Run 5 motors off 4000 mAh battery and Matek F765 flight controller?

[OwenN]

Aurora rc d1306 3100 KV 4S motor specs volts, amps, prop size, thrust.

I cannot find manufacture specs for this. It says 7.9 amps max, 12g weight, 3-4 inch prop.

The amps sound rather low. free speed is 51,770. (calc)

I would expect 25,000 static with a 3 inch prop.

If it has a 5 inch pitch, that is 52 m/s.

A = 4.5 x 10^-3 m2

T = 2x dens x V^2 x A = 30 N or 3 kgf

Watts = TV = 1560

and amps = 1560/16.7 = 93 A without considering losses!

I wouldn''t really expect more than 30-odd amps from such a small motor, so revs must be much lower.

Even the 2805.6 motor with the 9 inch prop only used 54 A, 866W , and made 2 kg thrust!

What do you think? do I need to go up to a bigger frame size to get to 15 amps?
I want about 300g thrust.

How about a 2200 series? they are much heavier at 29.3 g
for a 2207.5 1922 KV Hyperlite HV edition.

What is a comparable motor with an available performance spec?

If I want 300g thrust, V = 17 m/s, rpm = 8031, watts = 51, amps = 3!

so is it truly draws 7.9A and is reasonably efficient, it should easily make 300g thrust.

Calculate expected thrust at 15 amps, 60% efficient?? 15 x .6 = 9, watts = 9 x 16.7 = 150

VT = 150, T= 2 den v^2 A, so

V = cu rt(150/2 den A) = 23 m/s

T = 2 den V^2 A = 5.7 N = 570 g thrust....

 

[PsyBorg]

I'm not finding anything but sales pages for that motor.. cant even find the company to dig thru the products pages.. I'm gonna step out on a limb and say this is one of them knock off motors of some other brand. So I searched similar motors and came up with this.

http://www.rotorbench.com/DYS_1306_3100kv/

 

[OwenN]

I'm not finding anything but sales pages for that motor.. cant even find the company to dig thru the products pages.. I'm gonna step out on a limb and say this is one of them knock off motors of some other brand. So I searched similar motors and came up with this.

http://www.rotorbench.com/DYS_1306_3100kv/

What is the interpretation of these graphs?
I assume HQ5030 CFN-cut is a propeller with the tips cut off, and 11.39 amps at 300 g thrust, but what voltage,
and which prop does best?

I want to run mine in a tube, so there is some tip flow efficiency, some drop-off due to the motor blocking flow, and the motor supports,
, the wall surface drag, and some Coanda gain if I have a nicely rounded inlet.

I will look for some props with square tips.
3 blades should be sufficient, as the motor will just slow down with more blades.
Can I go to 4 inch blades and cut the tips off if I want the square tips?

 

[OwenN]

I see all of these are GemFan 2 bladed props., and the GF4045 CFN is not available.

These also seem to be carbon fiber. Would a 3-blade polycarbonate blade make less thrust with this motor?
Do I need more blades if the prop is ducted? There are a few available specially for ducted quads.

Gemfan Cinewhoop 75MM Tri-Blade Propellers
Gemfan D76 5-Blade Ducted 76mm (3″) Propellers (Set of 4)
HQProp 75MM For Cinewhoop Grey
HQProp Cinewhoop Duct-3 Propellers (Set of 4)
HQProp Duct 75MMX6 CineWhoop Propellers (Set of 4)
iFlight Nazgul 3040 Tri-blade CineWhoop Propellers (Set of 4)

I would have thought you would need a bigger frame motor in the 2200 range to make use of these.
They would be so inefficient with the 1306 motor that they would produce less thrust.

Should I try a 2-bladed prop in a duct? Does it need to be a fancy carbon fiber one?

 

[b-29er]

I don't mean to sound condescending, but you might be better off getting an e-flite Convergence so you get VTOL Experience with a proven platform that you can buy replacement parts for? It kind of sounds like you're bouncing all your R&D questions off us for something you're not entirely familiar with, including how you might control a VTOL aircraft. And what i'd hate to see is you start off on this project, get a lot of money and time invested, then not be able to fly it because the thrust design was off or the controller won't do what you want it to or you don't know how to fly the thing and it turns into a shelved project you pawn off at a swap meet.

 

[OwenN]

I don't mean to sound condescending, but you might be better off getting an e-flite Convergence so you get VTOL Experience with a proven platform that you can buy replacement parts for? It kind of sounds like you're bouncing all your R&D questions off us for something you're not entirely familiar with, including how you might control a VTOL aircraft. And what i'd hate to see is you start off on this project, get a lot of money and time invested, then not be able to fly it because the thrust design was off or the controller won't do what you want it to or you don't know how to fly the thing and it turns into a shelved project you pawn off at a swap meet.

I am sure the Matek and Ardupilot will work as advertised. I just need to do the reading and watch the videos.

As long as the weight trim is reasonable, it will fly. I will check the COG offset so that 200-250 g thrust is enough to swing the angle of attack.
I will also check for pendulum effects.

Probably a 3-stick controller is needed to gradually rotate the props/motors, especially if the angle of attack is low.
At or above 45 degrees, you can slam it into flying orientation and it will just go; like a tail-sitter, or a jet on a short ramp.

I will look on-line for examples of working 3-stick transmitter-controllers.

I am sure we are ironing out any problems now, before the "thing" is built.

Making sure I get the best out of a 1306 motor is one thing to check.

This has all been done before, many times. I just need to find the videos.

I already have a few. Putting together a good pivot mechanism, with nice low-slop bearings and good pivot pins etc , is the next step.

I am competent enough in metalwork and balsa working, and mechanical drawing, so If I have something good to copy, it will turn out OK.

 

[b-29er]

I am sure the Matek and Ardupilot will work as advertised. I just need to do the reading and watch the videos.

As long as the weight trim is reasonable, it will fly. I will check the COG offset so that 200-250 g thrust is enough to swing the angle of attack.
I will also check for pendulum effects.

Probably a 3-stick controller is needed to gradually rotate the props/motors, especially if the angle of attack is low.
At or above 45 degrees, you can slam it into flying orientation and it will just go; like a tail-sitter, or a jet on a short ramp.

I will look on-line for examples of working 3-stick transmitter-controllers.

I am sure we are ironing out any problems now, before the "thing" is built.

Making sure I get the best out of a 1306 motor is one thing to check.

This has all been done before, many times. I just need to find the videos.

I already have a few. Putting together a good pivot mechanism, with nice low-slop bearings and good pivot pins etc , is the next step.

I am competent enough in metalwork and balsa working, and mechanical drawing, so If I have something good to copy, it will turn out OK.

Everything can fly. once. The trick is that second flight...I've never heard of a 3-stick setup on a VTOL. Usually it comes down to a switch with a time delay or a roller to implement vtol engine tilt. You can watch as many videos as you like, but that doesn't replace experience with the electronics, replace familiarity with software and configuring ArduPilot to work with your VTOL design, and replace stick time.

Best of luck.

 

[OwenN]

Everything can fly. once. The trick is that second flight...I've never heard of a 3-stick setup on a VTOL. Usually it comes down to a switch with a time delay or a roller to implement vtol engine tilt. You can watch as many videos as you like, but that doesn't replace experience with the electronics, replace familiarity with software and configuring ArduPilot to work with your VTOL design, and replace stick time.

Best of luck.

I have a couple of vtol and tilt-prop build videos. I will see how they do it.

I will also go through the Ardupilot and Matek setup videos carefully.

Having worked in business software, (now retired), I got quite good at deciphering instructions..

I think the trick to getting it working right is lots of short, low, lift-offs and landings, over grass.
Also careful preflight testing.

that way, I can have a few small crashes without severe damage.

The good thing about VTOL operation, is it happens fairly slowly!

-hit the throttle kill quickly before it gets away, and don't use huge excesses of thrust.

I am sure with at least 2.5 thrust-to-weight, it can get quite high very quickly.
(<edit> with 2.5 x thrust to weight, excess acceleration is 1.5 Gs)

<correction> units error -acceleration at 1.5 G really is a "warp speed" launch.
17 m/s(40 mph) (V) is reached in :
at = 17m/s
a = 9.81 x 1.5 = 14.7 m/s2

t = V/a = 17/14.7 = 1.15 seconds! (estimated stall speed).

distance s = 1/2 at^2 = 14.7/(1.15)^2 / 2 = 9.7 m (32 ft).

60 mph ( 26.4 m/s) takes 26.4/14.7 = 1.8 seconds, and travels 14.7(1.8)^2 /2 = 23.8 m (78 ft).

If it yanks off the ground that quick, the center of plan area is well behind the prop, so it will pitch up

without the front thruster.

Thus, the flight controller can be set to initially rotate the motors in sync with angle of attack, then finish off the last 45 degrees in 0.5 seconds-basically full actuator rotation speed.
-hence no outside control needed.

The thruster is more important in landing, because if it lands at a tilt, the thruster will help braking and help drop the nose down gently
when the main motors are shut down. otherwise, it will bang down rather quickly.

The low density of the forward fuselage and front wing resistance may slow the drop a bit.

The worst hazards will occur during high speed manoeuvres, which are likely to cause bits to fall off-elevon flutter,
fatigue fracture due to vibration, oddball resonances overstressing components,

not allowing enough pull-up height, collision with trees, occlusion by trees, hills, some control oscillation not allowed for by the gyro

stabilisation, accidently reversing elevator when too close to the ground, setting transmitter control sensitivity too high,

crashing into fences, unrecoverable spin/stalls, not doing pre-flight control direction checks, flying into another aircraft, etc.

Speaking of unrecoverable stalls, I saw a beauty on one of the crash videos. It was a flat, slightly nose-down spin,
and the tail was skidding sideways-fully stalled and masked, no doubt.
This autopilot could counter that by using differential engine thrust to oppose direction of spin, then muscle up to flight speed.

 

[OwenN]

here are some tilt system variations. Which would be easiest to make by hand?
The "Tilty Tilt" version looks overcomplicated. It doesn't show the rotary bit, though, or how it fits into the pod.

None really show how the second bearing works. one bearing is the actuator itself.]

The output from the actuator could be a cut-down cross-shaped arm.

The whole motor pod ends up being excessively wide. It would be nice if the linkage and mechanism would fit into a 40mm
wide housing.

this is the housing width that takes the 2806.2 motors on their channel bracket, then 2.4 ply each side.
The motor mount channel could be thicker, and pick up the pivot bearings, as in images 1 and 2.

I shall have to draw up some simple designs. I really need a smooth shaft and bearing. How about a screw center, brass tube over it ,
another slice of brass tube, epoxy bond into metal yoke?

Or number drill for brass inner, in an aluminium yoke?

I have some nesting tubes. I will see how well they fit together.
How big an actuator? 1.5 kg/cm metal gear, or bigger? There is no real torque involved.....

I shouldn't be able to force it to turn by hand easily. What are the internal actuator gears? Worm and Wheel?
The new Nimbus version shows how the cabling should fit.

I haven't found a video yet that discusses tilt control strategy.
I have a few to watch on Avatar Bi-copters yet.

 

[OwenN]

Here is an aspect I haven't thought through yet.
What happens if a landing approach is done with the rotors tilted up to 30-45 degrees?

The airflow over the wing will force the tail down, and it will drop into a tail-sitter style attitude sooner.

the motors can be automatically rotated to keep point up or forward.

When the tail hits the ground, the rotors can be angled back to assist "folding" the aircraft onto the ground.

Some groundspeed must be maintained to make the aircraft fall forwards on landing.

The props could also be tilted down. What affect does this have? The plane would travel forward with a lesser tail-down angle.
Under these conditions, the front thruster is not needed.

It only value is if you wish to hover, and most of the prop airflow misses the wing. then it will have a nose-down trim.

Would a transition to hover be possible when landing? You would have to prematurely go to full-up motor tilt,
in order to avoid forcing prop air over the wing, and fly a nose-up approach on elevators, to bleed off speed.

Then the nose thruster could be used below stall speed. This landing profile will need experimentation.
It may still naturally adopt a tail-down attitude. due to angle changes of the motors, putting more prop wash over the wings.
Alternatively, the effective backward rotor tilt will slow the aircraft down quicker.

These differing flight profiles would suggest that either:
1) there was a landing profile selection switch; or
2) there was full tilt control from the ground controller.

 

[OwenN]

Another interesting pivot bearing option:
Shoulder washer, nylon
Shoulder sleeve bearing, various plastics.
I will check my brass tube and see if I can find one that matches.

 

[OwenN]

Here are a bunch of smaller metal gear servos- one has dual ball bearings, -helicopter swash plate use? Is there a preference for one of these? The ball-race one might make a better motor pivot bearing.

 

[OwenN]

This is my favourite. By Digital I presume they mean PWM.! Not uart + power supply, or some other scheme. Dimensions scaled approximately.

1:1 scale drawing.

 

[Ketchup]

Actually digital does not mean PWM. So there are two types of servos, analog and digital, and while I don't know the exact difference between analog and digital servos, I know that both should use PWM. From what I just read the servo receives a signal from the receiver and converts it into signal pulses for the servo motor. The difference between digital and analog is that digital servos send pulses more frequently, so they have a higher resolution and are more precise, but correct me if I'm wrong here. In my opinion you wouldn't really notice the difference if the servos are in a plane that you are flying unless you fly big 3d planes and stuff that need that level of precision.

 

[PsyBorg]

What is the interpretation of these graphs?
I assume HQ5030 CFN-cut is a propeller with the tips cut off, and 11.39 amps at 300 g thrust, but what voltage,
and which prop does best?

I want to run mine in a tube, so there is some tip flow efficiency, some drop-off due to the motor blocking flow, and the motor supports,
, the wall surface drag, and some Coanda gain if I have a nicely rounded inlet.

I will look for some props with square tips.
3 blades should be sufficient, as the motor will just slow down with more blades.
Can I go to 4 inch blades and cut the tips off if I want the square tips?

If you look at the last graph it shows voltage so these were tested on 3s. The suffix on the prop sizes denote their make. N= nylon CF= carbon fiber, CFN =carbon fiber nylon which I believe is not actually carbon fiber but a mixed fiberglass and nylon prop, BN = Blunt nose, and BN-cut means they are cut down from full shape props not specifically designed with blunt tips.

Anything with a BN on the end means blunt nose (tips cut off) which are the worst props to use for efficiency as they are amperage pigs. They give nasty tip drag and inside a duct I think they would actually cancel even more lift depending on depth of the duct.

Xjet did a video on how ducting a propeller works as well as the pros and cons to using them. I suggest you give that a watch.

 

[OwenN]

If you look at the last graph it shows voltage so these were tested on 3s. The suffix on the prop sizes denote their make. N= nylon CF= carbon fiber, CFN =carbon fiber nylon which I believe is not actually carbon fiber but a mixed fiberglass and nylon prop, BN = Blunt nose, and BN-cut means they are cut down from full shape props not specifically designed with blunt tips.

Anything with a BN on the end means blunt nose (tips cut off) which are the worst props to use for efficiency as they are amperage pigs. They give nasty tip drag and inside a duct I think they would actually cancel even more lift depending on depth of the duct.

Xjet did a video on how ducting a propeller works as well as the pros and cons to using them. I suggest you give that a watch.

I already watched the video. Ducted props usually have pretty square tips.

If the tests were 3s, then it should do a 3 bladed poly prop on 4S in a duct. - the only real con I saw is that the coanda lip is no good on a quadcopter. Otherwise the correct blunt tip prop works good.

 

[OwenN]

This is my favourite. By Digital I presume they mean PWM.! Not uart + power supply, or some other scheme. Dimensions scaled approximately. View attachment 186920
1:1 scale drawing.

The dimensions given by this site were wrong!

It is actually 23x12x24.5 and 14.8 g, about a third smaller. The price is better, too. They included internal pictures, too.
Those are some really tiny ballraces!
It is really tiny! about the same size as a standard mini servo.
I shall now draw up my motor mounts in full scale.
It should be rugged enough to stand up to the prop vibration.
The servos shown on the other pictures seemed a little bigger than this one?

 

[PsyBorg]

I already watched the video. Ducted props usually have pretty square tips.

If the tests were 3s, then it should do a 3 bladed poly prop on 4S in a duct. - the only real con I saw is that the coanda lip is no good on a quadcopter. Otherwise the correct blunt tip prop works good.

Good luck on your project mate. Did my best to get you the info you requested. Sorry I was no real help

 

[CampRobber]

Anything with a BN on the end means blunt nose (tips cut off) which are the worst props to use for efficiency as they are amperage pigs. They give nasty tip drag and inside a duct I think they would actually cancel even more lift depending on depth of the duct.

I think in general ducts do actually play well with blunt nose props. Basically you need some design consideration to deal with tip vortex, and you can either taper it out to minimize the vortex, or duct it and totally eliminate the vortex. But I think at model airplane RNs it's very easy to build a duct where the drag due to wetted area greatly exceeds the efficiency gains due to ducting the prop.

 

[OwenN]

Good luck on your project mate. Did my best to get you the info you requested. Sorry I was no real help

You have done well to find information I couldn't. You must be a real search engine whizz!

I think ducting on a model is generally only done for appearance.
For most real life aircraft, they are also of no practical use. The weight increase generally cancels out any gain in efficiency.

Some quirky prototype aircraft have ducts or u-shaped wings, but it hasn't caught on.

Possibly some vertical lift aircraft with artificially small rotors have used them for reasons of compactness.

I see a lot of electric prototype aircraft use them as a replacement for heavy motors or gearboxes.

They can then spin many small propellers faster, then try to claw back low speed thrust lost by doing this.
Even NASA is at this game.

At speed, it doesn't matter, as you are governed more by the propeller pitch speed.

However, you don't want to replace propeller size with excess air jet velocity-unless you have a jet engine and want to go really
fast.