The standard for testing props seems to be the static pull test with the plane tied down to a force gauge and run at full power. This does not take into account all of the changing dynamics that occur as soon as the aircraft starts moving forward. The other tests are somewhat more arbitrary by doing takeoff performance tests or time to climb tests that are subject to human error and changes in atmospheric conditions.

I propose a different test using some sort of performance meter designed for the automotive world. There are several performance testers that operate using GPS and suction cup to the windshield that can be found for less than $1000. It seems like a test could be done where props were literally drag raced to 60mph on the ground. This seems a far better measure of prop performance than a static pull, and removes the pilot factor that is introduced when you try short takeoffs or climb tests.

I feel that by combining the drag race data and cruise speed data you could get a good overall picture of what a prop is capable of.

Thoughts?

I think that is a great idea.

I bought a big pull scale for the express purpose of doing pull tests. Some of the results of a static pull surprised me, specifically the pull comparison between the 82" and 88" prop on the 180. The 88" only pulled about 40 Lbs harder than the 82" under the same atmospheric conditions, and airplane weight. However, the first time I flew it with the 88" I noticed a much more significant improvement in takeoff performance (0-30 MPH ish) and even more so in the initial climb (30-60 MPH ish) than what the measly 40 pound static increase suggested.

Could you simply measure with an accelerometer? That's assuming a prop's best characteristic is acceleration.

We all have them in our phones.

https://itunes.apple.com/us/app/acceler ... 29589?mt=8

https://play.google.com/store/apps/deta ... eter&hl=en

I haven't tried either but they seem like they would report accurate data.

I thought of that as well. But if you are going to make a financial decision totaling thousands if not tens of thousands of dollars on a prop is seems like dealers and manufacturers could afford to spend the money on a calibrated device that uses GPS and Accelerometer data.

I also think the nicer ones record the time to 60 as well as all the intermediate times on the way there. That way you could see how many seconds it would take the light super cub to get to 30 as an approximate lift off speed or 50+ for a loaded Skywagon. If you run the test to 60 or even more for our non STOL counterparts you end up with all the data points along the way for any given prop.

I also think that the test should be made close to or at gross weight. The differences in acceleration might not be that apparent on an extremely light airplane, but on a heavy one the differences should show themselves more clearly

According to MT Propeller a static test is useless. The best way to see if you are using all HP available is to install a fuel flow meter. An IO 360 A1A should be using 18 gallons per hour on the take off roll at 2700 RPM. I am in the process of doing a first flight after installing a set of amphibian floats. I do not want to taxi test at 2700 RPM and have to abort a unwanted take off. I plan on having my friend use his truck hooked onto the float struts and allow me to taxi at 2700 RPM. MT tells me that the propeller needs to be in motion. I plan on taxiing at about 30 MPH and see what my fuel burn is. We will increase the taxi speed and see at what speed the fuel burn is at specified 18 GPM. If anyone out there has some comment or advise I would be pleased to read it.

hanger36 wrote:According to MT Propeller a static test is useless. The best way to see if you are using all HP available is to install a fuel flow meter. An IO 360 A1A should be using 18 gallons per hour on the take off roll at 2700 RPM. I am in the process of doing a first flight after installing a set of amphibian floats. I do not want to taxi test at 2700 RPM and have to abort a unwanted take off. I plan on having my friend use his truck hooked onto the float struts and allow me to taxi at 2700 RPM. MT tells me that the propeller needs to be in motion. I plan on taxiing at about 30 MPH and see what my fuel burn is. We will increase the taxi speed and see at what speed the fuel burn is at specified 18 GPM. If anyone out there has some comment or advise I would be pleased to read it.

Ensuring you are making full power is the right direction but also making sure the prop is efficiently using that power is the next. The propeller blade design may be wasting more of that power in drag vs thrust than another prop design

0 to a desired speed (like Vx or Vy) in seconds seems like a very good measurement but weight and density altitude will need to be taken into account and I bet the graph wont be linear.
An iphone app would be more than adequate.

My aircraft is experimental and is equipped with a supercharger. My airport is at 2400 feet. I will be running 30 inches at 2700 this should give me 210 HP. I gain about 6.5 HP. I am hoping to burn 18 gph. with IO 360 A1A. I am uncertain if this takes air density out of the picture I think that if air is lighter the supercharger just has to deliver more air to maintain pressure at 30 inches. Anyone know about this please reply.