Update for Falcon V

[mikejz]

From SpaceX.com<br /><br />Falcon V Progress<br />The information on Falcon V that has been on the website for several months is now significantly out of date. Following discussions with customers, we decided earlier this year to make some important changes. <br /><br />We are switching from a dual Kestrel upper stage to a single Merlin upper stage. This has a major effect on mass to orbit due to improved mass fraction, higher specific impulse and better staging efficiency. The improved mass fraction results from having a pump-fed upper stage with thin tank walls and low helium requirements vs. pressure-fed with thick tank walls and high helium requirements. The higher specific impulse comes from the much higher chamber pressure of Merlin and much higher expansion ratio. The Merlin vacuum specific impulse is expected to be 340s vs. 325s for Kestrel.<br /><br />Other changes not included in prior numbers will also boost payload to orbit. During the development process, the Merlin engine has show itself capable of at least an 80,000 lb sea level thrust vs. the nominal 72,000 lb. Also, both the inter-stage and fairing will be made from a carbon fiber sandwich composite (vs. just the inter-stage in Falcon I), improving mass fraction. Following completion of the Merlin 1 qualification, we will begin work on a Merlin 2 with a sea level thrust target in excess of 100,000 lb as well as a slight increase in Isp. <br /><br />The estimated payload to orbit with the Merlin 2 engine, including both an Isp and mass fraction sandbag, is as follows:<br /><br />Orbit Payload <br />200 km, 28.5 deg 6020 kg / 13,260 lb <br />400 km, 51 deg 5450 kg / 12,010 lb <br />700 km, sun-synch 4780 kg / 10,530 lb <br />GTO, 9 deg 1920 kg / 4,240 lb <br />Escape velocity (0 C3, no kick stage) 1200 kg / 2,650 lb <br /><br />The above performance to GTO & escape can be improved significantly and the burnout g load reduced by using a kick stage, such as a Star motor from ATK. Note, the initial version of Falcon V

 

[najab]

><i>Speaking of Delta II, I thought they were to be stopped and replaced with Delta IV medium...</i><p>I think it is the Delta-3 that is being phased out. It never really was much of a commercial success anyway.</p>

 

[elguapoguano]

I'll have to check into this, but I thought it was Delta II that was being replaced as well. Never heard of the Delta III, I always thought it funny they went from II to IV... <div class="Discussion_UserSignature"> <font color="#ff0000"><u><em>Don't let your sig line incite a gay thread ;>)</em></u></font> </div>

 

[najab]

The Delta-3 is (was?) an intermediate step between the Delta-2 and Delta-4. <strike>They basically slapped a Russian engine on a Delta-2 body.</strike> I mis-spoke earlier, the Delta-3 used a Rocketdyne engine, on a beefed up Delta-2 core. The result was less than spectacular - well, that's not true the failures were quite spectacular (from a safe distance).

 

[backspace]

Speaking of those spectacular failures... anyone know where the video of those has gotten off to?

 

[propforce]

The Delta II is not being phased out. NASA really likes it for launching scientific payloads on them. <br /><br />Both Delta II and Delta III uses Rocketdyne's RS-27A engine for its 1st stage.<br /><br />Delta III was a Boeing internally funded project. It replaced the Delta II 2nd stage with a cryogenic 2nd stage (D-II has storable 2nd stage) that uses P&W RL10 engine (not Russian). It used the same 1st stage as D-II. The Delta-III failed in the first 2 launches. It has been discontinued.<br /><br />Delta IV replaced the D-III/D-II 1st stage with a cryogenic 1st stage with Rocketdyne's RS-68 engine, while keeping the D-III 2nd stage but made it bigger. In addition, it has option for liquid strap-on boosters and solid strap-on motors, and the choice of 4-meter or 5-meter diameter 2nd stage and fairing. Hence the option of medium, medium+, and heavy version. <div class="Discussion_UserSignature"> </div>

 

[mikejz]

It seems to be that the replacement of the engine in the second stage of a Non-Recoverable Merlin and assocated Turbopump will drive up the price from $12mil to maybe $17-$22 million in exchage for the greater lifting power.

 

[scottb50]

Why does it have to be non-recoverable? The Merlin can be restarted and seems pretty robust, it would make a good Tug, or transfer vehicle, if left in orbit. <br /><br />The biggest problem I see is refueling it. I would think it could be modified to LH and LOX though, then the only thing we need to launch to support it is water. <div class="Discussion_UserSignature"> </div>

 

[mikejz]

Only the 1st stage of the Falcon/Falcon V is recoverable and reusable. The second stage is expended in each launch (at it goes to orbit and recover would involve a TPS, etc). By using a more complex/expensive engine in the 2nd stage costs will rise.

 

[scottb50]

It goes to orbit is precisely my point. It's already in orbit, why not re-use it in orbit? <div class="Discussion_UserSignature"> </div>

 

[spacester]

It's a good point. Most people miss it, but I hope it will become common in people's thinking:<br /><br />A spent second stage is a potential orbital asset. It is a propulsion module. If it can be refueled, it can take your stuff to other places in space. It also is potential raw material for other projects. <div class="Discussion_UserSignature"> </div>

 

[mikejz]

Almost all the mass of a 2nd stage is fuel. So the only real way to make more use of it is to refuel it is to launch more fuel for it--thus another 2nd stage is required to launch it, and we are back to where we started from

 

[spacester]

Not quite true.<br /><br />Who says the fuel has to get there the same way the stage did?<br /><br />Maybe you find a way to get fuel there relatively cheaply; now you've got prospects of doing business with this asset. <div class="Discussion_UserSignature"> </div>

 

[scottb50]

But we have more capability in Space with every launch. Eventually we take engines back to Earth for overhaul and extended use and use the propellant tanks for something else. That sounds pretty easy. <div class="Discussion_UserSignature"> </div>

 

[mikejz]

True, but each on is in a different orbit--which takes propellent to get to each one.

 

[scottb50]

That sort of sounds like the mission statement for a Tug. A manned, or unmanned payload and the empty second stage would be picked up and taken to a central location. Tugs could also be used to orientate and slow return vehicles, then boosting back to a higher orbit for refueling and re-use.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[halman]

Scottb50,<br /><br />Please correct me if I am wrong, but upper stages which go into orbit typically enter very low orbits, which are not stable, having sections which encounter severe air resistance.<br /><br />Salvaging such upper stages would probably be feasible if a space tug were standing by on a low orbit which could be altered to allow interception, but hoping to collect such upper stages a few years down the road is wildly optimistic. Even when a space tug is available, the propellant needed to haul a spent second (or third) stage up to a stable orbit may be worth more than the spent stage, once the propellant is sent into orbit.<br /><br />If I remember correctly, the ideal mission profile has the spent upper stage barely rising beyond the edge of the atmosphere. I realize that very rarely will this occur, but it seems to me that it is pretty rare that a spent upper stage reaches a high enough altitude to survive very long. <br /><br />Motors for transfer to the Clarke orbit, or a planetary transfer orbit are an entirely different story, and someday a salvage program will have to be initiated to clean up all that junk. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[scottb50]

If you use the second stage of the Delta as an example it can be put in basically any orbit because it can be restarted. The only variable being the propellant load available at launch. <br /><br /> The amount of propellant needed to go from 200miles to 400miles, in the same orbit is much less than moving from one orbit to another. I would think the upper stage, used this way, could position itself and an attached payload to a fairly close orbit and a Tug could be used to do the critical menuevering and docking. This could allow it to be as simple as possible allowing more propellant and payload. On the other side of the operation a Tug could take a returning payload and put it into a proper descent, then power back to a stable orbit.<br /><br />Tugs would also provide the boost to Lunar and Mars missions as well as maneuvering in those orbits and return to LEO. By adding Tugs as needed payloads could be quite flexible and transits more economical.<br /><br />As you say junk is a big problem already and throwing away potentially useful things into the atmosphere is very uneconomical, especially if you want to operate commercially. <div class="Discussion_UserSignature"> </div>

 

[backspace]

Strolling over to OIG, there are HUNDREDS of upper stages in LEO and other various orbits... some going back to the early sixties. Many of these orbits will be stable for hundreds of years.