For Questions That Don't Merit Their Own Thread

[JoeSchmuckatelli]

7 hours ago, SunlitZelkova said:

China’s Type 075 and Type 076 amphibious assault ships still have a long ways to go for being operational

China's maritime innovation looks at times like watching SpaceX.  They're trying lots of things.  Some will inevitably succeed, as they're also doing what SX does: throw money at the problem.

The USMC, on the other hand got a lot of things right a long time ago... but innovation in the US Amphibious capability spectrum basically died because of too many cooks.  USMC wanted a capable ship-to-shore fighting vehicle that could replace the Vietnam-era stuff we (currently) use that had modernized comms, weapons platform and was capable of keeping up with Abrams tanks.  Navy said they only wanted to drop us off over the horizon.  Enter the AAAV - which did none of that well.  (It had potential to be a good, amphibious, combat capable troop carrier... but trying to also make it hydroplane from OTH?  Nope.)  Recent experience in our 20+ year adventure introduced the concept that RU Anti-Armor weapons (and presumably CN) exported to everyone meant that Armor was on a down-tick in the perpetual arms race.  No one seems to be spending money in the US (yet) to figure this out - but the USMC, having dumped a LOT of weight in the last year (Armor, Arty, MPs, etc) looks to be trying to figure out what the future of American Amphibious Warfare might look like - however we have yet to see what tools / doctrine will emerge.

[wumpus]

3 hours ago, JoeSchmuckatelli said:

Tilt rotor aircraft are very difficult, from what I understand.*  Prior to fleeting them, they enjoyed a well deserved bad reputation for killing crews and in a not predictable manner.  People designated 'crew' and their extended families did not appreciate this and expressed themselves until the 'engineering difficulties were solved'... and now they are all over the place (in the USMC - the Navy gets theirs soon). 

However

"The MV-22 Osprey has a dismal mission capable rate hovering near 60 percent, according to data from the Marine Corps. Corps officials say that mission capable rate is an increase from the low 50 percent levels maintained throughout fiscal year 2018"  https://www.marinecorpstimes.com/news/your-marine-corps/2019/06/24/despite-massive-show-of-air-power-nearly-40-percent-of-marine-corps-mv-22-ospreys-are-not-mission-capable/

So as you can see - there is nothing to worry about and more nations should invest in the clearly capable technology! 

 

 

*This 'understanding based on client-side observations rather than manufacturing knowledge.  Given that client side users rarely donate to Senate campaigns quite as aggressively as Defense Manufacturers, Client - Side concerns are of no importance when deciding whether to fleet a given miltech 

Way back in the early 1990s I worked for a tiny startup (that didn't startup) that was building a drone with a tilt rotor.  Note that as it was the 1990s, "drone" meant nothing more than a glorified RC aircraft.  But this one was a joint project with Scaled Composites and was designed by Burt Rutan.  The company I worked for was called Freewing, and so named because they were building planes that allowed the wings to rotate freely to a constant angle to the wind.  Mr. Rutan figured out that this would make tilt rotors far easier as the wings would naturally maintain the right angle for lift, and simply placing a rotor between tail and fuselage/engine would force the fuselage (and thus propeller) to whatever angle you wanted.

Alas, it was built a little too early (between the two wars in Iraq) and had French backing (a real disaster for the politics at the time).

http://acversailles.free.fr/documentation/08~Documentation_Generale_M_Suire/Conception/Formules_speciales/Divers/Freewing-Aircraft.pdf    A collection of stuff printed about them.  I'd take the job titles at the start with a grain of salt: the first two I remember.  But the rest of the employees consisted of an American mechanic/assembler a French electrical engineer (a bit to green to have a straight out of school [me] EE under him), and a Chinese aero engineer (unforgettably named "Yu Hu").  The company could likely replace all but the mechanic/fabricator reasonably easily (maybe he's the "project engineer".  I can't see him showing up at DoD meetings as a "project manager").

[JoeSchmuckatelli]

5 hours ago, wumpus said:

that allowed the wings to rotate freely to a constant angle to the wind

I read an article about this a decade or so ago - presumably quite a bit of efficiency was anticipated. 

The problem I heard with Osprey and other TR designs was that everything was fine until it catastrophically wasn't.  (Note: this is different from the normal kind of plane or Helo problem where people can survive the failure - Osprey wanted to take people with it when it died) IIRC it took a bit of luck and inspiration to get around the problem.   

 - Osprey initially also used a fraught drive shaft design that both contributed to the problem and hid other problems that had to be solved before it became capable.  In other words, they fixed Osprey and it kept killing people.  Now apparently, it does not - but it remains maintenance intensive. 

 

Despite all of this - I remember being pretty excited about the potential at the time.  It finally entered service just after I left the Infantry - and I remember being disappointed that I never got to ride one 

The MC consoled me with a tank, however, so it all worked out! 

Edited July 18, 2021 by JoeSchmuckatelli

[JoeSchmuckatelli]

..... New Question..... 

With China and the US (RU too?) currently flying reusable, autonomous VTHL craft - what is the cost effectiveness of the spaceplane these days? 

 

SX is presumably cost effective reusing boosters - but every criticism of Shuttle begins with cost and the slow turn around.  Have these new designs solved those problems?  Is the reusable spaceplane more cost effective as a terminal delivery platform than what SX (and others) are doing now? 

 

 

[SunlitZelkova]

I don’t think cost effectiveness is being taken into account by the people who wanted it (Air Force and PLA). If they have a mission that needs to be done, no matter the cost it will be done, although where possible presumably cost cutting measures are taken.

However the very nature of the X-37 and Chinese space plane means they won’t cost as much as the Shuttle anyways. They are smaller, and their missions last longer, so versus the Shuttle which could not be up for more than 17 days and thus incurred an enormous cost in comparison to the return from each flight, the X-37B and the Chinese space plane will fly missions lasting hundreds of days and therefore the cost is pretty low in comparison to the return they get (experimenting with different stuff in space and being able to bring it back down and see how it did).

So the X-37B and Chinese small spaceplane are likely cost effective considering the return they get on them, even if the actual amount of money being spent is similar to the Shuttle.

As to a crewed orbital spaceplane like the ones China is working on, we will just have to wait and see. A thing to keep in mind with the Chinese ones though (Tengyun and so on) is that all of them have fully reusable boosters- either they are air launched TSTOs or they are VTHL with a fly back booster like the original Space Shuttle design. No throw away external tank, no water logged SRBs that need to be rebuilt. So the cost will likely be lower than the Shuttle even if they have a ridiculous looking refurbishment apparatus for the orbiter.

Edited July 19, 2021 by SunlitZelkova

[kerbiloid]

What's a spaceplane purpose at all?

1. To rotate crews at lowest possible accelerations (2..3 g), so to use the cheaper ordinary humans and weak nerds, rather than specially selected and trained supermen.

The capsules provide ~4 g on managed descent.
But they anyway suffer from ~20 g on ballistic descent and LES engaging.
So, still no ordinary men. At least a fighter pilot level. Subsupermen.

On the shuttles tehy were launching ordinary human (even a randomly selected teacheress, exactly to show that now everyone can into space), but the shuttles weren't equipped with any escape system at all, so it was just playing a roulette, not a purposed decision. 14 didn't win.
If the shuttle was equipped with an ejection cabin, or at least with escape boosters, the overloads would be anyway up to 20 on ballistic descent.
The human who can survive 20 on emergency descent, doesn't bother with 4 on regular descent.

So, anyway a fighter pilot is required when you have an escape option. 
(A real escape option, not the shuttle "separation modes" handwaving).
The regular civils will likely die or receive heavy traumas.

So, the only a never-crashing  shuttle can allow to use the next-door-humans in space.
But it's definitely not about the multistage chemical rockets.
It's about skylons, microwaved teslaships, or fusion-powered airspace liners, which are just "daily flying there and back again" instead of "taking an expedition to ISS". Please, wake me up when they appear outside of KSP.

So, currently the spaceplanes can't use regular humans and guarantee their life.

 

2. To deliver the cargo.

Most of cargos need no humans to be delivered.

In the old times they were manually servicing heavy sats delivered to LEO by shuttle, before releasing them.
Now it's probably looking weird. 

And a standalone heavy sat which indeed needs a post-launch servicing, it's easier to equip with a docking port for a capsule ship.
Anyway no such sats to the date.

Station modules  can be self-delivered, like the Mir ones, just have a heavy rocket to equip them with a tug or use a built-in tug.
They can dock and re-dock automatically or remotely.
The only case when they need a human, is the CBM berthing port, but it's anyway operated from inside the station.

Also the spaceplanes can deliver something only to LEO, because of fragile wings and tiles. So, you hardly can use them to service a high-orbit combat platform.

So, no need in spaceplanes to deliver a cargo.

 

3. To return the cargo.

No cargo to be returned from space needs tonnes of capacity to the date.

Even the crystal production can reach up to several hundred kilograms per half-Mir orbital station (from plans).

No orbital craft needs to be landed and repaired, It's eiher cheap and bad, or de facto stays intact for a decade and longer.

Orbital labs are either stations, or small and fitting a capsule.

The derelict sat reactors are unlikely a proper cargo for a spaceplane.

So, the only cargos to be returned by a spaceplane are:
1) Secret sats, like the Shuttle was purposed for. Never happened even to Shuttles. Just once they returned one, just for "look, we did it!". It's either too reliable or too cheap to need a rotation for servicing.
Anyway, pure military.
2) Secret military mini-labs to be returned exactly into a barbed-wired workshop (a barbershop?). Pure military.
3) A nuke or a blaster. Still no civil nukes or blasters.
4) A lost PBV or a derelict lasersat. Still miitary.

4. To perform a crosswind maneuver, including but not limited with landing on a dedicated airbase.

No need for a civil flight, as it can just wait for several orbits to land.

Is actual only for:

1) Short-term orbit/suborbital military craft like a recon or an interceptor, as it can be launched to the orbit of random inclination, and may have the orbital lifetime of hours.
So, to land on a military base at 1 000 km aside from it trajectory it needs wings to S-maneuver sideways.

2) A winged warhead re-entry vehicle. To spread them aside from an ICBM or orbital platform trajectory, or to re-adjust the target coordinates in flight (say, to chase an aircraft carrier, cowardly sneaking here and there from the planned GZ, instead of bravely standing there, like a true man-o-war should).

3) A winged platform spreading warheads on its own.

So, no civil purpose until the skylons, teslaships, etc..

 

5. To bring back the second stage engines.

The shuttle did it.

Is relevant when you anyway have to launch humans every time. But you don't.
Otherwise it's a launching of 12 t ballast (the crew cabin).

 

6. To return reusable service modules of capsule ships, berthing them to the station, and later returning home by a spaceplane.

I.e.
Launch a capsule ship to ISS, dock it with nose.
Grab the service module by arm, detach it from the capsule, berth to a radial CBM port (it should be equipped with a passive CBM ring too, of course).
Undock the ship capsule and deorbit it with a solid-fuel deorbiting motor.
Repeat with the next capsule ship.
Next time launch a spaceplane, grab both berthed modules from the station and put them into cargo bay, return the spaceplane.
Reuse the service modules.

Currently not even in plans.

***

So, there is no relevant purpose for a spaceplane except the pure military ones.

Until skylons, etc.

So, there is not much to be about the economic efficiency there.

Edited July 19, 2021 by kerbiloid

[JoeSchmuckatelli]

51 minutes ago, kerbiloid said:

So, there is not much to be about the economic efficiency there.

"Freak out the neighbors" 

Roger that.  Space planes can still do that one critical role.

[editor99]

Q: How does a orion drive not blow itself up, what about the explosion caused by the bomb?

Or shrapnels and/or shockwaves from the explosion?

(Shockwaves apply only when launch)

Edited July 19, 2021 by editor99

[kerbiloid]

There is no shockwave in vacuum, so almost all nuke energy gets released as X-rays and partially neutrons.

The neutrons get reflected by the beryllium oxide filler between the nuke and the tungsten membrane, back to the nuke.

The X-rays get absorbed in same filler and turn into plasma.

The beryllium plasma partially re-emits the energy omnidirectionally as infrared photons.

Those of the IR photons which are directed to the ship, gets absorbed by the tungsten membrane, turning it into plasma.

The beryllium plasma pushes the tungsten plasma towards the ship.

The beam of the tungsten plasma flies towards the ship, expanding radially.

 

The ship spreads oil on the pusher plate surface between the blasts.

The infrared radiation of the approaching tungsten and the nuke cloud boild the droplets of the oil, turning it into oil cloud, and then into relatively cold post-oil plasma.

The tungsten plasma hits the post-oil plasma cloud and this softens its hit.

 

The cloud of plasma softly hits the pusher plate.

The water coolant gets pumped through the plate internal structure on hit by the force of the hit.

The evaporated water coolant gets exhausted as steam.

 

The first tier of the piston dampener softens the plate acceleration from 10 000 g to 100 g.
The second tier of the piston dampener softens the plate acceleration from 100 g to 1 g.

The cycle repeats.

***

The launch is out of the project scope, but later projects used auxilliary rockets to get from ground to thin air before starting nuking, and the same to land one of several Orions on Mars and leave it there as a base.

Most of Orions "were" permanently orbital.

Edited July 19, 2021 by kerbiloid

[Admiral Fluffy]

What is the LF+OX consupion ratio?

Like how much Oxodizer for one unit of Liquid Fuel?

[JoeSchmuckatelli]

42 minutes ago, Admiral Fluffy said:

What is the LF+OX consupion ratio?

Like how much Oxodizer for one unit of Liquid Fuel?

Not a chemist, but I suspect it is determined by the chemistry of the LF and how it oxidizes

 

Got a particular LF in mind? 

Edited July 19, 2021 by JoeSchmuckatelli

[Admiral Fluffy]

2 hours ago, JoeSchmuckatelli said:

Not a chemist, but I suspect it is determined by the chemistry of the LF and how it oxidizes

 

Got a particular LF in mind? 

Umm, the KSP LF.

[StrandedonEarth]

58 minutes ago, Admiral Fluffy said:

What is the LF+OX consupion ratio?

Like how much Oxodizer for one unit of Liquid Fuel?

11:9 IIRC. 

[OrdinaryKerman]

2 hours ago, Admiral Fluffy said:

What is the LF+OX consupion ratio?

Like how much Oxodizer for one unit of Liquid Fuel?

Kerbal LF+Ox? Then normal engine consumption ratio is 11 Ox : 9 LF.

[JoeSchmuckatelli]

14 minutes ago, Admiral Fluffy said:

Umm, the KSP LF.

Grin - this is the general science part of the forums, so it's good to check.  As noted, far more educated members than I have the answer!

[JoeSchmuckatelli]

How much actual rotation of a galaxy's stars can Hubble resolve?  

 

 

(*Edit: star's travel around it's galactic center, not stellar rotation itself)

FWIW - googling gets me a bunch of old images, simulated images and pictures with graphs. I'd actually like to see date stamped images so I can see if I can see what the articles describe - - or learn if the distance is so great that we can't tell the motion optically and must infer it from other data. 

 

Edit 2: this is cool Spacecraft Flies Through Dusty Tail of Exploded Comet in Unique Chance Encounter (msn.com)

Oddly they got magnetic readings from the remnants

 

Edited July 20, 2021 by JoeSchmuckatelli

[kerbiloid]

After the Project Horizon pdf links had been removed in wiki (I wrote about this earlier), also the Smyth Report pdf links are 404ed.

Check and backup your Project Orion links, as who knows what's going to happen to them.

Looks like somebody has played the retro-futuristic Fallout, and old ideas began shining in new colors. 

Otherwise why all this Orion hype, lol?

Edited July 21, 2021 by kerbiloid

[K^2]

On 7/20/2021 at 9:33 AM, JoeSchmuckatelli said:

How much actual rotation of a galaxy's stars can Hubble resolve? 

Depends on a lot of factors. Our best tool for measuring how fast stars are moving is still going to be red shift. That means that you have to be able to detect spectral lines. If you are looking at a star in our own galaxy, you can resolve individual star with Hubble and then you just have the spectrum which you can use to measure the movement speed precisely enough that you can tell what kind of planets are orbiting the stars by the wobble in speed. The precision of measurement can be as good as a few m/s.

When looking at stars in another galaxy, you aren't going to be able to resolve individual stars, but so long as there are a few particularly bright stars in a "pixel" of the image to give you clean spectral lines, it's good enough. So for "nearby" galaxies at least, so long as their plane of rotation causes stars to move towards and away from us, we can do very good measurements on velocity distribution around the disk. These are precise enough for us to tell how much dark matter there is in the galaxy, for example, and we've been able to corroborate it with gravitational lensing in some cases.

There is also obviously a limit to this. As you are looking further out, the stars are going to all blur together, and at some point, you're lucky if you can get an average speed for the galaxy. There is a way to put some theoretical limits on this using the size of the Hubble's main mirror, but I have a feeling that the instruments capable of spectral analysis aren't going to be able to have the same resolving power as the main cameras, so I don't know if that would be a useful estimate. Orientation of the galaxy will also matter. If we are looking more along axis of rotation, there is less red shift for us to measure. All of this combined, I don't really know at what distance the above methods are actually effective using Hubble.

[JoeSchmuckatelli]

Thanks!  I wasn't aware of how they did it, but I have seen some spectacular galaxy photos from Hubble - and it did not look like it was easy to pick out stars and look at rotation speed 

[Jacke]

8 hours ago, K^2 said:

When looking at stars in another galaxy, you aren't going to be able to resolve individual stars....

Some of the stars in the nearer galaxies can be just resolved.

During World War 2, due to Los Angeles being blacked out, Walter Baade used the 100in Hooker Telescope on Mount Wilson to resolve stars in the Andromeda Galaxy and do so well enough to measure the periods of the Cephid variable stars therein.  It helped establish the existance of two broad populations of stars and that their Cephids had different luminosity-period relationships.  That about doubled the distance calculations made earlier by Edwin Hubble, including that to the Andromeda Galaxy.

https://en.wikipedia.org/wiki/Walter_Baade

[JoeSchmuckatelli]

13 hours ago, Jacke said:

Walter Baade used the 100in Hooker Telescope on Mount Wilson

That was a cool read - thanks! 

[kerbiloid]

https://www.sciencemag.org/news/2021/06/soil-without-life-discovered-first-time-earth

Bye, Mars, Europa, and Enceladus life.

[SOXBLOX]

Did anyone here see or hear that fireball/bolide/whatever over Texas just now? It made my whole house shake when it blew up. 

[kerbiloid]

Yesterday it was in Norway.

Spoiler

 

The Earth is under attack!

[Jestersage]

Question: Are there any solar panel systems that is re-foldable? Or are they all technically refoldable, just bad idea to do so?

To my recollection, the only refoldable solar panels are those on Zarya... and may be one or 2 of the Salyut.

Had Soyuz ever fold its solar panels? What about any satellates/solar powered probes?

Edited July 26, 2021 by Jestersage