Benjamin Rowland
Member
We're currently running 40amp Turnigy Plush. We may switch to Castle Creations ESCs because their new firmware works well with Hoverfly.
Two clients want me to fly their RED EPIC cameras - advice?
- Thread starter Benjamin Rowland
- Start date
We're currently running 40amp Turnigy Plush. We may switch to Castle Creations ESCs because their new firmware works well with Hoverfly.
Ben I saw this and thought of you https://vimeo.com/44559081 I suspect you have already seen this. Might be worth contacting them for any tips if you havent seen it already
Cheers
mike
Cheers
mike
ChrisViperM
Active Member
Hi Gary
This is the hompage from the Hercules BEC's...they are from Canada and the stuff is also manufctured there. Great guys also if you need advice or support.
http://www.western-robotics.com/hercules_hp.html
Just check throug their website and Google with their article-number to find a supplier or web-shop near you.
Chris
Benjamin Rowland
Member
Yes, I should get in contact with them - thanks for the link. A few things I noticed from the video... They've got that Skyjib loaded up with batteries. Looks like they have some big motors too. And I need some of those groovy yellow cones.
Looks like bigger motors and some higher voltage batteries are in our immediate future.
Ben,
I have been flying the Epic for about the last year pretty regular on large SR helis. I have been flying these airframes for 10 years now so i have a very extensive preventive maintenance history/plan which has proven 100% reliable so far (knock on wood). I am intersted in a big multi also but the thought of it with these cameras really scares me!
I have been flying the Epic for about the last year pretty regular on large SR helis. I have been flying these airframes for 10 years now so i have a very extensive preventive maintenance history/plan which has proven 100% reliable so far (knock on wood). I am intersted in a big multi also but the thought of it with these cameras really scares me!
Chris,
I don't understand how "over-amped" ESCs could get too hot when operating well under their rating. I recently got 60A Turnigy Plush even though they will probably never see more than 30amp, as I wanted to be over conservative. Not the most efficient in terms of weight and power that I know. But getting too hot?
DucktileMedia
Drone Enthusiast
Yeah, I was wondering about this as well. I wasnt going to say anything since I am no pro on that stuff. But sounds iffy to me.
ChrisViperM
Active Member
Since my English is good for everyday use, but not good enough for explaining electronics, and all my web-links, which could explain the heat-issue in technical terms, are in German as well, have a read here:
http://www.andreasbaier.de/index.ph...s-escs/81-was-ist-eigentlich-aktiver-freilauf
http://en.wikipedia.org/wiki/Synchronous_rectification
or easier explained:
http://www.helifreak.com/showthread.php?t=278230 (Post #8)
http://www.andreasbaier.de/index.ph...s-escs/81-was-ist-eigentlich-aktiver-freilauf
http://en.wikipedia.org/wiki/Synchronous_rectification
or easier explained:
http://www.helifreak.com/showthread.php?t=278230 (Post #8)
Thanks for the links. I could not find any reference that would point to more over-heating when using larger esc's. Unless I missed something, all references to voltage drops in the links will lead to the same power losses (and possible over-heating) regardless of the amp rating of an esc (assuming same design) since those power losses depend on the current drawn, which depends on motors, weight, etc ... but not the esc
(for a given design, and except for its weight in the overall system).
The same can be said regardless of free-wheeling or "active" freewheeling (cool idea, ..).
In fact, given the fact that a higher current esc would typically have larger traces, larger leads, possibly more FETs in parralel, etc ... than a lower one, lower power losses would typically occur in many parts or the circuit ... The additional weight of larger ESCs, larger wires, etc ... will certainly offset that as this will increase current drawn. But in a 10 pound plus copter and given lower resistance of the wires, traces, etc ..., it seems it would be a wash or at worse negligible ... as long as the larger ESCs chosen are not adding "crazy" amounts of weight, of course ...
A small price to pay, for me at least, for added peace of mind.
Anyways, this thread is about the Epic, don't mean to hijack such a cool topic ....
(for a given design, and except for its weight in the overall system).
The same can be said regardless of free-wheeling or "active" freewheeling (cool idea, ..).
In fact, given the fact that a higher current esc would typically have larger traces, larger leads, possibly more FETs in parralel, etc ... than a lower one, lower power losses would typically occur in many parts or the circuit ... The additional weight of larger ESCs, larger wires, etc ... will certainly offset that as this will increase current drawn. But in a 10 pound plus copter and given lower resistance of the wires, traces, etc ..., it seems it would be a wash or at worse negligible ... as long as the larger ESCs chosen are not adding "crazy" amounts of weight, of course ...
A small price to pay, for me at least, for added peace of mind.
Anyways, this thread is about the Epic, don't mean to hijack such a cool topic ....
ChrisViperM
Active Member
According to everydays logic, with everything "a little bit bigger"...and I am on the save side. That might be true on some - or most - occasions in life, it certainly is NOT true in electricity and elektronics. If you could not figure out from the links I gave in my previous post, I'll try it in a very simple way: If you mainly drive a car on small country roads or in the city, you will be fine. ..no overheating, good fuel consumption. This is called "efficient" . If you want to keep up with the Porsche in front of you with the same little car on a highway without speed limit, it won't take long and your car will make "poeeefff"...gone up in smoke. This is called "UN-efficient".....If you take a big strong car going on a highway 160 km/h is in terms of the engine layout, gearbox ect. and fuel consumption, "efficient". With the same big car going in city traffic in summer will make the big car overheat...it cannot work in it's efficient range,...lots of gear changes and only using very little of the possible engine power will push fuel consumption up and generate heat in the overall system..so it's unefficient.
There is only ONE bullet proof way to make your copter run cool, power-efficient and RELIABLE...that is choosing the components - motor, esc, LiPo, propeller - as close as you can - with app. 25% reserve - to their peak efficency. Everything smaller and everything bigger is contra productive. Fact is: Motor or/and Esc too small = lot's of heat and "poeeefff"....Motor and Esc too big = copter is very difficult to handle....Esc too big = creating heat due to it's internal structure = unefficient.
It took me a long time to understand all this electronic stuff in RC, but there is an even simpler way...try it out. Invest the time and try all possible combinations and measure the results. But for the theory, try to find out what the FET's are doing when they are "underused"....
Chris
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Benjamin Rowland
Member
I should change the title to THREE clients now. People want me to fly their Epic. I've got to find some motors that are appropriate for the job. Recommendations?
DucktileMedia
Drone Enthusiast
maybe buy that guys trex 700 gasser on the forum here. he only wanted $900 for it. You're flying in manual mode anyways, there wont be much difference. And you'll have auto rotation and superior wind/high speed performance.
Other than that you are looking at the next step up in motors, either Axi 4120's or 2826's. If i did it i would get the 2826/12's. Your 40 amp plushes might handle those as well. i think they are 37amp motors.
Other than that you are looking at the next step up in motors, either Axi 4120's or 2826's. If i did it i would get the 2826/12's. Your 40 amp plushes might handle those as well. i think they are 37amp motors.
Benjamin Rowland
Member
The 2826 motors look good.
These have also been suggested:
http://www.rctigermotor.com/show.php?contentid=144
Thoughts?
DucktileMedia
Drone Enthusiast
It's a $40-50k camera, what's another $600 in motors gonna matter to get the best. Any and all costs to avoid putting MSG in your heli should be taken to have that extra safeguard against failure. Although i am sure those tigers are mostly good, I did get a bad motor twice now from them. Once replaced they were perfectly fine but I think it is a peace of mind thing to have the best. You will probably be nervous enough flying that kind of dough.
ChrisViperM
Active Member
Should you consider a Heli - maybe now or in future - have a look at this:
http://www.helicommand.com/index.php?option=com_content&view=article&id=53&Itemid=60&lang=en
http://www.helicommand.com/index.php?option=com_content&view=article&id=48&Itemid=55&lang=en
The Heli Command from Robbe is used by professionals all over the world for filming with Singlerotor Helicopters. Maybe you know, but flying with Single Rotor is like putting one glass ball on top of another one, and trying not to let it fall down....a complete different game. Once I started, it took me 4 month to keep that damn thing hoovering on one spot and make very basic maneuvers. If you have a very experienced heli pilot in your neighborhood and use the Heli Command and don't have to fly yourself and can concentrate on the filming, you could get into it pretty fast....if you have to do everything on your own...forget it in the very short term.
...unless you can do it like her:
http://www.youtube.com/watch?v=xooni5CM_DQ&feature=related
Benjamin Rowland
Member
Does Axi have that reputation for being the best?
ChrisViperM
Active Member
They are developed AND manufactured in Europe/Check Republic and have a very high quality level. You won't find too many complaints about them...and their customer service is pretty good. Me and some friends use them in all sorts of applicatons - Multicopter - Fixed Wing - Single Rotor and never had a problem with them. They work best - at least for us - together with the JETI ADVANCE PRO ESC's which you also find information about on their website. Advantage of using Axi + Jeti...it is top products and you only talk to one guy in case something is not working.
http://www.modelmotors.cz/index.php?page=1
R_Lefebvre
Arducopter Developer
This is all completely untrue. I've heard the idea about using too large of an ESC causing heating, but never seen any well described reason. I am currently using a 100A ESC on a 600 Heli, but in fact it only averages about 25 amps. It's totally cool when it comes down. Unfortunately in the hobby industry, these myths take on a life of their own and are hard to stop. Most people don't even realize that the majority of the heat in an ESC actually comes from the BEC circuit. I can see this on my quad, since only one of the ESC's (the one I'm using BEC voltage from) gets warm at all.
I think this idea used to be true maybe back in the day with brushed motor ESC's which switched power at high speed to throttle the motor. The FETs have low on-resistance, and the bulk of the heat actually comes during the switching phase. They have a small, but defined switching time, during which they actually have significant internal resistance. This is when the heat is created. If you have a large ESC that has to swtich on/off a lot to throttle the power, it will make more heat than an ESC which is full-on.
But I really don't see how it's true in modern BLDC ESC's which are always switching for commutation anyway, and also use modern, ultra-low resistance and ultra fast switching FET's.
Also, your analogy to cars is completely untrue. You can take a little modern car and drive it all day long with the pedal on the floor without having any problem at all. And you can take a big modern car, and stick it in the city and idle around all day without over heating. What you say used to be true, but modern engineering has solved all these problems. Now, inefficient? Yes, but it won't overheat and go "poeeefff".
Now, as to the comparison of using a Heli to do this vs. a Multicopter, I have flown both big and small helis with the Arducopter System, as well as a quad with Arducopter. I really wouldn't say that there is much difference at all. My flybarred 600 flies VERY easily with Arducopter. The quad by comparison is a bit easier, but that's probably only because my quad is underpowered, so all the controls are much softer. The same effect could probably be achieved by simply tuning the heli to be soft. My flybarless 450 is a different animal completely, but that's not what we're talking about here. I think the experience of flying a large heli, and a large multi are pretty similar with a good flight controller. The only difference as I see it is that a helicopter has HUGE mechanical complexity, so I'm actually moving in the other direction: from helis to multis. It can be very tricky to get a flight controller to work well on a helicopter because of vibration.
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