Corrections & errata.

Date: Sun, 10 Sep 1995 14:00:54 -0700
From: toad@ugcs.caltech.edu (Benjamin Lane)

Early Bird, TL-7 AROS (Airborne Refueled Orbital Shutte)

Specifications
Structural;
TL: 7
Airframe: Hypersonic STOL
Design Weight: 70,000kg
Price: MCr 13.06 

Thrust: 1 x 600 kN Turbofan w/ afterburner (900 kN`w/ aftb.)
	1   3 x 2500 kN Ramjet ( 75 tons thrust )
	   1 x 3000 kN LF Rocket 

Controls: Electronic, 1 x Cramped WS with REP, BLS
		Hydrazine jet attitude control system

Electronics: Weather Radar, FLIR, Inertial Nav, Gyro, Xpndr
		   2 x TL7 Flight Computers
		   3000 km Range Radio

Crew: 1 Pilot/Operator

Cargo Capacity: 15 m^3 Cargo Bay, 15,000kg Std. Payload

Fuel: 750kg Hydrocarbon Destillates Internal
	 11,000kg HRF Internal
	 Fitted to Carry 3 x 15,000 kg Drop Tanks

Performance; 
Configuration 1 (Turbofan Only, Empty Drop Tanks, HRF):
		Speed: Max 1000 km/h, Cruise 750 km/h,
			  Min 175 km/h. 
			  Effective G rating: 0.3
			  Takeoff: 1200m Landing:800m
			  Endurance: 1 hour
Configuration 2a (Afterburning Turbofan, Ramjet, Full Fuel):
		G: 0.78
		Endurance: 6 minutes
Configuration 2b (Ramjet, 66% Fuel + HRF ):
		G: 0.83
		Endurance: 6 minutes
Configuration 2c (Ramjet, 33 % Fuel + HRF ):
		G: 1.01
		Endurance 6 minutes
Configuration 3 (Rocket, 11,000kg HRF, 500 kg HCD):
		G: 0.5
		Endurance: 5 minutes

Effective Delta-V: 10 km/s ( Post-Refueling )

Semi-officially known as an ASSTO, "Almost Single Stage To Orbit" vehicle, the Early Bird requires only tanker support and a 2000 meter runway to reach orbit carrying a 15,000 kg payload. A common sight on low-tech worlds,it serves a variety of purposes, including satellite launch and maintenance, suborbital transport, space strike, 
and orbital interface shuttle.
To achieve orbit, the EB lifts off carrying enough fuel 
to rendez-vous with an airborne tanker at approx. 20 km 
altidtude and 900 km/h. This puts it above 85% of the atmosphere of a Terran-type world, thus greatly reducing 
the energy need to achieve LO. At this time, over 45 tons 
of fuel are transferred to the EB's drop tanks, while  afterburners are used to maintain altitude. When the fuel transfer is complete, the EB breaks away and begins to 
build up velocity and altitude using ramjets as well as its afterburner-equipped turbofan. When one-third of the fuel is 
emptied, one of the outboard droptanks is jettisoned. At this point, a special flap is used to compensate for the assymetric droptanks. When the turbofan begins to lose 
power it is shut down, and the EB relies solely on scramjet propulsion. As each successive drop tank is emptied it is jettisoned. The final exo-atmospheric insertion and deorbit burns are carried out using a liquid-fueled rocket. After deorbiting, the shuttle retains only approximately 500kg fuel for the turbofan to use during the landing phase.

Comment: OK, so with a lot of squeezing and fiddling it is
possible to get this thing to work. However, if you use the standard rules (FF&S, p 71) you will discover that this design produces only about 0.2 G-Hours from the ramjet/rocket. However, there is enough room to fuel the turbofan for several hours before refueling - thus producing as much as 0.6 G-Hours with the turbofan alone. This is not a good rule. Therefore I have applied the following rule changes;
a)`The 0.64 G-Hours requirement is scrapped - I use the < 10km/sec to orbit from the RealWorld (tm). 
b)Since the actual orbital burn starts from high altitude, most of the loss due to the atmosphere is neglected. 

This is not really the optimal way to treat this type of problem - it would be better to redesign the thrusters available, and add a more accurate table of the to-orbit
velocity requirements. Perhaps when I get the time, i.e. the summer of 2032 or so... 

Date: Sun, 10 Sep 1995 22:33:09 -0700
From: toad@ugcs.caltech.edu (Benjamin Lane)
Subject: Corrections & errata.

Apologies, apologies - I made a typo in the Early Bird stats. The thrusters
are not as powerful as I rated them.... the turbofan produces 6 tons of 
thrust, the Ramjets 75 tons, and the rocket 30 tons. sorry about that.
I feel like GDW, almost.

Oh, and regarding the comment about not using Tomahawks against the Serbs,
well, it would seem somebody has decided to escalate.
cheers,
/ben