Forced_Induction

Hello all,

I have looked quite a bit online to see if anyone else has been trying what ive done, but I havent found anything yet. Over the last couple years I have shifted my planes and helis to electric, and have been loving it ever since. A few years ago i got a hold of a shrike 10 kit. so i decided to build it electric. I started using a hobbyking 3548-1100 motor. 1100 KV on 5s gave me a high rpm with a small prop. after puffing a couple packs, breaking the nose off, damaging a leading edge, and having a ton of fun going ridiculously fast with it, i scavenged the esc for another project and it sat on a shelf for a couple years. the other day i was going through some crap in the basement and i found a carcass of a 500 heli that i smashed up. I used a hobbyking typhoon 500 motor in it and a light bulb went on.

the typhoon 500 is 1800 KV and can handle way more power than the 3548 i was using. the 3548 was capable of around 700w. i was pushing it to 1100w and being in the open air, i never had any issues with burning the motor up. so i swapped out the 3548 and put in the 500 heli motor. testing with a few props showed that a 7x6 pulls right around 85a static. Im using a YEP-80 ESC with it which is good for 100a 10s bursts.

I maidened it today and everything went well except i couldnt run full power. every time it wound out, it would start pulsing. I suspect that it was the timing setting but i didnt have the programmer to try changing it at the field. I played with it a bit when i got home and it seems like its liking higher timing than the 12 deg i was running before.

I like this setup alot. my old setup with a 8x10 prop was a bit of a head turner at 210kph (doppler), and this setup should go even faster. Im planning a new plane MAYBE this winter that will use a bigger motor. id like to use a 40 sized delta airframe (diamond dust, screamin demon, or another, im open to delta suggestions) and run a scorpion heli motor on 12s. the pitch speed looks pretty freakin insane =).

please feel free to leave any suggestions or stories of electrics, or anything else really. I havent seen setups like this discussed very much so id like to start it up.

MJD

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http://www.rcuniverse.com/forum/extr...l#post10562465

http://www.rcuniverse.com/forum/extr...l#post11629874

http://www.rcuniverse.com/forum/extr...l#post11568246

I'm not sure what you mean specifically by nobody else trying what you've done. The electric RC world is full of people overpowering airplanes for speed, whether electric models or converted glow models - YouTube is full of examples. The above threads are on this forum. While this forum is not specific to glow engines or IC engines, generally it is mostly glow with a smattering of electric projects.

Forced_Induction

just to clarify, i am not claiming that im pioneering anything. I just havent read much about people electrifying deltas and other airframes with high KV high voltage systems. Funny thing, i read a post on the speed freaks wanted thread minutes after i made the post where a guy used a 4025 scorpion heli motor in a warbird and got a pretty nice speed out of it. and WOW that jackel has a MONSTER power system. I guess i just need to search more.

Im looking at a build this winter. A diamond dust with a HKIII 4025-650kv scorpion running on 12s. the small size of the fuse looks like its going to be the limiting factor. I might have to series 4x 3s 2700-3300 packs and lay them flat in the fuse. Im not sure how this will work oout as I havent seen one up close nor have i bought the kit yet.

Im curious what kind of airframes/power systems those speed cup planes are. i noticed one prop had 12/24 written on it in the pic, thats some serious pitch. Looks like more searching =)

combatpigg

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Build the center section to suit your needs with a bit of air cooling space in mind. You can form 1/16" balsa sheeting to create a compound curved surface that blends the center section to the profile of the wing. I use file folder paper to create rough patterns, then transfer the pattern to the balsa sheet.
If you do not like that approach, building a simple [but sleek] warehouse behind the engin...oops, I mean motor.... isn't such a big deal.

Forced_Induction

I was thinking of putting 2 3s packs in front of the spar and 2 behind. might be able to make a nice hatch to cover all of the rear packs and most of the front ones. it looks like some 2700 3s zippy compacts will fit side by side in the center section.

that was my thought until i started looking at the pylon racers and hotliner setups. holy s#!t those things are fast! might be changing my plan lol

MJD

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Yes indeed.. when you look at the standard fare being flown in the electric pylon world you soon realize there is some really fast off-the-shelf s--t out there! Lots of fun to be had. For a Canadian supply option, look at Icare RC.. some nice stuff there.

I wasn't jumping on anything you said earlier - just pointing out that upping the power on electrics and electric conversions with higher Kv/wattage motors is a popular fix that many people are into. This forum only has a few electric speed projects listed, likely because so much fast electric stuff is off the shelf and not considered extreme. These days it is almost harder to go really fast with glow as you can tell by the German speedcup results. But it is still more cool..

But powering the crap out of a cheap built up delta has its own appeal too. You can emulate a strong .50 with 1200-1400W lekkie power - figuring 1.5hp to the prop and 85% efficiency. On a Demon I'd be surprised if that didn't take you well north of 150mph but I won't make any claims until I do it myself. For reference the same model on a Jett .50 can do 170 or better - this has been radar verified.

My present Demon build (which started last year..) uses only standard LHS stuff - E-flite BL32 motor, 75A controller, 5s pack, 6x5.5 prop. We'll see how that does once I get it together.

Currently the speed guys are heading in the direction of high torque outrunners and extremely high pitch props, like the 12x24 you saw. Listen to the eery noises at launch with those high pitch blades thrashing the air around.. takes a bit of airspeed before they hook up. But the speeds are astonishing. Others still go the high Kv, high rpm route, and they go fast too. Those airframes are generally CF composite and made in CNC molds. The standard 10cc glow speed model over there costs about 600 Euros for the airframe as an example, those electric speeders are larger and worth a fair bit more I imagine. The 10cc speed guys are running modified OPS/Picco/OS engines in the 25-26k range on 8x12, 8x13 props. I think all the lights flicker for several miles around when they punch the throttle on the electric speeders, they are pouring a pile of power into those motors.

Forced_Induction

thats what ive been looking into the last little while has been high rpm/low pitch vs low rpm/high pitch. seems like the high pitch setups are hard to launch and pull MASSIVE current for short bursts. the sound is definately interesting though. it seems like i can get a better setup going with a neu motor on a delta and using lower cell count. same speed with less power. looks like i really have my research time to put in. it makes it a bit difficult when theres not much info readily available on setups like those at the speed cup. at least not much in english. do you have a link to any of the motors they use? the only one i could find was a limited edition scorpion motor.

MJD

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Not really, the little I have seen is on .de forums as well. F3D who posts here on occasion is a well-known glow flier at the Speedcups, he would likely know who some of these guys are. Check out his MB Profi .40 powered models - go to YT and search "doppelprinz". One Profi at 33k ain't enough, let's use two.. egads.

I sure post more frequently when I am bored at work..

f3d

Here some pictures of the airplanes the motors and the controler.

Most motors are rewired with a thicker wire up to 1,8 ( 2mm ) and able to take up to 300 Amps continuisly.
The controler can also provid up to 320 Amps continuisly and more than 500 for 5 sec.


The americans are years behind and miles away from fast speeding.

Regards Michael

Forced_Induction

now thats ridiculous. those windings are HUGE and bursts to 500A?! no wonder theyre running parallel wires to the motors from the ESC. Well, i guess i know now that i wont ever get to that level. thats more than i can afford to pour into the hobby. Its good to know that there are people pushing the absolute limits of these power systems. And the hard hats are hilarious!

Any idea what kind of flight packs theyre using?

iron eagel

It may be the timing or the response time of the ESC when used with a very high rpm motor, I have had similar issues using bargain ESC with 6 pole motors at high rpms that went away with a high quality ESC.

iron eagel

Not really sure about the packs they are using but they limit the power levels for each flight to 2.6 KWH. If I recall correctly they use up to 10s but do not allow parallel packs so the packs have to be able to handle the 300 to 500 amp power levels.
by the way another electric speed project I am playing with:
http://www.rcuniverse.com/forum/extr...lta-build.html

MJD

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Ferrous eagle - looks like I might get my electric Demon flying sometime this century, I seem to have picked it up out of mothballs and I have finally found a motor mount I think will work well with the mounting plates in the Maxx 28mm clamp style mounts. I have 4 sets on order to bolt to try out in this and that, e.g. I seriously need to electrify the 26" Demon. Easier with outrunners I guess, but I like the skinny little 28mm motor can and you can get a fair amount of hp in that diameter.

Forced_Induction

500A on 10s is 18.5Kw, 300A is 11.1Kw. I might be a bit confused where your 2.6Kw number comes from.

I put 4 flights on the shrike today. crazy fast (definately a perspective opinion =)) off a fresh pack. the pulsing issue was a combination of low timing and the low voltage cutoff. I tried re-enabling the LVC on the second flight after the first went great and it started pulsing again although not as severe. I maybe should have taken a hint though as i overheated and puffed the pack so bad that one of the cells melted the heat shrink off along the sides and 3 cells puffed. made it a ***** to get the pack out from the bulkhead it was wedged in. Im planning a new approach using 2 6s1p 1300 packs in parallel. they should fit nicer, give me more amp handling and allow me to lower the amperage to get the same power out of it. i was running a 7x6 before but ill probably have to step down to something like 5x5.5 (according to ecalc). should make for some more high revving fun times and hopefully more reliable as the 5s setup has been nothing but trouble. If im not smoking escs or puffing packs, im breaking motor shafts and props on landing. Makes me glad im using hobbyking equipment going through components like this lol. made me say "holy ****" the first pass i did though!

MJD

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There seems to be an extreme speed "everything" these days..

http://www.youtube.com/watch?v=fYOsNp4O7AU

Okay, sorry OP, I admit that was a little out of left field.. back to fast electrics..

Gimme a break, it's Saturday night.. and I went flying today, though not too fast.

Forced_Induction

lol now thats impressive. I used to play the tuba in school so i can respect the skills it takes to play it like that. nothing wrong with a bit of off topic every now and then.

I too put 12 flights in today between my shrike, fusion 50 heli, and elecric u can do 60. It was a good day!

MJD

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I got an hour and a half instruction in a Tiger Moth today, so it was a good day for me too. The best part was dropping down through a hole in the clouds at about 4000' over Wasaga Beach.

I've played trumpet for 40 years.. that's why I know what a monster this guy is. Hilarious and totally, insanely musical at the same time. Totally entertaining.

This electric Demon I'm working on likely won't be insanely fast, but should be quick enough for fun. Depending on cell count and prop can run between 1100-1400w input. I'll try it first on 5S and a 6x5.5 prop, that's about 1100w input and pitch speed of 150-something. My motor mounts should show any day so I can finish up the motor mount area and detail the front end. The rest is almost ready to cover.

I got some of these cool wing servo mounts/exit fairings recently, I've seen them in some composite ARF's.. I will try to use a pair on this.

Forced_Induction

what motor are you planning on using?

I ran the numbers this afternoon after i smoked that lipo for a 6s setup. the same reason people are cutting out the center section of the spar is the problem i had on the shrike. no where for a pack so i hollowed out the center bulkhead just enough for the 5s 1800 pack i was using. If i run the 6s 1300s meant for the 6s 450 helis then i can put 1 on each side and i should be able to get a decent balance. ill have to prop down quite a bit but i should be getting much higher rpm. ecalc is showing 1400w, 67a, 33580 rpm and 180 mph pitch speed. im crossing my fingers for that!

Anyone have a rough percentage difference between theoretical pitch speed and actual speed? I know theres a lot of variables, but a close figure would be nice.

MJD

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It depends totally on the aircraft so there really is no correlation or rule of thumb. A cox .049 spinning a 4x4 prop at 20k has about 80mph pitch speed. So does a .46 spinning a 10-6 at 13.3 k. The question is, what can each pull at that speed with the power available? If the hp the aircraft requires to fly at pitch speed is being delivered, you can theoretically get there, and in actual practice since the way pitch is measured the aerodynamic pitch is often a bit higher.. so aircraft have been known to exceed the theoretical speed based on the listed pitch of the prop. And they have been known to fly a lot slower too. In terms of efficiency, the farther you are below pitch speed, the higher the angle of attack of the prop blades (for a given rpm), and so go too far and more and more of the available power is wasted due to drag. The art of finding optimum props is buried in these somewhere. Voodoo.

I would say if there is a rough rule.. if you have plenty of power available, you can expect to get there or thereabouts.

MJD

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Eflite BL32 2150 kV - the Habu DF motor. 5S on a 6x5.5, or 6s on a smaller prop. I think I need the 6" diameter prop for this large a wing, but we'll see. Not a crazy amount of power, but plenty.

iron eagel

I am using a 28 mm inrunner on my full size Demon similar to the one I used on the stingray. Running it with a 5.25X6.25 on a four cell I hope that I should be able to get it to at least the 200 mph mark, and as you know that is a pretty clean airframe with wings that are only 3/8" at the thickest..

iron eagel

I have found that with the stingray with it's 43" span it can't get up to sped with a 5.5 prop (at least on a three cell). The only good speed I have seen with the HET 2W-23 was with a 6X5.5 with the three cell on the maiden flight. I have tried it with everything from a 5X5.5 to a 5.25X6.25 on a three cell and even spinning at 27- 28K rpm best speed was about 130 mph.

MJD

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It will be an interesting experiment.

iron eagel

With the 43 inch span of the Stingray thus far all of the props under six inches are unable to get up to speed, with the Demon and it's 36 inch span I am fairly sure a 5 to 5.5 inch diameter prop may work. You know that my Demon is pretty clean, the only real compromise is the winglets instead of a single central fin.

MJD

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Mine is like my avatar with tip fins nicely blended in with epoxolite. Just a regular 6% thick Demon wing. But the 5S packs fits completely inside, and I will blend the nose in to the airframe some crude but reasonably effective way (just being honest..) in an attempt to keep it fairly clean. Should be sporty. I was looking at some Hyperion outrunners as alternatives.. the HS3026-1400 or 1600 look promising. I wasn't really familiar with them before. These would lend themselves well to a firewall mount and a simple cowl (vacuform?).