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Scorpion Power Scorpion Power
HelicopterFlybarless Rotor Head SystemsOther › Futaba's New GY750 system at tower with price.
02-17-2011 08:38 AM  6 years agoPost 81
MrMel

rrProfessor

Gotland

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While the article was an intersting point of view the un-named author clearly has lost sight of a few facts. First, 10 high torque servos are not going to pull 20 to 30 amps as he starts off his scare campaign. As we've seen in our own tests, and from what Matt shared above, a 5 servo helicopter is pulling at most 4A total. Even if we eliminate the throttle servo as a cause of major drain, we're only talking 1A peaks per servo, with an average load of 0.25A per. Doing the math here that would mean an average load of 2.5A with peaks of 10A. Quite different from the quoted 20-30A load. Put another way, that 20A load would obliterate a 4000mah pack in 10 minutes. How many big scale plankers have you seen putting in a full charge after each flight?
I have logged several flights with peaks 12-15A with just 3 x JR8717.
Stall current on a JR8717 is over 3A each, but start current is very high too, perhaps even higher when you start them under load.
These are short peaks, probably wont burn a connector, but you do get very high voltage loss = less performance on the servos.
(tested this on a Jive with 1 vs 2 cables, was 0.7v difference between running it, measured with a scope at the servos and that was without much load)

Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more

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02-17-2011 01:59 PM  6 years agoPost 82
mmc205

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PA - USA

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wow, very cool info mr. mel!

***Logo 600 vbar***Henseleit TDR vbar***

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02-17-2011 03:21 PM  6 years agoPost 83
basmntdweller

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Indianapolis IN

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I have no doubt that my Eagletree's data capture rate likely missed noticeably higher current peaks and something as simple as a blade change could drastically load up the servos more. I flew with stock Align 690's yesterday. FBL blades with the CG forward would definitely draw more current. That change alone could be enough to go from the 3.81 amps I recorded to the 12-15 that MrMel has seen. I don't have any FBL blades yet so I can't make that comparison. I wish I had a set to test though!

As far as the article on S-bus, I think there is a degree of planning and truth to Futabas approach. I have always preferred Futaba servos but I now fly Spektrum and JR. If Futaba goes S-bus only servos, I'll be looking at different servos to buy!

Matt


Stupid people have no idea how stupid they are!!!

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02-17-2011 03:25 PM  6 years agoPost 84
MrMel

rrProfessor

Gotland

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Important to know also that Futaba BLS servos have much lower current draw than JR/Align/Savox. (very much lower, especially in FBL solutions)

Anyway, Short cables and if you want a Y cable to put in some extra power in parallel will keep the voltage up, so even if a system just have one single connector, there is always a solution, even one that wont make a big hole in the wallet.

(Same issue on Mini Vbar in some hookups, just run a Y cable off one of the servos to get the extra power in there, no biggie)

Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more

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02-17-2011 04:01 PM  6 years agoPost 85
Felt

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Acworth, Ga

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The solution is called a Reactor X..

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02-17-2011 04:02 PM  6 years agoPost 86
nickmcdonald

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new lenox, il

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Mr. Mel, would you care to share what your total mah draw is per flight. While I haven't had a lot of experience with 8717's, I do know Futaba's BLS servos as well as Align's. In my now retired and sold flybared 90 I ran all Futaba BLS-451's with a BLS-251 on the tail. Draw per 7:30 minute flight was in the 250-350mah range. On my current T700N FBL running Align cyclic's and a BLS-251 on the tail, I am in the 300-450mah range per 7 minute flight.

While logically I could agree that the Align servos should draw more power (Torque and Speed specs "If accurate", the data I have collected does not support a large difference.

I also failed to mention, I do agree with the fact that there should be a heavy duty power bus in the S-Bus system. While I still don't see giant scale planes pulling down 30A, anything above 3A-5A should be fed by multiple heavy gauge leads. To me this single power lead issue is no different than why Futaba insists on making servos that follow the same old power requirements instead of something that will run off straight 2S lipos. I think we would all stop complaining about amp draw then. Take that 15W power draw onto a high voltage system and instead of a 3A draw we would be down to 1.8A.

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02-17-2011 04:13 PM  6 years agoPost 87
MrMel

rrProfessor

Gotland

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I've given up on nitros and RX packs a while back, as well JR8717 servos.
But recently I used a LiFe RX pack for my VBar governor testing on a L600 with 8717, and draw for that was about 280mah for a 4:30 flight.
That's on a 600.

Do note that current draw on servos go up with voltage as speed and torque of the servo increase.

Gone fishing..or hunting..or something
My site: http://heli.dacsa.net - VBar videos and more

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02-17-2011 04:54 PM  6 years agoPost 88
nickmcdonald

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new lenox, il

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I'm almost of the same mind, got a 700E on the way

While I agree a Logo 600 is only a 50, a Logo is far from being a slouch. And given the power systems I have seen on most Logo 600E's, I would venture to say the cyclic power needed for your machine and mine is closer than you think.

Your setup comes out to an average current drain of 3.7A. Given a 10 minute flight you would pull ~620mah not 4000mah as the article in question suggests.

Also note that I am speaking of a servo designed for a high voltage system. True the same servo plugged into different setups will draw more on the higher voltage one. But given a servo built to produce the same torque and speed on an HV system, it will draw less amps.

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02-17-2011 04:56 PM  6 years agoPost 89
rexxigpilot

rrProfessor

Florida

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The current draw data that Fredrik got versus what Matt got is easily explained by the different recording equipment. The scope has the ability to show instantaneous transients whereas the Eagle Tree cannot. Whether transients should be considered peak draw is debatable.

In the real world, transients or spikes are typically irrelevant. Some of you would be amazed at the voltage transients from common household power. Municipal water supply pipes that are designed for 150 psi often see pressure transients from water hammer that exceed 1000 psi. The point is that duration must be considered before we can assess the impact of a transient or peak spike.

Nick, your third point was right on point!

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02-17-2011 06:47 PM  6 years agoPost 90
basmntdweller

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Indianapolis IN

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Do note that current draw on servos go up with voltage as speed and torque of the servo increase.
Generally speaking this is true, but the load has to go up for the torque to increase. If the torque stays the same(same load on the servo) then the current will only rise the amount it takes for the servo to move faster. Essentially seeing a shorter duration current spike.
Whether transients should be considered peak draw is debatable.
FWIW, non of my current spikes over 3 amps lasted more than half a second.
I remember a few months back someone started a thread about e-heli power claims being given in those same instantaneous spikes. It may have been RedZ06 or whatever his nick is. I didn't save my recorder file or I would try to find the highest/longest sustained load. My guess is it would be under 2.5 amps and not last more than 2 seconds.

Matt


Stupid people have no idea how stupid they are!!!

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02-17-2011 06:50 PM  6 years agoPost 91
bxc53

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Directly over the​center of the Earth​( 98223)

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Question for the Futaba team guys

What is needed to connect the GY 750 to a S-bus RX?

I'm guessing it's a double male extension like the GY-520 uses?

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02-17-2011 07:32 PM  6 years agoPost 92
willie evans

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Alberta, Canada

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over one year old.

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02-17-2011 08:25 PM  6 years agoPost 93
kcordell

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O Fallon, MO

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Yes, the only connection to the CGY-750 from the RX is one male/male cable. On mine, the only connection to the R6108SB is the S.Bus cable, ESC, Battery.
Everything else is on the CGY-750. Also, as with the GY-701 and the GY-520, if you use an S.Bus RX, you only need one connection for the gyro. The gain is done automatically thru the radio.

Team Futaba, Team Synergy/Rail, Team Scorpion, Team Castle Creations, YS Engines, VelTye

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02-18-2011 02:03 AM  6 years agoPost 94
maxw

rrApprentice

Ipswich Suffolk​United Kingdom

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Hi
on that note any one know if the CGY-750 has a S.Bus in and out?
was just thinking how just the one cable runs from the receiver to the CGY-750 unit yet all the cables come out again ie throttle ali ele pitch tail servo etc if there was a S.Bus out then you was using S.Bus servo or S.Bus Decoder all you would need is a S.Bus hub then link all the rest of the servos into that how neat would that be? one from receiver to CGY-750 one cable out sweet not only that you could conect another battery into the link if needed
hope this all makes sence

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02-18-2011 12:17 PM  6 years agoPost 95
kcordell

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O Fallon, MO

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On a heli, why would you want to include the S.Bus hub? With it as the way it stands, depending on CGY-750 placement, you may only need one short servo extension, and if you wanted to place the CGY-750 farther away from the S.Bus RX, you can get a longer male/male cord (there is more than one length available) as is already sold by Futaba. The hub system is really for the giant scale/jet guys who are running long servo extensions and multiple servos on control surfaces.

Team Futaba, Team Synergy/Rail, Team Scorpion, Team Castle Creations, YS Engines, VelTye

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02-18-2011 01:32 PM  6 years agoPost 96
Dr.Ben

rrMaster

Richmond, VA, USA

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Kevin,

I think his context would be if there were other non-core control servos in the model.

Neil,

The nature of this flight control system, like others, is that one way or the other it has its hand in AIL, ELE, RUD, PIT, THROTTLE, GYRO GAIN, GOVERNOR SPEED, AND GOVERNOR ON/OFF.....IOW, most of the controls in the model. If you have any other servos like retracts, etc, then the 6203SB and certainly the 8CH SB have PWM slots for those functions. I understand the gist of your idea, but in a heli, it's more unusual to get into the plank wiring nightmare with multiple banks of servo at a distance from the receiver. Thus it's more difficult to justify the space on the board for an S.Bus out port with relatively little potential application in a helicopter.

I hope that makes some sense to you.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

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02-19-2011 12:01 AM  6 years agoPost 97
maxw

rrApprentice

Ipswich Suffolk​United Kingdom

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Hi Ben

it was just a wonder question thats all wasnt wanting to do this but do understand what you was both saying about more for large planks etc
and just wondering as there is heli S.Bus servos out there

another quick question what type of volt reg would be good to use on the CGY750? as alot out there ie scot gray perfect reg etc have cables for the ccpm channels

and the fromeco reg im using at the mo runs power into the rud and gain channel of the receiver

can i only use a reg that sits inline between the li po and receiver? or is there other ways to power this?

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02-19-2011 01:08 AM  6 years agoPost 98
bkervaski

rrElite Veteran

Birmingham, AL, USA

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You could use the Reactor X or Gryphon ... just run the servo output from the CGY750 to the reg, then from the reg to the servo's, this also has the nice side effect of powering your system without a wire to the RX. This is how I currently have my S.Bus VBar setup.

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02-19-2011 03:16 AM  6 years agoPost 99
kcordell

rrElite Veteran

O Fallon, MO

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I am running a Duralite 5.3 with HD switch on my CGY-750 with R6108SB receiver. No issues.

Team Futaba, Team Synergy/Rail, Team Scorpion, Team Castle Creations, YS Engines, VelTye

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02-21-2011 02:22 AM  6 years agoPost 100
panzlflyer

rrApprentice

Goldsboro,NC,USA

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While the article was an intersting point of view the un-named author clearly has lost sight of a few facts. First, 10 high torque servos are not going to pull 20 to 30 amps as he starts off his scare campaign. As we've seen in our own tests, and from what Matt shared above, a 5 servo helicopter is pulling at most 4A total. Even if we eliminate the throttle servo as a cause of major drain, we're only talking 1A peaks per servo, with an average load of 0.25A per. Doing the math here that would mean an average load of 2.5A with peaks of 10A. Quite different from the quoted 20-30A load. Put another way, that 20A load would obliterate a 4000mah pack in 10 minutes. How many big scale plankers have you seen putting in a full charge after each flight
Not to beat a dead horse but all of my 35% plankers easily pulled 11 amps in a snap roll, however they used 350-400 miliamps per 10 minute flight.
measured in flight multiple times on my own and others planes 35-40%
How much they consume doesnt tell how high the current goes for a split second.
One servo connector simply isnt enough and Ive seen factory pilots bite the dust because their setup guy didnt factor in the load, one whose name begins with Q even wrote a short article about it as he relied on a single Duralite regultor.
I dont think our helis will pull 20amps, but one 3 amp connector is doing a lot of duty, the 2.5amps with 10amps peak sounds pretty realistic.
Just because "factory" guys say it okay doesnt make it so, I seem to remember them declaring no problems with the 3g as well lol

T700,450Pro,Spirit Pro,Beast+, Qav 500,Futaba18SZ

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