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.]

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!!

[egneg]

So are you going back to 6 cell's and brushed motors?

[andym]

This probably a good time to mention marine ply! even 2mm would be a lot better than balsa.

[crabstick]

its PLYTIME!!!

IMO a boat should be able to survive a fast blowover... its fortunate the sponsons stayed attached and you didnt loose the tub to the depths.

[Simon.O.]

its PLYTIME!!!

IMO a boat should be able to survive a fast blowover... its fortunate the sponsons stayed attached and you didnt loose the tub to the depths.

I have rebuilt the sponsons only a little stronger than before.

Here are the reasons.
It has survived 40+mph flips before, the only time I ever damaged this hull was when I met a bouy coming the other way !
It is very stable at 40mph and as worst I will run 45mph setups.

I was trying out the 8S on 3S lipo as a one time event.

It was very eye opening. The prop was over 40k and I managed to bend the tips forward.

It will be my fun rigger and I will concentrate on pushing the bigger rigger for speed.

[crabstick]

did the GPS register altitude when you flipped?

[Simon.O.]

When a small rigger like this is running clear of 45mph is it good to see spray off the prop only ??

That is what I had this morning. The sponsons may not even be touching the water, there is no spray off them. There is a little wisp off the right but there is a turn fin there so it may be the fin causing all the disturbance.

There is one small problem with it running this way, anything more than a hint of left will roll it......fast
I can counter this by lengthening the booms or learning to drive better and turn right when ducks wander out onto the straight.

I am very happy with this hull now.
All it needs now is a 7S to replace the 8S, Hmmmm now who might have one of those ??

[Simon.O.]

I can counter this by lengthening the booms

I had a bit of time on my hands this afternoon so I did the widen job.
I cut the booms then cut a set of stainless rods as inserts and alloy tube as spacers.
The tube spacers are really only there to ensure the "widening" gap is the same all round.
I epoxied the ss rod inserts in and then sealed the lot with heatshrink tube.

This rigger needed to be widened and I can tell you know that for my next rigger I will not bugger about with cf or gf tube for booms. I will go with thin wall SS tube

I can forsee only one change in handling by making it wider, and that is it will not roll when I have to go left to avoid a feathered obstacle.

[Simon.O.]

One of the more insane things I have done.
3 cell to the 7S to a 432 prop.
The numbers stack up to 46krpm and mid 60's for speed.
I had a kind officer radar it for me on the second pass and got 101 kmh or 63mph.

Now it will return to the normal 2cell with either a 632 or a 1732 prop.

[Xzessperated]

One of the more insane things I have done.
3 cell to the 7S to a 432 prop.
The numbers stack up to 46krpm and mid 60's for speed.
I had a kind officer radar it for me on the second pass and got 101 kmh or 63mph.

Now it will return to the normal 2cell with either a 632 or a 1732 prop.

Well done Simon. That is fasttttttttttttt in anyone's books. There has been some fast speed recorded with small boats and lipos lately. Fast and not so expensive is a good way to go in these troubled times. Keep slicing that Balsa mate.

[Simon.O.]

Well this has been a fun hull and is now showing a bit of age. The sponsons have been stolen to go to the Canard as a result of me driving it into a Bouy and the damage that occurred. See my Canard thread.

The new sponsons for this one are a lot stronger and a bit narrower than the last ones.
You can see the internal framework in one of the pics. The inner skin is 3mm and the outer is 5mm, there are solid ply block for me to drill into to fit boom receiver tubes.

I'll see how these sponsons go and if they perform then I just might make a new tub too. There are a lot of things I have learned from this rigger and I am confident I can make a better tub with a more user friendly layout.

For now we have new sponsons on the build.

[Simon.O.]

Progress is slow as I have a lot of other stuff on the go.

It is nearly ready for assembly and here is what we have today. Just waiting for some varnish to harden and then I can get on with some epoxy bonding.

The sponsons will sit with 5+ deg AoA which is a little more than the old spoons. I will test these with a few setups from high 30mph through to mid 60mph and see how they fly. The old ones were a very different shape but these are similar to my saw spoons for my big rigger.

I have already drawn the profile for a new tub.

Enjoy !!

[Meniscus]

You know, that motor looks familiar! Looks good Simon.

[Simon.O.]

You know, that motor looks familiar! Looks good Simon.

Close Ben, but no cigar. That is one of my old 4400kv 8S cans, your old 7S is in my Canard.
I will give this 4400kv motor a dose of 3S for giggles
It should be on the water at the weekend for trials, I have a few setups I will test to see how these new sponsons go.

[Simon.O.]

I had this baby out on the water today with the new sponsons and all was ok, not great but ok.
A small drilling error in the new sponsons put my AoA at near 6 deg which is way too much but I figured I should try it anyway.
The wind and chop was up and the rigger was all over the place, it tracked straight but was real bouncy on the front as the AoA of the sponsons was too much as we know.
With no real way to adjust the AoA I have no option but to build a new tub

This will become a new Build-thread.

[Meniscus]

6 degrees may work, you'd be surprised sometimes. I'm trying to recall what AOA my Matrix has, but it's over at Danny's at the moment. Perhaps he could measure for you.