Bureau d'Etudes Dassault
Pélican Slew Wing Space Plane
Laurent Esmiol for correcting my French. David Gillon for historical information on slew wing designs and the inspiration to design an interface biplane. Dan Hebditch for "historical" consistency.Contents
The Dassault Design Bureau, named for Marcel Bloch/Dassault (1892-1986) the twentieth century French aircraft pioneer, of the Mechernene et Baali industrial conglomerate has a long history in the production of interface vehicles. One of their most popular models is the Pélican which, in various versions, has been in production for over sixty years.
The Pélican has a slew wing which is a top mounted wing that rotates around its centre. For low speed flight the wing is at right angles to the aircraft body but as the speed increases the wing rotates improving its performance in supersonic and hypersonic flight. This is the same principle used by swing wing aircraft where the two half wings can be moved towards or away from the aircraft body to alter the overall wing geometry.
The troops glanced nervously around themselves as they shuffled past the growing pile of gear on the taxi-way, discarding equipment that only a few hours before they had been relying on to keep them alive. A distant crump caused them to flinch in unison but they were distracted by the growing roar of the incoming space plane.
The Dassault Pélican thundered overhead, surprisingly slowly for a space plane, with its wing fully rotated and its landing gear down. It thumped down on to the runway, slowed and taxied towards the front of the line of troops awaiting evacuation.
Once it came to a halt the Pélican's nose dipped down, the lower half of its nose split apart and the loading ramp began to descend. The exhausted men began to move forward as the MSIF load master waved them forward into the belly of the space plane. From my vantage point a little way away it looked as though a dragon had descended from the sky and was devouring a group of docile humans. The load master's shouts distracted me from my daydreaming. A group of men had retained their personal equipment and their NCO was arguing with the load master.
I sidled over in an attempt to overhear without attracting the attention of the nervous, angry and well armed group.
"We've got no
orders to abandon our gear!" protested the corporal.
As I filed on board five minutes later, at the back of the line, I passed a small pile of military equipment which disappeared from view as the Pélican's ramp withdrew and the nose closed around us. Never in my life had I been so glad to hear the sound of a door closing.
Slew wing spaceplanes first became a practical proposition with the advent of adaptive wing morphology (AWM) in the early 2200s. AWM allows the shape of a wing to be altered by twisting and stretching the wing rather than by adding mechanical devices, such as flaps, to alter the shape (and hence the flight characteristics) of a fixed geometry wing.
A slew wing consists of a single wing that pivots horizontally around a central point fixed to the aircraft body. This gives the aircraft a variable wing geometry that greatly improves its flight characteristics in different flight regimes. Variable geometry wings are nothing new and the swing wing aircraft dates back over 300 years to before the Twilight War.
In 2223 the Dassault Design Bureau began the development of a variable geometry wing interface vehicle intended for both cargo and passenger duties. The variable geometry wing has significant advantages over the standard delta wing design for a space plane. A delta wing design has very high landing and take off speeds as its wing is designed to be most efficient in supersonic and hypersonic flight. A variable geometry wing (swing wing or slew wing) however gives much better subsonic performance thereby greatly reducing landing and take off speeds and consequently significantly reducing the length of runway required.
Dassault considered both swing and slew wings for their design and finally settled on the slew wing. The slew wing is mechanically much simpler than the swing wing (once AWM can be utilised) making it both cheaper and more reliable. Additionally the slew wing can be stored along the length of the fuselage (without the need to include folding wing designs which add complexity and weak points to the design) thus significantly reducing the hanger requirements for the the vehicle and improving access to docking ports.
Propulsion for the vehicle was provided by a hybrid jet and rocket system. During atmospheric flight (subsonic/supersonic/hypersonic) four air breathing jet engines were utilised. A variable geometry air intake system, utilising the same adaptive morphology technology used in the wings, allowed the engines to operate over the very wide range of airspeeds. In addition thrust reversers were fitted to further decrease the required landing distance. A hydrogen and oxygen fuelled aerospike rocket system was also provided for out of atmosphere operations and to provide the final boost to orbit.
In common with other interface vehicles of the time the Pélican was designed with a variety of command options. The standard version was unmanned and intended for operation in the well controlled and regulated interface environments of Earth and Tirane. Piloted and remotely piloted versions were also available (at the expense of cargo capacity). The piloted version had no conventional cockpit with direct visibility instead a pressurised pilot cabin at the rear of the cargo bay was provided with all visual inputs provided by cameras. In effect the piloted version of the Pélican was identical to the remotely piloted version with the remote control station fitted in the cargo bay and hard wired into the controls rather than communicating via radio.
The first prototype (which had no aerospike rocket) flew in 2229 and the first flight to orbit was achieved in 2231. In 2233 the Pélican was finally certified for operation by the Direction de Surveillance des Véhicules Aérospatiaux (DSVA : Aerospace Vehicle Supervisory Department of the French Transport Ministry) under either manual or automatic control.
The Pélican was originally designed and marketed as a civilian interface transport and its relatively short take off and landing abilities made it a popular choice for operations from regional airports. Those same abilities also made the Pélican attractive to military and colonial authorities and in 2235 a combined French Colonial and Defence Ministry contract was given to Mechernene et Baali to produce a modified version of the Pélican.
The Pélican C40 was designed to be much more robust and have improved maintainability for service in the colonies. A nose door option to allow the transport of large cargoes was also included. The C40 was purchased in considerable numbers as the standard interface vehicle for the French colonial programme.
Over the sixty years since the Pélican first flew a bewildering range of upgrades, enhancements, modifications, engine options and adaptions have been produced however the basic form of the space plane remains unchanged.
|Arrangement of Primary Systems|
Above General arrangement of the main components of the Pélican Slew Wing Interface Vehicle. Courtesy of Mechernene et Baali.
The Pélican's main body consists of a streamlined, flattened, cylinder that bulges out at the mid-section. The four jet engines are housed (two per side) in the central bulge. The front of the bulge incorporates the air intakes while the rear accommodates the exhausts and the thrust reversers. The aerospike rocket motor is mounted in the rear of the main body. The overall shape of the fuselage was designed to allow limited aerodynamic control during reentry when the main wing was not deployed. At the rear of the main body, above the aerospike, are two angled tail fins.
The main wing is sited above the main body and connected to it via a rotating axle, the wing (when aligned with the body) lies completely within the outline of the body. The wing and axle are designed such that the wing can be easily removed from the body to facilitate maintenance of both. The Pélican's wing uses adaptive wing morphology (AWM) to provide aerodynamic control and is actively cooled at both wing tips to allow for the heating effects of hypersonic operation. The wing is almost completely self contained requiring only power, flight data and a mechanical connection to the main body. The wing is remarkably light weight in construction however unlike most other designs of aircraft it contains no ancillary systems such as fuel storage, engine supports or landing gear.
Fuel tankage and landing gear are housed in the belly of the main body while the avionics and other ancillary equipment are in the upper part of the nose (to counter balance the rocket motor).
Pélican's are available with a range of engines from a variety of suppliers according to the customers specification.Common Variants
Above A flyby of the three current models of the Pélican at the 2301 Mirambeau Air Show. Pélicans from the French Colonial Ministry (C-98 top of picture), Air Dakar (B-93 middle of picture) and the MSIF (M-96 bottom of picture) took part. All three have their slew wings in the fully extended position for the low speed pass. Courtesy of Tirane Aeorspace Publications, New Wellon Press.
Many versions of the Pélican have been produced in over sixty years of continuous development and production. Some of the most common are listed here.
Pélican A & B : Civilian Transport
The original A version of the Pélican was replaced by the B version in the 2240s which built upon the experience gained over a decade or operation and some of the lessons learned in producing a colonial version of the Pélican (see below) . The B version is intended for use in the core (usually under automatic control) with access to high quality ancillary services and maintenance facilities. Passenger versions are fitted with a forward fuselage airlock on both sides of the main body while cargo versions have large forward side doors that require terminal facilities for loading and unloading.
The Pélican A is no longer in production and there are no known aircraft still in commercial operation. The current civilian model is the Pélican B-93.
Pélican C : Colonial Transport
The C version of the Pélican was originally produced to a joint military and colonial specification in 2240. The design took the basic airframe from the A version and reworked the equipment to improve ruggedness, maintainability and reduce dependence on terminal facilities.
In flight there is little to tell the B and C variants apart however on the ground there is no mistaking the two. The C variant has considerably heavier duty landing gear to accommodate the variable quality of colonial runways and most obvious of all is the nose door and ramp that allows direct vehicular access to the Pélican's cargo hold.
Other differences are more in the details, the only major variation is that the jet engines can be serviced from inside the cargo hold (rather than externally as in the B version). Indeed the engines can be dismounted directly into the cargo hold allowing maintenance without the need for hanger facilities.
The Pélican C is the main interface transport for the less developed French colonies (namely Beowolf, Kimanjano, Alderhorst and Aurora). It is also a popular choice for other colonial powers and private enterprises on the French Arm due to the good availability of spares and service facilities.
Above A Pélican C-78 on the runway at the Mechernene et Baali test facility outside Dakar, Nouvelle Provence, Tirane. The vehicle is undergoing final quality assurance checks following upgrading prior to release to the customer. The Pélican is in the French Colonial Ministry's high visibility colour scheme and the registration number indicates that it is bound for service on Kimanjano.Courtesy of Mechernene et Baali.
Numerous versions of the Pélican C remain in service throughout the French Arm indeed some of the older models have had the aerospike rocket motor removed and are used as conventional (albeit rather inefficient) hypersonic transports. The current colonial model is the C-98.
Pélican M : Military Transport
The French military originally used the colonial Pélican C as its main interface transport. In 2276 however the Colonial and Defence ministries were unable to agree on a common specification for the upgrade to the C-62. The reason for the split with the Colonial Ministry was that the military wanted significant changes to the C-62 design while all that the Ministry required was an evolutionary upgrade to take account of advances in technology. Instead a combined Armée de l'Air (French Air Force) and MSF (French Republican Space Navy) specification was produced in 2278 which Dassault developed into the Pélican M-80.
The military specification called for significant improvements in the Pélican's survivability in combat conditions.
While the nose and tail sections of the M-80 were outwardly similar to the C-78 the central section was completely redesigned. The most significant change was the addition of a second slew wing below the main fuselage. The lower wing (which was smaller than the upper) required significant alterations to the load bearing structure of the centre section, making it slightly more boxy in appearance, and to a number of ancilliary and control systems. In addition the M-80 also utilised advanced composite materiais and incorporated an armoured hull, stealth technologies, a comprehensive countermeasures suite and secure communications. In fact the modifications were so radical that the M-80 was effectively a completely different aerospace vehicle to the C-78. Political and budgetary reasons however made it expedient for the Defence Ministry to sell the M-80 as a simple upgrade consequently the Pélican name was retained.
The addition of the second wing caused numerous difficulties during development, particularly during re-entry when the lower wing was subject to the full heat of aerobraking. Early versions of the M-80 (known as the M-80A) actually entered service with slewing of the lower wing disabled. Continued development, and additional funding, eventually rectified the problems with the M-80C and an upgrade programme converted the existing M-80A Pélicans to C standards. Versions of the M-80C were exported to a number of French allies throughout the 2280s and 2290s.
The M-80C is still in service with a number of second-line units of the MSIF Escadre d'Interface (Imperial French Space Navy Interface Fleet) but is being gradually replaced by the M-96 in French service.
The Pélican is a workhorse interface vehicle capable of operating from relatively short runways and (in the C and M versions) without extensive terminal and support facilities. This ability is bought at the expense of overall payload limiting the Pélican to niche roles (operating from regional airports rather than major spaceports) in the core. In the colonies however the Pélican comes into its own and is the most common lander in the French Arm.
The Pélican can be based either in orbit (either from an orbital terminal or starship) or on the ground depending upon the local facilities.
The cargo hold is highly adaptable and can be fitted out for passengers, containerised cargo, palletised cargo, vehicles or various mixtures thereof. Loading in orbit is affected via the side docking ports, allowing transfers to occur in a shirt sleeve environment. For the C and M versions loading can also be carried out in vacuum (usually with containerised cargoes) via the nose door.
Above A Pélican M-96 in low orbit with wings in hypersonic configuration. The wing tips only protrude slightly over the side of the fuselage giving aeodynamic control during re-entry. Note that the upper and lower wings slew in opposite directions.The aerospike rocket nozzle is visible at the rear as are the port jet nozzles (the air intake is obscured by the upper wing).Courtesy of MSIF Media Ops.
Descent is initiated with a de-orbit burn on the aerospike rocket with the slew wing in the zero degree position (aligned with the main body). The Pélican then uses aerobraking to reduce its speed to hypersonic velocities whereupon the wind is slewed to a thirty degree position to improve aerodynamic control and lift if necessary. At this point the Pélican's jets can be started in scram jet mode if significant cross range flight is required. As the landing site approaches, and the airspeed is reduced, the wing is rotated further to increase the lift and improve the low speed performance. By the time subsonic speeds are reached the wing is at right angles to the body. Final approach is made under jet power, to allow a go-around if there are any difficulties, and following touch down thrust reversers quickly slow the Pélican to taxiing speeds.
Above A Pélican M-96 on final approach to the runway. Both upper and lower slew wings are fully deployed to give minimum stall speed. Landing gear is down and the various navigation lights are clearly visible in the dusk. Courtesy of MSIF Media Ops.
Unloading and loading on the ground can occur either via terminal facilities, or the nose door on the C and M versions. While parked, either in orbit or on the ground, the Pélican is normally stored with the wing, or wings, in the zero degree position to reduce the space requirements. This ability also makes docking manoeuvres with orbital facilities much simpler and greatly reduces the cost of hanger bay facilities.
To return to orbit the Pélican (with the wing in the ninety degree position) takes off from the runway under jet power and accelerates to supersonic (> Mach 1) and then hypersonic (> Mach 10) speeds as altitude increases. As the speed increases the wing angle is reduced and the air intakes reconfigured to accommodate the increased air flow. Once the Pélican reaches its ceiling for air breathing operations the aerospike rocket is ignited, and the jets are shutdown, to obtain orbital velocity.
Civilian Service in the Core
The Pélican has been in service, primarily with regional interface lines and the national carriers of secondary space powers, for over sixty years. With the exception of the A series which suffered a number of maintenance problems with the main wing axle the Pélican has proved a reliable vehicle popular with both customers and owners.Colonial Service
The Pélican became the primary interface vehicle for the French colonial effort in the mid 2240s quickly displacing older models. The French Colonial Ministry has retained its preference for over fifty years, often through bureaucratic inertia rather than overwhelming technical superiority, making the Pélican one of the most widely recognised symbols of life outside the core.
The French preference, and the resultant availability of spares and maintenance expertise on the French Arm, has also made it a popular choice with other colonial powers. The steady development of the Pélican C has also improved its performance in colonial service greatly reducing the maintenance and infrastructure costs relative to its main competition. This is primarily because most alternate colonial landers are based on either civilian models designed for operation in the core or military models both of which tend to have relatively high maintenance and/or infrastructure requirements.
The Pélican's slew wing design also allowed the construction of a rotating docking port as part of the orbital terminals allowing colonists to be transferred under spin gravity.
Above A Pélican C-98 in French Colonial Ministry colour scheme approaching the rotating docking cylinder in low orbit over Kimanjano. The Pélican is aligned with the axis of the cylinder and the docking platform has been extended outwards from the dock and is being raised to lock onto the Pélican's landing gear.Three other Pélican can be seen already docked (in the two o'clock, seven o'clock and ten o'clock positions). The Courtesy of Colonial Ministry Press Office.
The core of the docking port was a rotating (at 2.77 rpm to give a 0.3G spin gravity) 70m diameter cylinder connected to the spin section of the terminal at one end with the other end open to space allowing the Pélican to enter along the cylinder's axis. The Pélican would first align itself with the central axis of the docking port and spin around its axis to match the spin of the port. The Pélican would then enter the port, with its landing gear extended, and dock with a landing frame. The landing frame and attached vehicle would then be moved radially outwards towards the cylinder wall (landing gear outermost), thereby gradually increasing the spin gravity experienced by the vehicle. To balance the changes in angular momentum a liquid ballast system pumped mass from around the outer radius of the cylinder to to the point on the radius opposite the interface vehicle. A system of flywheels was also used to maintain the spin of the docking port at 2.77 rpm (moving the mass of the Pélican from the axis to the outer radius would otherwise reduce the spin of the port).
Once the Pélican had been "lowered" to the outer radius of the docking port (now resting on its landing gear) the side airlocks were connected to the pressurised area of the docking port. The colonists were then able to easily board without having to leave the pressurised, spin gravity region of the port. Once the colonists had boarded the Pélican was "raised" back to the port's central axis (and zero gravity), released from the support frame and launched back into space. The docking port's ballast and flywheel systems operating in reverse to accommodate the changes in angular momentum.Military Service
The Pélican C-42 entered service with the Armée de l'Air and MSF in 2244 as their main interface transport on Earth and Tirane. The Pélican's were used to transport military personnel and equipment to and from orbit and were used only in a rear areas logistical role rather than in any combat operations.
In the late 2260s the C-62 was introduced to replace the aging C-42 on Earth and Tirane. Following a refurbishment programme a number of the C-42s were distributed amongst the MSF's colonial Naval Stations.
The advent of the M-80 in MSF service in 2282 allowed the use of the Pélican closer to the front line in military interface operations. The M-80 was tasked to provide third wave interface support during orbital assault operations as part of the then developing Division de Debarquement concept. The first M-80s saw combat operations during the Elysian rebellion in 2290 and proved a considerable success, albeit against very limited opposition. The War of German Reunification (2292 - 2293) proved the utility and durability of the Pélican as troop redeployments were carried out throughout the French Arm in response to real or imagined German threats.
The formation of the Escadre d'Interface (EdI) in 2287 brought all the Pélicans in French service under a single command and resulted in some rationalisation in their deployment during the later 2290s. This resulted in the equipment of all regular EdI Pélican units with the M-80 while reserve units acquired the remaining C-62s.
The Kafer War, and the large number of orbital assaults and evacuations that it has entailed, has demonstrated both the strengths and weaknesses of the Pélican in orbital assaults. The Pélican's ability to use relatively short runways has made it invaluable in operations where the planet's main spaceports are either damaged or under enemy control. Also the ruggedness and easy maintainability of the design has allowed high availabilities even during extended periods of high intensity operations. On the debit side however the Pélican M-80 has proved to be very vulnerable to both air to air and ground to air attack both in terms of avoiding contact and surviving damage.
The M-96 currently in production has been redesigned (as the M-96B) to take account of the lessons learned in the Kafer War and initial reports suggest that the improvements are having the desired effect. The EdI are currently introducing the M-96B into front-line units and upgrading reserve units with the displaced M-80s.
|Statistic||Units||Civilian B-93 Value||Colonial C-98 Value||Military M-96 Value|
|Main Power Plant||4 of 0.5MW Old Commercial MHD Turbines, thrusters fitted.|
|Secondary Power Plant||Linear Aerospike Rocket|
|Auxiliary Power Plant||0.01 MW New Commercial Fuel Cell|
|Hull Material||Synthetic||Advanced Composite|
|Other Equipment||None||Nose door and loading ramp||Nose door and loading ramp, Armoured (2) Hull, Extensive Masking|
|Reflected Signature||Radial (Wings Folded)||2||2|
|Radial (Wings Deployed)||3||2|
|Lateral (Wings Folded)||7||4|
|Lateral (Wings Deployed)||8||5|
|Power Plant Hits||11|
|Target Profile||Radial (Wings Folded)||-2|
|Radial (Wings Deployed)||-2|
|Lateral (Wings Folded)||-0|
|Lateral (Wings Deployed)||-1|
|AWM||Adaptive Wing Morphology - various technologies that allow the shape of the wing to be changed in fligh without the use of additional devices such as flaps.|
|Dry Weight||Total weight of the vehicle without cargo or fuel.|
|DSVA||Aerospace Vehicle Supervisory Department of the French Transport Ministry|
|EdI||Escadre d'Interface - the branch of the MSIF responcible for interface operations.|
|GLOW||Gross Lift Off Weight - Total weight of vehicle, fuel and cargo at lift off.|
|MSIF||Marine Spatiale Imperial Francaise - Imperial French Space Navy|
|MSF||Marine Spatiale Francaise - French Republican Space Navy, the predecessor to the MSIF|
|PD||Point Defence - a weapon designed to protect a location or vehicle from incoming missiles or shells. Normally a rapid fire weapon tied to a detection system.|
The Pélican was designed as an interface vehicle likely to be encountered in both civilian and military colonial situations. The slew wing was chosen to give the science fiction feel of something that was unfamiliar to players but still believable.
The slew wing was first studied during WWII in a couple of German designs, the Blohm und Voss P202 which was a slew-wing and the Messerschmitt P1109, which had wings above and below the fuselage slewing in opposite directions (sometimes called a scissor-wing). NASA actually flew a subsonic slew wing prototype (AD-1 1979 - 1982) so the concept is firmly based in reality.
The statistics for the three models of Pélican were calculated using the GDW Star Cruiser Naval Architect's Manual.
For comparison a Pélican is slightly smaller than a Boeing 747 (which is 70.6m long with a 59.6m wingspan).
Copyright J.M. Pearson, 2003