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  1. #1

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    Replacement for displacement.

    Hey guys, well, wouldn't you know it, the Dash 5 that I built for a friend is being traded back, and while I set it up for a .61, I honestly feel this would be the perfect classic electric.

    What are you guys using that's equal or better than a 61 hanno? (I know it may not have run on this engine, but as targets go, it's a goodun )

    BTW, I'm thinking 6s for the pack. size will be determined by fuselage dimensions, as always.
    Go knife edge your cub!

  2. #2
    doxilia's Avatar
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    RE: Replacement for displacement.

    Greg,

    Is the D5 being sent back the nice yellow and black one you've showed us pictures of? That should be a nice ride.

    We've been looking into 60-80 size e-drives lately as a result of a joint MK Super Chipmunk 120 project we're doing which we have drawn plans for suitable for e-power. The typical SPA "60 equivalent" drive is a 1400W unit often run on 5s if possible. Many of those models are built light to 6.5-7.5 lbs.

    Some of the larger and later Japanese designs are heavier though and more suitable for the big long stroke OS or YS's, whether 60's or 120's. If the Dash is an 8.5 lb+ 800 square plus model, it certainly makes sense to go with more Watts and 6s. For the Chipmunk we decided to turn 15-16" props which is what the 120's would turn as well. Several of the 120 size 50 mm can motors can weigh in the 400g range but we found a way to reduce the size slightly to a ~48 mm can and 350g while still capable of sustaining 2000W continuous.

    We went with Scorpion motors and there are both 450 and 515 kV variations. The latter can develop ~1600W on 13" props and 6s while the former needs 15-16" props to get into that power band. Even a 16x12 should be doable for closer to 1800W but the current draw starts getting pretty high on 6s in the 90A range. The 515 might be a better option if you want Hanno like performance on a 14" prop. I don't think a 13x10 will do it but a 13x12 might. You just have to watch the amps on the 515 as it is not designed for more than 6s which is what we want.

    You might want to download Scorpion calc to try out a few different configurations. Whether you use Scorpion motors or some other brand, it is a useful proxy tool. Many manufacturers use the same tool for their motors.

    David

  3. #3
    doxilia's Avatar
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    RE: Replacement for displacement.

    Greg,

    I just received the second Scorpion that I purchased - the 515 kV version. I will be using it on a Matt Saphir I on which I'd like to turn a slightly smaller prop than on the Chipmunk.

    I've attached a couple of snaps to give you an idea of the quality. They don't carry the cache brand name that Hacker, Pletty, Neu and the like do but they are very nicely made. I'd venture better quality than Rimfire, E-Flite and such. Doug Woodward (Fatherof4) is using one just like it in his Conquest IVe (build thread on RCG). He's very happy with it.

    I got a great deal on them from a store here in Canada that had them at 40% off so I couldn't pass them up.

    David

    P.S. The Scorpion performance table for this motor is here:

    http://www.scorpionsystem.com/files/...data_chart.htm
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  4. #4

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    RE: Replacement for displacement.

    Hi Greg,

    I bought a Scorpion HK-4035-400KV 8mm shaft for use in my Curare and on 10S it'll swing an 11x9APC at about 13K static and in the air performs about the same as my old ASP.75 swinging an 11x10APC. For personal reasons I didn't want to go over 12" prop diameter as I don't intend to fly turnaround or 3D with it and with a 10S 4Ah pack the final weight came out about .5kg heavier than a full 16oz tank of fuel, so somwhere in the 8.75lb range.

    This was a glow to electic conversion so it's heavy, if I were building one from scratch for electric, there's lots of places to save a bit of weight to to get it back to the 7.5lb range.

    I too was looking to replace the Hanno in the Slingshot and hoped this motor would do the business on 8S with a 12"-13" diameter prop but to be honest I'm very disappointed with it from a quality perspective. The sharp edges around the case where the wires come out are chaffing points, it would't be so bad if the wires came out the middle of the hole but when they installed the stator, it's on a bit crooked so the wires are hard up against one side.

    I only ran it for about 4 minutes in the Curare because the vibration was shaking the plane to pieces. Right from the first bech test there were bad resonances at certain RPM (bolted to a piece of 16mm thick laminated MDF and secured in a bench vise), which surprise surprise didn't get any better in the plane. A friend bought a similiar but different version of the motor and there were similar vibration issues. When it was running you could see the motor can bending and flexing. I sent mine back for "warranty", received it back and haven't even bothered to run it. It really needs a longer shaft so it can be supported by external bearings at each end. I ran mine front mount with no rear support, his was a back mount one with a bolt on prop adapter and it wasn't any better. I'll get around to machining up a longer shaft so I ca run a rear bearing in the old firewall to support the rear of the motor.

    Apart from spinning the prop at the right RPM, and honouring their warranty I can't say anthing good about Scorpion motors, even the hole in the prop adapter is/was too big for the 8mm shaft making it unusable. They're probably really good in a chopper where the only load is a pinion and they can run at some non-resonance RPM. My Scorpion (and my friends) certainly didn't like a gyroscope hanging off one end and certain rpm....

    But like anything YMMV...

  5. #5
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    RE: Replacement for displacement.

    Electification of the classics will mAKE YOUR HAIR STAND ON END....Sacrilege!!! LOL
    Regards,
    MattK
    (Rcmaster199@aol.com)

  6. #6

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    RE: Replacement for displacement.

    As does gasifying vanquishes MTK [:'(]

    Hehe, to be honest, I don't really trust the way in which I had to mount the 61, it's not pattern kosher IMO. Hard mount and no pipe, yechh!

    A friend swears by scorpion motors, but thinks that electrics are some sort of black art, so his opinion doesn't carry much weight.

    I figured I'd be looking around 400-500kv range, and if I can get 1.3-1.4kw, I'll be a happy man.


    Anyone tried the e-flite power 60? 400kv, looks to be good for 1.7kw (on 7s)..
    Go knife edge your cub!

  7. #7
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    RE: Replacement for displacement.

    BJR,

    I'm sorry to hear that the Scorpion HK didn't turn out well on your Curare.

    Not having any hands on experience with the Scorpions yet, I can't offer a second opinion other than what I already mentioned above however, it strikes me that loading up a lower kV helicopter series motor with an airplane APC prop might not be the best approach. I also feel that running our 60 size classics on 8 and 10s configurations is overkill causing the models to be overpowered and overweight at the same time. 8s might be a sensible option on the 6' 9.5+ lb 120 size birds mentioned in my previous posts but it does add a charging complexity requiring special chargers capable of 8s packs or two chargers if going 2x4s in series.

    I think the sweet spot in the ~65" span model is really with the 6s packs which allows one to add "fuel" at a weight of about 25-30 oz. It's possible that over driving a helicopter motor on a classic pattern prop at high voltages might be the culprit for the vibration. 400 kV sounds low to me if one is targeting 13+K. We're talking about a nominal 37x400 = 14.8K rpm requiring the very large 10s cell count. It strikes me that if one wants to turn smaller 11" props (by e-power standards) at those rpm's, it is better to increase the kV and lower the cell count. For example, on 6s, one could achieve 14.8K nominal by using a ~650 kV motor.

    If we look at the performance of the 400kV motor on 6s, one only gets 388W/17.5A/8.4K on a 10x10 e-APC. By increasing to the 630kV otherwise identical motor and prop, performance is 1300W/58A/12.6K which is actually a viable power platform for a Curare 60. Change the prop to an 11" and it will be right in the desired 2 bhp Rossi like power band. Comparing these motors to the aero S-4025-10 motor, performance on the same prop is 750W/33A/10.5K. It becomes clear that in a 6s configuration, one wants to be in the 600kV+ range of motors to turn smaller 10-11" props. Putting a small prop on a low kV motor at high voltages, achieves the desired rpm's but the power input is on the order of 2200W (!) which is suitable for a 10 lb+ bird still at over 200 W/lb. It might be that the motor is producing too much power, on too small a prop on too much voltage. Up the kV, lower the voltage and I think you'll be happy turning 11" props while keeping the model lighter. Someone here runs a 10x10 e-APC prop on a 600+ kV heli motor on 6s in a P8 and the plane moves out in spectacular fashion.

    With that said, the Hanno is a 2-stroke 120 4-stroke type motor and does well turning 13" props sub 10K. In that sense it is easier to match the performance of it with an electric motor turning props in comparable diameters on manageable 6s packs.

    As far as the quality of the Scorpions and accompanying hardware from an inspection standpoint, I can't say anything bad about them. The metal appears solid, the berings smooth, the collet and screws made of alloy rather than light flexible aluminum and the weld joints look well done. The accompanying X-mount looks like it might be made of the least strong material and although stout, it appears to be cast from metal that would yield in case of a crash with the intention of salvaging the motor while scrapping the X-mount. All this, of course, in reference to the Competition Series airplane motors shown above. I have bought at least 6 different brands of motors and these Scorpions rank high in quality compared to the others I have used. I just hope that they perform as well as I am optimistic about them.

    The one thing that is interesting to note with these motors is that there is no paperwork that comes with them. I found that somewhat odd but in today's internet era, it is understandable - all the information is online.

    David

  8. #8
    doxilia's Avatar
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    RE: Replacement for displacement.


    ORIGINAL: Rendegade

    As does gasifying vanquishes MTK [:'(]

    Hehe, to be honest, I don't really trust the way in which I had to mount the 61, it's not pattern kosher IMO. Hard mount and no pipe, yechh!

    A friend swears by scorpion motors, but thinks that electrics are some sort of black art, so his opinion doesn't carry much weight.
    It sounds like he wants to propagate the myth that basic physics is black art...

    I figured I'd be looking around 400-500kv range, and if I can get 1.3-1.4kw, I'll be a happy man.
    Greg, if you want to turn 11" props, keep it above 600. If you want to turn 13", 500 and if you want to go to 15" then 400 is fine but a 15" prop on a 60 size classic doesn't bode well. Make it a 120 size semi-scale pattern like the Chipmunk, Akromaster or Zlin, then, 15-16" is fine. There is no mystery to getting 1.4 kW - it's just a matter of how one gets there.

    Anyone tried the e-flite power 60? 400kv, looks to be good for 1.7kw (on 7s)..
    7s? [&:] Bleah! See what kind of a pain that is to deal with.

    I wouldn't touch that motor. It's fine on 60 size war birds - more or less. If you want to use big brand products, the Rimfire series is better suited to classics. E-Flite seems to have conceived all their motors either for helicopters, Extra's or pylon racing. There is nothing really there for classics IMO.

    David

  9. #9

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    RE: Replacement for displacement.

    Hmm. righto, back to the drawing board.

    How about a hyperion 40-25 630kv ?
    Go knife edge your cub!

  10. #10

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    RE: Replacement for displacement.

    Hi David,

    The trouble is that I'm giving away away so much efficiency running an 11" prop but you get nice smooth turbine like power. The old .75 I'm used to is rated to put out about 2.4hp. 1300W just isn't going to cut the mustard at 100mph, BUT at 60-70MPH with a 12-13" diameter prop 1300W is in the ballpark. The math says 8+lbs of thrust at 100mph = 2+horsepower.

    I morally object to people flying a classic with a 14" prop turning in the sub 10's , it'd be like pulling the V-twin 2-stroke out of my TZ and replacing it with a 650cc single 4-stroke.

    The Scorpion on 10S (it's rated for 12S), pulling about 65A static with the 11x9 gave very similiar performance to the .75 two stroke and honestly up to about 9000rpm was very smooth but when pushed beyond that the whole thing got very bendy. I was running glow props on it as well, not the floppy E props. When you compare how solid the front end of a glow motor is to an electric you can see it's asking a lot from it. But it's all experimentation. The 8mm shaft wasn't flexing from what we could see but the "spigot" (for want of a better word) that the bearinges and stator are mounted into. On the rear mount arrangment my friend was using, you could grab the prop and bend it from side to side watching the can flex around in relation to the stator.

    Don't let mine and my friends not-so-positive experience with the Scorpion outrunners put you off from experimenting. His was a S-4035-330 he intended to run "rear mounted" on 12S in a Falcon 120 but it was too bendy for that. He turned it around to a front mount, with a 10mm ply box around it with external rear bearing support and it's bench testing a lot better. Both motors up to about 9k were fine but started getting out of shape after that. I'm beginning to think a "typical" outrunner design doesn't scale well, just like we don't see too many .15+ sized engines based around the design of a Cox .049...

  11. #11

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    RE: Replacement for displacement.

    I'll chime in....

    Conquest IVe
    9.75 lbs rtf
    Scorpion 4025-10
    Sky Lipo 6s 5000 mAh 30c
    E-Flight 80 esc
    APC 13x10e prop
    Just under 1600 watts
    7.5 to 8 min flight time
    10,800 rpm static

    My scorpion is GREAT. Absolutely no issues. It is the perfect motor for this plane. For earlier, smaller designs, such as the P-7 the smaller 4020-8 is a great motor on 5s.

    Flies exactly like it would with a YS 61 and pipe on it except the power curve is a little different; you have to get on the throttle a little earlier coming out of menuvers such at the reverse outside loop. It is smooth and works great for me. No mess, no fuss, no tuning.

    A ground-up electric could be built with this power system and kept under 9 lbs. There just isnt the need for structure with smooth E-Power.

    The guys Ifly with rib me about "Electrifying" a classic. But they have seen it fly and respect that it is the right answer for me. We have a good time with this....See picture.

    My two-cents,

    Doug
    aka Fatherof4
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  12. #12
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    RE: Replacement for displacement.

    I went the short stroke 60 route with the electric component choices in my Phoenix 5 I fly in SPA.
    Rimfire 60 650kv motor
    HK redbrick 70amp opto
    Zippy 5000mah 40C 6S packs

    I'm right at the 1400watt limit for SPA, and I'm turning an APC 11x7 around 14.1-2krpm. Has more than enough power for Expert.



  13. #13
    doxilia's Avatar
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    RE: Replacement for displacement.


    ORIGINAL: bjr_93tz

    Hi David,

    The trouble is that I'm giving away away so much efficiency running an 11'' prop but you get nice smooth turbine like power. The old .75 I'm used to is rated to put out about 2.4hp. 1300W just isn't going to cut the mustard at 100mph, BUT at 60-70MPH with a 12-13'' diameter prop 1300W is in the ballpark. The math says 8+lbs of thrust at 100mph = 2+horsepower.

    I morally object to people flying a classic with a 14'' prop turning in the sub 10's , it'd be like pulling the V-twin 2-stroke out of my TZ and replacing it with a 650cc single 4-stroke.
    I think you hit it on the head. Your efficiency is falling off the steep end of the curve by using props that are way too small for the KV rating of the motors. I also agree that 1300W isn't going to give you 100 mph performance especially on 12" props. The figures I offered were really in a way of perspective in terms of achieving power with different types of motors under what I'd consider "ideal fuel" configurations. Just as turning 14" props on pre-turnaround classics is objectionable, loading up the same classic with 10 or 12 cells of lithium power is a bit much. You mentioned 10s 4Ah - that much battery has got to weigh a ton (~42 oz?). One winds up having to lug around close to 9 lbs of classic (or more on 12s) with a 10 or 11" prop expecting blistering performance. It might work in a dive but level flight and uplines will be ho-hum at best. Keep the amount of power roughly the same (although it doesn't need to be that high), reduce the weight by 20% (a 7.5 lb Curare is doable with the right construction and finish - I believe the Austrian ARF comes in at 7.5 all up) and then one might begin to approach ballistic performance.

    The Scorpion on 10S (it's rated for 12S), pulling about 65A static with the 11x9 gave very similiar performance to the .75 two stroke and honestly up to about 9000rpm was very smooth but when pushed beyond that the whole thing got very bendy. I was running glow props on it as well, not the floppy E props. When you compare how solid the front end of a glow motor is to an electric you can see it's asking a lot from it. But it's all experimentation. The 8mm shaft wasn't flexing from what we could see but the ''spigot'' (for want of a better word) that the bearinges and stator are mounted into. On the rear mount arrangement my friend was using, you could grab the prop and bend it from side to side watching the can flex around in relation to the stator.
    From your figures, you're pushing in excess of 2400W nominal on very low kV motors! At that power rating and kV with rapid transitions to ~13K you may be getting close to prop tip cavitation. After a few flights do your prop tips look a little funky? If you want to turn a turbine, you've got to up that kV. The motor needs to be more "elastic". You will not find a single ducted fan motor in the 400 kV (let alone 330 kV!) configuration. Many an EDF is turned by inrunners capable of 2000+ kV.

    Devin wanted to build a P8 and push it to 200 mph. It was realized that this was extremely difficult to achieve on a classic design with e-power but he says he's reached 180 mph. I can't recall what his model weighs and his airfoil might be thinner than design but he's simply turning a 4030-880 kV motor on 6s with a 10x10 prop. That is a motor that is designed to turn 19.5K nominal unloaded. I don't know what rpm's he's turning on the 10x10 but they are likely in the ~14-15K range. The motor is short, bearing supported in the rear of the can with no shaft extension, is front mounted (ideally with an X-mount but I don't know) and has a max current rating of 90A. So he is still producing the similar 2000W that your Scorpions are (22.2Vx90A) at a power loading of ~250 W/lb with an 8 lb model. The weight is of course achieved with the 6s pack which is ~60% the weight of a 10s pack or 50% of a 12s pack (assuming the same capacity).

    Within the Scorpion brand, I think that if we want ballistic performance from 10-11" props on trike configurations, we might be better off targeting motors such as the HKIII-4025-890kV (6mm). There's a motor with a stator of only 25 mm capable of producing 2700W/95A continuous. Put an 11x7 on it with 6s and expect ~16K and ~2100W on a motor that weighs 10 oz and a battery that weighs 26 oz (2.5 lbs of power plant equivalent to 16 oz of fuel and a piped YS 60 FR). Because the motor is that much more elastic, it will transition smoothly to those rpm's without gross pressure differentials and resulting cavitation.

    Don't let mine and my friends not-so-positive experience with the Scorpion outrunners put you off from experimenting. His was a S-4035-330 he intended to run ''rear mounted'' on 12S in a Falcon 120 but it was too bendy for that. He turned it around to a front mount, with a 10mm ply box around it with external rear bearing support and it's bench testing a lot better. Both motors up to about 9k were fine but started getting out of shape after that. I'm beginning to think a ''typical'' outrunner design doesn't scale well, just like we don't see too many .15+ sized engines based around the design of a Cox .049...
    The above are just my thoughts and experimentation is definitely the key but I feel that one might do better on lighter configurations with smaller motors at higher KV's if one is aiming for equivalent '80's setups. If on the other hand, we're talking about modified late 80's, early 90's conventional gear models designed for 12-13" props on Hanno/YS LS like power, then using ~550KV motors is the way to go. If there is a black art to the electric equation, I think it is in finding the sweet spot between prop desired, motor KV and motor geometry. Shorter is better with outrunners to prevent flexing and ideally using 8 mm shafts on the 12-13" props while 6 mm shafts ought to work on the 10-11" props provided the can is short enough and the bearings are stout.

    Man! Writing about e-power is akin to typing science class solutions - it's hard to keep track of all the darn units and abbreviations!

    David

  14. #14
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    RE: Replacement for displacement.

    ORIGINAL: 80sPattern

    My scorpion is GREAT.* Absolutely no issues.* It is the perfect motor for this plane.* For earlier, smaller designs, such as the P-7 the smaller 4020-8 is a great motor on 5s.

    Doug
    aka Fatherof4
    As Doug puts it, the Scorpion S-4020-8 (790KV) on 5s is the Scorpion SPA choice for 1400W of power (80A/5s max). It won't get the ballistic blistering speed performance you guys down under are looking for but it is light and well suited to SPA. For CPA on smaller retract designs, the HKIII 4025-890KV motor I mentioned above ought to be interesting to try.

    The Rimfire 60 being a 650KV unit, is that much better on 6s than say the E-Flite 60 which is a 400KV unit.

    Greg, the Hyperion you mention sounds like it is right in the correct geometry and elasticity for 11x9 props at ~11.5K and ~1500W. I'd up the KV a tad if you want better performance on 11" props. By the way, they're made by Scorpion...

    David

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    RE: Replacement for displacement.

    Hi David,

    I was hoping to take the higher voltage, lower current route. Actually my test flight was with a 4Ah and 5.35AH pack in series [X(] for proof of concept before getting a couple of 5S ~3Ah packs if it all worked out. Oh yeah, you're right about it weighting a ton, it took a couple of landing approaches to get the final turn lined up with the runway as it was running wide in the slow turns. But in the air felt ok.

    I was just very disappointed the $200 scorpion motor couldn't just bolt in and work properly, but I was very happy with the flight performance however dealing with the bad vibes at certain rpm needs some nutting out. The magnet/stator arrangement for that particular motor results in very heavy cogging and I'm tempted to believe that's part of the issue as well. Even with the prop off you can feel vibes kicking in at different rpm.

    All good fun experimenting with a 20+ year old, oil soaked airframe but it was enough to convince me that building a brand new one purpose built for electric is the better way to go. Every time I visit the Tower Hobbies website I see a 75AX staring at me and I'm pretty sure it'd bring my Curare back to life at the correct weight with less fuss but I think I'm done with IC from now on......

  16. #16

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    RE: Replacement for displacement.

    BJ,

    I"front"mounted my scorpion as you can see in this picture. Ireally do not think that is the problem that you are having but Ithought Iwould share. Isimply created a "front" firewall and epoxied it in. Itapped the "X" mount provided by Scorpion and bolted thru the new firewall. Again, with the smooth running Scorpion, you do not need much structure. Iremoved almost all of the previous rear IC firewall to allow airflow and reduce weight.

    It is good to see others experimenting with other ideas. Can you share some picutres of your plane?

    Doug

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  17. #17
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    RE: Replacement for displacement.

    ORIGINAL: bjr_93tz

    Hi David,

    I was hoping to take the higher voltage, lower current route. Actually my test flight was with a 4Ah and 5.35AH pack in series [X(] for proof of concept before getting a couple of 5S ~3Ah packs if it all worked out. Oh yeah, you're right about it weighting a ton, it took a couple of landing approaches to get the final turn lined up with the runway as it was running wide in the slow turns. But in the air felt ok.
    I see where you're coming from but on trike classics, 6s is the high V/low A route. Low V/high A would be the 5s route. Going to 12s is really only a sensible proposition on 14 lb+ models which are designed for 1.6/2.1 glow or 50cc gas setups. Equivalently, the 2m current pattern designs are running 10s setups but on much bigger motors with 20" props!

    I was just very disappointed the $200 scorpion motor couldn't just bolt in and work properly, but I was very happy with the flight performance however dealing with the bad vibes at certain rpm needs some nutting out. The magnet/stator arrangement for that particular motor results in very heavy cogging and I'm tempted to believe that's part of the issue as well. Even with the prop off you can feel vibes kicking in at different rpm.
    I think the motor probably does just bolt in and work fine but it is a torquer and not designed for our 11" props. You're overdriving it on too small a load. Bring the cell count down to 6s or 8s and a 15-16" prop and it will do fine - just not what you're looking for. If the motor doesn't turn smoothly unloaded there is a chance something is loose or unbalanced.

    All good fun experimenting with a 20+ year old, oil soaked airframe but it was enough to convince me that building a brand new one purpose built for electric is the better way to go. Every time I visit the Tower Hobbies website I see a 75AX staring at me and I'm pretty sure it'd bring my Curare back to life at the correct weight with less fuss but I think I'm done with IC from now on......
    Putting a 75 or 95 AX porker on a Curare is sort of similar to the electric 300-400KV motors we're talking about. Take 4 oz of fuel out and install a 55 AX and it might be surprising. I find even the 65AX to be a bit too much fat but it's not hugely different weight wise to the vintage 61's. Hanno has approved the 55AX on the new ARF he's been involved with. I think it speaks volumes about light modern airframe power plants.

    David

  18. #18

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    RE: Replacement for displacement.

    Hi Doug, Nice picture, I'll try to load up a couple from my install when I get home.

    Mine (and my friend's) had bad vibes over about 9krpm even when bench mounted to a piece of 16mm thick MDF. I'll make up a longer shaft and mount a bearing in the old firewall for rear support. To be honest, my motor turning 15-16k on 12S in a heli is probably where it would be happiest, not running up and down the rpm range with a gyroscope hanging off the front. But hey, I've been one of the unlucky few who's even had troubles with a YS motor and they're "top shelf" too.


    David I know where your coming from, lighter flys better. With modern gear and construction you can knock out some weight and it's a circular thing.

    less weight = smaller motor=less fuel=lighter weight=better performance

    But anyway, I'm waffling off topic and diluting the good replies to Greg's original post.

    EDIT: Actually when looking at eness76-RCU's numbers we're fairly similiar He's got 6S 5Ah pack vs my intended 10s 3Ah (same total energy capacity) and his 650Kv on 6S works out to be about 390kv on 10S (mine's 400Kv) and I'm down about 1k rpm static with 2 extra inches of pitch...

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    RE: Replacement for displacement.

    No no, by all means, dilute away. It's all good information.

    I think I might reserve my decision on what to wedge in the front, once I get it back and figure out: a) what sort of ground clearance I have, and b) how much room I have in the cowling.

    The rest will fall in line I think, including no of cells, capacity etc

    It's all up for grabs!
    Go knife edge your cub!

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    RE: Replacement for displacement.


    ORIGINAL: bjr_93tz
    David I know where your coming from, lighter flys better. With modern gear and construction you can knock out some weight and it's a circular thing.

    less weight = smaller motor=less fuel=lighter weight=better performance
    I don't quite look at it that way although what you say is true. We all know that light models are desirable. I look at it from a prop size and rpm standpoint in relation to the type of model I want to power. Helis, EDF's, pylon and classics benefit from elastic high KV motors. 3D, War birds, scale and modern F3A models benefit from the opposite. Are we looking for prop torque or pitch speed? The two require different motor types.

    EDIT: Actually when looking at eness76-RCU's numbers we're fairly similiar He's got 6S 5Ah pack vs my intended 10s 3Ah (same total energy capacity) and his 650Kv on 6S works out to be about 390kv on 10S (mine's 400Kv) and I'm down about 1k rpm static with 2 extra inches of pitch...
    Without wanting to continue harping on the subject, what you say is true but it's also akin to saying "all roads lead to Rome". The issue is whether one wants to take the St Bernard tunnel or cross the Alps - they're two very different approaches. Power is power but it's how it's wielded that matters...

    David

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    RE: Replacement for displacement.


    ORIGINAL: doxilia


    ORIGINAL: bjr_93tz
    David I know where your coming from, lighter flys better. With modern gear and construction you can knock out some weight and it's a circular thing.

    less weight = smaller motor=less fuel=lighter weight=better performance
    I don't quite look at it that way although what you say is true. We all know that light models are desirable. I look at it from a prop size and rpm standpoint in relation to the type of model I want to power. Helis, EDF's, pylon and classics benefit from elastic high KV motors. 3D, War birds, scale and modern F3A models benefit from the opposite. Are we looking for prop torque or pitch speed? The two require different motor types.

    EDIT: Actually when looking at eness76-RCU's numbers we're fairly similiar He's got 6S 5Ah pack vs my intended 10s 3Ah (same total energy capacity) and his 650Kv on 6S works out to be about 390kv on 10S (mine's 400Kv) and I'm down about 1k rpm static with 2 extra inches of pitch...
    Without wanting to continue harping on the subject, what you say is true but it's also akin to saying ''all roads lead to Rome''. The issue is whether one wants to take the St Bernard tunnel or cross the Alps - they're two very different approaches. Power is power but it's how it's wielded that matters...

    David
    Give me a Ferrari and I'll take the alps, give me a Trabant and I'll go the tunnel.

    Go knife edge your cub!

  22. #22

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    RE: Replacement for displacement.

    Hi David,

    when you say "elastic" in relation to higher KV motors, is that meaning that available power is spread over a wider RPM range and they'd tend to be a little less self-governing with regard to holding rpm as the load varies?

    Not wanting to harp on it either, but I think some of the older guys forget just what kind of tiger they had by the tail back then with full house, piped F3A ship. Flying around at 60-70mph with 1400w in a fixed gear taildragger they'd be better off slapping their Curare stickers on a WindS 50e.

    Hey Greg, would you still prefer that Ferrari if it had my Ford XF 6cyl 250 crossflow in it? Even with a sports exhaust I don't think we'd be getting the full Ferrari experience

    I hope nobody takes offense at my comments as it's clear that 6S, with the system specs that others have posted is what's doing the business in competition today and is the preferred way to go.

    Cheers
    Brett

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    RE: Replacement for displacement.

    I have seen a couple times in this thread that 5S is mentioned as the preferred SPA setup, but I can tell you as an active SPA flyer and electric flyer, I have never seen a 5S setup in SPA. Everybody is running 6S. Most guys are using that 6S with lower Kv motors to spin props more comparable with a 4s 91, but I made my propulsion target more along the lines of what the airplane was designed for. With regard to the extra weight of 6s over 5s, my Phoenix is 6lbs-4.5oz up all battery in and ready to fly. If I built another I'd probably shoot for 7lbs to handle turbulent air a little better. When choosing my setup I wanted my Phoenix to fly in the same flight envelope as our old Phoenixes did in the old days. I can assure you it is no WindS with Curare decals, and I doubt it sees 60mph even on the uplines. It may have fixed gear and be a taildragger, but it flies like a classic patternship was designed to. Jamie Strong could attest to that. At the Masters in Chattanooga he was flying a Dirty Birdy with a Nova Rossi on it and my Phoenix was faster.

  24. #24

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    RE: Replacement for displacement.


    ORIGINAL: eness76-RCU

    I have seen a couple times in this thread that 5S is mentioned as the preferred SPA setup, but I can tell you as an active SPA flyer and electric flyer, I have never seen a 5S setup in SPA. Everybody is running 6S. Most guys are using that 6S with lower Kv motors to spin props more comparable with a 4s 91, but I made my propulsion target more along the lines of what the airplane was designed for. With regard to the extra weight of 6s over 5s, my Phoenix is 6lbs-4.5oz up all battery in and ready to fly. If I built another I'd probably shoot for 7lbs to handle turbulent air a little better. When choosing my setup I wanted my Phoenix to fly in the same flight envelope as our old Phoenixes did in the old days. I can assure you it is no WindS with Curare decals, and I doubt it sees 60mph even on the uplines. It may have fixed gear and be a taildragger, but it flies like a classic patternship was designed to. Jamie Strong could attest to that. At the Masters in Chattanooga he was flying a Dirty Birdy with a Nova Rossi on it and my Phoenix was faster.
    Eness,

    Iappreciate the info you have provided. Iam sure your P-5 is plenty fast. Ithink it is great that you tried to make your P-5 fly like it has a 60 in it. As you stated, you are being true to Don Lowe's design while using a modern power plant. Iam a believer is converting to E-Power but staying true to the design. My C4e flies exactly like it would ifit had a YS 61 in it which is was designed around. Your low weight is great advantage that allows you to have plenty of power while staying within the SPA guidelines. Iwould be happier with my C4e if Icould drop a pound. However, the Conqust IV is a BIG airplane, compare it to the P-7's in the photo below.


    BJR,

    Keep the comments coming. Ithink this conversation is really healthy. When Idecided to convert my C4e in 2011 there really wasn't much on the web to guide me. (Ihave to admit, that was part of the challenge)


    Rendegade,

    Thanks for starting this thread and providing us a place to discuss E-Power in Classics.

    Doug


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    RE: Replacement for displacement.

    I think there's two schools of thought.

    One school is trying to replicate the original characteristics of the designs and their power plants, the other school is trying to make the most efficient use of what's allowed within competition rules to maximise their flying performance. I've got my 2M ship for flying pattern but still enjoy digging the old girls out for some sporting around..

    I think it's great the variety of electric options exist because it's win-win for everyone.


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