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Old Sep 06, 2012, 11:16 PM
Head in the clouds
slothy89's Avatar
Australia, VIC, Sebastopol
Joined Apr 2012
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Search this thread for the previous discussion on the use of diodes to reduce voltage. Short answer is that it's not a good idea. The heat generated would surely fry the diode after a short time. Possibly even catch fire.
There is also a link to a 7.4v UBEC which is rated at 5A from HobbyKing.

Use the search!
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Old Sep 07, 2012, 01:56 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
Good tip Slothy - here's the link.
http://www.hobbyking.com/hobbyking/s...ly_6_23v_.html

(but the long answer is the right one on the diode question. A 5A diode will run all day with no probs at that current: PC PSU has similar. No fire risk!)
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Old Sep 07, 2012, 02:18 AM
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Malaysia, Federal Territory of Kuala Lumpur, Kuala Lumpur
Joined Jul 2012
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mmmm... don't know about you guys but I kinda interested to get a d700 3d... the price here is around MYR680 which is equivalent tu USD218...
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Old Sep 07, 2012, 02:48 AM
Fly Fast, Fly Hard, Fly Fun
rexless's Avatar
Canada, BC
Joined Apr 2012
1,527 Posts
Quote:
Originally Posted by slothy89 View Post
Search this thread for the previous discussion on the use of diodes to reduce voltage. Short answer is that it's not a good idea. The heat generated would surely fry the diode after a short time. Possibly even catch fire.
There is also a link to a 7.4v UBEC which is rated at 5A from HobbyKing.
Use the search!
Damn man... I was searching. When you don't know all the terms and get all sorts of snips of conversations it can be frustrating. I appreciate the tip about the 7.4v UBEC. I didn't think to search for that specifically.

Quote:
Originally Posted by OldOz View Post
Good tip Slothy - here's the link.
http://www.hobbyking.com/hobbyking/s...ly_6_23v_.html

(but the long answer is the right one on the diode question. A 5A diode will run all day with no probs at that current: PC PSU has similar. No fire risk!)
Excellent thanks! I'll go see if I can find the diode talk and learn a bit more. I had read some stuff on it and was convinced it was not an option.

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Originally Posted by OldOz View Post
Rexless -
A good idea, but unfortunately the output voltage seems to be 6V max (not enough for tail rotor). A simple adjustable regulator would give the exact voltage, but isn't as efficient. A switching adjustable regulator would require a little familiarity with electronics. The diodes would definitely work, but suffer a disproportionate voltage drop as the 11.1V LiPo fades in use.
Got to be an ideal solution out there!

A simple regulator
http://www.ti.com/lit/ds/symlink/lm138.pdf

A switching adjustable regulator, 5A
http://www.alldatasheet.com/datashee...2678T-ADJ.html
Thanks for the info. That LM138 looks amazing. I can solder OK in most hacks but have very little experience dealing with more than a few LED circuits or wiring fixes. I havent read the second datasheet yet. Do you do electronics?

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Originally Posted by juang1430 View Post
Today my f45 main motor has died on its 63rd flight. But I am very pleased with this fantastic bird as I've never replaced anything other than a dead tail motor so far. Thus today after work, I'm planning to drop by at the LHS where I had bought the f45 a couple of months back (won't be too sure if they can remember me well..). They got lots of f45 parts there, and maybe this time I'll buy a complete bnf unit to fulfill my spare part needs..
63 flights sounds great! You're lucky to have a shop close by. I rely on international shipments for parts and it's often the part I don't have yet that failed. I haven't seen any BNF Version myself but if you do find one that sounds great. Someday I think another local will buy one so we can share parts stock.
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Old Sep 07, 2012, 03:08 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
Rexless
-
Only a newbie here in heli world, learned a lot from you guys. (But 40+ years in industrial, commercial, and geophysical electronic design). I'm old!
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Old Sep 07, 2012, 03:19 AM
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Malaysia, Federal Territory of Kuala Lumpur, Kuala Lumpur
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Originally Posted by OldOz View Post
Rexless
-
Only a newbie here in heli world, learned a lot from you guys. (But 40+ years in industrial, commercial, and geophysical electronic design). I'm old!
Hi John,

most of your sharing here teach me a lot, thanks to that.

For your info, a d700 3d is the latest (2012) 6ch heli by ESKY..

Its kinda resembles an f45 a bit, as far as my eyes can see.

you can google esky d700 3d for a better picture

cheers!
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Old Sep 07, 2012, 03:25 AM
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Malaysia, Federal Territory of Kuala Lumpur, Kuala Lumpur
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Originally Posted by rexless View Post
Damn man... I was searching. When you don't know all the terms and get all sorts of snips of conversations it can be frustrating. I appreciate the tip about the 7.4v UBEC. I didn't think to search for that specifically.


Excellent thanks! I'll go see if I can find the diode talk and learn a bit more. I had read some stuff on it and was convinced it was not an option.


Thanks for the info. That LM138 looks amazing. I can solder OK in most hacks but have very little experience dealing with more than a few LED circuits or wiring fixes. I havent read the second datasheet yet. Do you do electronics?



63 flights sounds great! You're lucky to have a shop close by. I rely on international shipments for parts and it's often the part I don't have yet that failed. I haven't seen any BNF Version myself but if you do find one that sounds great. Someday I think another local will buy one so we can share parts stock.
Hi rexless;

sounds great! i'll be looking forward to realize it for sure....
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Old Sep 07, 2012, 03:30 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
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Juang, You're leaving us for CP!

But got to say, can see how you'd be tempted. 450 size, 6ch, and BL from the get go, you'll be in a different world for sure.
Only thing I know about THAT world is that repairs seem to be very expensive. But - if you vanish from this thread - PM me on how it goes

Best
John
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Old Sep 07, 2012, 04:46 AM
when is the wind stopping??
markkona's Avatar
Malta, Marsaskala
Joined Apr 2011
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http://www.xheli.com/eskyheli-004010-d700-3g-bnf.html


mmmm they have the fbl version too quite tempting at 238USD
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Old Sep 07, 2012, 04:49 AM
Registered User
Malaysia, Federal Territory of Kuala Lumpur, Kuala Lumpur
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Originally Posted by OldOz View Post
Juang, You're leaving us for CP!

But got to say, can see how you'd be tempted. 450 size, 6ch, and BL from the get go, you'll be in a different world for sure.
Only thing I know about THAT world is that repairs seem to be very expensive. But - if you vanish from this thread - PM me on how it goes

Best
John
Hi John;

it has 2 version; flybar and flybarless.. I think i'll stick to flybar version..
it'll remind me of my 2 1/2 cents crazy idea (not so long ago) of an f45 with a 6ch system..lol..
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Old Sep 07, 2012, 06:04 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
Juang -
I can see you're about to take the plunge - go for it, the youtube vids look very convincing!
With my interest in AP, I'm sort of thinking this way -
http://www.ebay.com.au/itm/Rc-Hubsan...461193736#shId
Think the FPV on the TX would be awesome: but also think you might lose sight of the heli (in the air) while admiring it . But very tempting...
Cheers
John
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Old Sep 07, 2012, 06:07 AM
Tinkerer of makeshift failures
Darsh's Avatar
Joined Jun 2012
325 Posts
I see there is also the D550 which is the sized of a F45 ( the D700 is a 450 size )...
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Old Sep 07, 2012, 07:52 AM
Brent 黑雁
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Canada, AB, Ponoka
Joined Jan 2012
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Quote:
Originally Posted by juang1430 View Post
Hi John,

most of your sharing here teach me a lot, thanks to that.

For your info, a d700 3d is the latest (2012) 6ch heli by ESKY..

Its kinda resembles an f45 a bit, as far as my eyes can see.

you can google esky d700 3d for a better picture

cheers!
If you go for it, I would suggest the flybarless. The flybar version will be much harder to fly, especially when your learning. Hopefully they have improved their TX. The advantage of a flybarless is they all have a 3 axis gyro which stabilizes the heli into a chosen orientation. The flybar system is slower to react causing a tendency to over control which is bad when your are just learning. I have a 450 with flybar and it requires much more attention than my 400 flybarless.

I just order a Walkera Master CP yesterday. It is bigger than my V120 and smaller than my V400. It has a 6 axis gyro and I wanted to see how that works.
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Old Sep 07, 2012, 08:37 AM
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Malaysia, Federal Territory of Kuala Lumpur, Kuala Lumpur
Joined Jul 2012
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Originally Posted by BThirsk View Post
If you go for it, I would suggest the flybarless. The flybar version will be much harder to fly, especially when your learning. Hopefully they have improved their TX. The advantage of a flybarless is they all have a 3 axis gyro which stabilizes the heli into a chosen orientation. The flybar system is slower to react causing a tendency to over control which is bad when your are just learning. I have a 450 with flybar and it requires much more attention than my 400 flybarless.

I just order a Walkera Master CP yesterday. It is bigger than my V120 and smaller than my V400. It has a 6 axis gyro and I wanted to see how that works.
6 axis gyro should be more stable and easy to fly compared to 3 axis gyro..
As for me, right now I would rather get a flybar version due to budget restriction.....
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Old Sep 07, 2012, 08:58 AM
Brent 黑雁
BThirsk's Avatar
Canada, AB, Ponoka
Joined Jan 2012
1,772 Posts
Quote:
Originally Posted by slothy89 View Post
Search this thread for the previous discussion on the use of diodes to reduce voltage. Short answer is that it's not a good idea. The heat generated would surely fry the diode after a short time. Possibly even catch fire.
There is also a link to a 7.4v UBEC which is rated at 5A from HobbyKing.

Use the search!
The best reason I can give for using 2 batteries is no noticeable power drop.
If you only use one 11.1 volt battery, you can only easily fit in the 1500mah. You are right about nothing larger fitting.
If you use a UBEC, the pcb and tail motor are dependent on the main battery for power. When the main motor is also drawing power, the available amperage and voltage are interdependent on this available power source.
The setup I ended up with uses a separate 7.4 volt battery to run the PCB/tail motor. The 7.4 volt battery never gets below 7.8 volts after 8 minutes of flying so the tail motor and servos are never starved for power. The main 11.1 volt battery also only gets to about 11.5 to 11.6 Volts over 8 minutes and because the main motor is the only thing drawing of it, the main motor is never starved for power.
Using the 2 batteries keeps the CG almost perfect. I don't like shifting weight to achieve different flight tendencies. If the heli does not handle as I think it should, then something is not right.
In the case of the F45, we have enough swash movement as can be demonstrated by giving a quick flick of the cyclics. The bird jumps and then settles down into a stable position. This is not a lack of swash plate movement.
It is the flybar controlling the cyclic blade pitch. Someone reduced the weight and found more response. I am just waiting for one more piece so I can finish modifying the flybar to use paddles and adjustable weights to fine tune the flybar.
My 2 cents worth.
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