Prop for SS1 on 4S lipos ?

[G Doggett]

I am about to finally throw away the last of my damn NiMh cells in our entry level 700 powered restricted hydro and offshore classes, and replace them with 4S lipos.
I have a Campbell Shovel and a BBY Charger (Oval Master 26 variation).
I seem to remember that 30-40 amps is about the safe limit for these brushed motors, and I will still be using the good old Astro ESC which has a max rating of 50 amps.
Have any of you guys got experience with this combination, and can recommend a suitable prop as a starting point ?
I am guessing about an X442.
Graham.

[GregS]

When I switched to 4S lipo from 12 NiMH last year in 700 powered LSH and LSO I used the same props (X642, M445). I didn't find that the batteries made much difference with the 700's as long as the NiMH were fairly new and in good shape. This is probably because the NiMH can easily supply the relatively low current demand. The biggest difference was in the handling of the boats. The light batteries and heavy motor put them out of balance.

Greg

[Jeff Wohlt]

I ran a 545 on my MM with 700 and it was excellent. Not sure about the hydro but a 642 should be good and maybe more depending on time you need.

[Scott T]

Hi Graham!

Before I sold my Cabover I gave it a couple of runs on lipo. Used the same props as with NiMH, and located the cells to give the same CG. It was a rocket, you'll enjoy it

Scott

[crabstick]

Hey Graham, the Astro 207d (which i recall you have) can do 75 amps continuous. and up to 40 cells. I still have mine. I would be more worried about the 700

Something like this would be useful tho :

http://www.rchelis.co.nz/product_info.php?products_id=495

Because the Astro has no low voltage cutoff. you can mount the Low Voltage warning led outside the hull perhaps these LED's are so bright you can see them at 80feet out, 50 feet high on the heli, saves cooking lipos anyhoo.

I can get the schematic off the guy who makes them if you like ? the I/C used is hard to find though, I made one for 3s for my Trex helicopter.As the Astro has no low voltage cutoff. you can mount the Low Voltage warning led outside the hull perhaps

m445 might be a good prop to try , should be about the 40 amp mark

[z400]

What nimh cells are you wanting to throw away?

i might be interested in them.

[G Doggett]

Hi Matt.
Yes it is a 207D, so it should handle the current OK, the weak link is the 700 motor which as we know will fry if asked to deliver too much.
Both of my SS1 motors are still in good nick so I figure I might as well keep using them and upgrade the battery supply to get some more life out of these two boats.
A low voltage warning device is something I am thinking about, as although when racing the time and laps are always calculated, when testing or playing it is possible to get carried away and forget just how long you have been running.
I have already modified Miss Bardahl to take the lipos mounted much further forward, and even the receiver batteries are now up front to keep the same c/g.
Next on the operating table is Short Circuit.
Graham.

[G Doggett]

What nimh cells are you wanting to throw away?

i might be interested in them.

Hi Z400.
'Throw away' was more a figure of speech.
I will probably sell them locally with the charger to a fellow club member.
Besides the freight from New Zealand to USA is a killer.
If you are still interested they are 2 x 6 cell Epower 4500s and 2 X 6 cell Duratrax DTX 4200s, all about a year old.
Graham.

[J Solinger]

I all ways run a x645 on my 700 powered stuff. You will be safe.