(20-May-2017, 03:29 PM)sloscotty Wrote: I just noticed something in a couple of your photos that are a possibility for lack of performance.  If you are flying with any propellers mounted upside down, thrust on that motor will suffer.  The FC will compensate to keep the craft stable, but overall performance can be drastically reduced. (If you didn't fly it that way, then nevermind.)

Really like the rig, btw!

EDIT:  And please forgive me if I'm mistaken - it just looked like the propeller in the foreground of one of the photos was inverted (could just be an optical illusion).  Sorry

Slo, if the photo you are referring to is the first one in the series with bare wood you are right. In that photo I put 4 CCW SF props on just to get an idea of the effect.

I have always flown with the correct rotation props in place.

(20-May-2017, 03:29 PM)sloscotty Wrote: I just noticed something in a couple of your photos that are a possibility for lack of performance.  If you are flying with any propellers mounted upside down, thrust on that motor will suffer.  The FC will compensate to keep the craft stable, but overall performance can be drastically reduced. (If you didn't fly it that way, then nevermind.)

Really like the rig, btw!

EDIT:  And please forgive me if I'm mistaken - it just looked like the propeller in the foreground of one of the photos was inverted (could just be an optical illusion).  Sorry

Slo, I just looked at that photo again and you are right. That foreground prop IS upside down. I have no idea what I was thinking there.  Probably trying to make the two props in the CW position look different. At that time I only had 12 x 6 SF in sufficient quantities to fit four similar props. It was just a very early attempt to get some idea of the finished quad.

(20-May-2017, 01:41 AM)sloscotty Wrote: Well, it was certainly not what I expected from your description!  I can't tell any of it is made from wood.  That looks AWESOME!!

Slo, I must say I am pleasantly surprised by your reaction to Wooden It.

I was really embarrassed when the subject of photos started to be raised. At the very least I expected to be the recipient of a round of serious ribbing.

It really is radically different to any quad I have ever seen as will be the finished project. I suppose I just did not know what to expect.

Anyway thanks for the great support.

As hard as it has been, looking back it has been intensely satisfying to meet and overcome the obstacles encountered so far. Let us hope that I meet and overcome the looming obstacles.

KK

I like the fact that you didn't just reach for a big 680mm frame kit and build. As things get bigger the material choices open up and the weight becomes less of and issue compared to cost.

Howdy All,

I had a chance to do the first run on the motors with the quad anchored firmly to the ground and using my opto tachometer.

The result was sad to say, less than satisfactory.

Of the four motors on full throttle, the two CCW motors gave poor readings of 1,500 and 3,300. The two CW motors both gave identicalreadings of 6,100rpm each. This is well down on the 8,000 RPM recorded on the graph attached, plotted using my test rig and Hefei KK ESC. The props used were the Aero 12 x 5 and the battery a LiHV as per the graph.

I feel that I really cannot take much notice of this test as the two hardly spinning motors confuse me.

I felt that the quad was as level as possible but obviously not level enough.

I will try again tomorrow. This time I will use the Betaflight as a levelling device.

KK.

And now something to break the monotony and a little closer to the spirit of this forum.

In 2004 I was invited to fly in a show held on Farnborough Airport, UK. I could only take a small model so I had to make do with some primitive equipment I am afraid.

Remember this was 2004 and the camera was just a mini surveillance camera. I had no room for my OSD and the day was a shocker. Heavy overcast and 24knt winds. Still we flew and all went well and the show was well received. 

The attached photo is a screen grab from one of those videos I recorded while flying just off to one side of the main runway. I was under Air Traffic Control at all times but as the ATC people became more confident in my flying and cooperative attitude, they became more relaxed and allowed me to move around in a slightly wider area. Thus I was allowed to fly up the main runway as pictured. A very treasured memory of a great day.

The camera was mounted on the outside of the model and the video was transmitted to a receiver in the Airport reception hall and displayed on a large screen TV for the audience to enjoy.

We were then taken on a tour of the old wind tunnels and whatever was left after the Airport was being sold off to developers. That was the sad bit.

Anyway from the UK we went to Florida in the USA and that is a whole other story.

Great memories.

KK

To finish, the photo attached is of the small aircraft I took to Farnborough.

It is a semi scale Aerocommander. Very fast, highly maneuverable and fitted fit flaps, it was a great plane to fly.

(21-May-2017, 07:20 AM)Keyboard Kid Wrote: Howdy All,

I had a chance to do the first run on the motors with the quad anchored firmly to the ground and using my opto tachometer.

The result was sad to say, less than satisfactory.

Of the four motors on full throttle, the two CCW motors gave poor readings of 1,500 and 3,300. The two CW motors both gave identicalreadings of 6,100rpm each. This is well down on the 8,000 RPM recorded on the graph attached, plotted using my test rig and Hefei KK ESC. The props used were the Aero 12 x 5 and the battery a LiHV as per the graph.

I feel that I really cannot take much notice of this test as the two hardly spinning motors confuse me.

I felt that the quad was as level as possible but obviously not level enough.

I will try again tomorrow. This time I will use the Betaflight as a levelling device.

KK.

Sounds like it's trying to yaw.  Since it's tethered, it can't.  If you have magnetometer or GPS enabled, I would disable them for testing.  I think I would also turn of accelerometer while testing.  If the FC detects even a slightly "out-of-expected" orientation, it will try to correct by spinning some motors faster, others more slowly.  If it can't correct, it will try even harder.  My thoughts anyway.

(21-May-2017, 11:15 AM)sloscotty Wrote: Sounds like it's trying to yaw.  Since it's tethered, it can't.  If you have magnetometer or GPS enabled, I would disable them for testing.  I think I would also turn of accelerometer while testing.  If the FC detects even a slightly "out-of-expected" orientation, it will try to correct by spinning some motors faster, others more slowly.  If it can't correct, it will try even harder.  My thoughts anyway.

Slo I think you are right. I had not thought about correcting a yaw. I was thinking about it trying to level itself when it was already close enough to level. Correcting the yaw fits perfectly.

I will try one more time this time with the Betaflight attached and see if I can find some answers that way.

Great tip Slo.

(21-May-2017, 06:50 AM)l Aaron Wrote: I like the fact that you didn't just reach for a big 680mm frame kit and build.  As things get bigger the material choices open up and the weight becomes less of and issue compared to cost.

Hi Aaron, welcome on board.

To explain why picking up a 680mm kit was not possible you need to understand the following.

Wooden It fills a particular purpose which calls for the motors to be in the exact location you see them on Wooden It. A kit would not meet this requirement.

Put briefly Wooden It is simply a test bed for the motors/props/ and batteries that will be used in a much more complicated project which has yet to be built.

A second and equally important function is to teach me to fly quads. A task it is fulfilled admirably.

All of this is explained in the previous pages of this thread.

Regards,

KK

(21-May-2017, 01:07 PM)Keyboard Kid Wrote: Slo I think you are right. I had not thought about correcting a yaw. I was thinking about it trying to level itself when it was already close enough to level. Correcting the yaw fits perfectly.

I will try one more time this time with the Betaflight attached and see if I can find some answers that way.

Great tip Slo.

If all you want to do is test the speed the motors will spin at, then you should use the motor test tab in the Betaflight configurator to control the motor speed.

Actually arming the craft and using the live flight controller to control things will do all kinds of strange things if the craft is tethered.

(21-May-2017, 11:15 AM)sloscotty Wrote: Sounds like it's trying to yaw.  Since it's tethered, it can't.  If you have magnetometer or GPS enabled, I would disable them for testing.  I think I would also turn of accelerometer while testing.  If the FC detects even a slightly "out-of-expected" orientation, it will try to correct by spinning some motors faster, others more slowly.  If it can't correct, it will try even harder.  My thoughts anyway.

Slo I think you have hit on a solid part of the answer to where the power is going, if not the whole answer.

If that quad is pinned to the ground by extreme weight and the heading is not zero then it is going to present exactly as I saw it today with two motors virtually idling and thus no power for take-off.

I have noticed down on the farm in the past that one or more motors will occasionally run slower than the others before take-off.

So the question is how do I ensure that the heading is zero prior to take-off to ensure that all motors are fed equal power?

Today I did not move the quad after it was switched on and callibrated so I would have thought that the heading would default to zero.

However down on the farm I plug everything in on the courtyard table and carry the quad unarmed across to the helipad, a distance of about 100 yards. Hence the prop lock. Under these conditions I can foresee the heading not being zero when I place the quad on the ground. I also face the front of the quad into the wind which can of course be coming in from any angle.

I use the table to save my bad knees when plugging the batteries in.

So as I said, what do I do to ensure a zero heading when placed on the ground? Any ideas Lads?

KK.

The flight controller does not have a magnetometer, therefore it has no idea which way it is pointing. The heading is therefore set to zero when you arm.

The important thing here is to understand that it wasn't trying to yaw to correct any heading difference as when you are flying manually there is neither a commanded heading, detected heading or any error between them to correct for.

So why would it be attempting to yaw?

The only explanation can be that it was being commanded to yaw. When your sticks are centred, what channel values are shown in the configurator? They should be at 1500. If your yaw (rudder) channel isn't at 1500, then you will be commanding the craft to yaw.

So, check your centre values. If they are at 1500 but jitter around a bit between (say) 1498 to 1502, you should set some deadband to ensure that the jitter isn't interpreted as a command. If they are not 1500, you should use your radio's subtrim to make the centre value 1500 as it should be.

(21-May-2017, 02:27 PM)unseen Wrote: If all you want to do is test the speed the motors will spin at, then you should use the motor test tab in the Betaflight configurator to control the motor speed.

Actually arming the craft and using the live flight controller to control things will do all kinds of strange things if the craft is tethered.

Yes. When pinned to the ground, the slightest bit of noise (or rc command jitter) can/will add up to some error eventually, to which it will react by lowering certain motors when you are commanding full throttle. And since it can't correct that error, those "correction calls" will become stronger and stronger. If the quad was in the air, you could expect all motors to run at pretty much equal rpm readings.

As unseen said, to test motors, one way would be running the motors from motors tab in the configurator without arming from tx - this would prevent the PID from becoming active and commanding motors down (or up if not at full throttle).

Another way would be, to use tx to command throttle but set all PID to ZERO so they have no effect at all, in order to allow all motors to go full throttle. You can use a second profile in betaflight to not erase your previous settings (in PID tab of the configurator).

I believe he was using the TTRobotix Hero FC in his first tethered test (correct me if I'm wrong KK). The Hero does have a GPS Compass module, and (if I read the docs correctly) it is required to be plugged in for the FC to operate. I don't know if he has a motors tab to use with that FC. (I think he also mentioned swapping out to a Betaflight FC to repeat the test.)

(Unfortunately, I can't help him much with Hero questions like "how to zero heading".)