Fuselage self-propulsion by static-pressure thrust - CAFE Foundation

Configuration
Integrated Conf. 00
Integrated Conf. 01
Integrated Conf . 02
Integrated Conf. 12
Body/Wake-Propeller 1
Bady/Wake-Propeller 2
Body/Jet-Propulsion A
Body/Jet-Propulsion B
Body/Jet-Propulsion C
Body/Jet-Propulsion D
Body/Jet-Propulsion E
Body/Jet-Propulsion F
Table V - Propulsion Evaluation Summary
=2rlO)
6
0.33
d/Y Lm-
0.147 0.0118
0.147 0.0115
0.147 0 0124
0.163 0.0150
0.351 0.0869
0.240 0.0415
0.0846 0.0115
0.0861 0.0124
0.0969 0.0150
0.147 0.0250
0.147 0.0260
0.163 0.0312
among aeronautical engineers, that the best that can
be done with axial pressure forces is to achieve near
zero pressure drag with unseparated concave aftbodies.
In this study, the integration of the radial pressure
17,20
distribution of the self-propelled Conf. 10
(transition tripped at 10% length) yielded a thrust of
0.0166; the agreement with the above 0.0168 is indeed
remarkable, as it demonstrates the nature of this
thrust force.
- C pt VjD0
0.970 0.674
0.965 0.669
1.05 0.715
1.044 0.690
1.10 0.961
1.18 0.987
4.17 2.043
4.53 2.129
4.13 2.033
2.18 1.479
2.36 1.536
2.24 1.497
-Pj G - CHPS_
0.52 0.0139
0.52 0.0128
0.54 0.0141
0.57 0.0182
0.175 0.0271
0.191 0.0318
-0.10 0.0417
-0.10 0.0500
"0.10 0.0537
"0.10 0.0337
-0.10 0.0404
"0.10 0.0443
Ips-
172.6%
187.5%
198.5%
170.3%
103.0%
88.0%
57.5%
55.9%
57.7%
71.0%
69.3%
69.9%
are below 0.2 and the body/jet-propulsor systems are In 1983 Goldschmied" presented the experimental
practically at the free-stream level, with values wind-tunnel evidence that the self-propelled freebelow
0.1.
transition models (Confs. 00 and 01) were in
It is quite evident that the integrated system equilibrium flight with jet total-head equal to free
presents propulsion characteristics which are far stream's and jet velocities less than 70% free
superior to, and radically different from, those of stream's. In this study integration of the radial
conventional systems.
pressure distributions seem to yield thrust much
greater than the computed skin-friction O.?lO; there
VI. Summarl:
can be no doubt that body self-propulsion has been
achieved by static-pressure thrust, with all the power
Thirty years ago the experimental wind-tunnel data applied to BLC and none to reaction thrust. This is
of Cerreta' demonstrated conclusively a 40% reduction indeed a significant milestone in applied aerodynamics
in "equivalent drag" (including BLC power) as against for General Aviation aircraft.
a streamlined body of equal volume, with transition A propulsive efficiency evaluation was also carried
tripped at 10% length on both bodies; this voided the out, on the basis of the conventional badylwakestill
popular "flat-plate syndrome" that substantial propeller and body/jet-thruster configurations; the
body drag reductions can only be achieved through efficiency index ranged from 88% to 103% and from 55%
laminar skin-friction.
to 70%, respectively. On the other hand, for the
The same Cerreta data also showed experimental self-propelled Goldschmied system the efficiency index
wake-drags as low as 0.0022, while the computed ranged from 172% to 198%; also it is well worth noting
turbulent skin-friction drag was 0.0190; clearly a that the mass flow required was only 15% of that for
body thrust force of 0.0168 had to occur to make this the best wake-propeller and 50% of that for the jethappen.
This voided another belief, still current thruster with equal jet diameter.
-18-
YII. Conclusions
In conclusion, since the fuselage represents at
least 50% of the total aircraft drag, fuselage self-
propulsion by static-pressure thrust should yield at
'W
least 25% total power reduction.
A preliminary design study by F. R. Goldschmied
(1984)" for 200 MPE cruise speed indicates a u