Chapter 9: WhyHST (Y-Fuselage Hyper Sonic Transporter)

1. Illustration of WhyHST recently took-off under rocket power flying above an area with a volcano outpouring its lava viewed directly from above at night. 

All the conceptual designs in this book are modular, that is they can be further developed for extended applicabilities. WhyHST (Y-fuselage Hyper Sonic Transporter) resulted from a further development of WhySST concept (see WhySST). Basically a pair of rocket engines were added into the rear end of the twin fuselages of WhySST, a centerline MATSABU (Medium Altitude Trajectory Suborbital Auxiliary Booster Unit) is installed below the turbofans and the diamond wing was replaced with retractable canard and wing to produce WhyHST concept.

2. Top view of WhyHST with its wing and canard fully extended: This is the configuration during horizontal take off & landing. Notice also the pilots cockpit door, emergency cabin door and main cabin door along the centerline facing upward.

The canard and wing are fully extended during horizontal take off and landing only. WhyHST takes off using twin synchronized rocket engines. As they are significantly separated, but computer-synchronized, the significant separation actually provides stability similar to the stability effect caused by a long wheel based vehicle. The rocket-powered horizontal take off will be adequate in providing lift to WhyHST assisted by the extended canard and wing. As soon as the aircraft is lifted, its canard and wing are retracted into its fuselage to reduce drag as it begins its rocket-powered climb at a near-vertical angle toward its destination.

When an aircraft crash-landed on the ground, the least affected area is the fuselage rooftop. When an aircraft crash-landed in the sea, it may float and its fuselage rooftop may even stay above the water level. During reentry, the fuselage rooftop is also the least heated area.

3. When an aircraft crash-landed in the sea, it may float and its fuselage rooftop may even stay above the water level.

When a space shuttle reentry the Earth atmosphere at an angle, the fuselage rooftop is also the least heated area. WhyHST also perform similar reentry, but with least heating effect because unlike space shuttle that perform such procedure from orbit with very high velocity, this hypersonic aircraft only perform its reentry from a lower suborbital altitude with lower velocity.

4. The fuselage rooftop is the least heated area during reentry of a space shuttle.

Therefore, all the doors including the main cabin door and pilots cockpit door of WhyHST are located on the fuselage rooftop along its centerline. There is also an emergency cabin door between the 2 doors, and 2 more emergency exit doors on both sides of the rearmost seat row. The position of these doors increases the survival rate of the passengers in case of crash-landing on the ground or in the sea.

5. Top view of WhyHST with its wing and canard fully retracted: This is the configuration during the near-vertical rocket-powered climb.

6. Side view (top) & rear view (below) of WhyHST with their wing and canard fully extended: This is the configuration during horizontal take off & landing.

WhyHST can carry 100 passengers and 4 crews in a very comfortable seating inside its cabin excluding 2 pilots in a separated cabin, as the area between the 2 cabins is used for the storage of the retracted canard, rocket control system at upper deck and front landing gear at lower deck. The twin rocket engines are housed inside the rear end of both fuselages, and their propellant is housed in the storage between the passengers cabin and the 5 turbofans, which is also where the retracted wing is (the wing is sandwiched between the propellant tanks). 

7. Top view of WhyHST with its wing and canard fully retracted: The seats, canard, wing and rocket engines are made visible.

WhyHST climbs until its rocket propellant is depleted at 160km from sea level, but the momentum carries it to an apogee of 200km when the momentum and gravity is at an equilibrium. When reaching this apogee, all the passengers and crews are automatically entitled the "astronaut wings" because they reach space as defined by the 100km altitude, besides experiencing several minutes of microgravity. At this apogee too, the passengers will be able to clearly view the curvature of Earth with black space background. 

8. Bottom view of WhyHST: MATSABU is made visible.

Due to the gravity exceeding the momentum after apogee at the end of the microgravity period, WhyHST executes an "unpowered" reentry. From the start of the near-vertical rocket-powered climb until the end of reentry, the HST is in the hypersonic flight region (with a velocity of > Mach 5.0). During the initial reentry phase however, the HST is not totally unpowered, but its trajectory is maintained by the activation of MATSABU: Medium Altitude Trajectory Suborbital Auxiliary Booster Unit (auxiliary rocket to maintain reentry altitudes between 150km & 50km over a horizontal distance) to ensure it lands at a predetermined destination.

9. WhyHST typical 10,000km point-to-point suborbital flight profile.

WhyHST only ignites its turbofans when reaches 20km from sea level, and descends under the turbofan power supersonically until it reaches a subsonic velocity for conventional horizontal landing. Such flight profile will be able to allow the HST to reach a destination of 10,000km away in 2 hours.

As WhyHST lands conventional under turbofan power, it can land at an airport. However, rocket-powered take off may not be allowed at conventional airport (unless the airport is upgraded to a spaceport for rocket-powered take off), therefore to enable WhyHST to operate from an airport, it can be air-launched from a turbofan powered platform.

If the cabin size of WhyHST is reduced, carrying fewer number of passengers, and the propellant tanks for the rockets are added carrying more propellant for the rockets, WhyHST may reach higher altitude with greater momentum. This will allow the hypersonic aircraft to reach a further destination. And if the destination of 20,000km can be reached, WhyHST can perform an equatorial point-to-point suborbital flight from South East Asia to the Caribbean, maybe from Spaceport Malaysia to Spaceport Puerto Rico and vice versa.

10. An equatorial point-to-point suborbital flight profile from South East Asia to the Caribbean. 

Having the twin rockets at its sides rather than on its centerline enables WhyHST to be power-launched from above the fuselage of a single fin large universal carriers such as Airbus A380 or Boeing &747. Air launch, however will not affect the distance and flight time of the HST.

11. Illustration of WhyHST on top of Boeing 747: Notice the significantly separated WhyHST rockets that enable power-launch from the single-fin 747.

Of course the best carrier plane for WhyHST is Why1000 (see Why1000) because a Why1000 can carry a WhyHST inside its fuselage and safely drop-launch WhyHST. This point-to-point suborbital transportation system is described in a following chapter, "Why1000 & WhyHST Point-to-Point Suborbital Transportation System". 

DISCLAIMER

1. The background in figure 1 is from a public website.

2. Figure 3 is from a public website.

3. Figure 4 is from a public website.

4. Figure 10 is from a public website.

4. The Boeing 747 outline drawing in figure 11 is from a public website.

Chapter 8: WhySST (Super Sonic Transporter)

Chapter 10: No 335 CLT (Center Line Thrust) Light Aircraft

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