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Old Aug 21, 2011, 11:48 AM
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Sverige
Joined Aug 2011
2 Posts
Hello BG!

I never thought of reading cell per cell through white connector. I just tried this and when reading each cell they all delivered 3.3volt. So now i know they all seem to work, great, thank you!

The 2.99 volt reading is after ive connected the ESC to acc and reading from the connector that goes from ESC to throttle 3-pin on receiver. I assume this connector powers both receiver and all servos, or am i missing something. Should there be a connector also to 'B. Power/Frequency bind' on the receiver?

Why i got hung up on this is the page in manual that says operating voltage is 4.8v-5.2v, and right now, about half loaded acc it is getting 2.8volt.

Again thanks for the help
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Old Aug 21, 2011, 02:37 PM
Still a mile high when I land
MonsterBFC's Avatar
United States, CO, Arvada
Joined Mar 2011
104 Posts
Had a flap servo fail today on approach and sent the plane over right. I corrected it with ailerons and punched the throttle to get altitude but not in time not to catch a wing tip and sent the plane into a nasty wingtip spin across the field. Hit the nose so hard the motor came out of the fuse. Camera went flying, bent the spar into a smile, broke both wing mounts, broke the right wing tip off, broke the right aileron clean off, front of canopy broken off. I was running a 4S 3300 and the added weight helped smash things up real nice. I already have a second plane on order that I intended to use for FPV. I guess this one won't be used for road trips now. The servo that failed does nothing but buzz. I'll be changing out all servos. Who makes a good digital metal gear servo I could use?
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Old Aug 21, 2011, 03:17 PM
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BG Bengtsson's Avatar
Sweden
Joined Jul 2010
185 Posts
Hi Guys Sorry MonsterBFC...
Sorvo error seems to epidemic! Or maybe now at end of summer and a little harder flying?
Servo recomendations? anyone?

Regarding ESC volatage: Your right 4.8-5.2V is normal. Disconnect all servo. Measure Rx voltage. If ok, connect one at a time and see if any will consume too much current. If you have a dmm with Amp (10A without fuse) connect in series with ESC. Normally you shall be able to load at least 2-3A (good 4-6A!). I did connect a big 2500uF/10V Electrolytic capacitor on the "batt" connector on the Rx to help stabilize the load. I do not understand why there is no separate supply to the Rx itself... But that is another improvement to do one day...
/BG
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Old Aug 21, 2011, 05:01 PM
Still a mile high when I land
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United States, CO, Arvada
Joined Mar 2011
104 Posts
Has anyone ever seen this model? I have been looking everywhere for a glider with the same type specs as the 2500 only not in foam and I found this one. It doesn't have the same tail so it wouldn't be quite as stable, but I like the wing loading and materials. Thoughts anyone?
http://www.hobby-paradise.com/en/pro...ct_detail.html
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Old Aug 22, 2011, 05:08 PM
killickb
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The Villages. Florida
Joined Jan 2005
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Monster BFC, I very much doubt that you can say that a cruciform tail is more or less "stable" than a T-tail. Stability/Performance is all about design and what do you know about that model -- very little from the marketing blurb --- you gotta find someone who has one! Note that it is also rather more expensive but from my experience with the 2500 could it perform any worse?

Sorry to hear of your "incident" but these threads are full of foamy factory supplied electronics failures, why would you or I assume we are going to beat the odds !! Suggest that JR or Hitec servos will provide as much MTBF as you will find $ for $.

Did you add film to the wings? I doubt that the adhesive strength of film will add much bending strength to the wing. When we did Zagi combat we added mucho strapping tape to the raw foam wing which seemed to help but it didn't do much for the aerodynamics of the wing! Suppose you could mill out the wing and add more carbon tube spars, shouldn't add too much weight if you are more interested in camera work than soaring performance, just don't try to simulate the guy using FPV when he lost half the wing !!
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Old Aug 23, 2011, 12:03 AM
Still a mile high when I land
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United States, CO, Arvada
Joined Mar 2011
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Quote:
Originally Posted by killickb View Post
Monster BFC, I very much doubt that you can say that a cruciform tail is more or less "stable" than a T-tail.You of all people should know a cruciform is a bad choice for a glider. There is turbulance from the wings and fuse flowing over it, and it's not going to be as acrobatic OR as stable as a T-tail on a glider especially at low speeds. I think a V-tail is the way to go on a glider, but I guess it all depends on how you're going to fly. They seem to use all three on them. Stability/Performance is all about design and what do you know about that model -- very little from the marketing blurb --- you gotta find someone who has one!One of the guys I work with has one. He bought it in NZ on vacation, and I saw it hanging in his garage. He told me the company went out of business, but I looked it up online and found it. He said it's a good glider and won't sell it. I have yet to see it fly in person. I did find a video online and it looks like it slices quite nicely. Note that it is also rather more expensive but from my experience with the 2500 could it perform any worse?I would be the first to say that the 2500 is far from being a performance glider. In fact I have never flown a foam plane before it. The airflow across that foam makes it fly like poop, not like the old days with silk and Dope.

Sorry to hear of your "incident" but these threads are full of foamy factory supplied electronics failures, why would you or I assume we are going to beat the odds !! Suggest that JR or Hitec servos will provide as much MTBF as you will find $ for $. Ya, you're right about that. I should have known better when a brand new ESC shows up dead. You're right about Hitec too. I have already faced the truth that I'm going to have to spend the money.I did manage to get it back to fly with about 1oz. of 30 min and some CA.

Did you add film to the wings?No, I didn't. Just brainstorming on how to make this bird stronger. I was looking at the tensile strength of econokote, but you make me wonder about the adhesive bond. If it's not a good bond, it would be just a waste of time and money. I doubt that the adhesive strength of film will add much bending strength to the wing. When we did Zagi combat we added mucho strapping tape to the raw foam wing which seemed to help but it didn't do much for the aerodynamics of the wing! Suppose you could mill out the wing and add more carbon tube spars,(very likely the best answer. Sometimes thinking too much overlooks the only solution) shouldn't add too much weight if you are more interested in camera work than soaring performance,You know what?, I want both, but I'm going to do it with two planes. I'm trying to get my son into RC to join me. He is scared to death of my 550E, so I thought this bird would make a good one for him to try. just don't try to simulate the guy using FPV when he lost half the wing !!
Ya, I saw that. I have a hard time thinking about packing a plane like that with all that equipment. I don't think I would be very comfortable even with tape all over it. Plus, then it would REALLY fly like poop.
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Old Aug 23, 2011, 12:18 AM
Still a mile high when I land
MonsterBFC's Avatar
United States, CO, Arvada
Joined Mar 2011
104 Posts
OK models Mace video

Here is a video of the plane I was talking about. I wonder if I could put a V-tail on it???
OK Models Pilot Mace (3 min 23 sec)
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Old Aug 23, 2011, 11:26 AM
insert witty phrase here
Joined Aug 2006
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So after some searching about my 3720-1 ArtTech motor i've seen that there is some speculation regarding it's Kv (RPM/volt) Rating. this post states a speculative 700kv.
Quote:
Originally Posted by wa6rxm View Post
RE: Pictures. ... The motor's number is an A3720. The ESC is a 60 amp. so I am assuming that the motor has a moderate kV rating - likely 700 kV, which is the same as the Art-Tech Corsair is supplied with...
I have also seen on a distributor's website that there is a 3720-1A TopBrand motor with a 850kv rating.

does anyone have a true number for this motor? or am i going to have to get in there and measure it myself?

thank you for your help,
Brian
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Old Aug 23, 2011, 12:51 PM
killickb
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The Villages. Florida
Joined Jan 2005
1,234 Posts
Doesn't look all that bad in the video and at least it has a sharp t.e on the wings. Is it still availble in the US? Will your friend let you have a turn on the sticks?? Can't agree re cruciform tails. Looks like the Mace has an all moving tailplane which is nice --- low drag. I flew many a competition with both cruciform and vee way back when the world was simpler!! Grand Esprit, Challenger, Bird of Time, Cumulus etc and any of them could win if things went right. One good reason for vee tail was that it didn't catch in the grass on landing. There is supposedly less drag (parasitic mainly) I suppose as there is less tail assembly surface area. Flew in scale with a Slingsby T-53 which had a swept forward wing and tee tail but it was, like the 2500, a lead sled.
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Old Aug 23, 2011, 01:03 PM
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BG Bengtsson's Avatar
Sweden
Joined Jul 2010
185 Posts
I did measure the original motor without propeller:
12.51V Max trottle: 7466rpm=> 596.8rpm/V
16.83V Max trottle: 9990rpm=> 593.5rpm/V
after 6month of flying...
/BG
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Old Aug 23, 2011, 10:56 PM
insert witty phrase here
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Quote:
Originally Posted by BG Bengtsson View Post
I did measure the original motor without propeller:
12.51V Max trottle: 7466rpm=> 596.8rpm/V
16.83V Max trottle: 9990rpm=> 593.5rpm/V
after 6month of flying...
/BG
Awesome BG,
That means that we're probably looking at a 37-20 600kv (Chinese claim) motor.

Cheers,
Brian
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Old Aug 24, 2011, 01:42 AM
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BG Bengtsson's Avatar
Sweden
Joined Jul 2010
185 Posts
I tink you shall not go for a too low Kv. The ESC transforms the power from the battery to the motor. The original motor is working but weak at 3S. I have no experience in choosing Kv but if I would buy and try I would go for a little higher. Maybe 800rpm/V...?
37-20? Does that mean 37mm in diamerer and 20 turns of cupper wire in the motor? That is an important factor coil turns, or what it is called in English. If we increas Kv to 800 That means 800/600*20=27 turns. That means much thinner Cu diameter and higher resistance... Maybe the 600kv is best anyway!...

Opsh I think I was to fast here! It is the opposite. Kv is rpm/V not V/rpm. That means that the turns goes down with higher Kv.
If 20turns gives 600Kv then 800Kv is 600/800*20=15 turns. And that is a lower resistance. Maybe I would try 800 anyway!...

Anyone else with experience?
No one here have turned the original motor down. We all fell happy with it.
/BG
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Last edited by BG Bengtsson; Aug 24, 2011 at 01:52 AM. Reason: thoughts about Kv versus turns
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Old Aug 24, 2011, 02:03 AM
gravity tester
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LaPine,OR Quarztsite AZ
Joined Nov 2008
706 Posts
Hi BG, well spoken....i have found the stock motor puts out plenty of power for near vertical climbs, outside loops, and positive rolls. a couple factors that could increase a little performance is higher C lipos, larger stiffer props....something to consider, when increasing the speed of this aircraft, higher loads are imposed on the servos, on the flaps, elevator, ailerons= servo failure....after i inserted a carbon fiber rod into the stock aluminum spar, i put my Diamond into a couple speed dives to check for wing flex....the Diamond is limited in it's ability to achieve a high speed because of it's inherent design and limitations....i enjoy it for what it is, a fun, slightly aerobatic, stand-off scale looking electric sailplane that cost very little and is made of foam. Hey BG, we're heading to the lake for about a week!
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Old Aug 24, 2011, 02:08 AM
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BG Bengtsson's Avatar
Sweden
Joined Jul 2010
185 Posts
Hi Phil! Nice to here from you. I have had a very long vacation now! 7 weeks. But back to work on monday... My Diamond is still flying but need some hours to refresh. The wing is not tight anymore to the fuse. I am thinking of implanting plywood in fuse fore the two pins, to stiffen up...

But hey! It must be midnight in Oregon?!??
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Old Aug 24, 2011, 02:24 AM
gravity tester
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LaPine,OR Quarztsite AZ
Joined Nov 2008
706 Posts
Yes, it is after midnight, linda and i have been busy packing up our RV. i'm sure you enjoyed your vacation, because i am aware of how hard you work. i'm glad your Diamond is "loosening-up", as that means you're flying it!...let us know what you do for your wings...i have been enjoying my helicopter, and linda and i have a couple RC sailboats....and last weekend i won a 4WD modified race
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