I've considered this. IMTU, the Air/Raft is often part of a "Grav Train" system of linked vehicles, with computer controlls in the "slave" cars. One favorite is a flatbed or low wall conformable sled, no seats and minimal controls, perfect for hauling a 4 ton container. There are larger sleds for larger containers, giving a sort of "semitrailer truck" effect--but the big advantage of the 4ton sled is that it fits neatly above (or below) the air/raft in its hanger. If you have the cash, you get a much enhanced cargo-hauling capacity in the standard storage space.
Packing the Air/Raft
- Thread starter kilemall
- Start date
I've considered this. IMTU, the Air/Raft is often part of a "Grav Train" system of linked vehicles, with computer controlls in the "slave" cars. One favorite is a flatbed or low wall conformable sled, no seats and minimal controls, perfect for hauling a 4 ton container. There are larger sleds for larger containers, giving a sort of "semitrailer truck" effect--but the big advantage of the 4ton sled is that it fits neatly above (or below) the air/raft in its hanger. If you have the cash, you get a much enhanced cargo-hauling capacity in the standard storage space.
TL-F has cupholders that can keep the a drink both hot and cold simultaneously.
At TL-F you don't need a cup holder. There's simply a persistent gravitic field that keeps the cup stationary no matter where you put it, like above the steering wheel, to the right, just in front of the dash.
Condottiere
SOC-14 5K
Virtual coffee - the kick without the caffeine.
Or hot water.
Or cup.
Or hot water.
Or cup.
You can be a Coffee Achiever without any actual coffee being involved!
Straybow
SOC-14 1K
Or like riding in a Huey with the doors open. I never imposed the somewhat silly limit of 100 km/h. I could never figure why it wouldn't be able to go at light aircraft speeds. There are (or were) open cockpit aircraft that could go 300 mph.
Condottiere
SOC-14 5K
Biplane engines improved, as did airframe construction.
If you have vanilla anti gravity motors for a set technological level, they either need a system to tweak them, which I assume Tee Five does, or they need to be percentualized higher, to generate more lift per tonne.
If you have vanilla anti gravity motors for a set technological level, they either need a system to tweak them, which I assume Tee Five does, or they need to be percentualized higher, to generate more lift per tonne.
Atmospheric entry:
My take on that would be that they go geostationary and descend slowly at first, up to a maximum decent velocity before atmospheric heating by friction will become an issue, until in deeper atmosphere where normal flight conditions for the air/raft might be achievable without blowing everyone out of their harnesses
Atmospheric exit:
As long as they can achieve orbit without breaking anything or loosing anyone, it works
YMMV
That's close to my take on it.Atmospheric entry:
My take on that would be that they go geostationary and descend slowly at first, up to a maximum decent velocity before atmospheric heating by friction will become an issue, until in deeper atmosphere where normal flight conditions for the air/raft might be achievable without blowing everyone out of their harnesses
Atmospheric exit:
As long as they can achieve orbit without breaking anything or loosing anyone, it works
YMMV
Going up:
Straight up (drag-limited by the fact it's a barn door in a vertical ascent) until halfway up, then start lateral acceleration. Once you're halfway up, momentum carries you rest of the way up to orbital altitude. What takes most of the time is getting up to orbital velocity with only 1/10G of acceleration...
Coming down:
Deceleration at 1/10G (which is all that's available) to kill the orbital vector. Gradually increase the anti-grav to keep the vertical descent rate low. This allows time for the Air/Raft to slow to a survivable velocity before encountering the top of the stratosphere. Flip to belly-forward for maximum drag to kill remaining horizontal vector, then finish the descent in a flat orientation. Going down is faster than going up -- it's still a barn door, but it's a barn door with 1G downward acceleration, not 1/10G as it was on the way up. That said, every 1 second of free fall has to be countered by 10 seconds of upward thrust.
IMTU there's an optional ablative-foam heat shield re-entry kit -- wrap the big baggie around the Air/Raft, attach the stabilizing drogue ribbon to the upper lifting points on the hull, spray the foam and wait for it to set before starting the descent. Pretty contrail, impressive sonic boom. What doesn't burn away can be cut loose and ejected once you're down to a reasonable speed.
High TL Air/Rafts have integral heat shielding and a retractable aeroshell that deploys over the top. Watch your step when climbing out after landing!*
Most worlds would much prefer it if you didn't come in hot like that, though. Startles the livestock, annoys the neighbors.
* Handwave it if you want to, since Traveller ignores heat, pretty much (terawatt starship powerplants without radiator fins. Ok.)
Also, at high TL they probably have thrusters rather than plain grav modules so you can slam them to a stop from orbital velocity in minutes, then make like a potted petunia. ("Oh no, not again.")
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Condottiere
SOC-14 5K
Localized anti gravity generation is very much linked to local gravitational pull; equilibrium basically makes the vehicle a blimp.
Maybe that's why Air/Rafts are so expensive? Takes a lot of tech and design and what-not to figure out optimal removable seats.
Orbital velocities are for primitives
Was just reading through this thread and haven't read all the entries, so not sure if anyone has already said this, or even how relevant it is.
When Traveller materials talk about air/rafts reaching orbital heights I always assumed they were just talking about the height itself, not actually entering orbit.
My point is that with a technology that can control gravity to the extent shown in Traveller tech 10+, there is no need to enter orbit, i.e. achieve orbital velocity and let Newton do the driving. The air/raft, or any grav vehicle, including starships, can just hover over any desired point on the planet at any altitude (assuming one's Mdrive is strong enough).
Therefor reaching orbital altitude or reentering the atmosphere is MUCH easier than some posters have described, because you do not have to achieve/reduce orbital velocities at all, since you do not use such velocities in the first place.
Hope I have explained this well enough.
Was just reading through this thread and haven't read all the entries, so not sure if anyone has already said this, or even how relevant it is.
When Traveller materials talk about air/rafts reaching orbital heights I always assumed they were just talking about the height itself, not actually entering orbit.
My point is that with a technology that can control gravity to the extent shown in Traveller tech 10+, there is no need to enter orbit, i.e. achieve orbital velocity and let Newton do the driving. The air/raft, or any grav vehicle, including starships, can just hover over any desired point on the planet at any altitude (assuming one's Mdrive is strong enough).
Therefor reaching orbital altitude or reentering the atmosphere is MUCH easier than some posters have described, because you do not have to achieve/reduce orbital velocities at all, since you do not use such velocities in the first place.
Hope I have explained this well enough.
You explained this perfectly well, and I agree. Related: this is a thing that Star Wars gets right and CT gets wrong - there is no reason an un- or partial streamlined ship can't take off or land in an atmosphere. The vessel doesn't need to be travelling at high speeds for configuration to matter. Now, certain dispersed structures might be an exception to the above, but for most any close structure atmospheric entry can be managed with enough M-drive.
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Condottiere
SOC-14 5K
Just add a rocket for that last (mega)mile.
... and patience.
Ships and other things will likely still orbit rather than hover. It's fail-safe rather than fail-deadly, and planetary airspace control would just as soon not have to deal with ships falling out of the sky due to power plant or grav drive glitches. If you've got Maneuver Drives, even 1G can establish orbit or brake to a hover fairly rapidly.
But yeah, "streamlined" vs. "partially streamlined" vs. "unstreamlined" is a question of whether atmospheric entry/exit is supersonic, subsonic, or at walking speed. And in the last case, wind shear might rip off antennae or panels no matter how careful you are.
Yes, very good point about Newtonian orbits being fail-safe.
Taking that into consideration I'd suggest that an air/raft would be able to reach orbital altitude, but is probably not able to achieve orbital velocity. It would have to wait for a ship to pick it up.
Meanwhile spaceships would ordinarily follow the same hovering method to leave an atmosphere, then accelerate to a Newtonian velocity once outside the atmosphere, and conversely would slow down to hovering speed BEFORE trying to enter the atmosphere, thereby making such entries/exits fairly stress free.
This makes it sound like the only reason for streamlining is if one wants/needs to be able to zip around in an atmosphere at high speeds for some reason NOT related to achieving orbit or de-orbiting.
Now, what effect does this line of reasoning have on skimming Gas Giants?
Condottiere
SOC-14 5K
Essentially, it depends on how much the gravitational motors can bite on the local gravitational field.
I think in the MongoVerse its an arbitrary twelve hundred fifty klicks.
I think in the MongoVerse its an arbitrary twelve hundred fifty klicks.
It's sort of irrelevant exactly how quickly an Air/Raft can accelerate as long as it can maintain altitude -- in vacuum, the velocity keeps adding up and eventually it'll have enough to hold orbit. (V=A*T^2, since we're not decelerating to a stop after the midpoint.)
At 0.1G lateral acceleration, the Air/Raft should be able to reach the necessary 7.8km/sec velocity for a Low Earth Orbit (2000km altitude) in 2.6 hours if it starts in a dead hover at 2000km altitude.
I calculate it has that 0.1G lateral acceleration based on the description in Book 2 (120kph max, which the text suggests is limited by aerodynamics) and the vehicle design tables in Striker (120kph max speed for a grav vehicle requires 1.1G thrust).
Just to limit things a little, I also assume that 1G of the 1.1G is usable only to neutralize the vehicle's weight -- for example, on a world with 0.5G surface gravity the Air/Raft still only has 0.1G to use upwards or sideways, not 0.6.
Just to limit things a little, I also assume that 1G of the 1.1G is usable only to neutralize the vehicle's weight -- for example, on a world with 0.5G surface gravity the Air/Raft still only has 0.1G to use upwards or sideways, not 0.6.
