been run on an engine to demonstrate a 10% flow increase.The choice for this study Condition 1 2 3 of a high temperature version of this engine rather than the basic olympus 593 Mach number 2.0 1.2 0,93 0.50 was dictated by a desire to meet a take-off thrust of around 50 000 1b within a reheat Altitude（ft) 53000 40000 25000 15000 temperature of 1800K. Assumed 0.9371 0.9858 0,99 0.99 The relative weights of these engines are intake PRF shown on Figure 4 as a function of flow increase over the Olympus 593.Also shown Net thrust 14610 19430 11980 9940 is the effect of scaling up the turbojets. (1bf) It will be seen that to increase flow by increasing bypass ratio is 'a considerably Relative lighter route than scaling up an engine. importance in 73,8% 10.3% 6.6% 9.2% mission fuel Condition 1:supersonic acceleration and 20n cruise Condition 2: transonic acceleration RESSED Condition 3: ENSINE diversion cruise WEICHT Condition 4:hold 乳A7ME 心Y 5 Table 4 Flight Conditions for Mission Fuel Calculation (ISA 50C) 卜/25 OWER L4WS4kE 4材-2口 1550 SOT LINE CONSISTENT WITH ⊙7九RET产 FI0 32 OF SAE 75/056 a格3 ▲my9pEs9is 10 5 20 25 30 COWEPALANT L 4s% 550K57 7龙LA/RFLOW RELA7e7DMMP然B93 15s0 元B2F4ND SOT Fig 4. Estimated Weight of Engines for ICAO Studies 2 It is of interest to compare the results of powerplant plus fuel weight calculations MEW DTZOM for the family of engines studied with the - -- results of earlier parametric studies such as Figure 3 which are based on simple cycle calculations and weight formulae. 2 OPERATINS CRUISE PYAASS RATO 05 格 The engines have been scaled to the common cruise thrust requirement of the Fig 5. Comparison of ICAO Study Engines 700 000 1b TOGW;4200 nm range,Mach 2.0 with Original Parametric Studies cruise aircraft model described in Reference 3.The internal engine perfor- Take-off and flyover noise estimates have mance was evaluated at the flight condi- been made for the family of engines by a tions listed in Table 4 to determine the Rolls-Royce method,The results are shown fuel weight for a typical mission. The for typical thrust levels on Figure 6 and relative importance of each flight condi- Figure 7 as a function of mass flow relative tion in determining mission fuel weight is to Olympus 593.Noteworthy is the diminish- also given in Table 4. ing return of increasing mass flow at the flyover condition.The actual noise scales The full line of Figure 5 shows the have been omitted,as this and other methods results of a parametric study similar to are being reviewed by the ICAO Working Group Figure 3 and in fact using identical noise sub-group,and it would be undesirable assumptions to Figure 32 of Reference 4, to pre-empt the conclusion of the sub-group. except that a 1600 K TET (1550K stator outlet temperature)has been used.The By combining Figures 6 and 7 with the individually plotted points show the mission calculation it is possible to results for the family of engines here relate powerplant plus fuel weight described.The datum is the current with total air flow and noise level,as Olympus 593 scaled to suit the new aircraft shown on Figure 8,Figure 8 also shows the model.It will be seen that the trends of benefit to be obtained from increasing the earlier parametric study are closely cruise TET beyond the Class II level to confirmed by the current more detailed 1700K together with an increase of around evaluation. 3%in HP spool rpm.This corresponds tobeen run on an engine to demonstrate a 10% flow increase. The choice for this study of a high temperature version of this engine rather than the basic Olympus 593 was dictated by a desire to meet a take-off thrust of around 500000 lb within a reheat temperature of 1800 K. - The relative weights of these engines are shown on Figure 4 as a function of flow increase over the Olympus 593. Also shown is the effect of scaling up the turbojets. It will be seen that to increase flow by increasing bypass ratio is a considerably lighter route than scaling up an engine. Fig 4. Estimated Weight of Engines for ICAO - Studies It is of interest to compare the results of powerplant plus fuel weight calculations for the family of engines studied with the results of earlier parametric studies such as Figure 3 which are based on simple cycle calculations and weight formulae. The engines have been scaled to the common cruise thrust requirement of the 700 000 lb TCGW; 4200 nm range, Mach 2.0 cruise aircraft model described in Reference 3. The internal engine,perfor- mance was evaluated at the flight condi￾tions listed in Table 4 to determine the fuel weight for a typical mission. The relative importance of each flight condi￾tion in determining mission fuel weight is also given in Table 4. The full line of Figure 5 shows the results of a parametric study similar to Figure 3 and in fact using identical assumptions to Figgre 32 of Reference 4, except that a 1600 K TET (155OoK stator outlet temperature) has been used. The individually plotted points show the ,results for the famil'y of engines here described. The datum is the current Olympus 593 scaled to suit the new aircraft model. It will be seen that the trends of the earlier parametric study are closely Eonfirmed by the current more detailed evaluation. J ~ Condition Mach number Altitude (ft) Assumed intake PRF Net thrust (lbf) Relative importance in mission fuel 73.8% 10.3% 6.6% ~ ILL 4 _____ 0.50 15 O( __ ~ 0.99 ~ 9940 ~ 9.2% .- Condition 1: sunersonic acceleration and cruise Condition 2: transonic acceleration Condition 3: diversion cruise Condi.tion 4: hold Table 4 - Fliqht Conditions for Mission Fuel Calculation (ISA + 50CL Fig 5. Comparison of ICAO Study Engines with Original Parametric Studies Take-off and flyover noise estimates have been made for the family of engines by a Rolls-Royce method. The results are shown for typical thrust levels on Figure 6 and Figure 7 as a function of mass flow relative to Olympus 593. Noteworthy is the diminish￾ing return of increasing mass flow at the flyover condition. The actual noise scales tiave been omitted, as this and other methods are being reviewed by the ICAO Working Group noise sub-group, and it would be undesirable to pre-empt the conclusion of the sub-group. By combining Figures 6 and 7 with the mission calculation it is possible tb relate powerplant plus fuel maight with total air flow and noise level, as shown on Figure 8. Figure 8 also .shows the benefit to be obtained from increasing cruise TET beyond the Class I1 level to 1700 K together with an increase of around 3% in, HP spool rpm. This corresponds to 5