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Author Topic: Sprint Ferry Overview  (Read 25160 times)
aftercolumbia
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« on: June 25, 2006, 01:41:45 PM »

Not to be confused with After Columbia's original Delta Sprint at http://aftercolumbia.tripod.com/deltasprint/ ; Sprint is based on it, increasingly loosely.

The Sprint ERV Mk. 1 is currently under development by myself, Brian Heick and Seth Hollingsead at the Orbiter Mars Direct Program, which also resides at Meadville Space Center.

The Delta Sprint was intended to substitude the STS-107 stand-down by being a crew ferry for three members that could be developed on the same budget and schedule as the STS-33 stand down after the Challenger disaster (as Delta Sprint was characterized before the extent of the STS-107 stand down was known.)  The basic philosophy was to launch it on the most reliable US commercial booster that could be sought and then built to survive its failures as a commercial rated booster rather than man-rating it.  The booster selected was the Delta II.  Originally the Delta Sprint had intended to use the Fregat upper stage to assist its service module in rendezvous maneuvers, thus saving on Service Module development...then I found out that was a pretty dumb idea.  The lessons learned from Delta Sprint have been carried forward into the Sprint Ferry.

The Sprint Ferry amasses a total of about 8000kg at booster cutoff breaking down something like this (updates pending)

Orbital:
Descent Module: 5000kg
Service Module: 3000kg

Ascent:
Service Module Fairing: 1200kg
Payload Escape Stage: 1500kg

The current front runner for booster is the Greenstar 3150.  These are the other current front running details:

- Pressure Bearing Safety Factor: 2.0
- Compression Loads Safety Factor: 1.5
- X-axial Load Factor based on worst case survivable abort entry: 20g
- Service Module Main Propulsion: Diaphragm/regulated GN2 fed monopropellant hydrazine; four main motors
- Service Module RCS: same supply, 12 secondary thrusters
- Descent Module RCS: Diaphragm/blowdown GN2 fed monopropellant hydrazine; 16 thrusters linkable to SMRCS supply prior to SM separation
- Descent Module Payload Escape Stage: Four solid motors located under RCS pods in Heick 0606 model
- Service Module Backup Maneuver Motor: Solid motor, probably Star 30 class, located on the Service Module X-axis.  This motor provides backup deorbit capability to the SMMP and also provides the abort capability after the Payload Escape Stage has been jettisoned.
- Service Module constructed of 7075-T73 aluminum alloy, Descent Module structures made of 2024-T6 (machinability concerns, as DM main structure is very complicated.)
- Descent Module Thermal Protection System uses RCC for the base heatshield, and AFRSI throughout the rest of the craft.  These are backed up by ablatives to allow survival of up to an 50mm2 breach in the main material.
- The Service Module possesses a protective impact shield to guard the main heatshield of the Descent Module from debris hazards during an uncommanded abort.
- An Orbital Docking System compatible with the current Shuttle/ISS system is carried in the nose in clamshell doors.
- Recovery is by a ram-air inflated parasol (similar to parachutes and paragliders used by their respective sports, only much larger) and airbags.
- Backup is provided by water recovery, reserve parachutes and the David Clark S1035 Advanced Crew Escape System, the suit and individual parachute currently used by Shuttle astronauts during launch and entry.
- Design goal for the probability of all crew members surviving any given mission without major injury is 99.99%
- Expected probability for a mission being completed normally is 98.50%, 1.00% deficit from booster failure, the remaining 0.50% from the spacecraft and mission on orbit.

Terry Wilson
After Columbia Project
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blackflowers18
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« Reply #1 on: May 27, 2009, 09:36:31 PM »

It could be done the  Delta Sprint had intended to use the Fregat upper stage to assist its service module in rendezvous maneuvers.
« Last Edit: May 29, 2009, 08:50:03 AM by Tschachim » Logged
aftercolumbia
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« Reply #2 on: January 05, 2011, 07:01:40 PM »

I discovered that the Fregat upper stage was far too heavy to ascend on the Delta II, at least in any low energy mission.  It's been a few years, and at the time I made the original post, Atlas V 402 was the leading vehicle.  I prefer a booster without ascent SRMs because you can't safely shut them down.  Today, I'd say that Falcon 9 is the booster of choice.  Also, the SpaceX Dragon is so close in characteristics to the Sprint, that it really doesn't stand much of a chance in the current market.

I have given some fairly recent thought to Sprint, including the story of its harrowing first flight in the world of Featherwing Love:

http://www.bookrix.com/_title-en-terry-wilson-breakwire
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