Thrust Bearing Use For Quadcopter Drone Propeller Assembly And Air Bearings For Inner Motor Assembly

Should we be using different bearings for our high-speed rotor blades which are used on the most common drone types like the Quadcopter designs? I believe so, as these drones need to be very reliable, long range, and will have important cargo onboard as part of their important missions whether on the battlefield, commercial application or delivering you a very important pizza or Amazon package.

Not long ago, I was listening to an interesting NASA podcast on rotorcraft air bearings and foil bearings:

NASA Aeronautics Research Technical Seminar Podcast Series:

“Technical Seminar 16: Oil-Free Turbomachinery Technology for Rotorcraft Propulsion and Advanced Aerospace Propulsion and Power 1:14:33 11/24/2008. Oil-Free Turbomachinery Technology for Rotorcraft Propulsion and Advanced Aerospace Propulsion and Power”

This got me thinking that not only is this relevant to today’s military aircraft, space flight propulsion, future jet engines, but also relevant for high-speed little motors that spin well over 10,000 RPM. If we want these motors to last and if there are multiple motors per flying craft; MAV – Micro Air Vehicle, UAS – Unmanned Aerial System, or PFC – Personal Flying Craft (Air Taxi) then it makes sense to use such technology.

You see, I was thinking that it would sure be nice to lighten-up the motors on such future VTOL (vertical take-off and landing) aircraft concept designs since there are often 3-4 motors or more. Some of the benefits are very apropos:

1.) Nearly Maintenance Free Bearing Assembly

2.) Reduced Weight

3.) More even friction heat

This is a very good thing due to the geometry and weight distribution that Quadcopters have. Lower weight means more payload, less fuel and/or longer range.

Perhaps the weight savings of lube oil, (2-types needed in normal current helicopter technology) on each of the four motors could also give weight space for electromagnetic bearings with a thrust bearing combination around the outer ring on the rotorblades to control vibration and free-wheel free of drag, and easy start. If the motors happen to be electric, even better in this case. If high speed gas turbines we save weight and add safety to a nearly maintenance free design.

Some of the NASA tests have concluded 60,000 hours with no damage or need to replace parts or bearings. For a rotorcraft this is nearly unheard of due to the harsh environment they fly and the fact that the motors are under so significant load all the time the aircraft is airborne.

Now then, for the outer assembly – more safety is garnered by outer bearings, but reduced friction is the key, thus, electromagnetic system makes sense, but due to weight perhaps not 100% magnetic. This article explains the concept of Thrust Bearings and the combinations I propose we employ.

“Design, Fabrication, and Performance of Foil Gas Thrust Bearings for Microturbomachinery Applications,” by Brian Dykas, Robert Bruckner, Christopher DellaCorte, Brian Edmonds, and Joseph Prahl. (NASA/TM-2008-215062, January 2008; GT2008-50377).

Currently, we know that the quadcopter design is probably one of the most stable designs yet, but most quadcopters are only toys, small drones, and have a limited payload. If we want these types of designs to fly around people, heavy weight, or become our future flying cars and air taxis, commuter shuttles, we’ll need near 100% safety, that means current rotorcraft components may not be viable. Please think about the future, maybe you can have a flying car after all?

*Additional Cites to Consider When Evaluating This Concept:

A.) “Preliminary Analysis for an Optimized Oil-Free Rotorcraft Engine Concept,” by Samuel A. Howard, Robert J. Bruckner, Christopher, Kevin C. Radil. (NASA/TM-2008-215064 March 2008; ARL-TR-4398).

B.) “Tribology: Principles and Design Applications,” by R. D. Arnell, P. B. Davies, J. Halling, T. L. Whomes.

C.) “Measurements of Drag Torque, Lift-Off Journal Speed and Temperature in a Metal Mesh Foil Bearing,” by Luis San Andres, T. A. Chirathadam, Keun Ryu, and Tae Ho Kim (J. Eng. Gas Turbines Power 132(11), 112503 (Aug 11, 2010) (7 pages)doi:10.1115/1.4000863).

D.) “Thermohydrodynamic Model Predictions and Performance Measurements of Bump-Type Foil Bearing for Oil-Free Turboshaft Engines in Rotorcraft Propulsion Systems,” by Tae Ho Kim and Luis San Andres. (J. Tribol 132(1), 011701 (Nov 11, 2009) (11 pages)doi:10.1115/1.4000279).

E.) “Foil Bearing Starting Considerations and Requirements for Rotorcraft Engine Applications,” by K. C. Radil (Army Research Lab) and C. Della Corte (NASA). August 2009, Doc # 201200112857, (ARL-TR-4873, E-18263).

Drone Aerial Photography

The addition of cameras to drones may have just changed the way many industries run forever. They can be used to check areas that were previously impossible to see such as piping when checking safety and security, they can be used to keep control of policing situations such as riots and protests and they are even used in movies. Look out for it next time you watch a film, normally the video will start in the air like a plane and then move across giving the viewer a wonderful aerial shot that will be remembered.

Most drones that are available nowadays come with a built-in camera and a high quality one at that. If you own an old quadrotor and are looking to attach a camera of your own then a ‘GoPro’ camera is a good option however, you do have to consider the vibrations of the drone as this will affect the quality of the pictures that you take as well as the videos that you shoot. Built-in cameras offer a much more reliable quality consistently. Before shooting your first video you may also want to invest in a transmitter that will allow you to increase the range of connectivity when flying as well as broadcast video live from your drone.

You may look at some pictures that have been taken on a drone and compare them to yours and wonder how in earth theirs look so good yet yours barely classify as a picture. Here are some tips to remember when taking pictures or shooting videos from your drone!

Firstly, your camera is likely to get knocked around by the wind whilst in the air so make sure you are using a shorter lens to counteract this. If you couple a short lens with a fast shutter speed, you are likely to see dramatic improvements in your photography right away. A good rule of thumb to receive top quality is around 1/1000 second at 200mm and 1/500 second at 100mm. These combinations will allow you to take sharp, crisp photos no matter what conditions.

Another great tip when taking pictures from your drone is to set your camera to high contrast if haze becomes a problem (which it often does). If the problem is really bad to the point where you are getting black and white video, you may also want to shoot with a red filter. Normally, using any sort of filters such as ‘UV’ and ‘Haze’ tends to worsen the picture quality when in the air but the red filter will help to add colour.

Of course, it is important to have fun when attempting photography with your drone but you also have to remain sensible at all times. Do not go out on the streets on your first day having never flown a drone before because this can actually be quite dangerous. Also, think about where you are flying your drone; avoid flying near an airport where you could be causing serious problems. It all comes down to confidence and this will come with practice. The more you practice, the more you will learn and therefore the better your pictures will get!