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Posted by askman | Jun 08, 2014 @ 11:30 PM | 2,743 Views
Last few weeks, I've been very busy trying to improve efficiency of multicopter while retaining good wind performance. I've spent lot of time on ecalc and real life testing using my y6 with 2216 motor. I love how well Y6 flies and handles wind, but it has efficiency penalty . Ecalc is also great tool for finding rough estimate. I wanted to set this unit to fly about 10min with reserve carrying my gimbal. Coaxial multicopter generally has 10-30% efficiency loss compared to flat multicopter From what I've been studying though, slower prop rpm is generally better for efficiency drop . One test I've seen seem to see 10-15% drop at 3000 rpm. (can't find where I saw that test though when I looked for it again. I've also used higher pitched prop on the bottom which has been shown to help efficiency a bit.


The key to efficiency has been Larger Prop turning relatively slow (2-3000rpm) with at least 50% throttle level. My test multi had sunnysky 2216-800kv motor on my Y6 using 10" prop and 4S 5000 pack at about 3kg. I have lot of experience with this setup. Using Ecalc, you get 8min hover flight time at 6.5g/w. with Y6 having bit of efficiency penalty, it corresponds well to my near 7 min actual flight I used to get out of pack. (normally flew for 5min for 3500mah) Going to 13" prop and 3S5000 pack. ecalc basically gave me same 8 min flight time at 2870gm (smaller pack weight difference) at 8.5g/w...Continue Reading
Posted by askman | May 18, 2014 @ 03:24 AM | 11,970 Views
Several of us were discussing the portable multicopter for long duration flight with gopro gimbal. I've always flown quads, hexas and y6 but never a tricopter. just somehow, I never managed to build one mostly because I've always thought servo was added complicaton and my favorite multies were y6 anyway. one of the motivation was that I really like y6 and I was hoping that i would gain some of the benefit of Y6 without too much penalties

In the past, tricopter was popular because it could be built using cheap rates gyro without any special board. Also, motor/esc was more expensive compared to servo. After some research, may tricopter owners also stated that tricopter flew more like airplane or heli compared to true multicopter which tend to be very axial in turns. As long time heli flier, I really like how smooth heli can be flown, so, I decided to go for building a 15min flying tricopter with gopro gimbal and video downlink system using APM 2.6 flight control using 3.14 firmware.

I had few Dualsky 5010-9, which is 390kv motor with 15-4 prop, tunigy trust 6S esc flashed to bs.fet (simonk) , Tower Hobby TS160 servo (standard size digital cheap servo mostly because I had a new one and wanted to try cheaper, just to see if it will fly ok with it. had some nicer servo as backup just in case ) initially setup to run at 5v, but since changed to 6v. Since portability was desired, I needed the arms to be foldable. anyway, it took...Continue Reading
Posted by askman | Feb 08, 2014 @ 12:09 AM | 5,728 Views
unlike lot of part of the country, we don't get a lot of snow in my neck of the wood, so when we had our big winter storm, I couldn't resist but get a video of it.

winter storm 2014 from air (2 min 59 sec)

Posted by askman | Sep 26, 2013 @ 07:27 PM | 4,008 Views
Myself and my friend Kenji had a great pleasure of being able to do a indoor aerial video shoot of the Oregon State capitol building with permission from the Legislature.

This event got its start with pending UAV/UAS laws that were being debated by the state senate. While we were at the hearing (which both of us testified) we also presented them with sample videos that we shot. Soon after, Kenji did a nice outside video of the capitol building, which we presented to the legislatures and they gave us permission to also do an indoor shoot. This following is the product of that shoot. Kenji did a great job of editing the footage.
This was shot mostly in 1080p60 medium mode. We ended up with about 30min of footage in about 2 hour shoot. distilled down to what is in this video.

Tour of the Oregon Capitol (2 min 57 sec)



We managed to make arrangement with the facilities to be able to shoot on saturday when building was closed to public. Initially, the facilities managers were bit concerned but after nice discussion about the capabilities of the gear and a walk through, we allayed any fear that was present. Being professional, knowlegeable and experienced really is important in managing with people. Due to nature of this being indoor, we limited ourselves to smallest rig we had available. I was the indoor pilot as I had much higher experience in flying.

On the day of the flight, I brought my phantom with 3 axis stablized gopro...Continue Reading
Posted by askman | Aug 13, 2013 @ 10:04 AM | 4,404 Views
I get contacted for yaw/roll coupling issue of gimbale a lot. there are couple solutions:

1) Do a 6point calibration of accelerometer. this usually fixes this. Earlier version of code required this everytime you upgraded firmware.
2) in 2 axis gimbal, you can connect flight control gimbal output to the input of alexmos. this is not an option for 3 axis though.


Alexmos issues

1) move the imu wire away from the motor.
2) add ferrite cored to the imu wire
3) I've had several people have issue with input connection causing problems. for pitch, remove the power wire . verify setup is correct




Video Downlink:

I've been having lot of fun and use out of my pirate eye setup. This is single eye solution for video downlink which I prefer as I can keep an eye on the vehicle LOS. I use 200mw 5.8ghz with simple osd (just voltage and time)
I have mounted the receiver and battery (velcro) to my outback hat for simple compact setup. even with stabilized video only, I can fly safely as I can watch the vehicle via LOS

this is video of my phantom with 3 axis gopro gimbal and video downlink with video out from stablized gimbal.(1295gm and 7 min on 2200mah 3s pack) I would have issue with doing this completely via goggle as I would lose the vehicle orientation. DJI OSD has small artificial horizon but they weigh more and cost more. with gopro, you get video on time so all I needed was voltage on my osd.

3axis phantom gopro black 1080p medium mode (5 min 53 sec)

Posted by askman | Jun 17, 2013 @ 01:50 AM | 5,607 Views
To get peak performance out of AG DD gimbal, ,you will need good setup and possibly tweaking of the tuning. I will be using this blog to update the latest setting and setup technique. of course, be sure to read the software setup guide from tppacks, which will be updated in the future with more information.


as stated in the guide good performance is all about
1) good balance
2) friction free setup
3) good balance.
4) tuning

without near perfect balance and smoothness, you won't get good performance. first sign of improper setup is bad buzzing. this occurs when motor is trying to compensate for small positional error, but can't and create a fine oscillation. The main cause is either due to balance or friction. (and rarely resonance oscillation caused by motor vibration)

Mechanical friction:

let talk about friction first. In most adjustable gimbal, you get friction when things are out of parallel. for example, the yoke arms is not parallel in both vertical and horizontal view. the gimbal should move freely and easily. this should be fairly easy to test and fix. mostly visual and moving the camera plate should give us clue.


Balancing

I start with roughly balancing the roll with camera on. lock the roll down once this is done.

I do the pitch balancing next. Pitch balancing is critical with camera at all the angles that camera will face. I start by setting up the camera balance with lens facing down....Continue Reading
Posted by askman | Apr 09, 2013 @ 03:13 AM | 7,013 Views
Lately, there has been lot of new gimbals with Direct Drive, thanks to work done by people like Alex and others. Of course, the first group that made DD servo available to mass has been DJI. They truly deserve accolade and they are still the performance champ.

First of all, I would like to clarify that Servo is nothing more than motor with positional feedback. Even the DD gimbal using motors gets its positional feedback via IMU that is mounted on the gimbal. Whether they are DD or not, they are all Servos. I know that people like to equate servo with typical hobby servo, but that is not true.

At least in hobby realm, for long time, we were limited by available motor (brushed), size requirement and available voltage(typically 5v due to transistors) While speed was nice, it was not as critical as torque and smaller size, so highly geared servos were made, has become standard. In greater motion control industry, servos are used to control many machinery. lot of them are direct drive, while most are belt or gear driven . Some uses screw drive to achieve higher torque/gearing effect. In fact, it is very rare that servo is used in direct drive application unless you need speed more than torque. In our application though, we do get pretty good assist from gravity by having perfectly balanced system, we reduce the inertia down to its frictional component.


anyway, as we all know, acceleration of starting motor depends on...Continue Reading
Posted by askman | Feb 17, 2013 @ 07:09 PM | 6,855 Views
It seems like wind is our nemesis when it comes to doing AV/AP especially with multicopters. I seem to get lot of questions about this, So lets talk about ways to optimize high wind flying.


Like any other RC flight, the key to wind flying is wing loading, or in case of multicopter, disk loading. for high wind, flying wing works really well for airplane while glider type does poorly. In case of multicopters, we need to get our diskloading up for best wind performance. For this, we need to use smaller prop that is really rigid for best performance. You may also need to go higher voltage to gain back some of the loss in lift. The downside is loss of flight time, but if getting that shot is very important, flight time loss can be acceptable tradeoff.

Now, I get asked about what is the best frame for windy flying. My answer is that Y6 is the best. Stacked coaxial props behaves best for yaw, and has apparent reduced disk area so handles wind and high speed the best. You do want the frame to be rigid. The downside of Y6 is reduced flight time of 10-15%. To me, that is acceptable loss of flight time. For smaller multi, I do think quad is definitely better than hexa .

Of course, if you already have to frame, you can maximize windy performance.
1) Smaller prop (that is rigid) at higher rpm is better than bigger prop. Going from 10" to 9" reduces disk area by 21% and will require higher...Continue Reading
Posted by askman | Feb 04, 2013 @ 09:30 PM | 6,990 Views
Let me begin by stating that I am not a video editing expert. but I have had to learn and setup a new machine dedicated to video editing and learn all about it over the last 12 month. I want to at least give basic idea on equipment and software it takes to get reasonable results.

Computer requirement::

Lot of people run Mac/iMac and they do work pretty well at a premium in cost. In general, more cpu power you have, better off you are. First of all, i would recommend Intel processor for video editing. Even latest AMD fx-8350 seems to lag behind core i5-3570 in terms of rendering speed and price is similar to i5-3570k. Just know that editing HD video takes lot of computing power. When I started, I used my old laptop with amd A6 fusion chip (quad core) and it has been really too slow. for example, running video stabilization using mercalli averages 5fps. If you want decent performance, I would recommend minimum of intel Core i5 with 16gb of ram. Luckily, video editing really does not need high power graphics card, so build in 4000hd graphics is adequate. But if you do like to decent preview performance, and run CS/6, it is wise to have decent nvidia card. luckily, cheaper card like gt640 seem to give good result with cuda implementation of cs6. . Dual SSD drive in RAID 0 configuration would be nice, but if cost is an issue, I would recommend dual Western Digital RED 1tb hard drive in RAID 0 configuration as minimum. RED series...Continue Reading
Posted by askman | Jan 08, 2013 @ 05:37 PM | 7,097 Views
Happy New year everyone.

It has been almost a year since I've restarted building selling camera gimbals and now multicopter AP specific frames. it has been good run and we have made lot of progress. We have been very open in our development work and we are continually making improvement to make our products the best it can be.

As we get better result, we've always want bit more performance. It seems like never ending push for performance.

Key to Performances:

1) Use proven system and camera. Unless you are into fiddling and testing different stuff, you can save lot of head ache and issues with using proven setup. This goes for camera, gimbal/controller and multicopter. (as well as props and motors) use multicopter specific esc if you can, as it will help give extra stability.

2) vibration control, vibration control, vibration control. I cannot stress this enough. Especially if you are using camera that is more susceptible to vibration. Early CMOS cameras are really bad for rolling shutter and jello issues.


3) Practice, Practice, Practice. whether it is flying, taking picture or editing, you need so many skills for success that practice is paramount.

4) pick a right tool for the job and practice safe flight rules. sometimes small quad with gopro may be better tool than full rig. Use good common sense.

Now, I will talk a bit about setup. since most of us use DJI controllers, I will...Continue Reading
Posted by askman | Nov 29, 2012 @ 05:54 PM | 8,207 Views
well, It seem like I've been getting this question asked a lot recently with release of my new AP/AV multicopter frames. So I want to spend some time today to discuss the consideration for deciding what size multicopter frame to choose.

When I began my multicopter journey, I started out with spectrolution board. it was first "Affordable" controller at mere 450 bucks and came with 3 axis of gyro and thermal levelling system (similar to fma copilot . OMM (oldmanmike) was using small outrunners with 10" epp props and I was one of the first to use dt700/750 in multicopters. Since we were mostly doing still photos and crude video, the airframe was very simple and crude by today's standard.

fast forward 4 years and now, multicopters have become ubiquitous. With all the variety of choices, it has become more confusing to choose, so I wanted to share some basic criteria.

Much as Hexacopter has been popular in US (this due to certain reasons that has to do with availability of small motor and props more than anything) we find coaxial type of multi does much better in windy situation. In general, quad is no worse than hexa in most cases and cheaper. While lightely loaded hexa will offer some protection against motor outage, this is rarely the case in AP. Also in general, bigger disk area means worse wind performance. That is why we have settled on quad, y6 and x8(both coaxial) form of multi as being ideally suited....Continue Reading
Posted by askman | Oct 02, 2012 @ 11:36 AM | 9,997 Views
It seems like I've been answering lot of question about Jello lately, so, I want to put some basic primer on vibration control today. There is NO EXCUSE to have jello or vibration in your AP/AV multicopter and if you have it, you need to kill it and it all starts at the Source.

PROPS: Lousy balancing of props are the biggest cause of Jello. Cure starts with high quality props and good balance job. here is a good video on prop balancing: I know some prop makers say their props are prebalanced. well, may be good enough for Nitro plane, but not good enough for AP/AV.

prop balancing video tutorial (5 min 5 sec)


In general, larger the prop, more critical it is to balance the prop in both blade, tracking and hub. I've found that sub 10" props are much easier as hub balance gets less critical, but most AP/AV setup requires larger prop. Even Graupner props will need some work in balancing, but usually less so. Why lot of graupners gets used in AP. APC props are notorious for poor hub balance and requires lot of work to get them to perform well. Even my favorite zingers requires balancing (but easier since I can sand down the wood ) Invest in good balancer and learn to balance your props. I've been selling lot of zingers for multicopter AP use, as they do really well in wind flying. not the most efficient, but very stable. I would avoid cheaper nylon props. In general, EPP props are lousy for AP/AV. heck, I don't even...Continue Reading
Posted by askman | Aug 31, 2012 @ 02:31 PM | 9,282 Views
well, we have come up with budget and idea about what we want to achieve with AP/AV. Now, it is time for multicopter selection, and setup.

Now, if you have never flew RC, stop here and go buy yourself a AR drone or Blade MQX as welll as copy of good simulator. get comfortable flying the blade MQX before venturing further. This is good advice if you don't have good RC flying skill and it is stress free way to ease into multicopter.

If you are ready for first larger multictoper. I would recommend F450 frame. ARF kit is affordable way to get into the first serious multicopter. Combined with naza, it makes for good starter ap/av setup.

For AP/AV controlling vibration is paramount to success. Good quality motor and props are very important in fighting vibration.

Motor:

the downside of DJI kit is the quality of the motor. The qc has gone down IMHO from early production, so sometimes you can get motors that cause bad vibration. If you'd rather have an alternative motor, I would recommend sunnysky 2212 /920kv or better yet 2216-800kv motor as alternative replacement, but only after you are over the initial crashing phase. DJI motors are easy to replace and commonly available and can use upto 10" graupners or 9" zingers on 4S . . 2216-800 will turn upto 11" graupner or 10" zingers and on 4S, that is lot of thrust. For cheaper prop. use 8" dji with lighter load practicing....Continue Reading
Posted by askman | Aug 23, 2012 @ 08:14 PM | 11,648 Views
instead of continuing my AV/AP beginner series, (which I will continue after this brief interlude) I bring you a How to article on modifying the BLS 950 servo for external potentiometer. Now, almost all higher end servo shares common trait, so you can use this article for them with appropriate changes for design percuilarity.


WARNING: The SOME OF THE BOTTOM PLATE OF THE BLS950 SERVO IS GLUED TO THE PCB ON AND IF IT DOES NOT POP OFF EASILY DO NOT PLY IT OFF. YOU CAN DAMAGE THE SERVO IF YOU USE FORCE TO TAKE THE BOTTOM OFF.



now, if you want to turn this into 360 continous servo instead of external pot, you don't have to cut the potentiometer wire. you need to remove the mechanical limit pin and the plastic pot turner off the bottom of the main gear. center the potentiometer and reassemble. that is all you need to do....Continue Reading
Posted by askman | Aug 08, 2012 @ 12:31 AM | 9,732 Views
Setting REALISTIC BUDGET.

now, you understand that there is no free lunch and you have made good assessment of where you want to go with AP/AV. I kinda went over this in TANSTAFL , but we will go more into details in setting realistic budget.

First. assess what you have. Radios, Camera, etc. most people do have some of the items that you will need, and while it may not be ideal, it will get the job done. This is especially true for cameras.

CAMERAS:
rule number1: forget DSLR. I know people love their DSLR, but until you are ready to risk several thousand bucks everytime you fly, forget it. In fact, Best place to find a good camera is probably in your drawer.

Don't think you have to have latest greatest camera. Just because you saw someone posting great video or still from such and such cam, it does not mean you need the same to get good result. For example, I've been using Panasonic Lumix GF3 as my test camera. I got it off ebay and amazon (2 of them) for bit over 300 bucks each with 14mm pancake lens. this is about same price as gopro hero, but output is far superior. This does not mean gopro is a bad cam. in its case, it is nearly indestructible and produces very much usable video. I just needed something in Nex5 class without the tariff. Nex5 with 16mm would cost almost double that and with hacked firmware, the video quality is quite good off GF3. I would say superior in some cases to Nex5. for my use, I did not...Continue Reading
Posted by askman | Jul 17, 2012 @ 05:05 PM | 10,346 Views
as many of you know, I mostly hang around multicopter forum. Multicopter is latest platform and very popular one to hang camera on to. With technology advancement in gyro and automated flight, multicopter has become to platform to have. anyway, today is all about basics.

now, I've seen lot of post that goes like this.
hi, I am new to multicopter, I think it is great, never flew anything in my life, but I want a multicopter since I saw it on XX and I see the potential to make me rich and famous. my budget is $500.00 and I have several requirement.

1) I need controller with GPS and waypoint programming.
2) need FPV gear (i've done lot of computer flight sim, I know how to fly fpv)
3) I need it to be large enough to carry my D5 but gopro is fine for now.
4) I need fully stabilized gimbal
etc...

now, I know that many of us are excited to jump right in, but before we start any endeavor of this magnitude, you really need to consider what you are really after and assess your situation. In general, you really need to assess why you are interested in AP/AV.

For many of us, it is just cool to take video and picture from the Air. Most of us really are not out to make a living taking pictures though, beyond doing an occasional job for friends and family. (usually for little or no compensation) There are professional AP/AVers though. Most of them started as either accomplished Photo/videographer with some rc...Continue Reading
Posted by askman | Jul 03, 2012 @ 04:32 PM | 10,523 Views
well, I get a lot of queries about various things related to AP/AV as well as multicopter, so I decided to distill it down to this entry. In realtiy, the answer is TANSTAFL. So, that is the theme of this blog. If you are a reader of Robert Heinlein, you will recognize this term from the novel "moon is harsh mistress" It means "there aint no such thing as free lunch" and this really fits my answer. With new technology and competition, the price of things are dropping, but this rule wills still remain true in every aspect.


Reliability:


I will include redundancy into the reliability as well. In general, simpler the system, more reliable it is. but also, component selection can also make a difference.

Design consideration: design like Y6, Octo and x8 also has some redundancy in case of motor/esc/prop failure . So for best reliability, you want tri/quad, but you are trading off possible redundancy of other design. More motor means more weight and more things that can go wrong. Coaxial design also loses some efficiency. So in many ways, you are trading flight time and cost for reliability.

component selection: selecting a good quality motor that is large enough to handle the load is very important. don't try to save money on motors. it is not worth it. ESC wise, I prefer 30amp as minimum with N-fet design. luckily, you can get simonK flashed n-fet esc for good price, but serious guys will...Continue Reading
Posted by askman | Jun 29, 2012 @ 08:26 PM | 10,479 Views
if you've been following the thread on AG gimbals, you probably know that i am a proponent of Y and to lesser extent Quad for multicopter for AP. While I realize this put me in the minority, I find that for best flight performance in windy condition, Ys are hard to beat. to gain that benefit, you do lose bit of efficiency, but I think most of us are willing to make that trade.

Gary has been asking about the Y conversion kit for a while. he has shrimp and crab kit that he has to put together, but just never had the time, so he just wanted to convert the F550. when Bobolavega showed up with his conversion of both 450 and 550, I had to build one. I just created a simple motor mount conversion and that is all it took (you also need to take it apart and rewire it, but that is pretty easy on F550)

anyway, here is the pic and first good video from the gimbal that is on it.

Y550 test5 (3 min 32 sec)


I am still working on fine tuning it, but pretty happy with current result. To be honest, Shrimp is still better in stability due to compactness of the system and simonK flashed esc, but I am pretty happy with the result so far. but that also makes this an ideal platform to work out the improvements on.




Now, I get lot of question about gimbal controller. Currently, I test using controller built into naza, and HF gimbal controller. so, lets go over the list of available gimbal control solution.


1) DJI WMK : GPS lock...Continue Reading
Posted by askman | Jun 24, 2012 @ 09:53 PM | 11,872 Views
well, back to more prop talk. :

on my last update on april 30s, I've posted about gemfan cf mix prop failure. it happened again in AP use. so, I will put notice that it is not recommended to be used. The gemfans have also released some CF copy of graupners. biggest issue from what I've been reported has been QC issues. for how much they cost, they seem to have issues with hub being not consistent.


so, which are the best props for F450/550? or AP in general? well, Graupners are still favored by many, but I am having great result from using zinger wooden props.

Zingers have lot of pusher prop available, and 8x5 and 9x5 combo has proven to work as well or possibly even better than graupners in windy situation. graupners are still bit more efficient though. They do need to be balanced and bored for dji motors as they are 6mm standard bore. but they fly great.

now, some of the later batch of DJI motor (2212) seem to have vibration issues as well. on one F550 kit., I had 3 motors being unusable for AP. Earlier kits were fine, but not these. I've heard that DJI has since changed the motor once again. (etched instead of sticker logo with issue that graupners will not easily work without spacer now) dynamic balancing can help a motor, but I am finding that we cannot do it accurate enough for AP use. in another word, if you have to dynamically balance a motor, just replace it if you are going to use it in AP/AV. you can make it great for stick banging with dynamic balancing, but not for AP. this lead to another view in that you should always buy decent quality motors.
Posted by askman | Apr 18, 2012 @ 09:40 PM | 11,267 Views
well, I got my gemfans. they are nice blade. very well suited for DJI 450 and 550. you do need to drill out the hub. hub diameter is similiar to DJI blade, but with carbon reinforcement, the blades are much stiffer and should be stronger. I used step drill to get it close and reamed the bore hole to .3135. tight fit on the motor. they needed very little balancing, and it was ready to put on.

One thing I noticed about puttng on the new blade were that my 450 and 550 both were bouncing around more in the wind. they were no longer solid anymore.
so, I did a quick and dirty experiment to determine the cause, most obvious being the diskloading.

my 450 were at 1.5kg, and 550 were at 2.6kg. both with 8" and flew well in wind. this is about 200sq in and 300 sq in disk area. 1.39sqft and 2.08sqft leading to 38oz/sqft and 44oz/sqft. both flying very well.


with 9" blade, same weight, my disk area is now 254sqin and 382sqin. 1,76sqft and 2.65sqft which lead to disk load of 30oz/sqft, and 34oz/sqft.

while hexa was more stable, it still was not as stable as the quad with 8".

so, to prove this test out, I added weight to quad and brought it upto 1.85kg, which brought the diskload to 37oz/sqft and now it was almost as stable as before. . I've brought the f550 to 2.9kg and also repeated the test. and it was same . (about 40oz /sqft) very stable.

so, at least in windy condition, naza really...Continue Reading