The FRMP boom extensions fits on the end of your booms. By using different boom extensions you can mount motors of different types and sizes to your FRMP based craft. The extensions are made from 3mm Baltic birch plywood. Since the motors don't actually touch the aluminum boom, motor and prop vibrations are reduced. This is very important for a flying robotics platform.


Whats included with the FRMP Boom Extension kit?

A boom extension consists of 2 pieces. A top extension and a bottom extension. They are placed on the top and bottom at the and of the boom.

You can use, steel, aluminum, or nylon hardware. The boom extension sold in the on-line store has an option to purchase nylon hardware with your purchase.

Listed below is a list hardware required for each boom. If you are building a quad you will need 4X the quantity listed. For a Hex 6X

  • 5, 6-32 x 1" Machine screws

  • 5, #6 lock washers

  • 5, 6-32 hex nuts

  • 3, #6 x 1/2" spacers

You will need to provide your own motor mounting hardware which consists of 16, 4-40 x 1/2" machine screws and 16,4-40 nylock hex nuts.




If you plan on painting your extensions, you should do it now. Acrylic paint works best. Apply one coat, then let it dry. Sand it with 220 grit sand paper, then apply a second coat. This will give the extension an very smooth appearance.


Step 1

Using your motor mounting hardware attach your motor to the bottom extension as shown below. The bottom extension is the one without the larger hole. Be sure to orient your motor so that the wires are facing the direction where the boom will be placed. Insert the four 4-40 x 1/2" machine screws as shown.

KFE 28mm Boom Extension Assembly Step 1.jpg

Step 2

Secure the screws with four 4-40 nyloc hex nuts as shown.

KFE 28mm Boom Extension Assembly Step 2.jpg

Step 3

Slide the bottom extension under the end of the boom as shown below. Make sure the wires from the motor are inside the boom. Now is the time to attach the motor wire extenders if needed.

KFE 28mm Boom Extension Assembly Step 3.jpg

Step 4

Slip the top extension over the motor as shown below. The large opening should slip over the motor.

KFE 28mm Boom Extension Assembly Step 4.jpg

Step 5

Insert two of the 6-32 x 1" screws into the hole shown below. You may have to work them around the wires to reach the bottom hole in the boom.

KFE 28mm Boom Extension Assembly Step 5.jpg

Step 6

Slip three spacers between the top extension and bottom extension where the three holes are located as shown below. Insert three 5-32 x 1" machine screws into the holes as shown. You may have to nudge the location of the spacer so the screw will pass through it.

KFE 28mm Boom Extension Assembly Step 6.jpg

Step 7

Be sure the screws pass through the bottom extension as shown below.

KFE 28mm Boom Extension Assembly Step 7.jpg


Step 8

Add a lock washer and #6 hex nut to each of the exposed screws and tighten. If you are using nylon hardware, don't over tighten.

KFE 28mm Boom Extension Assembly Step 8.jpg


That completes the boom extension assembly. Run your wires the way normally would to connect your motors to your ESC.

KFE 28mm Boom Extension Assembly complete.jpg

As an option, you may mount the motor on the top of the boom as shown below. The assembly is the same except the top and bottom extensions are reversed. A hole in the bottom plate has been provided to pass the motor wires. (Note that the bottom plate is really the top plate in this instance)

While bottom mounting the motor may have a better look, top mounting the motor may be preferable as the boom provides less drag on the propeller. This means less prop noise and slightly longer flight times. There is also means less chance of the prop hitting the boom in the case of a mishap.

KFE 28mm Boom Extension Top Mount.jpg