R&D Hex for Survey/Imaging/Conservation

[fltundra]

How so? Here is what I get with 3510 475kv:
View attachment 24679

and changing nothing else I get this with 3520 400v, far lower temp suggesting better efficiency, no? Am I missing something?

View attachment 24678

A lot has to do with the way you enter the numbers. As when I run the numbers on my rig they are way off, until I drop the Pconst: to around .9 using tmotor cf's. The apc's and beechwoods i tried I didn't have to change it. Tmotor cf's are at least 1 amp or more better efficiency in hover with mine.
You won't go wrong with the 400's either.

 

[crayfellow]

A lot has to do with the way you enter the numbers. As when I run the numbers on my rig they are way off, until I drop the Pconst: to around .9 using tmotor cf's. The apc's and beechwoods i tried I didn't have to change it. Tmotor cf's are at least 1 amp or more better efficiency in hover with mine.

that's interesting - so for APC or Xoar beechwood, the preset PConst should be correct, but for T-motor cf it should be overridden to a custom prop with a PConst of 0.9 or so?

It just seems like even with 14" prop, ecalc is saying the 3510 is overworking just a bit. And I want to avoid "needing" a specific prop/material. But again maybe I'm misreading it. Even if I change Model Weight to 1 gram it says the 3510 will overheat clearly I'm missing a detail here.

 

[Mactadpole]

You can easily put 16" on those 400mm arms. I'm doing it. Try ecalc with the 3520's and 16" props to see what you get.

Keep in mind you will never be running at full throttle. Do you live in a hot part of the country though?

 

[crayfellow]

You can easily put 16" on those 400mm arms. I'm doing it. Try ecalc with the 3520's and 16" props to see what you get.

Keep in mind you will never be running at full throttle. Do you live in a hot part of the country though?

one of the coldest! MN, although it gets hot here in the Summer. Yeah I always try both 15 and 16. 16 looks great on 3520 400kv, pretty much the same only with more flight time. No harm in trying it with some APC's.

*seems* to my untrained eyes like 3520 is the only way to go with this rig. I realize I'll never run at full throttle but the temp numbers are so radically different vs. the 3510 that it seems to justify the moderate cost difference (again, unless I'm missing something; I realize there are almost innumerable variables at play).

Unrelated note, 3DR apparently has a perpetually crashing or overloaded e-commerce platform so it was impossible earlier this week to order anything. I was already poking around for u-blox M8N GPS (the 3DR GPS is the much older and far less accurate u-blox 6), and rctimer had it while no US-based shop did. So I grabbed a "Fixhawk" along with it, and it is working out just great for $50 less. I'm not sure why people call these "clones" since it's open hardware, but I digress.

 

[Mactadpole]

Here's a pic with 16" props on 400mm arms. Sorry I didn't have the props tip to tip but there is plenty of distance between them. I got in a flight today and these made a huge difference in vibrations. I have been studying the 15" CF props I have and they are just terrible, even the props tips track up to 7mm off. I really wish the balance on these wood hiprop brand were better because I would probably stick with them. I started adding tons of CA to sides of hubs and got tired of doing it so I just busted the dremel out and had to remove a ton of material. Now I don't feel safe to fly with them on a regular basis but it was good to use them for testing. I hope the APC's are better but now I'm back to considering the KDE triple prop adapters. I think on these big props you get what you pay for.

I'm sorry I can't really help you on the 3510/3520 decision as I haven't used KDE. If it were me I would probably go with the 3520's myself, but that doesn't mean its the right decision.

View attachment 24684

 

[Motopreserve]

Where did you get the CF props that are that off? I got some decent ones from AddictiveRC (he specifically said the 15" were ok, but same brand of other size no good). Also, I think Range Video may sell some that are decent and reasonable.

 

[Mactadpole]

Where did you get the CF props that are that off? I got some decent ones from AddictiveRC (he specifically said the 15" were ok, but same brand of other size no good). Also, I think Range Video may sell some that are decent and reasonable.

http://www.himodel.com/plane/TOMO_S..._Efficiency_Propeller_Set_one_CW_one_CCW.html
same place I got the wood props.

 

[Motopreserve]

Wow. That is cheap. The ones I got were more than that - but not T-Motkr prices.

 

[crayfellow]

Here's a pic with 16" props on 400mm arms.

Cool - yeah I might as well start with 16" APC to see where that gets me (with 3520). Flight time should be pretty decent.

 

[crayfellow]

@Mactadpole I have an InfinityMR preordered. Do you think it is reasonable to drill mounting holes into the frame bottom plate for the standoffs, or to make an adapter of some sort to hang it lower? My concern with drilling holes arbitrarily would be throwing off CG/balance (I'm not working in a precision machine shop).

 

[Mactadpole]

@Mactadpole I have an InfinityMR preordered. Do you think it is reasonable to drill mounting holes into the frame bottom plate for the standoffs, or to make an adapter of some sort to hang it lower? My concern with drilling holes arbitrarily would be throwing off CG/balance (I'm not working in a precision machine shop).

I would wait until you get it. Although I don't think need to worry much about throwing off CG because you are going to have to mount it in the center of the bottom plate regardless. The only thing to keep in mind, it was mentioned earlier in the thread I believe, is that it is difficult to work in between the two center plates ones its put together. It is a bit of a time sink to have to take the center plates apart to do any work and then put it back together and realign everything. Not terrible but it will take a little time.

Are you going to mount batteries above on the Quadframe plate or do some other sort of mounting? I really like it better now that I cut that plate in half and mounted the batteries on either side of FC.

Since you will have a 3-axis gimbal what will you do about the landing gear? I am thinking of getting a set of retractable landing gear in the near future. I thought user Madmonkey had started a thread looking for a good set but I can't seem to find it right now.

Curious, did you get the InfinityMR with encoder motors and which controller? I am very eager to see the results for this gimbal from actual users.

 

[Motopreserve]

Mac is right. As long as you do measurements - all 4 holes should effect the CoG equally. It really should not make a difference anyway. You're drilling 3mm holes .

Definitely do it first. Taking it apart is a pain (any frame really).

 

[crayfellow]

OK, that makes good sense; I will wait. I have been thinking of the frame disassembly; that is one nice thing about having the "tubes" a la Tarot frames. I wonder what would be a simple way to have some sort of adapter between the frame and gimbal mount to avoid having to disassemble the frame to get access to the gimbal attachment (again, having no access to machine tools).

Yes @Mactadpole, I did get the encoders. I will do whatever I can to share my experience in order to help others benefit from it. There is so much "gimbal stuff" out there now but seemingly with a very poor signal/noise ratio (or bias), so real world honest to goodness experience will hopefully be a useful contribution to the greater community.

As for landing gear, I have 315mm QuadFrame light legs. For the vast majority [if not all] of my flight study I will be a sole operator, so I don't have much need for freely yawing the gimbal vs. simply yawing the craft. But if it becomes useful for survey, I definitely would be interested in exploring retractable options.

Battery, yes I have the QuadFrame battery plate. It is valuable to know your positive experience with putting halves alongside the FC plate; I will have to consider that.

 

[Motopreserve]

I think I'll be adding a rail system to the Quadframe quad I have to accept a quick release plate. Adds some clearance needed - but well worth being able to take off the gimbal.

 

[crayfellow]

I think I'll be adding a rail system to the Quadframe quad I have to accept a quick release plate. Adds some clearance needed - but well worth being able to take off the gimbal.

yeah - would you modify a Tarot one or make your own with CF tubes?

 

[Motopreserve]

Make my own. Not tough. Aluminum angle bar with holes drilled and add rubber grommets to the holes. Bolt it to the bottom plate and put some CF tubes in there. The QR mechanisms can be pricey. I got 4 from China for about $60 shipped for a project.

 

[crayfellow]

Make my own. Not tough. Aluminum angle bar with holes drilled and add rubber grommets to the holes. Bolt it to the bottom plate and put some CF tubes in there. The QR mechanisms can be pricey. I got 4 from China for about $60 shipped for a project.

(thinking about this more) The tube clamp-friendly mount for the InfinityMR is an additional $200 so I will need to determine if that is worth it, or if I could fabricate some simple alternative.

 

[Mactadpole]

(thinking about this more) The tube clamp-friendly mount for the InfinityMR is an additional $200 so I will need to determine if that is worth it, or if I could fabricate some simple alternative.

For what you get I don't think its too bad of an option. You could always get the Vulcan gear rail system to put on the copter that it would clamp to - http://www.rc-drones.com/Vulcan-12mm-Rail-Mount-System-with-Rails_p_658.html
Been toying with the idea of doing this myself and getting the Vulcan quick release plate.

Of course your going to have to figure out how to attach all this to frame and if there room to drill for required holes.

 

[Motopreserve]

I based mine off the Vulcan. That's what I have on my Vulcan frame- and the QR bolts broke under normal strain - which really pissed me off. I had to replace them with Allen head bolts - which makes it not so quick. And their pricing is high. So I decided to make my own.

The rail system is how I described above. The QR part is CF or G10 plate drilled to mount the QR mechanisms I got from China - say what you will, but they KILLED the English made Vulcan versions

The mounts to the frame can be any spacing that works with the lower frame plate. My next version will probably be made from 2 pieces of thick g10 bolted together to make the L shaped mount to frame. That way I can use PEM nuts on the L, and there will only need to be a short bolt down from the plate. Frees up space - gets rid of the need for nylocs and the extra length needed for the bolt.

 

[Mactadpole]

Alright here's a rabbit hole for you guys. Some related questions:

1. Many people power gimbal/vtx/etc. using a separate battery. For me if I'm buying expensive 6S batteries I'd like to keep it simple and just use BEC to power those, and I guess an LC filter to avoid noise. Am I missing something?
2. Assuming I run 6S (seems pretty well locked in at this point), I have a number of power considerations:
   1. Pixhawk power module: will require an Attopilot 180A module in the place of the standard one, so if I run 2x batts this would be on one of them as Mactadpole describes.
   2. Power for Pixhawk/Rx: should this be a separate BEC for redundancy?
   3. Power for 12V (gimbal, gimbal controller, Vtx): BEC or separate battery?
3. If I use Attopilot to pixhawk as power module should I also have Taranis voltage monitoring? Mactadpole I think you mentioned you have this on your "other" battery?

If we need 5V and 12V BEC, do we use the same unit for this, or separate? What are some that are known to be reliable? This seems extremely important to me since a failure could mean... failure.

Some answers for you:

1. I use an adjustable BEC (built into PDB board) to power the gimbal without a filter.
2. 1)It depends on how you feed the battery power to the PDB. Solder both battery wires together and then to Attopilot and you get it all through there. I don't like this setup because there is potential for the power module to fail and then it all falls out of the sky. Ask me how I know. I feed the battery wires separately to the PDB. One set goes through the power module and I just scale it in Mission Planner to show what is theoretically going through both. The other set I have going through the Frsky current sensor so I also get the voltage and current on the Taranis. I find the Frsky to be much more accurate. Yes this is more complicated, it provides redundancy while also creating a few additional failure points. Pick your poison. 2) I do have a 5V feed to the Pixhawk rail as redundant power from PDB BEC. 3) Your choice. I feed it from BEC because I don't like dealing with multiple batteries. I'm sure there are arguments against this.
3. Explained in #2.

I have a 5V and 12V built into the PDB I use (see build thread). You can of course use separate ones. Castle creations are the best IMO. In theory you should have good failsafe options with the Pixhawk and it will come home at the flip of a switch.