DenisDespair
Member
If I have too much thrust, why not to eliminate it with some ballast, for example extra battery?
1st copter build (Tarot 680) - criticism needed
- Thread starter DenisDespair
- Start date
Motopreserve
Drone Enthusiast
Well, you could do that. But you would be fighting against weight to thrust ratio, which will most likely be less efficient.
The closer you design the craft to be at 50% hover - the more efficient the MR will be.
If you want the best flight times, adding weight will typically be your enemy.
The closer you design the craft to be at 50% hover - the more efficient the MR will be.
If you want the best flight times, adding weight will typically be your enemy.
AzViper
Active Member
Denis just remember even the best figuring of grams the finished build most likely will be slightly heavier. My current rig I am at 3686 grams. This is before my FPV equipment. The props / motors / voltage using KDE spec's I should develop 4040 grams of thrust at 50%. Currently I am within 9.5%. With the FPV I will arrive real close to my 50% hover.
This all looks good on paper but until the rig is placed on a scale who really knows the true flying weight, we can get close by all the spec's given by manufacturers, but we are at the the mercy of these figures of all parts that make up a multi-rotor. I have lots of room to go up or down with prop sizes.
This all looks good on paper but until the rig is placed on a scale who really knows the true flying weight, we can get close by all the spec's given by manufacturers, but we are at the the mercy of these figures of all parts that make up a multi-rotor. I have lots of room to go up or down with prop sizes.
Motopreserve
Drone Enthusiast
True. There is only so close you will get with the published data. And of course there is always something extra you decide to add on. But it doesn't hurt to get in the ballpark. I have yet to have an MR come in under the weight I estimated 
But i have also gotten pretty close by being diligent about compiling a list that includes as much data as I have available to me.
Best to err on the side of caution for sure. But having a decent idea of the overall weight definitely helps with the deign of the power required.
But i have also gotten pretty close by being diligent about compiling a list that includes as much data as I have available to me.Best to err on the side of caution for sure. But having a decent idea of the overall weight definitely helps with the deign of the power required.
AzViper
Active Member
True. There is only so close you will get with the published data. And of course there is always something extra you decide to add on. But it doesn't hurt to get in the ballpark. I have yet to have an MR come in under the weight I estimated
Best to err on the side of caution for sure. But having a decent idea of the overall weight definitely helps with the deign of the power required.
I totally agree having a spread sheet is needed. Getting a spread sheet together was the first item I did.
Motopreserve
Drone Enthusiast
Yep. Good to have so you feel somewhat confident.....before you add all the fun crap that throws the number out the window
AzViper
Active Member
So all this what weighs this and what weighs that got me thinking, I went out and bought me a Dymo digital postal scale today to find out my true weight. When I added up everything excluding the Gimbal and GoPro from my spread sheet my quad weighs 3411 grams.
Now I did not have my 4 spin off prop adapters, my extended 10mm rails, Y connector for the batteries, 20 inches of #14 silicone wire, foam under the batteries, braided loom, heat-shrink tubing, receiver antenna mount, and Velcro Straps listed in my spread sheet. When I placed the quad on the scale with everything mention excluding the DJI H3-3D Gimbal and GoPro 3+ the quad weighed in at 3458 grams. This is 47 grams over from the calculated weight due to the items in bold. I suspect these items in bold weigh more than 47 grams so some of the other items would appear to weigh less than the stated weight. With the DJI H3-3D and the GoPro 3+ the quad will tip the scale at 3720 grams plus maybe another 50 grams. My quad will be under by 670 grams under the 50% thrust of 4440 grams reported by KDE Direct.
Denis,
whats being stated for weights is damn close at least on the gear I am using. Honestly I am shocked by how close my spread sheet was. I had figured 3685 but the items in bold were not added and with a flying weight of 3720 I am off by 35 grams. Now that 670 grams will be eaten up with some of the other gear for FPV and Telemetry.
Now I did not have my 4 spin off prop adapters, my extended 10mm rails, Y connector for the batteries, 20 inches of #14 silicone wire, foam under the batteries, braided loom, heat-shrink tubing, receiver antenna mount, and Velcro Straps listed in my spread sheet. When I placed the quad on the scale with everything mention excluding the DJI H3-3D Gimbal and GoPro 3+ the quad weighed in at 3458 grams. This is 47 grams over from the calculated weight due to the items in bold. I suspect these items in bold weigh more than 47 grams so some of the other items would appear to weigh less than the stated weight. With the DJI H3-3D and the GoPro 3+ the quad will tip the scale at 3720 grams plus maybe another 50 grams. My quad will be under by 670 grams under the 50% thrust of 4440 grams reported by KDE Direct.
Denis,
whats being stated for weights is damn close at least on the gear I am using. Honestly I am shocked by how close my spread sheet was. I had figured 3685 but the items in bold were not added and with a flying weight of 3720 I am off by 35 grams. Now that 670 grams will be eaten up with some of the other gear for FPV and Telemetry.
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DenisDespair
Member
Well, I got estimated total weight (with camera, gimbal, electronics, FPV, props etc.) 5336 g in case of using MN4014 400KV motors and thrust 7.5 kg with 15*5 props. Seem to be an overkill with power. There is no data for this motor for smaller props.
In case of MT 4008 380KV total weight will be 5084 g ant thrust 5280 with 15*5 props. Seem to be fine. As AzViper has mentioned, there will be certainly a bit more weight due to wiring, velcro, etc.
In case of MT 4008 380KV total weight will be 5084 g ant thrust 5280 with 15*5 props. Seem to be fine. As AzViper has mentioned, there will be certainly a bit more weight due to wiring, velcro, etc.
Motopreserve
Drone Enthusiast
Sounds like that second choice makes the most sense. You really don't want to be 2kg thrust over AUW.
Seems like you're headed in the right direction.
Seems like you're headed in the right direction.
Motopreserve
Drone Enthusiast
I always find that strange too. SunnySky motors have some weird specs like that too - I assume it has to so with some loss of efficiency when the motor needs to torque a larger surface area???
DenisDespair
Member
http://www.rcgroups.com/forums/showthread.php?t=1896450&page=77 Here they claim that 15" is a limit for 810 frame, and 14" are better for stability
Sorry, I don't have a picture, but if you look to 2 nearest arms of hexacopter from the top, you get equal-sided triangle (since angle at the crossing of arms is 360/6=60 and 2 sides are obviously equal). Therefore, distance between centers of two neighbor props is equal to distance from prop center to construction center. I can't figure out what is it exactly, but it should be smth like 420 mm. 15"=381 mm, fine. 16"=406 - very close to clash.
Sorry, I don't have a picture, but if you look to 2 nearest arms of hexacopter from the top, you get equal-sided triangle (since angle at the crossing of arms is 360/6=60 and 2 sides are obviously equal). Therefore, distance between centers of two neighbor props is equal to distance from prop center to construction center. I can't figure out what is it exactly, but it should be smth like 420 mm. 15"=381 mm, fine. 16"=406 - very close to clash.
DenisDespair
Member
It would be an option to use MN4014 400KV , but they don't have specs for props smaller than 15"
Motopreserve
Drone Enthusiast
As a reference, Tarot 810 replacement booms are listed as 349mm.
AzViper
Active Member
PM Tim from this thread. He is using the MN4014 400KV motors but his copter is heavier and find out what props he is using. The reason I went with KDE is Chris will reply to all messages. I did not have any lucky getting T Motors to reply to emails. Maybe its time you look at KDE Motors. http://www.kdedirect.com/collections/xf-multi-rotor-brushless-motors
http://multirotorforums.com/threads/tarot-t810-build.20598/
http://multirotorforums.com/threads/tarot-t810-build.20598/
Motopreserve
Drone Enthusiast
I have a couple KDE powered MRs as well - and the customer service as well as the build quality and care is outstanding. Better efficiency will get you some more flight time.
Whole different price range though. But worth it in my opinion.
Whole different price range though. But worth it in my opinion.
Motopreserve
Drone Enthusiast
I was assuming 6S all along. Good find AZ! More options the better.
AzViper
Active Member
I have to agree, their customer service is the best in answering any questions and the quality is second to none...