Mayfly Drone

[Lagrange]

Retry's Midge II made me curious about a dedicated bomber based on a small fixed-wing support vehicle. 

The Mayfly is a dedicated bomber using an internal bomb bay capable of delivering 3 small fuel air explosive bombs dealing a total of 60 points of area effect damage.  The Mayfly is used, typically en masse, to destroy ground targets, with a swarm of them flying in simultaneously to deliver large quantities of AE damage.  A Mayfly has not-great odds of surviving a bombing run against a prepared target, but the target is also likely to take very serious damage.  As a super-cheap system costing far less than it's bomb load, a low survival rate is fine.

The Mayfly has two deployment modes: in a counterinvasion role, it can swarm any enemy ground units and wipe them out rapidly for a far lower cost than most other approaches.  In an invasion role, Mayfly swarms can be deployed from dropships at high altitude from aerospace fighter bays.  From there, they can swarm down to dive bombing altitude (i.e. altitude 5) and destroy ground based defenses with any survivors returning to high altitude for pickup.

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Mayfly Drone

Mass: 4.89 tons
Frame: Unknown
Power Plant:  Fusion
Armor: BAR 3
Armament:
Manufacturer: Unknown
     Primary Factory: Unknown
Communication System: Unknown
Targeting & Tracking System: Unknown
Introduction Year: 3025
Tech Rating/Availability: D/X-F-F-X
Cost: 26,166 C-bills

Type: Mayfly
Technology Base: Inner Sphere (Advanced)
Tonnage: 4.89
Battle Value: 13

Equipment                                          Mass
Engine                         Fusion                 1
Safe Thrust: 4
Max Thrust: 6
Structural Integrity:         4                       
Heat Sinks:                   0                       0
Fuel:                         0                     0.0
Cockpit                                             0.5
Armor Factor (BAR 3)          8                   0.152

                           Armor   
                           Value   
     Nose                    3     
     Wings                  2/2   
     Aft                     1     


Weapons
and Ammo                 Location   Tonnage  Heat   SRV  MRV  LRV  ERV
Drone Operating System     BOD      0.989     -      -    -    -    - 
SV Chassis Mod             BOD       0.0      -      -    -    -    - 
Advanced Fire Control      BOD       0.0      -      -    -    -    - 
SV Chassis Mod             BOD       0.0      -      -    -    -    - 

Cargo Capacity: 3 tons

Features the following design quirks: Internal Bomb Bay, No Ejection System

Design decisions:
Drone or UAAV? Using a smart robotic control system costs less and frees up a ton for an extra bomb.   However, SRCS control has substantial drawbacks: gunnery is fixed at 5, there is no real coordination amongst units, targeting is iffy, and movement really only takes into account a target while ignoring other adversaries.   A drone system addresses all of these issues.  For example, a coordinated massed-attack likely improves survivability substantially by saturating air defense systems, veteran pilots can provide superior piloting, and more optimal targeting can be done.  There's a more subtle value as well: pilots with practice on drones become better.

The 4/6 speed gets the bombs to the target faster than a 3/5 speed and has only a modest cost (~3% of total system).  In particular, a 4/6 design can cruise at velocity 7 in atmosphere using safe thrust each round.  Velocity 7 is the maximum safe thrust for a propellor driven design.   This incidentally mildly improves the robustness of the design by increasing SI.

BAR 3 armor is slightly more expensive than a default of BAR 2, but it pushes the critical damage threshold up to 1 from 0, providing a modest increase in survivability against small arms for ~1% of system cost.

[Cavgunner]

Although velocity 8 is technically the max speed for a prop aircraft, such a design would also go out of control at that speed. Velocity 7 is the safe maximum for props. However, a thrust rating of 4/6 is still preferable to 3/5 in my opinion.

Drones are definitely under-utilized in Battletech. I always find designs like this interesting.

[Red Pins]

Ohh, tagged.

Drones are definitely under-utilized in Battletech. I always find designs like this interesting.

Yeah!  Getting ready for a project, gotta make a lot of them.  Every time I turn around, somebody else has another idea.  I think we need a thread for drones, I'll suggest it tomorrow,  actually.

[Daryk]

It's plenty cheap enough, especially since it CAN come back from a mission! :)

[Lagrange]

Although velocity 8 is technically the max speed for a prop aircraft, such a design would also go out of control at that speed. Velocity 7 is the safe maximum for props. However, a thrust rating of 4/6 is still preferable to 3/5 in my opinion.

Ah, thanks---messed up the rounding, updated.

[idea weenie]

I could see speed 8 being useful for performing maneuvers that need spare velocity.  You can only go a top speed of 7, but if you need to perform a maneuver that uses up 3 pts of velocity then you will have a final velocity of 5.

Think of it as a stunt remote control platform, with the extra thrust letting it dance in the sky.

[Lagrange]

There was a bug in my understanding---per SO errata, you need 1 ton of cargo space per bomb slot, even though the bomb itself only weighs a half ton.  Given that, it turns out that the weight of the improved smart robotic control system is not worthwhile.  This rule implies that you can store 8 bombs in 4 tons as cargo, but only engage in bombing runs with 4 bombs loaded in the same space.  A bit curious, but not unreasonable given that you'd like bombs to reliably deploy.

This does bring up a question: is it possible to carry a full 6 bombs?  Certainly not in small (<5 tons) vehicle, since you would need 6 tons of cargo.   It appears possible with this movement profile at 12 tons, but I'm skeptical that's worthwhile---in most cases you would prefer to have 2 small vehicles instead.

Upon further thought, I also decided to shift the design to be a drone.  It loses a bomb and costs marginally more, but gains very significant advantages.  Veteran pilots can provide superior targeting & control, drone pilots can coordinate massed attacks for improved survivability and lethality, and drone pilots can provide significantly superior target selection.  Altogether, this seems worth losing 1/4 of the bomb load.

[Red Pins]

Ah!  Errata!  Thank you, that was something I keep forgetting to check, it could have a significant impact on my own projects.

[Lagrange]

A minor tweak per Liam's Ghost's observation that you can use a pillion seat instead of a standard seat.  I used the freed mass to add a few self-defense weapons: 2 machine guns (short range) and a support laser (medium range).  These give the Mayfly some capacity to attack airborne targets.  It's not super clear this is worthwhile as the Mayfly remain very vulnerable to attack.  On the other hand, the 7k or so for the weapons is a small fraction of the cost when loaded with bombs and any hit on an opponent can be devastating in atmosphere.

You _should_ be able to eliminate seats altogether as crew requirements are automatically 0 with a drone, but that's not available in my version of MML.

[Red Pins]

Yeah, it’s the reason every design for my project needing to be hand-calculated.  It’s turning out to be a major issue.

[Liam's Ghost]

Seating for pilots may fall under "control systems" the same way a larger drone still needs its cockpit. We'd probably need a rule clarification to know if it's an error in the software or not.

[Lagrange]

Seating for pilots may fall under "control systems" the same way a larger drone still needs its cockpit. We'd probably need a rule clarification to know if it's an error in the software or not.

My copy of TO says:

A vehicle using a remote drone operating system is always considered to have a crew of 0 for construction purposes (regardless of its normal needs under the vehicle's construction rules).

That seems pretty explicit rules-wise.  In fact, I'm not sure how I could write something more explicit...

[Liam's Ghost]

Sure, but most units still require other control systems that are very crew shaped even if they aren't for crew in that case. Mechs and fighters still have to have their cockpits, and even large spacecraft have to allocate "crew quarters" to represent additional automation equipment.

I'm just saying that requiring a "seat" in a vehicle that isn't actually seating anybody could be the same concept.

[Lagrange]

Sure, but most units still require other control systems that are very crew shaped even if they aren't for crew in that case. Mechs and fighters still have to have their cockpits, and even large spacecraft have to allocate "crew quarters" to represent additional automation equipment.

I'm just saying that requiring a "seat" in a vehicle that isn't actually seating anybody could be the same concept.

I'm skeptical as the quote above contradicts this. 

I also found another---TM page 131 says:

...the chassis of a support vehicle contains its basic control systems...

So basic control systems are already included without seating for crew and we are already installing and advanced FCS for weapons.

Anyways, maybe ask a rules question if doubt remains?

[Lagrange]

Yet another tweak---after studying the rules, I think MML is wrong about medium weapons---in particular they have no aerospace range.

Given the above, I stripped the Mayfly Drone down to a minimum---it's a basic disposable bomber and not much else.

[Daryk]

You definitely understand One Way Attack (OWA) drones! :)