Doesn't the cone-shaped aft end also affect aerodynamics?
Here's a report from 2010 on man-rating the Ariane 5:
French govt study backs Orion Ariane 5 launch.
By Rob Coppinger on January 8, 2010 4:45 PM
http://www.flightglobal.com/blogs/hy...01/french.html
Gives 5 billion Euro as an upper bound only (and also some confusion; is it millions of dollars, or billions, for the lower figure? Did the dollar/Euro exchange rate just go wild for a bit there?).
Furthermore, it does not name a source beyond that 'in the blogosphere and print media'. It would be useful to note where this was said in the blogosphere, or by whom...
Man-rating a 3-stage vehicle with two large solid rocket boosters attached is a much more complicated process than man-rating a single stage liquid fueled vehicle. As a point of comparison the Atlas V base version without solid side boosters is planned to be used to launch the Boeing CST-100 and DreamChaser. Lockheed has said man-rating it is essentially complete at very little additional cost, even though it wasn't designed for manned launch.
Usually
building a new vehicle is more expensive than simply human-rating an existing one. Unless I'm mistaken, the Ariane 5 is a
two-stager with boosters (though it depends on the definition of stage- the boosters could be considered an effective first stage). Also, unless something has changed in the interim, the CST-100 is actually meant to be launched by the Atlas 412- which has a single small strapon SRM.
Furthermore, one would also imagine that a vehicle originally designed for human-rating (Ariane) would be cheaper than one not originally designed for human-rating (Atlas). If the human-rating of Atlas V is going along as smoothly as one might expect, than one would imagine that the human-rating of Ariane would be similarly easy, if not more so, and similarly inexpensive.
It should be pointed out that a good deal of the cost lumped together with human-rating may not involve the actual engineering or certification aspect, but instead be related to infrastructure alterations- to allow for crew access arms, etc.
It should be pointed out that your vehicle will require considerable infrastructure alterations from the Ariane 5- not only will it need to be supported differently on the pad, it will likely need alterations to the flame trench and/or ground starting equipment, as well as the vehicle integration equipment.
The Japanese space agency JAXA showed with the development of the H-IIB launcher from the H-IIA, that adding a second cryogenic engine can cost only in the range of $200 million.
Source please.
About the thrust-weight ratio of the Ariane 5 core with a second Vulcain, I discussed before the plan was to use the lighter Ariane 5 "G" version. With two Vulcain engines, this will have a T/W of about 1.1, within the range common for liquid fueled rockets.
That's odd. Using figures for Ariane 5
here and figures for Vulcain [ame="http://en.wikipedia.org/wiki/Vulcain"]here[/ame], giving a total mass of 170 tons, plus 1.3 tons for the extra engine, and 7 tons for the Dragon spacecraft (here, extra thrust structure mass, as well as other vehicle structure mass, any fairings or connection rings, and propellant and provisions necessary for the Dragon spacecraft, are neglected), and a total sea level thrust of 1800 kN, I get a TW of barely 1.03.
Only if the figures are assumed to be in short tons, do things translate to a TW of 1.1 (over 1.1, actually- it's more like 1.13).
This page gives mass in metric units, and lists the total mass of the Ariane 5G core as 170.8 tons- indicating that the TW of 1.03 is appropriate.
Add extra mass as is required, and the TW will drop even further.
Another problem is an excess of thrust later in the flight- this problem affects all SSTOs without deep throttling or sequential engine shutdowns. To my knowledge, the Vulcain has no throttle capability. Taking the dry mass from the above calculation and doubling it for good measure, we have a terminal acceleration of 6.5G. Lower masses endure even higher G forces- something like 13G acceleration near engine shutdown, for a 21 ton dry mass. To put this in perspective, acceleration limitations for human-rated vehicles are usually put at around 4G.
27 billion Yen are currently 350 million USD. The Ariane 5 did cost already 8 billion USD in its initial development.
Would be interesting to compare the Ariane 5 development cost with the original development cost of the H-II/H-IIA.
