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Aviation History
1909
1909 - 0733.PDF
NOVEMBER 13, 1909. sides or ends of the compartment, the edges of the connecting-rod slots being slightly turned up. In any case over lubrication could not well cause a deposit, as, with valves in the cylinder-head, the cylinder would be self securing. Neither could a broken valve fall into the cylinder. Most of these points would also apply to V engines, f I may add that this idea was included in the design of a novel aeroplane, which circumstances have prevented my constructing, and in offering the suggestion I venture to predict that the first producer of an inverted aero motor will have many imitators. Yours faithfully, ' — --'•'• HOLTEC. AN AMATEUR-BUILT MODEL CLASS WANTED. To the Editor of FLIGHT. SIR,—Kindlv allow me through your valuable paper to draw atten- tion to the model flying competitions in several parts of the country. Being interested in moiel making and flying, I took the opportunity of visiting a model competition held at Woolton, near Liverpool, on October 30th, and to my sorrow I noticed that the prizes went to models made by large manufacturing firms. Now I think the ma-ority of your readers will agree with me when I say that if bought models are going to win all the prizes, it is going to take all" interest out of private model making for competition, for what person will spend his time and waste his brains making a model when he knows that he can purchase a guaranteed flyer for a few shillings ? So my opinion is that the sooner the aero clubs and societies throughout the country are brought to see it in this light the better it will be to the interest and advancement of the new science of aviation. Yours respectfully, Bootle, Lanes. P. MCKEOWN. TERMS IN FLIGHT. To the Editor of FLIGHT. SIR,—Allow me to suggest that the word "deck" should never be allowed to substitute the word " plane." Plane is by far the most suitable word for the supporting surface of an aeroplane. Any complexture from the word " plane " should be stamped out forthwith, especially the word "deck," asnodoubt before long flying machines will possess " real decks" for the convenience of passengers, although it may be advisable in the first place to allow a certain amount of swinging movement, so that the centre of gravity is in no way interfered with. I agree with everything your correspondent, Mr. Hammond, puts forward, and the way in which he sticks to common-sense. Regard- ing your correspondent, "Nil Desperandum," 1 greatly admire his pluck and enterprise in undertaking to produce complete working drawings of the extremely light and apparently efficient engine, but I think it would be more satisfactory for him if he went further in the matter, and produced a working model. The English financier is to-day a long way off his Continental rival so far as speculation is concerned ; in fact, he leaves much to be desired. I have had my experience in the matter, and I should suggest that " Nil Des- perandum " regards twelve months' waiting with equanimity. With an apology for the length of the epistle, Yours very sincerely, G. H. BROWN-EKINS. PROPELLERS. To the Editor of FLIGHT. SIR,—Answering Mr. H. G. Dawson's query in a recent issue, it must be stated that no figure for thrust per h.p. can be given unless the pitch and speed of rotation of the perfect propeller in question are known. This becomes clear when we consider that thrust is a force measured in lbs., whilst h.p. denotes a certain rate of doing work, and contains not only the factor of force, but those of distance and time as well. Let us assume a perfect propeller having a pitch of P feet, and revolving at a speed of N revs, per minute. Let T be the thrust in lbs. and let F"be the velocity of advance through the air in feet per minute (assuming the propeller to be driving an aeroplane). Since the propeller is perfect, i.e., of 100 per cent, efficiency, we T x Vhave h.p. input — h.p. output (useful) ; but h.p. output = —— (as 1-h.p. = 33,000 ft. lbs. per min.). As the slip is zero, we T P Nhave V= P x N ; therefore h.p. input = ; or thrust H H 33oo 33,000 33.ooo This result indicates that for propellers of different diameters, but having the same speed and pitch, the thrust per h.p. is the same. For example, propellers of 3 ft. pitch, revolving at 1,200 r.p.m. would, if perfect, give a thrust per h.p. of ' = 9"2 lbs. "X X I 20O Yours faithfully, ;: ••' ;-••• :':•:,?:*-:-•.'..;•'. '£.:••'- • :S-::~-: - R. C. CLINKER. To the Editor of FLIGHT. SIR,—I reply to Mr. H. G. Dawson's letter in a recent issue. He inquires for the utmost thrust per horse-power for a perfect propeller. As I have been engaged in the manufacture of pro- pellers for both marine and aerial work for upwards of fifteen years, I must tell him that, so far, there is no " perfect propeller." I experimented with a 4-foot propeller some time ago, and got a thrust of 4 lbs. per square foot at 1,000 revolutions. Now taking this in relation to the lift it works out 12 to 1. However, Sir Hiram Maxim gives (I think it was a lecture at the Mechanical Institute) a propeller would give a thrust of 5 lbs. per square foot, which would still reduce the ratio. In practical work I do not think there has been enough con- sideration given to the propellers. I do not mind making public the method I adopt. I leave the propeller to the last. After the model has been mide, I find its weight. I then procure the weight of the different sized engines, say a 20-h.p., weight 112 lbs., com- ponents, including patrol tank with 4 gallons of spirits, no lbs. Now take the total weight of machine (allowing for pilot's weight and approximate weight of aluminium propeller), and calcul tte the area of the propeller, running at a specified speed, necessary to drive this weight through the air at 10 miles per hour. On making the propeller allow a margin of 10 per cent, or upwards. A machine when travelling decreases its weight at a square of its increased speed, so that the 10 per cent, marginal increase of area must be increased in proportion, not forgetting the utmost power that the engine will give at the necessary speed. Trusting this will give Mr. Dawson and others an idea of the importance of the propeller's work, and wishing FLIGHT an ever increasing success, I am, yours faithfully, Chiswick. ' CECIL P. LEVERMORE. "AVIATION." To the Editor of FLIGHT. As this word is now universally in use, and as it is not a dictionary word, it might be interesting to investigate its origin, and to know who may claim to have first employed it in connection with aerial locomotion. I believe I am the originator, and although the word is euphonious, I long since learnt that it is quite incorrect if intended to mean "flying." Properly speaking, " aviation " means " bird- ing," " aviator" means " birder," " aviate " means " to bird." I think it would be more correct if the Press and public generally would use the words "volitate," meaning to fly; "volitator," a person who flies ; and " volitation," the act of flying. The words are quite as euphonious, and, in fact, more so, especially when using the corresponding expressions as they should be in the French language, viz :—" Voler" to fly ; " volitateur," a person who flies ; " volitation" the act of flying. Believe me, yours truly, Aero Club. GYROPTER." AN IRISHMAN—AND BRITISHER, / To the. Editor of FLIGHT. SIR,—Is it not a fact that Mr. J. T. C. Moore-Brabazon is an Irishman, and if this is the case why not state it, at least in as pro- minent a place as the notice about him in your issue of November 6th, 1909? Not wishing to incur Editorial condemnation as a self- advertiser, I subscribe myself, Yours faithfully. IRISHMAN. [Mr. Moore-Brahazon's Irish descent is so well-known that that must be our excuse for the obvious omission of the statement from our " history " last week. We can assure our correspondent, who, by the way, is a much esteemed motorist, that there was no intention on our part of doing an injustice to Ireland.—El).] To the Editor of FLIGHT. SIR,—In the current number of FLIGHT you refer to Mr. Moore- Brabazon as " the first Englishman to fly in a heavier-than-air machine." Over here we call him an Irishman, and I think you will find we are right. Yours faithfully, Castlerea, co. Roscommon. MAURICE J. DODD. 735
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