gwright
Senior Heliman
Location: Melbourne, Fl
| It's not as cut and dry as Z1135 makes it sound. As an aside,..i always wonder why people find a need to hide behind ficticious names on these forums,.. "Z1135" for instance,..but I digress. I still fly a fury 91, but I fly mostly electric now. The fury with 91 gives me 8 to 10 minutes per tank,..say average 9 minutes. Most people would agree that a "good day" is a gallon of fuel burnt,..that equates to just under 8 tanks,.. so about 70 minutes actual flight time. I re-set the cumulative timer on my transmitter now when I go to the field, and when I go with electrics only (planes and heli's), I normally go just over 2 hours of total flight time (logo 10, logo 20, E3D, hotliner, and 30-cell Katana is the normal stuff I take to the field if only taking electrics). I plug 2 10-cell packs in series and charge on each supernova, takes about 45 minutes to get 2 10-cell 3000mah packs peaked. I have two supernova's, so that's really 4 packs,..so about 11 minutes per pack if you wanted to "cost account" the time like that. My new schulze 636 charger that I'm falling in love with, gets my 30-cell Katana pack up in 24 minutes. I can plug 3 10-cells up to it and charge for 3 flights with a 10-cell ship, or 3 12-cell packs for the logo 10. My logo 10 goes anywere from about 5 minutes to 8 minutes depending on what flight mode (rpm) I'm using, average about 6 minutes, with power to weight a bit better than a .30 glow heli. My logo 20 can go 3.5 minutes of ballistic performance, or 6 minutes of OK (about like a raptor 30 power to weight ratio) at a lower rpm flight mode. In the 3.5 minute flight mode I'm turning over 2K on the head with 12 degrees of pitch, and that's on 600mm blades. It does load down to about 2K with full pitch,..i.e. power to weight is like an 80 or 91 glow machine in that flight mode,..maybe a bit better. most of my electrics fly 70 to 80% as long per flight as a glow aircraft, about 60% for the helis (the hotliner and E3D surpass most glows in both performance and duration), however, i get over double the number of flights per session at the field that I did when only flying glow. one recent saturday, i was at the field 6 hours (8am till 2pm) and flew 27 flights electric only, totalling 2 hours, 21 minutes, so about 2 gallons and another tank worth of flying in the 91 would be the comparison. You can get much BETTER power from an electric than a glow, but at the expense of very short runtimes,..or you can get the same runtimes with less power. An electric can use-up all the "fuel tank" very quickly, whereas a glow can only burn the fuel at one rate always, hence the wide discrepancies in flight times due to flying style and such. There are battery technologies that are emerging that could possibly make glow obsolete. they are expensive at the moment, but decreasing in price pretty quickly. I like to be on the forefront of technology, and electrics, in my opinion, will be the "standard" in the future, so I'm going through the learning curves now to be ahead of the game. There are allready some people using lithium polymers to get 20 to 25 minute flights on my E3D kits,..which have equal or better performance than most glow-powered 3D planes. If my math is correct I should be able to get 20 to 30 minute flight times with my logo 20 using those cells, with the performance I'm getting on my 3.5 minute setup right now. the cost is coming down, but it's not at the threshold yet for me to go that route. On another forefront, there is a battery technology just emerging that has roughly 5 times the energy density of those cells, so they could prove to create a situation where you charge up, and fly 8 or 10 "normal 10-minute flights" at the field, without ever re-charging,.. and have up to double the power we get with glow, or,.. change the setup and get the equivalent of 4 or 5 horsepower in a 30 size machine for one flight. We're only at the tip of the technology right now, and it's growing exponentially. the power is available to surpass glow,.. just not with good runtimes. These battery technologies that are emerging now could be the element that not only matches e-flight to glow, but pushes it well past glow power. With the ability to use all you're energy very quickly, you could easily double the power we have with glow right now,.. and with higher energy-density "fuel", it could mean higher flight times than glow. I prefer to look to the future rather than clinging to the past. Glow engine power comes from fuel,..the engine is just a converter (same with electric), and the best glow engines were 21 to 23 percent efficient a few years ago,.. they've made huge improvements and are now around 25~26 percent efficient (example would be 61SFN to YS80 here). Electric power systems have went from 55%~60% to 88%~93%,.. a much greater increase in the same amount of time. As always though, the "fuel" (energy density of the batteries) is the weak link. They have went from 1V at 1200mah to 1V 3300mah for a 60 gram cell in a few years, that's 72 watt minutes for 60 grams, or 1.2 watt minutes per gram, up to 3.3 watt minutes per gram, a tripling of power. the lith polymers are roughly 27 watt minutes per gram,.. about an 8-fold increase, so for the same weight, that 3.5 minute logo 20 with ballistic power would be around 30 minutes flight time. The even newer technology I mentioned looks like it will almost double the lith polymers in energy density, and is capable of 50C charge rates (one minute, 2 seconds to fully charge, although we'll never see that, since we'd have to plug into a powerplant to deliver that sort of current,.. we'll probably see sub-10 minute charging scenarios simply due to the limited power you can extract from 12-volt lead acid supply's at the field).
sorry for the long diatribe but i was rather offended when someone attacked another technology simply due to their own ignorance of that technology.
Gary Wright |
