when will this thread be STICKY?
I'm seing some newbies going away from this base, no good for them IMO!
Fast Electric Addict!
when will this thread be STICKY?
I'm seing some newbies going away from this base, no good for them IMO!
Member
[QUOTE=ReddyWatts;44733]What about a spreadsheet to help users decide on a build?
"Updated" with Lipo and esc amp ratings. There are too many variables for this to be exact for all of the different hull and motor loads. Many setups will fall outside of this general data spreadsheet. Just hope this gives you a better understanding of FE for designing successful setups.
--hull size /--------Cells---------/ ----Motor Kv----- / -------Prop Size------/---Type ESC---/-BEC-/ESC Amp Rating
17”- 24” / 2s LiPo or 6 cell NiMh / 5500 -3200Kv / 30mm - 40mm Diam. / Low Voltage / Avail. / 120 amp
20"-27" / 3s LiPo or 8 cell NiMh / 3500-2500kv / 35mm – 42mm Diam. / Low Voltage / Avail. / 120 amp
24”-29” / 4s LiPo or 12 cell NiMh /2650-1600Kv /37mm - 46mm Diam. / Low Voltage / Avail~Disc / 120-240 amp
26”-32" / 6s LiPo or 18 cell NiMh /1800-1100Kv /40mm - 52mm Diam. / Low or High / Disc. / 120-180-240 amp
30"- 36" / 8s LiPo or 24 cell NiMh / 1350-800Kv /45mm – 55mm Diam. / High Voltage / N/A / 180-240 amp
34" - 42" / 10s LiPo or 30 cell NiMh / 1100-600Kv /47mm + Diameter / High Voltage / N/A / 180-240 amp
38" - 46" / 12s LiPo or 36 cell NiMh / 900-550Kv / 50mm + Diameter / High Voltage / N/A / 240 amp
Does this table also hold true for dual-drive setups?
Fast Electric Addict!
Lots of talk about 3S lipos in here. Unfortunately, the dolts at IMPBA have deigned 3S lipos as non-existent, having 2S, 4S, etc. classes.
This is really stupid! There are so many RTR 3S lipo boats out there they are totally ignoring a segment of the market and eliminating newbies that would like to race!
Fast Electric Addict!
this doesn't make any sense to me. Your spreadsheet says to use a 52mm diameter prop on a 4S 1800KV motor! NO WAY! You'll burn it up!
Fast Electric Addict!
Typically 6S is 6S2P or two 6S packs in parallel. Two 3S in series will not yield enough mAh generally.
Originally Posted by sdartt
When you call for a 26 to 32 inch hull using 6 cell LiPo's, does that mean 2 packs with 3 LiPo's each. Thanks for the reply!
Mini Cat Racing USA
www.minicatracingusa.com
Fast Electric Addict!
This was an on going project. I would update the chart as users gave suggestions. I have not been able to update any of this since it was moved to this section.
ReddyWatts fleet photo
M1 Supercat - Neu 1527 1Y, 8s / Mean Machine- Feigao 580, 8s, 120 HV esc
Mean Machine - Feigao 540 14XL, 8s, 100 amp HV esc, X537/3
Administrator
Readdy's right. I kinda put a strange hold on him when I started this area. I hope thats somewhat resolved now.
Steven Vaccaro
Where Racing on a Budget is a Reality!
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Nevermind
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Member
There appears to be a bit of information directly taken from what I had written on rcuniverse several months ago.
Here is a direct link to the original information.
http://www.rcuniverse.com/forum/m_7603257/tm.htm
Even with the information available, I still get one pm per week asking why my power system failed resulting in burned electronics. People still are choosing motors way outside the kv range listed and props that are far too large for the application. Most are new boaters trying discover FE, not trying to make a rocket on water.
My advice is somewhere it should be stressed that if one does not know which prop or motor to select for their application PM someone who can help out.
I have designed many excel spread sheets to calculated a starting prop diameter based on weight of motor, diameter, length, boat type, and kv. It is near impossible for them to work well for every combination. My point is, experience might be the best starting point for a new boater to selecting a power system.
In most cases yes it would also hold true for dual drive set ups.Does this table also hold true for dual-drive setups?
Not my spread sheet but I'll still chime in since it was not answeredthis doesn't make any sense to me. Your spreadsheet says to use a 52mm diameter prop on a 4S 1800KV motor! NO WAY! You'll burn it up!
4s 1800kv motor is a very vague description. You are missing so many other variables. For example If you had an 1800kv S can motor it would not be too happy on a 52mm prop. If you had an 1800 kv motor in a 1521 NEU size, it would handle it with absolutely no problem and would NOT burn up.
Ryan
Fast Electric Addict!
Thanks for the idea and starting point for this spreadsheet. I have tried to stress that users start with the small props and work their way up to the desired setup. FE setups are not an exact science, there are just to many variables.
ReddyWatts fleet photo
M1 Supercat - Neu 1527 1Y, 8s / Mean Machine- Feigao 580, 8s, 120 HV esc
Mean Machine - Feigao 540 14XL, 8s, 100 amp HV esc, X537/3
Fast Electric Adict!
[QUOTE=ryan_t888;86608]There appears to be a bit of information directly taken from what I had written on rcuniverse several months ago.
Here is a direct link to the original information.
http://www.rcuniverse.com/forum/m_7603257/tm.htm
Even with the information available, I still get one pm per week asking why my power system failed resulting in burned electronics. People still are choosing motors way outside the kv range listed and props that are far too large for the application. Most are new boaters trying discover FE, not trying to make a rocket on water.
My advice is somewhere it should be stressed that if one does not know which prop or motor to select for their application PM someone who can help out.
Response
The problem is rcuniverse is not a good source of info for FE boat information and as you state and my largest concern..newbies burning up their stuff with bogus information. Tell them to join OSE or RRR forums and even then have caution to some advise espicially on RTR boats from newbies
Douggie
Senior Member
This is great info. However I cant realy make my decision as my boat is slightly in the larger end of the scale.
I have a home made 67" Epoxi V hull.
I originaly designed this hull for competition in 35cc gas class.
However I have run it with a Quickdraw 25cc HT engine. It runs great with this engine. It runs 58-59mph in light chop with a stock 7018/3 prop.
Rpm is apr. 16800rpm. Weight with fuel is 11 kg or 24 pounds.
With more prop testing and tweeking I am confident I can get it past 60.
The Quickdraw is only 7,3HP and I would think this boat will be alot faster with a big brushless system.
The hull weighs about 11 pounds empty. However I will make a lighter one for electric setup if I decide to try that. To come down to 9 pounds will be doable I think.
I was thinking that a Lehner 3080/5-7 a Hydra HV240 and 4 pc. 5000mAH 22.2V Kokam lipo packs, 2 in paralell and 2 in series might do the trick. Starting prop 6717/3
Any thoughts and advices?
Yeah and I want to go fast
Thanks
Anbjørn
Fast Electric Addict!
ReddyWatts fleet photo
M1 Supercat - Neu 1527 1Y, 8s / Mean Machine- Feigao 580, 8s, 120 HV esc
Mean Machine - Feigao 540 14XL, 8s, 100 amp HV esc, X537/3
Senior Member
I am not sure I got more enlightened. This was a lot smaller boat than mine.
Good acceleration but the speed did not impress me.
Will I have problems powering my boat into realy high speeds with brushless?
Anbjørn
Fast Electric Addict!
Contact this guy with a private message, has lots of experience with large hulls and setups.
https://forums.offshoreelectrics.com/member.php?u=568
ReddyWatts fleet photo
M1 Supercat - Neu 1527 1Y, 8s / Mean Machine- Feigao 580, 8s, 120 HV esc
Mean Machine - Feigao 540 14XL, 8s, 100 amp HV esc, X537/3
Fast Electric Adict!
Another person on this site with big boat building experience and set up is...Peter Zicha
His only problem is he likes to eat
and not what his mamma told him to eat
Douggie
Senior Member
I'm trying to understand why the recommended RPM range is 20,000 to 40,000. Is there any explanation for what the downsides are? I expect that props that are small enough to turn at 50,000 rpms do a lot of cavitating.... Is that right? what about on the low end of the spectrum trying to drive a windmill sized prop at 10,000? Thanks.
Member
It's more difficult to get a large prop spinning at low RPM to go fast and handle well. My gasser turns 15000RPM. When I gun it during a straightaway it can literally jump to one side under prop torque. You can certainly run under 20 000RPM if desired.
The minimum size prop is 27mm. If you drive 50 000+ RPM, the size necessary will be too small in some cases to actually reliably make this setup work. Also the thrust will not be great enough to push the hull on plane. There must be a good balance between pitch speed and thrust to efficiently drive the boat ahead.
Ryan
Fast Electric Addict!
as Ryan wrote if you run below 20000rpm (I would even say 25000), the appropriate prop that will make your boat go fast will be so big that the prop torque will be a serious problem, if you run above 35-40000rpm the prop will be so small that it will gave a poor efficiency (prop slippage) can you imagine a 40" boat with a 37mm? chances are that the hull won't move at all!
That said, running efficiently above 40-50000rpm is possible, it requires oversized components and short run time (SAW).
Senior Member
Got it. Thanks guys, that's very helpful.
Senior Member
...great thread.
Senior Member
Hi there,
I think you replied to my thread about my on board Li-Po fire???
As you might know, I am new to FE and there are a few things I don't understand...
In the motor KV ratings, The speeds go from high to low i.e. 1800 - 1100 Kv???
Also, Can you explain your comment about running the motor as close to its max amps???
Thanks....
Fast Electric Addict!
Link the KV to the hull size i.e for a 2S setup, 17"-24" and 5500KV-3200KV, you would use a 5500KV motor for a 17" hull and a 3200KV motor for a 24" hull, this can be explain by the fact that under 2S a 5500Kv motor will spin a smaller prop than a 3200KV motor, too small of a prop (too small compared to the hull size) would slip a lot, i.e a 29mm prop on a 40" hull will do nothing at all.
Motor manufacturers have datasheet, i.e Feigao tells that a 540-08XL is rated for 83A you then want to use it around this value, you need a recorder to do so, (EagleTree Micro Logger)
Senior Member
Got it! Thanks buddy! :-)
Senior Member
What are "For Chart Purposes" numbers?
Member
Hey
Im after some help on what size Motor and what ESC i would need for my type of hull.
The hull iam using is a 37.5" Mono Hull which is 11" wide, Iam wanting it to be brushless and iam wanting to at least get about 10 minutes out of a battery. I do want this boat to be quick also and specially do want it to run for that 10 Minutes.
So what Brushless motor will i need, Feigao preferably?
What ESC will i need, dont want something to extreme and expensive?
What lipos, size, Volts etc, should i run 2x Lipos in parallel?
What size prop do i need?
@SiestaKey.calm
A 580 12L, Turnigy 180 esc, 2 x 6S 5000Mah packs and a X450 should get you where you want to go, without breaking the bank (completely).
All the best,
Ray
Member
The 580 12L
Whats that equivalent to the Feigao?
@SiestaKey.calm
That is a Feigao. You are not gonna push that boat with the 540XL series with damaging the motor.
Member
Ok now i see
How would this ESC go with it, Its the last one for $159.95
http://www.rcboatbitz.com.au/
Also what brand LIPOS should i go for and how many Volts should they be?
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