1/24 scale perkasa

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6 May 2014 at 08:05 #48725
CookieOld
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@cookieold
Hi All , I am building a 1/24 Perkasa ( the big one ) with a GRP hull

i am running 1 MFA 850 in the centre and 1 speed 600 at each side , as anyone used a similar setup and uses 2 off 12v 7ah sealed lead acid batterys. I get mixed answers when i ask friends this question , some say it,s fine and others say they are to heavy , Can anyone please advise me.

Many Thanks Dave
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6 May 2014 at 08:05 #2390
CookieOld
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@cookieold
Lead Acid Batterys
6 May 2014 at 08:21 #48726
Paul T
Participant
@pault84577
Hi Dave
Lead acid batteries are heavy but they also struggle to provide power quickly, ie they are great for torches but not for high demand motors.
I would suggest nicads as a more suitable and affordable option.
There are more rechargeable types available but they do come with a larger price tag.
Paul
6 May 2014 at 08:24 #48727
Gareth Jones
Participant
@garethjones79649
Hi David,

I have a fairly similar model but perhaps slightly smaller, its a 1:24 scale Elco PT boat. I stated off with three motors and a pair of 6 volt 4 ah sealed lead acid batteries in series. It was a heavy combination, but a bigger problem was that the sealed lead acid batteries do not provide sufficient current capacity. If you try to draw more than a few amps the voltage drops significantly and they will not provide enough power. I would suggest you go for either NiMh type batteries or if you want the ultimate performance LiPo batteries.

After much experimenting with various combinations I eventually ended up with a pair of Speed 700 motors and a single 11.2 volt 6 ah LiPo battery gave the best performance – very fast and a reasonable running time. For guidance it is fitted with 30 mm propellers (scale size), is 40 inches long and weighs 13 lb.

Gareth
6 May 2014 at 08:42 #48728
ashley needham
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@ashleyneedham69188
Dave. Without altering any of the running gear, I would agree with Paul T and Gareth that Nimh is the way to go. Lipo would bring benefits but only if you were to change the motors.

You will save at least 50% of the weight compared to the SLA batteries, and will get a longer run time due to being able to use most of the capacity of the batteries, as opposed to the SLA where it is not a good idea to flatten them.

Your performance will increase a fair bit due to the lesser weight. I have two MFA boats, one with twin 800`s and one with an 850, and these were set up to use a 7Ahr 12v SLA as per MFA instructions, and they both go well enough. On a 12v 5Ahr Nimh batt the performance is noticeably increased compared to the SLA. My personal opinion on your setup is that the batteries are probably capable of delivering the power necessary, but the weight is the thing.

Ashley

Edited By ashley needham on 06/05/2014 08:43:53
6 May 2014 at 08:47 #48729
CookieOld
Participant
@cookieold
Thanks Paul and Gareth no one mentioned the lack of current delivery to me before , I think i will go with NiMh

Thanks Again Dave
6 May 2014 at 08:48 #48730
Gareth Jones
Participant
@garethjones79649
Ashley,

Why would you need to change the motors to use Lipo Batteries?

Gareth,

PS by the way I loved your videos, some great ideas there, sorry for not replying before now.
6 May 2014 at 09:22 #48733
ashley needham
Participant
@ashleyneedham69188
Gareth. Just meant that if you were going to the expense and weight saving of Lipo`s then you may as well fit hotter motors. Sorry didnt make myself clear. Obviously there is a benefit of using Lipo`s without changing motors due to the weight saving but I was also running on the assumption that David may well have a Nimh charger for other things and so a more expensive Lipo changer would then have to be bought if going to Lipo.

Its all about the ideas. I shall run out eventually you know.

Ashley

Edited By ashley needham on 06/05/2014 09:23:02
6 May 2014 at 09:30 #48735
CookieOld
Participant
@cookieold
Thanks Ashley, The general opinion seems to be NiMh will be best , Just to change the subject slightly what thinkness ply would you lads say would be best for the bulk heads in a big Perkasa , I have a badly twisted hull

and have made a jig to pull it back to shape and am now ready to make the bulk heads and epoxy them in to hold the hull in shape once i remove it from the jig.

Thanks Dave
6 May 2014 at 18:45 #48743
Empire Parkstone
Participant
@empireparkstone
I run a 1/24 PT 596 3 nameless motors 2 x 8.4 3800 nimh in parallel gives about 15-20 mins continuous up on th plane longer if I drop her down now and again granted not as big as a 1/24 perkasa

Edited By Empire Parkstone on 06/05/2014 18:46:54
6 May 2014 at 19:00 #48744
Paul T
Participant
@pault84577
David

For the bulkheads I would use 5 layer 7mm ply with a few weight reduction holes, this thickness of ply will provide sufficient rigidity to maintain the hull shape.

Paul
6 May 2014 at 19:53 #48746
CookieOld
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@cookieold
Thanks Lads
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