At the end of 2003 ILAT issued the following press release announcing some significant changes to their design:
[quote author=www.ilat.co.il (website now defunct)]
Tel Aviv, Israel (Dec 31, 2003) – IL Aerospace Technologies (ILAT) has unveiled today its new X Prize competition vehicle design now called “NEGEV” (formerly named NEGEV-5).
Aside from the name, the vehicle’s configuration has gone through several design iterations in the last 3 months. These modifications originated from as fresh set of innovative concepts derived from ILAT’s recently formed technical team and advisory committee, which now comprises Mr. Dov Raviv (former head of Israel Aircraft Industries MLM division); senior aeronautical engineers from AERODAN Systems; and Israeli astronaut IAF Lt. Col. Itzak Mayo (mission specialist backup to the late Col. Ilan Ramon during STS-107).
After several brainstorming and design review sessions, ILAT opted to keep their original concept of using a balloon as a first stage, but not without significant changes. “The advantages of using such launch platform clearly outweigh the disadvantages in terms of simplicity ”, said Dov Chartarifsky, ILAT Founder and CEO. “However, in order to meet our new requirements for altitude takeoff, we decided to use a smaller more robust hot-air/helium mixed design rather than the larger, more fragile, polyurethane super-pressure design”.
Besides the balloon configuration, ILAT made a more radical decision to change the rocket motor design from a hybrid type that is yet to be developed, to a commercially available solid motor design with an impeccable record for safety and reliability. This radical change was necessary to give ILAT a fighting chance at winning the X Prize before the end of 2004 without sacrificing safety. The downfall of the solid motor is that it is not reusable, and therefore it will have to be replaced on the second flight attempt. This will not violate any X Prize rules since the burnout weight of the rocket motor is less than 10% of the vehicle’s total dry weight. “We haven’t discarded the hybrid motor concept, in fact, we plan to develop and qualify a hybrid motor before entering the commercialization phase of our program. We regard this to be a gutsy decision on our part, but we feel confidant in our ability to fly our vehicle before the X Prize deadline expires, continued Dov Chartarifsky.
Rationale of the new configuration choice
- The rocket motor has been mounted far from the capsule to protect the passengers in case of motor malfunction.
- The fore cone has been configured to decrease drag and allow a lower ignition altitude of 10 Km
- The upper part of the capsule will now be used to house the parachutes
- The attitude of the capsule will remain the same during reentry. This will remove the requirement of maneuvering the capsule 180 degrees for reentry, and will keep the acceleration direction acting on the passengers the same as during the ascent
- The lower part of the capsule will be the deceleration and heat absorbing element during reentry
- During landing into the sea, the stability of the flotation will be ensured by the low ballast that the rocket motor casing will provide
- The need for a large polyurethane balloon can be eliminated since the vehicle can now be launched from a lower altitude. This minimizes the drift causes by jet stream and other environmental elements.
- Launching the vehicle from 10 Km provides a more manageable altitude that will result in lower cost, simpler balloon and vehicle recovery, and quicker implementation.
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A revised PDF containing details of the revised Negev MK II vehicle was produced in Januray 2004 (attached and obtained from www.ilat.net, also now defunct). The revised vehicle and mission specs it includes are:
VEHICLE SPECIFICATIONS
Name: Negev
Length: 10 meters (32.8 feet)
Diameter: 2.5 meters (8.2 feet)
GTOW: 3386 Kg (7464 lbm)
Dry Weight: 1116 Kg (2460 lbm)
Crew Environment: Pressurized cabin
Payload Capacity: 270 Kg (595 lbm)
No. of Engines: 1
Propulsion System: Solid Rocket Motor
Fuel: Solid
Total Thrust: 77.8 kN (17,500 lbf)
Reaction Control System: TBD
MISSION SPECIFICATIONS
Launch Site: Land or surface ship
Ascent Method: Balloon to rocket launch altitude
Ascent Duration: 45-60 min
Altitude at Rocket Ignition: 10.0 Km (32,808 ft)
Orientation at Rocket Ignition: 70° to 80° pointing up
Max. Acceleration Force on Ascent: 4.3 G
Altitude at Rocket Engine Cut-off: 50 Km (164,142 ft)
Time at Rocket Engine Cut-off: 95.6 sec
Max. Speed: 1165.5 m/s (2,607 mph) or Mach 3.54
Max. Altitude: 120 km (393,701 feet)
Time in Weightless Conditions: 236.9 sec
Reentry Method: Angular free fall
Acceleration Forces on Descent: -5.81 G
Landing Method: Pyrotechnically deployed drogue and main chute to water landing
