Brians Hexacopter Build..

[Brian]

Hi all, I have an RCTimer RCT800 hex frame and I';m going to be using these motors...

http://rctimer.com/index.php?gOo=goods_details.dwt&goodsid=811&productname=

and 15" props. Is this going to be a good combination? If so what batteries will be good for them? I am sort of looking at running a pair of these at the moment...

http://www.hobbyking.com/hobbyking/store/__32264__Turnigy_nano_tech_5000mah_5S_35_70C_Lipo_Pack_UK_Warehouse_.html

I have these 40A ESC';s in the post at the moment...

http://rctimer.com/index.php?gOo=goods_details.dwt&goodsid=850&productname=

Here';s a pic of the build so far...

Yup, not a lot has happened as the rest hasn';t arrived apart from a pair of liPo alarms.

Its going to be using a Naza/GPS, and running a 2 axis gimbal with a Gopro. I am also going to be running an FPV set-up.

Thanks for your help guys,
Brian

[Balders]

Those are the same esc';s as I';ve bought for my hexa project, so yeah I think they should be good.

If you are thinking of 15" props, I think 5S may be a bit too much, if you';ve got some 4S batteries, they may be plenty.  Obviously your motors are pretty low KV, but I tested my 690kv';s on 4S and got night on 2kg';s thrust on one motor on a 12" prop.  Hope that helps.

[Brian]

Ok, 4S it is, cost will be better too! Now have to wait for HK';s site to change pages for 5 minutes!!

Brian

[Smeagol]

Ok, 4S it is, cost will be better too! Now have to wait for HK';s site to change pages for 5 minutes!!

Brian

I find that google chrome works better with HK site

[Brian]

Would this be worth a try?

http://www.hobbyking.com/hobbyking/store/__32215__ZIPPY_Flightmax_8000mAh_4S1P_30C_UK_Warehouse_.html

Brian

[homersainty]

Christ that battery weighs nearly a KG 

[Brian]

One other thing, I';m looking for affordable landing gear. Must be large enough not to tip the thing over on landing, and not too exspensive. Any ideas?

Brian

[Brian]

Build update...


I have soldered my ESC';s and a battery lead onto the board...


Just waiting for pay day, and then I';ll order motors, bigger props, batteries, bits and bobs etc...

Brian

[teslahed]

Looks very nice - glad to see I';m not the only one who gets mildly OCD about the symmetry of these things

[Brian]

All, my stuff is ordered now - just waiting for HK, RCTimer, and Ebay sellers to get their act together and deliver it all!!!

Cant wait,
Brian

[johnrs]

Did you manage to source a landing gear as this is something I want to get hold of..

Newbie question... ..Could someone explain the relation between ESC, Batteries, motors and props

Was the comment below by Balders that I was not sure on...

If you are thinking of 15" props, I think 5S may be a bit too much, if you';ve got some 4S batteries, they may be plenty.  Obviously your motors are pretty low KV, but I tested my 690kv';s on 4S and got night on 2kg';s thrust on one motor on a 12" prop.  Hope that helps.

[Brian]

No landing gear yet, but I';m thinking of just bunging some sticks on the end of my arms. I have some 20mm plastic tubing, and I';ll just cut some 20cm lengths and bolt them to the ends of the arms.

Still not too sure about all that stuff, but I';ve just sort of copied what RCTimer have tested for the S800 frame.

Brian

[Balders]

Did you manage to source a landing gear as this is something I want to get hold of..

Newbie question... ..Could someone explain the relation between ESC, Batteries, motors and props

Was the comment below by Balders that I was not sure on...

I';ll try to explain...

The higher the cell count, the higher the voltage, and correspondingly the higher the motor rpm if flying in a manual mode.  So if you think about it, one extra "S" in the cell count (5S vs 4S) gives an extra 4.2 volts, so given that KV is rpm';s per volt, say the motors are 700kv, that';s an EXTRA 2940 rpm for the same given throttle opening, which on 15" props (generating a pretty huge amount of thrust) would make it almost too powerful.

Note that none of this applies if flying in Naza';s gps mode as the electronics/gps/baro will compensate, but if it';s hovering at half throttle and Brian switched to manual mode, it';d take off like a rocket!

[Brian]

Update...



I bin done some building!

Brian

[Brian]

And a bit more...


Added the VMU for the Naza, and my tupperware lid thingy...

Brian

[benchmark]

Goodness me, that is BIG!!! cant wait to see it fly.

[Brian]

New gimbal arrives...

Step one, take stuff out of bags,


Step two, build...


Easy!
Brian

[Thomas]

Hi Brian.
It';s looking a bit tasty  ;D. How much do you estimate the total build is  costing (including shipping etc). Any chance of posting a spec list?

[Thomas]

Apologies. I didn';t see the first post

[Brian]

Lots!

Brian

[shaktar]

looking nice

Is that the RC timer one? I just bought one and the same frame as you for a big project

[Brian]

Yes it is mate. My landing gear arrived today, but only one battery tray where I';d ordered two. I only have half the screws needed for the landing gear and the screws supplied with the battery tray don';t fit the fittings. Not a happy bunny at the moment, have emailed RCTimer about this, and I';ll keep you posted about it...

Brian 

[QuadBod]

New gimbal arrives...

Hi Brian,

I have the same gimbal, and finally got around to putting it together at the weekend. Dead easy as you say, but a couple of things you may want to look at:

There should have been some nylock nuts in the bag, and you may want to use those to hold the push-rod posts in place so that they can rotate. If you use the nuts that came screwed on the posts, and loosen them enough that the posts can turn, they';ll probably fall off in flight (unless you used thread-lock). If you don';t loosen them, the servo rods have to bend.

Next, whilst it isn';t shown in the assembly instructions, or in the product photo, there';s a second mounting hole on the opposite side that lets you make the roll servo push-pull, like this:



(There should have been a third rod and post in the bag-o-bits.)

It';s slightly disappointing that rctimer didn';t include ball-link push-rods, or use bearings. Even the cheapy $3.99 HK pan-tilt mount has bearings and ball-link joints! It would have cost rctimer pennies to include them in this gimbal, and made quite a difference to the finished product.

It looks like the washers for the bushes holding the camera mount have too large an internal diameter for the screws used. They still do the job, but it';s a bit sloppy.

Also, no anti-vibration grommets. The bumblebee camera mount has anti-vibration grommets both between the gimbal and the hanger, and also a second plate that the camera attaches to that that isolates it from the gimbal with another set of grommets, and it';s 2/3 of the price. (Albeit only single axis, which is why I went for the rctimer one, but it suggests they put a bit more thought into the design (or copied a design that had more thought put into it <g>).



The links are easily replaced, so that';s first order of business. Bearings might be a bit trickier. I haven';t figured out exactly how I';m going to attach it to the quad yet, but my temporary propeller-elastic solution is surprisingly sturdy, and remarkably vibration free (no jelly on the GoPro).  Any idea what the battery-strap-like slots on the gimbal mounting plate were designed for?

The joint between the camera mounting plate and side-arms is a bit of a weak point. It was a tight fit slotting them in, but there';s a lot of lateral movement that could translate to vibration. Other gimbals use a block screwed into the joint, which is what I';ll probably do, although I quite like the approach used on this one, with ali rods holding the base together:



Sadly there isn';t any way to do that with the CM102 without replaceing parts (and I don';t have a laser cutter!  )

If this one was CF it would tick nearly all the boxes for a cheap gimbal:



Pity it';s glass-fibre, and the base plate arrangement is a bit iffy, even though it has the extra damping - not much room between the front and back supports for a bigger camera.

Finally, ("yes, finally!" you say  ) this looks like it might make a good upgrade:



Belt drive supposedly being smoother and with less backlash. OTOH, how far do you go with a $60 gimbal?  :huh 

[Brian]

I do have the extra rod and post which I';ll fit tomorrow. And I';ll get those nylock nuts on there tomorrow. They also supplied better self tapping screws for the servos. The ones that came with the servos just kept slipping. So I think any feedback that they have been given must have been taken seriously. That is a good sign.

Its the pitch axis that I';m most interested in, on my last (cheapo) gimbal it was juddering a lot, this is why I bunged a bit more money into this one. I know part of the reason for this was the cheap servo that I used, but also the weight of the Gopro and waterproof case it comes in (I will NOT take it out of the case!) The servo';s that came with this one are metal gear jobbies and seem a bit tougher.

The other thing I dont really like is the plate that you screw the camera onto is only slid onto the thingys (you know, the little hanging thingys... Its a technical term...) I';m going to notch the little hanging thingys with my Dremel so that the plate clips in firmly. Another job for the mythical "Tomorrow!"

Brian

[Brian]

Thanks for those tips mate, I have changed the nuts over and added the second rod etc. not done the Dremmeling yet as I don';t want my neighbors kicking my head in!

Brian

[QuadBod]

The other thing I dont really like is the plate that you screw the camera onto is only slid onto the thingys (you know, the little hanging thingys... Its a technical term...) I';m going to notch the little hanging thingys with my Dremel so that the plate clips in firmly.

That';s the bit I was saying that a block (maybe nylon) screwed into the corner between the side and base plates of the camera mount would add a bit more rigidity to to who assembly for not too much weight.

I tried to do the same as you';re suggesting (but with a needle file) and ended up making the whole thing loose.  doh!

How are you planning to attach the gopro to the gimbal, or the gimbal to your quad?

[Brian]

I have a tripod mount for the Gopro, so it just screws on with a bolt.



This does make the camera top heavy, but hopefully these servos will be able to cope with it. Even a nut and bolt would do the same as the little block thingy that you said, but there';s always the alternative, Hotglue and cable ties!
Brian

[QuadBod]

How';s this for an option to secure the camera plate to the side:



See how the bolts go through the basep-late and into a notch in the side plate which holds a nut... It won';t add much lateral rigidity, but it';ll certainly hold it together better than friction!

[neil-liverpool]

hi is your 800 finished now, if so, what do you think of it?

[Brian]

Not yet, I still have all the calibrating to do, as well as finding the best way to mount the props - and which ones do I use - To be honest I';m just plain worried about it all. Gaza can explain, I';m mucking about with RC cars at the moment till I get my confidence back. My quadcopter crashed to death on its last flight, and I don';t want that to happen to the 800mm monster!!

Brian