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Old Jan 05, 2008, 09:10 AM
Registered User
Germany
Joined Jan 2007
72 Posts
Quote:
Originally Posted by Rare Bear
Wolf - that battery looks good, but I agree - kind of hard to settle on a no name brand. So, as for a 4S setup, what do you think flight times would be? I could opt for (2) 1850's in series, or I could stuff a 2200mah 4S into the fuselage - just not sure about overall flight time w/ power on. Any hints would be greatly appreciated.

Hey; where can I find props, hubs and spinners for this glider? I purchased my prop, hub and spinner for my Cularis at Hobby Lobby, but I'm not sure about size & application. Any ideas?


Thanks and God bless - "Rare"
Rare,

I think a single battery 4S 2200mah should be the better solution, I'm not sure if two batteries in series really so good, bcause by this way they should be have every time the same cell conditions (voltage, capacity).
About the prop: in the drivecalc there is only the E-flite power 15 and power 32 listed, if there were the power 25 listed it would be easy to calc the prop size, static thrust etc.
My opinion is that a 13x8 size would work. I use a axi clone (Similar to Axi Gold 2820/12 or 2826/10, E-Flite Power 15, E-Flite Power 25) from UH. and use a 13x8 prop.
Perhaps you can use the drivecalc and choose there the axi 2826/12, so you can see the difference when you use variable sizes of props. Here you can find the props I would prefer. Perhaps you can get them in different online shops in the US, I use this as middlepart, the big advantage of this kind of middlepart is that there is no screw direct on the motor shaft, the middlepart would be pinched on the shaft through the two screws. So there is a better shaft-hub connection.
My spinner , it fits very well and have also a good carbon look :-)
maybe you'll find these parts also in a us online shop.

Wolfgang
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Old Jan 05, 2008, 11:49 AM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
Nothing wrong with two packs in series as long as they're of the same age, condition, and are both fully charged when you put them in. Also, not flying to anywhere near LVC (usually discharging to no less than 25% of capacity) will ensure no problems..
..a
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Old Jan 05, 2008, 12:03 PM
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Germany
Joined Jan 2007
72 Posts
Quote:
Originally Posted by Andy W
Nothing wrong with two packs in series as long as they're of the same age, condition, and are both fully charged when you put them in. Also, not flying to anywhere near LVC (usually discharging to no less than 25% of capacity) will ensure no problems..
..a
Thats what I mean: Its easier to use one battery than two in series, so you don't have the problems about same condition, charged state etc.
Ok if the one big battery is faulty, you lost more $$, but its not so easy to replace one battery of a "series" pack if its faulty.
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Old Jan 05, 2008, 12:57 PM
I'd rather be Flying
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Nashville, NC, USA
Joined Mar 1999
2,977 Posts
Be careful using two packs in series. If they're not equally charged you'll over discharge the one with the lesser charge. It happened to a friend of mine. He has used a 5S and a 3S, made up of identical cells, and used in series as 8S. He's had many succesful flights with no problems of any sort.....until. One day he thought that each pack was fully charged but the 3S had not been recharged and it was subsequently severly over discharged in flight. He didn't realize he had a problem until performance fell off dramatically, and by then it was too late, the damage was done. No, LVC didn't save him. Double check each packs voltage before hook up.
Dave
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Old Jan 05, 2008, 11:18 PM
Go SIU Go
KC7MPV's Avatar
Russellville, AR, USA
Joined Dec 2007
15 Posts
dupe...sorry
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Last edited by KC7MPV; Jan 05, 2008 at 11:59 PM. Reason: duplicate...sorry
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Old Jan 05, 2008, 11:58 PM
Go SIU Go
KC7MPV's Avatar
Russellville, AR, USA
Joined Dec 2007
15 Posts
I posted a yet another proposed set-up on the "Part 2" thread, but seems like this one is staying more active so will re-post here. I've read and re-read posts...which have answered EVERY question I can think of...so thank you everyone!!

What are your thoughts on this "lower budget brushless" set-up??

ElectriFly 35mm Rim-Fire outrunner (GPMG4600) $55
Here are the specs from TH:
--Can Diameter: 1.38" (35mm)
--Can Length: 1.18" (30mm)
--Shaft Diameter: .16" (4mm)
--Shaft Length: .65" (16.5mm)
--RPM/V (kV Rating): 1450
--Weight: 2.47oz (71g)
--Propeller: 9x6E-12x6E
--Input Voltage: 7.4-11.1V
--Max. Constant Current: 35A
--Max. Surge Current: 40A
--Max. Constant Watts: 388W
--No Load Current: 1.8A

APC 11x8 or 12x8.5 or 13x7 folder on a 45mm hub $10
*Are the 12X8.5 and the 13X7 too big for this motor (12X6 limit)??*

ElectriFly 50 Surge/45 Cont. Brushless ESC (GPMM1840) $60

ElectriFly 10-cell 12V 2000mAh 4/5 sub-c (GPMP0353) $30
*I still need to stay with the NiMH's for now.
*Will I cook the 11.1 V motor with a 12 V battery??
*Or, do I play it safe with 9.6V (8-cell 2000mAh 4/5 sub-c)

Total Cost (w/10 cell) = $155 (not including a Prop adapter and spinner)

I asked for and got the Siren, as well as the 8-cell batteries, brushed 600 & ESC with 8X4 folder for Christmas, but I plan to return the brushed set-up since everyone agrees it's performance will be compromised.

Your thoughts matter!!

Thx! Doug
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Old Jan 06, 2008, 02:46 PM
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wpnguy's Avatar
lakeridge VA.
Joined Jan 2005
77 Posts
Help>
old story, too slow on the approach, tip stall and cartwheeled on landing. I managed to break off the outer panel of the wing and sheered the plywood joiner in half. The wing was glued together. Replacement wings are $70. at Tower Hobbies so I thought I would try to save mine first. The wing panels are in Ok shape but I have to figure out how to remove the glued in joiner block.

Any suggestions?
Thx.
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Old Jan 06, 2008, 04:16 PM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
Drill it out and use a carbon rod as a joiner - the bigger the better but probably 3/8 / 8mm is about all you'll get in there. Make a basic jig out of pine or poplar from the hardware store to ensure you drill both panels at the same angle, but if you drill it oversize you can glue the rod in with a heavy slurry of epoxy and microballoons or milled glass, make sure you have enough in there to fill any gap, and tape the panels together tightly with the tip supported until it cures. Use the best 30min epoxy you can find..
..a
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Old Jan 07, 2008, 02:58 AM
Isaiah 40:31
Rare Bear's Avatar
Joined Mar 2006
1,468 Posts
Quote:
Originally Posted by davecee
Be careful using two packs in series. If they're not equally charged you'll over discharge the one with the lesser charge. It happened to a friend of mine. He has used a 5S and a 3S, made up of identical cells, and used in series as 8S. He's had many succesful flights with no problems of any sort.....until. One day he thought that each pack was fully charged but the 3S had not been recharged and it was subsequently severly over discharged in flight. He didn't realize he had a problem until performance fell off dramatically, and by then it was too late, the damage was done. No, LVC didn't save him. Double check each packs voltage before hook up.
Dave
Thanks so much for the info, and as for everyone else, my sincere thanks as well - very helpful.

In short, I'm looking for the simplest solution battery wise w/o modifications to the fuselage structure - is it possible?

My motor weighs in at 190g, and I have access to 4S LiPo's, 3S LiPo's, and 2S LiPo's, which can be used in several ways. the 4S solution weighs in at 230g+, and all I'm looking for is a battery solution w/o making modifications to the internal structure.

If anyone has any ideas, I would be truly grateful. Thank you!!!


God bless - "Rare"
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Old Jan 07, 2008, 03:00 AM
Isaiah 40:31
Rare Bear's Avatar
Joined Mar 2006
1,468 Posts
Quote:
Originally Posted by fwolf15
Rare,

I think a single battery 4S 2200mah should be the better solution, I'm not sure if two batteries in series really so good, bcause by this way they should be have every time the same cell conditions (voltage, capacity).
About the prop: in the drivecalc there is only the E-flite power 15 and power 32 listed, if there were the power 25 listed it would be easy to calc the prop size, static thrust etc.
My opinion is that a 13x8 size would work. I use a axi clone (Similar to Axi Gold 2820/12 or 2826/10, E-Flite Power 15, E-Flite Power 25) from UH. and use a 13x8 prop.
Perhaps you can use the drivecalc and choose there the axi 2826/12, so you can see the difference when you use variable sizes of props. Here you can find the props I would prefer. Perhaps you can get them in different online shops in the US, I use this as middlepart, the big advantage of this kind of middlepart is that there is no screw direct on the motor shaft, the middlepart would be pinched on the shaft through the two screws. So there is a better shaft-hub connection.
My spinner , it fits very well and have also a good carbon look :-)
maybe you'll find these parts also in a us online shop.

Wolfgang

Wolf -thank you!! Very helpful!!


God bless - "Rare"
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Old Jan 07, 2008, 04:05 AM
Registered User
Germany
Joined Jan 2007
72 Posts
Quote:
Originally Posted by wpnguy
Help>
old story, too slow on the approach, tip stall and cartwheeled on landing. I managed to break off the outer panel of the wing and sheered the plywood joiner in half. The wing was glued together. Replacement wings are $70. at Tower Hobbies so I thought I would try to save mine first. The wing panels are in Ok shape but I have to figure out how to remove the glued in joiner block.

Any suggestions?
Thx.
same happened to me ;-( I 've fixed it by the method from Andy W.
Next will be that I will laminate the wing completely, so I hope it will be get more durable.
Wolf
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Old Jan 07, 2008, 04:20 AM
I'd rather be Flying
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Nashville, NC, USA
Joined Mar 1999
2,977 Posts
Rare, The Power 25 is about a 600 watt motor, according to specs. They suggest 3S to 4S and an11/8 to 14/7 prop and a max burst current of 44 amps
I ran a calc and I feel that a 13/8 on 4S would be too much. I get 73 amps, 972 motor watts and 190 watts lost as heat. I think that's pushing that motor pretty hard.
On 4S an 11/8 looks better by calc, 49 amps, 674 watts and 101 watts lost as heat, much closer to the motor specs.
On 3S a 13/8, 48 amps, 488 watts and 90 watts lost or a 14/7, 52 amps, 532 watts and 104 watts lost. should be within the motor's capabilities.
All my recommendations assume good throttle managemant, not WOT for the whole flight
These are just calculations and you must actually measure any set up that you use. However I have confidence that these numbers are in the ball park and should give you a good starting point.
Dave
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Old Jan 07, 2008, 08:39 AM
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Germany
Joined Jan 2007
72 Posts
@rare

perhaps you should really choose the axi 2826/12, for this motor there are datas in the Drivecalc available. Its not much more expensive than the eflite.
For example: With a 13x8 Aerocam you will get a static thrust of about 2500 gramm, at 37 A, the speed would be around 75km/h. These are the results of drivecalc in combination with a 4S 2200 Dualsky Lipo pack. Running time at full throttle would be about 3:20 mins. But is full throttle really necessary with this package ?

wolf
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Old Jan 07, 2008, 11:23 PM
Isaiah 40:31
Rare Bear's Avatar
Joined Mar 2006
1,468 Posts
Quote:
Originally Posted by davecee
Rare, The Power 25 is about a 600 watt motor, according to specs. They suggest 3S to 4S and an11/8 to 14/7 prop and a max burst current of 44 amps
I ran a calc and I feel that a 13/8 on 4S would be too much. I get 73 amps, 972 motor watts and 190 watts lost as heat. I think that's pushing that motor pretty hard.
On 4S an 11/8 looks better by calc, 49 amps, 674 watts and 101 watts lost as heat, much closer to the motor specs.
On 3S a 13/8, 48 amps, 488 watts and 90 watts lost or a 14/7, 52 amps, 532 watts and 104 watts lost. should be within the motor's capabilities.
All my recommendations assume good throttle managemant, not WOT for the whole flight
These are just calculations and you must actually measure any set up that you use. However I have confidence that these numbers are in the ball park and should give you a good starting point.
Dave

Dave, Wolf - thanks for the info - you guys are great! Truthfully, I'm just looking for a battery setup that will work w/o modifying the fuselage i.e., removing the wood structure within. Is this possible?

As I mentioned, my motor weighs in at 190g, and I'm not adverse to using a bit of lead. So, if anyone knows of a suggestion on a battery that will not need the frame modified, I would be very grateful. Thank you!!


God bless - "Rare"
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Old Jan 07, 2008, 11:26 PM
Isaiah 40:31
Rare Bear's Avatar
Joined Mar 2006
1,468 Posts
Quote:
Originally Posted by fwolf15
@rare

perhaps you should really choose the axi 2826/12, for this motor there are datas in the Drivecalc available. Its not much more expensive than the eflite.
For example: With a 13x8 Aerocam you will get a static thrust of about 2500 gramm, at 37 A, the speed would be around 75km/h. These are the results of drivecalc in combination with a 4S 2200 Dualsky Lipo pack. Running time at full throttle would be about 3:20 mins. But is full throttle really necessary with this package ?

wolf

Wolf - sorry, but I already have the Eflite Power 25, so I'm simply looking for a battery combo and prop setup. Thanks anyhow!!!


God bless - "Rare"
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