Thread Tools
Mar 22, 2020, 11:25 PM
Registered User
KiwiBoater's Avatar
Thread OP
Discussion

Whiplash 20


Hey guys I'm after some suggestions for setting up my Whiplash 20. I'm the second owner and it is the first hydroplane I have owned. It was built off scaled down plans of a Whiplash 20 and measures 74cm long. The previous owner was using it in the N2 class (2s) Specs are as follows:

Feigao 5100kv inrunner with 5.5mm Bullets between ESC and Motor
Turnigy Marine 120a ESC https://hobbyking.com/en_us/turnigy-...-boat-esc.html
CNC 1.4 pitch 32mm Propeller https://www.offshoreelectrics.com/pr...od=cnc-3214250
Two Turnigy nano tech 2s 5000mah 65-130c in parallel
XT90 connectors

I had it on the water for the first time yesterday and it took some time to get on to plane. It did perform well. Turning was sharp and smooth at WOT. However, it ran for 1:30 minutes at most before the ESC hit LVC. I lifted the lid and the ESC and Motor were very hot. Too hot for comfort. The lipos were almost dead cold. The XT90 connectors were hot. My Girlfriend managed to get a short video of it running before it cut out.

Minx Hydroplane (0 min 15 sec)


I would like to change it to run 4s. Most likely using the 2s lipos I have in series because I don't think I could fit a 4s lipo. But I don't know what motor to use and/or if I need to change the Current ESC. I do not race and have no clubs near me that do. I just want to run the hydroplane with a good setup for fun and I would like a cooler running setup. Any advice would be greatly appreciated.

KB
Sign up now
to remove ads between posts
Mar 22, 2020, 11:55 PM
Registered User
What's the size of the motor can? 28? 36? I'd go for a lower kv one on 4S. To be on the 30k Revs Id look for a 2000kv or even a 1800....keep us updated. Hope I can help
Mar 23, 2020, 12:00 AM
Fast electric boats maybe
Jeffro Bodine's Avatar
The first thing I see is the cooling lines on the motor are backwards, the inlet needs to be on the lowest end of the cooling jacket and the outlet on the highest point on the jacket , 5100kv is too much for a boat imo ,if you want 4s operation somewhere around 2000kv is great and the 120amp esc will work fine it's good to have headroom on the esc anyway.
Mar 23, 2020, 12:02 AM
Registered User
KiwiBoater's Avatar
Thread OP
I believe it is a 3650. If I do go to 4s should I be looking for a 40mm motor?
Mar 23, 2020, 12:04 AM
Fast electric boats maybe
Jeffro Bodine's Avatar
Quote:
Originally Posted by KiwiBoater
I believe it is a 3650. If I do go to 4s should I be looking for a 40mm motor?
No a 36mm can will be fine just as long its around 2000kv on 4s.
Mar 23, 2020, 12:07 AM
Registered User
KiwiBoater's Avatar
Thread OP
Thanks Jeffro. I had previously seen the half cooled water jacket problem mentioned on the forum. I tried to move the cooling jacket but It wouldn't budge. I had the water lines set up as per the first picture (inlet at lowest point, outlet at highest) Do you think the XT90 connectors will be able to handle the amps with 4s? Thanks
Mar 23, 2020, 12:09 AM
Registered User
Not a bigger size can but a Lower kv motor for sure. You a are lacking motor torque for such a big hull. Try a 3500kv and you'll see a difference.. But a 2000 around kv should work great instead. 5000its just too much for that voltage. Too many Revs with no torque. That motor is suffering and getting hot or Tired by revving and not moving that mass.
Quote:
Originally Posted by KiwiBoater
I believe it is a 3650. If I do go to 4s should I be looking for a 40mm motor?
Mar 23, 2020, 12:13 AM
Fast electric boats maybe
Jeffro Bodine's Avatar
Quote:
Originally Posted by KiwiBoater
Thanks Jeffro. I had previously seen the half cooled water jacket problem mentioned on the forum. I tried to move the cooling jacket but It wouldn't budge. I had the water lines set up as per the first picture (inlet at lowest point, outlet at highest) Do you think the XT90 connectors will be able to handle the amps with 4s? Thanks
Well you have 2 xt90s going into 1 xt90 so I say no , and I also done the math on unloaded rpm with that 5100kv motor and it's almost 43000 rpm way to much its needs around 30000 rpm .

74cm is bout 29" long same as a Aquacraft UL-1 get a SSS motor 3656 or 3660 can dim. at 2070 kv and a 40 to 42 mm 3 blade prop and have fun with it 40 or 45 mph can run all day long with that set-up and have 0 problems.
Last edited by Jeffro Bodine; Mar 23, 2020 at 12:24 AM. Reason: More to add
Mar 23, 2020, 12:25 AM
Registered User
KiwiBoater's Avatar
Thread OP
Thanks. Do you know any series connectors I can use that will be able to handle it? I tried to fit a 4s pack but it won't work so I have no choice but to use my 2s packs in series.
Mar 23, 2020, 12:38 AM
Fast electric boats maybe
Jeffro Bodine's Avatar
Quote:
Originally Posted by KiwiBoater
Thanks. Do you know any series connectors I can use that will be able to handle it? I tried to fit a 4s pack but it won't work so I have no choice but to use my 2s packs in series.
You can use those xt90 connectors but lose the adapter and wire the esc leads with a single xt90 on each wire and jump from the negative on 1 to the positive on the other to complete the circuit.

Look at a Aquacraft 4s wiring setup on UL-1 or a Motley Crue so see how to wire it up correctly.

Also it looks like the bushing is walking out of the strut too.
Last edited by Jeffro Bodine; Mar 23, 2020 at 12:46 AM. Reason: More to add
Mar 23, 2020, 12:58 AM
Registered User
KiwiBoater's Avatar
Thread OP
I found this and I see what you mean. I have some 5.5mm bullets ordered and plan to make a series connection like this. Thanks for the help guys. With the bushing walking is there a way to fix it. I thought they were designed to float? Do I need to glue it?
Last edited by KiwiBoater; Mar 23, 2020 at 01:00 AM. Reason: Saw Jeffro had added more info
Mar 23, 2020, 11:41 AM
Fast electric boats maybe
Jeffro Bodine's Avatar
Quote:
Originally Posted by KiwiBoater
I found this and I see what you mean. I have some 5.5mm bullets ordered and plan to make a series connection like this. Thanks for the help guys. With the bushing walking is there a way to fix it. I thought they were designed to float? Do I need to glue it?
Yes that's the wiring setup I was speaking about
Mar 23, 2020, 02:41 PM
RELAX. You'll live longer
785boats's Avatar
Hi there Kiwi Boater.
PM answered.

But in all my race boats & scale boats, I fit a male bullet to the negative wire of the lipo's & a female bullet to the positive wire of the lipo. The opposite on the ESC, obviously.
That way there is no need for any series harness or extra wire & connectors.
Simply plug the positive lead ov one battery into the negative lead of the other battery. The remaining leads then plug into the ESC.

Most of our club members do the same thing.

That is the most common way to use bullets.

Here's some pics.

Cheers.
Paul.
Mar 23, 2020, 05:25 PM
Registered User
KiwiBoater's Avatar
Thread OP
Thanks 785boats that's an awesome Idea.
Mar 23, 2020, 06:19 PM
RELAX. You'll live longer
785boats's Avatar
Just keep your wits about you when plugging in. Do NOT plug the positive & negative lead s of the same battery together. It's not a pretty sight.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Whiplash Sport 20 785boats Racing Boats - Electric 2 Oct 15, 2018 12:10 PM
Discussion MA Whiplash interchangeable parts? navyguy757 Fuel Heli Talk 0 Sep 22, 2018 03:42 PM
Help! atomik whiplash dropin motor HALO3 Racing Boats - Electric 2 Aug 14, 2017 02:40 PM
Help! whiplash color change Jwellmaker977 Racing Boats - Electric 51 Oct 03, 2016 06:12 AM
Discussion What do you know about Whiplash? OddJack Electric Heli Talk 9 Jun 22, 2016 12:37 AM