RE: My Hurricane 550's first Hover
The Lepton and T-rex 500 are smaller, just so you're aware. They're more like a larger 450 size heli rather than a smaller .50 like the E550 is. I'd consider the E550 a true ".30" class bird, with the Rex500 and Lepton coming somewhere in between a 450 and a .30
Posted on: 2/13/2008 5:18 PM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=7070806

RE: My Hurricane 550's first Hover
The T-rex 600 has "presence" in the air when you fly it. It's a bigger and heavier model so it feels more substantial in movement. That's not to say it can't snap around like crazy, as it certainly can and is arguably one of the better 3D machines out there since it's a perfect balance between stability and performance, but it requires a significantly more expensive set of components to get that sort of performance out of it, whereas the EP550 can achieve similar levels of performance with fairly mid-range equipment due to how light it is. Which is "better" is a matter of personal opinion. In terms of power to weight, the EP550 probably has the 600 beat by virtue of its size/weight, and with the right motor/battery setup you could probably get absolutely insane performance out of the EP550 that would make the rex-600 look tame. But, at the same time, a t-rex 450 or smaller will be even more insanely overpowered than a high powered EP550. It tends to scale like that in my experience, the smaller the models get, as their weight drops off drastically but power output can still be ridiculously high in comparison. Naturally, though you gain more and more impressive power to weight ratios with the smaller models, they also start to become twitchy and fiddly. Some guys like their model to climb 100 ft in half a second, some don't. There are some trade offs going to larger machines in terms of aggressiveness, but at the same time you get some very nice benefits, rotary stability being one of the big ones, and visibility being the other. I find the EP550 to be a perfect mix between the 600 and 450 class. It's got the aggressive authority of the small models but still instills that slight feeling of mass that makes 600 models often feel locked in and "right". If I had to choose between the two, I wouldn't. ;). I'd keep both and fly whichever one happens to strike my mood at the time. All things being equal though, the EP550 is definitely a cheaper machine to run and you'll get more flight time with it if you're learning since batteries aren't nearly as expensive.
Posted on: 2/6/2008 10:18 PM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=7036256

RE: I want a 15 size heli, whats good out there?
You might want to have a look at the Century Hawk Pro .30. It's pretty much in the price range you're looking for and is an excellent learning machine if nitro is a route you want to do. That said, there's no real good reason to get a .15 size (nitro) helicopter unless you simply wish to fly nitro. They have poor power to weight and generally fly like dogs. There's a reason very few companies make them ;). If you want something in the .15 size range, go for a 450 electric, there's no shortage of them online and you shouldn't have any trouble finding one in your price range. They're lighter and perform significantly better.
Posted on: 1/25/2008 3:56 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6968808

RE: Lead acid batteries charge ?
Most lead acid batteries work best with low charge currents. 300 - 600 mA is about the norm.
Posted on: 1/23/2008 12:25 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6956228

RE: 16c Battery Too Tame?
[quote]ORIGINAL: oly_rcer hi gary i'm using 15c on my rex they seem to be okay so far but i havent done much.c ratings dont affect output voltage so you will still have same headspeed just that more c's =more runtime.someone correct me if i'm wrong but you should be okay wiyth the 16c as for the adaptor try helidirect think i saw a few there oly [/quote] The C Rating determines the cells maximum continuous discharge capability. A higher C rating means the battery can be discharged at a higher current rate without damage to the battery. However, if your model is exceeding the batteries rated C rating, then you WILL see lower voltage as the voltage will sag as the cells are unable to deliver the current being asked of them. At this point the cells will begin to heat up noticeably and if you keep pushing the battery, it will eventually puff, like barracuda said. The C rating also effects voltage depending on the battery quality, a 15C battery from one manufacturer will likely hold voltage under 15C load better than the same battery from another manufacturer. So even though both batteries can safely give 15C (without damage) one will perform significantly better than the other.
Posted on: 1/20/2008 10:30 AM by Author "credence" in the forum "T-Rex heli"
http://www.rcuniverse.com/forum/fb.asp?m=6937996

RE: Batteries for TREX 500
Certain batteries, like the electrifly packs, have their own built in protection circuit, and so have dedicated leads, one for charging one for discharging. I'm not sure what would happen on these batteries if you tried to charge through the discharge plug, but it probably wouldn't be good, and they say as much in the instructions.
Posted on: 1/11/2008 4:02 PM by Author "credence" in the forum "T-Rex heli"
http://www.rcuniverse.com/forum/fb.asp?m=6891207

RE: How do you DISPOSE of a Lipo pack?
Salt water only neutralizes a lipo if the interior of the cell is exposed to it. Simply placing the batteries into a bucket of salt water will only corrode and eventually dissolve the tabs on the cells, so that the pack shows 0 volts when in reality nothing has been done to the cell structure and the cells indeed still carry a charge and so are dangerous. To dispose of a lithium battery all you need to do is apply a small load, such as a light bulb, and allow it to completely drain the battery to 0.0 volts. At this point the pack should no longer pose a fire hazard and so is safe to dispose of. Lipo's are only dangerous when they have a charge. This of course does not mean it's a good idea to just chuck the battery in the garbage as it still contains chemicals and lithium salts. Like any battery, it should not just be chucked in the trash, but this is a moot point now-a days as i'm sure the landfills are full of them anyways. At any rate, if you really want to neutralize the cells, you first need to fully discharge the battery, you then need to split each cell in the pack so that salt-water may enter it. This will then fully neutralize the cells in the pack. Many suggest draining the pack and then taking a small exacto blade along the sides of the cells to split the aluminum casing to allow the salt water to enter. Personally, I don't think this is necessary and it's potentially risky, simply draining the packs should be enough to at least make the cells fire-safe and so safe enough to put into the regular garbage. Thermal run-away only happens if there's stored energy. No energy = no fire :).
Posted on: 1/1/2008 10:24 PM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=6839420

RE: Is nitro worth the trouble?
For larger machines, it can be cheaper (up front) than electric. You also get the benefit of refuel and fly convenience instead of waiting for batteries to charge so it can be better for learning and advancing your skil. That said, performance wise, a good electric machine will out perform a nitro by a fairly wide margin. Which route you go depends on personal preference. Nitro machines still offer excellent performance, but there is a different learning curve involved. You'll need to learn about engine tuning and maintenance if you go nitro :). They're both good choices, just go with whatever you're more comfortable with.
Posted on: 1/1/2008 1:39 AM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6835001

RE: Why do they call it a 450? (strange question)
[quote]ORIGINAL: ct420 I think the '450' also came about, because it is simply 'a little bit bigger than 400'. Before the T-REX450 came out, electric 400 helis like the Shogun dominated the market. When align released the bigger T-REX, they called it a 450 as a comparision to these 400 helis that were out at the time... I's a pretty arbitrary number for reasons others have pointed out. Blade size makes more sense to me also. [/quote] I suspect marketing probably has something to do with it as well. The general uneducated buyer will see "400 vs 450" and think to them self, well, 450 is higher than 400, so it must be better! [:-]
Posted on: 12/31/2007 6:03 PM by Author "credence" in the forum "T-Rex heli"
http://www.rcuniverse.com/forum/fb.asp?m=6833064

RE: Why do they call it a 450? (strange question)
Generally refers to the motor size/class. They're referred to as "400" size helicopters because they use speed 400 class motors, a naming convention that was started I think by graupner with brushed motors way back. It doesn't really apply anymore with brushless motors but electric heli companies persist on using the naming system anyways. The same as above holds true for 300, 500 and 600 classed models, but like I said, it's a silly naming system that doesn't really tell you anything about the motors anymore or even really about the models size, the T-rex 500 being a good example of this. Typically "500" class machines are close in size to a .30 size nitro helicopter. In reality, the T-rex 500 is actually smaller with a smaller blade of only 425mm, not 500mm. Personally I think a better way to class the helicopters would be by blade length. 325 for the micros, 425 - 450 for the new small to mid size models like the T-Rex 500 or Hirobo Lepton, 500-550 for the mid sized electrics, 600 - 620 for the larger ones, and 700+ for the largest. As far as nitro machines, the .25 .30 .50 represents engine size in terms of displacement in I believe cubic inches. Basically it's just the size of the engine used in the model, which is then used to classify model size as is currently done with the electrics. The difference is that there is no wild difference in power and size between one .50 size engine and another. Some might be a little better, or hold head speed better under torque depending on the quality of their build, but they're not like an electric motor which can produce wildly different power output from the exact same can size depending on winds, loading, voltage used, etc. It's for this reason that nitro planes and helis typically classify models by engine size, because you know that if you stick a .30 sized engine into a model designed around a .30 sized engine, that model is going to fly, regardless of the make of engine (usually, anyways ;)). It's a good system and while I understand why the electric market hasn't been able to adopt a similar naming scheme, it's still annoying :). Hope that helps.
Posted on: 12/31/2007 12:16 PM by Author "credence" in the forum "T-Rex heli"
http://www.rcuniverse.com/forum/fb.asp?m=6831566

RE: PC Power Supply
PC Power supplies have huge differences in output ratings. Any produced within the last 5 years though would probably be more than enough to power a charger. You need to look at the side or bottom of the power supply and the label they put on it. Typically, they'll show you the 3 volt, 5 volt and 12 volt output rails, and how much amperage is dedicated to each. The 12V is the one you're interested in, and the single rail should be over 7 amps preferably which shouldn't be too hard to find. If you're charging very large batteries, then you need more of course. I've got a bunch of power supplies laying around and most are rated to about 12-15 amps. This here should help. http://www.dream-models.com/eco/DIY-powerSupply.html Only thing i'll mention is that he's using an AT power supply, if you happen to have one that's this old then you can follow that article word for word, otherwise if your power supply is from the last decade, you'll need to look inside the main 24 pin wire output and take the green wire and connect it to one of the grounds, this is the wire used for the PSU to see the power on signal. Once you do this, you can simply use the switch on the back of the power supply to turn the unit on and off. EDIT: Also, if you're going to be working around with the inside of your power supply, I strongly suggest you leave it unplugged for awhile before messing with it. The large capacitors in there can store a pretty nasty charge for a while after the unit is powered off.
Posted on: 12/30/2007 7:15 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6825730

RE: what is the whole mechanical system in the pic called ?
Rotorhead? ;)
Posted on: 12/25/2007 8:07 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6804054

RE: Twister Skylift : Why quad rotors ??
My guess is for the added stability. The use of the contra-rotating blades might also negate some of the more sophisticated mixing electronics you need for a typical tandem heli bird. If you want one that uses single rotor setups like the real one, hirobo makes a .50 size model, and MS Composit makes a small CH46 electric variant. I believe theres another company that makes one based on the T-rex mechanics, but I can't remember the name of it now.
Posted on: 12/24/2007 1:48 AM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=6797642

RE: ESC programming card
Typically brand specific, but there are some exceptions. E.g JETI programming cards will work on JETI and Dynam controllers (and I believe a few other brands as well).
Posted on: 12/22/2007 8:13 PM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=6792566

RE: New Digs For my TREX
The one with the skull is obviously better, because the skull reminds me of pirates, and pirates are awesome. ;)
Posted on: 12/21/2007 9:33 PM by Author "credence" in the forum "T-Rex heli"
http://www.rcuniverse.com/forum/fb.asp?m=6789054

RE: T-Rex 700 Poll
Well, if they're going to call it the T-rex "700" then it would certainly be electric, otherwise they could just call it the T-Rex .90! ;) I'd take an electric any day over the nitro, a 12S lipo would definitely stretch the wallet a bit thin! [X(] EDIT: Given the option, i'd probably also go for a gas, just because, well, gas is cool and stuff :).
Posted on: 12/12/2007 10:25 PM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=6750031

RE: rpm synchronizer
Since there is always variances between even motors of the exact same make, the only real way to get two motors to operate at the exact same rpm would be to use a governor, one for each motor set up for the same rpm each. At least, it's the only device I know of that will accomplish what it is you're looking for. Theres a bunch of different governors available on the market currently, don't know how much they go for though.
Posted on: 12/12/2007 2:08 AM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6746244

RE: My Hurricane 550's first Hover
There is also the fury ion-x which is one hell of a nice machine.
Posted on: 12/10/2007 5:46 AM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=6737669

RE: My Hurricane 550's first Hover
[quote]ORIGINAL: Cyclic Hardover These 450 size don't have this particular sound but a couple years ago, some guy had a big electric and sounded just like a turbine spooling up. [/quote] If you like noisy models you might get a kick out of this. http://www.truenorthernhobbies.com/mystuff/ehawkfirstflightfeb16.avi This was the very first, untrimmed flight of a Century Hawk Pro .30 that I converted to electric power last winter. Because the hawk pro has no belts (torque tube driven tail) and uses a few different gears for power transfer, the amount of noise and gear whine the model generated during flight was pretty impressive for the models relatively small size. My EP550 is nearly silent compared to this noisy thing! Even my t-rex 600 which has more power and a larger blade area isn't as loud. [:)]
Posted on: 12/9/2007 9:52 PM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=6736582

RE: My Hurricane 550's first Hover
I've got a 550 and love it. It's an incredibly smooth machine, and even on the stock motor, with 25C 2250 packs, the model has remarkable punch similar to a 450 sized heli but with the stability of the larger birds. It really is quite a nice size! :)
Posted on: 12/9/2007 10:23 AM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=6733710

RE: Futaba Gyros cause cancer!
[quote]ORIGINAL: newto3D Ahhhh....California....the land of the Fruits and Nuts! [/quote] [:)][:)]
Posted on: 12/6/2007 9:30 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6723784

RE: Need a 3800 Watt or larger brushless outrunner
mrasmm is about spot on in regards to discharge and cycle life. It's better to buy high discharge packs and discharge them at half their rated capability as it'll result in longer life. Like i'd said before, a 20C pack discharged at 10C will last twice as long as a 10C packed discharged at 10C :). If your packs never get any more than warm to the touch after a flight, then 200 - 300 cycles with less than 10% capacity loss should be possible. The actual cycle life of a lipo is about 500 cycles, but this only applies at 1C discharge rates, and it drops proportionally the higher you discharge the pack. The absolute base voltage of a lithium cell is ~2.75 volts. The reason to discharge to 80% is that if you fully discharge the pack, you'll reach that 2.75 and in all likelihood go actually lower due to load. Most speed controllers these days come with a lithium cut off at 3.0 volts per cell, some even higher. Anyways, the point is, over-discharging a lithium cell is extremely harmful and potentially dangerous as the pack will begin to swell, and if left unchecked, will ignite. That's why 3.0/cell is used as it offers something of a "safe" zone for the cells. Note that this is 3 volts under LOAD, not 3 volts standing voltage. If you're 3 volts a cell at standing voltage then your battery has already been damaged. Because of the sheer amount of cells you'll be working with, in your case it's even more important to ensure you don't come too close to 3.0 volts/cell, as in your setup some cells will inevitably discharge deeper than the other ones for various reasons, in this case, the ones closer to the speed controller will likely discharge slightly more than the cells towards the ends of the pack as there is less resistance in wiring. It's for this reason as well that I mentioned above that you make damn sure you've got a good charger that can balance the cells individually or you'll end up with a bunch of mis-matched cells that could prove disastrous during a charging session. As for A123's i've read that their cycle life is supposed to be in the range of 1000 cycles, but I can't personally confirm this, and as with anything else, how you treat the cells will likely have a big impact on how long they last. If you always speed charge them at 3C rates their cycle life may be half that. luv2glyd, i'll have to take a look over my spec sheets for you first, but I do work directly with a lithium manufacturer overseas, I may be able to help you out with some better pricing on lithium polymer packs. I also have access to lithium manganese nickel cobalt cells that may work for your application. They're safer than lipos, have the same base voltage and come in cylindrical cell form. Only catch is they're only rated to 12C discharge. If you can keep your current draw down, they might just be the ticket for you. Also, they're quite a bit cheaper than bagged lithiums as the materials used to make them are inexpensive. See my post here on RCCanada. http://www.rccanada.ca/bb/viewtopic.php?t=35496&postdays=0&postorder=asc&start=15 Scroll down to the second last posts to see what the cells look like. The biggest capacity I can get these in is 3700 mAh if I recall correctly. You can email me directly at daniel@truenorthernhobbies.com if you want to discuss it.
Posted on: 12/5/2007 2:45 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6717310

RE: Need a 3800 Watt or larger brushless outrunner
[quote]ORIGINAL: mrasmm well the first pack would give you a total flight time of (4.4*2*80%)/167A*60min in an hour = 2.5 min which would require a 24C constant drain =) To me that sounds like a no go.... you're gona need a 60v 87Ah pack in order to give you the run time of 25 min cont @ 167A (167*25/60/80%) = 87Ah see this response to your identical thread over in the electric forum =) http://www.rcuniverse.com/forum/fb.asp?m=6697922 3.3*14 = 46.2v nominal on your second pack, to shoot for 60v, you'd need more like 18 to 19 cells in series. 6 cells in parallel would give you a capacity of 2.3*6 = 13.8Ah = 4 min @167A (13.8*80%/167A*60min) = 15C discharge rate based on the 25 min flight time of 60v @ 167A I figure you'd need a 19s38p pack of the a123's in order to match what they've got which would give you 62.7v and 87.4Ah for the pack =) for a total of 722 cells, or 121 of those 6 cell packs at 110 bucks each = $13,310 =( man that's a pricey pack. if you get a 10kw gen for your car/truck (like the ones they use for portable welding) and could manage to hook it all up, and figure 80% charge efficiency, it would take 87Ah*60v/80% = 6525w/hr's so then you take 10kw/h / 6.525kw/h and you end up with about 40 min charge time =) if you go off of a reg alternator that puts out say 50A @ 13.3v, you're looking at 665w/hr charge rate, and with that it would take nearly 10 hours to charge the pack. hopefully that number crunching helps a bit =) [b]edit[/b] you could do a 3s20p pack of the first ones and that would cost you 7800 bucks to get a 66.6v 88Ah pack, but you've have a really big liability with that many lipo's sitting around, if one decided to go you'd have an inferno. [/quote] 167A @ 60V would give him over 10 kw of power. This is way higher than what he needs. I don't even want to think about how much 88 ah of lithium cells would weigh! That said luv2glyd, just curious how you ended up at the figure of needing 3300+ watts for your setup? Are you just basing it on average ready flying weight? Or is a 3300 watt power system simply what other people are using so you know it's the right range to be shooting for?
Posted on: 12/3/2007 7:59 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6709886

RE: Need a 3800 Watt or larger brushless outrunner
He's trying to convert a powered para glider to electric. Basically a parachute with a small prop out the back to provide forward momentum, usually powered by a small gas engine. Guess you could kind of look at them as sort of a poor mans personal airplane [:)]. It's something i'd love to try if I had the money for it. Oh, and the training too, I guess! [:D]
Posted on: 12/3/2007 7:54 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6709862

RE: Need a 3800 Watt or larger brushless outrunner
Most people are pulling A123 cells from Dewalt or Makita battery packs since A123 does not sell directly to the hobby market as far as I know. A123's have 4 major benefits though over standard lithium-cobalt chemistry, first one being longer cycle life, second being high (30C+) continuous discharge rating, third, they can be speed charged at rates twice as fast as lipos, and lastly, they're made of a much safer chemical composition (lithium-nano-phosphate). Thermal runaway is almost non-existent with these cells, whereas a punctured lipo cell can be like a small hand grenade, and the higher their density, the more dangerous they become. However, there are some notable downfalls with A123's. First off is their peak charge voltage is I believe only 3.6 volts vs 4.2 with standard lipo. This means you need more cells to make up the same voltage as a standard lipo battery pack, which obviously equates to more weight. And, naturally, because they are a cylindrical cell form, they are heavier than a standard bagged lithium cell. Regardless of which chemistry you choose, connecting them to a car battery is not the best method for charging. First off, a 15 aH pack will take a huge chunk of power from your car battery. Most car batteries are I think around 50 aH for a good quality one (if i'm understanding this bizzare "reserve capacity" rating right anyways) at peak charge. Since your car battery is not likely going to be at peak charge, you don't want to be draining that much juice from your car. You may not have a problem if the car is running, but it's hard to say. I've read about guys flying larger helicopters and using their car to charge batteries only to find their car won't start when they're ready to go home! Not the best situation to find your self in. The other reason is that lithium chemistry, regardless of which one you use, requires dedicated charging hardware built specifically for it. One thing you definitely do NOT want is overcharged lithium cells, else you'll be treated to a spectacular fireworks show. I encourage you to read up very closely on the safety information of lithium batteries. It's great technology but you need to exercise a lot of caution with them as it's a fairly dangerous chemistry and NOT tolerant to negligent abuse. In your case, you'll be working with high voltage and high capacity, which means you've probably only got 2 choices for charging. One is that you find someone to design a dedicated charger for the massive bank of cells you'll be using (likely expensive). The other is that you configure the packs so that they can be separated in chunks (i.e 22 volt packs at 5000 mAh x3 or something) at which point you can use a good commercially available lithium charger, though it'll take you longer to charge all 3 banks unless you buy multiple chargers to do them all at the same time. I would suggest either purchasing an external car battery for charging (that you can then later on charge at home and then bring to the field), or just a small gas generator of some sort to power the charging equipment at the field. Given the amount of cells you'll be working with, I would strongly encourage you to read all the proper handling procedures for lithium cells as I said above. Things like minimum discharge, charge, max current draw, cell balance etc. are all really important not only for the lifetime of the battery, but to also keep that large bank of packs from igniting during use (something you DON'T want happening when they're strapped to your back and you're 2000 feet up!). Specifically, because of the amount of cells, cell balance will be extremely important, so having a charger capable of balancing the cells is an absolute requirement. The batteries will be the most critical part of your setup and you need to put serious forethought into how the setup is going to work, and work safely. Understand that you're basically trying to use commercially available hardware for an application it was never really intended for, so a large amount of the brunt work is left up to you to ensure things not only work correctly but to a safe enough degree. What you plan to do should be considered "highly experimental" considering the sourcing of the components. [:)]
Posted on: 12/3/2007 3:10 AM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6706994

RE: gyro quality
There are some segments of this hobby where going cheap you can often save a good deal of money and still get great performance. This includes items like motors, batteries and speed controllers. However, gyros are NOT one area where buying cheap works. I have never seen a cheap gyro perform even remotely close to something such as a GY401. As others have said, buy a good gyro, the differences are immense.
Posted on: 12/2/2007 11:17 AM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6703317

RE: question too long look inside please thanks
There is almost no good reason to go nitro for a 450 sized model. You'd get way more power from the electric version and flight times would be comparable if not better. I've seen a few videos of .12 and .15 nitro machines flying and thought they were pretty lack-luster in performance. A lot of noticeable head bogging during high pitch. Nothing like their bigger brothers. I've also read about the small engines having cooling issues, can't confirm this though. Of course, if you just want a model this size for the sake of having a small nitro ship you can't go wrong, especially if aggressive flying isn't your thing. Just don't expect to get the performance from it that you would get from a well set up electric because it isn't going to happen.
Posted on: 11/30/2007 4:58 AM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6694002

RE: LiPo Question
charged 3/4 of the way is best for long term storage. For any sort of decent cycle life from the batteries don't exceed 140F during use, obviously, the lower the better. 160F I believe is the max before you start getting puffing and pack damage. Most packs need to be warm anyways to deliver their full potential, just keep an eye on it. If it's getting too hot you're pulling them too hard.
Posted on: 11/29/2007 5:23 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6691588

RE: Need a 3800 Watt or larger brushless outrunner
Those look like specialty batteries. Maybe from electric car manufacturers? Can't help you, never seen cylindrical cells that big. If you want something cheaper you might want to consider having a look at A123 or eMoli cells. You'd need whole lot of them for what youd want to do but they'd probably work. Surely there must be electric para glider forums? Have you not asked around there? As for the motor, you may have some trouble with that. By design, that motor probably won't fit the type of props you're looking to use. Most large scale motors use a 6 or 8(?) bolt prop mounting system (like shown in your picture) because the amount of torque is so great. I do not know if that prop adapter would be enough with just a single nut putting pressure on such a large prop without the prop slipping under use. I can't say since i've never done anything this large, but i've seen even on giant scale models that guys use a bolted prop instead of pressure mounted one so there's probably a reason. At any rate, that motor looks to be made by the same factory as the Tower Pro motors. They're cheap but incredibly durable motors from China. I've used one in larger e-conversions and it's seen more crashes than I care to think of, and aside from having to replace the main shaft, it's lasted almost 2 years with nearly 4 crashes. Oh, and in all this time, the motor was running way out of spec too. Running a motor rated for 14 volts max at 22 volts and getting a nice 900+ watts of power from it :D. For a motor that costs $40, I can't believe it's still going!
Posted on: 11/29/2007 3:16 PM by Author "credence" in the forum "RC Helicopter General Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=6691040

RE: Maxi-Joker motor selection
Unfortunately it's not quite as simple as just doubling your voltage. By increasing your voltage you will increase your amp draw and thus the stress being placed on your batteries. (Contrary to popular belief, higher voltage does not automatically equal lower amp draw, they go up together linearly unless you alter the load being placed on the motor). It may well be you won't be able to go to a small enough pinon gear to reduce your headspeed to a point that won't draw current far beyond the batteries ability to deal it. Which means you need to increase your battery size to handle the amp draw, which places you back at sqaure one. The joker flies on 37 volt packs (10 cells). Doubled that's 74 volts. Assuming you even find a motor and controller that can handle that much power, the batteries at half the capacity won't likely handle the draw and you'll get a dozen flights before they crap out. The most powerful controller i'm currently aware of is the Kontronik Power Jazz which only does a max 63 volts peak (So only 15 cells in reality). The controller alone is $400. I don't even know of any brushless motors in that power range to fit the joker. Plettenburg does make other more powerful motors like the predator but I doubt they'll fit on the joker. http://www.icare-rc.com/plettenberg_predator.htm Even this motor won't hit your target max voltage, and the price is in the $1000 range. So, $400 controller, $1000+ motor, $1200 helicopter. This is JUST the power setup not including batteries. You can see why I suggested a gas powered model in the first place. I am a huge advocate of electric flight and I make business selling electric products, but when it comes to heavy lifting with a small scale rotary craft, it's simply cheaper in the long run and up front to use a gasoline powered machine. Now, that said, you do have some wiggle room if you only need to increase your lifting capacity to say 8 lbs. You can INCREASE your voltage (not double) within reason and use a smaller pininon gear, and also try for a multi-bladed head to load the motor further. That may get you the extra lift you need, but at this point it's a lot of "what ifs" so I can't really comment. I don't know if anyone has done this with a .90 size model. You also need to keep in mind structural stability. You can only increase the blade size and/or headspeed so much before the model becomes unsafe to fly. Too high a headspeed and the blade grips will shear. Too big blades and they'll hit the boom or tail blades. A multi-bladed setup might solve this, but be forewarned that multi-blade rotorheads are much more difficult to control since they don't have flybars. I'd suggest trying a flybarless setup on a smaller less expensive model before risking a big expensive one. edit: I just noticed I had linked to the bergen industrial twin which is $6000 when I was looking at the observer EB price which is $3300. The EB has an 8 lb useful lifting capacity I now see. I had two tabs open before when I was looking at them and must of got them mixed up. [:)] I see the twin is way out of your price range. Like I said above, you might be able to get 8 or 10 lbs from the electric model but not the way you originally wanted to do it, it'll probably cost you more than the gas machine in the long run. It doesn't even need to be a bergen machine, I merely chose them since they make machines designed specifically for carrying large camera payloads. They come with full pan and tilt mounts on the frame and everything. Regards,
Posted on: 11/28/2007 4:16 PM by Author "credence" in the forum "Electric RC Helis"
http://www.rcuniverse.com/forum/fb.asp?m=6686323