We should expect their prices to come down once their launch rate (after internal use, e.g., Starlink) approaches or exceeds the rate of sales, and not before.
It strikes me as likely that the market is a lot more elastic at the low end (especially cubesats) than the high end (large GTO).
That seems a little strong. SX found a solution using grid fins, but that doesn't preclude the possibility of doing it without them.
In a high-risk business with big R&D and capital barriers to entry, expendable's reduced the time and cost to get something flying could easily be more attractive than reusable's marginal cost reduction.
Quote from: ExastroIn a high-risk business with big R&D and capital barriers to entry, expendable's reduced the time and cost to get something flying could easily be more attractive than reusable's marginal cost reduction.Here's a shocker. If you build what you always built you tend to get what you always got.The interesting implication of this is that the F9 booster is not that much different to any other LRE booster on a TSTO rocket.IOW this could be done by any 1st stage, if the mfgs were prepared to take the risk with their own money of making the necessary mods.Let's see which of them will.
Electron would likely be fairly straightforward to upgrade for RTLS, since it has multiple engines that can probably be modified for deep throttling (electric pumps) and restart (spark igniter) without much trouble, and a reasonably large upper stage depressing the staging velocity. But Ariane 6 or Vulcan? Not happening, even if they wanted to.
Quote from: envy887 on 06/11/2018 01:34 pmElectron would likely be fairly straightforward to upgrade for RTLS, since it has multiple engines that can probably be modified for deep throttling (electric pumps) and restart (spark igniter) without much trouble, and a reasonably large upper stage depressing the staging velocity. But Ariane 6 or Vulcan? Not happening, even if they wanted to.Electron is too small to retrofit for first stage recovery. This is a tiny rocket, by previous standards. It only weighs 12.55 tonnes at liftoff. That is less than half of the weight of a Falcon 9 first stage with no propellant loaded. It is also less than half the GLOW of a Falcon 1. Electron can only lift 150 kg to sun synchronous low earth orbit. That capability would be lost, probably all of it, to the needs of a propulsive-stage-recovery system added to the existing stage. To maintain its listed capability while adding stage recovery, Electron would have to grow substantially in liftoff mass, which would in turn require much more liftoff thrust, which either means a new higher thrust engine or a larger number of existing engines (at least a dozen, maybe more) on what would have to be a fatter, taller stage.There's also the question about the reuse of the composite pressurized tanks. - Ed Kyle
The whole booster probably masses around 500 kg as it is...
Quote from: envy887 on 06/11/2018 05:46 pm The whole booster probably masses around 500 kg as it is...Much heavier than that I expect. The engines alone with electric motor pumps and batteries are together going to weigh something like 300 to 450 kg. My guess for first stage burnout mass is roughly 950 kg, which would include residuals. - Ed Kyle
Quote from: edkyle99 on 06/11/2018 06:36 pmQuote from: envy887 on 06/11/2018 05:46 pm The whole booster probably masses around 500 kg as it is...Much heavier than that I expect. The engines alone with electric motor pumps and batteries are together going to weigh something like 300 to 450 kg. My guess for first stage burnout mass is roughly 950 kg, which would include residuals. - Ed Kyle Old RocketLab interview suggests a 1090 kg total dry mass, of which 15-20% is probably the fairing and upper stage. So 950 kg is probably a lot closer than 500 kg. But adding 500 kg for recovery hardware seems pretty excessive for such a small stage, they could probably do it for less than half that.http://www.parabolicarc.com/2014/07/29/rocket-lab-announces-small-satellite-launcher/That still lighter and a lot smaller than the F9 fairing half. And it appears they have quite a bit of excess thrust already, if they deem a stage stretch worthwhile. Liftoff TWR is about 1.55.
Quote from: LouScheffer on 06/08/2018 10:48 pmQuote from: cferreir on 06/05/2018 06:37 amWhat i'm really curious about is how Rocket Labs can:2. Absorb the battery weight penalty (for the rutherford engine)and still be competitive.....The batteries are not completely dead weight. They avoid the need to run some of the fuel through the gas generator, which will raise the ISP compared to a gas-generator cycle like the Merlin. The details of this trade would require some thought, but it's definitely not as bad as just adding the mass of the batteries.Here's some people who have given this some thought: Performance assessment of electrically driven pump-fed LOX/kerosene cycle rocket engine: Comparison with gas generator cycle They conclude:QuoteUnder the same operating conditions for both cycles, the hypothetical LEO mission analysis revealed that the ElecPump cycle has a payload capability that is only 2.1% to 3.1% less than that of the GG cycle for the 3 MPa case.See also ELECTRIC FEED SYSTEMS FOR LIQUID PROPELLANT ROCKET ENGINES for similar conclusionsSo a relatively small performance hit, but a drastic simplification of the engine.
Quote from: cferreir on 06/05/2018 06:37 amWhat i'm really curious about is how Rocket Labs can:2. Absorb the battery weight penalty (for the rutherford engine)and still be competitive.....The batteries are not completely dead weight. They avoid the need to run some of the fuel through the gas generator, which will raise the ISP compared to a gas-generator cycle like the Merlin. The details of this trade would require some thought, but it's definitely not as bad as just adding the mass of the batteries.
What i'm really curious about is how Rocket Labs can:2. Absorb the battery weight penalty (for the rutherford engine)and still be competitive.....
Under the same operating conditions for both cycles, the hypothetical LEO mission analysis revealed that the ElecPump cycle has a payload capability that is only 2.1% to 3.1% less than that of the GG cycle for the 3 MPa case.
As a note Over in the electric pumped rocket cycle thread are some rough calculations I did on a F9 clone with Rutherford engines.In short - if you take a F9, and replace the Merlins with Rutherfords, you lose four tons payload to LEO, and two or so tons to GEO.Slight modifications (ditch most of the rutherfords on S2 as you get to 20 tons mass) may get it closer to one ton penalty.It is also unclear if you can't lose other weights in the stage, potentially reducing this penalty. If Rocketlabs was to go with reusable there are several reasonable arguments as to why it may be easier than F9.Starting with much better throttleability and thruster response (50-100% step in thrust should be well under 100ms), and much, much more divided thrust for S1, with no need for gimballing potentially.
That still lighter and a lot smaller than the F9 fairing half. And it appears they have quite a bit of excess thrust already, if they deem a stage stretch worthwhile. Liftoff TWR is about 1.55.
It would be funny to see them partner with Tesla. There would be nobody better to improve battery efficiency and packaging. They know quite a bit about electric motors too.