, + the flight computer illustrated below. Good enough to stop you pretty much on the dime next to ISS for the deceleration phase calculation, and the docking takes me about a two minutes from there.

Hi Keith,

I have no idea what that is in the pic, but it looks way cool! Hey, is it our chess game on the right? :thumbup:

I push the throttle all the way up as soon as the scenario starts and also the scram. I then set up a target intercept plan on IMFD with time to intercept set to seconds. (I don't want to spoil it for you). I'm pretty fast with IMFD and all that is done by the time i reach "V1".

For the decelaration fase: again IMFD ->Orbital->Match Velocity

If you multiply your speed with the burn time and then divide it with 2, you get a very accurate distance at which to start the burn.

 

[Bam45]

Kinda looks like an E6B but I never thought about using it with orbiter lol.

 

[ex-orbinaut]

Kinda looks like an E6B but I never thought about using it with orbiter lol.

It´s an Arc-1, but essentially the same thing (a circular slide rule), and...

I have no idea what that is in the pic, but it looks way cool!

...it IS well cool! The series of pictures at the bottom show what I am doing. For an example I will use a closing velocity of 2,100 ms and a deceleration rate of 23 mss. At what distance do I start the burn?

Step_1: Turn the innner scale until 23 is under 21 on the outer scale.

Step_2: Without moving the inner scale, look for the number on the outer scale above the "10" index. 91.5 in this case. This is basically the time it will take to decelerate from 2,100 to 0 relative velocity, in seconds. Keep it in mind.

Step_3: Rotate the inner scale so that 20 is under your original speed (20 under 21). This is, as you well said already, dividing the initial speed by two.

Step_4: Without rotating the scale, look for the number on the outer scale above 91.5. It is more or less 96. That is the distance in kilometers at which you should start the burn.

Okay, there is a bit of holding the decimal places of each calculation in your head while you do all this, as it is NOT going to give you the exact answer without you having to "reason" it a little, regarding those decimal places (for example, think of the 21 in the first step as 21 hundred).

Let´s check that answer now.

((2,100 / 23) * (2,100 / 2)) / 1,000 = 95.86 km.

Not bad, except it is a LOT quicker on the Arc-1 (or E6B, as the case may be!) than on a calculator. Takes about 3 to 5 seconds, so you can do it on the fly with ease.

Topic change->

Now, in which folder did I leave that IMFD manual??? Have not tried the "Shuttle Express" again yet; been painting a gate, as it is my day off!

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

PS: (new PS)

Okay, it was the use of SCRAM and mains together that does it. IMFD not needed for this. On my fifth attempt at this (1st with Realistic ISP, mains/SCRAM combined):

Times:

Scenario start: 14:31:40
Stopped at ISS: 14:42:37
Docked: 14:44:41

Quite satisfied its not anything magical now, and not bothered about a minute or few seconds here or there. You go ahead and keep the record! Very nice, though. I am sure anyone would agree you get 100 points for originality of use of Orbiter!


All the best.

 

[XonE32]

Nifty stuff. I must look at these playbacks. 10 mins (less actually, is pretty cool).

I think my personal best was in hours not mins lol (course I've never thought to actually try and get there super fast). Something new to try.

Good job.

I do have one drawback though. I don't have ISS in orbit lol. I use StationV for most of my scenarios as i still have yet to master the docking with that station. I find syncing up and docking with that spinning beheamoth quite taxing.

EDIT:
bah i suck at this lol. using a diff .scn and taking off from Wideawake int'l but that shouldn't make a difference. still can't seem to get under 23min. Tips? (I'd love to know what yer doing with IMFD target intercept for this). My launch azimuth I calculated is fine but I'm still missing the target...like Kahn.

 

[dgatsoulis]

Tips? (I'd love to know what yer doing with IMFD target intercept for this)

Take off at the right time (when ISS is about 2M "behind" you) and follow "by-the-book" ascent profile with a correct heading. During your ascent, set up a target intercept plan on IMFD with ISS as your target and a ridiculously low Time to Intercept. (Not giving you an exact number, cause i don't want to spoil it for the people that want try it for themselves).
Follow the Burn vector of that plan on IMFD, (that's your heading!) but do NOT hit AB. Not until your "by the book" ascent gets to the point where you start running out of SCRAM fuel.
After the Autoburn you will be approaching ISS with a VERY high speed. Make sure you turn the ship around and null your relative speed at the right time.

That should help you get your time down to about 13-14 min.
Play around a bit with that profile and watch the playback again.

 

[XonE32]

Take off at the right time (when ISS is about 2M "behind" you) and follow "by-the-book" ascent profile with a correct heading. During your ascent, set up a target intercept plan on IMFD with ISS as your target and a ridiculously low Time to Intercept. (Not giving you an exact number, cause i don't want to spoil it for the people that want try it for themselves).
Follow the Burn vector of that plan on IMFD, (that's your heading!) but do NOT hit AB. Not until your "by the book" ascent gets to the point where you start running out of SCRAM fuel.
After the Autoburn you will be approaching ISS with a VERY high speed. Make sure you turn the ship around and null your relative speed at the right time.

That should help you get your time down to about 13-14 min.
Play around a bit with that profile and watch the playback again.

Thanks DG that hlps. I have a feeling that although I have the correct Launch Azimuth calculated; my "by the book" ascent profile must be from the wrong book. In other words I need to go back an reread the XR2 manual 'cause I'm doing it wrooong lol.

Thanks again!

XonE

 

[StevoPistolero]

I try to use LaunchMFD, but all it does is align the planes. It does not tell you what angle to be at or how to circularize your orbit. Any advice on how to do a non-IMFD rendezvous?