Virgin Galactic unveils Mach 3 Transport Concept and its Analysis

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The new topic for My page : Optimization of Supersonic aerodynamic aircraft
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Boomsupersonic's XB-1

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Boomsupersonic Design

 There is an announcement from the Virgin Galactic (https://www.virgingalactic.com/articles/virgin-galactic-unveils-mach-3-aircraft-design-for-high-speed-travel-and-signs-memorandum-of-understanding-with-rolls-royce/); they signed memorandum of understanding with Rolls Royce for its power plant. 

 

 There are several transport project having more than Mach 1, Boomsupersonic, Aerionsupersonic, and now Virgin start their own project. Interestingly, each project targets different goal for its size and speed. 

 Boomsupersonic : Single-aisle Airliner (45 pax.) w/ Mach 2

 Aerionsupersonic : Business Jet w/ Mach 1.5

 Virgin Galactic : 9~19 pax. w/ Mach 3

 Similar to my analysis for other two projects, I try to figure out characteristics of Virgin's project. Because only three images are available, length of the contents is shorter than other projects having long history. 

 1) First Impression 

 Compare to other Mach 2 or 3 aircraft, it has minimal design; there is no movable wing like XB-70, or movable nose like T-4, or Concorde. Due to the effort of technological advance, vertical tail, main-wing, and inlet keep its shape and downward view can be replaced by periscope style camera from 21st century. 

 Overall impression is Mach 3 version of Boeing's Hypersonic concept while it has relatively large wing for its fuselage size and small vertical fin without any augmented ventral fin or other movable surfaces. Inlet conventionally uses two-dimensional shock compression and nose is split for upper and lower face connected to wing like stealth aircraft. 

 2) Nose

 Overall nose shape is like that of (probably imagine) SR-72. While simple circular nose made unwanted directional instability, elliptic or split nose can be helpful for directional stability. Also, that shape can exploit the canted angle for the pitch direction which generate pitch moment for certain condition to help trim. 

 Split line is smoothly connected to wing root, however size of the LERX is not big as jet fighter aircraft. Because this aircraft does not have any horizontal stabilizer, part generating positive pitching moment is restrained. Also, overall section of the nose become smaller as they reduce the shock-drag. 

 3) Wing

 As described above, wing is simple large delta wing without any complex combination. I expect that control surface is located near the root-end of the wing, and it is interesting to watch how they design the engine exhaust. Size of the wing can means they climb quickly than old-supersonic jet and accelerate at the given altitude. 

 Wing-tip is cut-off like F-15; effect of the cut-off is obvious to reduce the torsional moment or reduce the vortex. Leading-Edge of the wing is highlighted however, at this stage, I cannot make any speculation about this. Probably heat-reducing or flow control device can be located. 

 Fuselage of the aircraft is parallel for the engine pod at the underneath of the wing. Compare to other aircraft like Concorde, T-4, Tu-144, or SR-71, this arrangement is bizarre; except engine nacelle; lower surface of the those aircraft are smoothed. Only some Hypersonic wave-rider type aircraft is designed at that way. Control of interference of wave can be interesting.  

 4) Aft-Fuselage, Nacelle, and Tail

 Unfortunately, information from those images for the aft-fuselage, nacelle, and tail is very limited due to the angle of the view. Style of the vertical fin is very similar to that of Concorde, however, the fin is located at relatively forward position. Because supersonic flight requires stronger directional stability, those aircraft has enough control volume for the vertical fin. Non-conventional can be used to obtain the stability without unwanted-drag. 

 5) Conclusion

 Frankly, there is not much information from the three images, and also this concept art can be changed any time in design-refining-process. However, I just want to observe the images and guess interesting point which designers intended.