New concept on Rigger design?

[Ub Hauled]

seriously, how does that wing on the sponsons help the hull... oh, I know!
It makes it go slower thus more stable!

w/o knowing what the owner had in mind is anyone's guess.

[raptor347]

I want to see a picture of the bottom of the sponsons and tub before I comment too much.

First impression, huge amounts of lift to carry the weight of a bunch of NiMHs. It's a big boat, those 9 series chameleons are about 10" wide. 18-24 cells? From the picture of it running it still doesn't have enough lift, judging from the water coming off the ride surfaces.

[egneg]

It is hard to tell from the pictures but the foils on the back of the sponsons look as if they were added to create more lift ... an after thought to compensate for the original design flaws.

[lonewolf]

There are plenty of pylon racers capable of 200 mph can a rigger??????????
maybe the approach(theory) has been approached from the wrong point of view.

When flat out running how much of a rigger is in the water???? There are ero guys that run an air rudder not a water... a flat out rigger might be skipping a dime size area on the fron sponsons and the prop in the rear....

Make a 200 mph plane skip the water surface... now make it look like a boat.

Can I desgin it prolly not but just a thought. Not trying to start a debate really just kinna thinking outside the box............/pond

[raptor347]

I've played with a bunch of ground effects projects, including some rolling surface wind tunnel work. Aero principals don't completely go out the window, but things don't work exactly as classic aero predictions indicate.

If you have a SAW rigger running really well, the sponsons don't touch the water at all at speed.

I think the power is there for a rigger to run 200mph. Not with the current designs, but the potential is there.

The real question that comes to mind is does this hobby really need 200mph riggers? If so, where do we run them? Legg isn't big enough. The fastest pass I've made is a tick over 117mph and I've flown plenty of 200mph pylon racers, but I don't think for a second that I'm ready to drive the 200mph rigger.

[Simon.O.]

Bugger me, this is a subject that was given a bit of work on rrr a while a go. I should know as I started some of it.
I will answer some of the questions that have come up in this thread, there are no attacks on the authors just my answers.
Do we need a 200mph rigger.?
Yes. To show that it can be done.
Will the current designs get us to 200mph
I can safely say no to that one as there has been very little change in speed for a few years now, not surprising as there has been no quantum shift in the design of hulls.
Flying a plane at that low level is difficult I am told.

I have done an imense amount of reading on WIGE craft, riggers, Blown drag boats and WWSR boats. I think we will all agree that models and full size have little in common.
I believe that riggers are fast and can be a bit faster but not 200mph.
We now have the power so where is the speed? It is lost by a hull that will not go faster.
I have experimented (well still do) with a Canard hull. I have come to the conclusion that for SAW the rigger is quicker.

Something is faster than a rigger and still has its prop on the water, what that hull is I don't know..........yet.

Bear in mind I am only at 40mph so am no speed expert on the water.
I do however read a lot and as you know I ask some wierd questions too.

[785boats]

What a great looking setup.
For what it's worth I think those winglets on the sponsons are either to disrupt the airflow over the back of the sponson that is creating lift or by the angle of them they are being used to create downforce trim.
Bear in mind that the top of the sponson is basically an aerofoil section that creates lift. The faster it goes the more lift it creates until at a critical speed it will lift off the water & possibly blow over.

But have a look at this.
Notice how the top of the sponson is flat & the underside is a shallow sort of D shape. No ride plates or sharp transoms to break off the water.
And yet it seems that they are only breathing on the water. No spray or wash.
Can anyone explain how these may work.

[Ub Hauled]

the sponsons are design to create a slim cushion of air and if all goes well,
you stay on that cushion of air until you let go of the throttle...
if you look closer at the picture you'll notice that it actually does have a
ride pad, regardless, it is very well setup... where did you get this picture?

[Fluid]

Having watched the fastest R/C boats in the world running well over 100 mph - FE, nitro and gas - the designer of that model has just copied and exaggerated the designs of others (the JAGs models in particular, that seems to be a cottage industry in Germany recently). No real problem with that, all riggers are just evolutions of older designs anyway. The fastest designs - that actually run fast - are generally simpler than this one. KISS works, especially with FE race boats. Extra parts left off don't break or get out of adjustment. And notice that this is not a SAW rigger, it has a turn fin.....

The comment that we can't get to 200 mph now because the current speeds have not changed in several years is - based on a lack of understanding of that aspect of the sport. No one has even tried to exceed the current 140+ record, that's why it hasn't changed. It has nothing to do with power or hull technology.

As Brian stated, "normal" areodynamics don't work with boats, the physics is much different. Boats operate in ground effect, a fact that only a few rigger designers seem to grasp. We can think all we want about what might work, but the reality is that mosts ideas have already been tried and found wanting. There are probably multiple ways to get to 200 mph in rigger design - we have the power right now - but do we need that? Can we find ponds large enough to get there safely? These are questions that have to be answered before someone seriously tries for 200 mph - and only a handful of people on the globe could do it even with unlimited budgets. I know of no one (who might have a chance of exceeding the 140 mph record) who is currently trying to break it, including the current record holder.




.

[Jeff Wohlt]

Jay, do you feel Joerg got lucky hitting the 140? Do you think he was hoping for faster?

How stable was that boat at 140 mph? Seemed very stable in videos but that is hard to see.

I heard Joerg was wanting around 150-160 mph.

Has anyone heard from the Germans lately?

Just wondering.

[785boats]

Ub Hauled.
Thanks for the explanation. I haven't built a rigger yet, but I intend to. I seem to have some motors, ESCs, hardware & drivelines lying around doing nothing. Seems like a good idea to build a rigger around them. A few other projects to finish first though.
The picture was posted on R/C Groups some time ago by someone in Taiwan.
We asked for more details at the time but it wasn't his boat & he couldn't find out anything about it.
All the best.
Paul.

[raptor347]

I agree with Jay. The record hasn't changed mostly because nobody is attempting it.

Quite honestly, I'm happy running my 80-120mph 2S and 4S boats. Besides, I have equipment for those classes. With the current economy, I'm not buying a bunch of new stuff.

[Ub Hauled]

Jeff, I was there and trying to pick JAGs brain... the record was broken with the same exact motor he broke the records in prior years, he was setting things up and told me that he was going to try a hotter motor once things were dialed... he was using a 2250/8 and was going to a 2250/6 expecting 150 maybe 160mph.
he was having all sorts of obstacles, two hulls sunk (one found), lost a rudder, etc... when he
ran his record breaking passes, as you can see on the video, he cartwheeled across the second light indicating that the he would have been faster if stayed in the water.
Now, as far as luck goes, at those speeds there is ALWAYS luck involved, there is only so much preparation one can do... for example, how does one prepare for fish or turtles that are taking a stroll near the surface? The answer is, shear luck.

BTW, I hear that the JAG team is revamping their hull design and will come back to play with us when they are done.

[Jeff Wohlt]

I have to wonder if there are issues when a person is WFO at 120 mph and then shuts down instantly. What happens with the prop stopping so fast. Like a fast break almost.

Or do they come off the throttle easy?

Brian...how do you come off 120 mph? Quickly let off or do you have to ease out of it? Just wondering about that.

[raptor347]

Jeff,
A lot depends on the braking characteristics of the motor you use. The slotless designs freewheel really well with the brake disabled on the ESC. The Toothed stator motors naturally have more braking effect and you have to be a bit more careful on decel. It has to be a controled deceleration, you can't just jump off the throttle.