Graupner,Luftschraube linksl.20x15 cm,1317.20.15L

Luftschraube linksl.20x15 cm Graupner 1317.20.15L SUPER NYLON propellers
Made of glass fibre reinforced nylon.
Highly efficient and tough. In neutral colour. For the selection of propellers approximate
values are indicated for each engine.

When used in conjunction with large and very powerful engines the ultimate load factor of SUPER NYLON propellers may be reached or even exceeded. In cases like these wooden pro-pellers should preferably be used. The rotational speed, that is the velocity of the airscrew tip in the plane of rotation, provides some information on the limiting factor. The rotational speed must not exceed 180 m/sec. Maximum airscrew rpmare then governed by the diameter of the propeller. Max. revolutions can be calculated using the following formula: Constant (includes safe value) 3438: diameter of prop (in meters). Taking a 28 cm diam. propeller the formula reads: 3438.0.28 = 12279 rpm. The actual ultimate load depends on several other factors in addition to rotational speed though, such as engine vibrations and propeller warping as a result of improper installation, to name but a few, which can affect theultimate load factor negatively. Propellers should be mounted perfectly centered on the prop shaft and with a minimum of play. If necessary install a propeller adapter of No. 198. In order to preserve the good physical properties of SUPER NYLON propellers, in particular their strength, their water contents of approx. 2 - 3% must stay trapped in the material. For that reason they should not be stored in dry rooms or near warm heating units. A lack of water contents can be compensated either by putting the propeller in boiling water for a short while or by submerging it in water at ambient temperature for a couple of days. Be sure to abide by the safety guidelines concerning
rotating propellers! Always remain clear of the propeller arc! Do not ever use a damaged propeller!

Ø 20 cm