stopped at the bar for 2 drinks after work and a woman told me that Jason might fly an electric pattern plane at the worlds? could this be true?

I heard that he is flying Angel Shadows again this year as he has ordered 2 new ones from Russia. also since he flew one at the team trials, I wouldn't think that he would change models this late before the worlds.

Plus I'd say this wouldn't be too good for his engine sponser, OS.
(He is still with them isn't he?)

Robert, why would he need an OS sponsorship, If he has an electric motor companys sponsorship?

I think I saw somewhere, Jason was comenting on his experiences (peformance wise) with the 3M 170.

Can't remember the page, but I pretty certain it was a US based page, that had a comparison of engines RPM wise.

Anyhow, should be interesting to see if he has gone electric, It definantly seems to be the future of pattern flying.

At the SEFF show Jason said that he would fly an electric plane at the Worlds if it was ready. It is currently being built

Can they just change sponsers like that? Well I suppose with Chip and PL its possible. My bad.

The current issue of Quiet Flyer has a picture of Jason with an electric powered pattern plane called an Akro 2. It is powered by Thunderpower lithium polymer cells and a Hacker brushless motor. The weight is reported at 9.5 lbs. Maybe this is the plane you have heard of?

The Akro 2 was flown by Jason at the SEFF show in June. The model was a prototype from Aero-models. Don't know if this is Jason's plane or if it will be a different model.

the acro is a lorenz plane, dunno if they make it anymore, can't find it on the site. 3 of their "rhapsody" planes were just picked up for Jason at the worlds. If things work out, he'll be flying them with Hacker C50 acro motors and thunder power lithium cells. the rhapsody's are "current" style planes for pattern and/or 3D (they have a specific 3D version but that's not what he got). With the lithiums and the C50 acro's, power is somewhere between 140 and 170 glow, total weight should be just under 10 lbs (they're a touch lighter than the acro-2's) and flight time is close to 1/2 hour per charge. i think the website witht he rhapsody's is www.f3alorenz.de

Wow that should be quite a setup!!!!!!!!!!!!
What is the average weight of a WC level plane all fueled up?
What is a lithium battery pack such as that worth?
Lifespan?

I still believe this is the way F3A is going to go.

All this belly-aching and talk of Gas power is just a cover up for the electrics. Now you won't even have to buy Gas.

I don't think I want to know how much that set-up is going to be worth including all you special chargers for those type of cells.

It'll be a lot less than your average F3A pilot spends in a year on fuel. In fact, those of you flying DZ's or EFI's probably spent more on your installation.

The funny thing is that, they might be a bit pricy, especially the big ThunderPower LiPo packs needed for F3A (around $400-$600 depending on final configuration), but the cost to "refuel" them is oh so CHEEP.

Compare the battery/motor cost to a YS DZ140 (and dozens and dozens of gallons of fuel) and it doesn't look so bad.

I saw Jason fly the Acro 2 at SEFF. It wasn't underpowered at ALL by anyone's reckoning. In fact, a lot of folks just stared, slack-jawed, in amazement.

Rick.

I have no experience with anything other than NiCads at the moment, so bare with me if these are stupid questions.

How many cycles does the ThunderPower LiPo pack last for?

Do the LiPo batterys get a memory, or reduced capacity as they get older?

What sort of charger is used to charge and monitor the packs condition?

What is the throttle response like in this setup?

Is motor and or battery cooling a problem?

Db readings?

Thankyou,
Cameron McDonald

No one is really sure about how long they will last under current levels we demand from them. I would expect similar life to NiCD and NiMh cells, 1000 Cycles.

They have no memory. Capacity with diminish with time but currently you have enought power to fly 30 min plus so you could have a 50% reduction and still have plenty of power to complete a sequence.

You use a constant voltage/conastant current power supply to charge the cells. You set up packs of 3 3.7v cells (11.1v nominal) and charge them with a 12v power supply at ~8amps. 8amps sounds like a lot but these are 7800Mah packs and they still take quite a while to charge. As the pack reaches a full charge you will see the amps drop off. The pack is fully charge when the amps hit 0.0. You then gang these packs to arrive at the final voltage you want to sent to the motor.

Beyond Instant! No engine will ever be able to deliver the throttle response of an electric motor. The torque peak on an electric motor occurs at 0rpm once energy is applied.

Its not a problem its just something you have to plan for. Cooling the motor is no sweat. Just use the same openings in the cowl you would use for you I.C. engines. The only thing that takes planning is cooling the battery. All you need is airflow. An intake in front of the cells and a larger exit to vent the expanded air and you are set. On some designs the cells would probably fit in the pipe tunnel. In that case you could use the exixting pipe cooling vents.

lipo packs don't tend to get hot like nimh/nicad, so battery cooling isn't a big factor in designing the aircraft. Motor cooling, however, is another story. Motors that never got hot with 8 to 10 minute flights tend to get rather "tasty" with 30 minute flights, so more motor cooling should be planned for, or, more efficient motors like the hacker C50's. Talked with Sean this morning (importer of hacker motors). They've flown the rhapsody's and performance is good, but they are a couple ounces over the weight limit. Currently have large rx packs and big servos everywhere, so that little "problem" will be recitifed shortly. The 10-cell lipo setup is working well, spinning a 20X13 prop in the mid 6K range. The only negative is that speed is a bit high, so they might actually have to prop down and reduce power a bit .

Gary - I saw you had the E3DXL at SEFF. I remember reading how you wanted to do an electric pattern plane after you lost your Lexx. Have you looked into that anymore?

How many LiPo packs would you need to fly 6 flights/day? How long would it take to charge a LiPo pack large enough for F3A flying?

I believe this is avideo of the plane in question.http://www.rccraze.com/newpattern.mpg

Would take a lot, but you have to classify exactly what a single flight is. With glow, you're looking at 9 to 10 minutes, whereas witht he li poly's you get about 1/2 hour flight time with an electric,..i.e. 3 times a glow. It takes a bit over an hour to charge. You charge constant current at 1C rate till you reach 4.2V per cell, then hold that voltage and start dropping current till current reaches zero. They reach 4.2V per cell in about 45~50 minutes and they're about 95% charged at that point. It takes another 1/2 hour to 45 minutes with the current tapering off to get the other 5% in. I generally fly when they reach 4.2V per cell. I figure I'm not going to fly 1/2 hour continuously, but more like 10~12 minutes like anyone else (I've actually sat at our field on sundays and timed people, other than the few exceptions, average flight time is 8 minutes with the glow guys and we have a very large club, 30~40 guys there on a sunday, so it's a good representation). li-poly charge times are lengthy, but what I've found is that I normally fly a 10~12 minute flight, sometimes extending that to 15 minutes (timer start at takeoff roll and stop on wheels down). I can plug in to the charger and "top off" the pack in 30 minutes, but fly whenever I really want to cause there's another 15 minutes or so worth of time in the pack after I land,..i.e. I don't really have to wait on charge to finish. li poly's are different from nicad or nimh. There is no memory, and they actually prefer to be charged to 90~95 percent, then discharged partially (not all the way down, can't go below 2.5V per cell or damage occurrs), so they actually suit the normal style of flying far better than nicad/nimh. They can also be charged, and sit for literally weeks before flown, with no noticable degredation in performance,..i.e., they don't have to be flown "hot" off the charger. I fly quite a few 10-cell planes (or 3series/4 parallel 8200 thunder power lipo's,.. they're same size as 40-size glow planes), and I keep 3 pakcs charged. If I want to go fly after work for instance, I always have 3 packs ready (hour and a half of flight time, about 7 to 9 equiv. glow flights). sometimes I don't even take a charger to the field since I have plenty of flight time available with those packs. for F3A, you would use 9S4P, or 10S4P (10 series, 4 parallel is what's in the rhapsodies for Jason), so that would be 30 minutes of flight time roughly,.. available without charging, or 3 practice patterns per charge.Since the normal routine at the field is to fly, then BS with the guys 15~20 minutes,..then repeat, you can actually charge during the normal downtimes and fly as much, or more, than glow. Sorry for the long dissertaion,..but with the long flights now available with electric compared to glow, you can't really compare in number of flights flown since electric flight time is about 3 times glow flight time per charge/fueling.

in this configuration being discussed is there a separate "flight pack" for the servos and Rx? or does it run through a BEC like the little-er ones do? sorry, my experience with electric is only with the little parkfliers

thanks

Hubb

You can do it either way. They're using a small reciever pack in Jason's planes. The only BEC option is with an ultimate BEC (U-BEC by www.koolflightsystems.com). The U-BEC, however, is rated for 5 amps, and so with a "normal" pattern setup (digital servos everywhere) you'd be above that, so a seperate small reciever battery is really the way to go to not risk anything. BEC's are reliable, I use the U-BEC's in most everything, but there is no BEC option for setups drawing lots of current (several digital servos). I'm using a U-BEC even in my 88" span 3D electric (some videos in this report http://www.rcgroups.com/articles/ezo.../seff/seff.htm), but it has 5 non-digital servos in it.

Gwright,

Thank you for the long response (appreciated). I guess I am a little different than most I have my timer set for 18 minutes (start just before takeoff) and can fly in the low 20 minutes. I usually fly an F3A routine, take a mental break and work on a few maneuvers, then fly the routine again, so 30 minutes available is not too different than my current setup (I probably have about 23 minutes if I fly the tank empty). I also try to practice 5-6 flights per day. Since the batteries can be charged in 1 hour, then I believe I would plan to have about 3 packs, flying and charging continuously to always have a pack available.

How long should I wait before charging a pack that just finished flying?

How about the motor, how long should you wait between flights to let the motor cool if I were to fly 20 minutes per flight?

Electric pattern sounds very interesting! I know Dave Von Linsowe tried it a few years ago with a USA Star, but the battery technology and probably the motor technology may now make it a much more viable option.

Gary,

How many Lipo chargers do you use to keep your hangar of electric planes (the ones you fly on a regular basis) ready to go?

Wiz

electric flight....it is manifest destiny!

Truly, though, LiPo's are changing everything.