Cyberdactyl
Misfit Multirotor Monkey
I'm back in business. Made the tweaks and printed a couple of templates.
The CyberQuad
- Thread starter Cyberdactyl
- Start date
Cyberdactyl
Misfit Multirotor Monkey
98% done cutting the carbon fiber. Just need to poke a few holes here and there for screws and zip ties, then start on wiring. It's going to be tight. But as promised, I'm going to have 3.5mm thick booms (2mm plate + 1.5mm thick shrink wrapped flat copper bar).
I loosely put together to see if it all fit. It's very tight, may even have to sand a slot and key here and there.
I loosely put together to see if it all fit. It's very tight, may even have to sand a slot and key here and there.
Cyberdactyl
Misfit Multirotor Monkey
The three shrink covered flat copper bars (just thin, narrow plate) is for power to the motors, not structural support. 2mm CF is easily strong enough.
Another stunning build CyberD. I can't wait to see this fly. 
Cyberdactyl
Misfit Multirotor Monkey
Thanks Cranial
After around 6 accumulated hours (three, 1-3 hour sessions) of cutting with a grout removal bit and going through about 8 of those very brittle, but very thin .025" thick cutting discs, and another hour of tweaking, I am done cutting the CF. I've discovered you have to be MUCH more precise cutting CF compared to G10. G10 will flex or give a bit at a connection point. Carbon Fiber is much closer to a theoretical perfect geometric surface. Much like steel in that what you cut is what you have to fit. This quad is held together by only seven fasteners. Most of the connections are slot and hole and perpendicular spline connections, and for those I have found you have to be darn near perfect. Using artist spray adhesive for the paper templates, the thickness of the drawn line can mean the difference between a slot being sloppy loose, or too tight to fit. Forcing isn't going to work outside of 0.1mm.
Below are the booms and clamping module. I've learned to angle my outside motor's ziptie slot slightly to pull the motor in, but not overly angled to put undo stress on the edge of the tie coming through the slot.
Top view
Bottom view
Bottom side view. You can see the bottom suspension bearings
Bottom view of the clamping module with the stabilization plate with the bearings
Fully assembled frame
Next I will start on the task of fitting the copper strips for the motor power connections. I'm putting off making the harness hoping for a ingenious design revelation. Otherwise, it's going to be quite a job fitting everything together while not transferring too much vibration across the wiring to the clean cage.
After around 6 accumulated hours (three, 1-3 hour sessions) of cutting with a grout removal bit and going through about 8 of those very brittle, but very thin .025" thick cutting discs, and another hour of tweaking, I am done cutting the CF. I've discovered you have to be MUCH more precise cutting CF compared to G10. G10 will flex or give a bit at a connection point. Carbon Fiber is much closer to a theoretical perfect geometric surface. Much like steel in that what you cut is what you have to fit. This quad is held together by only seven fasteners. Most of the connections are slot and hole and perpendicular spline connections, and for those I have found you have to be darn near perfect. Using artist spray adhesive for the paper templates, the thickness of the drawn line can mean the difference between a slot being sloppy loose, or too tight to fit. Forcing isn't going to work outside of 0.1mm.
Below are the booms and clamping module. I've learned to angle my outside motor's ziptie slot slightly to pull the motor in, but not overly angled to put undo stress on the edge of the tie coming through the slot.
Top view
Bottom view
Bottom side view. You can see the bottom suspension bearings
Bottom view of the clamping module with the stabilization plate with the bearings
Fully assembled frame
Next I will start on the task of fitting the copper strips for the motor power connections. I'm putting off making the harness hoping for a ingenious design revelation. Otherwise, it's going to be quite a job fitting everything together while not transferring too much vibration across the wiring to the clean cage.
What does this thing weigh?
Cyberdactyl
Misfit Multirotor Monkey
With the PZ0420 on it... it's 166g. The camera is somewhere around 15g.
I've tried to keep the weight down and used 2mm plate throughout. With the FCB, battery, camera and ESCs riding on a full floating cage, I feel it's not bad.
As I've always said, if the weight can't be kept very similar to a regular multirotor of similar size and function, going to the trouble of having booms close to 100% TCE wouldn't be worth it.
I've tried to keep the weight down and used 2mm plate throughout. With the FCB, battery, camera and ESCs riding on a full floating cage, I feel it's not bad.
As I've always said, if the weight can't be kept very similar to a regular multirotor of similar size and function, going to the trouble of having booms close to 100% TCE wouldn't be worth it.
Cyberdactyl
Misfit Multirotor Monkey
Cyberdactyl
Misfit Multirotor Monkey
Here's a few pics of the fundamental aspect of my mini. To achieve the absolute highest thrust column efficiency, I'm using strips of brass with a shrink covering. I ran a bit of solder in the elbow of the 30 angle at the bullet to strengthen the insert tab connecting the bullet. The 30 degree bend is so the bullet doesn't pry the strip away from flush when adhered. It's under the motor so there's no impact on air flow.
I realize I'm only buying around 5% more TCE over a 10x10mm CF tube with the wires running inside, and maybe only 3% more over a round 10mm CF tube with a similar config, I'm curious of the ultimate functionality.
This technique, considering the mass is about break-even compared to simply running 16g wire across the booms, but I decided to go with 20g wire from the ESCs out to the strips. So they're a bit of overkill.
I realize I'm only buying around 5% more TCE over a 10x10mm CF tube with the wires running inside, and maybe only 3% more over a round 10mm CF tube with a similar config, I'm curious of the ultimate functionality.
This technique, considering the mass is about break-even compared to simply running 16g wire across the booms, but I decided to go with 20g wire from the ESCs out to the strips. So they're a bit of overkill.
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Cyberdactyl
Misfit Multirotor Monkey
Here's a few, quick poorly contrasted photos of the progress in the last couple days. Found a couple of two hour windows over the weekend to wrap up my soldering.
The harness complete. I originally was going to replace the 20g wire with 16g but had a growing worry I was going to overtax the AfroSlims unless I spent time meticulously exposing the FETS. Which worked out ok, since I ended up mounting the BEC externally on the ESC rack on the rear of the quad, blocking air to the ESCs. I originally wanted to put the BEC inside the clamping module, but it turned out it would have pressed the front boom motor wires and the control wires very tight up against sharp CF edges and screw threads. Just need to shorten the ESC control leads. I now wish I had used all one color shrink for the ESCs. I had the idea of being able to quickly differentiate what ESC was what by having left black, right red, which proved unnecessary, The harness is actually 'upside down' in the photo . . .
Here I have the ESCs mounted and the harness threaded through the clamping module, ready to contact cement the motor lead strips to the booms.
Pretty much done. Still need to attach the Vtx on the opposite side from the receiver. I'll tune it LOS first. . .
Without the Vtx the AUW with a 3S 1300 battery is ~592g. So it looks like it will ultimately be a hair over 600g. But I'm using some fairly stout 2208/8 2600KV motors with 0645 props.
Of course the main design consideration is the ultra thin booms in planform. The booms turned out thinner than I originally calculated. They are 2.93mm wide. I'm pretty sure I have the thinnest booms in planform yet seen on a multirotor. . .
I'll get some some much better photos and some flight video soon, and share a couple minor mistakes I made in the design implementation, along with some serendipitous positive aspects, that is IF it flies as good as I hope.
The harness complete. I originally was going to replace the 20g wire with 16g but had a growing worry I was going to overtax the AfroSlims unless I spent time meticulously exposing the FETS. Which worked out ok, since I ended up mounting the BEC externally on the ESC rack on the rear of the quad, blocking air to the ESCs. I originally wanted to put the BEC inside the clamping module, but it turned out it would have pressed the front boom motor wires and the control wires very tight up against sharp CF edges and screw threads. Just need to shorten the ESC control leads. I now wish I had used all one color shrink for the ESCs. I had the idea of being able to quickly differentiate what ESC was what by having left black, right red, which proved unnecessary, The harness is actually 'upside down' in the photo . . .
Here I have the ESCs mounted and the harness threaded through the clamping module, ready to contact cement the motor lead strips to the booms.
Pretty much done. Still need to attach the Vtx on the opposite side from the receiver. I'll tune it LOS first. . .
Without the Vtx the AUW with a 3S 1300 battery is ~592g. So it looks like it will ultimately be a hair over 600g. But I'm using some fairly stout 2208/8 2600KV motors with 0645 props.
Of course the main design consideration is the ultra thin booms in planform. The booms turned out thinner than I originally calculated. They are 2.93mm wide. I'm pretty sure I have the thinnest booms in planform yet seen on a multirotor. . .
I'll get some some much better photos and some flight video soon, and share a couple minor mistakes I made in the design implementation, along with some serendipitous positive aspects, that is IF it flies as good as I hope.
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592 grams, wow!
What do those motors weigh?
What do those motors weigh?
Cyberdactyl
Misfit Multirotor Monkey
The motors come in a 52g with prop and collet. Maybe a bit too stout for something in this class size. Had a bad T-storm tonight so I didn't get a chance at flying other than in the house a bit. It's hovering at around 40%.
Will the frame accomodate 6 1/2" or 7" rotors?
The purpose of the frame is to push air more efficiently. Since you have demon stout motors, why not cut down a 7" or 8" rotor and make it a demon chasin', samurai sword spinning, flying, warrior of the apocalypse and push some frickin' air.
Of course, there is always 4S too.
The purpose of the frame is to push air more efficiently. Since you have demon stout motors, why not cut down a 7" or 8" rotor and make it a demon chasin', samurai sword spinning, flying, warrior of the apocalypse and push some frickin' air.
Of course, there is always 4S too.
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Cyberdactyl
Misfit Multirotor Monkey
Since the motors are 2600kv, with 20(30) AfroSlims not in direct air, I'm a little worried pushing past 0645. I may find another location for the BEC so that worry is alleviated. I designed it so the ESCs would have plenty of air.
If it flies well, I can still put something like 3100kv Tiger motors on it with 0545's, a NAZE32 (have one coming around the end of the week), and some more expensive and smaller ESCs and shave off upwards of 130g. Maybe something like those KISS ESCs that FGA loves.
Another variable is, although I found and used even thinner brass strips that are 6.3mm x .53mm, they are still overkill for the "weak link" of 20g wire. I could save another ~10g of AUW by finding strips around the same thickness, but around 4mm wide. I should have compromised and bought some 18g.
And if I wanted a pure acro flyer, I could remove the cage, do the above, go to a 2S or a 800mAh 3S and shave off somewhere around 200g.
But this is a pure prototype that was fun to design and build, should have plenty of lifting capacity, so whatever performance I get out of it, as long as it flies, I'll be happy.
If it flies well, I can still put something like 3100kv Tiger motors on it with 0545's, a NAZE32 (have one coming around the end of the week), and some more expensive and smaller ESCs and shave off upwards of 130g. Maybe something like those KISS ESCs that FGA loves.
Another variable is, although I found and used even thinner brass strips that are 6.3mm x .53mm, they are still overkill for the "weak link" of 20g wire. I could save another ~10g of AUW by finding strips around the same thickness, but around 4mm wide. I should have compromised and bought some 18g.
And if I wanted a pure acro flyer, I could remove the cage, do the above, go to a 2S or a 800mAh 3S and shave off somewhere around 200g.
But this is a pure prototype that was fun to design and build, should have plenty of lifting capacity, so whatever performance I get out of it, as long as it flies, I'll be happy.
Hey Cyber,
Once you get the quad flying, do you think you can do some empirical tests and post the results. I would love to see the difference in hover times between your ultra slim arms and arms that are 20 mm wide or so. Perhaps you could test it by taping 20mm wide strip cardboard to the arms and comparing hover times to your ultra slim arms.
I am also trying to design a small but long flying quad frame, and I would be really interested to see how the numbers come out. I calculated before that on a 5 inch prop, the loss due to 20mm wide arm is approximately 8-9% in efficiency. Your design would result in 1-1.5% loss. So, that's a 7-8% gain in efficiency. My calculations are based on 12,668 sqmm thrust area of a 5 inch prop minus 452 sqmm for the motor diameter of 24mm. A 22mm arm takes up 1070 sqmm of thrust area vs. just 161 sqmm for your design.
If you get a chance, it would be interesting to see what the data shows.
Once you get the quad flying, do you think you can do some empirical tests and post the results. I would love to see the difference in hover times between your ultra slim arms and arms that are 20 mm wide or so. Perhaps you could test it by taping 20mm wide strip cardboard to the arms and comparing hover times to your ultra slim arms.
I am also trying to design a small but long flying quad frame, and I would be really interested to see how the numbers come out. I calculated before that on a 5 inch prop, the loss due to 20mm wide arm is approximately 8-9% in efficiency. Your design would result in 1-1.5% loss. So, that's a 7-8% gain in efficiency. My calculations are based on 12,668 sqmm thrust area of a 5 inch prop minus 452 sqmm for the motor diameter of 24mm. A 22mm arm takes up 1070 sqmm of thrust area vs. just 161 sqmm for your design.
If you get a chance, it would be interesting to see what the data shows.
Cyberdactyl
Misfit Multirotor Monkey
Awesome you ran some numbers.
I decided to get a bit more serious and build a bench rig with a gram scale, watt & amp meter and a tach.
But the prop is a variable that really varies the results for the area close to the motor. For example the Blackout has a slight tapered flat boom and as it gets close to the motor and becomes more narrow, yet has a fairly wide mounting area. A prop that gets most of it's lift towards the outer radius will, on one hand, be detrimental in TCE to the widened plate near the frame, yet will show almost no loss for the wide platform under the motor. On the flip side, a prop with a parallel width and a constant camber will see the drawbacks to both aspects of the boom.
But again, as you have found, we're talking efficiencies that vary by 20% at the extremes, yet in most cases the variation is only ~15% between a CF tube and a CF plate laid flat, and then throw into the mix, all the subjectivity of prop choice. So I can understand why most designs blow off tweaking TCE, and design for a robust boom over squeezing out another 10%.
I will probably write it all up for an FT article so it will make me be clean and concise with proper scientific method.
I decided to get a bit more serious and build a bench rig with a gram scale, watt & amp meter and a tach.
But the prop is a variable that really varies the results for the area close to the motor. For example the Blackout has a slight tapered flat boom and as it gets close to the motor and becomes more narrow, yet has a fairly wide mounting area. A prop that gets most of it's lift towards the outer radius will, on one hand, be detrimental in TCE to the widened plate near the frame, yet will show almost no loss for the wide platform under the motor. On the flip side, a prop with a parallel width and a constant camber will see the drawbacks to both aspects of the boom.
But again, as you have found, we're talking efficiencies that vary by 20% at the extremes, yet in most cases the variation is only ~15% between a CF tube and a CF plate laid flat, and then throw into the mix, all the subjectivity of prop choice. So I can understand why most designs blow off tweaking TCE, and design for a robust boom over squeezing out another 10%.
I will probably write it all up for an FT article so it will make me be clean and concise with proper scientific method.
stay-fun
Helicopter addict
Those are some neat numbers, and I'm very curious about the results if Cyber can make the measurements! Very interesting.
Cyber, what is TCE?
And yes the prop does matter, but I guess these measurements need to be done 'ceteris paribus', or 'all else being equal'. So, start with a fresh battery, do the hover test with the extra cardboard on the booms for the extra drag, then mount the same cardboard on the top of the frame (so the weight will be equal) and do the measurement again.
It's a neat little quad, dude!
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