Help With Heavy Lift Hexacopter

[aricolton]

One thing I just thought of: Will I have any trouble maneuvering an X8 octo with 17" props through a gate that is 2 meters wide by 1.5 meters tall?

Thanks again for all the help!

 

[jes1111]

One thing I just thought of: Will I have any trouble maneuvering an X8 octo with 17" props through a gate that is 2 meters wide by 1.5 meters tall?

Probably gonna be quite tricky - but if it wasn't then the competition wouldn't be much of a challenge, would it?

How high off the ground is the 2x1.5mm gate?

 

[aricolton]

How high off the ground is the 2x1.5mm gate?

The height of the gates will vary anywhere from 2 meters above the ground to nearly touching the ground.

With just a basic KK2.1 flight controller, how tricky will it be?

If one of the props were to brush up against the side of the gate, would the copter go out of control?

I should also add: the competition is indoors, so wind won't be an issue.

 

[jes1111]

How long have you got to build this puppy and practise? Nothing's going to be easy if you want to win. Touching a prop may or may not end in disaster - depends how lucky you are that day

http://youtu.be/8F0Q0v7H_9Q
http://youtu.be/wDHXVROPGEk

 

[aricolton]

We have just under 2 months, Building shouldn't take more than a few weeks, so we should have about a month to practice.

Ya I have seen those videos, they lift all that weight with 16x10 props, so maybe 17 is overkill?

 

[jes1111]

they lift all that weight with 16x10 props, so maybe 17 is overkill?

Ask eCalc - my guess is that 16x10 props are going to drink the juice - a pitch ratio of 50% is about the max you want for hovering - i.e. 16x8, 17x8.5, 18x9, etc.

btw - You might have trouble getting a delivery from HobbyKing in under 2 months!

 

[aricolton]

OK, I might just stick with the 17x8 props.

HobbyKing takes more than 2 months to deliver orders??

On their website it looked like we could get it delivered in something like 10-12 days...

Is there anywhere else you can recommend buying the components? We are located in Texas.

 

[jes1111]

Be careful to only order goods from the "USA Warehouse" - if you order from the "International Warehouse" (i.e. China) it can take forever. I'm in UK so can't help you with USA alternatives.

 

[aricolton]

Ok, thanks for the heads up.

I looked into it and it ends up we really can't go over budget at all, so the 17" props with the big motors isn't going to happen.

Have have downsized to this, it is about all we can spend. It is not nearly as powerful, but how does it look? Do you see anywhere we can get more power without spending any more money?

View attachment 16296
It uses this motor: http://www.hobbyking.com/hobbyking/store/__19831__NTM_Prop_Drive_Series_42_38_750kv_785w.html

Thanks so much for all your feedback!

 

[jes1111]

Staying with a big prop (which is what you need to lift weight) , I found a nice motor to suit, and it's only a little more than that last motor you proposed:

http://www.hobbyking.com/hobbyking/..._Brushless_Outrunner_600kv_US_Warehouse_.html
http://www.apcprop.com/ProductDetails.asp?ProductCode=LP18055MRP
http://www.apcprop.com/ProductDetails.asp?ProductCode=LP18055MR


View attachment 16297

Still on 4S and 60A ESCs - according to eCalc you could tip 20kg AUW :tennis:

EDIT: remember to set your battery charge state to "full" in eCalc

 

[jes1111]

http://www.hobbyking.com/hobbyking/...ng_Red_Brick_60A_ESC_Opto_USA_Warehouse_.html

Basic, but should do the job

 

[JoeBob]

That first YouTube video lifting 50 LBs with a 685 mm span octo looks very similar to your required bird. Motor hub to motor hub was 27 inches. Is that how y'all are being measured?
From the video:
Turnigy G60 (500 KV)
100 amp ESC (Simple Series)
16x10 APC props (?)
KK Controller V2.1


I would stay away from wood for your frame. You are putting some serious stress on the center section.
And you want the frame arms to be as narrow as possible. Wide wooden arms will block your airflow and reduce lift. (Think of a window fan trying to blow around a 2x8.)
Source for Aluminum square tubing:
http://www.onlinemetals.com/merchant.cfm?pid=20737&step=4&showunits=inches&id=1270&top_cat=60
.285 pounds per foot
24 inch piece for $3.18.

You know that you're gong to have to post a video for us when this beast flys, right?

 

[aricolton]

I would stay away from wood for your frame. You are putting some serious stress on the center section.
And you want the frame arms to be as narrow as possible. Wide wooden arms will block your airflow and reduce lift. (Think of a window fan trying to blow around a 2x8.)
Source for Aluminum square tubing:
http://www.onlinemetals.com/merchant.cfm?pid=20737&step=4&showunits=inches&id=1270&top_cat=60
.285 pounds per foot
24 inch piece for $3.18.

You know that you're gong to have to post a video for us when this beast flys, right?

Ok, the only reason we chose wood initially was becuase it would be easy to work with, but that aluminium tubing does not look like it would cause much trouble, and it is surley a better material for this sort of thing, I will definitely consider using that instead of wood

Staying with a big prop (which is what you need to lift weight) , I found a nice motor to suit, and it's only a little more than that last motor you proposed:

http://www.hobbyking.com/hobbyking/..._Brushless_Outrunner_600kv_US_Warehouse_.html
http://www.apcprop.com/ProductDetails.asp?ProductCode=LP18055MRP
http://www.apcprop.com/ProductDetails.asp?ProductCode=LP18055MR


View attachment 20266

Still on 4S and 60A ESCs - according to eCalc you could tip 20kg AUW :tennis:

EDIT: remember to set your battery charge state to "full" in eCalc

Ya those motors seem like they would work well. I might just stay with the 17" props so we don't have to worry about having to overlap them, we can still get about 18Kg AUW.

You know that you're gong to have to post a video for us when this beast flys, right?

When we get it in the air I'll be sure to video tape it for you guys!

 

[JoeBob]

Aluminum: the 6061 is more rigid.
And it comes in many sizes :
http://www.onlinemetals.com/merchant.cfm?id=1270&step=2&top_cat=60
The 1" x .0625" that I linked you to might be too thin. Decide how you're gonna attach motors above and below, and pick a size.

If it were me building the frame, I'd use Epoxy and four small pieces of angle:
http://www.onlinemetals.com/merchant.cfm?id=62&step=2&top_cat=60
Pop-rivet them together and be done:
View attachment 16298

If you go with the 18.5 props that jes1111 is recommending, I'd use 1.25 inch square tubing to be sure that the overlapping tips don't touch.
(jess1111 has been doing this much longer than I have. I'd take his advice.)

jess, any idea how tall the profile of those APC props is going to be? Will 1.25 inches of vertical separation be enough?

 

[JoeBob]

If you use 1" x 2" Channel http://www.onlinemetals.com/merchant.cfm?pid=20270&step=4&showunits=inches&id=1008&top_cat=60

on the upper attachment, you'll have battery trays:
View attachment 16305

As long as I was in Google Sketchup, I drew it out exactly with 18 inch props.

View attachment 16306

The motors that Jess suggested are 2 inches high with a 2 inch diameter.

View attachment 16307

You'll have some nice overlap. See any wasted airspace?
View attachment 16310 View attachment 16308

And the props should clear easily:
View attachment 16309

You add the bottom props. Ack! I'm telling myself to butt out now!
You better make an 'A'...

 

[JoeBob]

Compulsive? Me?

You can offset the motors when you mount them on the ends of the arms to provide easier access to the screws and catch a little more air:


View attachment 16312 View attachment 16311

Now I can sleep.

 

[aricolton]

That looks great! I will take those ideas into consideration when we build the final frame.

I will be ordering the parts in the next few days, I will let you guys know how it goes.

Thank you so much for all your help!