Atlas V, Delta IV, Ariane 5, Proton, Hitacchi H-IIB all can launch between 19 and 23 tons to LEO. Why are they so similar in this respect?Is it because there isn't much demand for larger launches? Maybe it is enough for any reasonable spy satellite, or communication satellite to GEO? Or are there design reasons which dictate that costs increases more rapidly beyond that launch capability?
Also, the H-IIB's (which was designed to lift the HTV and its cargo) primary contractor is Mitsubishi, not Hitachi.
Quote from: TakeOff on 07/27/2014 09:22 pmAtlas V, Delta IV, Ariane 5, Proton, Hitacchi H-IIB all can launch between 19 and 23 tons to LEO. Why are they so similar in this respect?Is it because there isn't much demand for larger launches? Maybe it is enough for any reasonable spy satellite, or communication satellite to GEO? Or are there design reasons which dictate that costs increases more rapidly beyond that launch capability?I think that today it is geosynchronous satellites, both commercial and defense types, that play a dominant role in determining the capability of launch vehicles. That said, it is worth mentioning that both Proton and H-IIB were originally built for non-GEO work. H-IIB has so far only launched HTV missions to ISS. Proton, after derivation from a massive never-realized ICBM concept, was developed to launch Zond spacecraft (planned to be manned, but never attained) around the Moon. Today, of course, Proton and Ariane 5 share the bulk of the world's commercial GTO work while Atlas V and Delta IV are doing mostly the government work for which they were designed. Only a fraction of that work is to LEO. - Ed Kyle
Quote from: edkyle99 on 07/28/2014 02:46 amQuote from: TakeOff on 07/27/2014 09:22 pmAtlas V, Delta IV, Ariane 5, Proton, Hitacchi H-IIB all can launch between 19 and 23 tons to LEO. Why are they so similar in this respect?Is it because there isn't much demand for larger launches? Maybe it is enough for any reasonable spy satellite, or communication satellite to GEO? Or are there design reasons which dictate that costs increases more rapidly beyond that launch capability?I think that today it is geosynchronous satellites, both commercial and defense types, that play a dominant role in determining the capability of launch vehicles. That said, it is worth mentioning that both Proton and H-IIB were originally built for non-GEO work. H-IIB has so far only launched HTV missions to ISS. Proton, after derivation from a massive never-realized ICBM concept, was developed to launch Zond spacecraft (planned to be manned, but never attained) around the Moon. Today, of course, Proton and Ariane 5 share the bulk of the world's commercial GTO work while Atlas V and Delta IV are doing mostly the government work for which they were designed. Only a fraction of that work is to LEO. - Ed Kyle On the US side the EELVs were built to replace the Titian IV and Shuttle which had similar payload sizes.I wonder how much effect LV size has had on the mass of commercial satellites and will Falcon Heavy cause the creation of a new class of heavier and more powerful comsats.Some applications like satellite Internet seem to be limited in capacity by the size of the antenna , and the power of the transmitters.More spot beams and more power means higher data rates for customers.Then there's other markets such as 4K and 8K HDTV which need higher data.Yes you can use better compression but going too high of compression introduces artifacts which can defeat the entire purpose of the higher resolution.
I wonder how much effect LV size has had on the mass of commercial satellites and will Falcon Heavy cause the creation of a new class of heavier and more powerful comsats.
Nobody will build payloads for only a single LV.
Quote from: pippin on 07/28/2014 05:05 pmNobody will build payloads for only a single LV.That is a very good argument!I want to illustrate that idea as it inspires me, in terms of that 20 tons to LEO became a standard once, by coincidences pretty much unrelated to today's satellite "needs" and rocket economics. Super powers in a cold war just happened to balance each others to that level. After a while of having prioritized even bigger rockets, the race instead began to get hotter for bigger tanks. Or something like that. You can safely build a 20 tons to LEO satellite, because you have half a dozen competitors to launch it. But if there exists only one 50 tons to LEO launcher, then you need to have some trust in order to invest in a 50 ton satellite.
You can safely build a 20 tons to LEO satellite, because you have half a dozen competitors to launch it. But if there exists only one 50 tons to LEO launcher, then you need to have some trust in order to invest in a 50 ton satellite.
20 ton to LEO != 20 ton satellite.
Quote from: QuantumG on 07/28/2014 11:19 pm20 ton to LEO != 20 ton satellite.Why is this the case? I always thought the payload to LEO number was the maximum mass that could be put in LEO, and therefore an upper limit on satellite mass?
Thought Titan IV was built to launch shuttle class payloads that were banned from the shuttle hence the short lift time of that rocket .
Quote from: floss on 07/29/2014 07:19 pmThought Titan IV was built to launch shuttle class payloads that were banned from the shuttle hence the short lift time of that rocket .It was developed before Challenger. A production run of 41 vehicles from 1989 to 2005 is not defined as a short lifetime.