Proneutron
SOC-13
My first try at creating a vehicle using the Cepheus Vehicle Design System.
Cepheus Engine Only 6 person enclosed grav vehicle
- Thread starter Proneutron
- Start date
Proneutron
SOC-13
The weirdest, most interesting thing I discovered using this system to design a Grav vehicle is that you can increase base speed of a the vehicle by 500% via streamlining. That in itself is interesting. But the underlying ramification is neat. Since you are getting that speed increase by lowering your drag coefficient that means if you operate an air/raft, or any unstreamlined thrust based vehicle in vacuum conditions, you will have that base speed increase. Probably in a Trace atmosphere conditions as well.
This is my other hobbyhorse*: Air/Rafts can go very fast at very high altitudes. Long distance on-world travel (for Size 8, Atm 6-7; i.e., Earth) involves going straight up to an altitude of 100km (near-vacuum) and only then traveling horizontally. At that point maximum speed is limited to orbital velocity... (7.8km/sec). Descent is by retrograde antigrav thrust to safe reentry speed, then aerobraking to kill the rest of the horizontal velocity.
As I posted here:
"Basically, given the stated capabilities of an Air/Raft, it could reach any point on Earth (20,000km distance) within 4 1/2 hours: 1 hour and 15 minutes to 100km altitude, 3 hours above the atmosphere (would be 2 1/2 hours but escape velocity limits peak speed), and 15 minutes getting back down again. Average ground speed is 8000kmh. Shorter trips would have lower average ground speed since the climb/descent would be a larger portion of the trip.
A speeder built like a scaled-down X-15 could easily go Mach 3+ in atmosphere. But then, when an Air/Raft can effectively travel at Mach 6+ over the longest distances, why would you need one?"
Notes:
- "Mach 6+" as used here is a misnomer, as Mach numbers don't apply in vacuum.
- The much-shorter descent time is because upward acceleration is 0.1G and upward velocity is drag-limited below 30km altitude, while downward acceleration can be up to 1G (falling with the antigrav turned off).
- The answer to my rhetorical question is that you might need to go that fast over shorter distances, and punching through the atmosphere for a more direct route might be quicker than going above it. Sonic booms, though...
- Also, this means spending 5 hours in a vacc suit if you're using a standard Air/Raft.
- And 2.5 hours in 0.1G (under lateral thrust and braking thrust), with 30 minutes of 0-G in the middle. Depending on how hot the descent aerobraking is, it could be up to 3G for a few minutes.
*The first hobbyhorse is that IMTU the Type S has that huge fuel tank (LBB2 build rules) to support a Jump-1 after the first Jump-2, using TCS/JTAS#14 power-down rules and splitting the power plant fuel burn into weeks from the monthly rate.
Last edited:
Proneutron
SOC-13
This is my other hobbyhorse*: Air/Rafts can go very fast at very high altitudes. Long distance on-world travel (for Size 8, Atm 6-7; i.e., Earth) involves going straight up to an altitude of 100km (near-vacuum) and only then traveling horizontally. At that point maximum speed is limited to orbital velocity... (7.8km/sec). Descent is by cutting the antigrav and then aerobraking to kill horizontal velocity.
As I posted here:
"Basically, given the stated capabilities of an Air/Raft, it could reach any point on Earth (20,000km distance) within 4 1/2 hours: 1 hour and 15 minutes to 100km altitude, 3 hours above the atmosphere (would be 2 1/2 hours but escape velocity limits peak speed), and 15 minutes getting back down again. Average ground speed is 8000kmh. Shorter trips would have lower average ground speed since the climb/descent would be a larger portion of the trip.
A speeder built like a scaled-down X-15 could easily go Mach 3+ in atmosphere. But then, when an Air/Raft can effectively travel at Mach 6+ over the longest distances, why would you need one?"
Note that "Mach 6" as used here is a misnomer, as Mach numbers don't apply in vacuum. Also note that the answer to my rhetorical question is that you might need to go that fast over shorter distances, and punching through the atmosphere for a more direct route might be quicker than going above it.
*The first hobbyhorse is that IMTU the Type S has that huge fuel tank (LBB2 build rules) to support a Jump-1 after the first Jump-2, using TCS/JTAS#14 power-down rules and splitting the power plant fuel burn into weeks from the monthly rate.
Wow, I never thought of doing that with a grav vehicle to gain speed. Great idea. Ah, TCS. Something I never got to play back in the day. Makes sense for a Scout courier to get extra "legs".
Timerover51
SOC-14 5K
Just curious, did you use the vehicle design sequence in the System Reference Document or the Vehicle Design Guide?
Proneutron
SOC-13
It says, Cepheus Engine Vehicle Design System
Vehicle Design For A Classic Era Science Fiction 2D6-Based Open Gaming System
It has a cover picture of some 6 wheeled vehicle
It works because a canon Air/Raft can reach orbit. There's nothing saying you have to go all the way to orbit, though, and going partway gets you into darn-near-vacuum where 0.1G can add up to surprisingly high velocities.
Don't try this at low altitudes on an airless world though. It takes just as long to slow down as it did to build up the velocity in the first place, and with reaction times being what they are, and having only 0.1G to dodge with...
I didn't do much with TCS either. Once Douglas Lenat threw Eurisko at building TCS fleets in '81, I figured it was a solved game and lost interest. The special rules were useful, though.
From Wikipedia:
From Wikipedia:
Proneutron
SOC-13
Yes, my age addled brain just recalled that! Where he made that program that figured the winning order of battle fleet wise.
Getting old sucks. A few years ago I would have recalled that as soon as I read "TCS" in a post.
AnotherDilbert
SOC-14 1K
BA-Eurisko BA-K952563-J41100-34003-0 MCr13,030.385
2 G and Armour 18 isn't stationary nor lightly armoured...
The annoying thing he did was actually reading the rules and realising that he could build heavily armoured planetoids with the jump fuel in external drop tanks. As far as I understand that was what was specifically banned in the Tournament for the second year.
https://members.tip.net.au/~davidjw/tavspecs/best_tml/Starships%20(HG)%20-%20Professor%20Lenat%20and%20EURISKO's%20Winning%20Fleet.htm
Proneutron
SOC-13
Yes, yes! Now I remember. That was the key. Tons of armored rocks. Ya, 2G isn't stationary b y any means. Should have hired him for Assistant Secretary of the Navy for Research, Development and Acquisition
Condottiere
SOC-14 5K
I'm sorta weighing that option in relationship with planetoid configuration: I think the chances for damage to the tanks should be increased, because there can't be a clean separation.
Proneutron
SOC-13
Or maybe as the rock is broken up by significant hits the armor rating drops...?
Condottiere
SOC-14 5K
You're looking at around seven and a half percent of volume per armour factor, so while there might be some cosmetic damage, much as you can damage an already cratered exterior, I doubt it has a serious impact on the protective aspect.
Proneutron
SOC-13
Yeah, at that % range it wouldn't do much.
AnotherDilbert
SOC-14 1K
He simply ejected the tanks before combat. Work in the tournament, but not in a campaign.
Proneutron
SOC-13
I see what you mean
