large brushless cat project
05-20-2009 | 09:15 AM
#26
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From: Wellen, GERMANY
RE: large brushless cat project
Well I used hoop-ended bolts to support the drives,which i ground down to about 3mm thickness, and while popping them into the false transome they bent a little bit....leading me to wonder if they'll take the stress of all that torque...in any case we'll see. I just found a relatively cheap source of stinger struts, which i'm regretting not finding earlier...www.tfl-hobby.de I ordered one for a micro mogli i'm building - arrived the next day!!!! and at 19EUR - it's dirt cheap....
Another alternative is using unadulterated hoop-ended bolts. They won't look so nice...but well I don't think it really matters anyway. i think i posted some close-up pics on the HPR-cat thread....remember Dayton?
anyways looking forward to a day's building - tomorrow's a holiday here - YAY!!!!
A
Another alternative is using unadulterated hoop-ended bolts. They won't look so nice...but well I don't think it really matters anyway. i think i posted some close-up pics on the HPR-cat thread....remember Dayton?
anyways looking forward to a day's building - tomorrow's a holiday here - YAY!!!!
A
05-20-2009 | 04:44 PM
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From: Auckland, , NEW ZEALAND
RE: large brushless cat project
Hi Stokes, Ihate to be the bearer of badish news, but the kb 45 8xl doesnt spin that fast on 4S, I am running a single one in a 35 inch cat, so far have only gone about 42mph or so, with an M447, I spent the night polishing a x450 to try today, so will see how it goes. you will have to run MONSTER props to get any decent speed on 4s, The do have insane torque though and make my cat wheelstand if i punch it out of the hole!
05-21-2009 | 12:59 AM
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From: Wellen, GERMANY
RE: large brushless cat project
hmmmm...well badish news it is not. I have 47mm props and also 51mm props, so i'm hoping that with two of the monsters they should get the thing going... they are the L cans not the XLs, with 1800kv. I was imagining that 1800kv x 14.4v = 25920 RPM. yes i should have factored in that these things are inefficient....hmmmm you're right. Well then I have a problem....I have 2 x 4s or 2 x 3s. And in my books that can only mean that I'll be running:
2 x 4s or
2 x 3s or
2 x 7s....this will surely spell disaster for my side of the world, sending bits of fibreglass, motor and drive parts into deep space. And quite honestly I don't feel like being banned from the local pond. Ok perhaps i'll send for a couple of 2s packs from UH. That way I can run 2 x 4s + 2 x 2s = 2 x 6s. or else 2 x 3s + 1 x 4s + 1 x 2s...that should do the trick...47mph is still way faster than my driving skills will allow, so well...maybe it's a good thing for the moment.
Thanks for chiming in...
A
2 x 4s or
2 x 3s or
2 x 7s....this will surely spell disaster for my side of the world, sending bits of fibreglass, motor and drive parts into deep space. And quite honestly I don't feel like being banned from the local pond. Ok perhaps i'll send for a couple of 2s packs from UH. That way I can run 2 x 4s + 2 x 2s = 2 x 6s. or else 2 x 3s + 1 x 4s + 1 x 2s...that should do the trick...47mph is still way faster than my driving skills will allow, so well...maybe it's a good thing for the moment.
Thanks for chiming in...
A
05-21-2009 | 05:19 PM
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From: Auckland, , NEW ZEALAND
RE: large brushless cat project
Also an update, I ran an x450 at 73kmh on gps (not very fast IMO) on the KB458xl...
lipos got pretty hot, id say that the L might be less torquey, but i still think 5 or 6s will be the go!
also your calculations are for free running rpms ?
when i run my kb through the ESC's usb program, it shows me 21000 rpm on the rev counter.
lipos got pretty hot, id say that the L might be less torquey, but i still think 5 or 6s will be the go!
also your calculations are for free running rpms ?
when i run my kb through the ESC's usb program, it shows me 21000 rpm on the rev counter.
05-21-2009 | 05:32 PM
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From: Wellen, GERMANY
RE: large brushless cat project
yes, not only free rpms but also 100% efficiency, which i know will be far from reality at the pond.....saving up for new lipos as from this post.
05-26-2009 | 06:55 AM
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From: Europe, HUNGARY
RE: large brushless cat project
Hi! Thanks for your reply!</p>
I've been researching about this twin cat setup of mine
I want to keep the amps low, so at a given power I must raise the volts. Less amps = less heat, less ESC muscle, but I need a HV ESC like the Turnigy 100A HV.I'm thinking more and more about 6-8S setups. Especially the KB45-12L 1400kv @ 8S = 35840 RPM</p>
We're talking about X number of series Lipos and motor KV's but what I want to know is:
What should be the target free-run RPM for a 1.1m twin motor cat? What RPM range should I consider?
After some research, I am thinking that somewhere between 30-40K, am I right?! Cause if I knew this it would help me in choosing the right motor and the number of series connected A123's.
I made some calculations with th KB L's. The XL's are too much for this boat I think, also quite heavy, so I left them out for now. Correct me if I'm wrong.
Batteries are A123's NOT lipos. I calculated ~ 3.2V / cell
KB45-8L 2300kv @ 4S = 29440
KB45-8L 2300kv @ 5S = 36800 *
KB45-8L 2300kv @ 6S = 44160
KB45-10L 1800kv @ 4S = 22040
KB45-10L 1800kv @ 5S = 28800
KB45-10L 1800kv @ 6S = 34560 *
KB45-10L 1800kv @ 7S = 40320
KB45-12L 1400kv @ 5S = 22400
KB45-12L 1400kv @ 6S = 26880
KB45-12L 1400kv @ 7S = 31360
KB45-12L 1400kv @ 8S = 35840 *
KB45-12L 1400kv @ 9S = 40320
(I marked what I think are good setups with a "*")
And here's what some people have advised me so far:
(Batts are Lipos - I calculated ~ 3.6V / cell)
Feigao 540 8XL 2084KV @ 4s = 30009
B44 on ebay 2000KV @ 6S = 43200
KB45-08L 2300kv @ 4s = 33120</p>
05-26-2009 | 07:38 AM
#34
RE: large brushless cat project
Is this a 1.1m hull? If so 1.1m = 43" (inches)
Under the assumption this is 1.1m:
You will need motors around the size ofKB-45's for a hull that large. Problem with the KB-45's is they are amp hungry.
If you wish to be conservative on current you will have to run 10s voltage. Perhaps 10-12s A123 cells per motor. You should have minimum 4000mAh if that means 2P foryour particularA123 cells.
Also running the RPM's around 30 000 unloaded would be a good start. 20000-25000 at the prop would be decent.
Just for comparison, if this was my hull I would plan for 8-10s LiPo @ 5000mAh, run a single NEU 1527 or 2215, matched with a Hydra 180HV. This would be reliable if kept light for the 1527, and propped conservatively. It would still provide well over 50mph of fun.
Ryan
Under the assumption this is 1.1m:
You will need motors around the size ofKB-45's for a hull that large. Problem with the KB-45's is they are amp hungry.
If you wish to be conservative on current you will have to run 10s voltage. Perhaps 10-12s A123 cells per motor. You should have minimum 4000mAh if that means 2P foryour particularA123 cells.
Also running the RPM's around 30 000 unloaded would be a good start. 20000-25000 at the prop would be decent.
Just for comparison, if this was my hull I would plan for 8-10s LiPo @ 5000mAh, run a single NEU 1527 or 2215, matched with a Hydra 180HV. This would be reliable if kept light for the 1527, and propped conservatively. It would still provide well over 50mph of fun.
Ryan
05-26-2009 | 12:55 PM
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From: Europe, HUNGARY
RE: large brushless cat project
Hi Ryan!
Yes, you're right, as others told me as well, a single motor setup would be better. But you know, I want this boat to be somewhat scale looking, and I've never had a twin powered boat before.
I'm not building this boat for racing purposes, and if the KB's can make this boat run around 50-60MPH, I'll be VERY satisfied with it.
I know the NEU and the Hydra would be a very good setup, but I don't have the money for it.
Another question, what is the difference between the KB 45 XL's and the L's current wise? Would the Turnigy 100A HV handle the XL's as well? Is it worth going with the XL's considerin they're heavier than the L's?
Yes, you're right, as others told me as well, a single motor setup would be better. But you know, I want this boat to be somewhat scale looking, and I've never had a twin powered boat before.
I'm not building this boat for racing purposes, and if the KB's can make this boat run around 50-60MPH, I'll be VERY satisfied with it.
I know the NEU and the Hydra would be a very good setup, but I don't have the money for it.
Another question, what is the difference between the KB 45 XL's and the L's current wise? Would the Turnigy 100A HV handle the XL's as well? Is it worth going with the XL's considerin they're heavier than the L's?
05-26-2009 | 01:01 PM
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From: Wellen, GERMANY
RE: large brushless cat project
my argument exactly for the twin setup. I really wanted the scale look and twin drives really do suit cats this size no? In any case, probably in the end it'll be almost as expensive as going with one good motor and ESC...remember - you're gonna need stingers, counter rotating flexishafts, props, couplings etc etc, not to mention motors, cooling systems and ESCs...I know because i had to go through this. But if you're doing what you want - then top man, go for it.....
05-26-2009 | 01:16 PM
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From: Frederick, CO
RE: large brushless cat project
ORIGINAL: norbique
Hi! Thanks for your reply!</p>
I've been researching about this twin cat setup of mine I want to keep the amps low, so at a given power I must raise the volts. Less amps = less heat, less ESC muscle, but I need a HV ESC like the Turnigy 100A HV.
I'm thinking more and more about 6-8S setups. Especially the KB45-12L 1400kv @ 8S = 35840 RPM</p>
We're talking about X number of series Lipos and motor KV's but what I want to know is:
What should be the target free-run RPM for a 1.1m twin motor cat? What RPM range should I consider?
After some research, I am thinking that somewhere between 30-40K, am I right?! Cause if I knew this it would help me in choosing the right motor and the number of series connected A123's.
I made some calculations with th KB L's. The XL's are too much for this boat I think, also quite heavy, so I left them out for now. Correct me if I'm wrong.
Batteries are A123's NOT lipos. I calculated ~ 3.2V / cell
KB45-8L 2300kv @ 4S = 29440
KB45-8L 2300kv @ 5S = 36800 *
KB45-8L 2300kv @ 6S = 44160
KB45-10L 1800kv @ 4S = 22040
KB45-10L 1800kv @ 5S = 28800
KB45-10L 1800kv @ 6S = 34560 *
KB45-10L 1800kv @ 7S = 40320
KB45-12L 1400kv @ 5S = 22400
KB45-12L 1400kv @ 6S = 26880
KB45-12L 1400kv @ 7S = 31360
KB45-12L 1400kv @ 8S = 35840 *
KB45-12L 1400kv @ 9S = 40320
(I marked what I think are good setups with a "*")
And here's what some people have advised me so far:
(Batts are Lipos - I calculated ~ 3.6V / cell)
Feigao 540 8XL 2084KV @ 4s = 30009
B44 on ebay 2000KV @ 6S = 43200
KB45-08L 2300kv @ 4s = 33120</p>
Hi! Thanks for your reply!</p>
I've been researching about this twin cat setup of mine
I want to keep the amps low, so at a given power I must raise the volts. Less amps = less heat, less ESC muscle, but I need a HV ESC like the Turnigy 100A HV.I'm thinking more and more about 6-8S setups. Especially the KB45-12L 1400kv @ 8S = 35840 RPM</p>
We're talking about X number of series Lipos and motor KV's but what I want to know is:
What should be the target free-run RPM for a 1.1m twin motor cat? What RPM range should I consider?
After some research, I am thinking that somewhere between 30-40K, am I right?! Cause if I knew this it would help me in choosing the right motor and the number of series connected A123's.
I made some calculations with th KB L's. The XL's are too much for this boat I think, also quite heavy, so I left them out for now. Correct me if I'm wrong.
Batteries are A123's NOT lipos. I calculated ~ 3.2V / cell
KB45-8L 2300kv @ 4S = 29440
KB45-8L 2300kv @ 5S = 36800 *
KB45-8L 2300kv @ 6S = 44160
KB45-10L 1800kv @ 4S = 22040
KB45-10L 1800kv @ 5S = 28800
KB45-10L 1800kv @ 6S = 34560 *
KB45-10L 1800kv @ 7S = 40320
KB45-12L 1400kv @ 5S = 22400
KB45-12L 1400kv @ 6S = 26880
KB45-12L 1400kv @ 7S = 31360
KB45-12L 1400kv @ 8S = 35840 *
KB45-12L 1400kv @ 9S = 40320
(I marked what I think are good setups with a "*")
And here's what some people have advised me so far:
(Batts are Lipos - I calculated ~ 3.6V / cell)
Feigao 540 8XL 2084KV @ 4s = 30009
B44 on ebay 2000KV @ 6S = 43200
KB45-08L 2300kv @ 4s = 33120</p>
Looks like the same build on OFE
05-26-2009 | 02:48 PM
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From: Europe, HUNGARY
RE: large brushless cat project
Yes, I'm trying to get to as much information as possible, from more places more people, with different experiences. Thank you all for helping me!
05-27-2009 | 01:14 PM
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From: , HUNGARY
RE: large brushless cat project
Hi All</p>
I have a "small" (1,1m) MHZ Isiklar too with 2xKB45-10l (1800 kv), 2x100A esc, 2x4s 4400 li-po config. Now i'm still constructing, but i think in 2 weeks, after finishing my CNC carbon rudder, i will post datas from the first watercontact.....</p>
It's nice to find hungarian colleagues on international forums...
</p>
05-29-2009 | 02:30 AM
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From: Europe, HUNGARY
RE: large brushless cat project
Hi gelay,</p>
Yes, it's nice to see other hungarians, not a common thing.
</p>I was thinking about your setup. 4S lipo is 14.8V * 1800kv = 26640 RPM. Isn't this RPM a little low? I researched a lot, and found that I need around 35k RPM to make the boat run really fast. What do you think?
I'm still thinking wether to go for the XL KB's or stay with the L's. Or to choose a totally different motor
I'll wait till you test yours, since I'm only at the beginning of my building.</p>
05-29-2009 | 04:07 AM
#44
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From: , HUNGARY
RE: large brushless cat project
Szia norbique
Fist of all.... 4s setup is only the begining... I think the really big thing is the 6s config. You'r right that 14.8*1800=26640 Rpm can be low,....... but don't forget that i have 2 motors inside instead of 1!
I had a mono 2 boat with 4s 4400, 2300kv motor inside (34400 RPM) and with this config run about 70-80km/h.
The 4s setup is good for 70-80 km/h ....i hope..
If you have any questions, you can find me at the hungarian rcmodell forum too, with the nick: "3d"
Fist of all.... 4s setup is only the begining...
I think the really big thing is the 6s config. You'r right that 14.8*1800=26640 Rpm can be low,....... but don't forget that i have 2 motors inside instead of 1!I had a mono 2 boat with 4s 4400, 2300kv motor inside (34400 RPM) and with this config run about 70-80km/h.
The 4s setup is good for 70-80 km/h ....i hope..
If you have any questions, you can find me at the hungarian rcmodell forum too, with the nick: "3d"
05-29-2009 | 08:43 AM
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From: Europe, HUNGARY
RE: large brushless cat project
Hello gelay,
I know you have two motrs in the boat. I'm not saying they won't have enough power, but simply that the 4SRPM will not be enough I was guessing that's only the beginning.... At 6S it should be pretty fast.
I know you have two motrs in the boat. I'm not saying they won't have enough power, but simply that the 4SRPM will not be enough
I was guessing that's only the beginning.... At 6S it should be pretty fast.
06-01-2009 | 12:34 PM
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From: Wellen, GERMANY
RE: large brushless cat project
worked on the cat this weekend. Fabricated the motor mounts, epoxied them in. Resprayed the canopy. Mounted a new rudder, because I needed the old one for the cyclone mono (i had borrowed it for the trial fit). Installed the servo. cut the flexcables and epoxied the stuffing tubes in. I'm a bit worried about the drives i made. They still have a little play in them. I'm going to epoxy the hoops onto the outdrive for strenth. Maybe add chopped cf roving to the mix. Here are the pics.
06-02-2009 | 10:54 AM
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From: Europe, HUNGARY
RE: large brushless cat project
Very nice Stokes!</p>
They KB's look nice with those water jackets. Hope they perform well. Have you changed their bearings? I heard somewhere someonw did it as a preventive action. Are you using Graupner carbon props? What diameter?
Could you make a close-up pic of the water pick up on the bottom?</p>
06-02-2009 | 11:13 AM
#48
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From: Wellen, GERMANY
RE: large brushless cat project
hey Nor,
yes I'm using graupner props. 51mm for 4s and 47mm for higher voltages. I will use them to try and find the fastest/most reliable combination, then change to octuras with the same diameter. I'll take a few pics later of the water pickups, still need to epoxy them lightly from the bottom. I haven't changed the bearings yet, will order a set with my next shipment from OSE. In the meantime i started another project (waiting for the epoxy to dry)...how are you getting along with your build? any pics?
A
yes I'm using graupner props. 51mm for 4s and 47mm for higher voltages. I will use them to try and find the fastest/most reliable combination, then change to octuras with the same diameter. I'll take a few pics later of the water pickups, still need to epoxy them lightly from the bottom. I haven't changed the bearings yet, will order a set with my next shipment from OSE. In the meantime i started another project (waiting for the epoxy to dry)...how are you getting along with your build? any pics?
A
06-11-2009 | 12:23 AM
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From: Wellen, GERMANY
RE: large brushless cat project
Hey buddy, I'm waiting for a new 2.4ghz unit to use in the cat, I should be picking it up later on today, and also a pair of 200A ESCs. I went for the Mystery ESCS, which as they say are a good bang for the buck. Hopefulyy not the wrong kind of bang. In any case we'll see. I should be trying her out early next week. Got a new fast chicken from MBP-RC, and boy is it fast...worked feverishly all through the weekend to get it finished, and I did. But I was stupid enough to try it out in a river after heavy rain (flow was too bloody fast). When a contact on the lipo blew (i'm assuming it's a kind of inbuilt fuse from the factory), it was left dead in the water, going at about 10km/h downstream. fished it out eventually but only with a lot of swearing. In any case - lesson learnt, the cat will be sailing in a pond for the first few runs - although I got into larger boats to be able to use them in the nearby river (the Mosel).
where are you gonna run your cat? pond or river?
where are you gonna run your cat? pond or river?
