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Eole aerial launch platform - CNES, Perseus
by IKE 22-Jun-2011 12:52


EOLE has many similarities with Scaled Composites White Knight 1 and 2. All three are specifically designed as aerial launch platforms. The main requirement is the ability to transport a variety of payloads and drop them safely from a relatively high altitude. In order to accommodate the captive aircraft (like SpaceShipOne and Two), expendable rocket or even a re-usable rocket/winged vehicle there is a need for a centrally located big empty space. There the payload will be placed and then dropped. Also this area should be near the centerline and cq of the carrier aircraft in order for it to be insensitive to the weight of the payload or its absence after the drop.

The EOLE is a small-unmanned validation prototype. It will have a wingspan of 6,7m, a weight of 100kg and a payload of 50kg. It can fly up to 8km (~26k ft) with maximum speed of 0.6 mach. It will drop its payload at 4km while flying at 0.2 mach. The aircraft in the pictures is the even smaller scale model (1/2.2) made by Aviation Design. Eole will have two small turbojets with 45kg of thrust each while the scale model has two electric ducted fans with 5kg each.

As you can see in the comparative graph above (scaled to size), Eole (blue) is much smaller than White Knight 1 (red) or 2 (green). In the Perseus website they claim that this is an original configuration, although the tier one influence is obvious. Being unmanned it doesn’t need to accommodate a pilot, it may look similar to WK2 but its general arrangement and engine placement is closer to WK1. Due to its size it is strictly a research vehicle. It will be used to study the dynamic behavior during the separation and rocket launch. Apart from remote controlled take-off and landing it will fly autonomously within a range of 30km with its GPS assisted autopilot. Tests are already taking place with large part of the work conducted by students. The rocket drops and firing will be conducted next year or 2013 by DGA EM (Direction Générale de l'Armement - Essais de Missiles), the missile test sector of French armed forces.

Apart from EOLE , Perseus covers a variety of other projects mostly aimed at rocket propulsion and even complete launch vehicles like the ARES/ARCADIA. The HERA-F for example is a hybrid rocket that use oxidizer and solid rubber fuel (multi-core polyethylene or single-core paraffin). SpaceShipOne used a similar motor, it may not have the performance of a solid rocket booster but it is much safer because it can be stopped and started at any time by throttling the oxidizer. It is also much simpler than a throttled liquid fuel rocket. Other concepts cover multi-staged rockets and fuel containers.
Virgin Galactic also have hinted the use of White Knight Two as a platform for launching expendable or reusable rockets that could place satellites to orbit. The images above show the ‘LauncherOne’ on the right; a two stage expendable rocket (image from Virgin Galactic) and the two concepts on the left show a possibly reusable winged orbital vehicle (images from a Virgin Galactic presentation via Flightglobal).

The goal of Eole and Perseus in general is to stimulate space transport innovation throughout the new generation of engineers. By itself it won’t bring a product or service to the market but not unlike Scaled Composite and Paul Allen funded Tier One that led to Virgin Galactic, Perseus may spin-off a variety of innovative companies that may be the European VG or Space-X.

(EOLE images/drawings : CNES , WK1-SS1/WK2-SS2 images/drawings: Virgin Galactic)

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