tIANci

Sig - I got the solution to to your frustrations about the small EP planes ... hope you like this. Its my current project!!! But I do have one problem, the darn LadyBird can out manuever any of my planes!!!

sigrun

Ehehe .....tIANci you've been infected by the e-bug bad!

Actually the kind of scale I prefer to fly is [link=http://www.youtube.com/watch?v=umnNKLBSGhY]this[/link] although today I have to fly larger and faster, which doesn't mean I don't still enjoy flying [link=http://www.youtube.com/watch?v=vcCwe1cmOLU]this[/link], or won't fly [link=http://www.youtube.com/watch?v=-eEyjLCUGIY]this[/link]. Size is no more about silly status seeking self-identification or polarisation with me than it is about loving all things aviation since I was about nine. Just as I enjoy(ed) the simplicity of control-line combat for the sheer enjoyment of the adrenaline engaging rapier like joust that it represents.

In the end it's all a matter of prioritised preference and of course, affordability when 'the company' ain't no longer payin' for the ride. That said, like it or not, Reynolds and mass dictate that small really does 'suck' from an aerodynamic perspective.....It's not intended a personal slight, merely a a comparative for those incapable of discerning that distinction.

tIANci

Sig - I know I have been infected bad ... even sold my YS110 and SA100!!! Both were superb running engines. Wow you fly real planes? I went up on a Cessna 172 once ... before boarding I asked the pilot one thing ... how well does she glide on a dead stick ... he assured me it was pretty good ... so I went for my flight! For me it will stop at an 80" plane, that is the biggest I am willing to handle, anymore and its a pain for transport and storage. I sitll love my small EP planes powered by 400 sized motors ... I love anything flying I guess.

I think people who are into CL need a lot of help ... heheheheee ... tried it once, a so called slow plane on a slightly short line, I did like half a tank and I got SICK! What a headache ... I will never go near them again.

ELTIGRE

sorry to disagree with you but ive been flying "40 size electrics " for years & the battery packs ( which dont cost $250) have out lasted many, many gallons of fuel.and i fly for 7-10 min on charge -about what I do on glow as average by choice. your also neglecting to ad cost of glow plugs ,which is not exactly cheap anymore and other maintenance which adds up as well. Ive flown plenty of glow as well-and I dont miss the mess of glow which is hard ( but not impossible ) to reduce. operating costs of electric are low.there is less maintenance & rarely will one quite on you unexpectedly.you just had an expensive set up. the same could be done for glow as well. electric planes generally out last glow due to less vibration on the airframe . proven fact.

ELTIGRE

your quite wet on some of your costs. Ive had batteries last for years , not a few flights. "adding" the cost of a Lipo charger when you need one anyway is false analogy. and depending on what your flying, notthat expensive.especially since with glow you practically need a power panel, fuel pump, starter, 12 vt battery. a back up ni-starter battery is good insurance too. your spending lots on glow fuel, just not all at once.
charge for 1 hour??? you can tell you dont fly much E. 20 minutes is more like it.yes, you should have 2 packs , three is a bit much but not a bad idea.still out last gallons of glow fuel & I can prove that by experience.electrics do not have to be expensive .AND there are plenty here who are rationalizing some of the glow expenses.
I like how the most expensive Electric stuff is compared to the average glow equipment as a "fair " cost comparison. if its all so bad WHY is electric overall becoming cheaper on average ? why is there more & more E coverage ( and flyers )out there? this is not the dark days of the 70's when electric was the realm of the experimentor. glow had its problems ( and still does actually) in its developemental phases.

ELTIGRE

electrics can be costly but that is not always the case . the technolgy matures & goes mainstream it lowers the cost.also & dispite one post here to the contrary , electrics cost about the same , on average over time .there are always exceptions you can point to in either case. electrics generally last longer as long as you take care of your batteries which you should be doing for glow as well. brushless motors are not used much outside our hobby so there is limited incentive to use& develope them.the fellows are accepting the brushless & Lipos because they get performance from them. there will always be issues even with glow -its just the majority are not considering the things you must deal with on glow engines since they are used to them. I find I need more equipment to fly glow as well.if electrics are still such a problem you would not see the "explosion " of offerings in the modeling press including conversions to electric which work very well. YES, there are those that dont live up to their claims - neither did many glow planes in the 50's & 60's.
diesels don't find much following in the states because their main advatages- fuel economy & torque ability to swing large props has been suplanted by four strokes & electrics. if you actually see( and smell) a diesel run you might understand why it is not so popular. to many they stink to high heaven and leave a large mess that takes care of all but the toughest finishes & does a number on your decals.storing diesel in quantity can be a problem as well since the either can leak out if not stored well.

opjose

I see this quoted all the time.

Please tell me how you are doing it?

I'd be happy with a 20 minute charge cycle and two or three packs.

Everyone who I've found that charges their batteries in under an hour is charging at greater than 1C rates, which is usually touted as not healthy for "normal" LiPo longevity and requires higher cost packs or more exotic batteries such as the A123's.

As it is in my usual 3S2P configurations I have to wait 2 HOURS to charge one set of batteries for flight unless I use multiple chargers or chargers with ganged charging capabilities. That still reduces things to 1 hour at a 1C charge rate so I can keep my batteries around as long as possible.

The upside is that I can often get as much as 28 minutes off of this charge, so four sets of packs would be enough to get by for the day. ( I do try to keep my planes flying continuously as much as I am able. I consider 2-3 hours of actual in flight time a "good" day... )

However when I factor in the costs of all of this ( and I agree that most of the support equipment costs are a bit superfluous as you have to pay that no matter what, for electrics or glow... ) and the longevity of the packs, glow still comes out cheaper...

That is until the costs of the batteries drops to about 1/3 of where it is now or 1/2 of the cheapest prices I've been able to find.

At that price point things break far more evenly in the .40 through .90 range.

At the moment the limiting factor still seems to be the batteries in the mid range plane sizes. Once you start moving up however, motors and ESC's also start making things prohibitive again.

e.g. a DA50 to DA250 equivalent in an electric setup is still quite expensive for one of those hacker "monster" motors combos, let alone the required ESC's and power packs.

tIANci

Actually, the cost of EP is prohibitive on the batts front. I can tell you that motors and ESCs are already cheap, I know for a fact that a 160 sized motor equivalent is only USD65 from factory direct and a 90A HV ESC only USD95. Unfortunately, prices of lipos will take a while to drop to 33% of current prices. Guess to go EP we need to syat within Speed 400 sized planes to keep it cheap ... if not just bite the bullet and buy the big batt packs. For me to enjoy my smaller planes I need about 6 flight packs for a good flying session. If they are 3S1P 2,200 mAh packs then its not too bad, when we get to 40 sized planes then it really stings. One of my pal has like 12 flight packs, he has spent tons on batts but he is very happy.

stockdaddy

That could be a vague of quote as saying i can't wait flash memory to drop so i can switch from film to digital.

Can i actually pin you guys down and get you to state what price you base this on? What brand? How many cells? What capacity?

I don't really see the point of having more than 3 packs. You do have to plan things out when you buy so you don't need different sized packs for different 40 scale planes. If you are mixing gas and electric flight, you can likely do with less packs.

This charger is pretty good for quick charging mutiple packs:
http://www2.towerhobbies.com/cgi-bin...?&I=LXKAU0&P=0

B.L.E.

A lot of people also land before the battery is hitting the ESC's low voltage cutoff. If you only fly out 60% of a battery's capacity, guess what, it doesn't take an entire hour to charge it back up again. Deep cycling is also supposedly hard on batteries.

tIANci

Stockdaddy - you need to realise that high discharge lipos are used mainly by RC hobbyists ... flash memory has a higher number being used. How can it be said that lipos will drop their prices that much so soon? Look at leading brands (FP/TP/PQ/Hyp), they are not dropping prices, only releasing higher C batts at the same price. The prices are "coming down" a bit because LHS are dropping their margin to increase volume. The LHS buys them for like 30%-35% of the retail price.

The only cheap lipos are from China and they always bloat, I seen too many used and too many failures. They call it 20C 2,200 mAh packs but when used on TRex 450s they bloat, those helis do not pull more than 35A WOT. Looks at NiCds and NiMH, its used by other than RC hobbyists so it gets cheap.

Also 3 packs hardly give you much flying time if you are getting into things ... use Pack 1 and its warm, needs some time to cool down, about say 20 mins, charging time at 1C for 75% capacity is about 45 mins to 60 mins. By then you finished Pack 2 and 3 as we also talk a lot at the field ... so by the time you get to Pack 3, Pack 1 is ready and you are now charging Pack 2 ... that's about 1.5 hours. If we are talking about hanging out for 4 hours at the field then yeah ... 3 packs are ok. On Monday I finished 5 packs in one late afternoon session of just under 2 hours. That was just on the maiden of my OK Models Ultimate E. Again, it depends on how crazy we are at the field.

opjose

Sure. I'll let you vivisect my calculations. Be gentle.

In doing all of this I was looking at the costs of replacing a typical .32 engine with electric power.

To do so I would need at least two 3 cell 2200mAh packs per "run" in a 3S2P configuration ( though I did state this before ) to bring things up to 4400mAh 11v as a minmum for a typical 600w+ motor.

The battery pricing I used was based upon a LOW EBAY price of $42.00 USD I found for cheap 2200mAh 3S packs and a more realistic $65.00 per CHEAP pack.

To in turn be able to "fly all day" I would at the minimum need three to four of these packs or $65.00x2x4 $520.00.

I purchase fuel at $11.00 per gallon. That gives me 47 gallons of fuel for the same expense.

With typical consumption being approximately .5 fluid oz per minute of flight time on a typical .32 engine ( this is conservative on an engine this small ). That equates to 256 minutes per gallon or 4.2 hours, which is about what I see at the field.

So for the price of the batteries I would get approximately 196 flight hours with glow.

Packs are supposed to be good for at least 75-100 cycles with some people reporting much more others with failures within that range. I'll use a optimistic median of 120 cycles.

With the above 3S2P configuration in a Super Sportster EP, I'm getting about 20 minutes worth of flight time.

That constitutes 588 cycles over the same 196 flight hours.

With FOUR sets of packs I would need to keep each pack working for 147 cycles, to break even with glow.


The above is not based upon the more expensive and hopefully reliable Thunder Power, etc. pricing for packs, so once you factor those in, things get more expensive.

Is 147 cycles doable with fairly cheap packs and above 1C charge rates? Marginally.



As you move up to the .46 range prices for batteries in particular, start climbing and glow looks more attractive.

Yes this is exactly what I have done with my SuperSportster EP.

To get the same performance as a .30-.32 engine I'm forced to run ( at least ) 4400mAh 11v.

The best way to leverage the batteries is to purchase 2200mAh packs, so that I can use these alone or in combination on other planes as well.

In spite of this I need 6-8 3S 2200mAh packs so I can charge while flying without interruption.

I love the ease of the SS EP setup this way, and I would love to electrify larger planes, but when I do the math, it doesn't work out for me... glow ends up being cheaper once I'm into and beyond the .40 range.

Below that you can almost ( but not quite ) "break even", though the difference is small enough that the added convenience of electrics tends to offset this a bit. If the packs were cheaper things get much more attractive for electrics.

e.g. when I know I only have an hour or two after work, I'll toss an EP into the trunk before I leave for the day. On weekends however, I favor the glows.

opjose

The packs on the SS EP run for approximately 24-30 minutes. I always land at the 20 minute mark for safety.

It still takes a good 50 minutes to charge the battery unless I up the charge rate.

stockdaddy

You can easily get 3d performance on 2500 to 3000 mah 11.1volt pack.

You can get longer run times by running huge packs but then you take away performance. On a sport 40 scale a 10oz tank will get you around 7-10min of flight time with .46 engine. A good electric conversion shouldn't be heavier than a gas setup fully fueled. You can run a 40 scale plane on 14.8v 3000mah setup getting near 800 watts of power or 6 lbs of thrust.

I think in terms of overall cost, what you really are saying is not that we need cheaper batteries, we need longer lasting batteries with your number of 125 charges per battery. The amount of charges you get per pack can vary widely from one brand to another and on how close to specs you run the packs.

tIANci

stockdaddy - you got it right ... we need cheaper batts and batts that are reliable (if its not abused). I would be happy if batt prices were to drop by 30% and we can confidently say they will last 100 cycles. If we pull the batts at their recommended max discharge rate, most batts will lose about 15%-20% capacity after 50 cycles. The 200 cycles test is usually done on 1C-2C discharge rates.

Are you sure you can get 800W from a 4S set up? You are talking about pulling close to 80As. That's really a lot of amps for a 4S set up.

opjose

Unfortunately I can't.

Not with the run times I desire of more than 14 minutes on a 3 lb+ plane.



I get a good 24 minutes ( that is where I have my timer set ) on my .46 equipped 5.5lb Ultimates which have 10oz tanks.

I've landed the plane then have continued to run the engine for another 2-5 minutes on average depending on how hard I pushed the engine in uplines.

On my relatively heavy Spacewalker II with an AX, I run the default tank which is about 7-8 oz, on that I easily clock over 18 minutes on my timer. Of course the relatively bigger wings help.

14v does require more expensive batteries in this scenario though. Giving a bit more advantage to glow in terms of costs... especially the up front costs.




Yup. Longer lasting or cheaper would certainly tip the scales, and things are inexhorably moving in that direction.

Not that things are all that far off the mark, a price drop or two will remove any perceived advantage that glow has in the .40 - .50 range.

Maybe the A123's or some other technology will change all of this.


It is sorta fun to see people watch my SS EP take off and remark, "THAT's ELECTRIC? "

I'm now running my ( * cough * frail, overpriced, alternatives better, * cough ) Brio 10 with the same 3S2P packs and a smaller 30A motor, instead of the ( * cough * crap * cough * ) "recommended" Eflite setup.

It's turned into an amazing performer this way, albeit with a bit more wing loading.



Now just how do I get an electric smoke system going?

stockdaddy

Here are some tests from e-flight .46 motor. They are not the best and test was using older prolight TP packs.

http://www.e-fliterc.com/Products/De...odID=EFLM4046A

4s lipo would be 14.8volts though u do drop some voltage on WOT. If you could hold around 14 volts, that would put you a little under 60 amps for 800 watts.

I don't know how everyone normally flies though i rarely hit WOT for more than 15 seconds. Usually it is on takeoffs, going vertical and doing a high speed pass.

ELTIGRE

I never said a word about flying with Lipos !! & I charge at 5 amps!

again ( for those who havent listened) the cost is amortitized over TIME.