Feasibility study of a supersonic business jet based on the Learjet airframe

Abstract

Since the dawn of the jet age, passengers on all jet transports, except Concorde, have traveled at about the same speed — a standard Mach 0 83-0 87 range as a practical compromise. After 27 years of supersonic commercial travel, British Airways and Air France retired their fleet of Concorde aircraft at the end of 2003 because it was considered no longer profitable. Clearly, with the retirement of Concorde, the world has lost the only aircraft offering passenger transportation at supersonic speeds. Over the past several years manufacturers have proposed new aircraft designs that promise an increase in transportation speeds. In particular, the business jet market appears to present a business case for an exclusive supersonic business jet (SSBJ). However, there is a key-hurdle which has, until now, prevented the successful launch of a SSBJ hardware program: the development cost for an all-new aircraft quickly eradicates the soughtafter business case. This paper presents the results of a parametric sizing study which aims to answer the following question: is it possible to drastically reduce the development effort of a supersonic business jet design by converting an existing Learjet airframe into a supersonic vehicle while sustaining FAA interest and approval? This paper discusses selected aircraft sizing trades and operations related constraints. The feasibility study indicates some level of technical plausibility for the case of converting an existing airframe into a certifiable lower-cost supersonic aircraft. Acknowledging the range of actual complications related to the task of economically modifying and certifying a legacy airframe towards a SSBJ, it appears that a larger size SSBJ offers significant technical and economical advantages which outweigh the ‘off-the-shelf’ Learjet case.

Conceptual aerodynamic design of an executive supersonic passenger aircraft – ESPA

“…Our initial calculations suggested a more conservative approach with values of 0.028, 0.032 and 0.042 being utilized; however, ultimately, our subsequent drag study suggests that 0.011 is a reasonable zero-lift drag estimation. This value is conservative compared to other SST designs of 0.0785 29 and 0.011 to 0.016. 14…”

“…An example of this approach, applied to a supersonic business jet using a reference design, is by Chudoba and Coleman. 29 Ferretto and Fusaro 30 argue the single matching chart approach is not viable for supersonic or hypersonic aircraft as it must also be optimized for the transitory mission speeds, altitudes and engine states and types they pass through. Ferretto and Fusaro 30 create instead a formulaic parameterization approach based on multiple matching charts (MMCs), where the individual and collective trade-offs and viability can be visualized.…”

“…Banerjee 33 supports a C Lmax closer to 1.5 as more appropriate for an SST at takeoff. Mathieu and Marin 14 were more conservative at 1.0, while Chudoba and Coleman 29 ( p . 39) are comparable in four configurations (1.26–1.78) ( p .…”

“…At 60,000 ft, the required thrust per unit weight to reach Mach 3 may be beyond our engine capacity. It is suggested in Banerjee 33 a C Do figure as low as 0.011 for a new supersonic cruise aircraft, with Chudoba and Coleman 29 highlighting the importance of slenderness for this estimate (p. 523). Our initial calculations suggested a more conservative approach with values of 0.028, 0.032 and 0.042 being utilized; however, ultimately, our subsequent drag study suggests that 0.011 is a reasonable zero-lift drag estimation.…”

“…At 60,000 ft, the required thrust per unit weight to reach Mach 3 may be beyond our engine capacity. It is suggested in Banerjee 33 a C Do figure as low as 0.011 for a new supersonic cruise aircraft, with Chudoba and Coleman 29 highlighting the importance of slenderness for this estimate ( p . 523).…”