Great job SpaceX

On 6/2/2020 7:50 AM, Jeff Findley wrote:
An in-line design is more likely to transmit vibrations straight from
the engine to the capsule with the propellant acting to dampen a bit of
that out. Remember the horrible time NASA had trying to dampen the
vibrations of Ares I? That's about as bad as it gets. Giant SRB in-
line with a smallish upper stage.

Jeff


OMG yes. You have a bad tooth filling or a kidney stone? Take a
sub-orbital ride in the Ares I. Will substitute the 2nd stage with a
mass simulator of solid steel. :::---OOO

Dave

On Tuesday, June 2, 2020 at 7:34:35 AM UTC-4, Jeff Findley wrote:
In article ,
says...

Saturn 1B was huge and it dwarfed the Titan 3C, which was a large rocket in its
own right.

Here's a picture I found on Reddit showing various crewed launch
vehicles to scale:
https://www.reddit.com/r/nasa/commen...asa_human_spac
eflight/

Falcon 9 really is a beast. It doesn't look like much compared to the
Saturn IB, but to quote Han Solo: "She may not look like much, but
she's got it where it counts, kid."

But when you compare Saturn V to SLS 1A and SLS 1B (remains to be seen
if the EUS for 1B will ever be built), SLS falls short in the
performance department. NASA keeps boasting that SLS is "more
powerful" than Saturn V, but that's only liftoff thrust. The fact is
those SRBs do have high thrust, but their casings are *heavy* and their
ISP is terrible, leading to worse performance compared to something like
the Saturn V's first stage (LOX/kerosene like Falcon 9).

FWIW, Wikipedia has these figures, whereby payload to LEO is slightly
higher for SLS Block 2.

The Space Launch System (SLS) is a US super heavy-lift expendable launch
vehicle. Payload to LEO. Block 1: 95 t (93 long tons; 105 short tons);
Block 2: 130 t (130 long tons; 140 short tons)

Fully fueled, the Saturn V weighed 6.5 million pounds (2,950,000 kg) and
had a low Earth orbit payload capacity originally estimated at 261,000
pounds (118,000 kg), but was designed to send at least 90,000 pounds
(41,000 kg) to the Moon.

In article ,
says...

On Tuesday, June 2, 2020 at 7:34:35 AM UTC-4, Jeff Findley wrote:
In article ,
says...

Saturn 1B was huge and it dwarfed the Titan 3C, which was a large rocket in its
own right.

Here's a picture I found on Reddit showing various crewed launch
vehicles to scale:
https://www.reddit.com/r/nasa/commen...asa_human_spac
eflight/

Falcon 9 really is a beast. It doesn't look like much compared to the
Saturn IB, but to quote Han Solo: "She may not look like much, but
she's got it where it counts, kid."

But when you compare Saturn V to SLS 1A and SLS 1B (remains to be seen
if the EUS for 1B will ever be built), SLS falls short in the
performance department. NASA keeps boasting that SLS is "more
powerful" than Saturn V, but that's only liftoff thrust. The fact is
those SRBs do have high thrust, but their casings are *heavy* and their
ISP is terrible, leading to worse performance compared to something like
the Saturn V's first stage (LOX/kerosene like Falcon 9).

FWIW, Wikipedia has these figures, whereby payload to LEO is slightly
higher for SLS Block 2.

The Space Launch System (SLS) is a US super heavy-lift expendable launch
vehicle. Payload to LEO. Block 1: 95 t (93 long tons; 105 short tons);
Block 2: 130 t (130 long tons; 140 short tons)

I was only looking at Block 1A and Block 1B because I seriously doubt
Block 2 will ever be funded. Boeing is way behind on designing the
Exploration Upper Stage which is what makes Block 1B different than
Block 1A. I doubt we'll ever get to the point that Block 2 development
will be funded, let alone completed.

Fully fueled, the Saturn V weighed 6.5 million pounds (2,950,000 kg) and
had a low Earth orbit payload capacity originally estimated at 261,000
pounds (118,000 kg), but was designed to send at least 90,000 pounds
(41,000 kg) to the Moon.

And if you looked at Saturn V upgrades (seems fair if you're comparing
to Block 2 which is a *long* ways off), I'm sure an uprated Saturn V
using upgraded engines (which were in the works) and some solid or
liquid rocket boosters would beat an SLS Block 2 in LEO payload.

Here's a cite to a study:

http://www.astronautix.com/data/satvint.pdf

From above (page 43, chart on page 44):

SAT-V-25(S) two stage payload capability to 100 nautical mile
orbit is almost 494,000 pounds

So, a similarly upgraded Saturn V would have had nearly twice the
payload to LEO as SLS Block 2.

I don't think this comparison is unfair. If SLS Block 2 can get
"advanced solid rocket boosters" that are only notional at this time,
why can't Saturn V get similar upgrades as well?

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

In article ,
says...

Smoothness of ride:

Wouldn't the "complaint" be due to the Merlin engine for stage 2 being
an awfull lot closer to the crew than the OMS or SSME engines on Shuttle
were?

How close it is (distance) doesn't matter as much as the structural mass
(e.g. the external tank itself and the orbiter itself) and liquid mass
(propellant in the external tank) which reduces the vibrations by the
time they get to the crew. The shuttle orbiter, plus external tank,
plus propellant that was left after SRB separation was *a lot* more than
a Falcon 9 upper stage and a Dragon 2. The space shuttle system was a
real porker in terms of dry mass.

Would the fact that the Shuttle was coated in tiles/blankets also deaden
some of the vivration compared to Stage2, Trunk and Dragon2?

No, those tiles/blankets are extremely light. They'd do little to
nothing to dampen vibrations being transmitted directly from the ET into
the orbiter's structure via the external tank attachment points (hint:
those attachment points transferred a lot of force from the orbiter,
where the SSMEs were, to the heavy external tank).

Or is the "complaint" really due to engine characteristics?

I'm not sure it's a complaint so much as an observation. Things that
are different, just aren't the same.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On 2020-06-03 8:44, JF Mezei wrote:
Smoothness of ride:

Wouldn't the "complaint" be due to the Merlin engine for stage 2 being
an awfull lot closer to the crew than the OMS or SSME engines on Shuttle
were?

Naively I would expect that in a three-engine system like the Shuttle,
where each engine provides 1/3 of the thrust, combustion irregularities
occur independently in each of the three engines, which means that they
are reduced by a factor of 3 compared to irregularities in the single
engine in the Falcon-9 second stage.

That is, except for Pogo, but AIUI this "roughness" of the second-stage
Crew Dragon ride is not Pogo.

--
Niklas Holsti

niklas holsti tidorum fi
. @ .

On 2020-06-03 8:29 AM, Jeff Findley wrote:
In article ,
says...

Smoothness of ride:


[snip]

Or is the "complaint" really due to engine characteristics?

I'm not sure it's a complaint so much as an observation. Things that
are different, just aren't the same.

Jeff


I agree with Jeff on this. I would not characterize what Doug said as a
"complaint", but an observation. The reasons for that have already been
discussed.

I suspect if/when Starship flies, you'll see possibly even a smoother
ride on it, mainly due to it's mass. Hopefully it flies soon enough with
crew that we can get folks who have flown on both it and the F9 to compare.

Dave

On 2020-06-02 7:50 AM, Jeff Findley wrote:
In article , says...

....


I'd guess the Saturn IB and Saturn V would be a smoother ride (same
upper stage really), simply because LOX/LH2 likely makes complete mixing
easier resulting in more complete combustion. But, it certainly would
be more apples to apples than the shuttle due to the in-line stage
design and the single engine. The shuttle had that giant, heavy, ET
structure hanging off the side that likely dampened some of the
vibrations (it certainly did when the SRBs were firing!).


I am going to disagree here a bit with you Jeff. As I understand it
there was still some POGO with the Saturn 5 Stage 1. I would expect the
higher it got and the less the fuel mass the worse it might have become.
Contrary facts always welcome. Contrary opinions always greeted with
skepticism. :-)

Also understand from what I've read MECO and stage separation of the
first stage was also a bit of a jolt. After that, I believe things
smoothed considerably as they went to LH2/LOX engines. The Saturn 5
second stage was a marvel and largely ignored (unfortunately).

Off the top of my head I count 5 crewed Apollo flights using the Saturn
IB: Apollo 7, the 3 Skylab missions and Apollo/Soyuz. The last flight of
a Saturn 5 was to launch the Skylab space station.

Dave

On Wednesday, June 3, 2020 at 8:24:24 AM UTC-4, Jeff Findley wrote:

And if you looked at Saturn V upgrades (seems fair if you're comparing
to Block 2 which is a *long* ways off), I'm sure an uprated Saturn V
using upgraded engines (which were in the works) and some solid or
liquid rocket boosters would beat an SLS Block 2 in LEO payload.

Here's a cite to a study:
http://www.astronautix.com/data/satvint.pdf
From above (page 43, chart on page 44):
SAT-V-25(S) two stage payload capability to 100 nautical mile
orbit is almost 494,000 pounds

Four solid rocket boosters added around the first stage. 100 seconds of
burn time and total of 4.45 million pounds of thrust.

Yeah, that would seriously increase the lifting capacity of the Saturn V!

Probably should have gotten its own name, like Saturn X.

So, a similarly upgraded Saturn V would have had nearly twice the
payload to LEO as SLS Block 2.

I don't think this comparison is unfair. If SLS Block 2 can get
"advanced solid rocket boosters" that are only notional at this time,
why can't Saturn V get similar upgrades as well?

Given all the questions about using solid rockets for manned space flight
back then, probably zero chance of getting it man-rated by the 1970s.

May have had serious design issues even for unmanned flights.

On 2020-06-03 11:02 AM, Scott Kozel wrote:
On Wednesday, June 3, 2020 at 8:24:24 AM UTC-4, Jeff Findley wrote:

And if you looked at Saturn V upgrades (seems fair if you're comparing
to Block 2 which is a *long* ways off), I'm sure an uprated Saturn V
using upgraded engines (which were in the works) and some solid or
liquid rocket boosters would beat an SLS Block 2 in LEO payload.

Here's a cite to a study:
http://www.astronautix.com/data/satvint.pdf
From above (page 43, chart on page 44):
SAT-V-25(S) two stage payload capability to 100 nautical mile
orbit is almost 494,000 pounds

Four solid rocket boosters added around the first stage. 100 seconds of
burn time and total of 4.45 million pounds of thrust.

Yeah, that would seriously increase the lifting capacity of the Saturn V!

Probably should have gotten its own name, like Saturn X.

So, a similarly upgraded Saturn V would have had nearly twice the
payload to LEO as SLS Block 2.

I don't think this comparison is unfair. If SLS Block 2 can get
"advanced solid rocket boosters" that are only notional at this time,
why can't Saturn V get similar upgrades as well?

Given all the questions about using solid rockets for manned space flight
back then, probably zero chance of getting it man-rated by the 1970s.

May have had serious design issues even for unmanned flights.


I took a cursory look at this document. There were also liquid fueled
strap-on options studied as well. The Saturn V 23L and Saturn V 24L. The
23L variant used pairs of "standard" F1s in each of four strap-on liquid
"pods" and the 24L used pairs of "uprated" F1s in four strap-ons and an
"advanced" engine for the upper stages. The document mentions aerospike
engines and maybe so, but there were also ideas kicking around at the
time for a higher performance J2 as well.

The 24L didn't make it past phase 1 study but, the 23L got a rating in
this document of 579,000 lbs (289.5 short tons) to orbit (2 stage
configuration) and 220,000 lbs (110 short tons) I presume to the moon (3
stage configuration). Presumably the 24L variant with the higher thrust
F1s could have done even better.* Let's be conservative and estimate
first launch by 1975 (this document was written in 1966 and predicted a
1973 ready date). My date includes assuming mobile launch platform
(known as MLs in the Apollo era) modifications and other pad
modifications also needed. But at the time Wikipedia says NASA had three
MLs, so NASA should have been able to dedicate one to support this
configuration.

Compare this to the also non-extant SLS Block 2 at 280,000 lbs (140
short tons) to LEO.

What a monster this could have been. You're gonna need to move further
back... What other country in the world (besides us) would have so
thoroughly blown this advantage in rocketry? We're talking nineteen
seventy freaking five!

Dave

*There's a tantalizing paragraph on page 9 that ends:

"The liquid pod strap-on concept, with uprated F-1s and advanced engines
in the second stage (SAT-V-24(L)), achieved payloads to 960,000 lbs.
[480 short tons] to 100 nautical mile Earth orbit when stage and total
vehicle length restrictions were relaxed."

In article ,
says...

On Wednesday, June 3, 2020 at 8:24:24 AM UTC-4, Jeff Findley wrote:

And if you looked at Saturn V upgrades (seems fair if you're comparing
to Block 2 which is a *long* ways off), I'm sure an uprated Saturn V
using upgraded engines (which were in the works) and some solid or
liquid rocket boosters would beat an SLS Block 2 in LEO payload.

Here's a cite to a study:
http://www.astronautix.com/data/satvint.pdf
From above (page 43, chart on page 44):
SAT-V-25(S) two stage payload capability to 100 nautical mile
orbit is almost 494,000 pounds

Four solid rocket boosters added around the first stage. 100 seconds of
burn time and total of 4.45 million pounds of thrust.

Yeah, that would seriously increase the lifting capacity of the Saturn V!

Probably should have gotten its own name, like Saturn X.

So, a similarly upgraded Saturn V would have had nearly twice the
payload to LEO as SLS Block 2.

I don't think this comparison is unfair. If SLS Block 2 can get
"advanced solid rocket boosters" that are only notional at this time,
why can't Saturn V get similar upgrades as well?

Given all the questions about using solid rockets for manned space flight
back then, probably zero chance of getting it man-rated by the 1970s.

May have had serious design issues even for unmanned flights.

True, but if we're fantasizing about a time line where Saturn wasn't
canceled, you could use a Saturn 1B (stock or upgraded) for crewed
launches of Apollo capsules. Actually, I rarely entertain such
fantasies these days and prefer to focus on emerging launch vehicles (we
live in exciting times in that regard).

My bigger point is that I believe that SLS Block 2 is as fantastical as
an upgraded Saturn V would have been. In the mid 1960s, NASA
s budget was already being cut. Apollo/Saturn was seen as extremely
expensive, so it was being funded only to continue the lunar program.
Development funding (of things like evolved Saturn V) was simply never
approved even though you can find dozens upon dozens of NASA studies on
the subject.

Today, we're finally getting to the point where it's becoming obvious
that at $3 billion a flight ($2 billion for an expendable SLS and $1
billion for a supposedly reusable Orion) that Artemis is simply not
going to be at all economically sustainable (when compared to
private/NASA partnerships like commercial cargo and commercial crew).

Furthermore, talk of Artemis creating a lunar base is an absolute
fantasy if you can't launch enough crew to them (on SLS/Orion) to keep
them staffed. At best, Artemis could launch a crew of four every nine
months. And my guess is that since NASA only allows six month stays on
ISS, a nine month stay on a lunar base would be "pushing it", especially
when you consider radiation exposure. So, I don't see SLS/Orion being
able to "permanently" staff a lunar base. It just doesn't have the
flight rate necessary to realistically do so.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.