, Browns M.52 book as it relates to the XS-1 program is absolute rubbish, fiction in fact, so is the exchange of information he carries on about.Clark B. Millikan was the preeminent US aerodynamasist and this is report of his visit with Miles, note he wasn't given plans as is oft quoted.You'll also note his
There were UK engineers working with the US in the drop testing of XS-1 models, such was the relationship.
Technical Report of Visit by C. B. Millikan to
British M.A.P. Project E 24/43
Miles 52 Transonic Research Airplane
for distribution only to BuAir
Original 9 copies
Priority 1 'cuz Dr. Millikan is leaving for States 3 July
Summary
A technical description and assessment is given of a British project for a transonic research manned airplane. The project is sponsored by the Ministry of Aircraft Production, and is being designed and constructed by the Miles aircraft company. It is concluded that the design offers relatively little of interest to United States aircraft designers.
Introduction
On 28 June, 1945 a visit was made by Dr. C. B. Millikan, Technician, to the Miles aircraft factory at Reading. The purpose was an investigation of the transonic research airplane being developed by the Miles firm for the Ministry of Aircraft Production, through which agency the necessary clearances were arranged. Group Captain Banditt, R.A.F., the resident representative of M.A.P. at Miles was contacted upon arrival at the plant and served as guide during the entire visit which lasted some six hours. Mr. and Mrs. Miles entertained at lunch and conducted an extensive tour of the plant. Mr. Miles is president of the company and his wife, an extremely competent and active engineer, is understood to be in charge of structual design for all Miles aircraft. Neither, however, appeared to be much preoccupied with the details of the research airplane. Practically all of the information on the latter was obtained from Mr. Heal, the engineer in charge of the project, two of his engineering assistants who were called in, and Group Capt. Banditt who is closely following the development work.
On 29 June a visit was made to the R.A.E. at Farmborough where the development was further discussed with Mr. Smelt, in charge of flight research at the establishment, who is following the technical phases of the project. He furnished information on the power plant and the anticipated performance of the aircraft, and made it possible to draw certain inferences regarding the official M.A.P. view of the project. The latter are further discussed in Section 2 below, which the former are included in Sections 3 and 4.
2. General Description and Present Status of the Project
The airplane is being developed under a very general specification from the M.A.P. which specifies the power plant (an experimental Power - Jets unit) and calls for the production of an airplane to be used for flight research into the transonic range. No military or payload is required and the working out of detailed layout and aerodynamic specifications has, apparently, been left entirely to Miles. The design seems to be fairly fully worked out, a complete mock-up has been constructed, and a number of critical elements of the structure have been fabricated. The completion date is quite uncertain, February (1945/1946?) being mentioned as possible if priorities, etc. are pushed by M.A.P.
The Miles personnel were entirely ignorant of the many German developments which have recently come to light in connection with transonic aircraft and missiles, and neither they nor Group Capt. Barditt had apparently been informed of the existence of the German documents at ADI(K) nor of the fact that German workers in the field have been available in England for interrogation. It appears that the project has not been given a very high priority nor pushed very hard by M.A.P. It is, however, believed that following the present visit, Group Capt. Barditt proposes to take steps to increase the urgency with which the project is regarded. Group Capt. Banditt stated that the project was considered Top Secret, only four visitors have been shown it at Miles, and the present was the first approved visit by a non British subject.
3. Description of the Power Plant
Before proceeding to a discussion of the airframe it is desirable to describe the power plant which is being furnished by the government and around which the aircraft is to be built. The mock-up includes a quite detailed reproduction of the external of this unit which is currently under development by Power-Jets, Ltd, a government owned company formed to develop jet motors, especially those based on Whittle's work. The Miles engineers state that they have no first hand knowledge of the power plant development and that they have been informed that the figures given them are in many respects quite tentative and subject to later change.
The basic element of the power plant, which is called "Power-Jets: W2/700" is a direct development of the old Whittle turbojet which, in the U.S., led to the I-16. The W2/700 produces 2000 lb static thrust at sea level and seems to be much like an improved I-16 unit. This normal type of turbojet will be used to power the first version of the Miles 52 project which is not expected to reach the velocity of sound, except possibly in dives.
For the second version of the 52, (seems to be missing page 5 in the original at this juncture) which high speed exhaust gases are ejected through the nozzle at the end of the outer ring, just as are the exhaust gases from the prime mover which flow out through the tail pipe nozzle. In other words the Augmenter really is a second, very simple turbojet, with low compression ratio, in which the turbine drive power is taken from the "prime mover". The main purpose of the augmenter was stated to be increased thrust during take off. Apparently at high forward speeds the augmenter compression has little effect, the main compression coming from the ramjet effect. This explains a card on the mock-up which called the device an Athodyd and was at first quite puzzling.
Mr. Smelt indicated that the original conception of the Augmenter was that it should be a true, compressorless athodyd or ramjet taking air from the same plenum as the turbojet. At high speeds the Augmenter action is still essentially that of a ramjet. However it was found that the simple turbine-compressor wheel made it possible to obtain appreciable compression and considerable thrust from the Augmenter at low forward speeds without seriously interfering with the athodyd effect at high speeds.
The performance figures which had been furnished Miles for the complete power plant W2/700 with No. 4 Augmenter gave a thrust of approximately 3200 lbs under sea level static conditions and also at a flight velocity at 20,000 feet corresponding to M=1. It was emphasised however, the power plant is still definitely experimental and that the performance figures are likely to be changed.
4. Description of the Airframe
The accompanying free hand sketch, which is reproduced from memory, gives an idea of the general layout and overall dimensions. The most important numerical values were furnished by Mr. Heal and are given below:
Gross Weight - 8000 lbs (approx)
Total Fuel - 250 gal (probably kerosene)
Span - 27 ft Wing Area - 140 sq ft
Overall Length - 34 ft
Fuselage Diam - 5 ft (major portion cylindrical)
c.g. location 20 - 26% mean chord
Main Wing
Biconvex symetrical section with approximately 2:1 taper and surfaces formed by circular cylinders with constant (270 inch) radius of curvature throughout.
Root section max thickness/chord ratio - 7.5%
Tip " " " " " - 4%
Bending loads taken by wing skins which is very thick dural (approx 1/8 inch). Numerous stringers and ribs to retain shape and give stability. Bending loads transmitted to large fuselage ring girder through large forging of high strength alloy steel.
Zero sweepback of 50% chord line
Dihedral very small, if any.
Flaps, partial span, simple aileron type with piano hinge and no balance.
Leading and trailing edges finished to razor edge.
Clmax estimated at 0.8 to 0.9 without flaps and 1.3 with flaps.
Fuselage
Largely a circular cylinder 5 ft in diameter.
Air intake through annular duct surrounding the nose which contains the pilot in a sitting position, and the nose wheel well.
Nose section pressurised and jettisonable through the use of explosive bolts.
Nose and tail contours designed by Maccoll on basis of ballistic data.
Main landing gear wheels retracted into wells in the lower sides of the fuselage.
Fuel carried entirely in fuselage in annular tank close to C.G.
Control Surfaces and System
All tail surfaces are biconvex, symetrical sections each surface being a circular arc of constant radius.
Horizontal tail is all-moving without stabiliser. The sweepback indicated on the sketch was not done for drag reduction but to obtain the desired fore and aft location of the centre of pressure.
The hinge line appears to be 20% to 25% aft of the leading edge. Root thickness/chord ratio is 6.6%, tip is 4.4%
Rudder and ailerons are of the simple piano hinge, sealed type without aerodynamic or mass balance. Ailerons and flaps have approximately 25% of the wing chord.
All controls are operated through a hydraulic full power boost system which is completely irreversible. The operating cylinder is placed as close to the control surface as possible and all connecting links and bearings are extremely massive and rigid. This control system, which is intended to prevent flutter of the unbalanced controls has been very carefully worked out and an operating test system is in the plant. This was demonstrated and showed complete irreversibility and light control forces. The "feel" of the system will, be rather unusual however.
Design Load Factors
The airframe is designed on an ultimate strength basis for 8g below 20,000 ft and 10g above 20,000 ft. The strength specifications are apparently the only ones which were worked out in detail and set down in definite form.
5. Anticipated Performance
The airplane is supposed to take off unassisted, accelerate to best climbing speed, climb to its operating ceiling, make a 4 or 5 minute level flight or dive to obtain data, and return to the airport where it will land normally at some 150 mph. The contemplated duration of normal powered flight is accordingly some 15 to 20 minutes.
The first model without the power plant Augmenter will climb to something between 40,000 and 50,000 ft and should reach a level flight speed of a little over 0.8. During a controlled dive the RAE calculations indicate that it should reach a speed corresponding to just over M=1.0
The second model, with Augmenter has a calculated initial rate of climb of some 14,000 ft/min and an operating ceiling of a little over 60,000 ft. It's maximum level speed is estimated at about M=0.93 and during the dive from 60,000 ft approximately M=1.1 should be reached.
Since the take off and landing are quite conventional it is expected that a large number of test flights will be made, and that the speed near M=1 will be increased very gradually in successive flights. It is hoped that the powerful boost controls, relatively high design load factors, and very rigid construction will make such a program feasible.
Detailed performance calculations and aerodynamic studies are contained in a Farmborough Tech. Rep. No. Aero 1470, July 1944. This has R.A.E. reference number Aero 1344 R/F/96, is entitled "Further note on the Miles Supersonic aircraft (E 24/43)" and is by C.M.Fougère, B.A.
Conclusions and Recommendations
a) The project of a transonic research airplane is a valuable and interesting one.
b) The Miles aircraft for this purpose appears greatly handicapped by the power plant specified.
c) The Miles design was made without any knowledge of the recent German developments in the transonic field and accordingly has not taken advantage of much information which is now available.
d) The project seems not to be receiving very intensive support from the British government nor to have a very high urgency rating.
e) In general the design appears to have little to offer U.S. designers, although the very thin biconvex airfoil section with thick constant curvature covering, the unbalanced power boost control and the all moving tail might be of interest.
f) It is believed that with the present state of knowledge a much better solution of the transonic research airplane problem is possible.
In view of the above it is recommended that no further steps be taken by the Navy at this time to obtain additional information on the project from the British government.
Clark B. Millikan
Civilian Technician