FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1944
1944 - 1554.PDF
104 FLIGHT JULY 27TH, 1944 CORRESPONDENCE to the Junkers Jumo 720 h.p. engine of 2 lb./h.p. which Germany is now fitting to their gian.t Blohm and Voss flying bo,ti of six engines (see Flight, May 4th.) Again, flying-boat construction does away with undercar riage complications and weight. It is obvious, I think, from these few remarks, that a very economical machine can be constructed for commercial pur poses if the diesel engine were available in this country. Why .should it not be available, and who has condemned it? It was being built by Napiers in this country before the war. It is the ideal engine tor long-distance work and ease of ser vicing, besides being more reliable. Tlie economical machine should also cruise at about 175 m.p.h. with a landing speed of about 65 m.p.h. for safety. Extremely high speeds are not desirable or wanted by the public; only by schoolboys. If airline companies were to copy the railway companies' organisation and system of drawing up a specification of the aircraft they require for commercial and economic purposes, for the manufacturer to comply with and tender for, they would then get a machine of minimum complications and maximum economy all round. On the other hand, if design is left entirely to the manufac turer he will naturally make the machine as expensive and complicated as possible so that he. will have a good demand for spares and' whack up a big initial price, which, after alt, is only business and human nature. Railway companies always design their own locomotives and rolling stock, and in some cases do their own manufac ture, which they find more convenient and economical! J. R. GOULD (Maj.). ANGLES OF BANK Mathematical Demonstration I N reply to your correspondent " Bankrupt," I think his problem can easily be explained as follows :— Let L poundals be lift. W poundals be weight. v ft./sec. be speed. r ft. be radius of turn. w rad/sec. be rate of turn. 6 be angle of bank. Then L cos 0 W W J'2 and L sin 6 = • w . „ cos 8 / :. tan 6 = w ,s- V- 1 S 1 ^ r v- w . — since r - f! V - _1 V w i.e., for a definite speed and rate of turn there is a definite angle of bank irrespective of the weight or wing loading of the aircraft^ Of course the aircraft of higher wing loading would fly at tbfT greater angle of attack. Incidentally I have, taken w as the true rate of turn about a vertical axis, not the indicated rate of turn (about an axis perpendicular to the plane of the aircraft). If w' is the indicated rate of turn :— ^ = w cos 6 cos 8 sinS ,(ii) w It will be seen that our deduction from (i) still applies to (ii). Hoping this is clear, Yours truly, ZEROX. — and Again ^ITH reference to the question asked by " Bankrupt " in the July 13th issue of Flight, the following is the simple theory which may help him. When an aircraft is turning there must be a centripetal force acting on the aircraft, i.e. a force towards the centre of the turning circle, equal and opposite to the centrifugal force. In order that there shall be no sideslip, the aircraft is banked until the hori zontal lift component is equal to the centrifugal V / L force. From diagram. • L Let F = centrifugal WV2 force= .^_ gr ~ W L = lift on wings. W = weight of aircraft. WVa Resolve Horiz : = L sin Resolve Vert : W = L cos 9 dividing (1) by (2) we have :— Which proves that for a given speed and radius of turn, the ingle 6 is constant. It will be seen from the diagram that if the angle of bank is too small then the horizontal lift component is insufficient and the aircraft will sideslip outwards. Similarly if the angle of bank is too great, then the aircraft will sideslip inwards. A point worth noting in passing is that, while turning t| outer wing is moving faster than the inner one, and thereto has a greater lift. Therefore there is a turning moment tending to overbank the plane due to the difference of the lift on each wing. Hence, when the turn has been completed, it is necessary to reverse the ailerons, which is known as " holding off " the bank. E. AUBREY. These two letters on Angles of Bank are representative of a large number received dealing with the same subject. NORMANDY BEACHHEAD MORS PEACEFUL THAN SOUTHERN ENGLAND T HE anti-aircraft barrage over the beaches in Normandy is so intense that German aircraft get nowhere near them during the day," said Col. Walter B. Goodrich, U.S. Army anti-aircraft expert, who for three weeks has been studying the beach barrage for the U.S. War Department Observation Board. "It's more peaceful there than right now in London and Southern England," he told Reuter's Special Correspondent. " We have an astounding number of guns over there." Over 100 German aircraft have been shot down, mostly at night, by the American beach barrage, which is so fierce that it is calculated that for each aircraft destroyed 800 rounds are tired by the heavier guns and 20,000 by machine guns. The first American anti-aircraft units landed on their beaches a few minutes after the first assault troops had gone in. They wire faced with heavy fire, but the air cover was so excellent that, in the early stages, their guns were used as field artillery to assist the consolidation of the beachhead. Col. Goodrich said that co-operation with the Allied fighters both day and night was first-class. "It is largely due to the wonderful team work between the Air Force and the anti- drcraft that the Luftwaffe has been kept away." During the first month of the invasion Allied aircraft losses totalled 1,284 aircraft. The Germans lost 1,067, excluding those destroyed or damaged on the ground. Although Allied losses are higher, the percentage in relation to sorties is extremely low, and it was stated at SHAEF that the German percentage must be "much higher," though it is impossible to be precise. I11 approximately 158,000 sorties from Britain and the Nor mandy airfields embodying operational missions of all types- tactical support of the battle, strategic attacks on industries in Germany and German occupied Europe, and defensive patrols and reconnaissance—just over 0.8 per cent, of Allied aircraft were lost. The percentage figure has actually decreased gradually since the initial phase, when it slightly exceeded 1 per cent. There is nothing surprising about the lowness of Allied losses in relation to the sorties flown. It is merely convincing proof of the overwhelming Allied superiority in the air. Detailed figures for the different air commands are as follow : U.S. Ninth Air Force: 38,000 sorties, 207 claims, 317 losses. R.A.F. Second T.A.F.: 36,000 sorties, 245 claims, 269 losses. A.D.G.R.: 2r,000 sorties, 134 claims, 49 losses. R.A.F. Bomber Command: 10,500 sorties, 109 claims, 216 losses. . i. U.S. Eighth Air Force: Heavy bombers: 27,500 sorties, j?' claims, 218 losses. U.S. Eighth Air Force: Fighters: 25,500 sorties, 317 claims, 215 losses.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
