Try both ways. Some model builders allow their propellers to get under way a second or so before the flight commences, and release them and push the machine forward at the same instant. One amateur secures his propellers by means of a thread which he breaks by touching it with a match, but it is rather fanciful.
What is the best height for a model aeroplane to fly?
In the principal model tournaments held in New York the models were seldom more than twenty feet from the ground at any time. Most model builders have this altitude in mind in designing their machines. It seems to be generally agreed that when a model rises higher than this too much power is used up in gaining altitude and there is a corresponding loss in the distance qualities. On the other hand in the remarkable 1,600 foot flight made by Cecil Peoli in July, the model rose to a height, it is believed, of more than 100 feet and gained considerable distance in gliding down. After all it is a problem which must be decided by the individual. Incidentally it is estimated that a large man-carrying aeroplane on rising to an altitude of one mile can safely soar with all power shut off for twelve miles. This means of course that an aviator has the choice of landing anywhere within a circle twenty-five miles in diameter, which gives him a rather wide choice.
What is meant by "critical soaring speed?"
It is claimed by some aviators that every aeroplane has a certain speed at which it flies best and beyond which it is unsafe to push it. If more power is put on, they argue, it will only tend to send the machine up in the air and will not increase its speed. This is probably true in a measure of model aeroplanes as well. When you have found the speed at which your aeroplane flies best do not change the number of rubber bands of your motor or the number of turns in winding.
Do the tails of birds serve as rudders to guide them in flying?
It is an open question. Some aviators who have made very careful observations of birds in flight deny that the tails have anything to do with their direction. The theory is advanced by some scientists that the birds used their heads to change their course, operating them as a forward rudder, much as do some types of aeroplanes. They argue that since a rudder is much more effective when placed forward the smaller surface presented by the flat heads and necks of birds has more effect than a comparatively large tail.
What is the relation of the wing surface to the weight and horse-power of the biplane as compared with the monoplane?
The Wright biplane carries a trifle more than two pounds of weight for each square foot of lifting surface. The Bleriot monoplane carries about five pounds weight to every square foot of lifting surface. On the other hand the Wright machine carries about forty pounds per horse-power, whereas the Bleriot will only carry about twenty-seven pounds. These figures do not work out for all biplanes or monoplanes but they indicate broadly the relation between the two general types of aeroplanes.
What would be the effect of bending down the outer ends of the wings of an aeroplane as the wings of some birds droop?