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Old Jan 04, 2012, 07:45 PM
Fly it like you stole it !
bobbit4447's Avatar
Australia, QLD, Coolum Beach
Joined Oct 2011
372 Posts
Those struts look promising...do we have a load rating? in the case of the Viper I would expect each leg to handle around 1,400g static each..more on landing. I think the wheel size is OK..its always going to be a compromise, the space limitatations on the wing wont allow much more. I found it easy to drill out the hole in the legs with a portable drill, just go 0.5mm at a time. I also bushed the mechanisms, with bushes made from pre 2.4 aerial, loctite in place they work perfecto. Pics look good fg.
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Old Jan 05, 2012, 04:45 AM
TakeOff=optional,Landing= Must
fg1972's Avatar
Australia, Melbourne
Joined Jul 2010
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Time to decide on batteries, so many combinations to choose from. Am looking for reasonable run time ideally 3-5 minutes without carrying too much weight.
Thinking about the following 4S batteries in series for an 8S setup

1-ZIPPY Flightmax 5000mAh 4S1P 45C @ 596g
2-Turnigy 5000mAh 4S 40C Lipo Pack @ 578g
3-ZIPPY Flightmax 5000mAh 4S1P 40C @ 566g
4-Turnigy 5000mAh 4S 35C Lipo Pack @ 554g

or save a little bit of weight and reduced run time
5-ZIPPY Flightmax 4500mAh 4S1P 45C @ 527g
6-Turnigy nano-tech 4500mah 4S 35~70C Lipo Pack @485g

Based on capacity, C rating, weight, price and local availability, I'm leaning towards the No.3 option.
What are your thoughts?
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Old Jan 05, 2012, 06:05 AM
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ive tested those batts in different capacitiesall i would recommend going with the 4400mah 65-130c nano techs
The zippies always have less capacity than the equivalent nanotechs. The 40c zippies also have more internal resistance than the 35-70c nanotechs

The 65c ones though.. Oh well.. Theyve got the power. I say go with those. Despite the extra cost if there is any in final analysis
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Old Jan 05, 2012, 03:05 PM
Fly it like you stole it !
bobbit4447's Avatar
Australia, QLD, Coolum Beach
Joined Oct 2011
372 Posts
In our club nanos are generally percieved as superior. Freight can be a problem as they go via the dumb Swiss Post, whereas others are ex AUS stock - 2 days.
My proposed setup......using 6S motor, 86A max draw
2 x 2,200 25-50C 6S Nanos in parallel -415g x 2
plus....
Zippy LiFe 1800 - 136g for RX,servos & landing gear.
See any problems ?
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Old Jan 05, 2012, 06:20 PM
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fg1972's Avatar
Australia, Melbourne
Joined Jul 2010
427 Posts
Bobbit, your combo looks ok, do you reckon you will get the required thrust on 6S and is 4400mah capacity sufficient?
Have you measured current draw on 6S?
Which motor you using again?
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Old Jan 05, 2012, 06:28 PM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
Joined Aug 2008
3,226 Posts
Quote:
Originally Posted by fg1972 View Post
Time to decide on batteries, so many combinations to choose from. Am looking for reasonable run time ideally 3-5 minutes without carrying too much weight.
Thinking about the following 4S batteries in series for an 8S setup

1-ZIPPY Flightmax 5000mAh 4S1P 45C @ 596g
2-Turnigy 5000mAh 4S 40C Lipo Pack @ 578g
3-ZIPPY Flightmax 5000mAh 4S1P 40C @ 566g
4-Turnigy 5000mAh 4S 35C Lipo Pack @ 554g

or save a little bit of weight and reduced run time
5-ZIPPY Flightmax 4500mAh 4S1P 45C @ 527g
6-Turnigy nano-tech 4500mah 4S 35~70C Lipo Pack @485g

Based on capacity, C rating, weight, price and local availability, I'm leaning towards the No.3 option.
What are your thoughts?
I would defantly go with option #6. Youve already added a ton of weight by adding retracts. I use the Nano 4500 45c And I dont even have retracts.

By the way.. thanks for getting off the retract decussion. Now I can return to posting

Quote:
Originally Posted by bobbit4447 View Post
In our club nanos are generally percieved as superior. Freight can be a problem as they go via the dumb Swiss Post, whereas others are ex AUS stock - 2 days.
My proposed setup......using 6S motor, 86A max draw
2 x 2,200 25-50C 6S Nanos in parallel -415g x 2
plus....
Zippy LiFe 1800 - 136g for RX,servos & landing gear.
See any problems ?
B
Bob..are you planning on useing 2200mah batteries? That would make for a very short flight, would it not? Even with retracts..I would think you could carry at least 4500s since your only going 6s. Using a very light setup is a great idea, but woulnt at least 4000 be better..
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Old Jan 05, 2012, 06:53 PM
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fg1972's Avatar
Australia, Melbourne
Joined Jul 2010
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Bobs says the 2200 batteries are going in parallel so will have 4400 capacity.
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Old Jan 05, 2012, 07:07 PM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
Joined Aug 2008
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Quote:
Originally Posted by fg1972 View Post
Bobs says the 2200 batteries are going in parallel so will have 4400 capacity.
yeah...I figured I read that wrong
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Old Jan 05, 2012, 07:40 PM
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fg1972's Avatar
Australia, Melbourne
Joined Jul 2010
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I am planning to use a small 2S 1800mah battery (~100g) via three separate 5 Amp regulators (8g each) to distribute power to servos, retracts, rx.
Or would I be better off using one larger heavier BEC and connecting it to the main batteries?
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Old Jan 05, 2012, 08:09 PM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
Joined Aug 2008
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Keep it simple my friend. Here's what Ive been using for the last 3 years on all my Jets.
http://www.hobbyking.com/hobbyking/s...for_Lipo_.html Just solder a connection to the ESC battery teminal. plug the BEC into that...and voila!
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Old Jan 05, 2012, 08:19 PM
Fly it like you stole it !
bobbit4447's Avatar
Australia, QLD, Coolum Beach
Joined Oct 2011
372 Posts
fg, vett
Quote:
Originally Posted by fg1972 View Post
I am planning to use a small 2S 1800mah battery (~100g) via three separate 5 Amp regulators (8g each) to distribute power to servos, retracts, rx.
Or would I be better off using one larger heavier BEC and connecting it to the main batteries?
I guess its a personal thing.. I prefer 6.6V Life, or Lion... to keep control & power functions seperate....no BEC

Quote:
Bobbit, your combo looks ok, do you reckon you will get the required thrust on 6S and is 4400mah capacity sufficient?
Have you measured current draw on 6S?
Which motor you using again?
Using CS/12 blade combo (X-flite) initially to get going. The advertised current has been confirmed in another thread.
It will be pretty tame probably 0.8/1.0 thrust/weight but then I think this will be a slippery birdie. Yeah 4,400 is pretty light, I'm OK with 4min flights. I think 2 packs, either side of nose gear & keep the weight down low.
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Old Jan 05, 2012, 08:49 PM
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fg1972's Avatar
Australia, Melbourne
Joined Jul 2010
427 Posts
Thanks Vetts for the BEC link. I am concerned that this BEC is rated at constant 3A and max 5A.
I wonder what the max potential current draw is with all those servos stressed out while flying, plus retracts. You could put two or three of those BEC's in to distribute the load but this too adds weight, ie three BECS is 64grams already.
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Old Jan 05, 2012, 09:04 PM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
Joined Aug 2008
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Its not a problem. As Ive said..Ive been using them for 3 years. I have a buddy that installed a Wheattronics thing in his turbine jet. If your not aware of this thing. Its a total telemetry thing that tells you where every single micron of that power is going. For the longest time we have always been trained to think that you need at least a constant 6a per servo all the time. He deciphered the info and incredibly.. the elevator servo that you would think drew the most amps..only drew an average of something like .03 amps with a peak of 1.1 amps during slow flight while pulling up. Thats amazing! Dont forget this was on a 30lb jet with huge digital servos.

Not trying to sway you..Im just saying

Here's a tip for you on how to cut your nose gear doors if you havnt already.


Using a dremil is pretty tricky and donsnt always provide a clean and straight cut. What I do is use dymo tape. You remember the old days when lable machines used to press letters into tape and then you peel off the back and stick it. This tape is actually plastic and provides a good solid raised edge. Take your #11 exacto knife and break the tip off. Turn the knife over and scribe with the back of the blade. Go very gentle with the first 3 passes and then you can add more pressure once youve made a good and straight groove. A few more passes and in no time at all, youll have a perfectly straight and thin line cut thru the fues.
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Last edited by vettster; Jan 05, 2012 at 09:34 PM.
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Old Jan 06, 2012, 06:29 AM
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Quote:
Originally Posted by vettster View Post
Keep it simple my friend. Here's what Ive been using for the last 3 years on all my Jets.
http://www.hobbyking.com/hobbyking/s...for_Lipo_.html Just solder a connection to the ESC battery teminal. plug the BEC into that...and voila!
carefull there.. not a good BEC.. I have 3 of those. they work on small apps but not oon jets. and definetely not at 6volts.
there is voltage drop up to 3.8v when servos are used.. definetely not a 5amp BEC
especially for us spektrum guys we don't wanna see any brownouts with the viper jet.
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Old Jan 06, 2012, 06:31 AM
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if youread the reviews carefully even guys that give 5 and 4 stars mention that it won't work on 6volts
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