(07-May-2017, 09:26 AM)Keyboard Kid Wrote: My main problem at the moment revolves around a lack of take-off power. My quad is an own design heavy lift quad (6kg) intended purely for take-off and landing the compound aircraft. No forward flight, no aerobatics. During the design stages I tested various motors and prop combinations and finally settled on Scorpion 3026/710 and APC 12 x 6SF props which delivered 2.1 kg or more of static thrust.
Thus in theory I should have at least 8kg total thrust.
However in preliminary testing I can only lift about 3kg.
So my question is where is the power going?
I realise that some power must be kept in reserve for inflight corrections but 5kg missing thrust is a bit much in my opinion.
Is there a setting somewhere that adjusts the amount of power available for take off?

(18-May-2017, 06:50 PM)unseen Wrote: It's the way these things work. Achieving movement on any of the three axes is achieved by using differential thrust on differing combinations of motors. If you use up all the available thrust just to get into the air, there's nothing left over to control the craft!

I've been looking at that time machine to go back a year and have a good chat with you, but I've not been particularly successful.



Unseen, that is the very first question I asked this thread. (See quote above) If power is held in reserve for in flight corrections there must be a setting which determines how much power is held in reserve. That is the setting I wish to locate and adjust in order to achieve an efficient balance between power delivered and stable flight.  Is there such a setting, what is it called and where do I find it?

This issue I believe is at the heart of my problem.

There is no setting for this. The craft has the power that the parts deliver. If you use parts that deliver a power to weight ratio of under 2:1, the craft might not even take off.
Conversely, if you build a craft that has a 6:1 power to weight ratio, it'll take off at about 25 - 30% throttle and have bags of power left before you reach maximum throttle.

(17-May-2017, 02:35 PM)sloscotty Wrote: I'm just curious if the Hero FC is somehow limiting full spoolup.  Have you tried disabling all the auto functions (GPS, altitude/range limatations, etc.)?  Were your thrust tests performed while connected to the Hero?

Slo, I think I have all those features turned off.

My thrust tests were carried out on my test jig using a Hefei KingKong ESC (60A) not the Hero.

Tomorrow I am going to lash down Wooden It and run the motors to full throttle and measure RPM at full throttle with my opto tach. That should at least give me some idea of what is going on.

I really would like to get some idea via a data log of some sort.

I am also going to try another FC to see if there is any difference in performance but all of these things take time and at the moment I am really busy with other things.

But they will come I promise you.

(18-May-2017, 02:51 PM)fftunes Wrote: Betaflight filter recommendations are meant for nimble miniquads, not for heavy ships like yours. You didn't mention filters before, so if you had lowpass already at 50Hz before it would mean that this is not likely to be an issue. It's ok to go that low on a bird that's not meant to flip and race nonstop.

Regarding PID, i'd say leave P where it is now, but increase I  to get rid of drifting. That "formula" you've seen is probably quite old and I-term behaviour changed a lot in recent versions. No problem to go higher there, i've seen examples of I-term as high as 85 even on small quads.

Thanks FF. That is a very useful tip.

(18-May-2017, 06:46 PM)unseen Wrote: Just like a real rotorcraft, unless you are flying in an assisted mode with GPS and all the bells and whistles, the flight controller has absolutely no idea of your position in 3D space. As wind and turbulence acts on the craft, it will move with these disturbances.

In manual flight modes, it's completely up to the pilot to achieve stabilisation of position.

If you are using a self-levelling flight mode, the accelerometer data will be used to correct attitude if the craft is not level and you have the pitch and roll sticks at neutral. If you are flying in 'rate' or 'acro' mode, then all the flight controller does is use the gyro to ensure that the rate of rotation around each of the three axes remains as you are commanding.

Hovering a quadcopter at a precise altitude and position is actually much harder than flying around!

Trust me to undertake the most difficult task first.
.
My primary goal has been from the outset to hover out the battery over the landing pad at a set altitude (approx 2m - 3m)

I am now up to 4min 20 secs which I am very happy with.

I adopted the same approach when learning to fly helicopters and found that worked well for me.

Thread moved and retitled. (And yes, everyone will come along.)

(19-May-2017, 12:50 PM)sloscotty Wrote: Thread moved and retitled.  (And yes, everyone will come along.)

Thanks Slo much apprectiated.

The big question is however, does evrybody want to come along?

(19-May-2017, 12:58 PM)Keyboard Kid Wrote: Thanks Slo much apprectiated.

The big question is however, does evrybody want to come along?

I think it might get even more attention here I'm also curious to see a pic or two maybe...? Would be cool to see how the "Wooden It" progresses over time.

Much easier not to overlook new posts!

I'm equally curious as to what the "Wooden It" actually is and what you're designing, although I can understand if you want to keep some of the details back if you're making something groundbreaking, especially on a public forum that's very well indexed by the major search engines.

(19-May-2017, 04:42 PM)unseen Wrote: Much easier not to overlook new posts!

I'm equally curious as to what the "Wooden It" actually is and what you're designing, although I can understand if you want to keep some of the details back if you're making something groundbreaking, especially on a public forum that's very well indexed by the major search engines.

You asked, I delivered. But not without some embarrassment!

Let me introduce you to Wooden It, as it first took to the air.

I did say it is unlike any quad you have ever seen.

Let me stress once again it has several prime functions:

(a)  To test motors, FCs and props with the view of finding the most efficient components in order to keep battery weight to an absolute minimum.

(b)  To teach me about the workings of quad components. A job it is performing well.

(c)  To teach me to fly a quad.

As I stated earlier I paid no attention to saving weight as it will be loaded up to 5.6kg eventually. Just ease of construction.

And yes I am working on an extremely radical compound transitional aircraft which I would rather at the moment keep under wraps if possible.

So there you have it.

KK

(20-May-2017, 01:17 AM)Keyboard Kid Wrote: You asked, I delivered. But not without some embarrassment!

Let me introduce you to Wooden It, as it first took to the air.

I did say it is unlike any quad you have ever seen.

Let me stress once again it has several prime functions:

(a)  To test motors, FCs and props with the view of finding the most efficient components in order to keep battery weight to an absolute minimum.

(b)  To teach me about the workings of quad components. A job it is performing well.

(c)  To teach me to fly a quad.

As I stated earlier I paid no attention to saving weight as it will be loaded up to 5.6kg eventually. Just ease of construction.

And yes I am working on an extremely radical compound transitional aircraft which I would rather at the moment keep under wraps if possible.

So there you have it.

KK

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!!

(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!!

Thank you Slo. That is a compliment indeed.

However perhaps I should clarify.

The mainframe is made from wood. What us old Aussies used to call "2 be 1" before metrification. Now I have no idea what it is called.

However, the pylons are fibreglass and are components from the actual finished aircraft, grafted on to Wooden It to test.

So my first lesson learned? Those pylons should have been an inch longer to accomodate a wider range of props.

You can also see some of  the headaches I face in such features as the lengths of wiring on the ESC.

The motors are placed as per the aircraft  and had the pylons been longer the motor placement would have been more square as against the rectangular placement at the moment.

Had Unseen let me finish that time machine none of this would have happened.

Live and learn as they say. And I have learned PLENTY!!

KK

(19-May-2017, 03:04 PM)fftunes Wrote: I think it might get even more attention here I'm also curious to see a pic or two maybe...? Would be cool to see how the "Wooden It" progresses over time.

FF The next two post show the progression of Wooden It over time as requested.

This one very early in its life. So early it is barely started but it does show where the name came from.

A great chunk of "2 be 1" with pylons attached.

Stage 3.

A very sad Wooden It with battle scars to show the cost of teaching me to fly.

Very early on my caper with the light fitting in the garage cost me one black pylon and 3 of the black original props.

Various bounces, thuds and whacks cost me another yellow pylon.

By this time the poor little end blocks supporting the pylons started to fracture and the only wood on the farm was a piece of floor board so the end blocks were reinforced with two chunks of floor board.

By this time I was flying with two 13 x 6.5 APC props, one 12 x 6 SF APC and one Aeronaut 12 x 5 Prop. The new props I have ordered are still not here yet. Nor are the new black pylons.

The original aluminium landing struts gave way by about the third flight and were reinforced with aluminium cross members and then finally aluminium lengthwise struts.

Those aluminium long struts can be replaced with steel struts to form part of the load. Each steel strut weighs 540g and I have 4 steel struts all told. At the moment I can only lift one steel strut and two aluminium struts.

And so the story staggers one.

But I have persevered and finally won out with 4 minute flights now routine and soft landings a breeze.

If I had tried to learn on the completed aircraft I would have turned it into slag within minutes so Wooden It has provided a vital service.

One final point, I have added a safety bar to protect me from accidents while plugging the batteries in under the mainframe and the floor board carry tray under the TX as well as the safety bar are removed before flying. Believe me I am terrified of and accident involving those props and motors.

The floorboard thing is all traditional farmyard stuff.

Now for the big battle and that is a flight fully loaded to 5.6kg.

Wish me luck

KK.

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