Skyler4856

For Questions That Don't Merit Their Own Thread

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What mods are you running? I wouldn't rely on stock aerodynamics to tell me much of anything about real world vehicle performance and for the range of flight regimes experienced by the Shuttle, I don't know if a full set of realism mods would tell you much either.

However I don't know nearly enough about this to tell you why the Shuttle did have a big tail.

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Posted (edited)

4 hours ago, TheDestroyer111 said:

Why did the space shuttle have such a huge, high vertical stabilizer on top of it? Aerodynamics Testing In KSP™™™ proves that the high torque makes spin recovery very hard, and just touching the rudder dangerous.

I think the rudder layout of the stock Dynawing would be much more reasonable for the space shuttle.

The vertical stabilizer is also the non-deflecting part of the tail fin, which prevents the plane from side slipping. The shorter the plane, the larger the vertical stabilizer has to be to keep the plane stable (and the Space Shuttle isn't very long, compare it for example to a Boeing 747SP).

The part, you are struggling with, is the rudder, which gives yaw control. One part might be that in reality you have much more delicate control as to how much you want to deflect them. Maybe it also needed extra large control surfaces for control in the thinner parts of the atmosphere (the other control surfaces on the shuttle aren't small either).

In case of the shuttle, the large size of the rudder (the moving part of the vertical stabilizer) might also have to do with the fact, that the shuttle's rudder was split in two parts allowing it to deflect to both sides simultaneously to act as a speed brake (this is actually modelled in KSP, if you deploy its control surface).

As to why the stock Dynawing has this peculiar arrangement with the vertical stabilizers at the wing tips, I can only speculate as a player having built my own shuttle replica in KSP: If you use the Space Shuttles rudder during launch to control yaw, it generates an enormous amount of roll, as the center of mass is sitting very far away inside the external tank. On the other hand, on the stock Dynawing, the rudders a sitting much closer to the center of mass and thereby generate much less roll during launch, and none during the glide home, making it much simpler to control as using yaw has no negative side effect on roll.

Edited by Tullius
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Posted (edited)

I wasn't able to find much information on how the aerodynamics of the orbiter are used during ascent but during descent, they don't even use the rudder until they've slowed to approximately mach 1: https://www.nasa.gov/audience/forstudents/9-12/features/F_Aeronautics_of_Space_Shuttle.html I couldn't find the original document that said what controls they used at what part of the flight envelope but yaw control is the last one they switch to aerodynamic control. The first part of entry is at something like mach 25 but they're going too fast and the atmosphere is too thin for the aerodynamics to work so they use RCS. Although the body flap I think controls the AOA. It's also worth noting that the orbiter is almost entirely flown by computer even though the RCS/control surfaces are tied right into the stick.

ETA: (of course as soon as I post, I think of something else) It's entirely possible that with the fly-by-wire, they compensate for roll while using the rudder with the elevons automatically. This is something that KSP is not very good at.

Edited by Racescort666
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5 hours ago, TheDestroyer111 said:

Aerodynamics Testing In KSP

As the Mythbusters used to say - "well, there's your problem".  You're trying to use KSP to illustrate a problem it's not equipped to properly simulate.

 

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Sorry for not clarifying it, I meant it creates high ROLL torque :(

 

Just why not place the vertical stabilisers on the wingtips like the Dynawing? This way you could give the stabilisers the same size but less roll torque.

 

@Racescort666 yeah lol fly-by-wire can fly basically anything that has enough lift or thrust, but even fly-by-wire can't recover anything from a spin, and I thought that an aircraft that can't recover from a spin is like *almost* illegal to fly :P

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On 04/08/2017 at 4:20 PM, TheDestroyer111 said:

Sorry for not clarifying it, I meant it creates high ROLL torque :(

 

Just why not place the vertical stabilisers on the wingtips like the Dynawing? This way you could give the stabilisers the same size but less roll torque.

 

@Racescort666 yeah lol fly-by-wire can fly basically anything that has enough lift or thrust, but even fly-by-wire can't recover anything from a spin, and I thought that an aircraft that can't recover from a spin is like *almost* illegal to fly :P

Because that would load the wings more, making them heavier. It would also potentially increase drag and reduce the efficiency of the control surfaces, as the wingtips are a particularly sensitive part of the aircraft due to the vortices they generate.

In general, the roll torque caused by the off-centre vertical stabiliser can easily be offset by using the ailerons. This solution works well enough that it's not worth increasing the wing loading by putting the vertical stabilisers on the wingtips.

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My question: 

Why is putting solar panels on roads more effective than putting them by the roadside, where they won't have the weight of a car going over them? Surely even having them suspended above the road would make them cheaper?

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1 hour ago, Skylon said:

My question: 

Why is putting solar panels on roads more effective than putting them by the roadside, where they won't have the weight of a car going over them? Surely even having them suspended above the road would make them cheaper?

In short, they're not more effective. It's more a public perception issue, most people don't like looking at giant solar farms by the side of the road so are resistant to having them built, where as they're less resistant to having them in the road.

Edited by Steel
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Here's a fun scenario I thought up. Let's say I go back in time 65 million years and a few days, swat the Chixulub impactor out of the way, and in it's place I put a large tank of antimatter with an amount of antimatter with a mass-energy equal to one half of the impact energy of the Chixulub impact (surrounding matter should account for the other half, I think). If the antimatter all stays in the tank until it hits the seafloor in the Yucutan peninsula, how would the resulting explosion be different from the impact that took place in real life? Would the fireball, tsunami, EMP, earthquakes etc etc be the same size and strength or not?

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13 hours ago, ChrisSpace said:

Here's a fun scenario I thought up. Let's say I go back in time 65 million years and a few days, swat the Chixulub impactor out of the way, and in it's place I put a large tank of antimatter with an amount of antimatter with a mass-energy equal to one half of the impact energy of the Chixulub impact (surrounding matter should account for the other half, I think). If the antimatter all stays in the tank until it hits the seafloor in the Yucutan peninsula, how would the resulting explosion be different from the impact that took place in real life? Would the fireball, tsunami, EMP, earthquakes etc etc be the same size and strength or not?

It shouldn't be all that different, although it would likely be harder for later paleontologists/geologists to figure things out if it doesn't have a layer of iridium on the K/T boundry.  The geological effects would be different, unless you somehow shaped the charge of the antimatter to match the energy dispersal of the meteor.  I can't imagine that slightly different geological effects (due spreading the outward pressure more equally instead of biased downwards) would be terribly significant.

Probably the biggest difference would be more energy would radiate away from the Earth, you might need a slightly larger amount of anti-matter.

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One thing I've seen as a reason not to use NTRs is potential public issues with putting nuclear reactors at risk of launch failure.  How much worse for the environment than Hypergolics (already present in many, if not all, rockets), would it be?  How would the effects differ between say, a launch off the Cape and debris falling into the sea, as opposed to Baikonur?

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38 minutes ago, 1101 said:

One thing I've seen as a reason not to use NTRs is potential public issues with putting nuclear reactors at risk of launch failure.  How much worse for the environment than Hypergolics (already present in many, if not all, rockets), would it be?  How would the effects differ between say, a launch off the Cape and debris falling into the sea, as opposed to Baikonur?

Luckly, the public doesn't know what hypergolics are, so they have no problem with them. If knowledge of what they actually are was a common as "knowledge" (I use the term loosely) about nuclear reactors, there probably wouldn't have been silos full of hypergolic nuclear missiles all over the US a few decades ago.

Having said that, the effects of a nuclear accident will last considerably longer (potentially hundreds of years) as opposed to a hypergolic accident (maybe a few days). It also depends hugely on the size of the reactor in question, obviously a probe sized reactor like the ones we have currently launched are not especially dangerous even if they leaked, as long as it was somewhere remote and not in mid-air. The worst case scenario with any nuclear reactor is that it bursts and breaks up in a launch accident and spreads radioactive material over a wide area.

The environmental damage to humans would be much less over the sea near the Cape rather than at Baikonur, but you'd still end up evacuating all the beaches for a hundred miles in case radioactive material started to wash up on the shore. It would only take one bad accident to end the whole thing indefinitely over "safety concerns".

 

The problem with public perception is that it very rarely has any correlation with the facts about whatever is in question. You can design the safest nuclear reactor possible, but one ill-informed celebrity shouting "CHERNOBYL!!!?!?!11" on social media will scare enough people to make it a PR nightmare (or one stupid clickbait article in a dodgy tabloid, along the lines of "NASA rockets have NUCLEAR BOMB ONBOARD, even a small accident could be THE END OF DAYS"). It's the same sort of situation as with global warming, you can't persuade people with facts if the facts don't fit into their personal world views. There are actually studies (I'll try to find a link later) that conclude that if you try to persuade a non-believer that climate change does exist by showing them facts, you're actually more likely to cement their denial than change their mind. The TL;DR from all this is that the public in general don't care how safe something actually is, just how safe they think it probably is.

Edited by Steel
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The effects of radioactivity is often underestimated due to bad information.

In 1978 a nuclear (reactor core containing enriched uranium) powered satellite crashed over Canada, distributing its debris over more than 100.000 square miles kilometers. Only a very few parts were found, still some had enough radioactivity to kill a person. Imagine what would happen if it crashed into populated areas. I do not know if newer satellites of the likes of these are "better" but i doubt it.

Together with the three mile island incident It changed the public perception of nuclear power in northern America in the late 70s.

 

p.s.: don't pick up things that look scorched, lying on the ground in northern Canada ;-)

Edited by Green Baron
I should stick to real units :-)
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5 hours ago, Steel said:

Luckly, the public doesn't know what hypergolics are, so they have no problem with them. If knowledge of what they actually are was a common as "knowledge" (I use the term loosely) about nuclear reactors, there probably wouldn't have been silos full of hypergolic nuclear missiles all over the US a few decades ago.

The amount of hypergolics used in modern rockets are pretty small.  On the other hand liquid oxygen has a tendency to turn everything it touches into an explosive (charcoal makes a high explosive).  If you tried to launch a Proton out of KSC or Vandenburg I would expect a bit of an outcry, and I have trouble believing that the Russians are still launching those things.

Of course, the usual "public panic" about toxic substances always ignores the dose.  Ignore the dose and any toxicity report is mindless babel.

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Hid a few posts that digressed off-topic.  Nothing more to see here.  Move along, citizens.  :)

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Yes

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