The idea is that linked, fast-lifting electric drones would lift the rockets into the air at launch, saving a large proportion of the fuel. The feasibility of the concept is questionable, but it works with small-scale models.
Rammaxx, a drone company, specialises in a special type of autonomous aerial vehicle called RADs (rapid ascent drone), which replace fireworks with LED light painting, which are drawn in the sky by swarms of drones. The RAD’s design is optimised for short, but much faster than average ascents of up to 150 km/h and primarily for vertical flight, which, according to Dan Lubrich, the company’s CEO, allows a whole rocket to be lifted aloft, albeit not very high, to an altitude of around 5,000 metres, by linking up this type of larger drone.
The devices would then not work in swarms, but would be controlled by a central unit forming a super drone, eliminating the wobble caused by different lift speeds. This would require drones much larger than the current versions, with eight motor/rotors (one rotor 7 metres in diameter) and 2400 horsepower, which would be able to carry a payload of 6000 kg each at 500 km/h up to 5000 metres, according to simulations. It is not clear from Rammaxx’s description what the size and weight of the rocket itself would be, or how many drones would be needed to achieve lift-off, although a lower-than-average weight of the rocket would be expected, as this type of launch would require much less fuel and a smaller first stage, and would even eliminate (almost entirely) the first stage, according to the company.
Tests with current models have been successful, but it remains to be seen whether such powerful RADs could actually be built, and in any case the idea that autonomous devices could be used to launch aircraft has been floated elsewhere. Aveum is also developing what is billed as the world’s largest drone, which would carry rockets to 18 000 metres in orbit, but the concept differs from Rammaxx in that the Ravn X would be launched from a runway rather than vertically, and would not be electrically powered.
A less extreme idea comes from ex-Spacex engineers working at Talyn on a two-stage eVTOL/airplane combo, the first part of which would only help the electric passenger plane take off and reach the right speed.