Getting to know the Ravenstar:)

[Grover]

best advice ever:

its just a simulation, it doesnt hurt to get it wrong, so dont panic, dont rush, and dont crash

 

[orbekler]

Using the standard scenario "1 - Ready for takeoff to the ISS", leaving default payload of 3384 kg (Crew Habitat Module) I scored 60.1% main fuel left at 212 x 202 km (or something like that).

I made a pair of (almost) tragic mistakes, :facepalm: so I guess there is room to gain some percentage points more.
Playback attached - Sorry, I forgot to delete useless vessels.

http://www.mediafire.com/?sb8nyirxbs2jb64

 

[dbeachy1]

Why isn't this in the manual? *Runs off to try it*

Good catch, I thought it was! :facepalm: I'll add a note about it to page 21 for the upcoming patch.

 

[Robsoie]

Using the standard scenario "1 - Ready for takeoff to the ISS", leaving default payload of 3384 kg (Crew Habitat Module) I scored 60.1% main fuel left at 212 x 202 km (or something like that).

I made a pair of (almost) tragic mistakes, :facepalm: so I guess there is room to gain some percentage points more.
Playback attached - Sorry, I forgot to delete useless vessels.

http://www.mediafire.com/?sb8nyirxbs2jb64

Congratulations on this attempt !

Very interesting replay, spotted a few things you did that will be very usefull to try improve my ascents.
Impressive to see that your XR-2 burning in extrenal view during most of the ascent

---------- Post added at 10:57 PM ---------- Previous post was at 10:28 PM ----------

After watching your replay, i think i understood where i could gain some fuel, because i was worrying about hull temperature with the scram, i was waiting until 20km altitude before lowering my pitch, doing it so i'm at 5 degree pitch when i'm 20km altitude (instead of being roughly at over 32 km) allowed my to spare a lot of fuel.
After that i'm always using the same method i listed previously in term of angles

Though i had to lower a bit the Scram power to keep the heat down at some point, but i could get back at full quickly enough, and heat never catched up again.

Thanks again for your instructive replay

Managed to get 61.4% main fuel left once i completed my roughly circular orbit.

Replay available there :
http://www.sendspace.com/file/48bny0

I'm sure with a few tweakings it should be possible to spare even more main fuel.

edit : oh, my orbit , while working, was not circular at all, it's 170x128, making my score invalid.
Should have checked the numbers, not the graphic display to be sure

Orbekler then continues to have the best score.

 

[Krikkit]

So, 61.3% on a 180 X 210km

and I made a video of it!

Considering how ugly this flight was I think I can get as high as ~ 65% if I get my accent profile perfected.

I recommend muting it, I accidentally left the mic on, so you can hear my TV in the background.

 

[Quintuss]

175x195 km 69.8% main fuel. Next time ill take less SCRAM fuel.

 

[agentgonzo]

Good catch, I thought it was! :facepalm: I'll add a note about it to page 21 for the upcoming patch.

I think for the past few years you have been the only person who knew about this functionality. The rest of us mortals have been panicking as soon as the autopilotlady starts screaming about impending doom.

---------- Post added at 09:32 ---------- Previous post was at 09:30 ----------

Try to keep hull temperature and dynamic pressure low. If those rise too much, you are wasting fuel (that is converted into heat).

Not necessarily true. You will have more drag and wasted energy, but at the same time you will find that higher dynamic pressure can increase your SCRAM thrust (and thus fuel efficiency). Doing some crazily-unsafe high-powered ascents I've had the SCRAMS putting out over 1.1MN of thrust and the hull temperature in in the red-zone (and bordering on the white-zone). This more than compensates for the increased drag at higher dynamic pressures.

 

[Sky Captain]

I have had few scram engine explosions when using main and scram engines together and not managing to close scram doors on time. Otherwise it is not possible to blow scram engines unless you start mains and leave the scram door open.

 

[TMac3000]

Thanks for the replies everyone. Looks like my ascents need a loooot of work The best I can do is about 33% main and 70-something percent scram fuel remaining:facepalm:for about a 230 km orbit. I only run my scrams between roughly 14 and 90 km at 15 degrees pitch.

Changing my ascent procedure will also mean practicing direct ascents to ISS all over again. Fortunately, those are fun

 

[Robsoie]

Yes, it's great fun to see how much you can optimise your ascents when tweaking your own methods, additionally you learn a little bit more each time too and can get interesting procedures from other Orbiter pilots

 

[orbekler]

175x195 km 69.8% main fuel. Next time ill take less SCRAM fuel.

Even if Orbiter is "just" :lol: a simulator, is a disciplined one, and for challenges it reqires at least at rule of thumb:

1) the same initial condition;
2) a target within a certain tolerance, the bigger is (the tolerance), the more doubtful is the result, as uncertainty grows;
3) a playback (or CLEAR clip) of the challenge.

I'm just saying that 69.8% seems a bit too much optimistic, not speaking of the orbit, a bit far away from the circular 200km target.

Because we're speaking of fractions of percentage of fuel, every km counts.

You'd better provide also a playback, that could be useful to the community to learn from such outstanding figures.

 

[Quintuss]

A day after tomorrow ill have 3 days off work and ill post a replay. Wideawake XR2 to ISS scenario without cargo or crew. My previous post was about of "out of the blue" attempt. Ill try better this time My best attempt as i remember was of 73% fuel at stable orbit. As stable i mean 150 km +.

 

[orbekler]

A day after tomorrow ill have 3 days off work and ill post a replay. Wideawake XR2 to ISS scenario without cargo or crew. My previous post was about of "out of the blue" attempt. Ill try better this time My best attempt as i remember was of 73% fuel at stable orbit. As stable i mean 150 km +.

That's a different challenge.

 

[Robsoie]

Yes, the challenge is :

-start from default settings for XR-2 (start from "Ready for take off to ISS" default Ravenstar mission is the best conditions for this)

-Ascent and get a circular orbit (at least roughly circular) while having in the end as much Main engine fuel remaining as possible, it is not important if you have Scram fuel left or not, the challenge is about main fuel.

-Considering a Low Earth Orbit is at minimum 160x160 km to avoid some decay due to Earth gravity pull, so you need to get there or above, not under this.
Another target can be 200x200 km orbit if you want a variant for the challenge

-Provide a replay to validate your record, and help people learning too.



---------- Post added at 11:21 PM ---------- Previous post was at 10:35 PM ----------

Managed to get 62.1 % main fuel left with some adjusting in my previous ascent method, ending with a 167x161 km orbit



Replay available there :
http://www.sendspace.com/file/lytoo8

Will try the 200x200 soon to see if i can improve

 

[orbekler]

Ok then, 160 x 160 km, same scenario, it must be just the same target for all.

 

[C3PO]

-Considering a Low Earth Orbit is at minimum 160x160 km to avoid some decay due to Earth gravity pull...

Just to avoid confusion among rookie Orbiteers.

Orbital decay stems from atmospheric drag, not gravitational force.:facts:

As you were.

 

[Robsoie]

Learn something new everyday is always good, i was so persuaded it was gravity pull that i didn't double checked

Anyways back to fuel sparring attempts, i tried the 200x200 orbit challenge and managed 61.2 % at an orbit of 206x202 km


Replay is there :
http://www.sendspace.com/file/es0xl2

I had took a longer time than usual to build my orbit from the apogee node, as i was worried of being too much into the Ap node on the orbit MFD, as in a previous 200x200 attempt i was a bit too much into it and in the end before finalizing my orbit i was ahead of that node, leading into too much corrections to do to recircularize at 200.

 

[railfanatic844]

for launch, i get up to about 100 throtle, then get up to 100 knots, then launch at 15 degrees, airspeed hold, then finally wait till i get to 24km rotate down to 10 degrees, then engage the scram jets. I then burn the scram jets, still burning at about 10 degrees. After that, what i do is that i go to 60km then turn off the scrams, put on the main at full, til the APA is at 200k then i cut off, then circulize the orbit in a later burn. always works. re-entry, i have no idea (likewise the shuttle)

-AJ

 

[orbekler]

Just to avoid confusion among rookie Orbiteers.

Orbital decay stems from atmospheric drag, not gravitational force.:facts:

As you were.

Of course, not even 300km are safe from drag, but for this kind of challenge is non influential.

 

[TMac3000]

I am pleased to announce that my results have drastically improved: I figured out a proper SCRAM ascent, and my new record is about 58% main/<10% SCRAM.

My new profile follows:

Initial ascent to 15 km at 60* pitch

Acceleration to Mach 3 during the pitchdown

SCRAM ascent starts at level flight, then I pitch up to 10* when the hull temp starts making me nervous:shifty: Usually peaks around 1300*C

When SCRAM thrust is below about 50 kN, I kill SCRAMs, close the doors, push the mains to full, and pitch up to 30*.

I then use IMFD Orbital screen to circ my orbit. Target orbit: 230 km circular.