Quadcopter build log with HK multi-rotor board V3

[Pikle6]

thanks satyagupta for your advice regarding the hk frame i am feeling confident looking at the frame itself


Subbu

[satyagupta]

thanks satyagupta for your advice regarding the hk frame i am feeling confident looking at the frame itself

You are always welcome buddy

BTW whats the weight of the frame (just arms and mounting plates)??

[Pikle6]

hi guys the monsoon is finally doing some catching up this week, rains are much more frequent now. and the gloom has caught up with me too. feeling a lot lazy these days.

onto the update the frame is all done and motor mounts marked out for cutting and drilling tomorrow.

now onto the big question, i want to be realistic here the frame weight is about 600 -700 gms and the thrust at full throttle is about 0.632gms from each motor and i shall be using a 4000mAh 30c 11.1v turnigy lipo which is another monster, what do you guys think will it take off from the ground ?.

as i see it it should hover but not much altitude and flight time. i shall be going ahead with the present setup anyway since i am planning to use this frame as a platform for aerial photography. if needed (which i sincerely feel i will) i shall upgrade the power system.

i have used this motor with a 9x5 prop on my yak55 and it can make it go vertical. the yak with the new plywood frame restructuring weighs about 800 - 1000 gms with the battery so such performance makes me wonder about its performance on the quad if it shall succeed or not.

kindly let me know the pros and cons of this setup and how i could help manage its weight. also it being a 315W motor vibration may kill the stability of the quad too. i would like to have all experts on board onn this build.

the first pro which i shall add is the frame is super strong and very adaptable (and i really want to use this frame )

i shall weigh in all the suggestions and proceed ahead (And literally weigh in all the parts on a scale too). attached are a couple of pictures

Subbu

it shall be unfair if i did not mention it here my friend HarshVardhan helped me a lot (and i mean a lot) during this and my hovercraft build for which i shall be ever grateful  

[yogeshkannan]

awesome frame bro  
good luck with the build ;;
gonna upgrade my quad pvc frames to aluminium frames .

[satyagupta]

Yo bro good going, couple of things to help you out..

When you said:

frame weight is about 600 -700 gms and the thrust at full throttle is about 0.632gms

You mean 600-700 gms including electronics battery everything of just frame (arms and plates) no electronics mounted over it?? If it just frame then buddy you have to reduce a lot of weight (of the frame ) with my first build my frame weighted 600 grams just 4 x 1 feet aluminum arms and 2 x 5 mm plys and it was complete failure..

I had to rework on the frame for the complete reduction of weight. Couple of advices to reduce frame weight,

Drill holes in your arms, remove unwanted portion of your plates.. that might help a lot..

Now lets talk about the thrust, you get 0.632 Kg ( i am sure you meant 0.632 Kg not 0.632 gms ) so you get this at full throttle, so at full throttle your quad will get a total thrust of 600 gms x 4 that will be ~2.4 Kg which is not bad at all.

But here is what i have read a lot and got the same advice here on RCI too, your quad should lift of or hover at 1/3 rd throttle. i.e. if you throttle has complete 12 steps (as an example) after moving your throttle stick 4 steps your quad should lift of the ground.

Lets do some maths,
with 1/3rd throttle your motors will generate 1/3rd of the total thrust which is 600/3 = 200 gms
Now at 1/3rd throttle all motors will generate 200gm x 4 ie ~800 gms of thrust..

So the bottom line is your quad has to be less than 800 gms to make this work.. To begin with if you quad lifts off at 50% of throttle then that is also considered a good thing. But for hovering or aerial photography you need quad to lift off at 1/3 rd throttle. 

So we need to increase the thrust you can try with large prop 1047, even i started with 0905 props but faced problems with hovering my quad. But with 1047 props i get a very decent lift off at 1/3rd of the throttle. But then you have to buy new props, if you are not looking to buy new things until you get a decent flight (which i did) try to reduce weight of your quad.. Call me up if you have any issues

[Dharmik]

Bro i am wondering how it reached to 700 grams with just 4 arms, 2 plates and 8 nut-bolts. I agree with satya bro, you will have to reduce weight to half atleast. I did quick calculations
4x 60grams motors = 240grams say 250
4x 25grams esc = 100 grams
1 x battery = 350 grams
other misc things = 200 grams
Total = 900grams + 700grams = 1600grams(excluding AP stuff)
If you see famous ht fpv frame used by justine(juz70), it has 350grams weight
http://www.hoverthings.com/htfpvblack.html

[satyagupta]

Bro carfon fiber.. they are very light and sturdy...

I have replaced my 5 mm plys used for plates with carbon fiber.

Even 1 mm thick CF plates looks very sturdy.. Very very hard to cut.. and some care to be taken while cutting

[Pikle6]

hi dharmik and satya so i have some breaking news

the frame weighs exactly 475 gms

and the complete electronics weigh exactly 745 gms

i just went to a nearby grocery store and weighed them in i am attaching some pictures too kindly note there was a zero error on the weighing machine of 40gms so i had to reduce it from the total weight

now i believe i just have to reduce the weight of the frame by a little bit to bring it to about 350 - 300 gms max which i can achieve by reduce the length of the arms of the quad by a few inches on each arm.

spoke to satyagupta and got come ideas on how to reduce the weight few ideas are to reduce arm length and cut off the centre plate excess parts

i also need landing gear ideas(more weight   )


Subbu

pic 1 frame only weight

pic 2 electronics only weight (battery fc board motors esc and even some male to male cables)

[satyagupta]

I think your target should be to get the weight to around 800-900 gms which i guess can be reduced by reducing the extra length of arms, drilling holes on them.

[Pikle6]

hi guys i got the replacement esc from gusty bhaiya today now all the electronics are ready to go

thanks gusty bhaiya

Subbu

ps my mtnl connection has stopped opening any websites due to some dns resolving error so using the background reliance modem

[rcpilotacro]

You are welcome subbu, would like to see it fly

[Pikle6]

so after working on it for 2 days i managed to bring the weight down to 272 gms but the arms are a bit flimsy so reverting to 1cm thickness arms with smaller length and holes in frame to reduce the weight further

Subbu

[satyagupta]

Good stuff.. frame looks good..

[hyd_quads]

Motor - 4 X NTM Prop Drive 28-26 1000KV / 315W (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=21478)

I've been follwing the thread but it's the first time I'm seeing this. . I've been eyeing these motors for my next quad. I'm eagerly waiting to replace my rather crappy dt700s ( hardly 130W) with the 315W NTM2826s. Please post the videos and any motor performance data after you finish. Thanks,

Vineet

[satyagupta]

crappy dt700s

Why bro?? why crappy?? have heard a lot of good reviews about it and highly recommended for quads... please share your experience dude it would help a lot (like me) who are planning to use DT700 or DT750 for their quad..

[hyd_quads]

Why bro?? why crappy??

It's absolutely my personal opinion. I had bought them because they were being hailed as the verymotors for quads.
Although thier performance is fine, I feel their build quality is not. As far as build (and build quality) is concerned, I think multirotor motors should have a short shaft and long wires. Longer the shaft, more the vibrations. Althogh the shaft can be cut, I need dremel for that. Perhaps, nowadays, these features are becoming characteristic features of multirotor motors. And the mount too. The holes are located in a triangular arrangement, and most of us prefer two-hole mounting for quads. (atleast I do) So the holes cannot be perfectly linear while mounting. Considerign this, I feel x-mounts are better.
Consider all these, I think parkflyer-type motors are better, like the NTM2826 1000kv. (pikle6 aka Subbu uses them on his quad). I'm waiting for more reviews on that motor.

But it seems I'm the only not satisfied with dt700/750s. There should be a reason why everyone likes them. I'm still searching for that.
Also, I think my frame is also crappy (at 400+ grams), so I'm rebuilding it with lighter fiberglass and 2channel aluminium.
Vineet

[anwar]

ps my mtnl connection has stopped opening any websites due to some dns resolving error so using the background reliance modem

Offtopic, but this may be useful.  I realized that my home DSL connection from BSNL was acting up.  A little looking around proved that the connection was there and it was fast, only the DNS servers used by BSNL were overloaded.  Browsing anything by IP was instantaneous.  So I reconfigured my DSL modem/router to use OpenDNS's DNS servers, but they were also acting up from time to time (not sure if this was BSNL interfering, or if OpenDNS itself had issues).  A little more reading proved that our friendly neighborhood "Do No Evil" company (Google) was providing DNS service, and their servers were very fast.  So if you are having DNS issues, please try these 8.8.8.8 and 8.8.4.4.  That is, if you are willing to trust Google... the big brother

[Pikle6]

finally finished the frame going with the 10mm thickness ply arms will go ahead and reduce the weight from the frame after i put on the electronics now.

some pics i know the frame is a bit overweight but i will find some way to reduce its weight further since i cannot reuce the thickness of the arms anymore or else the become very flimsy


Subbu

[Pikle6]

so the motors are mounted, escs connected, fc board battery and rx all ready to roll but then i remember of the battery harness for the esc's and battery just working on it right now should be done in an hour.

sea trials begin (hopefully) tomorrow  

Subbu

[satyagupta]

great let us know the the test flight results... all the best

[raja_mastana]

All the best Subbu, great effort!! 

[Dharmik]

Pikle bro have you tried KK2.0? I heard auto-level is bit tricky to tune in this version.

[Pikle6]

hey dharmik yes you can either change the p and i gain values in the self leveling menu or you just keep calibrating the sensors (its automatic) until you get a true zero point

that however is out of the question since my arms vibrate like hell when i power them on i desperately need better mounting ideas for mounting a motor with a downwards protruding shaft onto a plywood arm please help


Subbu

[Dharmik]

I think your frame is fine but this board is very sensitive to vibrations.

[Pikle6]

dharmik i never even mounted the kk2 board yet so no problem with the sensitivity there

the static full throttle rpm without props generates a lot of vibrations all transmitted to the central plate with refrain me from mounting the board without solving the motor vibrations issue please suggest some way i could get rid of them should i use aluminium arms or any other suggestion would be helpful

Subbu