General How do i convert Traveller Gs to miles per hour?

[Tiikeri]

The title says it all. How do i convert a traveller ship or grav vehicle's Gs to miles per hour?

If the ship or grav vehicle is on a 1g gravity world in a standard atmosphere, how do i compare how fast the ship is going with the sppeed of a jet or a rocket?

I found an acceleration converter online (1G is accelerating at about 21 mph per second) but i dont know how translate into mph cruising speed or max speed.

It would be great if someone can point out the relevant traveller book or other reference.

 

[AnotherDilbert]

How do i convert a traveller ship or grav vehicle's Gs to miles per hour?

The G rating is an acceleration or a thrust. In vaccum there will not be a maximum speed, but constant acceleration.

1 G ≈ 10 m/s², so after 10 minutes (600 s) the ship will travel at 6000 m/s (21600 km/h ≈ 13500 mph).

If the ship or grav vehicle is on a 1g gravity world in a standard atmosphere, how do i compare how fast the ship is going with the sppeed of a jet or a rocket?

In an athmosphere the constant thrust will be resisted by drag (air resistance), and produce a top speed.

MT RM p86 suggests this:

Note that top speed is modified by streamlining and atmosphere density.

So, an Airframe (winged) ship with a 2 G drive in a Dense atmosphere would have a top speed of 2120 × 90% × 75% = 1431 km/h ≈ 894 mph.

 

[kilemall]

I've been working this but from a different angle, more reentry at a delta vee of 1+ by CT terms (which is 10,000 km every 1000 seconds, or 10 km/s).

For a kilometer per hour conversion, that's 3600 seconds for 36,000 km/h, converting to 22369 MPH. So ya, even the pokiest slow of speeds in space translates to unsustainable fast in planetary atmosphere.



What I want to quantify is at what point the ship starts taking damage, what point that damage progresses to destroyed, and short of that how much the ship will slow down possibly damaging the crew and cargo if not secured and of course 'uncontrolled impact'. The numbers are scary.


Fastest manmade object to make it down in one functional piece was the Stardust RV bringing back samples. 12.6 km/s on a deep drop cause no powered alteration/retro, hit 46Gs slowing down to subsonic in 110 seconds, then deployed chutes for the landing.


So atmosphere is a MAJOR drag, pardon the pun. That ship is going to act more at grav vehicle speeds if it's not breaking atmo OTW offplanet.
Course you could break atmo, retro to a low fast orbit and reenter like a powered ICBM RV, could get around the speed barrier that way.

Modern missiles are up to Mach 8 and design goals of Mach 15-20 last I checked, so we can presume most hyperspeed atmo vehicles of a higher tech can attain that with sufficient thrust.


https://en.wikipedia.org/wiki/3M22_Zircon

 

[Tiikeri]

Perfect, that's exactly the kind of information I was looking for. Thanks guys.

 

[Grav_Moped]

...
Course you could break atmo, retro to a low fast orbit and reenter like a powered ICBM RV, could get around the speed barrier that way.

Modern missiles are up to Mach 8 and design goals of Mach 15-20 last I checked, so we can presume most hyperspeed atmo vehicles of a higher tech can attain that with sufficient thrust.

Not only retro to a low fast orbit, but also apply centripetal acceleration to achieve speeds well above orbital (escape) velocity. Apply reverse thrust at the end to drop velocity to something not totally insane before re-entry.