XR1: first trip and thoughts

[Zruty]

Just a little flight report I want to share with you Together with some questions.

I downloaded XR1 and XR5 and wanted to have a test flight, and also to test AeroBrake MFD on my way back.

So, that's how my trip went.

1. Take off from KSC to the near-Moon-aligned LEO (couldn't quite align with Moon of course due to KSC latitude).
This was done OK, SCRAM engines were tested on the way up. The ascent profile differs much from a stock DG because of those powerful SCRAMs. Although a question: when can I close the SCRAM doors. Once I did this right after SCRAM engines cutoff and the craft exploded.

2. Transfer to the Moon. I did this using TransX to align plane and make a transfer in a single burn. May be not that fuel-efficient but much easier to do. Why does the coolant heats up in deep space with cut engines?

3. Landing at Brighton Beach. Descent hold autopilot is nice, so is auto-landing.BTW, I accidentally switched to AeroBrake MFD while Landing and it crashed. I think it's because id didn't have the dat file for XR1 and Moon has no atmosphere.

4. Returning back to Earth, aligning with KSC. LEO insertion and plane alignment were both performed with the atmosphere assistance, so I barely needed any fuel except for Moon escape.
AeroBrake MFD proved very helpful there.

I copied DeltaGlider.ld to DeltaGliderXR1.ld because I thought that the lift/drag coefficients are the same for both vessels, but I was apparently wrong. It seems that XR1 is slightly less aerodynamic (lesser lift/drag on AOA around 20-40 degrees). So I have a related question: Does anyone have the aerobrake data files for XR1 and XR5? And for DGIV as well? Autopilot calibration would be nice too.

5. Reentry and landing at KSC. AeroBrake MFD was of little help during reentry, because I had to constantly alter AOA and bank. Maybe I'm just not familiar enough with the tool? Anyway, Reentry MFD did its job superbly once again. I reentered without any flames, hull temperature has never reached 700 C. At the very end though I could have landed 100m short of the runway - I had to use my engines to avoid this.

BTW, is there a way to refuel/charge XR's APU in flight? Because all this aerobraking and reentry completely drained APU's power, so that I couldn't even open the airlock after landing. I though the crew was going to die in the end

Thanks for you time.

 

[Ghostrider]

1. at which altitude and speed did you close the SCRAM doors? The SCRAM jets are used in the 30000-60000m altitude range on level flight in order to gather up speed to later dash up and out of the atmosphere for the rest of the orbital insertion manoeuver without using up too much of the main fuel. When cruising on SCRAM from Mach 5+ to about Mach 15+ your main engines should be stopped.

2. the coolant heats up because it doesn't just cool your main engines, in cools the entire ship and its many systems. That's why you have to deploy the radiator once in orbit.

 

[dbeachy1]

Congratulations on your first XR1 flight!

Although a question: when can I close the SCRAM doors. Once I did this right after SCRAM engines cutoff and the craft exploded.

This is detailed on page 18 of the XR1 Flight Operations Manual. Use the Scram Doors switch on the upper panel, or press CTRL-G. For a complete list of XR1 shortcut keys, click and hold the Data HUD button on the main panel or refer to page 21 of the flight manual.

Why does the coolant heats up in deep space with cut engines?

As Ghostrider said, the coolant is to cool the electronics, not the engines. This is detailed on page 33 of the flight manual. Be sure to deploy your radiators once you reach orbit.

BTW, is there a way to refuel/charge XR's APU in flight? Because all this aerobraking and reentry completely drained APU's power, so that I couldn't even open the airlock after landing. I though the crew was going to die in the end

Refueling is detailed on page 31 of the flight manual. By default, you can only refuel APU fuel while landed on Earth, although you can change that by editing your Config\DeltaGliderXR1Prefs.cfg file. You can also change the APU's fuel burn rate and many other variables by editing your DeltaGliderXR1Prefs.cfg file.

Have fun!

 

[Woo482]

I did the same thing with the radiators just that I was in the xr5 flying in earths atmosphere and every thing over heated so my oxygen supply was turned of so I had to drop my altitude and open the cabin doors

 

[Zruty]

Thanks Doug for nice work on the spacecraft!
And on the manual too I've read it of course, but didn't memorize just everything. Sorry sir!

This is detailed on page 18 of the XR1 Flight Operations Manual. Use the Scram Doors switch on the upper panel, or press CTRL-G.

My question was a bit more complicated. I did the following:
1) Open SCRAM doors
2) Switched SCRAM engines on
3) After SCRAM fuel was about to deplete, switched SCRAM engines back off
4) (I don't remember, but maybe) switched the main engines on
5) Closed SCRAM doors.
After that, XR1 exploded.

Refueling is detailed on page 31 of the flight manual. By default, you can only refuel APU fuel while landed on Earth, although you can change that by editing your ConfigDeltaGliderXR1Prefs.cfg file.

I'm pretty sure I managed to refuel APU on the Moon.
Anyway, so there's no x-feeding fuel to APU in flight. OK

Thank you all for the answers, I've got only one question left:

Does anyone have the aerobrake data files for XR1 and XR5? And for DGIV as well? Autopilot calibration would be nice too.

 

[Zruty]

1. at which altitude and speed did you close the SCRAM doors?

I don't remember already. I guess the OS was about 5500m/s and Alt about 50-60 km. I cut off the engines because the SCRAM valve (don't quite remember what it was, don't have the XR1 now) was about to overheat (in the yellow zone).

 

[RangerPL]

The APU can be refuelled on the moon. The only fuel that can't be replenished on the moon is SCRAM.

This is more of a request, but it would be nice if there was an "APU autostart" so that it would start automatically if you want to open the SCRAM doors or something.

 

[thomasantony]

I don't remember already. I guess the OS was about 5500m/s and Alt about 50-60 km. I cut off the engines because the SCRAM valve (don't quite remember what it was, don't have the XR1 now) was about to overheat (in the yellow zone).

WEll the XR1 tends to explode when the SCRAM temps go into the red zone. It usually happens when you are nearly out of fuel. I usually do it when the TSFC bar goes high .. and I reach around Mach 15-17. by that time I am usually at around 70-80km or higher. The correct flight profile is given in the XR1 manual. Maybe 50-60km is too low for Mach 16.6 ( 5500 m/s)

~
Thomas

 

[pattersoncr]

My question was a bit more complicated. I did the following:
1) Open SCRAM doors
2) Switched SCRAM engines on
3) After SCRAM fuel was about to deplete, switched SCRAM engines back off
4) (I don't remember, but maybe) switched the main engines on
5) Closed SCRAM doors.
After that, XR1 exploded.

Get those SCRAM doors shut before you light-off the mains again. And watch you SCRAM diffuser temp gauge.

 

[SlyCoopersButt]

Indeed never light main engines before that scram door is shut. However, I have flown for about 45 mins to an hour above 60 km cruising at a roughly constant 6.3 something km per second on throttled down scram engines alone in the red zone without any issue in the XR5. It's extremely fuel efficent! Reached mach 20.8! Just make sure the guage doesn't turn white which means it could explode.

 

[dbeachy1]

Indeed never light main engines before that scram door is shut. However, I have flown for about 45 mins to an hour above 60 km cruising at a roughly constant 6.3 something km per second on throttled down scram engines alone in the red zone without any issue in the XR5. It's extremely fuel efficent! Reached mach 20.8! Just make sure the guage doesn't turn white which means it could explode.

That is good advice. If you are close to 8000 K and you light the main engines, the SCRAM diffusers will overheat and soon explode.

Note that since SCRAM engine performance decreases as you approach maximum diffuser temperature (8000 K), it is impossible to overheat the SCRAM engines using SCRAM engine thrust alone. So you don't need to worry about overheating the SCRAM engines as long as you don't fire the main engines or reenter from a higher velocity with the SCRAM doors open.