A riddle wrapped in a mystery inside an enigma?

Originally Posted by _OZ_

A riddle wrapped in a mystery inside an enigma?

.... that creates a whole new paradigm.

Too much fresh air today, I guess. Sorry.

Originally Posted by Aeroplayin

The challenge for all of us, and the initial focus of any ongoing analysis in this thread, I feel, will be to put this all to the test again in order to explain the contrary observations we have heard from people who have compared the APC and Xoar in the air -- APC with more Watts and Amps.

We should try to establish this conclusively. My 15x8 and 16x8 tests will be coming soon, along with some video evidence, since the props have now arrived from Lee and the rest were bought from Graves RC. I now also have a 14x7 Xoar to compare on the Motrolfly 2820-680 against the 14x7 APC on the 48 inch Edge. I can also get a 12x6 Xoar to compare on the Torque 820Kv motor with the 12x6 APC.

Yes a second test!

Like Frank I am super glued to the APC Xoar show down on the bench and in the sky. I don't care how it all turns out I just want to know the truth and the facts not hearsay and urban legend.

P.S. Aeroplayin I just rough tested both a APC and XOAR 14x7 and the results were very very similar to the APC and XOAR 15X8 data. You kind of knew I would. I await your 14x7 /15x8 retest and the results of the 16x8.

In other news my frankinstein carbon fiber prop isn't panning out. I tried cutting down a Mejzlik 16x8 to a 15x8 and then to a 14x8 too see if I could yeild a magic power system specific repeatable prop. The Mejzlik was just too heavy and the airfoil profile was too thick to begin with. Ya just don't know until you try. We will just have to wait until Xoar makes a 16x8 or 15x8 carbon fiber.

Who knew this would be so interesting and would capture the imagination and attention of so many pilots. It's cool, it's hip, it's happin and it's driving out wonderful knowledge share.

And what the???

Originally Posted by _OZ_

A riddle wrapped in a mystery inside an enigma?

Originally Posted by Aeroplayin

.... that creates a whole new paradigm.

Too much fresh air today, I guess. Sorry.

Too much fresh air my Call this a freindly intervention but its time for someone to layoff smellin the super glue. lol

Originally Posted by Tom K.

Oh... whoops Then what was pulling 10lbs? lol

--Tom K.

10-11 lbs is more like the thrust level of the Motrolfly 4315-480 on 6s with 15x8 prop.

Vien

What about a simple POLL asking what prop/watts in , is your prefference for the various EF models. I would gear up my 48" powerplant for the majority polled winner.

FWIW I would have never known/guessed an APC 10X4.7 SF would be such a winner @ 300-400Watts for 24-26 oz airframes. I like it much better than Xoars I tried for this weight range, this is the kind of data I think a poll would bring to light.

Originally Posted by Aeroplayin

Just remember that Watts at the meter may not be telling the whole story and can be representing a segment of the load that is not going to power the prop. If you are over-propped, this meter reading can be an enigma.

Aero, what watts in tells me is exactly what weight range battery you have in your airplane, This is a key componenent number as to cg/Flight characteristics in thrust to weight and wing loading given the final weight of a given EF model will all be nearly the same. It really has no significance to me as to static testing or what kv/cell count I may gear up for.

For instance if I want to put 100watts into a given prop, my formula would again say 10g battery nets 25 watts ouptut, so to get to a 100 watts into a specific prop it would be roughly a 40gram battery it doesnt matter if I use a 1s @ 26 amps or a 10s @ 2.5 amps if both batteries are 40 grams it is going to spin that prop roughly the same rpm calculated with appropriate KV motor.

What one may find worth exploring, that I feel is being done in helis and not planks is that wattage coming from voltage versus amperage will be the next best thing. It may just be the ease to which voltage flows in hardware versus amperage.

I am always amazed when people think that increased cell count is a speed thing.......

c/f, I don't understand the battery weight to watts relationship. Also, how do you know how many watts you want through a prop? Finally, can you post your formula?

Originally Posted by leespaddock

Good insight. I think this forum is headed in that very direction. I also appears that many people have been hoping and wishing for a thread just like this one. Eventually seperate sections / posts for each EF Plane. Measurable Data, Subjective Feel and Owners recommendation for each plane. Agreed there is a magic prop, esc, lipo and motor combination for a particular flying style and plane. I see EF continuing to do the major upfront research and it will be up to the flow down owners to experiment and refine from EF's initial recommendation. EF doesn't have the time to test every imaginable combo, however all of the EF plane owners do and that is how we together will crack the magic power system code for each plane. Just my thoughts.

Really Herc snaps props mid-air, sounds more like an urban legend to me. No offense to Herc and his mega agressive flying style. The prop in question has to have taken a few ground hits or been flown alot and I mean alot of 3D too create the kind of stress fractures and imbalance needed to break a prop mid-air. However if a paticular prop is blowing apart in the air after a certain flying duration that is great info to share with everyone. It is not unreasonable to think there is a flying time limit for any prop not unlike any other part of an aircraft large or small, manned or unmanned.

Lol you guys are too much. In terms of EF planes I have broken a couple props in the air. Both of them were 12/6 APCs on the stock setup. In each case the prop had 100s to 1000s of flights and you could see stress marks on the blade where it had been flexing through gazillions of revolutions. I could see the prop actually start to break at the trailing edge several flights before they actually sheared off.

** This was a known issue with those props and APC now sells that prop with a thicker hub and center blade.

I run the APCs on the 48" because it is so low the the ground that I find it more durable.

On everything else I run Xoars. The lighter prop is easier on ESCs, bearings, X mounts (break those all the time) and the plane.

Originally Posted by hercdriver7777

Lol you guys are too much. In terms of EF planes I have broken a couple props in the air. Both of them were 12/6 APCs on the stock setup. In each case the prop had 100s to 1000s of flights and you could see stress marks on the blade where it had been flexing through gazillions of revolutions. I could see the prop actually start to break at the trailing edge several flights before they actually sheared off.

** This was a known issue with those props and APC now sells that prop with a thicker hub and center blade.

I run the APCs on the 48" because it is so low the the ground that I find it more durable.

On everything else I run Xoars. The lighter prop is easier on ESCs, bearings, X mounts (break those all the time) and the plane.

Thank you Herc for the great info. Im Givin ya some deserved "props" as your flyin skills are darn near legendary.

My approach on this thread is going to be focused on completing the data collection and analysis using an specific process. The reason I’m going to approach it this way is because many guys want to take a lot of momentum/speed into a big tumbling/spinning maneuver, and for this, they may need a setup different than the guy who wants to segway from one full stall maneuver to another in a relatively small box, or airspace.

These two differences generally relate to prop speed (pitch and rotation) versus torque (diameter and rotation – an over simplification, I know). My focus will be about power… instead of how much it takes to move a 250 pound fireman up a 40 foot ladder in 1 minute, I’m interested in the prop type (make and model) that when applied to a specific motor and battery combination will hold a 5.5 pound airplane suspended in a hover with less throttle setting, and pull the 5.5 pound plane over a greater vertical distance in less time when the throttle is moved instantly to WOT.

There are also two Watts variables in this analysis that need to be defined. The meter reads volts and Amps and multiplies the two and displays this value in the Watts output field of your meter. The meter is doing the math, and not really measuring the power (749 Watts = 1 HP) a system needs to turn a propeller with a specific diameter, pitch, and mass, a specific number of RPMs.

The assumption will be that turning the same prop faster will generate more measurable thrust and require more power (Watts), in some relative way unless prop stall or pitch distortion is the result.

This is how I will proceed, and I’m open to suggestions, but anyone can add their input and findings by doing the following so that we can maintain a standard. Here's a standard checklist that I came up with.

Location or Elevation
General Wind Conditions and Air Temp
Weigh your all-up airplane, RTF
Motor Make
Motor Kv
ESC Make
ESC Amp Rating
Battery Make
Number of Battery Cells
Battery mAh
Battery C rating
Prop Make
Prop Model
Prop Length and Pitch
At-Rest Volts on the startup stand
Half-Throttle Volts on the startup stand
WOT Volts on the startup stand
Half-throttle Amps on the startup stand
WOT Amps on the startup stand
Half-throttle RPMs on the startup stand
WOT RPMs on the startup stand

At this point, go fly around at half throttle for a full minute. With the video camera on, pull into a hover and hold it level for at least a few seconds.
Punch the throttle to WOT and hold it until the plane climbs to at least 75 to 100 ft. Fly around for another minute at about half throttle and then land the plane.
Keep track of your total flight time, and take a volt reading of you battery after 5 minute at rest.
Put the battery back on the charger and record the mAh that was put back. Add the following to your checklist.

Flight Time
Post Flight Volts
Returned Capacity (mAh)

Put the video on Youtube and link us up in a posting on this thread along with the above data. If you can do this with different motors, batteries, and different props, great. But any meaningful data that you can contribution will be appreciated, and I think it is the core of what will make this thread valuable. If we can get just four or five guys to follow all of these steps using different setups, we can probably start accumulating something very valuable to everyone. Tom, Frank, and I will have some fun with this over the next few weeks.

Originally Posted by Aeroplayin

My approach on this thread is going to be focused on completing the data collection and analysis using an specific process. The reason I’m going to approach it this way is because many guys want to take a lot of momentum/speed into a big tumbling/spinning maneuver, and for this, they may need a setup different than the guy who wants to segway from one full stall maneuver to another in a relatively small box, or airspace.

These two differences generally relate to prop speed (pitch and rotation) versus torque (diameter and rotation – an over simplification, I know). My focus will be about power… instead of how much it takes to move a 250 pound fireman up a 40 foot ladder in 1 minute, I’m interested in the prop type (make and model) that when applied to a specific motor and battery combination will hold a 5.5 pound airplane suspended in a hover with less throttle setting, and pull the 5.5 pound plane over a greater vertical distance in less time when the throttle is moved instantly to WOT.

There are also two Watts variables in this analysis that need to be defined. The meter reads volts and Amps and multiplies the two and displays this value in the Watts output field of your meter. The meter is doing the math, and not really measuring the power (749 Watts = 1 HP) a system needs to turn a propeller with a specific diameter, pitch, and mass, a specific number of RPMs.

The assumption will be that turning the same prop faster will generate more measurable thrust and require more power (Watts), in some relative way unless prop stall or pitch distortion is the result.

This is how I will proceed, and I’m open to suggestions, but anyone can add their input and findings by doing the following so that we can maintain a standard. Here's a standard checklist that I came up with.

If we can get just four or five guys to follow all of these steps using different setups, we can probably start accumulating something very valuable to everyone. Tom, Frank, and I will have some fun with this over the next few weeks.

Looks like a very thorough flight test methodology. If flowed by each tester it should provide consistent repeatable results.

I see where your going with the flight test as any kind of completely subjective based test would just be disputed and thus really not provide good research value. A dammed if you do dammed if you don’t senerio.

My only suggestion for your consideration would be a timed and measured WOT level pass in addition the hover to WOT vertical climb. I think it would give pilots an idea of the airplane speed difference created by different pitch props, put a little more load on the system and add to the end results data. To pull off a simple level flight speed test you could grab a radar or Lidar gun and just document the flight speed. If you don't have one you could do a few high speed donuts with your car in front of a state patrol and make them chase you at high speed to the field for flight testing. What's a little jail time, this is life or death important testing and I am sure the stater will completely understand. I will post your bail, Not! lol

Thank you in advance for all your work, effort, support and thoroughness regarding this very very interesting topic and the important development of standardized prop testing methodologies. I think once both are refined the std bench and flight testing guidelines should be posted at the front of the thread.

I owe you some more data my friend. Once complete I will send you my WOT and 50% throttle bench test results for the APC and Xoar 14x7 comparison.

Kindest Regards,
Lee

Originally Posted by leespaddock

My only suggestion for your consideration would be a timed and measured WOT level pass in addition the hover to WOT vertical climb.

We'll take anything we can get, and the only problem is that wind conditions, upwind and downwind passes, etc, will make the visual element a little tough as far as objectivity. If you look at Tom's video from yesterday, you can see the plane moving at wharp speed downwind. Not as helpful in comparison to no wind conditions, which may not happen for us until June. Weather Underground said steady 14-15 mph winds and gusts to 26 yesterday at Sarasota Airport. But like I said, if you have it, add it.

Originally Posted by Aeroplayin

We'll take anything we can get, and the only problem is that wind conditions, upwind and downwind passes, etc, will make the visual element a little tough as far as objectivity. If you look at Tom's video from yesterday, you can see the plane moving at wharp speed downwind. Not as helpful in comparison to no wind conditions, which may not happen for us until June. Weather Underground said steady 14-15 mph winds and gusts to 26 yesterday at Sarasota Airport. But like I said, if you have it, add it.

Ah yes wind! My bad. There I go with my perfect windless test environment that only exists in my head.

On another silly note. Here is a vid of something I want to build for my dog for Christmas.

When an engineer owns a dog-Funny!!! (1 min 25 sec)

Perpetual doggy fun 24/7.

All the factual data is good but one thing I believe we all want to know is...

1. What did each pilot like about each prop and why?
2. And dislike about each prop and why?
3. What prop do they choose to fly?

Regards,

JC

ps - Getting 4 or 5 guys with videos is a most excellent idea!

Originally Posted by JC Spohr

1. What did each pilot like about each prop and why?
2. And dislike about each prop and why?
3. What prop do they choose to fly?

The subjective note about the results is an excellent idea. I've heard the Xoar experience explained more subjectively than any other prop I can think of, so it will be interesting to hear what people say after they witness the objective results too. I've heard things like softer, forgiving, smoother, docile...

I may actually return to the Xoar myself, until the 14x7 I'll be putting on the 48 inch Edge, and the 16x8 on the 60 inch, clips the ground a few times and begins to cost me in time and money to replace them. But they may be worth it. Let's see.