The long anticipated Falcon Heavy should fly towards the end of this year. Many people seem to believe that this launcher is going to be the answer to the PorkLauncher, big private payloads, launch costs, reliability, and all the other competition. I tend to think it can be a good launch vehicle without being any of those things.
Up until recently, I thought bolting three or more first stages together for larger payloads was close to a no brainer, especially if those stages are getting reused. I saw little problem with using up to seven stages bolted together. A few recent articles have made me question my previous opinion. One about Elon Musk discussing the difficulties of making three stages work together brought up a few interesting issues on the problem. Another by Rand Simberg going into some detail on dispatch reliability and complexity issues that I have not previously considered.
I have been skeptical of some of the claims made by people from outside the company since they started posting them. There are some that insist that the F9H is going to get costs per pound down to $50.00 or less. I still believe it is too early in the game to confidently predict such prices. It should be possible to be a fan of the SpaceX accomplishments without being a wild eyed fanboy that thinks Elon walks on water in the liquid phase. There are some more debatable points I have met relatively recently.
The F9H will be the death of SLS/Orion as soon as it flies seems to be fairly popular. This would seem to be against the history of government procurement programs. The logical arguments against developing the SLS/Orion system were as valid a decade ago as they will be when F9H flies. If it was about logic, a crew capsule would have been flying on an EELV before the Shuttle was retired. An orbital depot would have enabled any mission the SLS/Orion is purported to have. The SLS/Orion may go out with a whimper in the next decade. It is politically nearly impossible that it will be in direct response to the early flights of the F9H. A politician has a primary job of getting elected, and the SLS/Orion systems will last as long as they contribute to that primary job.
There seems to be a lot of belief that huge private payloads will be ready to go as soon as the LV is available. I don’t think this matches payload history on current launch vehicles. Ariane5 and Delta Heavy don’t seem to have a backlog of full weight payloads. It is common for there to be two or more full size satellites in an Ariane launch. For that matter, F9 doesn’t seem to have payloads that come close to the advertised capability. I believe that the F9H will be an infrequent launcher of specialty payloads that are just a bit more than the F9 and competitors can handle. Once proven, it is likely that the F9H will have single digit flights per year. Elon has mentioned that one of the reasons for the delays in getting the F9H on line is that there is little demand for it. Plenty of others have mentioned that the steadily increasing capability of the stock F9 also cuts into the demand for the heavy.
Launch costs are the choke point on space development and always have been. Many people believe that the F9H is going to solve this problem. The advertised prices seem to support their opinions. The normal method of figuring launch costs use dollars per pound as the metric of affordability. Dividing maximum payload by launch price supports the belief in the F9H as the frontier enabler. My skepticism comes from some recent articles discussing technical issues I hadn’t previously considered. When the rubber hits the road, all three of the first stages in the F9H have to go through the same level of processing as in a normal F9 flight, plus be integrated into a complete F9H. The additional level of work required to make three stages into one makes it likely that the actual launch prices per pound will end up being higher for the F9H than for the stock F9.
I expect the F9H to be a fairly reliable launch vehicle. I can’t see it matching the parent vehicle in that respect. There will be some risk associated with three cores working together with aerodynamics, vibration, and structural loads that don’t apply to the F9. There will be the additional risk of individual reliability of four stages instead of two in the F9. Very low probability events per stage will have twice as many chances to manifest in the larger vehicle. There is also the likelihood IMO that the F9H will have a much lower flight rate than the stock F9 which could lead to a bit less proficiency in catching the minor issues. Bottom line is that unless the F9H flies a lot, there will always be some question as to its’ reliability relative its’ parent vehicle.
I find the opinions often expressed that the F9H will sweep the competition to be less well thought out than they should be. As long as there are many reasons to launch a variety of sizes and orbital inclinations, there will be a variety of launch vehicles to serve the various niches. From national launchers to smaller proprietary payloads to personal animosities, there will always be reasons to have other launchers by other countries and companies.
At the end of the day, I expect the Falcon 9 Heavy to be a good launcher with fair reliability. I don’t expect it to be the greatest or the cheapest, just a good machine for the intended purpose.