The Workhorse
by Biggie
uploaded 2015-04-19
mod spaceplane
#Heavy #Cargo #SSTO
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Frontal View

Rear View

The Workhorse with 73 ton payload loaded into cargo bay

Taking off with 73 ton payload, loading jacks assisting

Performing orbital injection with payload

Achieved over 100km orbit

Payload delivered, awaiting descent to KSC but forgot to transfer fuel

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  • Type: SPH
  • Class: spaceplane
  • Part Count: 276
  • Mods: 6
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  • B9 Aerospace
  • KAS
  • KWRocketry
  • MagicSmokeIndustries
  • ModRocketSys
  • Squad (stock)
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The Workhorse is a highly specialized, very large spaceplane designed to take heavy cargo into orbit as cheaply as possible. Its rigid frame is capable of easily lifting a payload weighing up to 70 tons into orbit in its 8x8x9 meter bay to a circularized orbit above 100km and return safely to KSC at only the cost of fuel. This is the only craft I’ve seen capable of achieving that feat.


Rigid frame, Highly stable flight, Easy takeoff, Single stage operation up to 150km orbits (with payload, can return), Payload size up to a theoretical maximum of 8 cubic meters, Payload weight up to a theoretical maximum of 80 tons, RCS for small maneuvers in orbit, Closable cargo bay doors/loading ramp, Payload loading assistance, Symmetrical payload loading, Payload stabilization and docking, Containers for additional KAS part storage (just in case), Powered wheels for driving on land, Pretty lights.


After failing to fit a bunch of cargo into the stock cargo bays, I decided to build my own. The Workhorse has an extremely large cargo bay, routinely capable of lifting a payloads greater than 3.5m in diameter and weighing more than 50 tons. Cargo is spawned in first, and must be moved off the runway on its own power or using a separate towing vehicle. Cargo can then be loaded and secured using the front cables (from Kerbal Attachment System) found in the cargo bay. These cables are a far more reliable means of securing the cargo than docking ports, however they take time to attach to the payload at multiple points. The easiest way to load the cargo is to use the cable winches to pull it into the cargo bay. The loading jacks can be used to adjust the height of the front section of the plane, assisting in loading and in takeoff. Make sure to lift the cargo somewhat using the overhead cables, then and only then switch the plug mode of one of the cables to docked and quicksave, failure to do so will result in the loss of cargo when reverting to last quicksave. The kerbal that did the attaching may reenter the cargo, or he may use the seat next to the cargo bay ladder. Failure to at least partially close the cargo bay doors will almost certainly result in a tail strike upon liftoff. Before takeoff I recommend retracting the loading jacks as well, once you achieve a velocity of greater than 100m/s, extend the jacks. This will push the front end of the craft into the air, allowing for an easier liftoff, although this is not necessary. The Workhorse is powered by 4 Sabre M engines, each fed by 2 Sabre M intakes. This provides the unloaded aircraft with a greater than 2:1 thrust to weight ratio. The unloaded plane is nearly 200 tons, meaning a cargo of 100 tons would have to be loaded to lower the TWR low enough to lower the vertical climb rate to an unacceptable speed. the routine 50 tons can be flung straight into the upper atmosphere before the high speed phase is initiated. In order to achieve orbit, I recommend ascending to 20km as fast as possible, then reducing your climb rate to a crawl. From 20km to 30km, you should accelerate from your cruising speed into the hypersonic regime. When approaching 30km (you should be going 1400m/s at this altitude), carefully watch your intake air, when it gets low switch one set of engines to rocket mode and begin your orbital injection. Allow the jets to continue working for you until flameout, then quickly switch modes, you will recover easily if you’re quick. If you did it correctly you should be able to take a 50 ton payload to 150km and return to KSC without taking a drop of its fuel. The craft is designed to take off with heavy cargo in the back and land with only a small amount of fuel left, this ensures the center of lift and the center of mass are properly aligned during the entire flight. It is quite capable of taking off empty and landing fully loaded, although the latter is significantly more difficult. In the case of an emergency I would recommend ditching the payload and dumping your fuel before landing. Use the parachutes only in the case of an otherwise irrecoverable rate of descent. This should be easy to avoid if returning from a cargo delivery, the craft will be balanced and feel light. Yawing is unusually effective for this craft as well, use it liberally in your descent. I recommend undershooting the KSC during your descent to avoid the need to U-turn a 200 ton plane (minus all the fuel you’ve used though) but in the event you do, applying the air brakes on turning dramatically reduces your turn radius. Again, I recommending using yaw over rolling and pitching though. The thing lands like a dream, the hard part is stopping it once it’s on the ground, it’s like a train. Use the airbrakes liberally and the parachutes only as a last resort, they are for emergencies only.

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