Simon's Balsa Rigger

[ED66677]

Hi Simon!
I just got back from vacation!
any vids someday?

[Simon.O.]

Still no moving pictures.
I am rapidly coming to terms with this BL motor game.
It has an 8S running 6 IB4200 cels via a 100A X-power speedy.
I still have my beloved plastic octura 431, 521, and 534.
So far the 531 is an absolute hoot, I have yet to run the 534 as I am still learning to drive this thing.

[Ub Hauled]

It is a lot of fun,
Riggers are on rails!

[Simon.O.]

It has been a while since I have written an update on this hull so here it is.
Since I have installed the BL motor the performance has been wild.
Given that this and the other balsa hulls were originally designed around a brushed 23t car motor it is no surprise that the handling has changed due to a massive power increase.

I am currently running 540 8S with a 531 plastic Octura prop I am waiting for a few more 431’s

With the rigger I have not had a blow over yet but have gone from a very wet sponson through to a wild sponson pad to sponson pad dance with an associated very loose tail.

I am leaning towards adding a ride surface to the bottom skin of the sponsons which will be approx 1”wide and ¼”deep 25 mm x 6 mm. This should now reduce the sponson wet surface and thus help to reduce the hydrodynamic lift that is there and in turn tame the little bugger down a bit.

Spectacular to watch as it may be, I am not getting full speed out of these hulls with the power that I have available.
The OB tunnel is another story. Blow overs are a blast as 9 out of 10 will land on its feet and drive away.

[Simon.O.]

At last I managed to get down to the pond and test the new sponsons.
It was a blast !!
I narrowed the existing sponsons by 10mm or 3/8’ so they are now 40mm or 1.6” wide at the ride surface.
I set the hull to run the tub parallel to the water and the AoA on the sponsons is approx 4deg, the front was very smooth on the water with no visible spray off the sponsons, there was the normal spray off the turn fin during a turn.

The tail sat a little low for my liking but I am sure that I can sort this with a few tweaks of the strut. I will leave the AoA at 4 deg for now and may consider a little more later to see if the front will loosen up any more.
One of the most interesting changes was that the tail is a lot more settled now, before i had some serious wobble in the rear and was looking at lengthening the tub to address this problem. not needed now.

It is now proof that the sponsons were indeed too wide for the power that I have in there. This is no big surprise as the boat was designed for a 19-23t car can on nimh cells.
I still have the IB4200’s in there but am now seriously looking at lipo.

The long and fun path to designing and building a fast rigger !!

The Hydro is next in line for surgury

[Simon.O.]

More runs this morning confirmed my belief that I need to invest in a few proper props.
I run the plastic Octura 431 531 534 at the moment and one Pro-boat carbon 434

No surprise that the 31mm dia wheels spin a lot more and don't load the motor as much.
531 is my best so far and the motor esc and pack do not get hot
34mm dia props start to heat things up up real fast.

I now need to read up on higher pitch metal props and get me a couple.

Curent setup is

Fiegao 8S , no-name 80A esc watercooled, 6xIB4200 or 6xIB3600.

Anyone care to reccomend a start point for a prop ????

[mobychev]

Simon, why dont you come down to Wattle park on this weekend (Sat preferably as we have a regatta on the Sun) I have a good variety of props you can try.
give me a ring on (09)2391177 and i will meet you there, I need to do a bit of testing too.
Graham

[Simon.O.]

Graham, thanks for the invite but I am off to Whangarei for the long weekend.
I still need to get down to Wattle pond some time.
My reading tells me that a 632 or X632 is a good start point.

I am waiting for Kim (Hpm) to get back to me on those.
I'll keep your number and PM you soon enough.

[Simon.O.]

While i wait for my boat money to grow for a set of Lipo's etc I thought I would give this rigger a whirl with some more power.
Last week one of my IB4200 packs dropped a cell.
A quick run with the iron and I now have a 7 cell pack that can go to 8 if I really want to, I think 8 is max weight for my CoB and will give me a loaded rpm of 34k which is getting up there.

With 7 cells on a 431 plastic it screamed.
On a 434 Carbon the tail was planted a little better and off it went.

The OSE calc and indeed my own calculations give me approx 70 km/h.
By eye it was there too.
If so then I now have a 40mph boat and that is a massive milestone for me.

I now want to get the Canard sorted and look at another hull to design and build over the winter.

[Simon.O.]

For a while now I have run this with a Fiegao 8S and 2S-5000mAh lipo on a x632 prop and all has been fine.

Today I tried a Fiegao 12S motor on 3S-4000mAh lipo with the x632 and things changed.

%&^%$$#@ It moves now !!

The maths for the 8S on 2S is very similar to a 12S on 3S, water time tells a different picture.

When I get to go down to Hakanoa to time the 4S rigger I will take this too for timing.
I am well confident that it blows 40mph, maybe more.

I am now very happy as I have two Riggers I designed and built that rock. !!
There ya go Scott, the banana guy again.

[Ub Hauled]

where is the video!
:D

[Simon.O.]

I am well confident that it blows 40mph, maybe more.

I was right. I tried my new gps today (thank you Paddy) and got 68km/h or 41+Mph

Very happy
and now having a beer. 1.30 in the afternoon.

[Simon.O.]

This was fun !!

Latest developments.
Over the last few days I have tried a 540-12S (2598 kv) on a 3S lipo with a 632 prop. I got 68 km or 42mph. Good so far
I ran a 8S on 2S to the same prop and got 70 km or 43mph. Very good

Today I tried something a little different.
540-8S on 3S !!
The possible numbers are.
41,000 rpm at the prop
106 Amps
1072 Watts
59mph ( 94 kmh)
I got 91 kmh (56 mph)

It was wicked fast and on the 6th pass it blew off. The pics only just show the damage.
The prop, 432, had the tips bent forward.
The tub was split at the rear so now has a whole new skin section where the servo is. The nose which had been damaged once before, split agian, the front section of hatch is still floating on the pond the rear section is fine.

A 5 minute tow in and all is good. The electrics were wet but all have survived and will go again.
The sponsons were damaged but the main sections of each were fine and I now have made the ride area a bit narrower. 35mm or 1-5/16”

Here are the pics as it came home and now in kitset form ready to rebuild.
Remember this is about a Predator size rigger.

[ozzie-crawl]

awsome speed but thats a bummer
iam sure you will rebuild it better and probably faster than before
who ever first said speeds addictive was dam rite

[andym]

Oh my Oh my Oh my, Simon I think that the building and repair work is 1/2 the fun. So it looks like you have a bit of fun ahead of you!!