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May 02, 2021, 01:54 AM
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Discussion

What size frame for a quad to carry gimbal + go pro


Hi, I've found a controller (Matek H743) which looks suitable for arducopter, now I am looking at what size frame to get for carrying a go pro with gimbal, what size esc's, what size motors, battery? I'm completely unsure of how you work out what size you need. Preferably a frame with landing legs.

I want to do photogrammetry and photography with it. I've found a project with an ESP32 using wifi to control the gopro which should interface to the h743 for camera trigger ability. It will possibly be carrying FPV gear from go pro or at least a remote base station to see where it's aiming if possible. FRSKY R-XSR receiver or eventually maybe crossfire if I really get into it. Preferably not too expensive but I have a feeling this project will burn a deep hole in my pocket. TX16S Max transmitter.

I think the gimbal will be a Tarot TL3T05 unless better/cheaper is available.

Thanks.
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May 04, 2021, 10:41 AM
FA3PR9WM79
Oldgazer's Avatar
Here are the specs for my stretched 650 Sport:

Tarot 650 Sport Stretched to 682mm

Take Off Weight (TOW)(g) 3591

Battery Capacity (mAh) 10000
Number of Cells 6
Battery Weight (g) 1200
Battery energy density (Wh/kg) 185


Number of Motors 4
Thrust per Motor (g) 897.75
Watts per motor 84.753
Motor Efficiency (g/W) 10.5925453966

Expected Flight Time (minutes) 39.290644579
Flight Time with 20% Reserve 31.4325156632

Aircraft Dry Weight (g) (No Battery) 2391

Pixhawk w/GPS
3DR 915mHz Telemetry
TIY-Motor 5008-335Kv Motots
T-Style 1755 CF Props
Tarot Retracts
FlyTron Navigation Strobes
Yaapu Telemetry
6S +12 volt BEC
6S +5 volt BEC
OLED Display
3 Axis Gimbal w/ STorM32 Controller
GoPro Hero 3+ Black
Tarot "Carbon Look" Canopy
MavLink OSD running MWOSD
200mw FPV Video Transmitter
RHCP Clover Leaf Video Antenna
MAUCH HS Series 100A Current sensor.
MAUCH 2S-6S +5 volt BEC.

NOTES:

1. Stretched using stock arms from a Tarot 680 Pro Hex.

2. Replaced the stock motor mounts with CNC aluminum mounts. This is only an example. There are multiple vendors and multiple styles. the key point is to choose mounts for 16mm tubes and a through bolt in the tube clamp. This bolt goes through the tube and prevents the mount from shifting.

3. Motors were also sourced from AliExpress . Make sure you choose the 335Kv version.
May 11, 2021, 12:03 AM
Registered User
Thread OP
Thank-you. Do you think a 450size frame would be enough to hold it? 3s? Or do I need 550 and 6s?
May 11, 2021, 07:03 AM
FA3PR9WM79
Oldgazer's Avatar
Baring external obstructions, a 450 quad frame limits you to using 12" props. A 550 hex limits you to 10" props.

This puts your motor choices into the 900 to 1100Kv range using 3S batteries.

I started out with a cheap quad frame. It was fine for learning, but as a camera platform it sucked so I went with a Tarot 680 Pro.

The Pro was better, but I just couldn't get the flight time I wanted, so I built and stretched a 650 Sport.

After trying 3 different motor sizes (5010-530Kv, 5010-350Kv, and 5008-335Kv) and 5 different prop types an sizes (Tarot 15" and 16" folding, "regular" 15" and 16" carbon fiber T-Motor style, and 17" thin "fat root/narrow tip" T-12 style), the configuration that gave the best endurance was 5008-335Kv swinging 17" "fat roots" on 6S.

After I stretched the 680 Pro to 812mm this is what I wound up with:


Tarot 680 Pro Stretched to 812mm

Take Off Weight (g) 3641
Battery Capacity (mAh) 10000
Number of Cells 6
Battery Weight (g) 1220
Battery energy density (Wh/kg) 181.9672131148

Thrust per Motor 606.8333333333
Motor Efficiency (g/W) 9.8945594869
Expected Flight Time 36.1976194358
Flight Time with 20% Reserve 28.9580955487
Watts Per Motor 61.33

680 Pro Bare Weight (No LiPo) 2421
X-Nite 5010-350Kv motors
15 x 5.5 CF Props
X-Rotor 40A OPTO ESCs
Pixhawk 2.4.8 Flight Controller
915mHz Telemetry
FrSky X8R
Tarot 'Small' Retracts
SJ4000 'clone' camera
2 Axis Gimbal w/8bit SBGC
Multistar 6S 10000mAh 10C
May 11, 2021, 11:27 AM
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Thread OP
Thank-you very much for the help, your posts are very in depth and great for me to learn. Would a 550 3s be ok for a camera platform? 3 axis gimbal + retractable landing gear. 6s is starting to get outside my price range, $150aud for a battery :O lol.

On the amazon page for TAROT 650 Carbon Fiber 4-Axis Aircraft Fully Folding FPV Drone UAV Quadcopter Frame Kit for DIY Aircraft Helicopter TL65B01 they say - Special recommendation: for Gopro

180-250W motor+20A ESC+4S 5000 battery+10-12 inches propeller

Would that work? Much more affordable battery.
May 11, 2021, 01:26 PM
FA3PR9WM79
Oldgazer's Avatar
Probably not. Some idiot sales person wrote that description.

A stock 650 has enough room to swing 15" props. Going smaller is a waste.

I can see where you are going with this, but to be honest "going cheap" is actually more expensive in the long run than it is to go with proper motors and props.

Case in point:

My 680 Pro was a ARF (Almost Ready To Fly) kit that included 13" props, 4006-620Kv motors, and Hobby wing X-Rotor ESCs. The motors were crap so I went with some Multi Star Elite 4006-740Kvs from Hobby King. Much better motors. Life was good.

The I started trying to figure out how to get better flight times, and no matter what I did, nothing really worked. I couldn't' use longer props, and even on 6S, with lower KV motors the differences in flight times were under 2 minutes. Finally I got the hint: Prop size and motor size and Kv matter...

Look at the specs that I posted. The aircraft differ by about 100 grams in weight. The real difference is in the motors and the props. The 5010s work really well with 15" props, but they suck with anything larger. On the other hand, the 5008 motors love 17" and 18" props and hate anything 16" and smaller.

Here's another clue for ya: 99.999999% of the ARF kits and some of RTF (Ready To Fly) bundles use cheap parts, particularly ESCs, motors, and props. My first quad was an ARF with generic 30A ESCs, generic 2212-1000Kv motors(which are better suited of an airplane), and generic 1045 plastic props. It also had a bare bones flight controller. It flew ok, but is was not a good camera platform.
May 13, 2021, 11:55 AM
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Thread OP
How about 6s 5000mah? What kind of flight time for that?
May 13, 2021, 12:33 PM
FA3PR9WM79
Oldgazer's Avatar
Quote:
Originally Posted by Archades
How about 6s 5000mah? What kind of flight time for that?
Going 6S on small frames like that is entirely counter productive because you cannot use the larger sized props and lower KV motors that using 6S requires.

Here is the logic:

Frame size locks you into a specific prop size range.

Prop size locks you into a specific motor KV range.

Motor KV range locks you into a specific battery cell count.

This is how it is and there is no way around it.

The sad thing is practically every beginner (including myself) makes this same mistake: They do not build the aircraft to fit the intended mission. Instead, they build something small and inexpensive and then they waste time and money trying to get the aircraft to do things that it simply cannot do.

My advice:

1. Learn to take NO for an answer.
2. Define the mission FIRST and be specific.
3. Read
4. Research
5. Read some more.
6. The Laws of General Physics have not been repealed.
7. Learn how things work and learn why these things work the way they do.
8. Save money. You're gonna need it.
9. Do not buy a cheap Chinese ARF kit.
May 16, 2021, 08:34 AM
Registered User
Thread OP
Oh I meant on your flying quad that you have now, the bigger one with the 10000mah. What's the difference between 10000 and 5000? I may have some 6s 5000s available.
May 16, 2021, 09:00 AM
FA3PR9WM79
Oldgazer's Avatar
Quote:
Originally Posted by Archades
Oh I meant on your flying quad that you have now, the bigger one with the 10000mah. What's the difference between 10000 and 5000? I may have some 6s 5000s available.
Since I do not have a 5000mAh battery I have never tested it.

One could easily assume it would be 1/2 that of the 10000mAh, but it doesn't work that way.

The aircraft would be lighter by about 600 grams, so hover current would be lower which would tend to extend the flight time to just over 1/2 of that with a 10000 mAh battery.

However there is a big problem.

The aircraft will be over powered so the stick travel between full low and hover would be less that that with the heavier 10000 mAh battery. This would make take off, landing, hovering and AltHold more difficult to control. This will effect RC and Flight Controller throttle control. The aircraft may be unflyable...
May 16, 2021, 04:55 PM
Registered User
Thread OP
Quote:
Originally Posted by Oldgazer
Since I do not have a 5000mAh battery I have never tested it.

One could easily assume it would be 1/2 that of the 10000mAh, but it doesn't work that way.

The aircraft would be lighter by about 600 grams, so hover current would be lower which would tend to extend the flight time to just over 1/2 of that with a 10000 mAh battery.

However there is a big problem.

The aircraft will be over powered so the stick travel between full low and hover would be less that that with the heavier 10000 mAh battery. This would make take off, landing, hovering and AltHold more difficult to control. This will effect RC and Flight Controller throttle control. The aircraft may be unflyable...
Could you set throttle to say 70% to compensate? I'm not sure how throttle works on quads, is it altitude is set exactly to throttle percent or is it like mid stick = stay at altitude, and then up or down raises or lowers altitude and centering keeps that altitude?

I may have 2 6s 5000's, have to check what my brother has.


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