IISS Grav Bike design sequence

[gilthy]

Hi,

Some of my players were interested in getting grav bikes, and (as they were at Bulhai Freeport, Blue system, described in the Pirates of Drinax set) I decided there were some "surplus" IISS Grav Bikes for sale (for a slightly outrageous price, certainly as they were "used", i.e. 20+ years old). Good negotiation skills brought the price down. But I digress...

I was using the IISS Grav Bike from JTAS 6 (as it has MgT2e stats, unlike the one in my Grand Census DGP book from... way back).

However, looking over the stats, they are chunky and expensive.

So I decided to see if I could figure out how the IISS Grav Bike was built, reverse engineering them from the description to the Vehicle Handbook.

Basic = TL 15
12 hull = 6 spaces = Light Grav Vehicle chassis
Traits = Open Vehicle = Open Frame. Discrepancy: Open Frame has 1-3 spaces, and this is 6 spaces. Hm.

1 Crew + 1 Passenger = 2 spaces
250 kg cargo = 1 space

Cost per space = Cr 30.000 + Cr 10.000 for an Open Vehicle

Range = 7.500 km, which is +50%, so probably Fuel Efficiency, so cost per space = +25%, makes it Cr (30.000 + 10.000) x 1.25 = Cr 50.000 per space.
6 spaces = Cr 300.000 for the chassis.

Now the equipment:
Autopilot (sdvanced) Cr 15.000
Communication System (advanced) Cr 250 x 2 for increased range = Cr 500, range = 10.000 km
- Encrypted Cr 4.000
- Satellite uplink Cr 1.000 (uses 1 space)
Computer/4 Cr 3.000
Control Systems (advanced) Cr25.000
Life support (short term) Cr 10.000 (uses 1 space, I guess? It's 'one space per 20 people or part of')
Navigation System (advanced) Cr 50.000

Sub total = Cr 108.500 for equipment

Sensors (advanced) Cr 25.000 (for range = 25 km, Elec DM +2)
- hardened: doubles initial cost
- increased fidelity: doubles initial cost, gives Elec DM +3 (uses 1 space)
- increased range: doubles initial cost, range increased to 250km
So total cost for sensors is either Cr 25.000 x (1 + 1 + 1 + 1) so Cr 100.000 or Cr 25.000 x 2 x 2 x 2 = Cr 200.000

So, adding up everything, I'm at either Cr 508.500 or Cr 608.500 (depending on how you handle the sensor components doubling the initial cost).

The JTAS 6 article claims a cost of Cr 843.500, so either I made a mistake, or the author miscalculated, or my Vehicle Handbook is missing some errata.

And on top of that, it's 6 spaces, where the Vehicle Handbook indicates an upper size of 3 spaces for an Open Frame (making all the additions that use 1 space unable to be fit, and also making it a bit less chunky by going back to 3 spaces, which would also reduce the Shipping to needing 1.5 tons instead of 3, which is almost as much as a regular air/raft).

Thoughts? What am I missing?

 

[swampslug]

There is some ambiguity in the wording of the cost of life support that could add Cr50,000 to your costs.

Short term life support is listed at Cr10,000 per space and consumes one space (per 20 people). What I think is not clear is if the cost per space is per space the unit consumes or per space of the vehicle. All the other options in the life support section determine their cost based on the number of spaces in the vehicle so it would be logical to assume that the life support cost is also based on the size of the vehicle meaning 6 x 10,000 = 60,000.

Using this interpretation (whether right or wrong) would add Cr50,000 to the cost (leaving a shortfall of at least Cr185,000).

 

[AnotherDilbert]

There is a grav bike in the Vehicle Handbook (p126). It's 1 Space for 1 driver.

If you want a two-person bike I would aim for 2 Spaces, and allow a small amount of cargo, something like saddlebags.

It you want life support, use vacc suits.

 

[gilthy]

There is a grav bike in the Vehicle Handbook (p126). It's 1 Space for 1 driver.

If you want a two-person bike I would aim for 2 Spaces, and allow a small amount of cargo, something like saddlebags.

It you want life support, use vacc suits.

Yep, I know that one exists (one of my players' characters owns one).

My post/question was mostly to try and follow how the Vehicle Handbook design sequence had been followed for the IISS Grav Bike in JTAS 6, and try and figure out what I was missing, or if there were discrepancies.

The one in JTAS 6 looks similar to the one from CT/MT, as described and shown here:
https://wiki.travellerrpg.com/IISS_Grav_Cycle

However, it's TL 15 instead of 12, and has a list price of Cr 843.500 (which is oddly specific) instead of the Cr48,000 mentioned in the wiki/Grand Census (or Cr 171.600 for the MT one in the World Builders Handbook).

 

[gilthy]

Still puzzling on this one.

I can get to the original cost if I make the Grav Bike both Open Frame and Streamlined, and count the Life Support cost double (as in, providing Life Support for two spaces, instead of "one space of Life Support"). However, in my thinking that would set the Agility to +6 (+1 base, +1 Open Frame, +1 Streamlined, +3 Control Systems - Advanced), and the speed to Supersonic (two bands above the "base" which is Very Fast due to the TL 15 chassis).

It... just doesn't add up.

One clarification that would be helpful (and which might be there, but I missed it) is what happens if you add several options that "Double base cost" for a component.
In this case, Sensors are Advanced, TL 13, Cost Cr 25.000. Add Hardened, Increased Fidelity, Increased Range. Is that Cr 25.000 x 8 (for x 2 ^ 3) or x 4 (for the base price "extra" for each component, plus the original)? Is that explained anywhere?

I'll see if I can do a version of the design for the IIS Grav Bike that (in my opinion) follows the Vehicles book a bit better later (and is smaller, and thus a lot cheaper).

 

[Icehawk]

Still puzzling on this one.

I can get to the original cost if I make the Grav Bike both Open Frame and Streamlined, and count the Life Support cost double (as in, providing Life Support for two spaces, instead of "one space of Life Support"). However, in my thinking that would set the Agility to +6 (+1 base, +1 Open Frame, +1 Streamlined, +3 Control Systems - Advanced), and the speed to Supersonic (two bands above the "base" which is Very Fast due to the TL 15 chassis).

It... just doesn't add up.

One clarification that would be helpful (and which might be there, but I missed it) is what happens if you add several options that "Double base cost" for a component.
In this case, Sensors are Advanced, TL 13, Cost Cr 25.000. Add Hardened, Increased Fidelity, Increased Range. Is that Cr 25.000 x 8 (for x 2 ^ 3) or x 4 (for the base price "extra" for each component, plus the original)? Is that explained anywhere?

I'll see if I can do a version of the design for the IIS Grav Bike that (in my opinion) follows the Vehicles book a bit better later (and is smaller, and thus a lot cheaper).

This is a very old thread now but:
I've a character whose pre-career event was "take up a hobby, get a skill" and who then failed to graduate from military academy. The skill they took was flyer which they later developed into grav vehicles, so they've decide their character failed out of academy because they became obsessed with grav bikes and grav bike racing. They shared the event with another PC.

Their characters are really into grav bikes. We're talking grav bike holo-posters up in their room on the space ship, constantly chatting to NPCs about grav bikes (whether the NPC is interested or not), etc.

So if anyone's built some more grav bike variants with the vehicle rules, I'd be interested if you'd post what you've done.

 

[Geir]

I did a couple of racing bikes (Aeon Flyer Stinger G/Bike series) for a patron encounter in the recent JTAS volume 8 (p. 31 and 32). They actually first appeared in volume 100 of Freelance Traveller (p. 44), which is, um, free.

 

[Jetrock]

I translated the "Trasea" TL-12 grav bike from DGP's "101 Vehicles" (MegaTraveller era) into Mg2E stats to serve as the mounts for a small mercenary team, two fireteams of four bikes each, principally serving as scouts/recon elements for a larger fighting force. The standard bike was unarmed (but with a single hardpoint) and I liked the self-driving capacity (installed autopilot and improved navigation) which I figure makes better for a combat bike so the pilot can concentrate on aiming & scouting in autopilot mode. The stock model came without weapons so I added options for a Gatling laser, rocket pod, or tac missile (all in the 0.25 ton/1 space range) as standard for the grav bike, plus an integral laser carbine for target painting (in addition to scouts, a low-profile and quiet grav bike is ideal for forward observer/ortillery guidance duty.) The design was based on a 3-space TL-12 light grav vehicle with an open frame. I added a Computer/3 with built-in commo (improved and encrypted with a satellite uplink for communication with the merc team's ship, a 200 ton far trader), basic navigations and basic sensors, an entertainment system, advanced controls and advanced autopilot, improved camouflage (they're lightly armored so the secret to survival is not being seen), the integral laser carbine and then provision for one of the above mentioned 3 external weapons mounts with advanced fire control. I did add some armor (20 points) which is fairly tough for a cycle but not unreasonably tough--just enough to reliably deflect most small arms from the front or rear, but not enough to stop any sort of anti-vehicular weapons. The 3-space design is on the large end for a grav bike--I envisioned more of a Highway Patrol heavy bike vs. something particularly sporty, smaller than an air/raft or small ATV but big enough for a small heavy weapon and, in a pinch, a passenger. I figured the armor would keep max speed in the Very Fast class, but with a +5 Agility and the camo it's a tough target to hit. But if you can hit it, it's not likely to survive a second hit.

Their use in the game worked out pretty well--the PCs were preparing to pick a fight with a numerically superior but technologically limited force, and the grav bikes' tasks included mining a bridge, running interference for the main force, and most importantly, taking out the enemy force's two grav vehicles a pair of TL 9 Paladin-class grav tanks (adapted from the 101 Vehicles "Striker" class grav tank, a low-tech but incredibly tough design that can hold its own against light starship weaponry). Of course, the bike's weapons wouldn't even scratch the paint, but served well to guide in over-the-horizon anti-ship missiles launched from a pair of shipboard turrets scavenged from a previous mission and attached to a pair of Demeter grav wagons (I used the Mg2 gunskiff design, minus the guns, and then added back the guns to create a big TL-11 technical) to take out the tanks. The rest of the opposition force was stuck on the other side of the bridge once it blew (all wheeled vehicles!) One of the PCs, a Marine gunner/medic, had been tasked to ride out on a grav bike with a member of the team to mine the bridge, and ended up guiding in the missiles to hit the tanks, and now I think she's getting very obsessed with the idea of buying a grav bike--although my plan is for the mercenary leader to get into a conversation with her about the joys of Darrian grav bikes (laying some groundwork for a potential trip through Darrian space--plus, heck, I really like the Darrian grav bike designs from Aliens of Charted Space Vol. 3!)
Price worked out to about KCr250 not including the modular weapons package.

 

[gilthy]

I realised I never got around to posting the stats I used in the end.

The "complete package" uses the text + image from JTAS 6, and adds the following text + game stats:

The IISS Grav Bike has advanced Stealth and Camouflage systems. Note that the Camouflage does not affect the pilot or passengers, but it can be linked with advanced camouflage systems on their suits, where available. Stealth will hide all emissions from the Grav Bike and its riders.

TL	15
Skill	Flyer (grav)
Agility	+5
Speed (Cruise)	Subsonic (Very Fast)
Range (Cruise)	7,500 (11,250)
Crew	1
Passengers	1
Cargo	225kg
Hull	7
Shipping	1.5 Tons
Cost	Cr 737,000
Equipment
Autopilot	advanced, skill level 3
Communications System	advanced, increased range 10,000km, encrypted, tightbeam
Control Systems	advanced
Computer/5	Included Software
	Database, Intellect/2, Expert/2 (Navigation), Expert/2 (Computer/Sensors)
Life Support	oxygen/air tanks, 36 person-hours total
Navigation System	advanced, Navigation DM +4
Sensors	advanced, hardened, range 2500km, Electronics (sensors) DM +2
Ejection Seats	2
Camouflage	Recon DM: -4
Stealth	Electronics (sensors) DM: -4
Armour	Cerametals
Front	4
Rear	4
Sides	4

Included: Emergency softsuit x 2 (Central Supply Catalog p.21) 20kg;
Built in: Dual oxygen/air tanks (p. 41) upgraded to Enhanced Life Support (p. 27), providing 36 hours (in total, 2 × 18) of oxygen through the use of high-pressure tanks and recycling systems.

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