28" H&M rigger help

[olwarbirds]

I just got this 28" rigger http://forums.offshoreelectrics.com/...099#post604099 This is my first rigger and I'm not sure what kind of power I should be putting in it or what prop. A 4S lipo just fits but it seems big for this hull. A 1515 fits but its really tight. I want to set it up for "Saw" or drag racing. What should I be looking at ? tks... DJ

[srislash]

I had a 2000kv LMT 1940 in my rigger when I got it DJ. I am going to go with a 1415 2400kv now. I think mine is about 30". Guess I am trying to say that a 36mm can should suffice. Something with a little higher Kv and you should still only need a 120 amp speedy, for sport anyway.

[Scott T]

This thread has some info - http://forums.offshoreelectrics.com/...ighlight=xzess

I bought one recently myself and plan on putting an old 8XL in it on 4S for fast sport running.

[Scott T]

Mine is actually the one in the thread with the clear plastic front spoilers. Andy had cut the rear boom and stiffened the area so there is a lot more room for cells.

[egneg]

I did the same to mine at Andy's recommendation. I had a modded F 8XL as well on a wire drive and a M545. Very hard to keep on the water over 60 mph. Paddy removed the foils and had much better results.

[olwarbirds]

Here is what I'm thinking, pls tell me if I've lost it Neu 1415 or 1509 or something similar, 4000kv, 3S lipo, I have a H7 prop done by Andy Brown...if anything it should be fast.

[srislash]

Here is what I'm thinking, pls tell me if I've lost it Neu 1415 or 1509 or something similar, 4000kv, 3S lipo, I have a H7 prop done by Andy Brown...if anything it should be fast.

That should work DJ. How many mm's is the prop?

I have only had mine out a couple of times and was only running a 40mm prop.

[Scott T]

I think 4000kv is a bit high on 3S, something around 3000 - 3200 would be better.

[larryrose11]

I have found that in general, it is better to have a lower KV, and higher voltage. 4000 Kv on 3s is the same as a 2000 Kv on 6S on paper. Under load, the lower Kv / higher voltage combo will spin the same prop much faster. This is because of the higher KV motor will dray way more current, and the battery voltage will sag much more, lowering the motor RPM.
IN a rigger, it is all about the motor RPM, but you need enough torwue to get it up on plane.
Why not have a Castle Creation 1515, 2200KV motor on 4-6S? They are common, and robust, and rated for 6S. A small M6 prop will go like poop.

[olwarbirds]

Shawn after checking that props size its too big...I will save it for my next larger rigger..
Scott, yes I am going a bit lower on the KV..
Larry, correct if I had room for a lipo with enough mah..wish I could go 6S

I got a Hacker B50 7L 3450kv this should boogie on 3S with a modded 642 prop and give me room for my T120

[srislash]

Shawn after checking that props size its too big...I will save it for my next larger rigger..
Scott, yes I am going a bit lower on the KV..
Larry, correct if I had room for a lipo with enough mah..wish I could go 6S

I got a Hacker B50 7L 3450kv this should boogie on 3S with a modded 642 prop and give me room for my T120

Haha, I have a B50 6L 2630kv here

[NativePaul]

That hull used to be very popular here for racing in the hydro 2 class on 12s NiMh and then 4s LiPo, I still see the odd one racing although the Dr Super Evil has replaced it for most people, most high C 4s packs should fit and the ETTI/VB/Aspec 6s 4500/Desire5000 6s packs will also fit which is what most folks race with now, but are a low C pack so it may be better to stick to high C 4s packs for SAW.

They were designed for 12s sub C NiMh and with the higher speeds and lower weight of LiPo they had a bit too much lift, most of them here ended up keeping the wings, but widening the track with carbon booms about half an inch out side of the wings, which spilled just enough tunnel lift to restabilise them at the new higher speed and the wider track allowed for faster cornering. Hydro2 is oval racing on about 1KW, with speeds in the mid 50s, for SAWs I suspect you will want to cut down the wings or remove them altogether.

Reinforce it, H&M riggers are built fairly light to go fast on limited power, and the 4s rigger record is over double the boat's design speed.

[olwarbirds]

Tks Paul, I had done some research on it. But so far had not found much. I will tear it down and do a CF inlay. Its already got cf booms in the wings so it will be easy to widen the stance some. I bought this hull to learn about setting up a rigger, I am going to be getting a larger rigger from BBY soon...tks for all the info... DJ

[olwarbirds]

I've got it about all together, was wondering about CG on a rigger. Is it similar to a regular hydro ?

[srislash]

Usually a little farther back DJ, not a lot but a bit. Not sure of exact %, hopefully someone else chimes in.