Nimbus Tricopter VTOL

ArduPlane VTOL Plane
99

Graham,

You do indeed have a very large area to map! I assume that you have considered using just an APM plane? Granted, these have their own set of problems like protecting the payload and requiring a landing area, but the efficiency and weight will be better without copter features. Since the area is so large, maybe a roadway exists for temporary landing strip. The FireFLY6 Pro can do up to 243 hectares per flight but it is more expensive. Anyway, I’m just spit-balling here and now understand your needs.

Atico,

I’ll graph my three motor outputs in hover mode and post it to see how much the rear motor is working. I suspect that it works less than the front motors as the triangle is not symmetrical. I’m currently using the 14x5.5 t-prop.

Rafael,

Welcome to our Nimbus VTOL group! My hope is that others like you join in to help form opinions on various issues and solutions. Sometimes this forum can be very quiet!

There are several reasons why your Nimbus oscillated upon return to hover mode. Initially, I would suspect a PID issue or not being pointed into the wind. Did you test the hover mode in various conditions? Do you have the weathervane feature enabled? Can you post your .BIN file from the flight where it oscillated?

Cheers!

100

Yes, we have a Arduplane (the Eve 2000) but launching and landing amongst hundreds of citrus or macadamia trees isn’t fun and most of these farms have few or very rough tracks and landing can be a real issue. Hence the Nimbus.

101

Graham,

It sounds like you need a Mugin. They range in size from 2930mm to 4700mm wingspan. The quadplane design would be more stable than the tricopter. The frame cost is beyond my hobby budget but it keeps me dreaming…

2930mm-Mugin-UAV-Plane
2930mm-Mugin-UAV-Plane.jpg738×553 384 KB

1 Like
102

Here is the graph of my three motor PWM settings in QLOITER mode. The two front motors (in red and green) are around 1577 and the rear motor (in blue) is a bit higher at 1670. My current setup is using the following components. It might be interesting for me to try a 15x5.5 or 16x5.5 prop in the rear to see how much the graph changes.

The FoxTech Nimbus VTOL V2 setup has changed several times but currently uses this setup:

  • 2x Foxtech 3520 KV520
  • 1x Foxtech X5008 KV330
  • 1x Hobbywing XRotor 40A ESC(no BEC)
  • 2x Hobbywing XRotor Pro 50A
  • 1x Pair 1380 Wooden Propeller
  • 1x 1755 MARKII Matte Propeller

6BIN3throttles
6BIN3throttles.jpg963×568 99 KB

103

Greg, good contribution.
It would be interesting to compare if Graham post current with the 1655 .
I think one 1455rear propeller (4112 400kv) has less performance.
it can also help to slow down the rear engine

104

Maybe you might be better off converting a Skywalker X8 similar to what Vertical Technologies did. Although their underlying firmware is PX4 not ArduPlane. It’s “crude” but efficient with a single FW motor.

Good luck.

105

Atico,

I ordered a set of 16x5.5 carbon t-props today from GotHeliRC.com. It will make an interesting comparison. My setup will then match the original FoxTech V2 setup. They then changed their rear motor and prop again to X5008 KV330 with 1755.

I think original FoxTech V1 used the following combination which should match Graham’s setup.

  • 2x Sunnysky 4112 KV485 (front)
  • 1x Sunnysky 4112 KV400 (rear)
  • 1x Pair 1380 Wooden Propeller
  • 1x 1655 MARKII Matte Propeller(CW)
106

In my opinion this last alternative (x5208/340 & 1755) seems disproportionate to me, I think it is better option 4112/400 & 1655 but combined whit 3530/520 & 1380 front motor

107

Greg, I did a hover test this morning. The two front motors mean are about 1425 and the rear 1365 so opposite to yours, rear doesn’t seem to be working that hard.

NimbusHoverServoOut
NimbusHoverServoOut.png1549×972 27.3 KB

My hover current on the other hand seems quite high, average 58A during the hover period. This is with a new Tattu 6S 10Ah pack and AUW of 4.2kg (9.25lb).

NimbusHover
NimbusHover.png1549×972 18.8 KB

What’s your weight?

108

My parameter file

NimbusVTOLafterREinstall.param (17.2 KB)

109

Hi Graham,

I can see the amount of work done by the rear motor is partially tied to the CG. If my memory is correct, you are using the Foxtech V1 VTOL so your front motors are lower Kv and different than mine and you are using a rear 16x5.5 prop. I am still waiting for my 16x5.5 prop to arrive.

I haven’t weighed my Nimbus VTOL yet so all I can say is that I have no payload and the CG is 100mm from the Leading Edge. I can weigh it this weekend.

The difference in our current measurements is odd. I am using a calibrated Mauch Power Module. What Power Module comes with the Foxtech V1 model? Perhaps the Power Module is not as accuate (like the 3DR version) or you have included your payload?

Cheers!

110

My 1655 prop arrived and my first reaction was, “Now that’s a prop!” :slight_smile:

The weather was pretty nice today so I installed it and did a quick hover test in the backyard using QSTABILZE mode. The Nimbus hovered nicely with the new prop. I had a near full charge on my Multistar 6s 10AH Lipo pack which may account for the slightly lower C5 and C6 front motor numbers. This time they were 1524 compared to the last test at 1577. The rear motor C8 was indeed lower with the new prop at 1588 compared to 1670 on my previous hover test. This appears to be a good change.

The current graph goes up and down a bit as I feathered the throttle in QSTABILIZE mode. I took a near high reading of 29amps to multiple with the 6s voltage of 23v to get a hover power of 667w. This was close to my guess of around 700watts without a payload which is similar to the FireFLY6 wing.

This was also my first hover test after finishing the internal wing wiring with 6v BECs. It was nice to just press the wing halves in place without manually connecting wires!

1655Prop3throttles
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1655PropHoverPower
1655PropHoverPower.jpg963×568 104 KB

111

good test, good comparation. >>> 1,6 A less

It would be nice to know the weight of your nimbus to compare it with the Graham test

112

Ahh, yes, I promised to weigh my Nimbus VTOL. So here it is:

  • Multistar 6s 10AH Battery with Plywood Plate = 43.6oz (1236g)
  • 1 VTOL wing = 26.5oz (751g)
  • 1 VTOL wing = 26.5oz (751g)
  • Both tails = 3.35oz (95g)
  • Nose with AS Sensor = 3.45oz (98g)
  • Body with Landing Legs = 44.8oz (1270g)

Total weight without payload = 148.2oz (9.26lb)(4201g)(4.2kg)

113

adding one minicamera with pan tilt in nose and a second camera = 4500-4600 gr

114

Now the question is what will be the performance of a Sunnysky X5208 KV330 or T-Motor MN5208…

anyway the flight Q should not be more than 10 seconds before the transition

115

I was going through some setup parameters and noticed that Graham had this:

AHRS_EKF_TYPE = 2

and I had this:

AHRS_EKF_TYPE = 3

This controls which NavEKF Kalman filter version is used for attitude and position estimation. Is there a difference?

116

I found this: https://github.com/ArduPilot/ardupilot/pull/5336 which explains a bit. I also compared your params to mine and there are quite a number of differences, some of which I presume, differ due to Foxtech’s testing and development phase.

Would love to know the reasons behind some of the changes.

117

Good link, thanks, Graham!

I have just compared the differences between our param files. Here are the critical ones below. Since you have flown yours, all the non-Q PIDs from yours should be used. I also need to enable the weathervane features, etc. I would still love to see a V2 .param file to see what the wind resistance changes were.

Differences from Graham’s PIDs

AHRS_EKF_TYPE,2
ARSPD_FBW_MAX,18
ARSPD_FBW_MIN,11

LAND_DISARMDELAY,10

LIM_PITCH_MAX,2000
LIM_PITCH_MIN,-1500
LIM_ROLL_CD,4500

MIXING_GAIN,0.5

MNT_RC_IN_TILT,0

PTCH2SRV_D,0.04
PTCH2SRV_FF,0.4
PTCH2SRV_I,0.15
PTCH2SRV_IMAX,3000
PTCH2SRV_P,0.7
PTCH2SRV_RLL,1.15

Q_ANGLE_MAX,3000

Q_ASSIST_ANGLE,30
Q_ASSIST_SPEED,0

Q_TILT_MAX,60
Q_TILT_RATE_DN,50
Q_TILT_RATE_UP,200
Q_TILT_TYPE,2
Q_TILT_YAW_ANGLE,13

Q_TRAN_PIT_MAX,10
Q_TRANS_DECEL,2
Q_TRANSITION_MS,3000

Q_VFWD_GAIN,0.05

Q_WP_RADIUS,500 (now 200, use 400?)

Q_WVANE_GAIN,0.2
Q_WVANE_MINROLL,2

RLL2SRV_D,0.1
RLL2SRV_FF,0.4
RLL2SRV_I,0.2
RLL2SRV_IMAX,3000
RLL2SRV_P,1
RLL2SRV_RMAX,0

WP_LOITER_RAD,80

WP_MAX_RADIUS,0
WP_RADIUS,10

YAW2SRV_DAMP,0.08
YAW2SRV_IMAX,3000
YAW2SRV_INT,0.3
YAW2SRV_RLL,0.8
YAW2SRV_SLIP,0

118

My changes in bold (corrections/suggestions welcome):

AHRS_EKF_TYPE,2
ARSPD_FBW_MAX,18 - (good max speed for this type/size of plane)
ARSPD_FBW_MIN,11 - (Just above the stall speed of 10m/s)
LIM_PITCH_MAX,2000 - (no need to pitch up more than 20°)
LIM_PITCH_MIN,-1500 - (no need to pitch down more than 15°)
LIM_ROLL_CD,4500 - (Limits bank angle for heavy plane)

MIXING_GAIN,0.5

MNT_RC_IN_TILT,0 - (for our camera gimbal)

PTCH2SRV_D,0.04 - (increased for tighter tune)
PTCH2SRV_FF,0.4
PTCH2SRV_I,0.15 - (increased for tighter tune)
PTCH2SRV_IMAX,3000
PTCH2SRV_P,0.7 - (increased for tighter tune)
PTCH2SRV_RLL,1.15 - (keeps nose more level in turns, less loss of height)

Q_ANGLE_MAX,3000

Q_ASSIST_ANGLE,30
Q_ASSIST_SPEED,0

Q_TILT_MAX,60
Q_TILT_RATE_DN,50
Q_TILT_RATE_UP,200
Q_TILT_TYPE,2
Q_TILT_YAW_ANGLE,13

Q_TRAN_PIT_MAX,10 - (default of 3 resulted in a worrying dip/loss of altitude during transition)
Q_TRANS_DECEL,2
Q_TRANSITION_MS,3000 - (changed from 5 secs, plane transitions quickly so 5 secs seemed too long)

Q_VFWD_GAIN,0.05 - (Wind resistance in hover)

Q_WP_RADIUS,500 - (looser waypoint radius)

Q_WVANE_GAIN,0.2 - (wind vane enable)
Q_WVANE_MINROLL,2 - (activate on 2 deg of roll)

RLL2SRV_D,0.1 - (increased for tighter tune)
RLL2SRV_FF,0.4
RLL2SRV_I,0.2 - (increased for tighter tune)
RLL2SRV_IMAX,3000
RLL2SRV_P,1 - (increased for tighter tune)
RLL2SRV_RMAX,0

WP_LOITER_RAD,80 - (good distance for QRTL transition, allows plane to slow down enough)

WP_MAX_RADIUS,0
WP_RADIUS,10 - (more accurate waypoints, especially with flying grids)

YAW2SRV_DAMP,0.08 - (tuning to stop tail wag)
YAW2SRV_IMAX,3000
YAW2SRV_INT,0.3 - (tuning to stop tail wag)
YAW2SRV_RLL,0.8 - (tuning to stop tail wag)
YAW2SRV_SLIP,0

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