Download - British Electric Flight Association

As accurately as possible, carve the foam to receive the Günther propeller so that
the back of the propeller is flush with the back of the spinner. Using the cone
shaped rotary stone attachment for the Dremel, lightly bore into the foam, keeping
everything as central as possible.
Now the clever bit. Cover the Graupner spinner with double sided tape and simply
press the foam spinner on, using the model's nose former as a square, flat guide.
You'll probably have to experiment a bit to get it right.
A small degree of eccentricity is not noticed in practice. There is no flight load on
it, the only force being the airstream pushing it on, which is to our advantage, and
the rotating mass is so low that there is no vibration, even at 13000 rpm.
One of the features of using the Günther propeller is that spinners tend look too
large in relation to the propeller, blocking out a seemingly high percentage of the
swept area. The small Günther propeller has a diameter of 125mm. Even if a
spinner were half that at 62.5mm, which is unlikely, it would blank out only 25%
of the swept area. Actual spinners required are typically less than 40mm, blocking
out less than 10% of the disc area.
More important is the effect a large nose diameter has on the airflow leaving the
back of the propeller, so it makes sense to reduce the nose diameter to the minimum
practicable. This can be achieved by utilising the full length of the Speed 400
shaft. About 30mm diameter spinners can then be fitted. These have a mere 6%
blanking effect. It is always good practice on an aeroplane, full size or model, to
reduce everything to the minimum that will do the job.
My Speed 400 Tucano incorporating all the above best practices, built light and
with an 8 cell KAN pack has a flying weight of just over 18 ozs. It goes like stink,
has good duration and amazes the IC mob. What price now brushless / LiPo !
So far going the 'grub screw adapter' route has proved completely satisfactory. I
keep two spare complete propeller/spinner assemblies in my flight box just in case.
Propellers can be quickly and easily changed in the field should one experience a
less-than-ideal landing, not that this has ever happened to me (honest).
46
E.F.-U.K.