affordable, lightweight 35% E-conversion

[Bodywerks]

During my two year stint in Colorado Springs, flying at 6800 feet ASL, I found myself wanting more power. Engines don't breathe too good up there, props don't grab air so well, and wing loadings feel higher and the plane has to fly faster to maintain lift.
This put me in a tough situation: I could just bolt on larger engines to my planes but that, in turn, would increase my overall weight. I started messing with small park flyer electrics and found the instant and reliable throttle response, coupled with power-to-weight ratios well in excess of 1:1, and no clean-up afterwards to be very attractive. I then moved up to converting a 60 size plane to electric and was again pleased...
Well, when it came to my 35% plane, I stuck with gas because I was under the assumption that converting it to electric would be way too expensive, due in a large part to the high cost of lipo batteries. That was until I discovered maxamps batteries (www.maxamps.com)...a typical battery setup for a 35% plane is about 12 cells and 8,000-10,000mah. Big name battery companies sell such a setup for about $1,000-1,200. I was able to get two sets of maxamps batteries for around that same price range!
Now, that's not to say that big name batteries aren't justified in charging what they charge. They guarantee high performance and have proven it. Maxamps doesn't advertise much and, by the looks of their site, they got their start in the R/C car industry.
Anyway, I have been running them in my 60 size and slightly smaller planes with great success, so they have proven themselves to me, and that's what matters!
As for the motor, Steven Neu is known for the very highest efficiency electric powerplants in the industry, and they just so happen to have an inrunner capable of 5500+ watts! The boys at www.e-flightline.com have already done their homework on this motor so I am using what they recommend, which is the 2215/2Y B.A.M (means "big a$$ motor"). It requires a 6.7:1 gearbox to swing a Tennessee Customs 30X20 prop! That's right - 30 inches - it's a friggin' windmill! E-flightline has also developed a nice motormount for this setup, so I went with that, too. Get this - the total weight of the motor/gearbox, mount, and prop adapter is only 45 ounces! Also, the total cost, with prop, was only around $900
The speed control is none other than Castle Creations' Phoenix 110HV. It is rated for 110 amps, but can handle much more than that, according to the knowlegeable folks over there. I suspect they're right, as the people I know that have successfully used this powerplant are pulling over 125 amps WOT, and I have heard as high as 140. The speed control runs around $230
So, for the whole deal, with one set of batteries, you're looking at somewhere in the area of $1700. Compare that to the cost of a 100cc engine, a pair of cannisters, prop, ignition battery, throttle servo, and some sort of ignition kill and you will find that the cost is pretty darn close.
Now, that's obviously not considering the cost of additional batteries, or the charging equipment, but I would assume that someone stepping up to this size of plane would already have at least one charger/balancer capable of charging a 6S pack, which is really all you need. Of course, more chargers or a more expensive charger will make charging the packs faster, so I currently have two Thunder power 1010C chargers with TP-210 balancers to do just that.
The airplane is my Aeroworks 35% QB 260. Mine was 25.5 pounds, dry, with the BME 110 and stock mufflers, but others using more popular engines are averaging 27-28 pounds. Now add 1.5 pounds in fuel and you are looking at anywhere from 27-29+ pounds for their take-off weight. Let's keep that in mind during the build...speaking of build, let's get to it!

[Bodywerks]

First thing to do was remove the engine, throttle servo, ignition, battery, tank, and plumbing - done!

[Bodywerks]

Now, to prep the engine box/fuse for a motor, battery, and electronics:

[Bodywerks]

I also wanted to cover up that epoxy filler from some damage I did to the wood when the engine was removed. it's a VERY light coat of speckle paint and cleaned it up nicely, looks-wise. You will notice a scoop on each side of the engine box. I have since removed them after the smell of my brain fart cleared!

[Bodywerks]

Here's the business end. The dang motor is no bigger than a coke can, but believe me, it packs one helluva punch! Perhaps I should compare it to a JOLT! cola can, LOL!
The motor mounts via a 10-32 threaded rod through each of the aluminum tubes into blind nuts in the firewall - simple!

[Bodywerks]

A couple more shots of the front end. Notice the use of nylon spacers. You can find them at ACE Hardware and I have used them to space out 100cc gas engines, so they should be plenty strong for this application. I also used a smaller one to keep the motor leads spaced apart.

[Bodywerks]

On to the inside of the fuse. I had to add a couple wood rails to the bottom to support the batteries, and also to raise them off the deck to allow for some air flow along their bottom. Also, because of the tristock behind the firewall getting in the way of the batteries, and to kinda redirect any airflow through that firewall, I added a piece of 1/8" light ply with "strategically located" lightening holes to space the batteries back a tad...

[Bodywerks]

Here is the 12S2P 8,000 maxamps batteries installed and strapped down. I have it set up so that only half the total current flows through each Dean's plug. The two that are already plugged in are in parallel and I still have an open circuit. As soon as I plug one of the other plugs in, I have a closed circuit. Pretty straight-forward...
One thing that is nice about this setup is that I can use a resisted jumper (approx. 15ohms) inline with the first battery when I plug it in. This prevents the BIG spark. Then, while the esc is doing its cell count, I plug the remaining battey in to keep the circuit closed while I remove the jumper from the circuit and reconnect that battery. It sounds like a chore, but it is actually quite simple and saves your connectors from damage over time.

[Bodywerks]

Air exit hole cut out. Pretty self-explanitory - just make sure it is larger than the inlet. 2:1 ratio seems to be about right.

[Bodywerks]

With the loss of vibration by going electric, servos don't work as hard and rx batteries don't need to be as big. So I went with a couple TP 1320 packs. They dropped almost a quarter pound off my final weight. I have already flown this plane and I eat 100 mah per pack on a 7 minute aerobatic flight

[Bodywerks]

more

[Bodywerks]

All done! I know it seemed quick, but with money, moving, and work, it has been a few month process. In reality, I could have done this in a couple weekends, easily. I am a hair under 27 pounds. This is the same weight as most lightly equipped DA-powered versions of this plane come in at, without fuel, so my take-off weight is over 1.5 pounds less!

[Bodywerks]

and finally some flight pics:

[Bodywerks]

Immediately after a 6 minute flight, with about a 20 second torque roll, some vertical point rolls, stall turns, a rolling loop, some high alpha, and some horizon-horizon slow and point rolls, this is the pack temp - me likes!

[staggerwing]

Interesting thread. Just curious about actual size of plane, prop clear,RPMS @ WOT, & what are your performance evaluations ?

Bob

[Bodywerks]

Also, initial amp readings show 122 peak, or about 5,000 watts. This is on an unprogrammed speed control and new batteries. I should be able to get about 5300 watts with a little work, for almost 200 watts/pound. That is not ballistic by any means, but I already have plenty to hover and pull out with authority for a few seconds, and that at only 180 watts/pound. I would MUCH rather have this kind of power at my sub 27 pound weight, than to have 7500 watts of power, but at the expense of an additional 3+ pounds in weight...LIGHTER IS BETTER!!!

[Bodywerks]

Anyway, that's about it. If you have any questions, comments, suggestions, or criticism, bring'em my way - I can take it, LOL!

[Bodywerks]

Interesting thread. Just curious about actual size of plane, prop clear,RPMS @ WOT, & what are your performance evaluations ?

Bob
This is the Aeroworks 35% QB 260, has a 104" wing and about 1870 squares.
I am spinning that windmill at 4,000 RPM. That doesn't sound like a lot, but you have to remember that it is 30 inches in diameter and has 20 inches of pitch compared to 28 inches and 10 inches of pitch of a typical gasser prop. I can tell you that it hurts my legs to hold it back just as much as the gas setup did! In fact, I used a calibrated force gauge to measure the thrust and am getting around 36-38 pounds.
Performance evaluations - well, it's a little slower-flying, overall, but the peppiness it has in a hover is quite unreal! It will also pull right out of that hover, it just doesn't go vertical very fast. The bigger prop doesn't seem to affect flight performance much at all. If I notice it anywhere, it is in a snap - the plane seems a bit reluctant to enter that gyration effect.
Overall, I like it and it is just plain fun, but definitely better suited for low, slow high-alpha stuff, hovers and junk like that. With the current prop, I don't think it would do well in upper class IMAC-type stuff, simply because it is a bit to slow at mild power settings, which means you'd burn the amps that much more just keeping the horizontal speed up and might run out of battery before the second was over (they typically make you fly two sequences per flight). However, they do make a 28X24 prop that a couple guys have been trying out. It will obviously increase the flight speed, and I think it draws a bit more amps for more power. Overall, I like flying it and LOVE that gearbox whistle and the instant throttle response, but I wouldn't consider it a replacement powerplant for my next 35%er - I still plan on putting a DA 100 in it.

[Bodywerks]

Oh, and with the fuse level, the prop clears the ground by a good 4 inches. This plane lands almost tailwheel first, so there is even more clearance on landing.

[staggerwing]

Appreciate the input. I have a used 33% 330L I'm toying putting EP in just to do it, not for any exotic performance, so your thread is of special interest.
Also I'm of the "large prop lotsa thrust school" w/ a low KV motor & your application communicates that type of performance well.

[Bodywerks]

Exactly. It seems that a few manufacturers are entering into the "what motor do we need to turn the prop that that gas/glow engine turns at the same RPM" school. It's an option, but a small prop at high RPM's is typically less efficient than a larger prop at a lower RPM. Gearing this motor at 4.3:1 to spin a 27 or 28X10 at 6500 would not be an efficient setup.

[BoneDoc]

Nick, If I can get mine to 20 lbs, will that tempt you to build a kit yourself :D?

[Bodywerks]

Dude, you'd be my new hero!

[BoneDoc]

Count on it! I've seen your work before, and I know that you're quite a craftsman. When you build a kit from the get go, there are so many ways you can do to drop the weight of the frame that you don't have the option of doing with ARFs.

[Bodywerks]

True that.

[BoneDoc]

Nick,

What do you think about using dual UBEC instead of receiver batteries? It'll have the redundancy with some weight savings there also. You can drop half a pound there.

[Bodywerks]

Never tried it. I imagine it would work, but would rather use a couple TP 730 mah 2 cell packs and duralite 6V, 7.5amp regulators. The batteries would weigh 3 ounces total and the regs would weight 1.5 ounces. They have one with a standard switch coming off a third wire from the reg. I am pretty sure the switch opens a circuit to turn the regulator on. Assuming this is the case, you can remove the switch part and just put like a female JR lead on it. Then, to turn it off, you would plug a jumper into that connector (basically just like what a binding plug looks like). To turn it on, remove the jumper. Fromeco regs use this same type of circuitry.
So, with something like that, you'd have a seperate power system for your radio, and it would only be like 1-2 ounces heavier. The 730's would be enough for 3 flights, easy. And, if not, just plug a couple more freshly charged packs in when you change the main battery - you have to remove the hatch anyway...

[Mike Parsons]

I used the Koolflightsystes dual ubec system in my 87" Yak for the better part of two years. Never let me down.

Congrats on the project Nick. Very well done.

[BoneDoc]

Thanks mike,

Did the UBEC came off the main Deans or one each of the 2 packs to make the series?

[Mike Parsons]

Each UBEC is dedicated to a pack (if using a 2 pack setup). I installed a micro deans connector on each side of the Serial adapter and the mating connector on the UBEC. The UBECs were then hooked into the RX using a Y cable.

Worked really well, light and it was nice knowing I had the redundancy.

[KatManDEW]

Very nice Bodywerks. What timing are you running with your 2215? Do you have any video?

Bonedoc: I saw part of your thrread about your 35% Dalton Aviation Extra 260. I need to find out more detailsabout how you accomplished the lower weight. Like where and how you reduced the structure. I have a 35% Katana Kit that I would like to shave down to ~20 pounds.

[Bodywerks]

Right now I am running standard timing. I understand I can squeeze a few more hundred watts by advancing it, but I am still breaking in the batteries.
Sorry, no video - yet. I have no clue how to upload videos to computers and all my friends stink at videoing, except my new friend Teryn. It's just a matter of getting together to do it.

[KatManDEW]

I'm running 4 degrees timing. I haven't gotten around to measuring amps yet. I'll do the next time I have it out.

I think you can upload video here. I put them on my own website, or my club's website.

[ludovit]

Bodywerks,
Nice job on the conversion.
I am buying pretty soon Great Planes Cap-580 33%.
It will be converted to same setup you have except I will go for Maxamps 12S-10000.
I think that Neu 2215/2Y is hard to beat for weight and performance.
I am looking in to this setup for a while.
I used to fly all my planes including my large scale electric powered.
I have very good luck with Maxamps for last few years I am using them.

I went to gas last year (just to try) and I don't care for it. I love the flexibility and simplicity and hole another reasons of the electrics. That's why I am going back to electric powered planes and never go back.
The GP Cap-580 33% weighs around 27 lbs with DA-100 according rcuniverse posts.
I did calculate the electric setup and should be almost identical to DA-100 setup weight dry with no gas, so overall electric setup should be lighter (no fuel)

How long your 8000mAps lipos last in the flight?
I am hoping for 10 min on 10000mAmp @ sea level.

Also how is your Castle Creation SC holding. It is cutting out? You might be at the limit.
Please let me know if it holds well and doesn't get very hot, so I know which speed
controller to order. Jeti SPIN-200 or Schulze 40-160.

Thanks
Ludovit

[Bodywerks]

Which 10,000mah packs from maxamps? Are you talking about going with 12S2P 5,000's or the single 10,000 mah cells? I ask because I had the 10,000 single cells and they lasted about 6 seconds at 120 amps and then smoked. Also, even the 5,000's will add another pound to the airframe, which is something you REALLY want to keep in mind if you think you will be any heavier than about 26 pounds. Bang for the buck (and the weight), you're right, the 2215 is a powerful motor. But if I had it to do again on this size of plane, I think I would rather have it at about 28 pounds with a 6,000 to 7,000 watt power system. I am not sure what that would be, but Neumotors is working on a 2230 motor that might answer the call. If you think you can get the Cap down to about 25 pounds with the 2215, that wouldn't be too bad.
I set my timer to 7 minutes and the timer runs out right about when I land. I put about 2300-2700mah back into each 4,000mah pack. I think I gould get 8 minutes or so, safely. The batteries come down at about 105-115 degrees.
The Castle has yet to cut out on me, but I am most definitely pushing the limits of it, and it comes down at about 140 degrees. I might have considered one of the chargers you mentioned to do it all over again, or the new Hacker 200 amp esc's.

[ludovit]

Bodywerks,
Thanks for the heads up on the Maxamps 10000 cell Lipos single cells. That was the Lipos I was going to get. I might also rethink the Cap's weight. With those 12S-10000 it would be around 27 lbs.
I might wait for the Neu 2230 motor.
Far as speed controler I am going with Jeti SPIN 200-amp (Little pricey, but it works awesome)

Check this video http://www.katmandew.com/Video/PP_Extra_1.wmv
Guy is flying with this setup : Neu 2215/2Y, TP 12S-8000, 30x20 prop ,25LBS,
Jeti SPIN-200amp SC.
Here is link to the guys thread http://www.rcgroups.com/forums/showthread.php?t=480327
He burned Castle Creation HV-110 . Then he switched to Jeti SPIN-200 and SC doesn't even
get warm.

Thanks again for the valuable info.

Ludovit

[ludovit]

Bodywerks,
I forget to ask. Did Maxamps replaced your burned 10000mAh Lipos? They should hold
120 Amps all day long.

Ludovit

[ludovit]

Bodywerks,
Did you noticed on Neumotors website under the news, that the new 2230/1.5 was
tested on 18 cell lipos ( ouch, that might be too pricey for me).
I hope 2230 will pump out some decent power on more moderate 14S lipos.
Otherwise I will have to stick with 2215/2Y and keep the Cap's weight down.

Ludovit

[rcelectfly]

Bodywerks,
Did you noticed on Neumotors website under the news, that the new 2230/1.5 was
tested on 18 cell lipos ( ouch, that might be too pricey for me).
I hope 2230 will pump out some decent power on more moderate 14S lipos.
Otherwise I will have to stick with 2215/2Y and keep the Cap's weight down.

Ludovit

You can use a 2230 on 14s you just need to order a different wind with a higher kv.

Chuck

[KatManDEW]

Check this video http://www.katmandew.com/Video/PP_Extra_1.wmv
Guy is flying with this setup : Neu 2215/2Y, TP 12S-8000, 30x20 prop ,25LBS,
Jeti SPIN-200amp SC.
Here is link to the guys thread http://www.rcgroups.com/forums/showthread.php?t=480327
He burned Castle Creation HV-110 .

I burned two of them, before the plane got off the ground. I'm much more comfortable with the Jeti 200.

[Bodywerks]

Bodywerks,
Thanks for the heads up on the Maxamps 10000 cell Lipos single cells. That was the Lipos I was going to get. I might also rethink the Cap's weight. With those 12S-10000 it would be around 27 lbs.
I might wait for the Neu 2230 motor.
Far as speed controler I am going with Jeti SPIN 200-amp (Little pricey, but it works awesome)

Check this video http://www.katmandew.com/Video/PP_Extra_1.wmv
Guy is flying with this setup : Neu 2215/2Y, TP 12S-8000, 30x20 prop ,25LBS,
Jeti SPIN-200amp SC.
Here is link to the guys thread http://www.rcgroups.com/forums/showthread.php?t=480327
He burned Castle Creation HV-110 . Then he switched to Jeti SPIN-200 and SC doesn't even
get warm.

Thanks again for the valuable info.

Ludovit
The thing with these Neumotors is that they are SUPER efficient! As they spin up, they start to want to act like a generator. I am no electrical genius, but I have had several discussions with guys that know WAY more about electron flow than I do, and have run the very same equipment that I have, extensively. One thing they mentioned was ripple current. What it is is beyond me, but they said that wires that are too long have higher impedance and are more susceptible to such current. I was told, emphatically, that the wire length from the motor, all the way to the battery, needs to be as short as practically possible to reduce the possibility of these ripple currents. Following their advice, I shortened the wires on my ESC by about 6 inches, and the battery leads are only about 3.5 inches long. I also am running the 120 amps through two Deans plugs to keep the resistance down. This may be why I haven't blown mine up.
As for the 10,000 batteries. I had them install two sets of 12awg leads out of each 6-cell pack to split up the current flow (flowing 120+ amps out of one 12awg lead would be a bad thing - 12awg is only rated for about 80 amps max). Doing so may have adversely affected their performance. Combine that with the high efficiency of the Neumotor and those ripple currents, and they may not have been up to the task. The guys at Maxamps admitted, after the fact, that they are an economy cell and don't even have copper tabs. I purchased their warranty, and they gave me a full credit toward the purchase of their 4,000mah packs. So far, those have been great!

[Bodywerks]

Bodywerks,
Did you noticed on Neumotors website under the news, that the new 2230/1.5 was
tested on 18 cell lipos ( ouch, that might be too pricey for me).
I hope 2230 will pump out some decent power on more moderate 14S lipos.
Otherwise I will have to stick with 2215/2Y and keep the Cap's weight down.

Ludovit
Yeah, I haven't kept up with that motor lately. I think it is actually for the 40% planes, and capable of 18Kw!!! If it is light enough, though, you could easily drop down to 12-14S and gear it differently for 6-8Kw.

[ludovit]

I got my GP Cap 580 33% few weeks ago. My second girl Sienna was born 10 days ago, so the process of building it will be slower. I have elevators hinged and servos
installed. Now I am working on main wings. There is realy not that much to put
together.
I am going with Hacker A150 :D .I hope to order the motor with SC combo soon.Setup is heavier then Neu 2215 setup, but I like the outrunners. Also it will be easier to balance the plane.
I didn't order rudder servors yet. It will depend where the CG will end up. There is 3 options for rudder servos install. Either giant scale inside the fuse or outside the fuse with either 2 o 4 standard size servos depend on torque.
Motor will swing either 26x12 or 27x12 on 12S2P-8000.
Motor can go up to 14S.
SC is Master JETI SPIN-200.
I played with numbers in the Motocalc, the motor should be powerhouse
for total weight of the Cap around 28.75 lbs.

(Cap looks strange with no ailerons on the pictures)

[ludovit]

I am moving my post to new build log thread to here:
http://www.rcgroups.com/forums/showthread.php?t=737102#post8107554

since this thread is about 35%. My Cap is 33%.
Any responds please go to above thread,

thanks

[appleflyer]

I am doing a 31% sukhoi su-31 conversion with a HXT 80-100-130kv motor and i was planing on about 4000-4200 watts on 12s.

Does anyone have an idea what amp hour battery I should use?

[Bodywerks]

I am sure you have already figured it out, but you want about 8,000 mah.