RC Planes

Looks like you are doing well with it. :) Just try to get it landed a bit sooner in the field next time. :p

You really should get yourself a wattmeter as they are very handy to see how much power you are pulling. Get something like this.

http://www.giantcod.co.uk/wattmeter-lipo-tester-p-403900.html

Should be all good with the new motor, but see I said you would have plenty of power even with the stock motor. :p Wish I had got my planes sorted this week as today is lovely weather for flying.
 
lol yeah, the trees were coming up pretty quickly at the end. :p

I will order one of those later, I also need a voltage meter always available, which I think I'll mount externally so I can look at it when it lands.

Took it out earlier and didn't have much fun with it cos it was so damn windy. Didn't realise how windy it was until we got to the park and there were a bunch of huge kites flying about. I think that if I didn't have the uprated motor then it would not have made any headway against the wind. It also just limited me to flying into the wind at full throttle and then back again.

I'll be flying again in the week when it's calmer. Didn't really enjoy it much today, particularly as it was so ruddy cold. I almost slammed it into the floor attempting to land and my fingers were like icicles after the freezing wind.
 
I never like flying in wind like that to be honest, I can't be bothered with it.

I've just had to chuck 2 of my lipo's as I have found them to be puffed, so they are in a bucket of salt water right now discharging. Good thing lipos are so cheap now!
 
all salt water does is disvolve the aluminium tabs it doesnt discharge the pack.

its a stupid old wives tale, what your suposed to do is stick the batery outside in a bucket of sand with a car bulb or some such drawing the energy from the pack slowly until its completely drained

btw if your good with a soldering iron u can swap out the puffed cell for a good one
 
If I am honest I'd rather not take a lipo apart, I don't have a problem soldering but for the cost of these things I don't risk it.

Bit late now as it is in a salt water bath, not sure what I can do now to remove the charge (cells were at 4v each before!).
 
Herro sexy peoples. Any chance someone could recommend a cost effective solution to my problem?. :). Basically I'm getting around 12 mins out of this battery:

batterya.jpg


(St models Discovery)

I want more!, I want 25 mins+. It's as though every time I get into it, set trim etc, I'm running out of battery. And because I'm a noob I tend to be cautious and use too much power to avoid stalling etc. Either way, if anyone has any cost-conscious recommendations t'would be much appreciated :].
 
arknor said:
get a bigger batery :P

isnt 15c discharge low? i use 25c in my heli and its probably got a lesser motor than your plane.
4200kv
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15C use to be pretty standard, if anything you got 10C ones too back when lipo's were newer. Looking round they are lipos back from 2004! That'll mean 1C charge at max and I do wonder how much capacity they still have these days.


benneh,

What weight is the pack? Best way, get a 2nd battery pack!

You look like a perfect person for a Gen's Ace (which are the ones people like to buy on a budget) and even better they come with a deans connector as standard on the larger batteries. I suggest this one as long as the weight of your current pack is 130-180g range.

http://www.giantcod.co.uk/gens-1800mah-lipo-battery-p-406463.html

Edit - Looking on the net with the plane you have people also go all the way up to 2500mah, so you could look into the slightly larger capacity packs at the same time. If it can take an extra 50grams on the AUW then go for the Gens Ace 2200mah.
 
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GenAce are the ones I got from GiantCod. What do the better/more expensive ones offer you? Longer life?

What is the voltage of a fully-discharged Lipo btw? After running the plane yesteday in strong wind with lots and lots of full throttle, and also the first time I took it out with the stock motor, the voltage drops to about 11.2-5v. What is the lowest I can go?

Also, after yesterday's faffing about trying to set up the plane in the park I am definitely going to have to tidy up the cables and sort out a means of easily securing batteries. Took about 20 minutes in the freezing wind trying to get it right.
 
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Don't go below 3V per cell, so you still have plenty left as yours is at 3.73v per cell. Does your charger tell you how much capacity it has charged up in the battery? If so compare that to your rated capacity to get a feel for your voltage curve. Have a look on the link, look at the voltage graph at how lipos act. What voltage cut out have you got on your speed controller?

Better lipos (as you can see in the graph) will last longer or give more voltage throughout the use. Could even do both as you can see the Gens Ace compared to Loong Max Tipples.
 
Yeah it does actually - I did a charge earlier but I didn't think to look at how many mAh used. I've got another one to charge - using in parallel which must be why there's plenty left - so will see how much it soaks up. Is there any loss in how many mAhs used vs how many are put back in?

Those Genace seem to be the best by some margin looking at that graph. I have some Turnigy ones as well; not sure how those stack up.

When you gonna get your stuff back in the air saitrix? Would be cool to see your stuff flying about. :cool:
 
Putting an order for a few stuff in tonight (from Giantcod) to get both mine and my Dad's planes back up in the air. So hopefully in a week or so unless the weather turns very nasty, I am a bit of a fair weather flyer. :p

Very minimal difference so have a look on the charger and see how much it puts in it to get a feel for it. What voltage did you set on the speed controller to cut out at?

What is a shame is the amount of stuff I'm chucking out. About 12 batteries, 4 speed controllers, 3 motors, 1 receiver and a few other various things. All just outdated these days so no point keeping hold of them.

I have a 50" Galaxy Models Magician to build, meant to be for nitro but I will run it with 800-1000W motor setup I think. Need to work out exactly but that will be my next project, and possibly get building my Dad's advanced trainer as he is determined this year to get off the trainer lead. :p
 
alexthecheese said:
GenAce are the ones I got from GiantCod. What do the better/more expensive ones offer you? Longer life?

What is the voltage of a fully-discharged Lipo btw? After running the plane yesteday in strong wind with lots and lots of full throttle, and also the first time I took it out with the stock motor, the voltage drops to about 11.2-5v. What is the lowest I can go?

Also, after yesterday's faffing about trying to set up the plane in the park I am definitely going to have to tidy up the cables and sort out a means of easily securing batteries. Took about 20 minutes in the freezing wind trying to get it right.
Click to expand...

I use the gens ace and they are great.

velcro cable tidies epoxied into the body is a great way of securing battery's. Just make sure you have lots of air over your electronics for cooling and all will be ok.
 
benneh said:
Herro sexy peoples. Any chance someone could recommend a cost effective solution to my problem?. :). Basically I'm getting around 12 mins out of this battery:

batterya.jpg


(St models Discovery)

I want more!, I want 25 mins+. It's as though every time I get into it, set trim etc, I'm running out of battery. And because I'm a noob I tend to be cautious and use too much power to avoid stalling etc. Either way, if anyone has any cost-conscious recommendations t'would be much appreciated :].
Click to expand...

You'll get 25+ mins out of a powered glider but i think you'll be lucky to get any more than 12 mins out of it without making it seriously lighter. I wouldn't go off throttle either as youll tip stall without any dihedral at low speeds

I've found that putting bigger batteries in doesn't really = longer flight times as you have to fly a higher weight around.

So if you really want longer flights, get a powered glider as I said before, Hawksky or even the one alex has got will be great. Just get it up high, cut the throttle and glide about, staying into wind.

You should be able to use the same radio gear and battery's on it so cost saving there. I've had 35 mins on the hawksky on good 15mph windy day. Only came down because my neck was hurting from looking up all the time :D A friend with a large foam powered glider hit 45 mins.
 
Thanks for the replies guys :]. I think maybe the best plan for me is to have 3-4 batteries (slightly larger packs in addition to my current battery), it would be nice to have a super long flight time, but then at the same time a big portion of the fun (read: scary ******* danger) is taking off and landing, so several landings during a flight can't hurt :D.

As for powered gliders. I like the idea of that, a less frantic more refined option. Maybe for my 2nd plane I'll look into that :], for now though I want to get a bit more time out of my trainer. $$$$ ;p
 
Sounds like a plan, how good a charger have you got? You might be able to do parallel charging with identical batteries if so. And whats to stop you having two working planes. :p

Well I have ordered all the bits to get flying again. So depending when I get it and the weather I should be back up in the air. Then to get my 50" nitro to electric conversion project going, for anyone who knows its a Galaxy Models Magician. Just need to work out how many watts I should be pulling to replace a .40-.46 engine.
 
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I've been doing a bit of reading before work on the old props/motor/thrust/amps/watts combos out there, and it all seems a bit open ended. Basically not as simple as I hoped. :p

I was looking at something that would provide 1kg of thrust (just out of interest on www.Flybrushless.com), but the speed is only 60mph, where as a less 'powerful' setup with a smaller prop provides much faster speed - 116mph but 500g of thrust.

I thought it might be a case of whop on a bigger motor, with a bigger prop and you'd go faster, but as you're doing less RPM with a bigger prop, you might get more thrust but I'm guessing as the speed is lower, you won't necessarily go any faster. Is that right?

Where do you start? My plane with 2 x 3s 2200mAh is about 1.4kg. I haven't tried it with the 2212-6 motor on a calm day yet, but am sure it'll be fine, but if I wanted even more speed, where should I look first? Alternatively, given this is a large glider like thingy as taggart is saying, if I wanted sheer longevity of flight, am I better off with lower speed but more thrust? Confusing. :p

I'm not sure this is a long-term reliable 900watt solution that you'd be after saitrix, as it only weighs 120g or so, but there's a video here that reviews the motor with 3s/4s battery setups and it pushes 925 watts with a 4s battery. Not sure about the speed though. ;)

Makes me tempted to get some new batteries, however. :p

http://www.hobbyking.com/hobbyking/store/__15169__NTM_Prop_Drive_Series_35_36A_1800Kv_875w.html

 
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Right, you are opening a big subject here.

First of all lets start with props. As a basic rule of thumb larger diameter increases thrust, larger pitch increases speed. The setup that produces 1kg thrust just doesn't spin the prop fast enough to be able to go any quicker, it always is a toss up between thrust and speed at the same wattage. So this is why it is important you understand what type of flying you will be doing with the plane so you get the correct type of setup.

Now we will go onto the motor, as you may have noticed you can often get the same motor but in different kv's. Now kv tells you how fast the motor can spin (unloaded) per volt. Though as the kv goes up the effective torque the motor has decreases, so once again it is a balancing act. But as you may have guessed the battery choice vastly alters what kv you require. Now motors have an efficiency curve, which I have a website link (will get you it when I'm home) for working out the efficiency curve and roughly where certain props land on the curve. So really the battery, motor and prop choices all have to go hand in hand to produce an efficient setup.

Now to do with your setup, when you get to fly it on a calm day try to work out whether you have more thrust that you could get away with. If so then drop diameter of the prop down and the pitch up, that will land you a quicker plane but will slow down more when climbing at a high angle.

That motor you have linked me is no where near big enough, it will so inefficient at that power, much better to go up to the 200-250g range. The motor is said to be rated to 36A, so to work out the watts at 4s it would just be 36*14.8 which is 533W. It does seem like a 4s 3000mah battery seems decent, or maybe even 5s. For 4s I will have to pull 54-67amps and at 5s 43-54amps. Of course I will have to decide what batteries to use before I can really make a motor decision.

Now all of that is only a very basic overview, there is more to it then I have mentioned but it should be a good enough start. :p
 
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