MODEL AEROPLANE NOTES and General Hobbicrafts

Auckland Star, Volume LXVIII, Issue 31, 6 February 1937, Page 3 (Supplement)

MODEL AEROPLANE NOTES and General Hobbicrafts

If you are an expert model aeroplane builder tlien the first portion of this article is not intended for von. I have lately noticed, from letters received, that there are a number of modellers who are very, very now to the game, and J would ask them to carefully follow the descriptions given below, and then they will have at once and for all the knowlodge of tin; names of the various parts. 1 hail a remarkable demonstration of this recently, when a boy asked me, -What is this dihedral angle you talk aluiuti" He had actually built three models, at that time. So get down to

thi! very beginning of things and get the names of the parts right to start Willi. Figure 1 illustrates the innke-up of thu average spar or stick-type model, and the key to tile various parts is now ° A—Propeller: Usually made from balsa wood. B—Collets or thrust washers: Aluminium, brass or copper. C—Propeller' bearing: Aluminium, brass or steel. D—Propeller shaft and front rubber" look combined: Steel wire. E—Can or centre rubber hoop: Wire. V— Rubber motor: Pure Jiigh grade para rubber strip. t; —>rain spar or motor stick: Balsa, hard grade. IX—Hoar rubber hook: Spring steel wire. I—Undercarriage: Wire or bamboo. J— Wheels: Aluminium, wood or eelK—Wing flips, holds wing to spar: Spring steel wire. L—Trailing edge of wing: Balsa. ll—Wing rib: Balsa. X—Main wing: Usually covered with ■tissue and doped. O—Wing tip: Balsa or bamboo. ■p —Elevator clip: Wire, not used much •in Xew Zealand. QO —Leading edge of main wing: Balsa. Q—Loading edge of elevator: Balsa. R—Elevator: Sometimes made of slieet balsa. S—Elevator rib: Balsa. T—Elevator tip: Balsa or bamboo. U—Leading edge of rudder: Balsa. V—Kudder: Covered with tissue. Sometimes made from sheet. W—Kudder clip: Wire. Xot used much in Xew Zealand. you will =cc from the above that balsa is miMtlv used, and as this very lightweight wood—the lightest in the world —is obtainable in many grades, the successful builder will select just the right kind for each separate job. A propeller should be good medium hard grade for an outdoor -bus," and the very softest grade for indoor machines. The main spar should be good and hard for the motor stick or spar, as this has to take a lot of tension from the wound up rubber. The sketch shown is very much like the 1337 Peanut I described some two mouths ago, and the Peanut, being a good beginner's model, ns well as a contest winner, would be a fair comparison to make: In a model like this with approximately 20in wing span, the propeller found most successful was Din diameter. The propeller shaft is 20 s.w.jr. spring steel wire, wlneli is iiist stion'' enough to take the strain (with perhaps a little to spare), and reduces the weight to the minimum requirements Xote that the rubber Im'k is turned in the wire lirst the wire mi-hcd through the propeller from the rear! cut to length, two right angte bonds turned in it. and then the end pushed back and cemented into the propeller bub. or centre portion It is most important that this shaft should face .the propeller exactly at right angles. Otherwise you will get a wobble on your propeller. io check Mn wind the propeller up a few' turns until the rubber draws fhe shatt m a

THE FIRST STEPS — KNOW YOUR MODEL. FOR THE BEGINNER.

straight line. Xow lot the propeller revolve a half turn, sighting the tip at some object in the distance. Let it revolve another half-turn and sec that the. other tip covers exactly the same place. Bend the shaft till it does this. Xow you have, it all right iTne way, but the' next thing is to see that it is vertically through the propeller, so sight a blade of the propeller from directly at right angles to the line of the motor stick. Calculate the approximate area of one blade, let the propeller revolve a half-turn and see that the other blade nppeiim no narrower or wider. All this can b<- avoided by drilling your first hole dead, true and sqiliire. ' As ?■'> per cent of the troubles [of a model lie around the making and

■fitting of the propeller, I am giving this important point plenty of explanation Xow conies the next item to watch The propeller bearing C must lean slightly forward, about 2deg being correct. Usually after winding up the model a few times, and perhaps hitting a tree or two. this propeller bearing "cts pushed back at the top, and thus lln* exactly the wrong effect. Look at"vour bearing, it must lean forward a little Look at it before every flight. The reason for this is that by so doing it will tilt the propeller slightly forward (it the top, and thus give what is known as "down thrust." Remember, "down thrust" is good. "Up thrust U the model-maker's worst enemy. Now for the collets, or thrust washers. If you get these with little burrs on them, file them off first. Then slip a pair over the propeller shaft so that the raised or pointed ends point to each other. This makes a smaller bearing

surface to rub. Oil the hearing and collets. Rough or unoiled collets and bearings nUsnrli a lot more power (hail the average liver realises. If you hear that •'squeak, squeak" coming from the propeller when the model is in flight, don't forget it is calling for oil urgently. Hometimes model livers use rubber lubricant for oiling, but.'a small can of oil should always be available. 1 would like to say 'right here that these instructions are not being given for fun only. They are fundamental principles which must be observed or you will never get. suncess I instance nil experience which I had just the other day. We had a meeting of the club and had invited some leaguers over to join in. These boys have been putting up some very fair IliEhts and have become fairly well acquainted with the building. They flew their models for an hour perhaps and wero getting only very poor results. Men seconds, sometimes, sometimes less. One machine was particularly well made, but it just wouldn't go. One of our more experienced members, "f! inner' Allen, walked over and had a look at one of the machines. It was n Cadet, quite well built, but putting up no sort of performance »t all. He looked at all the points , [ have mentioned above. Saw that the win" twist was right, and launched it. It . flew%tronglv for the first time and did . about 2.-. seconds. Not satisfied, he took the square end off the propeller, made :i : few more adjustments, and launched ii for a 40-sceoiid flight, and on a day. too. when it was blowing a howling gale. Xo magic used at all. Just, plain com- ■ moil sense and much experience to guide • him. And the other case was a similar I one. One of the other visitors had a ; small model somewhat like a Peanut. I which just would not go. Bill -Mackley

took it in hand, and in about live minutes had it (lying like a dream. 1 have heard since that the owner of this machine got two minutes out of it next day by himself. So delighted were these two boys that they went to the trouble of putting their appreciation in writing and sending it along to their very good friends who helped them.

To me tliis shows up two tilings. Firstly, half tlic flyers in New Zealand could easily <lmil)]e tlieir duration if they would look lit tlie finer points of flying; secondly, you fellows who are experts can make "things very much easier for the, younger members if you will give them a few minutes now and then. Jn most clubs, I am pleased to say, this spirit of co-operation and help exists to a great degree and there is little, if any, of"the hush-hush business indulged in. I find that the better the modellers are the more willing they are to tell others of the reasons of their success.

On Saturday, January 30, delegates from all over' Xcw Zen hi nil assembled in Auckland lo elect tlio ofliccrs and council of management of the Xew Zμhinil .Model Aeropliiiie Association. The following is the list, of oflice-bearers for the 1!):!7 season: — Patron: Tiis Excellency the fiovornorGcncral, Lonl (Jalway. President: Mr. K. Spencer Mason, Vice-presidents: Messrs. F. Wiseman, h. ]!. Hodge. IT. U. Parker, J. i". Mnckley, A. Y> Nicholson. Honorary secretary: Mr. W. G. Alexander.' Honorary treasurer: Mr. h. W. Parker. Honorary auditor: Mr. I. Watkin. Honorary solicitor: Mr. T. ("'. Webster. Honorary, recording ofllccr: Mr. K. (!. Kelson. Management council: Messrs. F, C. MacdonaWr' \V. 11. Maeklev, K. O. Mi-l.eod, W. U. OillesjMC. A technical advisory committee war. elected as follows: Messrs. W. ■'~ Mackley. V. 7i. Cray. L. R. Main, R. E. Allen. XI. ,J. Clark, '11. 1, , . Palmer.