For Questions That Don't Merit Their Own Thread

[kerbiloid]

As any rocket fuel containing oxidizer consists mostly of oxygen and of nitrogen or a halogen binding that oxygen, it anyway can't be much denser than water. It can sink, but nothing more.

[ARS]

Why it's very rare to find a missile-launching submarine with forward silo placement (the VLS is placed in front of the sail instead of behind it)? So far what I know is Typhoon-class submarine with forward-mounted VLS , while most other submarine uses rear-mounted VLS. What's the advantage and disadvantage of forward mount VLS? And why it's rarely used?

[DDE]

1 hour ago, ARS said:

Why it's very rare to find a missile-launching submarine with forward silo placement (the VLS is placed in front of the sail instead of behind it)? So far what I know is Typhoon-class submarine with forward-mounted VLS , while most other submarine uses rear-mounted VLS. What's the advantage and disadvantage of forward mount VLS? And why it's rarely used?

Educated speculation would be the impact of the sail itself on maneuvering, since it's an unwanted additional fin. The sail, specially the thin and tall sail favored by NATO submarine designs, is known to induce roll and instability when turning at high speeds. Similar disbalancing is known to affect surface ships as well - the Nelsons were tricky to conn.

Spoiler

A competing radical solution is to put your money where your mouth is. Russian USVs already have a massive tailfin-antenna.

http://www.hisutton.com/images/FutureSub-2040-Cutaway.jpg

The problem, of course, is that the sail traditionally housed the periscopes, hence all command facilities were inside and underneath the sail.

[magnemoe]

8 minutes ago, DDE said:

Educated speculation would be the impact of the sail itself on maneuvering, since it's an unwanted additional fin. The sail, specially the thin and tall sail favored by NATO submarine designs, is known to induce roll and instability when turning at high speeds. Similar disbalancing is known to affect surface ships as well - the Nelsons were tricky to conn.

  Hide contents

A competing radical solution is to put your money where your mouth is. Russian USVs already have a massive tailfin-antenna.

http://www.hisutton.com/images/FutureSub-2040-Cutaway.jpg

The problem, of course, is that the sail traditionally housed the periscopes, hence all command facilities were inside and underneath the sail.

For an surface ship like a battleship I don't think the tower would have much of an effect, now I expect an carrier or cruise ship with their huge superstructure would behave different in strong wind but probably other factors with Nelsons, probably hull form or rudder placement. 

I assume for an future sub you would not watch trough the periscope anyway but on an screen showing that it see. Here it looks like crew are located rear anyway. 
Now I'm curious about the very lightweight torpedoes, an obvious use would be anti torpedoes as this does not require much range or large warhead but the second type is assigned to this. 

[StrandedonEarth]

Will Hubble be able to get a useful image of  JWST at L2?

I’m thinking not…

Edited December 26, 2021 by StrandedonEarth

[DDE]

1 hour ago, magnemoe said:

For an surface ship like a battleship I don't think the tower would have much of an effect, now I expect an carrier or cruise ship with their huge superstructure would behave different in strong wind but probably other factors with Nelsons, probably hull form or rudder placement. 

Except that everyone at the time blamed the "Queen Anne's mansion" acting as a sail.

[JoeSchmuckatelli]

Telescope Q: Barlow adapter?

With a short (400mm) focal length scope (100mm aperture), if I wanted a Barlow adapter would it be better to get a 1.5 x or 2x? 

 

(Current 17mm and 10mm lenses offer 40x or 24x magnification).

 

also - anyone know whether filters can be used with a Barlow?  (Just ordered a 4 filter set b/c the MOOON is BRIGHT)

Edited December 26, 2021 by JoeSchmuckatelli

[StrandedonEarth]

1 hour ago, JoeSchmuckatelli said:

the MOOON is BRIGHT)

“M-O-O-N, that spells Moon. “ - Tom Cullen

[JoeSchmuckatelli]

22 minutes ago, StrandedonEarth said:

“M-O-O-N, that spells Moon. “ - Tom Cullen

One of my favorite characters from my youth! 

[SOXBLOX]

13 hours ago, JoeSchmuckatelli said:

Telescope Q: Barlow adapter?

With a short (400mm) focal length scope (100mm aperture), if I wanted a Barlow adapter would it be better to get a 1.5 x or 2x? 

 

(Current 17mm and 10mm lenses offer 40x or 24x magnification).

 

also - anyone know whether filters can be used with a Barlow?  (Just ordered a 4 filter set b/c the MOOON is BRIGHT)

Either size works. What you get really depends on two things, the eyepiece barrel size, and the actual aperture of your scope. If your aperture is fairly large, a 2x should be just fine. If it's on the small side, maybe just go with the 1.5x. Eyepiece barrel diameter matters because that determines how many choices you have. If it's a non-standard size (usually anything less than 1.25'') you won't have lots of choices. If it is 1.25'' or 2'', you're fine.

Above all, the main factor is quality! Barlow lenses have a large effect, and if they have a defect, it really stands out.

The filters should work fine. I can't imagine them causing optical problems.

Anyway, happy observing!

[JoeSchmuckatelli]

1 hour ago, SOXBLOX said:

Either size works. What you get really depends on two things, the eyepiece barrel size, and the actual aperture of your scope. If your aperture is fairly large, a 2x should be just fine. If it's on the small side, maybe just go with the 1.5x. Eyepiece barrel diameter matters because that determines how many choices you have. If it's a non-standard size (usually anything less than 1.25'') you won't have lots of choices. If it is 1.25'' or 2'', you're fine.

Above all, the main factor is quality! Barlow lenses have a large effect, and if they have a defect, it really stands out.

The filters should work fine. I can't imagine them causing optical problems.

Anyway, happy observing!

it's a 1.25.  Aperture is 100mm (4 inches) so... I'll go with the 1.5x.  Thanks for the tips!

Any brands you recommend - or ones to stay away from?

...

Oh - follow up: the Jovian moons had noticeably changed positions.  Daughter thought that was really cool.  

FYI - Jupiter is about to leave the nighttime skies for a bit; Saturn, which we saw last night is already down with the sunset.  Super glad to have had this opportunity with her.

Sad thing is that my part of the country is known to be 'gray' from now till spring.  We've fought clouds for a couple of nights, and still seen cool stuff.  Hopefully we get a few clear nights over the next few months!

 

S/F ALL!

[kerbiloid]

@DDE, please, what's the exact translation into English of the famous "роторный магнитоплазменный двигатель" on Zeus/Nucleon?

Which exactly design from Atomic Rockets it matches?

[DDE]

1 hour ago, kerbiloid said:

@DDE, please, what's the exact translation into English of the famous "роторный магнитоплазменный двигатель" on Zeus/Nucleon?

Which exactly design from Atomic Rockets it matches?

I feel like I'm famous.

If I'm reading this patent correctly, we're looking at a mechanically cranked electric thruster *obligatory Gatling gun reference* using either a flywheel or a reactor turbine. That's a rather brilliant way to approach the problem, I must say. Pretty sure it fits into the "applied field magnetoplasmadynamic" category, just using a novel source of inducing a magnetic field.

[kerbiloid]

Thank you!

I just tried to get through the known youtube channel of its fan, trying to extract dusticles of common sense out of the river of enthusiasm, and the MAKS'21 toyship uses this and of course mentioned many times.

So, as you are probably more familiar with both the subject and the language, I guessed that maybe you know what part of AR does he mean.

Probably this one, as I can see.

[K^2]

33 minutes ago, DDE said:

If I'm reading this patent correctly, we're looking at a mechanically cranked electric thruster *obligatory Gatling gun reference* using either a flywheel or a reactor turbine. That's a rather brilliant way to approach the problem, I must say. Pretty sure it fits into the "applied field magnetoplasmadynamic" category, just using a novel source of inducing a magnetic field.

I'm now dumber for having read this patent. The author does not understand how EDF works, how nuclear reactor works, lacks either understanding or patience for working out the thermodynamics of this mess, and seems to only have some hands-on knowledge of turbine construction. Based on symbols used, my guess would be someone whose profession is in either service or construction of diesel turbines. The only good reason to use propellant as heat exchanger in a nuclear rocket is if you are going to expel hot propellant. Having it run through turbines and a cooling contour is absurd. And the electromagnetic portion, as described, does absolutely nothing but waste energy and thrust. This would be obvious if author attempted an estimate of the thrust, but, of course, no computations of any sort are evident in the patent. Since the working gas is cooled before getting expelled, the only thrust the unit produces is from whatever residual pressure is present in the loop which isn't going to be much. There are other parts that are just stupid. Magnetic field is shown as a loop in empty space inside the nozzle, so the author clearly never heard of Stokes' Theorem.  Working fluid goes through an evaporator before heading to the compressor for some arcane reason. There is current shown flowing from anode to a cathode... The whole thing's a disaster.

[kerbiloid]

To get more specific.

(Just in case, this is not the mentioned youtuber.)

https://translate.google.com/website?tl=en&nui=1&u=https://yuripasholok.livejournal.com/13526969.html

Spoiler

https://peremogi-livejournal-com.translate.goog/56866551.html?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=ru

Btw, in the right-lower corner of the videopresentation schreenshot.
The Clipper ship was cancelled in 2009.

Spoiler

 

Edited December 27, 2021 by kerbiloid

[SOXBLOX]

7 hours ago, JoeSchmuckatelli said:

it's a 1.25.  Aperture is 100mm (4 inches) so... I'll go with the 1.5x.  Thanks for the tips!

Any brands you recommend - or ones to stay away from?

...

Oh - follow up: the Jovian moons had noticeably changed positions.  Daughter thought that was really cool.  

FYI - Jupiter is about to leave the nighttime skies for a bit; Saturn, which we saw last night is already down with the sunset.  Super glad to have had this opportunity with her.

Sad thing is that my part of the country is known to be 'gray' from now till spring.  We've fought clouds for a couple of nights, and still seen cool stuff.  Hopefully we get a few clear nights over the next few months!

 

S/F ALL!

Celestron, Meade, and Orion are all good brands. Vixen is good, too, but I *think* they might have some sort of compatibility issue.

I understand how you feel about the clouds! Hopefully you get some good cool fronts to knock them out for a little while. 

[DDE]

Why did the bomber tail gun die? Remote control eliminated much of the complexity of having a second crew compartment, and the later tail gun turrets had comparable firepower and fire control to light CIWS while facing far shoddier missiles coming in at reduced relative speed.

[kerbiloid]

Probably no fighter wants to hang on the bomber's tail when it can just launch several rockets.

[SOXBLOX]

2 hours ago, DDE said:

Why did the bomber tail gun die? Remote control eliminated much of the complexity of having a second crew compartment, and the later tail gun turrets had comparable firepower and fire control to light CIWS while facing far shoddier missiles coming in at reduced relative speed.

Because when strategic bombers were used in the Cold War, it was for nukes. And when you nuke a city, it only shoots at you before it's been nuked. After, there's no problem. So a gun on the tail was probably not useful.

Actually, I'm joking. This article says they were already fairly ineffective by the end of WWII. Then, in Vietnam, B-52s scored just two kills in the entire war. As for using it as CIWS, I think we just didn't have the tech in the 50s-60s to build something like that which could fit in a bomber.

[Jacke]

11 hours ago, DDE said:

Why did the bomber tail gun die? Remote control eliminated much of the complexity of having a second crew compartment, and the later tail gun turrets had comparable firepower and fire control to light CIWS while facing far shoddier missiles coming in at reduced relative speed.

Also, in the 1950's, Continuously Computed Collision Course was possible with analog computers, so interceptors no longer had to tail-chase a bomber, but could be vectored ahead of it for a CCCC.

Edited December 28, 2021 by Jacke

[kerbiloid]

The gunners were dismissed, but were their positions in the salary sheet?..

[magnemoe]

5 minutes ago, Jacke said:

Also, in the 1950's, Continuously Computer Collision Course was possible with analog computers, so interceptors no longer had to tail-chase a bomber, but could be vectored ahead of it for a CCCC.

An excellent point however side or frontal assault was done, but the side ones was much harder even on bombers. 
This has gotten an upgrade in the last decade by letting the firing computer fly the plane for shooting, this let you do stuff like shooting trough an window making strafing with the gun pretty effective and much cheaper than an missile downside is that you need to get low. 

Still faster planes and missiles was the reason why they stopped using it, Various decoys to fool missiles was more effective use of the weight. 
Lasers will probably change this in the future. 

[Terwin]

On 12/24/2021 at 4:31 AM, Hyperspace Industries said:

I'm thinking of making a model rocket motor that uses the reaction of baking soda and vinegar and then pushes the expanding foam through a nozzle to make at least a bit of thrust. I can't find the rate at which the foam expands anywhere on the internet (all I get is cork gun rockets) I'm looking for a rocket engine with not too much thrust (very low thrust actually) and constant exhaust instead of a cork gun rocket's single burst. Also it can't use combustion because that is literally illegal here.

Are there any such reasonably easy to build model rocket engines.

Also: what rate does baking soda and vinegar expand at, and could my model rocket idea work.

You might have greater success with a water rocket.

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

That gives you non-instant thrust with no worries about reaction rates, hazardous materials, or fire-codes.

 It is also very easy to come-by disposable launch vehicles(aka soda-bottles) if you build a launch stand for them.

[Jacke]

6 hours ago, Jacke said:

...Continuously Computed Collision Course....

Would help if I spelled that correctly, as I've corrected now.  What it does is use radar tracking info on the target, speed and direction, and known speed of the interceptor to aim the interceptor ahead of the target to allow the quickest encounter, getting within effective range of the interceptor's weapons.