Propeller Balancing

Welcome to the home of Precision on-site propeller balancing and vibration analysis for UAVs, drones, autonomous aircraft, both civilian and military This is where you can find the most precise, accurate analysis and balancing of your propeller/motor combination. We're a mobile service and will travel to your company or to an airport conveniently nearby. We're fully insured to work on UAV/drone power units and that is our specialty.Our technician's hands-on aviation technical experience spans 50 years and a range of aircraft from cold-war era jet fighters and bombers to modern airliners and general aviation (GA) piston aircraft. We no longer perform balancing on general aviation aircraft (Cessna, Piper, Beech etc). However, havng successfully balanced well over 600 of these GA aircraft, over a 14 year span, we have a wealth of knowledge about the intricacies and tricks and traps associated with both static and dynamic balancing. Unlike those regular aircraft, drones and UAVs are extremely challenging to balance because, for example during hover, the speed of each motor is constantly varying in order to maintain a level attitude.. It takes many runs to bring the imbalance of each UAV or drone motor and prop down to close to zero. It also takes many judgements by a skilled expert during these runs in order to get these propellers to be in balance throughout their wide speed range. So it's nothing like balancing a regular aircraft, where there is a steady cruise speed at which we need to have a smooth motor and prop. hovering UAVs, drones, autonomous aircraft need to be extremely smooth throughout a very wide range of speeds. That requires that the person doing the balancing be expert at tricking the assembly into complying. WHY IS IT SO DIFFICULT AND COMPLEX? Because vibration comes from a variety of sources and is difficult. but not impossible, to cure. Just looking at a mass imbalance, for example, when you apply a corrective weight to the propeller hub this weight is only good for a specific narrow range of RPMs. For example, putting a 12 gram weight somewhere on the hub might be the perfect amount to use at 2000 RPM but it could easily be too much or too little at a higher RPM. Also there will be not just one but several mass imbalances around the hub, each requiring a corrective weight. These can and will interact with each other to give you a situation that is very difficult to resolve - unless you've seen hundreds or thousands of these and have developed the skills to get around the laws of physics enough to make the propeller assembly useable for your purposes. First, however, the sources of vibration must be clearly identifed and each treated differently. Read on and find out why we're the best in the business!

How big a problem is vibration anyway?
Well, you probably have at least .4 ips of vibration occurring within your operating range - that's over 40lbs of oscillating force at the front bearing - Like a jackhammer ! Amazingly, most have even more vibration!
You need to get the vibration down to .2ips or below throughout the operating range in order to have a smooth platform for your avionics and other equipment on board.
What's causing your prop vibration? - mostly prop/spinner mass imbalance. The spinning prop has a resonant frequency and the motor has a different frequency - the spinner, hub or motor are often out of balance too. However, other things can come into play too - blade tracking errors, pitch divergence between the blades mounted in a hub, even aerodynamic interaction between blades on a hub. These will play hell with the balancing equipment's readings, fooling it into asking for weights to try to eliminate vibration that's not caused by mass imbalance at all, but perhaps by pitch or tracking errors. You can waste days, weeks, months trying to discover the cause and the cure for each of these - or you can call us to come to your facility and cure it for you - a wise choice. WHat about static balancing? Even if you carefully static balanced the propeller before installing it you will have serious vibration occurring somewhere in your hover or cruise speed range.: (A new prop is balanced at rest, on a set of parallel rails, not spin-balanced - there's a huge difference !) Static balancing cannot detect how the assembly will behave once it is spinning at high speed. Resonance plays a major role too - harmonic resonance of the blades, motor, mounting system and airframe can cause vibration spikes in various RPM ranges. Even if you've already tried having it dynamically balanced elsewhere or tried to do it in-house you will find that it's a very difficult problem to resolve and one that's vital to fix. It requires a set of special skills and experience that only someone with many years of experience can provide.Theoretical analysis won't work here - you need to have the assembly spun and the vibration diagnosed by someone with long practical experience. It can make the difference between success or failure of your project. When we Dynamically balance your propeller assemblies you'll see a BIG improvement ! We can completely eliminate vibration in most cases, or vastly reduce it. We can most certainly pinpoint the precise cause and give guidance to ensure that you can identify and eliminate manufacturing, mounting and procedural errors.
GIve your UAV, drone or autonomous aircraft project the very best chance to succeed
It typically takes about 4-6 hours of motor runs and adjustment per prop to get the best result.

Expert dynamic propeller palancing - it will make your project fly.

Call (831) 331-3660 or email for an appointment.

You'll see why we're the best in the business!

Please explore these links to see details of the tests and balancing:

Send mail to jeremym@spxdata.com with questions or comments about this web site.
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Last modified: April 04, 2018