Dual Mode (Hopefully) Tarot Ironman 650 Build

[SJBrit]

I've been flying a Phantom 2 for a while now and realized a few months back that a generic platform like that is great to learn with but has its limitations. So. I've spent all summer reading and trying to get smart enough for this build - my first.

A little about my flying: This is an AP platform for a GoPro, and my main subject is foxhunting. It's a beautiful sport that I've been photographing for a while (http://adrianjennings.zenfolio.com/portfolio) and my few snippets of aerial video at the end of last season caused quite the stir in the community: http://vimeo.com/89873549.

So, the goal here is to build a platform to do a lot better than the Phantom which has two main limitations for me: noise, and short flight time. The noise is obvious: although none of the horses or hounds seem to take the slightest bit of notice, obviously I want to be as discreet as I can. In terms of flight time, I often need to hover over a covert as the hounds are cast for 10 minutes or so and I need to have plenty of juice left to stay on the hounds when they are gone away. The last thing I need is range of operation, and the ability to get my radio signals (up and down) through trees.

My hand-wringing came in terms of balancing duration with the ability to operate in potentially strong winds. That's what held me up for a long time until I had a brainwave that I really hope pans out!!

So here's the plan:

Frame: Tarot 650 Ironman. I thought long and hard about the planform and in the end settled on a quad. I wanted to invest in a high end drive system and I realized that going to a hex or a quad would quickly stress my budget and have me buying lower quality components. Also, it's just a GoPro! I didn't want to drop $1k+ in drive components to lift a $300 camera!

Motors: KDE 4014XF 380kV. Like I said, I wanted to go big on drive quality and I loved what I've been reading about KDE (especially Patrick's dedication to providing great support). I decided on these motors since they could work at the voltages and prop sizes I selected.

ESCs: KDEXF UAS35. Again, I just like what I hear about KDE. Also, I'm a beginner so buying ESCs matched to the motors was a big deal for me.

AP: DJI Naza M V2. I've had a great experience with my Phantom so I have no reason to change this.

Gimbal: DJI H3-3D. Same deal - I love this gimbal and have had a great experience with is so far.

Radio: Immersion RC EzUHF. I've been running this on my Phantom for a while and I love it - should give me the range and foliage penetration I'm looking for.

FPV: 900MHz Hobby Wireless downlink and DJI iOSD Mini. 900MHz for range and foliage penetration (yes, working on that HAM license now).

Telemetry: Immersion RC Tiny Telemetry. This gives me real-time GPS location streamed to my iPad and battery voltage and current consumption.

On the ground: Futaba 14SG (already using that with the Phantom and you'd have to pry it from my cold dead hands if you wanted to take it from me!!). Plus the usual stuff: screen, DVR etc. The DVR gives me playback of the Tiny Telemetry data should the worst happen and I have to go find my quad....


OK, so here's the dual mode part. I realized that for endurance I need larger, slower spinning props, but in the wind I'll need the added maneuverability of smaller props at higher RPMs. So, I decided to use two different battery/prop combos to get the best of both worlds on the same basic platform:

Endurance Configuration:

Batteries: 2x Multistar 4S 10A

Props: T-Motor 17x5.8 Carbon.

In eCalc that gives me 32+ mins at 54% hover and about 5000 RPM. Here's the stats:

Performance Configuration:

Batteries: 2x Multistar 6S 5.2A

Props: T-Motor 14x4.8 Carbon

eCalc says 22+ mins at 44% hover and 7500 RPM:

If that doesn't quite do it I can go to 8S and 12" props. The big challenge now is going to be finding AP gains that will work for both setups, or a simple way to switch gains - not sure about that yet.

First pic:

I'm a bit stalled now waiting on some parts: I've ordered another center plate to make another layer. The ESCs are going on top here with another plate over them to carry all the electronics and battery up top. It took some messing to get the KDEs to work with the stock 650 mounts but I got it sorted and it's a solid and tidy fit now. I'll post some more pictures when I get it built up some more.

I'm pretty excited! This build has been a long time in the ponder-stage so it's good to be strapping it together I have quite a bit invested in this so I freaking hope it flies well!

 

[SJBrit]

That's the power layer done. ESCs installed (not hooked up yet), BEC for the FPV Tx, current sensor for the Tiny Telemetry and pigtails for battery-in, PMU, gimbal GCU and voltage alarm. I have another center plate coming which will layer over this and then I can mount all the electronics up top. Starting to take shape!

 

[Pumpkinguy]

I'm just a newbee p2 owner but love what you've started here. I'm posting so I can keep track of your build. Cheers.

 

[SJBrit]

I had to make a rear battery holder from a spare top holder since the rear holder for the 650 is VERY puny - I'll be hanging some big batteries from here so it needs to be secure. This is an extra top battery holder plus four of the anti-vibration mounts and a little drilling:

The position of the rear battery is adjustable along the rails so I can balance the GoPro. That means that when I run a single battery I will use the rear one to maintain balance. When I add a second it will be on top of the center plate right on the C of G which means I am balanced with either one or two batteries depending on what I am doing. Here's the balanced position of the GoPro with the rear battery where I have it right now - I'll figure out exactly where I need it to be to clear the props from the image once everything is a bit more together. The longer CF tubes are from my local hobby shop - I"ll chop them to a reasonable length once I have the camera location finalized.

 

[SJBrit]

I finally got the extra center plate yesterday so I've been able to finish the build. Here it is almost ready to fly - just got to wire the battery connectors on and hook up the gimbal and Video Tx. I'm really happy with how it went together with the ESCs and power distribution on one layer, then adding another layer on top for all the rest of the electronics. I have no idea how I'd have stuffed everything in there if I hadn't doing it this way - ESCs hanging underneath I suppose. Anyway, a little more soldering in the morning then the moment of truth....

 

[Pumpkinguy]

Awesome. Are you as excited as me to see how it performs?

 

[SJBrit]

Awesome. Are you as excited as me to see how it performs?

A little nervous... ;-)

 

[SJBrit]

It flies!! No hiccups at all - just started those lovely sounding motors up and popped it up off the ground. Hover looked really nice and stable but I do have to get the gains dialed in a bit better tomorrow and the battery thresholds are all wrong. But woohoo! My first build and so far so good Will post some performance numbers once I have it dialed in a bit. Flying on the 14" props and 6S batteries right now - will hopefully have time to try the 17"/4S combo tomorrow too.

 

[SJBrit]

I had a peanut gallery for the maiden flight....

 

[Pumpkinguy]

Nice!

 

[SJBrit]

Super happy - test of the 14" prop, 6S configuration has me at 22mins hover time at 80% battery capacity. Right on target! Now to test the 17"/4S config.

 

[Pumpkinguy]

Can you explain to me why you are trying larger prop-less cells vs smaller prop-more cells. I don't understand. Thx

 

[Dawolf]

Nice thread, I've got a 650 too....my maiden flight did not go as well. got caught up in some wire I could not see...gotta replace my GPS mount and try again.

 

[SJBrit]

Can you explain to me why you are trying larger prop-less cells vs smaller prop-more cells. I don't understand. Thx

I'm really trying to push my flight time, so longer flights means large, slow turning props (for efficiency). So, the 17"/4S will hopefully be my default configuration. However, I also need it to fly in pretty decent wind and large, slow turning props are just not agile. That means I need a "windy day" config, or more accurately an "agile" config so it can deal with gusts - and that requires smaller, faster turning props. That's the reason for the 14"/6S config where 6S means 1.5x voltage which on the same motors means 1.5x RPM, and 14" props are much easier to accelerate (lower moment of inertia).

Make sense? I can explain in more detail if you like - I had to learn a lot to understand how all the parameters work together!

 

[SJBrit]

Nice thread, I've got a 650 too....my maiden flight did not go as well. got caught up in some wire I could not see...gotta replace my GPS mount and try again.

Ouch! Sorry to hear that. I am lucky enough to live on a horse farm so I went out into one of the pastures for an obstacle-free first flight!

 

[SJBrit]

Well, alright! That's 31 mins with the 17: props and 4S batteries - and SUPER quite: it's worth having that configuration just to hear it

That's the hover tests all done with - now to dial-in the gains properly - they are pretty close now. I'll also do some speed tests mainly to find out the limitations of these larger props.

Anyone know how I can edit my original post with the flight data? I don't see an edit button on that one anymore.

 

[Pumpkinguy]

I'm really trying to push my flight time, so longer flights means large, slow turning props (for efficiency). So, the 17"/4S will hopefully be my default configuration. However, I also need it to fly in pretty decent wind and large, slow turning props are just not agile. That means I need a "windy day" config, or more accurately an "agile" config so it can deal with gusts - and that requires smaller, faster turning props. That's the reason for the 14"/6S config where 6S means 1.5x voltage which on the same motors means 1.5x RPM, and 14" props are much easier to accelerate (lower moment of inertia).

Make sense? I can explain in more detail if you like - I had to learn a lot to understand how all the parameters work together!

kinda makes sense. Lol. So same size batteries in both cases but one is a 4 cell and one is a 6 cell? Didn't know one put out more voltage than the other.

 

[SJBrit]

Yes - each cell of a LiPo is about 3.7V so a 4S (four cell) is 14.8V and a 6S is 22.2V. For a motor its kV rating tells you RPM per volt, so with my 380kV motors:

• The 4S at 14.8V spins the props at 14.8x380 = 5,624 RPM (nominally - obviously that varies)
• The 6S at 22.2V spins the props at 22.2x380 = 8,436 RPM.

So that was my goal here - a slower spinning mode and a faster spinning mode. That's easy just by changing the batteries if the motors can handle that. It works nicely since the Naza PMU and Zenmuse GCU both take up to 6S voltage input at the BEC I got to supply 12V to the FPV Tx can take anything up to 8S. So, I can just change batteries and the only affect is that the props spin at a different speed.

 

[Pumpkinguy]

Thanks so much for the explanation. I am learning albeit slowly. Would you get even longer flight times with larger 4s batteries or would the extra weight negate any gains?

 

[SJBrit]

Thanks so much for the explanation. I am learning albeit slowly. Would you get even longer flight times with larger 4s batteries or would the extra weight negate any gains?

Yes, more battery = longer flight but you get into diminishing returns due to the extra weight. For example, if I went from 2x5.2A batteries in my performance config (6S) to 2x10A then eCalc tells me I might see a whole 90s extra flight time! Not worth it, particularly since that extra weight puts my hover throttle at >70% which massively cuts into its ability to maneuver rapidly.

So, it's a balancing act. Spend a LOT of time with eCalc before you plan a build - it's not always going to be exactly accurate (except it appears to have done a great job in my case) but it will help you understand the trade-offs as you vary the setup. For example, I could have gone with KDE's 4012 400kV motor instead of the 4014 380kVs. Who cares, right? they are so close. In fact, the 4012s would give me slightly more hover time, but I'm not in this to hover. If I am going to keep up with hounds and stay steady in the wind my motors are going to be working hard, and the 4014s give me 10% more efficiency at full throttle. So, it's not just a case of looking at the hover flight time when thinking about the nuances of your setup - how are you ACTUALLY going to fly? Then optimize for that.