Hello, I thought it was time I through my hat into the ring of electric control line flying.  I first began flying control line airplanes in 1951.  I flew from 1951 thru 1957 and then again for a short time in the 60s and again for a short time in the 80s until I again started about two years ago.  I have only flown in three contests in my life.  A WAM contest when I was 12 years old and the Golden State Stunt Championships in 2008 and 2009 and had the pleasure of finishing first in the Beginning Stunt class in 2009.  I have been experimenting with electric for about a month now.  I read this forum and asked questions before I bought equipment.  I took an old frayed Brodack Pathfinder ARF to use as my test platform.  I ended up starting with a Flyermate 1250W, 700KV, 80A motor (I wanted to get a Turnigy SK42-50-650 but they were unavailable at the time), a Flyermate 4500MAH, 5S, 20C battery, a Castle ICE75 ESC and a Will Hubin FM-2a timer.  This package came out a bit on the heavy side between 70 to 72 ounces (my digital fish scale just won't settle down for an exact reading).  I have been experimenting with different props and rpm settings with varing results.  I have concluded at this point that my motor is probably a bit to big and power hungry.  There does seem to be a huge power use difference in props.  I found that the APC electric props seem to be much less power hungry than conventional props.  I am very pleased at this point with the performance of my electric but would like to achieve a longer flight time.  It does seem to me that the pusher props do have more line tension above 45 degrees than tractor props.  Hobby King has the SK42-50 motor back in stock so I orderd one to try and see if I can get the desired performance while using a little less power and weight.  I also ordered a TR 35-38C-800 (Hobby King's equivalent to an AXI 28-26-12) to try as well but I'm afraid this motor may be to small for larger airplanes.  I hope to build a Brodack T-Rex when I perfect my electric package.  The T-Rex seems to be ideal for electric use because of its motor mount design and the large amount of internal space for electronics and a battery.

I want to express my thanks and gratitude to folks such as Paul Walker, Rudy Taube and Will Hubin for their assistance and patience with my steep learing curve questions.  Their help and kind consideration has been invaluable in helping me along the path to sucessful electric control line flight.

Roger Anderson
PCFlyers, Fresno, CA

I concur, WELCOME Roger!

Look down the list a ways, Bob Branch did a build thread on the T-Rex converted to AXI 2826 power - I have seen it fly and can affirm that it is a great package.

While developing the new power systems for Brodak I used a Arrowind 2832 in a Pathfinder with 4Sx3600 packs, RTF weight of 61 oz.  That motor is actually 6mm longer (and more powerful) than the AXI 2826 that works so well in T-Rex, it proved to be way more than was needed.  I since converted the PF to an Arrowind 2820 (same size as Alan suggested for the AXI) and will fit it up with 4Sx3300 packs. - all while netting a tidy weight savings.

Unfortunately I got it converted just before the snow started (I know its hard to explain SNOW to a left coaster!  ) so the PF is waiting for a warm-up trend...

Don't forget to check out the "List your Set-ups" thread at the top of this forum, Will DeMauro has an excellent SV-11 (I think it is roughly the size of T-Rex also) using a Scorpion 3026 (I think) which is equivalent to the AXI 2826.

Hi Dennis,

If I remember correctly, Archey recommended the Turnegy SK42-50, ICE50 ESC and Will Hurbin timer with a 3300 5x battery for use in Strega size planes.  Isn't the T-rex in this category?

Thanks,

Roger

Thanks Dennis and Alan for your inputs.  I guess the problem I have is trying to convert equivelent power from nitro to electric.  For example;  an OS 46 is rated at 1.2 HP at a given rpm,  in electric terms, this would equal almost 900 watts.  Engines usually installed in the T-rex are from 61 to 75 size with rated HP from around 1.6 to 2.0 which would translate to about 1200 watts to 1500 watts.  That is why I thought the AXI 2826 would fit the category of a 35 to 46 but not as much as the 60 to 75.  Am I calculating incorrectly?

Thanks again,

Roger

Roger,
I guess I don't really watch the IC horsepower, because 1) it isn't clear to me that we even run those engines in CL that hard, and 2) we run thin large diameter props which I believe deliver the same thrust with less input power than the typical glow engine prop.

What is important is that we need the same thrust and power output from the prop as you get from a glow setup, but not necessarily the same power input.

But in the absence of any other way to compare, it (comparing power outputs) is a reasonable place to start. But now we have a fair number of examples which really do seem to work well.  

Roger

A pathfinder size ship will power nicely with an Axi 2826/12 on 4 cells with a 12X6 prop. 3000 to 3700 mah packs will be nice and conservative.

I am flying the T_Rex with an axi 2826/12. I flew it at first with 4S package (20S 3000 mah) but was running too high power for good governor use and am now flying it on 5S 3000 mah pack. Dennis has seen it fly both ways but at its size the 5S works less hard. Its 63 oz with the 5S pack.

bob branch

Roger

I am current turning an APC 12X6 E pusher prop. Once I get the airframe completely trimmed I will do some work with the Adamisin low pitch prop. But I have a large database of experience with the powerplant with the 12X6E and EP and it flies the plane very well. Still very early on in development though, especially on 5S. No way near far enough along to say that is where I will end up.

bob branch

Roger,

<snip>...
....  Why 6S??  Well, I want to break the 2000 mah pack barrier and the only way to do that is to increase voltage and reduce current. 
.....<snip>

Archie Adamisin
Muncie, Indiana     

Archie,
As someone who has more or less stuck with 2100mAHr cells, I do mention that they seem to represent a cell size that maximizes mAHr/oz. That's one reason I have stuck with them.

I have both 3s and 4s packs. I have run the 3s packs in parallel for the early flights for both my Nobler and Vector. I knew that 6 of these cells were plenty of energy, but wasn't sure how much I needed.

At the time I went parallel simply because my motor kV (~1000kV) matched that cell count. Also the Phoenix35 ESC I had was somewhat vague about whether it would work with 6s or not (one thing said yes, the other said 5s). But anyway, energy is energy, no matter how you passively arrange the cells.

Anyway, with these packs I could go 3s2p4200, 4s2p4200, 6s2100, 7s2100, or even 8s2100--but anything over 6s would require a HV ESC, or the non-lite version of the ICE (although I think the restriction in the ICE is mainly for the BEC, I have heard the firmware for the lite won't let you run over a 6s). I might mention that all packs are the same pack assembler (FMA) and cell type.

Alan,

Being able to use the smaller capacity also give the options to use A123's without running them in parallel.  The reduced voltage would require some thought as to cell count, but I know that Igor was very successfull with them.  I like the stability and capabilities of the A123 packs and know that with all the demand for them right now in other markets, they will grow to be more affordable and hopefully lighter.  

This is going to be a good year!!

Archie Adamisin
Muncie, Indiana

So you're shooting to use the smaller 1400mAHr A123 cells ? ? ?. I forget the capacity of the larger A123 cells--was it 2000 or 2200mAHr?


modified to put spaces between the three "?" Didn't mean to put the frowning smiley ( ) in!

I flew my electric powered Pathfinder again yesterday.   I made 2 - two minute flights for a total of four minutes flight time using 2145 MAH from my 4500 MAH battery.  I was using an APC 12x6 EP prop set at 9510 rpm.  Lap times were from 4.9 to 5.1 on 64' eye to eye lines.  Flying characteristics at these settings was very good.  I calculate that I could now fly a full 6-1/2 minute flight at these settings and stay within the 80% battery capacity rule on my 4500 MAH battery.  I am looking forward to receiving the motors that I have on order and continuing to expand my electric control line flying experiences.

Roger

You will find that probably around 5 min 30 sec flight time will get in the full pattern with laps to spare. Not much need to run 6:30.

bob

Yee haw!  Sounds like you are making serious progress there.

With the 12x6 we flew the Pathfinder at 9000 RPM to generate 5.3-5.4 lap times on .018 x 66' lines.  It would use around 2600 mah, over a 5:45 flight time.  All a long an windy way of saying - YOU ARE ON TRACK.

* Thus per Alan's post you can probably slow down quite a bit - the only other diference is that my PF was flying at 61 oz, and sounds like yours is heavier - you might not be able to go all the way down to 9000 RPM, unless...

* Did not see it in your post - if you switch to a 12x6 PUSHER your line tension will improve which will also enable you to slow down a little.  Slower is usually easier to fly, and of course saves a LOT of electrons.

* At 4.9 to 5.1 lap times you can finish the pattern in under 5 minutes - thus like Bob said, you can target your flight timer for much less than 6:30!


I am SOOOO jealous of you folks who can fly in January! 

Great Zot that's it!  I can make SNOW ANGELS while I fly! 

Sorry, this ain't flyin weather, it is good for CURLING tho.   

Hi guys, thanks for the input but when I flew the Pathfinder last Tuesday at 9270 rpm on an APC 12x6 e (not a pusher) prop the flying lines got a bit loose on the overheads.  No one brought out their stop watches last Tuesday so we did not get lap times on the 9270 rpm flights.  The local hobby shop just got the APC 12x6 ep in Saturday on special order for me so I have not flown that prop before yesterday.  My Pathfinder is quite heavy at 70 to 72 ounces, so until I get some lighter motors and batteries I don't think I will be able to slow the lap times down too much.  I will probably set my timer up for about 5-1/2 minute flights and see how that does next.  I really can't do much more that that at this point until I receive the motors that I have on order.  I ordered the one each of thed Turnegy 35-48-800, 900 & 1100 kv motors to try.  It should be a lot of fun and will keep me busy for awhile.

Alan,

Weight of my electrical componets is as follows:

Motor    -         261g    or    9.21 oz
Battery  -         550g    or  19.4  oz
ESC      -           56.7g  or    2    oz
Timer    -                             .3 oz

If I change the motor to a Turnegy 35-48 I will reduce the weight by 3 oz and if I reduce the battery to a 3000 MAH, 5s, I can reduce the weight another 5 oz.  Those two changes would bring the total weight of my plane down to 62 to 64 oz.

Roger,

The 35-48-900 will be the one that will performs best in my opinion.  I have one of the 35-48-1100's and it is a hoss, but it will draw some current on a 12 x 6 prop.  The 900Kv will be happy with either the APC 12 x 6 or even the APC 13 x 4.5P that my uncle Dennis had made.  I would highly suggest that you try the pusher as it really helps out with the torque effect that we experienced first hand with Uncle Dennis' Pathfinder.  The pusher prop made significant improvements in vertical and overhead manuevers.  He flies his on 66' of 0.018" lins with no issues on a very similar motor to the 35-48 motor platform. 

Note that all the Turnigy SK 35-48 motors that you have purchased will work.  The standout will be the 900Kv as it is the best fit for the job.  The 1100 Kv is a high rpm motor and the 800Kv is a grunter.  Depending on line length and desired lap speed you should be able to tell which motor is best suited for you.

Archie Adamisin
Muncie, Indiana 

Sorry guys, but I forgot to mention that I also ordered a Castle ICE50 Lite ESC that will reduce my weight by another ounce.

I fly 6 cells of 2.3Ah A123. Model is 1750g heavy (62oz) on APCE12x6 and AXI 2826/13 (or /12 if the battery is fresh). Flight time is 5minutes and uses ~95% of its capacity. I charge BACK 2000-2100mAh.

There are also smaller cells with the same properties, just the capacity is 1.1Ah. But I think 3 cells of 2.3Ah are lighter compared to 6cells of 1.1Ah, so I thonk it is better to use 3s 2.3Ah.

Hi Guys,

I flew my first long flight on the electric Pathfinder last Friday.  For test purposes, I set the Hubin FM-2a timer for maximum time.  The flight lasted 6 minutes and 36 seconds by my brother's stop watch.  Total MAH used was less than 3000 (sorry but I forgot to write down the mah and at my age, I'm lucky if I can remember my name at any given time).  RPM ranged from a little over 9300 to 9510 rpm.  Highest amps drawn were between 36 to 37 amps.  Prop used was an APC 12x6 electric pusher.  Performance was very good.  I must say that I was pleasantly supprised that the power consumption was much better when doing a long run than when doing two short runs. 

I am now going to begin to put together a Brodak T-Rex ARF that will be electric powered.  I will be using a Castle ICE50 LITE ESC, a Will Hubin FM-2a timer and the motor and battery are yet to be determined.

Four whole days of rain.  Brings a tear to my eye. 

Hooray!  We got to play today!  Here is todays results for the electric Pathfinder:  Setup:  Flyermate 1250W, 700kv, 80a motor, Castle ICE75 ESC, Hubin FM-2a timer, Flyermate 4500mah, 5S, 20C battery.    Flight time = 6 minutes & 33 seconds, lap times = 5.0 seconds, 3183mah used or 71% of 4500mah capacity, voltage - min = 13.3, average = 18.7 & max = 21.0, rpm range from 9480 to 9530, amps = 23.8 average & 39.2 max, watts = 433 average & 703 max.  This is probably the last time I will fly this setup for at least the near future.  I now plan to test other motors for awhile.  The flight today was very good.  Good line tension everywhere.  Onward and upwards toward smaller and lighter motors.

Roger,
With ~5.0-5.2 s laps, I fly no more than 300s---or 5 minutes, after release.

What are you doing for 6 min, 30 s???

That's a lot of round and round!

One way to cut down of power usage is to shorten the flight time to what you need.

So this is just to ask?

One thing you find with electric is everything happens at the same time to within about 5s (one lap) simply because when you push the button it goes. I carry a "Talking Timer" with me on every flight. I push it's start button when I push the timer/throttles start button. I typically setup the Talking timer for 6 minutes. Every minute it gives me a mark. It is sort of comforting to know when it tells me one minute left, I am usually vertically climbing into the 3rd loop of the clover. At the one minute mark, it begins a count every 10 s. I know the power will cut near the 30s mark. The bird is on the ground and I am walking to it when it hits "0". Things are really that regular, even with the wind. I leave about 3 or 4 laps after the clover pullout. I figure that gives me on time to postpone a maneuver for a lap. If I need more than that, it is just too windy anyway and so either I should go for the maneuver or I shouldn't be up and flying anyway! So I see no need to have a lot of laps at the end.

The Talking timer is useful if you want to go up and practice a particular maneuver--you always know when the timer/throttle is getting ready to cut power. No more power out during a vertical climb!

I had thought you were putting in full pattern flights and wondered why your time was so long. I agree for what you want to do, it is fine.

Running on the ground with the flight prop at flight RPM reauires somwhere between 1.5 to 2x the curent load you will see in flight. The 35-48 is more than up to the task - check the temperature after a FLIGHT and and I think you will be quite happy with it.

Yesterday all our snow melted, today the bottom fell out of the thermometer and we've had steady snow since around noon.  I am SOOOOO jealous of you guys who can fly this time of year!

Dorin,
Dennis is just turning into one of those "elitist good weather only" flyers .  The only thing to you need to fly is space (which we have) and a good set of lines.  Cool weather, wind, light and flying partners are just minor obstacles to overcome...
John

Hooray! - We got to fly again today!  I flew the Turnigy 35-48 800kv motor for the first time.  I tried to keep everything the same as with the larger Flyermate motor including prop APC 12x6 electric pusher, flight time = 6 minutes and 33 sec, lap times = 5.0 sec on the same Pathfinder electric test plane.  The smaller Turnigy motor flew the airplane just as well as the larger Flyermate motor but I was suprised to find that the smaller Turnigy motor acutally used a bit more power to do the same job (3322mah vs 3183mah for the Flyermate motor).  I also noted that the Turnigy motor was quite warn (almost hot) at the end of the flight where the larger Flyermate motor was barely warm at the end of the flight.  It appears that if I went to a slightly lower capacity battery to save weight the larger motor would use almost exactly 80% of a 4000mah battery but the smaller motor would exceed the 80% rule slightly (by 3%).  The only advantage I can see at this point to the smaller motor is that it weighs about 3.46 ounces less that the larger motor.  However, I did not notice any differance in the flight charactistics in the Pathfinder with the smaller motor.  It is a little early to make any real conclusions yet but the data was a bit suprising because I expected to see smaller power usage and enhanced flying performance.

I am waiting for a 4000mah 4S 20C battery that I have on order to test the higher 900 & 1100kv Turnigy 35-48 motors.  I will also test the Turnigy 42-50 650kv motor using the same prop, rpm & 5S battery on the Pathfinder when I get a chance.  That may take a little while because my wife is having hip surgery tomorrow and I think we will both be out of commission for at least a couple of weeks.

Hey, Dennis - I feel for ya buddy but at least you have the priviledge of enjoying copious quantities of that pretty white stuff.  We can only enjoy looking at the mountains east of us to see that white stuff.