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FAQ

Frequently Asked Questions:

1.    Do you have a soft motor mount for the YS110, ST2300, or <your favorite motor here>?

Sorry, we don't.  All of the motor mounts we currently offer are listed on the website.  During the Hey Day of glow power in Pattern flying we offered a mount for the YS line of 4-stroke motors, however, with the onset of electric power systems the demand for glow mounts disappeared and it wasn't economically viable to continue to have the metal mounting brackets fabricated (that, and the fact that my fab shop supplier closed a few years ago).  We do plan on developing an updated Soft Motor Mount for these, and other motors.  For the latest info look here.

An option is to adapt a conventional glass-filled or aluminum motor mount to the Soft Motor Mount Disk shown on our web site.  It wouldn’t be a difficult modification as there are attachment holes molded into the face of the disks plus there is ample space on the face of the disk to drill holes to match the nylon mount being adapted.  Also, the inside is easily accessible through the center holes in the fron and back of the nylon disks.

2.    Why do I have to use a nose ring with your soft motor mount?

The motor mount plate that the motor bolts to is not designed to handle the bending loads placed on it in the pitch axis by maneuvering flight loads when a nose ring is not used.  It was optimized for minimal weight and maximum stiffness in the torsional axis and will likely fail if used without some sort of mechanism to support the front end of the motor.

3.    At this point in time we’re having a handful of prototype supports fabricated domestically for testing to determine if the current concept is feasible.  We’ll keep you posted as to how it goes.

4.    I keep losing the little white plastic bushings for the Soft Motor Mount.  Where can I get some more?

Replacement bushings are now available on our website.

5.    Is a soft mount even needed for an electric powered pattern plane?

It depends on your priorities.  Granted the vibration environment created by an electric motor is much less hostile to the airframe and equipment than that created by a glow or ignition motor.  However, the electric motor/propeller combination does generate harmful vibration and transmits it into the airframe, just at frequencies and amplitudes that are not easily observed with the naked eye.  Our philosophy is that if we can provide an inexpensive, quality product that makes the task of mounting the motor easier, and effectively filters the vibration from the airframe, it’s a worthwhile improvement over “hard” mounting the motor.

6.    What’s the difference between the rubber bushings for the Standard vs. the Wide Electric Soft Motor Mount?

The soft bushings are ~10 durometer (about like warm bubble gum) and the firm bushings are ~55 durometer (more like a medium pencil eraser).  They both filter high frequency, low amplitude vibration well, the main difference being that the softer bushing has a lower cut-off frequency (the frequency were the signal attenuation, in this case vibration isolation, begins to become significant).

7.    Can I interchange the rubber bushings for the Standard and Wide Electric Soft Motor Mounts?

Yes, they are dimensionally identical.  While we supply the firm bushings as standard equipment with all of our mounts, the soft bushings may used for front mounted in-runner motors such as the Hacker C50 that use a rear support.<p>

The firmer bushings should be used when front mounting an out-runner (Hacker A50, Hacker A60, Axi 5330/F3A) and when aft mounting out-runners (Plettenberg Xtra 30-10, Axi 5330/F3A) to an aft firewall.  This is necessary to limit the amount of lateral displacement at the tip of the spinner during maneuvering flight loads to an acceptable amount.  We highly recommend the use of a rear motor support brace when front mounting an out-runner (with or without a soft mount) as the structural loads applied to the front of the fuselage without a rear motor support brace can be severe and may result in damage to, or failure of, the fuselage.

UPDATE  - The Hacker A60 motor does not fit the Standard width mounting plate (black), however it appears that the A50 does.  The Wide (gold) electric soft motor mount will fit both the Hacker A50 and Hacker A60 motors but check to be sure it will fit in your airplane if your spinner is smaller than 3.5" diameter.

The Axi 5330/F3A motor should be used with the Wide width mounting plate (gold) as it will not easily fit the Standard (purple) mounting plate.