Mollie MultiWii Bicopter(s)

justk1w1 · Post by **justk1w1** » Fri Oct 19, 2012 12:30 am

Using a 10dof multiwii board which has itg3205 and bma180 .. just really need to know when u pitch forward what direction is output from both. I.e. pitch forward gyro acc and mag positive on multiwii GUI.

What rotations do you have I.e. left CCw right cw.

Thanks

copterrichie · Post by **copterrichie** » Fri Oct 19, 2012 12:36 am

Sorry Justk1w1, I am just not understanding what you are seeking. How about a picture or a video?

justk1w1 · Post by **justk1w1** » Fri Oct 19, 2012 2:33 am

In multiwii config screen under the real time data .. when you pitch Mollie forward what response do you see. I.e. gyro pitch and acc pitch go positive or negative. I seem to have things working in roll and yaw, but if you could kindly confirm these actions also. The setup for the bicopter is heaps harder than that for quad. Thanks for all your help

justk1w1 · Post by **justk1w1** » Fri Oct 19, 2012 12:46 pm

CopterRichie:

Thank you for all your help - much appreciated.

All airbourne now, which was the main task - the control seems to be pretty good and not getting any oscillation in pitch. I had to configure the PITCH Sensor orientation so that both ACC and Gyro provide a negative result when the copter is pitched forward. This is the opposite to the sensor orientation for a quad copter which has to have both positive if the copter is pitched forward. Also had to change the COG a little to help the initial stability. Still need to fine tune the PIDs a little more, as it drifts around a little bit - went back to the standard props (until I can get bigger, stiffer three blades). Now just need to sort out my MAG issue and all is looking really good - a little rough but this was just a first prototype and now I can play with the design. This probably worked out cheaper than building a quad and looks like it's going to be a great camera platform. I used an old HK450 frame and about $6.00 of aliminium u tube.

Going to look at upgrading the motors as they are running a little hot, so I guess they are a little under powered and I'm looking at adding more sensors - sonar radar (which I'm working on at the moment), GPS, optical flow, OSD and FPV camera equipment.

copterrichie · Post by **copterrichie** » Fri Oct 19, 2012 12:54 pm

Very interesting and Congratulations. I personally don't use a MAG for heading holding, I just increase the I and D values for the YAW and my copters hold heading very well. I know a MAG is required for RTH etc, but for right now, I just don't use them.

Post a video, maybe I can share some PID tuning tips.

copterrichie · Post by **copterrichie** » Sat Nov 03, 2012 7:55 pm

http://www.youtube.com/watch?v=GHoeGdqhdtU

The time spent on the flight simulator is starting to pay off. When the lady appeared with her little doggy, I brought Mollie in close and called it a day.

NikTheGreek · Post by **NikTheGreek** » Sat Nov 03, 2012 8:50 pm

WOW......

vpb · Post by **vpb** » Thu Nov 08, 2012 7:16 am

hehe i like your smooth "curve", do you use baro when training, copterrichie?

copterrichie · Post by **copterrichie** » Thu Nov 08, 2012 1:30 pm

vpb wrote:hehe i like your smooth "curve", do you use baro when training, copterrichie?

Thank you vpb, MiniMollie only has a MPU6050 (Gyro/Acc), so there is no baro on her. I am an avid user of the Throttle Curve available in the MWC 2.1.

tovrin · Post by **tovrin** » Sat Nov 10, 2012 4:48 am

Ritchie, I'm building a bicopter because i think its the better design for front mount camera usage. I have a series of motors already i want to use (because i already own them) but want to verify this is even reasonable.

i have 4 (25 AMP) 2830 750kv (9-12 inch props) motors id like to use as my main (2up and 2down), and a set of 2 (8 amp) 1600 Kv micro motors (3blade 7inch props) id like to use for the yaw control. (i actually have 4 of these, but dont have a PPM RX, so i dont think i can use those, yet...)

the point im concerned about is the Kv difference but i assume its not an issue since the rear motors are strictly yaw/pitch control, and the added resolution would be beneficial to camera action if i keep the vibrations out.

copterrichie · Post by **copterrichie** » Sat Nov 10, 2012 5:05 am

I am kinda confused here, sounds like you want to build a V-Tail and not a Bicopter. A bicopter only requires two motors/Props and two servos.

tovrin · Post by **tovrin** » Sat Nov 10, 2012 5:18 am

yes, im sorry, VTail is accurate. I dont plan on using any servos.

copterrichie · Post by **copterrichie** » Sat Nov 10, 2012 5:23 am

tovrin wrote:yes, im sorry, VTail is accurate. I dont plan on using any servos.

There is a reason why the forward arms of the sweptback are positioned as they are, the Center of Thrust can easily be matched up with the Center of Mass(Gravity). Therefore, you can use any KV motors you want, just vary the position of the forward arms to match.

http://www.ehow.com/info_12032830_cente ... -mass.html

tovrin · Post by **tovrin** » Sat Nov 10, 2012 5:24 am

good point, thank you.

copterrichie · Post by **copterrichie** » Wed Jan 09, 2013 9:19 pm

Here my newest multi rotor copter named Mollie-VTOL. She is modeled on the Doak VZ-4, the airfoil made using ExperimentalAir's Dollar tree foam backing board techniques. The Flight controller is The Flip MWC FC. -MPU6050w and MWC version 2.1 Firmware with Bicopter mixing.

The original design used 10" 3 bladed Master Airscrews however, I had to adjust them to 12" and upgrade the motors to RCTimer 3536-9 for the additional lift. She weighs in at 1.9kg without the ducts. Now I have to find another suitable material to make the ducts from.

http://www.youtube.com/watch?v=FmVYrxGk0Ug

vpb · Post by **vpb** » Thu Jan 10, 2013 7:55 pm

Big mollie

!
Doak VZ-04, http://www.youtube.com/watch?v=gRIZ8qt18JY, since 1958

.

Wait for Mollie air-plane mode clip, Copterichie!

copterrichie · Post by **copterrichie** » Thu Jan 10, 2013 8:01 pm

Thank you for sharing the Doak video, I had not seen that one but many similar ones. IMO, it was a great design and concept but as we know, Politics always play a factor in these issues.

Was going do some forward flight testing today but the winds are too high.

copterrichie · Post by **copterrichie** » Wed Jan 30, 2013 8:41 pm

We are making headway, Just installed and tested a weight shifting (CG) device to counter the pitching problem Bicopters are known for. In fact, I am going to retrofit this device on both Black and Mini Mollie.

http://www.youtube.com/watch?v=iQ_N94XRM1Y
http://www.youtube.com/watch?v=SM6JbGpdDv4
http://www.youtube.com/watch?v=tPHMd67GP4U

NikTheGreek · Post by **NikTheGreek** » Wed Jan 30, 2013 10:39 pm

Mollie is getting better and better..

copterrichie · Post by **copterrichie** » Wed Jan 30, 2013 11:28 pm

Thanks Nik,

vpb · Post by **vpb** » Thu Jan 31, 2013 3:18 am

I see that you have an endless love to bicopter

copterrichie · Post by **copterrichie** » Fri Feb 15, 2013 4:36 am

Got around to doing the first park test with the new weight shifting mechanics, much improved over the last park test. She still requires some PID tuning and some YAW refinements but she is progressing nicely. I am a very slow builder and never rush anything because I don't have allot of resources. One crash can set me back months, so I take my time making sure each step are complete.

I am very hopeful the next Park test will be with the props rotated to about 20', not sure if I will attempt this rotation in air or do a running take off. I am almost sure it will be the rolling takeoff because I can shut down quickly if things do not go as planned.

http://www.youtube.com/watch?v=MzIrX_FKSU0

NikTheGreek · Post by **NikTheGreek** » Fri Feb 15, 2013 7:19 am

Better and better every time !!!

copterrichie · Post by **copterrichie** » Sun Feb 17, 2013 5:30 pm

Rolling Takeoff Test

Instead of powering down and bring her to rest on the grass, I made a snap decision to turn her about and try to land on the baseball diamond. Damage was minor, bend motor mount pin which I knew was the weakest link from the onset in the system. A few repairs and will can resume testing.

http://youtu.be/W8y6NLdDkO4

copterrichie · Post by **copterrichie** » Wed Feb 27, 2013 11:01 pm

I had gone to the park this morning hoping to get in a forward flight test however, I erred in the mixing table noted during the per-flight routine. So I aborted the test. Not wanted to waste the valuable sunshiny day, I decided to get in some Pop testing. I first tried some APC 15 x 10s that were cut down to 13 inches but that was a total failure. They were just too much out of balance even after I had done a static balancing to them. Next I tried some APC 12 x 3.8 and they look very impressive. They generated more noise but they also seems to equal the Master Airscrews in Thrust and lifting abilities. The reason I will not use them is because of the hub measurements. I will look into getting some Thin Electric for testing. During this round of testing, I am noticing this copter seems to like hovering with it's tail down a few degrees. level and she wants to move rapidly which is what she is designed to do, just a learning curve for me. Upon landing, the motors were warmer that I expected so I will have to also look into motors with a larger bell size and maybe more poles. I do not foresee being able to use a 5S battery with them.

Flight Test: http://youtu.be/QPQcQD3_7Og

Flensburger · Post by **Flensburger** » Sat Mar 16, 2013 2:21 pm

Hi.

As you know, i like do build the same as Mollie. The wight is around 1,8kg? Which motor is installed?

copterrichie · Post by **copterrichie** » Sat Mar 16, 2013 2:24 pm

Flensburger wrote:Hi.

As you know, i like do build the same as Mollie. The wight is around 1,8kg? Which motor is installed?

At 1.8kg, you will need a motor in this class or larger, I am not suggesting this one, only offering it as an example: http://www.rctimer.com/index.php?gOo=go ... oductname=

Anything less and they will run hot.

Flensburger · Post by **Flensburger** » Sat Mar 16, 2013 2:38 pm

possible. tested some configurations with http://www.ecalc.ch/xcoptercalc.htm?ecalc&lang=en

Brand Motor 2 X Tork A Time Power Lippo wight
Turnigy T3632-1200 4S 8x4x3 2060 29,5 11,4 ~500W 4S 99g
RC-Timer A3536-6 1250 4S 8x3x3 1889 30 11,1 500W 4S 102g
RC-Timer BC3536-6 1250 4S 8x3x3 1889 30 11,1 500W 4S 102g

copterrichie · Post by **copterrichie** » Sat Mar 16, 2013 2:42 pm

a 8" prop is kinda small for a copter of 1.8kg. I use 12" and 13" props for my later bicopters.

Flensburger · Post by **Flensburger** » Sat Mar 16, 2013 7:12 pm

copterrichie wrote:a 8" prop is kinda small for a copter of 1.8kg. I use 12" and 13" props for my later bicopters.

Thats the question. Based on the online calculation tool, two Turnigy T3632-1200 on 4S 8x4 3 blade can lift off 2000 gramms. But i haven't tested and searching a similar project.

By the way, nice project your Mollie.

copterrichie · Post by **copterrichie** » Tue Mar 19, 2013 6:27 pm

Now I need to focus upon designing and building the ducts and transitioning to forward flight. I should sometime this week, pick up some fiberglass and resin to begin experimenting with forming some light weight aerodynamic ducts. As the saying goes, nothing ventured, Nothing Gained!!

http://www.youtube.com/watch?v=Q-DdMadNxeA

copterrichie · Post by **copterrichie** » Wed Mar 27, 2013 5:01 pm

Introducing Mollie Duct Fan. I don't believe at this time, she will fly as well as Mini Mollie because she will be under powered. Mollie Duct Fan is more of a novelty at this point.

copterrichie · Post by **copterrichie** » Fri Apr 05, 2013 12:35 am

Just a little update on the Mollie Duct Fan (MDF) Build, servos installed but awaiting arrived or some metal geared servos. The ones shown are for testing only. According to my calculations, the two EDFs should supply 1kg thrust each on a 4S battery. This should be pretty to get MDF off the ground and into the air. Now, how well will she fly?

copterrichie · Post by **copterrichie** » Mon Apr 29, 2013 1:10 am

Just stating my opinion here, a Bicopter is not for everyone, they are not the easiest aircraft to fly but they can be very rewarding both to build and fly. Unlike other copters, a Bicopter is very unforgiving when it comes to battery placement and in my opinion, is where many copter builds fails. This position is so critical, that once I have the battery placement correct, I don't like changing the pack with a fresh pack but will recharge the pack on the copter. With the newly developed weight shifting mechanics(WSM), this is not so much of an issue any more for me. However the WSM adds additional weight and complications I believe many would prefer not to undertake. In the following video, the battery is just a tad bit to far to the rear making the copter tail heavy. However, not enough to create a wild pitching experience that I have see others experience.

copterrichie · Post by **copterrichie** » Mon May 06, 2013 2:34 pm

This is the very first attempt to fly Mini-Mollie on a fairly windy day, she fared very nicely. I did not attempt any fancy maneuvers, just maintain heading and altitude. This flight was more about learning the flight characteristics this copter and building personal skills. I was worried at the onset about flying in windy conditions but now I see that concern was in vain.

Like me or hate me, there is little doubt as to how well my unique copters are constructed and their ability to fly. :mrgreen:

NikTheGreek · Post by **NikTheGreek** » Mon May 06, 2013 7:08 pm

She looks stable

copterrichie · Post by **copterrichie** » Tue Jun 04, 2013 2:13 pm

Mini-Mollie II

Did some more trail and error testing, this time using smaller Props Master Airscrews 7x6 3 bladed because the motors were running a bit to hot for my comfort zone. Now the motors are lukewarm to the touch which indicates, less wasted energy. I have some APC 8x6 on order and will test them upon receipt. I am very amazed at this little copter because she weighs in at 1.6KG but yet has pretty of power. Going to upgrade her motors to a 35mm bell (present are 28mm bells) in the near future and reinstall the Master Airscrews 9x6.

copterrichie · Post by **copterrichie** » Tue Jun 04, 2013 2:18 pm

FYI, there is a DIRECT Relationship with Motor KV, Prop size and PID Settings. Changing Motor KV or Props has an major impact upon the PID settings.

copterrichie · Post by **copterrichie** » Sun Jun 09, 2013 5:36 am

Here is a video of Mini-Mollie II all very close to her final PID settings. She needs a few more points adjustment to the Pitch axis, the Roll axis is pretty solid at this point.

copterrichie · Post by **copterrichie** » Wed Jul 03, 2013 6:12 pm

In a quest to improve Mini-Mollie I's forward flight speed, I tried a number of experiences to no real avail. She is as good as it gets in the present OAT Bicopter format. I changed the angle of the tail to 30 degrees and as the forward speeds increased, the tail would drop even more. So I returned the angle to about 10 degrees and moved the battery forward about a 1/4". This improved the forward speeds slightly. I am proud of this little bird and will fly her as is from this day forward, no more modifications.

copterrichie · Post by **copterrichie** » Thu Jul 11, 2013 11:01 pm

Installed the newly purchased BC3530-8 1700KV motors paired with Master Airscrews 9x6 3 bladed props. Much improved in both handling and response. Much quieter also in comparison to the 7x4 Thin Electrics I was using prior.

Made two really good passes here, Looks as if we have a little speed daemon.

copterrichie · Post by **copterrichie** » Sat Aug 17, 2013 5:49 pm

I wanted to know how the Weight Shifting Mechanics (WSM) would work on a traditional OAT Bicopter so I removed the variable pitch system from Black Mollie and installed the WSM. In this test, I did not attempt any speed records because this test was more about observing the flight characteristics and how they had changed because of the WMS. My initial conclusion is, very stable in forward flight but will never be as fast as Mollie II (FAAT) bicopter. However, I have noted areas of improvement that will increase her airspeed, just how much is yet to be determined. The real benefit however is a very stable level flying aircraft for aerial photography.

Sp1k3 · Post by **Sp1k3** » Fri Dec 20, 2013 10:15 am

Hi copterriche
I would need your code as Im working on a similar project.
But I would like to have the code for a tricopter with the motor in the back as well but with the 2 servos like yours. Im using version 2.3.
Could you help me that? I think that your code at the moment only involves 2 motors.
Thanks
Sp1k3