Project Bases to Land Planet Hopper Class star ships

[TCR_500]

I'm using imperial units for the bases. It's what I know, and I know how to convert them.

Now I need to do the Mars base. Although I'll need to create a texture so it won't look like a runway, but instead, it'll look like the martian surface.

 

[garyw]

Wouldn't you want the runway to be visible? If it looks like the Martian surface you are going to miss.......

Screenshots?!

 

[Nerull]

And I've already known that 100 m is 328.08 feet.

Do you really think lying like this makes you look smart? I can assure you it has the opposite effect.

 

[Urwumpe]

And do you know that there is an international law, supported by the US government, to use SI units in spaceflight, especially in deep space (like Mars and Moon are).

 

[ex-orbinaut]

Runway tested last night...

Wow! This thread has grown. Cannot vote. There is no need for runways, as far as I can see (now)... Read on a bit.

Okay. Runways on the moon tested. Installed a 09-27 runway at Brighton Beach and tried it late last night. Made two playback videos, one of a hover landing & one of a runway landing, starting from the exact same point 500 km out, for comparison control. The verdict; apart from it being pretty :speakcool:, there is little practical point in it, now that my acquisition of a hover over a given point is better than it was (see note at bottom if you're interested in what I am doing). Gave the idea the benefit of the doubt, for some fun, but there is only a little saving in fuel, as rightly informed by Urwumpe, just as long as you can do the hover landing quickly and don't overshoot the mark.

But discovered this shortcoming with Orbiter. The brakes in the simulation work just as well on the Moon as they do on Earth. The effect of braking on reduced tire displacement in low gravity DOES NOT seem to be simulated, presumably because you are not expected to land runway fashion on atmosphere-less bodies(?). So, note for TCR 500, if you want to persist in making runways on the Moon, you are going to have to implement a function in your code that gets the planet's mass and modifies (reduces) the braking coefficient accordingly. In reality, in a low gravity environment under braking conditions, a certain amount of "tire skipping" is going to occur, too, further reducing brake effectiveness. I would not bother, really. Use the pads...

NOTE: How I improved my Moon approaches. Used a very simple bit of time / distance vs. acceleration math which works pretty well. Divide the velocity by 85% of the max retro thruster acceleration (gives you the time in seconds it is going to take to slow down). Then multiply that by half your velocity. It gives you the distance in meters at which you should light the retros (ship pointing prograde), in order to stop over the target.

An example: (1700 / (4 * 0.85)) * (1700 * 0.5) = 425000 meters (light the retros at 425 km from the base).

Why the 85% and not 100%? I use part of the retro thrust to generally arrest the rate of descent, by incrementally pitching the nose down as velocity bleeds off (I don't use the hovers untill the end). The average horizontal retro thrust component over the trajectory works out at about 85% of the total available. Got more on this through testing and recording the pitch angles, but this post is already too long, so I skip that. And that 85% is applicable only for the Moon. It will vary for other bodies, & be impossible for really massive ones.

Pick holes in it, if you like, but it does work and is better than "using the force", as I more or less used to (there we go, Star Wars physics again!). Has someone got an even easier way of doing this calculation?

 

[TCR_500]

I'm not lying about what I know. You think I've only known that for a couple of days, well, I've known that fact well before I knew about Orbiter.

I do not believe that there is a law to use metric in spaceflight.

Depending on how hard you use the breaks, breaking efficiency may or may not be effected. However, if you lock them up on the Moon, sence there is less gravity, the tires won't heat up as much.

 

[RisingFury]

Depending on how hard you use the breaks, breaking efficiency may or may not be effected. However, if you lock them up on the Moon, sence there is less gravity, the tires won't heat up as much.

If you lock up the breaks on Earth, they wouldn't heat up either.
It's the friction in the break that causes the heat.

By the way, locking the breaks is not the most efficient way of breaking (even if your tires wouldn't blow up). If the wheels start to slide, the friction is lower then the force of static friction. If the wheels rotate and you're squeezing the breaks just hard enough for them not to lock up, your breaking force will be larger, however heating will be greater.

 

[Hielor]

And I've already known that 100 m is 328.08 feet. Just stop trying to make me use the metric system and drop the imperial system. It won't work.

See below comment about knowing the precise value of 100m. And if you want to use Orbiter, you need to use the metric system, or you need to convert everything. One of this is easier than the other (hint: it's the first).

Plus, your addons will be more widely understood and used if you use metric. The Orbiter community is an international community. Americans are the only ones who use the American system.

I'm using imperial units for the bases. It's what I know, and I know how to convert them.

So if you're having to convert the units anyway, why not just use metric in the first place?

I'm not lying about what I know. You think I've only known that for a couple of days, well, I've known that fact well before I knew about Orbiter.

You knew how many feet were in 100m (to the second decimal place), without looking it up, and yet you have repeatedly claimed to not know anything about the metric system?

Sorry, something there does not compute there.

I do not believe that there is a law to use metric in spaceflight.

Public law 418-100, section 5164: http://www.nist.gov/cfo/legislation/PUBLIC LAW 100-418.pdf

As has been mentioned several times, just because you do not know of the existence of something does not mean that it does not exist.

Depending on how hard you use the breaks, breaking efficiency may or may not be effected. However, if you lock them up on the Moon, sence there is less gravity, the tires won't heat up as much.

No. Because the gravity is lower, you won't be able to brake as hard without locking the wheels. And the tires will still heat up a fair bit from the friction, and since there's no air, they won't be able to dissipate the heat.

Just learn to VTOL land.

 

[ThatGuy]

I do not believe that there is a law to use metric in spaceflight.

Actually there is. Metric is the international standard system of measure. All scientists, even from the US, use metric. When you take a physics course, you will have to use metric.

 

[garyw]

Depending on how hard you use the breaks, breaking efficiency may or may not be effected. However, if you lock them up on the Moon, sence there is less gravity, the tires won't heat up as much.

Gravity has NOTHING to do with heat generated by BRAKES.

Modern carbon-carbon brakes use friction to slow down. With the sort of speed you will hit the runway on the moon you'll need more braking and the brakes will heat up quicker. Where would they then dissipate that heat to? You'll break the brakes.

As someone else pointed out - Hover land. I use brakes on the moon just to kill any small rolling movement I might have from aligning with the pad. That's it.

 

[Hielor]

Depending on how hard you use the breaks, breaking efficiency may or may not be effected. However, if you lock them up on the Moon, sence there is less gravity, the tires won't heat up as much.

Forgot to mention:
If you lock up the brakes, the tires will experience the exact same amount of total heating for a given ground speed on Earth (ignoring slowing due to drag/airbrakes) that they would on the Moon, it would just take longer on the Moon due to the lower gravity (which doesn't help, since you still can't dissipate the heat anywhere).

Why? Well, you have forward motion. You want to kill that forward motion using your brakes. The kinetic energy of your craft needs to go somewhere--and it turns into heat due to friction.

Since your landing speeds on the Moon will be higher, the total heating will be correspondingly higher, and you have no way at all to dissipate that heat due to the lack of atmosphere.

 

[TCR_500]

If you lock up the brakes, you will heat up the tires, not the brakes. There is a difference between the brakes disks and the tires.

And I never said I knew nothing about the metric system. I know just enough to convert feet into meters and meters into feet. Meters to Feet: <METERS> X 3.2808
Feet to Meters <FEET> X 0.3048. That's as accurate as I can get for now. Those are basicly the only two equations I use because they are the ones I use the most, the rest, I look up. Let's see, does orbiter measure fuel as weight (kg) or volume (L or kL). By the way, what's the formula for "carbon carbon"? And I still don't believe that there is a law about using the metric system. You're going to have to do better than just say that there is.

I'm not going to take out the runways. However, as I said before, I do have landing pads on that base. That gives you a choice. Just leave the big one to the Planet Hopper class star ship.

 

[ThatGuy]

Hielor gave you a link to the law. Fuel is measured in mass (kg) not weight

 

[Hielor]

And I still don't believe that there is a law about using the metric system. You're going to have to do better than just say that there is.

I linked you to the pdf of it, and told you exactly which one. Here:

Public law 418-100, section 5164: http://www.nist.gov/cfo/legislation/PUBLIC%20LAW%20100-418.pdf

As has been mentioned several times, just because you do not know of the existence of something does not mean that it does not exist.

Are you even reading your own thread?

 

[garyw]

If you lock up the brakes, you will heat up the tires, not the brakes. There is a difference between the brakes disks and the tires.

Incorrect. Disc brakes work by two carbon-carbon arms squeezing against a disc that's mounted to the tyre. The act of the carbon-carbon pressing against the disc generates heat through friction.

http://en.wikipedia.org/wiki/Disc_brake

 

[RisingFury]

If you lock up the brakes, you will heat up the tires, not the brakes. There is a difference between the brakes disks and the tires.

Yea, indeed.
Breaks are designed to take the heat. Tires are not.
Sure, you can lock the breaks so they don't heat up... but your tires will blow.

Besides... what the hell are you doing with wheels on such a huge ship? There's no way they'd survive such pressure.

 

[TCR_500]

Now exactly where does it say you must use metric? And why or how would it apply to a simulator?

If you lock up the brakes, the wheels are not moving. If the wheels are not moving, the brakes won't heat up. But the friction from the tires scuffing against the ground will heat up the tires. And I guess you didn't see the Sprint Cup race at Richmond. Those brakes were glowing bright red throughout the green flag runs even when the cars were accelerating. And the tires didn't heat up until the cars hit the corners at 110 mph from 160 mph. The brake disks did not over heat, they just turned red and stayed red until the next caution (about 100 laps or 75 miles). That's the length of a fuel run and is about 40 minutes. And locking up the brakes just blows out the tires, not the brake pads. If a stock car can have red hot brakes (litterally) for more than half an hour, heating up the brakes a little for a few seconds to stop an aircraft or space craft won't hurt any.

Ok, let's get back to the original topic. The bases. I've been thinking about putting a giant dome with an atmosphere in it. To save time on opening doors to let the space craft in, the doors will be made of plasma and will have an airlock disign. The plasma is held tightly by a magnetic field, loosens up and tighens up based on where the space craft is to let it through. I will let the craft through, but it won't let the air through. The question is, can it be simulated in orbiter, a pressurized dome big enough to take a space craft? Well, the suden air pressure increase will probably require the airbreaks and a steep pitch down to off set the lift. And don't worry, the air between the airlock (plasma) doors is re-captured by a fan after the craft is inside the dome. The only problem is re-capturing the air when a space craft leaves. I would need occaisional re-supplies every so often. Actually, sence plasma is basicly a gas without electrons, a space craft could punch through the field like it does air.

I'll have two of the bases out by the end of the week. Earth and the Moon.

---------- Post added at 05:47 PM ---------- Previous post was at 05:45 PM ----------

And for the tires on a Planet Hopper class starship, I said that the tires would be thicker than other aircraft/space craft to take the pressure. Plus the layered disign will allow one layer to blow off while the other layers stay intact. I got the idea from an exsisting tire disign.

 

[Hielor]

Now exactly where does it say you must use metric? And why or how would it apply to a simulator?

If you lock up the brakes, the wheels are not moving. If the wheels are not moving, the brakes won't heat up. But the friction from the tires scuffing against the ground will heat up the tires. And I guess you didn't see the Sprint Cup race at Richmond. Those brakes were glowing bright red throughout the green flag runs even when the cars were accelerating. And the tires didn't heat up until the cars hit the corners at 110 mph from 160 mph. The brake disks did not over heat, they just turned red and stayed red until the next caution (about 100 laps or 75 miles). That's the length of a fuel run and is about 40 minutes. And locking up the brakes just blows out the tires, not the brake pads. If a stock car can have red hot brakes (litterally) for more than half an hour, heating up the brakes a little for a few seconds to stop an aircraft or space craft won't hurt any.

Ok, let's get back to the original topic. The bases. I've been thinking about putting a giant dome with an atmosphere in it. To save time on opening doors to let the space craft in, the doors will be made of plasma and will have an airlock disign. The plasma is held tightly by a magnetic field, loosens up and tighens up based on where the space craft is to let it through. I will let the craft through, but it won't let the air through. The question is, can it be simulated in orbiter, a pressurized dome big enough to take a space craft? Well, the suden air pressure increase will probably require the airbreaks and a steep pitch down to off set the lift. And don't worry, the air between the airlock (plasma) doors is re-captured by a fan after the craft is inside the dome. The only problem is re-capturing the air when a space craft leaves. I would need occaisional re-supplies every so often. Actually, sence plasma is basicly a gas without electrons, a space craft could punch through the field like it does air.

I'll have two of the bases out by the end of the week. Earth and the Moon.

---------- Post added at 05:47 PM ---------- Previous post was at 05:45 PM ----------

And for the tires on a Planet Hopper class starship, I said that the tires would be thicker than other aircraft/space craft to take the pressure. Plus the layered disign will allow one layer to blow off while the other layers stay intact. I got the idea from an exsisting tire disign.

Plasma force fields?

Okay, so much for realism. Anyway:

 

[Nerull]

Plasma...does not work that way.

 

[insane_alien]

well, it kind of does, you get plasma windows in electron beam welding which is essentially a plasma forcefield to keep air out. however, the power requirements per square meter are phenomenal.

for one (no airlock design) big enough to cover a gap the proposed ship would be able to fit through you'd need more power than all available nuclear power plants.

and there is still leakage and you still have to consider that it is impossible to turn them off and back on again quickly. the ship would have to hover precicely for somewhere around an hour to get in or out.