Extra long F550 arms.

[aForcefulThrust]

The parts are already delivered, but I won't be able to mess with it until Wednesday or Thursday. Using 2x 5000mah 20c zippy flightmax batteries. If I have enough lift, I might try using 4x5000mah packs just to see my flight times. Will post results then

 

[HighGainTuning]

I have the RCTimer 800 arms..... but haven't used them yet....

How much do they flex vs the F450 arms?
Keeping in mind some flex is good.

 

[gtranquilla]

Because the RCT800 arms have a raised center rib, they were designed to minimize flex for both span and weight or thrust of the motors.
I just tried to flex them and they "seem" stiffer than the F550 arms from a personal perspective......F550 arms are same as F450 I believe.
But that is a subjective assessment as I do not have access to lab equipment for testing flex/rigidty.
The other thing to keep in mind is torsional rigidity..... it seems that the RCT800 have a bit more torsional flex than do the F550 arms.
Obviously the optimum structure is a tube and an appropriately sized carbon fiber tube provides much higher rigidity in both dimensions!!!

How much do they flex vs the F450 arms?
Keeping in mind some flex is good.

 

[Kilby]

These have been out a while now. Anyone having issues with them?

I'm using them. They seem pretty solid with very little flex. I'm still on 4S with Avroto motors spinning 12inch APC props. This set up works great.

View attachment 10092

View attachment 10093

 

[HighGainTuning]

I'm using them. They seem pretty solid with very little flex. I'm still on 4S with Avroto motors spinning 12inch APC props. This set up works great.

View attachment 12937

View attachment 12938

Thanks for the comparison pic. That really shows the difference.
What landing gear set is that?

Are there any US suppliers stocking the extensions?

 

[helloman1976]

Check this out guys
http://www.rctimer.com/index.php?gOo=goods_details.dwt&goodsid=845&productname=
View attachment 10628

Looks pretty cool... I would get them if I could somehow mount my AVroto's to them, but the holes are off. Avroto is 19 and 25mm holes..

Opinions?

When is someone going to make some out of aluminum? If someone wants to manufacture something like this, make them out of aluminum and watch them fly off the shelf. The longer these plastic pieces get the worse the wobbles will get as they twist and bend pretty easily. Aluminum...it's what's for...well not dinner but FPV

 

[PeterLester]

Here are some of the specific gravities of various Polymides as used for many Multirotor arms.
Polyamide
PA-12 1.02 g/cm[SUP]3[/SUP]
PA-11 1.04
PA-6 1.12-1.13
PA-66 1.13-1.15

And the specific gravity of aluminum and most of it's alloys is:
2.70 g/cm[SUP]3 Much heavier than polymide, plastic, carbon fiber and plywood![/SUP]

When is someone going to make some out of aluminum? If someone wants to manufacture something like this, make them out of aluminum and watch them fly off the shelf. The longer these plastic pieces get the worse the wobbles will get as they twist and bend pretty easily. Aluminum...it's what's for...well not dinner but FPV

 

[Kentjjl]

Stop talking about them and show some video.

 

[HighGainTuning]

When is someone going to make some out of aluminum? If someone wants to manufacture something like this, make them out of aluminum and watch them fly off the shelf. The longer these plastic pieces get the worse the wobbles will get as they twist and bend pretty easily. Aluminum...it's what's for...well not dinner but FPV

To CNC those out of Aluminum would be very pricy, even in volume. I may take one to my CNC friend just to see what he would charge... The added weight needing larger motors would only be beneficial in stronger winds. I am sure the vibration resonance would also be increased based on the amount of bracing used.

I ordered 6 for my F550 today. I do not like the white or the pale red arms DJI supplies so these should be a nice replacement.

 

[helloman1976]

Here are some of the specific gravities of various Polymides as used for many Multirotor arms.
Polyamide
PA-12 1.02 g/cm[SUP]3[/SUP]
PA-11 1.04
PA-6 1.12-1.13
PA-66 1.13-1.15

And the specific gravity of aluminum and most of it's alloys is:
2.70 g/cm[SUP]3 Much heavier than polymide, plastic, carbon fiber and plywood![/SUP]

I guess I forgot to mention, who cares? If they're aluminum can you put bigger motors on them without worry? Yep... If they weight more can you prop up or go with bigger motors? Yep... We have 10lb hexacopters in this forum. When someone makes the aluminum arms, just like they did with the Quad model, then people will buy them. It really doesn't matter if they are 1 oz heavier each or not. I have a 900mhz 1.5W transmitter on my little bitty F550 and I can still carry 10 beer cans. Someone make them already so we can buy them.... I'd think the biggest concern is that your arms would now be conductive versus plastic which will not ground.

 

[HighGainTuning]

Someone make them already so we can buy them....

What would you expect to pay for a pair CNC'd out of 6061 aluminum?
If I were to do the CAD files which saves a bunch on the overall cost, I would expect any milling company to come back with a quote in the $40-$50 an arm range. Compared to $6.50 each that's a tough sell and that's no mark-up.

 

[helloman1976]

What would you expect to pay for a pair CNC'd out of 6061 aluminum?
If I were to do the CAD files which saves a bunch on the overall cost, I would expect any milling company to come back with a quote in the $40-$50 an arm range. Compared to $6.50 each that's a tough sell and that's no mark-up.

Considering I go through a few arms every couple of months at $4.50 + $2.00 shipping and that an aluminum arm would not break I'd pay a premium for a premium part. Check this out, there are carbon fiber propellers that people pay $20 each for so don't be shocked if they fly off the shelf. Also consider that you can make them longer, which people ALSO want and is NOT AVAILABLE right now without some garbage CNC plate extension. How about 650mm arm replacements so we can spin 12" or 14" props or whatever? There are many things you can do here, get creative and you can charge a premium. I'd probably pay $25 an arm to be realistic and $30 and arm for the extended version. Again, cast them if it's cheaper...make them out of tin...I don't care as long as they are hard, stable and won't break.

Or even better, how about a carbon fiber tube conversion kit for the View attachment 10126 550 where you only make the CNC aluminum piece that goes between the 2 DJI F550 plates where you can put the carbon fiber rod of your choice in there. Just my thoughts...

And they can't be that expensive or other companies would not be making them and selling them already... Here's the QAV500 aluminum arm replacements and they are $22 each so it can be done cheap.

http://www.getfpv.com/qav500-replacement-aluminum-arm.html

 

[HighGainTuning]

Based on the low gloss, that arm looks to be cast with some CNC work. Very cheap and also very easy to snap.
I wouldn't send my CAD files to South China so there is no way to get 6061 arms CNC'd for $25.00. The reason why we don't see them is because of their cost. I am sure there are many machinist on this forum that can share their 2 cents on milling cost.

 

[helloman1976]

Based on the low gloss, that arm looks to be cast with some CNC work. Very cheap and also very easy to snap.
I wouldn't send my CAD files to South China so there is no way to get 6061 arms CNC'd for $25.00. The reason why we don't see them is because of their cost. I am sure there are many machinist on this forum that can share their 2 cents on milling cost.

Welcome to Capitalism, first person to make them will get the business. China, India, USA...won't matter...can't afford the cost to manufacture, not our problem because China will and that's how things work. The second they hear wind of it, they'll mass produce them and send them here and they'll sell. This is the way things work, hope you can find a better, cheaper, stronger way as we'd all love to buy American made but alas...39 cent per hour labor is hard to compete with. I guess QAV500 will be the only one with aluminum arms then. Does anyone own one of these? Do they snap easily? Are they full on aluminum or that pressed powder crap? Either way, they're better than wobbly plastic that breaks when you sneeze on it.

How about some CNC aluminum blocks that go between the DJI F550 plates so you can replace the arms with carbon fiber ones? Like this...

http://www.foxtechfpv.com/product/Quadcopter/tarot/tarot 8.jpg

 

[olof]

I make camera parts and much simpler parts than those arms sell for about $100.00, now we only make batches of 100 or so, these are pretty specialized.

I personally don't think aluminum is a good way to go. It bends very easily, even the 7000 series (harder than the standard 6061 T6 I use most of the time). In a crash that would not even break the plastic arms the aluminum would bend and the geometry would change.

I may make some custom arms at some point for my F550 and my S800, if I do I will post here. And I would definitely use carbon fiber with aluminum or carbon fiber ends. I doubt I could make the arms of composite and aluminum for less than $100.00 per arm, unless I made thousands of them. And I have no interest in that. There is no economical reason for me to do this it would just be an interesting experiment.

The thing is I would probably make a complete MR from scratch instead, and there is no way I can compete on price with the current options out there. These things are ridiculously cheap. And they work remarkable well.

 

[helloman1976]

I make camera parts and much simpler parts than those arms sell for about $100.00, now we only make batches of 100 or so, these are pretty specialized.

I personally don't think aluminum is a good way to go. It bends very easily, even the 7000 series (harder than the standard 6061 T6 I use most of the time). In a crash that would not even break the plastic arms the aluminum would bend and the geometry would change.

I may make some custom arms at some point for my F550 and my S800, if I do I will post here. And I would definitely use carbon fiber with aluminum or carbon fiber ends. I doubt I could make the arms of composite and aluminum for less than $100.00 per arm, unless I made thousands of them. And I have no interest in that. There is no economical reason for me to do this it would just be an interesting experiment.

The thing is I would probably make a complete MR from scratch instead, and there is no way I can compete on price with the current options out there. These things are ridiculously cheap. And they work remarkable well.

So that's where we are and I hope this doesn't also speak volumes about manufacturing in America versus China and the state of the country etc. Anyway, I don't think making JUST THE aluminum block should be very expensive though right? All we'd need is a part to go between the 2 DJI F550 plates, we can get the carbon fiber rods cheap and easy and it would be a simple swap I'd think. What is the main factor behind the cost? Is it labor, design or the cost of the ingots or what? Sounds like it's time to bring back TORLON lol...

 

[HighGainTuning]

How about some CNC aluminum blocks that go between the DJI F550 plates so you can replace the arms with carbon fiber ones? Like this...

http://www.foxtechfpv.com/product/Quadcopter/tarot/tarot%208.jpg

That would be very do-able but you want some flex and you want something cheap to break.

 

[helloman1976]

That would be very do-able but you want some flex and you want something cheap to break.

Yeah, not really...don't want any flex at all and I'd rather have carbon fiber rods myself. The blocks would allow me to cut carbon fiber arms to the length I want and there are plenty of motor mounts already out there made out of anodized aluminum. What I don't like about the F550 is the fact that the arms flex and move about which causes vibrations throughout the frame. I can hand twist my motors 10-15 degrees at any point in time whereas with a carbon fiber rod that will not happen, it'll either not bend or snap. How much are we talking for a set of 6? What do you think you could make those for? We're talking about just the aluminum blocks. I'm curious how much interest there would be from other DJI F550 users as well. The big advantage is being able to pick your arm length and thus your propeller size and the total diameter of your F550 and maybe someone out there wants it smaller, who knows but you'd have that option. Let me know...thanks for taking the time to explain everything.

 

[HighGainTuning]

If you have owned any Multicopter with CF rods you know they twist with just a small impact and you don't want 6 motors vibrating into an IMU. It is not good for the electronics or telemetry.That is why you are seeing all the isolation on the mounts today.
I could probably get mounts milled for $15.00 each in volume. Add your own 16mm CF tubes and purchase any of the engine mounts already on the market or have some of those milled that will accept the integrated ESC's

 

[helloman1976]

If you have owned any Multicopter with CF rods you know they twist with just a small impact and you don't want 6 motors vibrating into an IMU. It is not good for the electronics or telemetry.That is why you are seeing all the isolation on the mounts today.
I could probably get mounts milled for $15.00 each in volume. Add your own 16mm CF tubes and purchase any of the engine mounts already on the market or have some of those milled that will accept the integrated ESC's

Fascinating, ok so what do you consider to be "volume"? 10? 100? 1000?

I mount everything on my multicopter on this cool foam pad stuff I used to use to stabilize my helicopter gyros, works like a charm. My video transmitter, my flight controller, my L-C filter and even my voltage regulator are all on this foam pad stuff. It's does an amazing job of keeping the vibration out but keeping the flight controller stable and unable to move. I'd do the exact same thing with CF arms and the difference would be there would be no deflection anymore. Since the arms are round I can then mount legs to them easily with a simple clamp. It's brilliant, I hope someone pumps these out. I was considering moving to the Tarot FY680 but this could save me some money...maybe?

http://www.foxtechfpv.com/tarot-fy680-cf-folding-hexacopterpreorder-p-810.html