andre
Donator
- Joined
- Apr 3, 2011
- Messages
- 23
- Reaction score
- 0
- Points
- 0
Hi to all,
I´ve been playing with Earth reentry with the DGIV and the XR2 in the last few days, and I would like to share the experience with you all and perhaps get to some opinions about the differences between these spacecrafts. Any suggestions / comments on the reentry approach used are also welcome.
Let´s start with the DGIV.
DGIV:
I start docked with the ISS in the default circular orbit at about 350 km altitude. I then use the BaseSync MFD to search for the next encounter with the base and also look at the Map MFD to find a roughly good alignment with the runway. Well, I find a good approach for Cape, so I undock the ship with 2 orbits of anticipation of the meeting point and in the next normal/anti normal node I make a burn to get the alignment.
Then I throw some fuel off to get lower than 19 ton weight and wait until I get at the opposite side of Earth by looking at the Aerobrake MFD. I then make the retrograde burn and close the landing distance to the base, projected by the Aerobrake, to a minimum. Then I turn prograde and pitch up to an AoA at 40°, so the Aerobrake can project my trajectory more accurately. I then make some small corrections. I think ii helps to give some numbers, so typically all these will give me roughly an orbit with PeA of 50 km, a projection of distance from base when landing of 20 km, 0.8° reentry angle and the retrograde burn just west from Australia.
Well, everything ready for the show, so I check everything with D65 (retro and hover doors, weight, etc) and when about 100km I start the PRO104SPEC40 to keep my attitude with a initial AoA at 40°, turn the D3 to monitor the temperature and the Surface and Aerobrake MFDs. I like to look at the path projected by the Aerobrake before the reentry, and usually is some path going down from the 100km to 50km in more a less a straight line, then a small constant path at the 50 km and then the big dive to the ground, when the desacelaration really occurs and the heating will go up. Well, OK, let´s go!
At 95 km I try to choose a proper bank to align with the base and make some changes in the AoA in order to close the distance from base. When I´m at 60 km I finally lock a fixed target, which I choose 10 km short from base, so that will give me enough space to align with the runway and slow down. Then I keep going down like a flying brick until 50km, keep a little bit at 50 km and start following down and start to burn! At 45 km I get the temperature peak at 2050° and keep going down. At 30km my speed is more manageable at 1.000 m/s and finally I get visual contact with the runway. It´s really cool, because the ship is so fast that it always seems that it will pass the runway, but the speed drops to 800 m/s, so I turn off the autopilot, turn on the elevon & gear and turn off the RCS and dive aggressively (let´s not forget that we are really high at almost 30 km).
I´m always careful with the DGIV in the final approach, because you can get in trouble like stalling at very low speeds (this is a ship that doesn´t exactly behave like a good aircraft), so keeping this in mind I align to the runway but with some height margin. Deploy the gear with less than 250 m/s and manage to make a nice touchdown at 180 m/s. Cool!
XR2:
Well, the initial process is basically the same here, so let´s jump to the stage where I´m already aligned with base and made the deorbit burn. Looking at the Aerobrake path projection I usually get the first path from the 100 km to the 50 km a little bit more fast, and the constant path at 50 km little bigger and the final dive looks the same with the usual temperature peak. Well, everything ready, I check at D9 that we are ready for action (retro doors close, weight, etc), put the D3 to monitor the temperature, turn on the attitude autopilot in D2 for the usual 40° of AoA and start making some banks and changes in AoA in order to close the distance between the runway and the projected landing spot.
Here we have the first difference between XR2 and DGIV, probably because of the more aircraft behavior of the XR2 in the atmosphere, it´s not possible to lock the landing spot like the DGIV, I have to keep making fine adjustments all the way down. It´s not hard, but it´s necessary to pay attention during the process. I also target something like 10 km short of the runway and manage all my way down with the usual temperature peak at aprox 45 km, and turn off the autopilot also at about 800 m/s at 30 km.
The XR2 behaves perfectly at low speeds, so I don´t get much scared of getting in stall in the final approach, I deploy the landing gear and when very close to the runway I use the aerobrake and make a very very soft landing, with vertical speed to a minimum (sometimes I get less than 1 m/s) (the limit is aprox 3.6 m/s, very sensitive). Yeahh.. Really cool!
Final Considerations:
1) The DGIV goes all the way down like a brick, with the target landing spot practically locked in, while for the XR2 the target landing spot keeps fluctuating all the time.
2) At final approach the XR2 can almost be considered an aircraft with a very good flight response. Very different from the DGIV.
3) The XR2 has a fuzzy logic determining if your ship is destroyed when you pass the critical temperature, so you can actually survive some seconds over this limit, which make the experience more interesting. I´m not sure about DGIV, but I guess it´s a fixed number.
4) The DGIV has an amazing human simulation, with the heart beats, G´s limit for everyone in the crew which makes this part more realistic.
5)It´s not hard to distress your wings in the final dive or break your gears at final touchdown with the XR2. The DGIV looks stronger.
Well, reentry for me is one of the coolest things in orbiter and I am always playing with it. I find amazing the precision involved in the whole process, I keep imagining the ship docked with ISS going all the way down, with all the strong unregularly air friction and other perturbations that happens in very low orbit, and make all the way down and land like an aircraft in a runway! COOOOOL!
Hope you enjoyed the trip!
Best regards
Andre
PS: The screenshot attached was taken when in one approach I decided to go for the first runway (not the target one). Really really cool dive and landing!
I´ve been playing with Earth reentry with the DGIV and the XR2 in the last few days, and I would like to share the experience with you all and perhaps get to some opinions about the differences between these spacecrafts. Any suggestions / comments on the reentry approach used are also welcome.
Let´s start with the DGIV.
DGIV:
I start docked with the ISS in the default circular orbit at about 350 km altitude. I then use the BaseSync MFD to search for the next encounter with the base and also look at the Map MFD to find a roughly good alignment with the runway. Well, I find a good approach for Cape, so I undock the ship with 2 orbits of anticipation of the meeting point and in the next normal/anti normal node I make a burn to get the alignment.
Then I throw some fuel off to get lower than 19 ton weight and wait until I get at the opposite side of Earth by looking at the Aerobrake MFD. I then make the retrograde burn and close the landing distance to the base, projected by the Aerobrake, to a minimum. Then I turn prograde and pitch up to an AoA at 40°, so the Aerobrake can project my trajectory more accurately. I then make some small corrections. I think ii helps to give some numbers, so typically all these will give me roughly an orbit with PeA of 50 km, a projection of distance from base when landing of 20 km, 0.8° reentry angle and the retrograde burn just west from Australia.
Well, everything ready for the show, so I check everything with D65 (retro and hover doors, weight, etc) and when about 100km I start the PRO104SPEC40 to keep my attitude with a initial AoA at 40°, turn the D3 to monitor the temperature and the Surface and Aerobrake MFDs. I like to look at the path projected by the Aerobrake before the reentry, and usually is some path going down from the 100km to 50km in more a less a straight line, then a small constant path at the 50 km and then the big dive to the ground, when the desacelaration really occurs and the heating will go up. Well, OK, let´s go!
At 95 km I try to choose a proper bank to align with the base and make some changes in the AoA in order to close the distance from base. When I´m at 60 km I finally lock a fixed target, which I choose 10 km short from base, so that will give me enough space to align with the runway and slow down. Then I keep going down like a flying brick until 50km, keep a little bit at 50 km and start following down and start to burn! At 45 km I get the temperature peak at 2050° and keep going down. At 30km my speed is more manageable at 1.000 m/s and finally I get visual contact with the runway. It´s really cool, because the ship is so fast that it always seems that it will pass the runway, but the speed drops to 800 m/s, so I turn off the autopilot, turn on the elevon & gear and turn off the RCS and dive aggressively (let´s not forget that we are really high at almost 30 km).
I´m always careful with the DGIV in the final approach, because you can get in trouble like stalling at very low speeds (this is a ship that doesn´t exactly behave like a good aircraft), so keeping this in mind I align to the runway but with some height margin. Deploy the gear with less than 250 m/s and manage to make a nice touchdown at 180 m/s. Cool!
XR2:
Well, the initial process is basically the same here, so let´s jump to the stage where I´m already aligned with base and made the deorbit burn. Looking at the Aerobrake path projection I usually get the first path from the 100 km to the 50 km a little bit more fast, and the constant path at 50 km little bigger and the final dive looks the same with the usual temperature peak. Well, everything ready, I check at D9 that we are ready for action (retro doors close, weight, etc), put the D3 to monitor the temperature, turn on the attitude autopilot in D2 for the usual 40° of AoA and start making some banks and changes in AoA in order to close the distance between the runway and the projected landing spot.
Here we have the first difference between XR2 and DGIV, probably because of the more aircraft behavior of the XR2 in the atmosphere, it´s not possible to lock the landing spot like the DGIV, I have to keep making fine adjustments all the way down. It´s not hard, but it´s necessary to pay attention during the process. I also target something like 10 km short of the runway and manage all my way down with the usual temperature peak at aprox 45 km, and turn off the autopilot also at about 800 m/s at 30 km.
The XR2 behaves perfectly at low speeds, so I don´t get much scared of getting in stall in the final approach, I deploy the landing gear and when very close to the runway I use the aerobrake and make a very very soft landing, with vertical speed to a minimum (sometimes I get less than 1 m/s) (the limit is aprox 3.6 m/s, very sensitive). Yeahh.. Really cool!
Final Considerations:
1) The DGIV goes all the way down like a brick, with the target landing spot practically locked in, while for the XR2 the target landing spot keeps fluctuating all the time.
2) At final approach the XR2 can almost be considered an aircraft with a very good flight response. Very different from the DGIV.
3) The XR2 has a fuzzy logic determining if your ship is destroyed when you pass the critical temperature, so you can actually survive some seconds over this limit, which make the experience more interesting. I´m not sure about DGIV, but I guess it´s a fixed number.
4) The DGIV has an amazing human simulation, with the heart beats, G´s limit for everyone in the crew which makes this part more realistic.
5)It´s not hard to distress your wings in the final dive or break your gears at final touchdown with the XR2. The DGIV looks stronger.
Well, reentry for me is one of the coolest things in orbiter and I am always playing with it. I find amazing the precision involved in the whole process, I keep imagining the ship docked with ISS going all the way down, with all the strong unregularly air friction and other perturbations that happens in very low orbit, and make all the way down and land like an aircraft in a runway! COOOOOL!
Hope you enjoyed the trip!
Best regards
Andre
PS: The screenshot attached was taken when in one approach I decided to go for the first runway (not the target one). Really really cool dive and landing!
