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Author Topic: Spint Development Thread  (Read 21665 times)
smoothvirus
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« on: March 31, 2006, 12:22:52 AM »

For development of the Sprint CEV proposed by Terry Wilson
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Zachstar
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« Reply #1 on: March 31, 2006, 12:33:35 AM »

Ok obviously the crew needs to get the the Hab in orbit to begin their trek to mars.

Now it has been accepted that a Falcon 9 will haul this craft. Hence the name Falcon Sprint.

Now thats 8,700 kg of mass to play with so here are some ideas.

2 main objectives per mission

Lets say MC deorbits the craft as soon as the crew departs. What a waste if it did! We have a capsule up there thats fully able to return why not give it a few weeks to have a secondary objective?

Like sciences that can run without human intervention. (Fish, Bugs, stuff like that) Or earth observation or flybys of other sats in its plane.

Batteries instead of solar panels.

How about this idea? I mean if you put good quality batteries in there, Do you really need to waste money on expensive solar panels? I mean look how long the average nonrechargeable battery lasts these days. Can the bunny power the craft through primary and secondary objectives?

Just some ideas to fire up the debate.
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Zachstar
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« Reply #2 on: March 31, 2006, 01:05:56 AM »

Moved from live modeling topic





By Aftercolumbia
I'll see what I can do. One thing I've been thinking recently is that the saddle bag arrangement of the life support system in the Descent Module, while great for access, might be a pain from the perspective of the cabin's pressure integrity (which has the ultimate effect of making it heavier and more expensive.) I'm thinking that the pressure cabin would have a conical/cylindrical set up. The forward section would be conical, while the aft section would be cylindrical. Up near the front the cabin gets pretty close to the OML, which means that the forward RCS quads would grow out in blisters. The aft part would have the stuff in a toroidal arrangement. I'd like to have the most hazardous stuff outside the cabin and the most maintenance intensive stuff inside, and when a component has both ( i.e. batteries and oxygen candles) to have them inside the cabin, as if systems this critical fail, you die anyway, just more slowly if they are outside the cabin. As far as endangering a mission package or space station, slam the hatch and hope your not screwed. Having them outside the cabin eliminates only the "slam the hatch" step. The O2 and N2 containers are low maintenance, and even if they do fail, there is little that can be done to prevent it short of full replacement.

So...the toroidal aft section around the cabin's cylindrical portion. In the cabin itself are the two pilots (passengers get the forward two seats), between them is the control caddy, above them is the life support and propulsion system management panels, and in front of them are the fold down LCD workstations (on pretty meaty arms that keep them from falling onto their chests during a 20g abort entry.) Around the cabin, above them is the main parasail, below them (left and right) are the landing bags. The landing bag pressurization system is between the strips. There might be enough room for a doodad in there too. Left and right (behind the hatches) are the propellant tanks. Probably will have a total of four tanks: two little GN2 pressurant tanks, two bigger N2H4 tanks. Then the life support supplies: two more little GN2 tanks (primarily there for emergency repressurization...this is for the case if you're on a station or mission and you have a cabin leak in the mission, rush to the capsule and slam the hatch shut just before passing out, Sprint can repressurize the cabin for you so you can come to and figure out what's going on. A good idea is to have a bit of N2 and 02 let into the cabin when it is below station pressure...not a whole lot so you don't run out...this way there is positive pressure on the interior hatch when you close it, and it may be possible to repressurize the cabin without it being latched all the way.) This makes for a total of 8 tanks: four on each side...2 GN2 propulsion (small), 2 GN2 life support (also small), 2 O2 life support (big), and 2 thin walled N2H4 propellant tanks (biggest, but not by much.)

The batteries are in the cabin, behind the pilots' seats in hot-reconfigurable racks which are moved around to affect entry alpha trim. The cabin lights are LED based to save power, and because LED's are comparatively invincible compared to most lightbulbs and can survive rediculous stuff like decompression and 20g aborts.

bheick



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PostPosted: Wed Mar 29, 2006 4:09 am    Post subject:    Reply with quote
Hello, I am interested in modeling the Delta Sprint CM. I have plenty of time on my hands so I can lend you guys a hand.

Now if you guys would like I can get started on this right away, but there is some data that I would require in order to make the model as accurate as possible.

Starting off:
Model Details
-Measurements in key locations
-Diameters of specific/non-specific areas
-Poly Budget

Draw-ups
-Technical drawings, drafts, scanned pen or pencil sketches. Anything works for me.

Textures:
-Size, 64x 128x 512x 1024x
-Color Scheme

As soon as that is all worked out and a basic model is finished, then fine details such as feature details like in the cabin, hatch locations, and any other features for the model.

I already started a basic model that can be worked on as progress goes on. This is from data collected from post seen here and some other images. I know its wrong, but it gives a general idea.

Iceversaka



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PostPosted: Wed Mar 29, 2006 4:24 am    Post subject: Answers    Reply with quote
I'll start with the obvious:

Texture size Standard 256x256, high res 512x512 should be fine.

Measurements in key locations.
Base is 4 meter diameter

the neck of the nose cone around the doors...lets say 2 meter diameter....so half the radius of the entire capsule.
Looks like the doors drop down about .75 m - 1m from the very tip.
*just eye-balling here*

Poly budget maybe 5k at the very max, shoot for 2k-3k.

Color Scheme...lets go with the standard light grey/white and black nasa colors with flags and we'll get you something to paste on the side later.

Probably start by blowing the sides out to fit the radial profile, and fix the radius on the nose hatch....Terry can reply and give additional suggestions and help to guide the modeling as well. He will have a better idea of the technical internals and systems integration, ect...

Seth

bheick



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PostPosted: Wed Mar 29, 2006 2:06 pm    Post subject:    Reply with quote
Okie, now there’s some data

I did some work on the model this morning using the information supplied.

And here is render to boot.
http://kimages.be/share/84690359.jpg

I followed one of the images posted in another thread as a tracing reference.

The Vessels total size is 4.85m x 4.0m

The Main Hull Diameter is 4m at the base and 2.17m at the top, and 4.19m in length.

The Nose cone doors are 2.17m in diameter and 0.85m in length. It can swing a full 180* without penetrating the mesh on a fixed pivot. Inside there is plenty of room to play around.

bheick



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PostPosted: Thu Mar 30, 2006 3:11 am    Post subject:    Reply with quote
Little bit more work done

Finished the Crew Entry Hatch, Cut it in real smooth, 24 sided.

Now onto the fine details

http://kimages.be/share/53624486.jpg

BTW: I need a paint scheme for this model.
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Iceversaka



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PostPosted: Fri Mar 31, 2006 1:41 am    Post subject: bheick's latest    Reply with quote
bheick posted this to me earlier:

http://kimages.be/share/33339945.jpg

Seth
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aftercolumbia



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PostPosted: Fri Mar 31, 2006 2:03 am    Post subject: Lovin' it!    Reply with quote
Sorry, I'm late...I managed to miss the messages sent to me about this thread's existence.

I think that's great, I overestimated the length of it obviously, I think my originals may have included the Service Module. My best crack at getting specification drawings is on Sunday (2 April), so I'll try to rough in the earth parachute and airbag hatches. It goes without saying the mission package (which for the Mark 1 will be the main landing parachutes for the initial ERV landing on Mars) isn't in yet. We probably won't need the nose doors. Great job on them by the way, the lines on the inside look almost exactly like the sort of fairing internal acoustic/thermal blanketing already (needed to keep from frying the radar), of course they'd only be on the inside.

Those lines also bear an almost passable resemblence to LRSI tiles. The actually chosen AFRSI for most of the craft is easier to do, and the white on the main body right now is pretty close even without texturing (specular reflection is a bit high, the AFRSI tends to do more of a matte reflection.) For reference, find any Shuttle or Mir book and look for pictures of the Atlantis that they took...Actually, I'll go find one right now.

http://spaceflight.nasa.gov/gallery/images/shuttle/sts-114/html/iss011e11014.html

This one has lots of good references actually. The RCC in the nose is the ferry versions heatshield, I don't have a picture reference for the microballoon ablative, but RCC is pretty passable for appearances...merely looks too boring, but utility says no paint is going to survive on RCC or ablative anyway.

AFRSI covers most of the nose, I hope you find it easy to sort it out from the "white tile" LRSI, most of which is behind the windshields. Finally, there is the docking port in the payload bay, the same type as planned for the Sprint's. The Sprint docking radar, which will be in one of the nose doors, resembles the Ku-band dish near the bottom of this image, but it isn't that big. 10 inches will do. If we have ground tracking support for rendezvous it won't need to be any bigger (the MFDs in Orbiter have omniscient suck-it-out-of-the-memory support, which is accurate to a dozen decimal places.) If you really have trouble sorting LRSI and AFRSI, find a picture of Columbia and look for what it doesn't have: Columbia never had a stitch of AFRSI.

The docking port is only applicable to Sprint's Ferry, ERV Mark 2, ERV MM-on-top (ERV versions don't need nose doors, to support both with few mods, it may be helpful to put the radar dish on its own arm, rather than mounting it to the door.) Sprint ERV Mk. 1 does not need a docking port.

By the way, the side hatch seems a bit small. I specified an elliptical hatch, but as I think about it, a one-metre round hatch is fine. It can't be any smaller because then it gets tough to jump out of in a pressure suit with a parachute on your back, and it shouldn't be any larger becase that would make the craft heavier, as the loads need to go around the hatch under most circumstances. The hatch will also be flush with the outer mold line.

Great work, and thanks for the help!

Zachstar



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PostPosted: Fri Mar 31, 2006 2:49 am    Post subject:    Reply with quote Edit/Delete this post
Well even if the top bay does not house a docking port it could hold a large parachute for aborts and in case the main ERV's parachutes fail. Who knows.
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Zachstar
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« Reply #3 on: March 31, 2006, 01:09:14 AM »

Sorry about this move yall but it was important that we keep development in these topics active to make the most of our limited time.

Continue ALL SPRINT debate and production here!

Thanks again later.
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aftercolumbia
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« Reply #4 on: March 31, 2006, 12:15:29 PM »

Zachstar's jumping the gun a bit on the name (probably because I agreed on the launch vehicle over email); the name of the spacecraft is Sprint without any reference to the launch vehicle actually in the name.  The original name of Delta Sprint was due to the original Sprint Program's early selection of a launch vehicle (the Delta II 7920H) and the desire to develop a spacecraft around it.  The Sprint Program was After Columbia's first project to answer the question, "what if the investigation board recommends that the Shuttle never fly again?" starting on 2 February 2003, about 28 hours after STS-107 broke up over Texas.

The situation has changed a bit since then.  One thing is that research has discovered the design loading condition is not ascent, but an uncommanded abort at about 5500m/s during ascent, which leads to a 20g loading entry about 3000km downrange of the launch site (depending on certain launch vehicle factors.)  Such an entry has occurred in piloted spaceflight.  Known as Soyuz 18A, a Soyuz flight which does not have an official number.  In 1974, a Soyuz stage 2/3 separation failed...at about 5500m/s ground speed.  The unfortunate Salyut 6 crew wasn't particularly concerned about the spacecraft surviving their 17g entry, they kept asking "Are we going to land in China?"..."No"..."Are we going to land in China?"..."No"..."Are we..."  They landed about 200 miles north of China on a mountainside...which they started rolling down.  Luckily, the parachutes snagged on a tree and the descent module halted 6 feet away from a cliff with a 200 foot drop.

Anyway, a craft that can survive all that really doesn't care too much what launch vehicle it winds up on, as long as the performance is adequate.  Keeping burnout accelleration under 4g for the comfort of the crew would be nice, but being as SpaceX brags about having the mildest launch environments (without providing any numbers yet), this shouldn't be a problem.  Another consideration is the Service Module, which has to carry the Descent Module into space, but is not retained for entry.

Sprint winds up flaring a bit on the Falcon 9, but not anywhere near as much as the 5.2m fairing.  It is also shorter than the 3.6m fairing, even with its Service Module.  It will need partial fairing protection for the Service Module.  With loads transferred through the Service Module rather than the fairing, this fairing comes off during ascent, unlike the fairing for Apollo's Lunar Module  It has always been the intention that the Paylaod Escape System be used during the upper stage staging event of a normal ascent to mitigate its impact on the payload mass, and to protect the service module from the exhaust plumes, the partial fairing is not staged until after the PES has been fired.  The sequence goes like this, regardless of the launch vehicle that Sprint is on:

- Booster 1st stage cutoff
- Booster Stage 1/2 separation
- Sprint PES motor fire (pulls Sprint DM, SM, partial fairing and Booster 2nd stage)
- Sprint arm BMM for emergency separation function
- Booster 2nd stage startup
- Sprint jettison PES motors
- Sprint jettison SM fairing

(For Soyuz 11A511U and Greenstar, this happens at the Stage 2/3 separation sequence.  1/2 sequence stagings applicable to Delta II, Delta IV, Falcon 5, Falcon 9, Atlas IIAS, Atlas III, Atlas V, and Sea Launch.  Soyuz 11A511U, Delta II, Falcon 5, and Atlas IIAS have performance only sufficient for the original Delta Sprint, not the four person Sprint we are currently working on.)
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aftercolumbia
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« Reply #5 on: March 31, 2006, 01:24:39 PM »

http://www.spaceref.com/news/viewnews.html?id=1095

"At the forward end of the Dragon is a hinged nosecone that opens to reveal a standard ISS CBM (Common Berthing Mechanism) fixture, which will allow docking with the U.S. segment of the ISS. It is wide enough to allow standard ISPR racks to be carried between Dragon and the ISS - just as U.S. modules currently on-orbit allow. Dragon is grasped by the station's robotic arm and moved into place and docked."

So...as at home as the bullet shaped Sprint will look on Falcon 9...there a Falcon Sprint already...they were going to call it Puff the Magic Dragon I think, but that name's taken (by a C-47 with a bunch of guns sticking out the side, IIRC)...It has gone through a sister process of name reduction down to simply "Dragon".

Up to 7 people, and flush with the booster's 3.6m diameter...looking at the pictures, it does appear that Sprint is ahead (at least in my head) and with no numbers (Sprint has numbers) I have no idea whether this 5 years Elon's been monkeying around with Dragon amounts to as much as the three I've been monkeying around with Sprint.  It is also plainly obvious that Sprint is equipped with a helluvalot more in the line of abort propulsion, but unlike Dragon, sheds the biggest chunk of it during ascent. What's left of it appears to be equivalent to what Dragon has:

"Dragon is also designed with safety and reliability in mind. Below the capsule (crew compartment) is an integrated service module. In addition to on-orbit operations, the service module can also provide the combined crew compartment/service module with the ability to pull the entire crew and cargo off the pad or out of the flight path should an abort be required."

It appears to land with its Service Module, but I can't figure out how it lands; I can't see any powered landiing propulsion assets, parachutes, or landing gear of any description.  Contrary to what their information policy appears to be on their website, they've been pretty secretive about this thing...I think there's enough room in that Service Module to hide enough landing assets...and if the above "pull the entire crew and cargo..." abort assets are usable for a powered normal landing, it may be that, with an emergency parachute bump/splash capacity used only for aborts.

I don't like powered vertical landings, though...you are dead if something goes wrong (I don't count helicopters...the reason is because the rotor acts as a type of wing during unpowered flight, and it is possible to land a helicopter without power through autorotation, the intended landing mode of Roton, may she rest in peace.)

It seems that the Corona shape is very, very popular, what with CXV, Dragon, other CEV concepts, DC-X, and Roton using it.  Sprint looks wierd among her sisters, eh?
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Zachstar
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« Reply #6 on: March 31, 2006, 05:06:18 PM »

Good job yall!

Ok just making things clear lets keep the discussions in this topic to the Sprint that will be on the current ERV design.

When production on Ferry Sprint starts then we will change the topic to that Tongue

Keep up the good work yall!
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aftercolumbia
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« Reply #7 on: March 31, 2006, 06:14:16 PM »

Haha, I just noticed the new name in the topic title "Spint"... :lol:

This is just to let everyone know that I've started a pair of topics; Sprint ERV and Sprint Crew Ferry, as they do have differing requirements.  I'm not sure if bheick is going to do both or OrbiterFan will get involved on Crew Ferry at this point (seems unlikely though.)  The ERV devel seems to be aligned on Mark 1.  I'd like to continue this thread on discussing the ERV Mark 1, as this thread is for discussing ERV issues in general, rather than exclusively Sprint issues.  The Sprint ERV thread is primarily for Sprint issues, mostly as it pertains to handling aborts in the Marks 2 and 4 ERVs (the "abortable" ones.)

I have a tendency to direct link into topics, so I might miss something like this.
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« Reply #8 on: March 31, 2006, 09:07:45 PM »

Quote from: aftercolumbia
Haha, I just noticed the new name in the topic title "Spint"... :lol:

This is just to let everyone know that I've started a pair of topics; Sprint ERV and Sprint Crew Ferry, as they do have differing requirements.  I'm not sure if bheick is going to do both or OrbiterFan will get involved on Crew Ferry at this point (seems unlikely though.)  The ERV devel seems to be aligned on Mark 1.  I'd like to continue this thread on discussing the ERV Mark 1, as this thread is for discussing ERV issues in general, rather than exclusively Sprint issues.  The Sprint ERV thread is primarily for Sprint issues, mostly as it pertains to handling aborts in the Marks 2 and 4 ERVs (the "abortable" ones.)

I have a tendency to direct link into topics, so I might miss something like this.

I'll work on whatever I get assigned. Think of me as someone who just dose what they are told.

Anyway, I have the Sprint CM on my work agenda right now, and with Seth giving me some guidance on shape and visual cues progress is moving quite smoothly.

Seth brought up a question about the CM/SM RCS placements. Are these going to be inset into the hull for aerodynamic stability, or a placement of a few RCS quads?

In order to add the RCS in I need to know that and their locations. If they’re inset, then that would make modeling the RCS very easy. If not, then I need the locations specified and the firing angles.


Some Dev Shots:
http://kimages.be/share/17849121.jpg
http://kimages.be/share/25083307.jpg
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« Reply #9 on: March 31, 2006, 09:25:03 PM »

slight change in the windows
http://kimages.be/share/76900012.jpg

these shouldn't conflict with the parasail location which is just behind the top windows
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Zachstar
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« Reply #10 on: March 31, 2006, 09:33:46 PM »

Holy moly!

That model is coming out to be very nice man!

Keep up the great work!
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« Reply #11 on: April 02, 2006, 02:31:19 PM »

OK, the exterior mesh model is done and sized up for the internal components. I have generated a set of 512*512 and 1024*1024 texture maps for this model. I'd suggest going with 1024*1024 just for detail.


Here’s the finished external Mesh with the 1024 blank texture map applied.
http://kimages.be/share/56190259.jpg

I do need some information on items such as external components, and placements still, and hopefully after all that is added in the CM exterior will be done.
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« Reply #12 on: April 03, 2006, 03:46:45 PM »

A quick model update

RCS thrusters for the CM

There are a total of maneuvering 12 thrusters.

http://kimages.be/share/15367523.jpg

Starting from the inside, translation (forward,backwards) / rotation (roll) translation (up, down), yaw / translation (left, right)

http://kimages.be/share/9184800.jpg
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aftercolumbia
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« Reply #13 on: April 07, 2006, 03:05:34 PM »

I can't quite get it in my head which way the thrusters are pointed in your renderings...please help me with that (i.e. plumes, or transparent modules, or even just doodles on the current renderings.)  We should put them in modules, the idea being that we can pop them out and inspect them because Crew Ferry is intended to be reusable (and with maintenance via EVA), and Sprint Mars might need the dust cleaned out of them, or other such maintenance as might be required after sitting on Mars for almost four years.  It doesn't have to be implemented in Orbiter as anything removable, it just has to look like it.

The windows...aw...the windows.  I search through my brain to find away to put this politely and my brain fails me so I'll be blunt...they suck.  Don't take it personally though, my drawings suck worse and I haven't put a whole lot of thought into what to do about them anyway...but hopefully that situation will improve this weekend.

The requirements I had in mind for windows were based entirely around the original 3 person Delta Sprint operating in the following modes:

1. Abort configured liftless entry; aerodynamic stability ensures proper pitch/yaw entry attitude is acquired, the roll angle doesn't matter; no windows required.
2. Lift configured entry; end of normal mission with operational electrical and data systems, automatic entry guidance backed up by pilots standing by; accurate visual roll reference required for the aft crew seats (cameras okay).
3. Lift configured entry; end of normal mission with operational electrical and data systems, but malfunctioning or dead guidance.  The pilots are manually controlling entry by following a cue-card roll angle schedule.  Accurate visual roll reference required for aft crew seats (cameras okay).
4. Lift configured entry; end of normal mission with dead electrical and/or data systems.  Pilots controlling craft via manual thruster valve switches operating on emergency power.  Visual roll reference independent of electrical and data systems needed (windows or periscopes.)  Roll angle maintained at zero degrees, therefore descent module will execute a skipping entry that will take it downrange of the normal landing site.  For this case, degredation of entry corridor and directional accuracy is allowed.  Visual roll reference accuracy can therefore be relaxed.
5. Normal landing under parasol; operational electrical, data, guidance, and brake command 3 axis visual reference required for pilots, VOR/ILS, GPS, TACAN radio references may or may not be available.  Forward visibility is needed, a contact line or laser altimeter can be used to time the final flare.
6. Dead parasol; can be caused by electrical, data, brake command, deployment failure, or loss of visual reference needed for controlled parasol landing.  Disconnect parasol and deploy round reserve chute.  Brace for impact...it'll be a rough landing.  The reserve parachute DM attitude is the same as it is for the parasol, perhaps with the nose up a bit higher is okay.  The reserve parachute is either in its own bay forward of the main parasol bay, or is in the same bay as the main parasol, forward of it.  Bheick can decide, but it doesn't have to be modelled for this version anyway.

Lifting entry cases lead to a requirement to have the region from entry interface to peak loads be in daylight for the end of a normal mission, or the pilots won't be able to see the horizon.  This would restrict entries to where the landing zone local time is from somewhat after sunrise to just after sunset.  In a just after sunset case, Case 4 would lead to the pilots losing the horizon after the normal peak loads point.  Hopefully by then the craft will be going slowly enough that roll angle doesn't matter any more (Case 4 is a very desperate and unlikely condition.)  It is likely that the requirement for visual roll reference for entry could be waived after the vehicle's reliability in the normal modes has been proven.  The reason is that putting time-of-day restrictions on entry and landing wreaks havoc on the scheduling for space station crew transfers, and might not be compatible with a Mars Direct ascent rendezvous.

Most visual reference was going to be provided by RocketCams (and at about $150,000 each, might even be cheaper than cutting windows into a 20g entry capable spacecraft!)  Of course, the RocketCams need windows, but these are puny enough to be ignored.  They would be positioned probably near the thruster pods, so the cable and plumbing runs are together, and also so that the plumes can be seen to confirm thruster operation.

The cameras I had planned out were a landing cam, which was put in the front of an airbag compartment and protected by it.  It points down and forward, so you can see where you're going under the parasol.  Another possibility for the landing cam was to put it in the lower thruster pod so that it always worked, and could also be used to assist docking.

The second camera was a centreline docking hatch camera to help with rendezvous and docking.

The third was a nose door mounted camera that looked across the docking port so it could see the docking ring and help guide the last few inches of a docking approach, keeping an eye on such things as alignment and angle, and providing more information on relative positions and motions after docking, but before retracting the dampening rings.

The fourth and fifth were side pointing cameras in the aft thruster pods to provide the emergency roll reference needed.  They are fixed, with really wide angle lenses.  The interface computers put a Sprint referenced HUD over the processed image so that the pilots can quickly find the angle between the horizon and the spacecraft's Y axis (i.e. the roll angle.)  Once rolled over far enough, one will see the sky, while the other will be "in the dirt."  Entry plasma effects (that orange glow) will keep the cameras from seeing the stars and the effect of the horizon blotting them out if entry is at night.  It would also defeat thermograph cameras, which would have otherwise have no problem seeing the horizon at night.

What about real windows?  Only two were needed, the left and right for each pilot, to let them see the horizon should the electrical system or camera data network screw the pooch on the way down.  On Delta Sprint, the pressure envelope went out to the outer mold line and the hatches were next to the pilot seats, so I put the windows in the hatches.  Now, the hatches are further forward and there is a big gap between the pressure cabin next to the pilots and the outer mold line, making "normal" windows impossible.

There are two solutions:

1: A passive periscope, like those used on armoured vehicles.  The outer cover glass would still look like a window, and when I visited airshows with armored vehicles as an Air Cadet, it actually was hard to tell it was a periscope and not an actual window.  This window would have a small appearance on the outer mold line.

2: A recessed window, like they had on the Apollo LM.  This puts a fairly small window in the cabin envelope with a big conical depression around it to the outer mold line so that angular visibility doesn't go down the drain.  The problem with this arrangement is that it would act as a plasma trap during entry, causing localized heating right in front of the window.  Therefore a layer of high grade thermal glass needs to cover the opening at the outer mold line; this glass need not be pressure bearing.  The window in the cabin would be about 200mm wide, while the window in the outer mold line would be about 600mm wide.  In this case, the windows would need to be positioned next to the pilots's heads, so a bit above the "waterline" with the DM horizontal.  The hatches could have little windows too, but being as we don't really "need" to see anything out of them (unlike the pilot's windows), they can be small or absent.

The part I really did not expect were _square_ windows.  The corners of square windows in pressure cabins encourage the formation of fatigue and stress cracks, which is why Yoke Peter and three other de Havilland Comet airliners exploded in 1952.  Nowadays, even the big viewscreen type pilot windows have rounded corners.  The canted posts also discourage crack formation.  SpaceShipOne experimented with oval viewscreen type windows.  I think the windows _really_ need to be round because the craft bears a 14.7psi pressure differential, while the typical airliner bears only 8psi.

Great work bheick, thanks for your help.
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aftercolumbia
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« Reply #14 on: April 07, 2006, 03:13:33 PM »

Hmm...I was just looking back through.  Does it have the hatch on the left side?  I can't quite see it.  Unlike a gliding vehicle, if the poor thing has both main parachutes screw the pooch for whatever reason, there is very little time to get out...which is why it has two hatches.  It also gives more flexibility to the launch vehicle and pad, enhancing its ability to fly on different boosters.
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