SPINNER FAQ - READ THIS FIRST

Frequently Asked Questions

What is a Spinner in this context?
Electric glider fliers use the word Spinner to mean a fairing and a centre piece (yoke or hub) that holds the prop blades in a folding propeller. For non-e-gliders a spinner is just a rotating aerodynamic fairing to help the air flow smoothly.

The blades are held extended when the motor is running by centrifugal force and fold back against the glider fuselage when the motor stops due to aerodynamic drag. This significantly reduces drag and improves glide efficiency.

What are the parts of a Spinner?
Electric folding spinner assemblies usually consist of

• The spinner cone - the aerodynamic fairing, usually made from plastic or carbon fibre.
• The centre yoke (also called a hub) that holds the prop blades, usually made from aluminium.
• Hinge pins that the prop blades fold about. Usually 3mm diameter but 2mm in most 25mm spinners.
• Collet spinners also need a conical collet to interface the yoke to the motor or gearbox shaft.

What does the spinner product name mean?
Each part of the 30mm GM F5J Spinner (No Collet) product name means something:
30mm - the diameter of the plastic spinner cone.
GM - the manufacturer’s name or abbreviation.
F5J - optional, the intended application - large electric thermal soaring gliders in this case.
(No Collet) - this is a reminder that the collet is not included in the price and needs to be purchased separately, to match the motor or gearbox shaft.

Alternatively for spinners that attach using grub screws the spinner name may read 30mm VM Pro Spinner for 4mm shafts the for 4mm shafts indicates the size of the output shaft the yoke has been drilled for. This will need to match the shaft diameter of the motor or gearbox used.

How do I select the correct spinner?
The folding spinner interfaces the model, the motor, and the prop blades to each other so it has to match the size of each. This is why we need to stock so many different versions, to match all the parts.
1. Select the spinner diameter to match the size of the fuselage firewall. This is listed as "Spinner Diameter" in the specifications box for the models we sell.
2a. For a collet spinner add a collet to the basket to match the motor/gearbox shaft size, from the same manufacturer, as collets are not interchangeable.
2b. Or for grub screw spinners select the spinner with a hole to match the motor/gearbox shaft size.
3. Confirm that you can purchase (from HyperFlight or elsewhere) suitable diameter prop blades for the motor and number of battery cells to be used.
4. Confirm that the prop blades have a blade root width and hinge pin hole size that matches those of the spinner selected. This is usually 8mm blade root width and 3mm hole size for the 28mm and up spinners and 8"+ diameter prop blades. Pay close attention when using smaller spinners and prop blades as they mostly, but not universally use 5mm blade roots and 2mm hinge pins.

What are the rubber bands for?
Aerodynamic drag is usually enough push the prop blades flat against the fuselage but some modellers use small rubber bands from one blade to the other to ensure they close completely every time. These are usually not included in the product and need to be purchased separately.

What is a cranked hub?
It is the offsetting of the blades, when looked at from the front. For this reason some manufacturers call them Offset hubs or Z hubs.

What is the benefit of a cranked hub?
It helps the folded prop blades sit closer to the fuselage, reducing drag.

Does the cranked hub put any extra stress on the blades?
Yes, there is some evidence that the cranked nature of these spinners DOES increase the stress on the blades. To be on the safe side we recommend that the max safe RPM of the blades is reduced by 25% below the manufacturer's normal recommendation.

What folding prop blades are 8mm root width spinners compatible with?
They are compatible with the great majority of folding prop blades produced, including those by GM, CN, VM, Vitaprop, Aeronaut, Graupner, and RFM. The 8mm blade root and 3mm hole size are a standard that is used by prop blade manufacturers for most or all of their range.

Why don't the prop blades open fully?
Sometimes the plastic spinner cone stops the blade fully opening. This can happen because the blade root is thicker than usual, and it may cause the prop to vibrate or operate at lower efficiency. To allow the blades to fully open cut away the spinner cone with a sharp modelling knife, until the blades can swing freely. They should be able to open at least 90 degrees to the prop shaft.

How do I secure the spinner to the motor shaft
Sometimes the spinner keeps coming loose on the motor shaft, even though the Allen key grub screws have been tightened fully. In this case it is best to file or grind a "flat" on the motor shaft using a grinding wheel or good quality file. It is best if the flat does not extend all the way to the end of the shaft, so even if the grub screw comes a bit loose the spinner won't be able to come off. At HyperFlight we are not sure of the benefit of having two grub screws opposing each other, giving two points of contact. We think one grub screw may be better giving one point and one surface contact. Hence we only use one screw, and file one flat on the motor shaft. Keep the other grub screw as a spare.

What colour cone is supplied & available with Vladimir's Models spinners?
All spinners are supplied with black cones, not white as shown in many of the illustrations. Extra cones are available in yellow, red, and orange, to match the Vladimir's Models standard gel coat colours. Get them from the Spinner Accessories section.

What does the "Turbo" front hole do?
Tests have shown that a rotating spinner acts as a centrifugal pump, expelling all air at its periphery. We have heard of instances where a rotating spinner pulled air backwards though the fuselage, and out through the spinner gap. However the main benefit is when the motor has stopped, by letting pitot pressure air get into the fuselage, improving the flow of cooling air though the fuselage, as long as adequate exit vents have been installed. These should preferably be backward facing, in low pressure areas - not under the wing. Of course there must be suitable holes in the motor firewall for this to work.

I have another question, can you answer it?
Yes. Please use the contact form or email us.