Difference between revisions of "How To - Set-Up a Pusher Style Folding Prop"

Revision as of 12:35, 4 June 2016

September 2015

Contents 1 Introduction 1.1 My Set-Ups 1.1.1 Prop Adapter 1.1.2 The Yoke 1.1.3 Blade Stop Plate 1.2 Options 1.3 Balancing 1.3.1 Make it Flat and Long 2 See Also 2.1 Vendors used for this project 2.2 Comments? Questions?
	Aeronaut!

Introduction

On a couple of the threads I enjoy on RCGroups, many people have asked how to set-up a folding prop in a pusher configuration. In my case I only use Aeronaut components because they are very high quality pieces and the complete prop assemblies are always easy to balance.

Here are two US vendors for Aeronaut parts seen on this page:

• Esprit Models
• Aloft Hobbies
  
  

If you are in Europe or can't find what you need at the above, these guys are great and have fast international shipping:

• Electric Wingman, UK
  
  

My Set-Ups

There are many ways to set up a folder using different components including a full spinner "in reverse". In my case I always use the same simple bare Aeronaut "Yoke" (which is the piece the blades are attached to). On my planes I have both shaft style motors and bolt on prop adapter style motors. Note: While I have seen some get successful results from a "reverse" spinner, I do NOT recommend it as it is difficult to set-up for vibration free running.

Here is an image with most of my setup components with a bolt-on prop adapter and alternate shaft style (set-screw) adapter:

Prop Adapter

If your motor uses a bolt on prop adapter you will need a reducer bushing to size it correctly for the Yoke mount hole. These bushings can be found online and one such vendor is GetFPV. Note: Make sure that if you don not use an Aeronaut yoke, you measure the ID of the center hole before buying the bushings.

Graupner Prop Reducers

If your motor has a shaft which requires a collet or grub screw style adapter, I recommend either Aeronaut or Scorpion brand and ONLY the type with the grub (set) screws. These are generally better in terms of straightness and machine quality. Here is the Aeronaut version. NOTE: The adapter must have an 8mm prop shaft to fit the Yoke.

Grub or Set Screw style prop adapter (Aeronaut)

The Yoke

On the Yoke, I use a 38mm size which is the distance between the blade attachment screws. Using a 38mm will guarantee the prop dimension is as-listed in terms of blade length.

Aeronaut Yoke

Another option I found while putting this page together is the Hacker Aluminium Hub for folding Props.

Shaft style Hub/Yoke from Hacker

These look very easy to set-up on a shaft style motor and because they are made by Hacker, should be fairly high quality. They show 43 sizes of this Yoke so finding one that fits should be a non issue. A 37mm x 8mm blade width x 6mm shaft size is listed for 12 Euro so the price isn't too bad especially considering it eliminates the need for a prop adapter!

The only place I have found them is directly from Hacker in Germany:

http://www.hacker-motor-shop.com/e-vendo.php?shop=hacker_e&a=article&ProdNr=19940100&t=10&c=4737&p=4737

Might be worth a try...

Blade Stop Plate

In a pusher set up it is important you use at least a rear stop plate to keep the blade tips from crossing. Normally, on a tractor set up, this is not required because the fuselage stops the blades from "over folding". If you don't include this simple piece, you stand the risk of having your motor-mount or plane shake itself apart.

Stop Plate

Although optional, I would also recommend using a front stop plate because on initial motor start-up the blades can over extend a bit and contact the fuse (in a wing) or horizontal stabilizers (V-tail). This generally results in big chunks of foam disappearing from your plane! The front stop plate should stop the blades slightly past center so that the blades are not actually contacting the stop plate at speed.

The stop plate can be made from thin plywood, carbon fiber or G10 fiberglass. It must be included in the assembly when balancing.

Another option is to 3D print these which has the added advantage of better clearance so you don't have to shave the prop blade hub down.

3D printed Stop Plate for the Aeronaut 38mm Yoke

To download a printable STL file of this 38mm stop plate, please click the link below:

Stop Plate 3D STL file

Options

1. A front stop plate is sometimes desirable if there is very little space between the prop and the airframe when fully extended. It is important to note that these should be trimmed so the blades can go past their natural extended position. Here is a picture of my FX-61 which shows a front stop plate installed.

FX-61 Set-up

2. Alternate Yokes with included collet shaft adapter - While these are available and easy to set-up, they very often cause issues with balancing and do not allow for the use of a front stop plate (if needed).

3. Reversed spinner - These also are readily available but can also present vibration issues as well as being heavy and more expensive.

Balancing

First of all, in my experience, Aeronaut props are impeccably made and I have always found them to be very close to perfectly balanced right out of the package. Having said that, balancing a folder can be challenging but there are a few tips which should make it easier and give good results.

I outline my balance method in another How-To, How To - Prop Balancing which is also the second part of my How-To on motor balancing. This section then follows that method but with the following additional preparation Tips.

Make it Flat and Long

• This means, make it like an ordinary fixed prop. To do this, tighten the blade screws just enough to hold the blades flat and straight.

• Next lay it flat on a table or bench so the hub (with stop plates if used) is flat on the surface and the blade tips are just touching the table top.

• With the prop in this position, use a plastic or wooden dowel and gently pry each blade out so it is firmly against the pivot screw in the outward direction. This removes the slack and very closely emulates where the blade will sit while spinning.

• Check that the hub is still flat with the blade tips touching then move the prop to the mag balancer and follow the process outlined in the Prop Balancing How-To.

Now go fly and enjoy a really nice prop upgrade!

See Also

RC Groups

How To - Motor Balancing

Vendors used for this project

Esprit Models

Get FPV

Comments? Questions?

email me!