HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old May 05, 2012, 04:03 PM
"I want more air time!"
Eternalflight's Avatar
Joined May 2008
1,167 Posts
Quote:
Originally Posted by NorCalMatCat View Post
You don't want the water too hot, you don't want to melt the foam :P
I started this morning with 120* tap water, running over the wing tip and it's starting to lay down. I kept the wood on there the hole time i was drowning the tip. The tip looked like a taco shell and thought I may snap it working it into a normal shape.

Quote:
Originally Posted by Maddmax View Post
I use a microdan 2535kv in my fpv plane and it flies really nice.
LOL! Thanks, makin me feel better
Eternalflight is offline Find More Posts by Eternalflight
RCG Plus Member
Sign up now
to remove ads between posts
Old May 05, 2012, 04:22 PM
Better then Sliced Bread!
NorCalMatCat's Avatar
United States, CA, Arcata
Joined Oct 2011
2,650 Posts
Quote:
Originally Posted by Eternalflight View Post
I started this morning with 120* tap water, running over the wing tip and it's starting to lay down. I kept the wood on there the hole time i was drowning the tip. The tip looked like a taco shell and thought I may snap it working it into a normal shape.


LOL! Thanks, makin me feel better
That right there looks about right.
NorCalMatCat is offline Find More Posts by NorCalMatCat
Reply With Quote
Old May 05, 2012, 05:31 PM
Why so serious?
2500GENE's Avatar
United States, FL, Cape Coral
Joined Dec 2007
5,972 Posts
Quote:
Originally Posted by jj604 View Post
Interestingly I tried a bunch of cheap 20-25 Amp ESCs I had with inbuilt (presumably linear) BECs on the 4x 939MG servo load at rapid cycle and they all got hotter than a bunch of rednecks at a pole dance contest.

Two of the cheapy (RC Timer/Turnigy) 3A switching BECs shut down intermittently on the same test. You need to be careful trusting these things.
It might be worth noting most BECs are rated using around a 2 cell lipo. A 3 cell causes them to work harder and create a lot more heat. Dropping voltage to 5vdc is easier from 7.1-8.4 the from 11.1-12.6. This is for linear BECs.
Switching BECs work a bit harder also but not in the same way a linear does. A linear will convert the excess voltage to heat through a resistor while the switching BEC will switch rapidly between on and off to average 5vdc. The result is less heat generated from the switching BEC then the linear.

If you use a ESC with a linear BEC, make sure it gets good cooling.
Also remember as always, you get what you pay for.

Now, back to my pool.
2500GENE is offline Find More Posts by 2500GENE
Reply With Quote
Old May 05, 2012, 05:41 PM
Better then Sliced Bread!
NorCalMatCat's Avatar
United States, CA, Arcata
Joined Oct 2011
2,650 Posts
I have 2 different switching becs at the moment I use, I have a higher quality 5a in my plane, and a 3a one on my radio (to power radio + 1watt amp), and neither change temp in any fashion even if worked hard.
NorCalMatCat is offline Find More Posts by NorCalMatCat
Reply With Quote
Old May 05, 2012, 05:43 PM
'tis nothing
shunyata's Avatar
United States, CA, Napa
Joined Dec 2011
941 Posts
Quote:
Originally Posted by Maddmax View Post
I use a microdan 2535kv in my fpv plane and it flies really nice.
Is that motor more quiet than the stocker? The stock brushless was so noisy, that's why I went the other way, 1100Kv and an 8 inch prop. Anyway, is it a lot better?

My son told me this morning he didn't want to bother installing the same motor setup in the heavy Bixler (as I did with the other SS) as he has other plans for it when the Sky Walker is ready. I'm thinking he might want a higher Kv motor than stock since he wants to trim the wings and make it a go-fast silly flier. lol
shunyata is offline Find More Posts by shunyata
Reply With Quote
Old May 05, 2012, 07:55 PM
Soon to be CrashMasterPhil
Rochester MN
Joined Dec 2007
755 Posts
Any chance you tested the more popular MG90s, which HK USA and Hobbypartz sells?

http://www.hobbypartz.com/servo-mg90s.html

http://www.hobbyking.com/hobbyking/s...dProduct=23594

Quote:
Originally Posted by jj604 View Post
Prof's comment got me wondering what the current was in practice. Actually measuring servo current draw isn't as easy as you might think since you need to look at both the peak current (which might burn something out as an electric overload) and average current (which will heat everything up). Turns out max. current was almost the same as the average.

I popped 4 of the very popular HXT 900's on my servo tester and measured the current using a stable 5V 40A supply with a Dimension Engineering ServoSense Plus, after allowing for the current the servos tester uses. This is as close as I can get to a typical BEC situation and will allow the servos to draw their max current.

For four HXT900's (which is what I have in my Bixler) the results were:

Idle (not moving)
<0.1A total
Cycling (8 sec end to end)
0.5A total
Cycling (0.5 sec end to end)
1.8A total
Stalled
2.4A total

As people know, these servos work great in a Bixler. They are noisy and have a quoted Torque of 1.6kg-cm. They cost $2.69 - when they are in stock.


For four HobbyKing 939MG's (which is what are going into my EasyStar II today) the results were:

Idle (not moving)
<0.1A total
Cycling (8 sec end to end)
0.7A total
Cycling (0.5 sec end to end)
2.3A total
Almost stalled
3.2A total

I was unable to stall these ball bearing metal gear servos by hand. They are quiet and have a quoted torque of 2.5 kg-cm. They cost $4.37 - when they are in stock.

CONCLUSIONS

Using the "standard" 4x HXT900 servos in a Bixler, a 3A BEC is adequate, provided it is genuinely 3A. The additional Rx current is small.

Using the identically sized but costlier HK939MG's you will get a lot more torque (which is really unnecessary in a Bixler), significantly quieter and smoother, and what appears to be a stronger and better made servo mechanically. Theoretically a 3A BEC may be marginal under extreme conditions but as Prof says it isn't going to happen in practice. If you manage to get 4 fully stalled servos in flight you have bigger problems than your BEC rating.

Be aware however that just because an ESC says says 3A BEC on the label, doesn't mean it can actually supply that. Worth reading any reviews about it first.

Hope this is useful to someone.
divemasterphil is offline Find More Posts by divemasterphil
Reply With Quote
Old May 05, 2012, 11:07 PM
Registered User
AmishLou's Avatar
United States, VA, Quantico
Joined Mar 2012
33 Posts
Quote:
Originally Posted by taz101 View Post
Just to add to this:-
Always plug a spare opposing plug in to the one you are soldering, to absorb some heat from the plastic as to not melt it.
So if you are soldering a female plug, plug a spare male into it.

LURCH
Thanks for the tip. Sadly, I did not check the forum before I had my first soldering attempts this morning. Burned through 3 of my knock off XT60's when I would over heat the connector and the male end on the other side would dislodge and cool down after being pushed up at an angle that made it impossible to fit a female end onto it. Then I read about connecting a male and female before soldering one. It will help me in the future.
AmishLou is offline Find More Posts by AmishLou
Reply With Quote
Old May 05, 2012, 11:29 PM
Registered User
Prof100's Avatar
Canton, Michigan USA
Joined Jul 2007
16,648 Posts
Quote:
Originally Posted by divemasterphil View Post
Any chance you tested the more popular MG90s, which HK USA and Hobbypartz sells?

http://www.hobbypartz.com/servo-mg90s.html

http://www.hobbyking.com/hobbyking/s...dProduct=23594
The HXT900s are the most popular.
Prof100 is offline Find More Posts by Prof100
RCG Plus Member
Old May 06, 2012, 03:35 AM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
8,424 Posts
Quote:
Originally Posted by Prof100 View Post
The HXT900s are the most popular.
+1. By quite a margin I suspect. For me, I started using HK939mg servos (15 so far) and I love them. Powerful and quiet. But, about 62% more in cost. (2.69 vs 4.37) Unfortunately, at this moment, both are out of stock.
Next time I feel the need for servos, I am going to order the Corona 939mg servos. Any thoughts?
AJ
ajbaker is offline Find More Posts by ajbaker
Last edited by ajbaker; May 06, 2012 at 03:41 AM.
Reply With Quote
Old May 06, 2012, 07:12 AM
I need a bigger shed..
sammyc's Avatar
Australia, TAS, Launceston
Joined Nov 2011
1,498 Posts
Quote:
Originally Posted by ajbaker View Post
+1. By quite a margin I suspect. For me, I started using HK939mg servos (15 so far) and I love them. Powerful and quiet. But, about 62% more in cost. (2.69 vs 4.37) Unfortunately, at this moment, both are out of stock.
Next time I feel the need for servos, I am going to order the Corona 939mg servos. Any thoughts?
AJ
As far as I am aware, the HK939MG and Corona 939MG are the same. Although, you can get a digital version of the Corona 939MG. Check the hobbyking product code, the CS at start means analgue, DS means digital. Same goes for all the similar servo's (919, 929..)
Another good option would be the 929MG's, you are sacrificing torque for speed, but I spose the SS/bix doesn't need superfast servos. I have these coming for the cyclic on my 450 heli.
sammyc is offline Find More Posts by sammyc
Reply With Quote
Old May 06, 2012, 11:34 AM
Soon to be CrashMasterPhil
Rochester MN
Joined Dec 2007
755 Posts
Sorry, I was referring to $5 Metal Gear Servo's.

Quote:
Originally Posted by Prof100 View Post
The HXT900s are the most popular.
divemasterphil is offline Find More Posts by divemasterphil
Reply With Quote
Old May 06, 2012, 12:03 PM
Registered User
CPMBOY's Avatar
Malaysia, Sabah, Kuala Penyu
Joined Aug 2011
727 Posts
prep & ready 4 2nd flight

........wish me again....good flying!!!....and a camera buddy
CPMBOY is offline Find More Posts by CPMBOY
Reply With Quote
Old May 06, 2012, 02:04 PM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
8,424 Posts
Quote:
Originally Posted by CPMBOY View Post
........wish me again....good flying!!!....and a camera buddy
You want to talk to 2500GENE about those "a gain"'s. He has several extras to share - no need to "wish me again" when he has so much extra.
I am looking forward to your videos..
AJ
ajbaker is offline Find More Posts by ajbaker
Reply With Quote
Old May 06, 2012, 02:18 PM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
8,424 Posts
Page #1 maintenance & Help needed

All the links on Posts 2 & 3 are fixed. If anyone can find me some links to the 2835-2200Kv motor, I would appreciate it. I will post them on Page #1 with credit given to you for finding it. It appears that HK has quit carrying that motor. THIS is the only one that I have found. TIA.
AJ
ajbaker is offline Find More Posts by ajbaker
Reply With Quote
Old May 06, 2012, 04:40 PM
'tis nothing
shunyata's Avatar
United States, CA, Napa
Joined Dec 2011
941 Posts
aj, is this what you're looking for ?

http://www.advantagehobby.com/39424/...mpaign=product

BTW, thanks for doing such a great job maintaining this thread. One of the best on RC Groups!
shunyata is offline Find More Posts by shunyata
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale Cyber Sky Parachute (Sky Surfer) shv2sail Aircraft - Electric - Airplanes (FS/W) 6 May 28, 2013 03:14 AM
Discussion Sky Surfer nickwayne11c Electric Plane Talk 15 Nov 18, 2011 03:36 PM
Discussion Banana Hobby Sky Surfer Problems cavy92 Electric Plane Talk 56 Nov 02, 2010 03:49 AM
Question Sky Surfer LiPo mod, help... Freight Dog Power Systems 0 Aug 17, 2006 02:45 PM
Swashplate Assembly with Center Ball; is this the swash with ball mod i want? tekforce Micro Helis 4 Feb 08, 2004 06:28 PM