Inspired by Inspire, DJI A2/H3-3D XY4 Quad Build with a twist

[Bartman]

Was surfing the internet blindly just now and thought to check if the Futaba S-Bus converter was back in stock anywhere (I wasn't expecting it to be, thought it was a fantasy item that would never arrive, fwiw) and it was!

http://www.espritmodel.com/futaba-s-bus-sbe-1-pwm-adapter-encoder.aspx

So I ordered one, so I'm going to have one more go making the A2 work via an S-Bus adapter, so I'm going to try to do the 2-axis-as-3-axis trick with an A2 one more time, so I'm going to sell the A2 cheap if this doesn't work, so I'm still not happy that DJI is requiring paid customers to pay an additional $180 to make a feature work that is already bought and paid for, so I'm also going to go back to proper sentence writing but after surfing the internet blindly for the last fifteen minutes i'm in an unedumacated zombie like state, so that is all for now.......awaiting shipment (again)

 

[Motopreserve]

Nice. Looking forward to seeing you pull this off...obviously after some rest from the Internet surfing (I think you'll need your wits about you for this one!)

 

[Bartman]

well this is exciting! the Futaba S-Bus encoder just arrived and I hurriedly hooked it up to see if the A2 would register a signal and it did! The next step is to wire it all up with the Pololu switch and the second receiver to see if the S-Bus encoder minds a micro-second gap as the module switches from one receiver to another. If the S-Bus encoder takes that in stride then I think the project will move along to completion rather quickly and I'll have an A2 guided quad with nearly the capability of the Inspire 1 and maybe 30 minute duration.

Excited again.
Bart

 

[Bartman]

32 degrees tomorrow so no reason why I shouldn't be able to do a first flight if everything falls into place tonight. i might scratch one project off of my to-do list tonight! woo hoo!

 

[Motopreserve]

32 degrees? It's like Hawaii down there!!!

Good luck with the test.

 

[Bartman]

well, good news and bad news

the good news is it all worked perfectly....switching to IOC (Carefree Mode) caused camera tilt and heli yaw to transfer over to the second receiver turning the one man helicopter into a two man operation. that is one big sigh of relief out of the way!

the bad news is, I'm about $180 and a three week wait away from everything working correctly because to use IOC with any confidence I've got to replace the GPS puck with DJI's newly updated one.

but I'll put the A2 back into the helicopter tonight and will do the calibrations and try to fly it tomorrow sometime. if all goes well I'll consider buying the new GPS puck but I won't be happy about it.

 

[Bartman]

After what has been a crazy build, this one is finally done! It flew briefly today, the loose bits are all tidied up, and it's parked in the corner of the basement awaiting better weather.

The big surprise here is that the Futaba S-Bus converter, which saved this build and allowed it to be completed as originally intended, is very light, small, and works exactly as advertised with no set-up required...just plug it in between your receiver and flight controller and it gets right to work converting your discreet receiver outputs into a single S-Bus feed. An LED in the case indicates if it's happy and working properly.

And thank you again to GotHeliRC.com for sponsoring the camera mount in this build. As soon as the weather begins to ease and I can get an assistant to go fly with me we'll do a report on the DJI H3-3D camera mount.

Final weight with everything attached, secured, present and accounted for is 4.00 kg even which is .05kg over the target of 3.95 which isn't bad! That includes the video transmitter and antenna, the S-Bus converter which wasn't in the original weight estimate, some extra wires, tons of zip ties plus everything else.

Sorry if the photos are a touch blurry, I'm blotto from going and going all day and didn't feel like cleaning the shop and getting the tripod out! Here's the final weigh-in to make it official;
View attachment 23521

A close up of the switching module from Pololu.com that lets the helicopter go from single operator to dual operator at the flip of a switch. It's got a silicon pad under it to keep the exposed electronics from shorting out on the carbon fiber frame plate.
View attachment 23516

And a few more build photos...
View attachment 23519 View attachment 23515

You can see the Futaba SBE-1 S-Bus converter sitting on top of the JR 921 X receiver, it works perfectly!
View attachment 23514 View attachment 23513 View attachment 23511

Second receiver for camera pan/tilt awaiting activation via the first receiver and the Pololu switching module
View attachment 23518

 

[Motopreserve]

That turned out to be a great solution to the problem.

Well done!

 

[Bartman]

Thanks! I got lucky to have it work so well for $60! what's nice is just knowing it's available for other builds and that it works well because you can basically now use any receiver with any flight control even if the system prefers an S-Bus input.

I'm not blind to the fact that this is a DJI A2 that we're talking about here and I only flew it today for a few minutes so there's a lot of trust remaining to be built up between myself and the new heli but I'm encouraged by the utility of the S-Bus converter. Not too expensive and works as advertised!

 

[Kratos]

This is what am I looking for But A2 is over my budget! So how much this cost you (without A2) and is it possible to have same controlls and Carefree Mode with Naza v2? I will copy this project if you dont have problem with it ( I will use different blades and motor and color xD)

 

[Bartman]

This is what am I looking for But A2 is over my budget! So how much this cost you (without A2) and is it possible to have same controlls and Carefree Mode with Naza v2? I will copy this project if you dont have problem with it ( I will use different blades and motor and color xD)

This can be done with a NAZA-M V2, I had built one like that but then traded it away this past winter. I missed it but decided to redo it with the A2 and 6S power. With the NAZA you won't need the s-bus converter but everything else will be the same.

Bart

 

[Kratos]

And can you write specs, I cant find this frame, I found similar tarot but I am not sure about size?

 

[Bartman]

the frame is my own design so i can't tell you where they're available as i shut the shop before it had a chance to do very much! if you really want the XY8 planform then a hex could be easily converted by leaving out two arms. the MT4008-18 motors need 14 to 15" props although three blade 12 or 13" props may do well also depending on the frame set you're starting with.

 

[Kratos]

I was looking Tarot but I am not sure because distance from motor to motor, if it is too small than I can't use big props like 14 or 15, can you remember distance from motor to motor? Also minimal gap between two close props is?

I just calculated, if I use 14' props with gap of 1 cm between and angle of 120 degree of frame from motor to motor need to be 74 cm. This one is little shorter but I think it will do the job

 

[Motopreserve]

Kratos, this concept is not dependent on the frame/motors/props at all, so you'll be best served by designing the MR that best fits your needs, using a Naza as the FC, and then following @Bartman procedure here.

 

[Kratos]

Yep I know it is inspire by inspire... anyway it fits my needs, half hour of flight and go pro 3 way axis... I am in technical problems now how to prepare everything Do you know what is minimal gap between two props?

 

[Motopreserve]

Start a new thread, people will find your questions about specific design choices better.

About 1" between props is safest. But I have seen closer to 1/2" too.

 

[Bartman]

1/2" is plenty, i'm not going to have time today to research frames but anything that allows up to 15" props will work fine. if you want an XY-8 just get a hexacopter and leave two arms out.

 

[Motopreserve]

Quadframe makes strong frames that can be ordered with various length booms to fit a build. The motor mounts aren't as trick as Bartman's though

They have a European distribution too, depending on your location.

 

[Bartman]

If I thought there was interest I'd do a run of ten or twenty frames! I certainly have enough motor mounts, boom clamps, and landing gear!