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Old Sep 01, 2013, 04:45 PM
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Very nice work. Would love to see how these boats would 'fly' with an airscrew instead of a surface piercing prop
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Old Sep 08, 2013, 02:51 PM
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Hi Lohring,
that´s the right way ,have a look at the wig planes. You see that all the boats you show have the same problem .The design the sponson to much in front and ad lift that will rise with the speedrise .No Airplane designer will ever do such silly thing. Look at the Ecranoplane ! The sponson is placed at the wing and will only help to stabilise during start and never touch the water surface at full speed so no drag ad . Build a Ecranoplane and drive it with a surface pricing prop and you will set records in all boat class . Notic as you want to be a boat you need very less wing aera for the lift at this speed but the stabilizer wing has to be big and high above the water and all other wings .And it has not to produce any lift .
All the record holding boats you show and also the record boat from the JAG´s team are on the end of speed of this design as the body produce enough lift to fly the boat but there is no stabilization sytem .A possible way is also a lifting body design in ground effect ,you find such design by the NASA X-planes history .There you will see also big flap that correct the flylevel when the lifting body comes to toutch down befor landing on skis. Most use a delta body design with 72 deg. swap back angle.
Do you know the pics of the Russia Wigg boats with waterpropeller ?
Some design use the surface propeller in the front ,pulling the boat ,we succesfully do with a duration racing canardboat 2 kg Naviga class.
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Old Sep 12, 2013, 04:46 PM
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Christian

It's good to hear from you. I think you are missing a very important point with the boat designs. There are actually two wing systems. The main wing is the body of the boat. The secondary wings are the sponsons placed well forward. The sponsons are in very close ground effect and their lift changes much more quickly with height than the main wing. In high speed movies of Joerg's boat and others, the sponsons seldom touch the water. On Mike's sponsons, air traps enhance this effect. The result is both lateral and longitudinal stability with low drag. Of course when the main wing gets seriously out of shape, the boat blows over. It is a careful balancing act. The setup is like a canard airplane, but the sponsons have a very strong variation of lift with height and therefore strongly maintain the main wing angle. Mike's model boats have been exceptionally stable once they were properly set up.

I don't think anyone uses a big enough rear wing for stability in boats. It needs to be well over 1/2 the area of the main wing. We've been fairly successful without one, but we run in straight line over a narrow speed range and in close ground effect. Full size vehicles need to be able to fly over obstacles, a much tougher problem.

I'm working on a model "catamaran" that planes on the forward rather than the transom end of the sponsons. The basic layout will be similar to Mike's designs with full length air traps. I might use twin wings after reading all the experiments posted here. We'll see how it works.

Surface piercing propellers add their own flavor to the WIG problem. They force the vehicle to run very close to the water's surface, but provide a lift force. Traditionally the propeller has been at the back, so that's where the lift goes. This balances the wing's more forward lift for a while. The propellers lift varies as the square of the rpm; vehicle speed varies directly as the rpm; and the wing's lift varies as the square of the vehicle speed. That means both lift forces vary in a similar way. It's very helpful and can be adjusted to match over a limited power and speed range. However, the propeller will run with very little depth variation compared to the possible wing height variation.

A water propeller is less efficient and adds a lot of drag. I bet all the boats would run faster with air propellers and rudders, but the rules don't allow it.

Lohring Miller
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Old Sep 13, 2013, 02:37 AM
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Ekranoplans on TV

Hi All,

Just a note to say watch out for Discovery Science "World's Strangest
Machines" TV show currently being broadcasted which features a small section
on WIG.
Some of the usual footage, yes, but also some shots of the WSH500 in its
shed just before the recent sea trials.
Oh, and some old guy pretending to be an expert....

There are several other interesting technologies on the show too.


Cheers

Graham
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Old Sep 13, 2013, 06:02 AM
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Thanks Graham. I seem to be stuck in a rut, not much to show thes past couple months.
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Old Sep 13, 2013, 04:28 PM
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Hello Lohring,
i agree with you how the sponson and the wing worke like a canard design .BUT this are two different aerodynamc actions ,as te sponson work only by copressed air and te wing section work with compressed air and aerodynamic flow over the top surface. Jörgs rigger need very carfully adjustment and at last angle of attace of te sponson comes to sero .As you can see by tethered line rigger they never ave sero angle of atace .They counter act to much lift by ading downforce producing wings or grind flat surface on sponson top . But all have problems with this sponson lift as it dosn´t produce lift at cg. OK canard design will also not produce lift at cg .some lift behind and some befor cg but if a wing canard will rise nose the front wing loss lift befor the rear wing loss it lift and the plane comes down to level flight .Sponson loss nolift the rise lift as the start airborne .In my eays a very bad aerodynamic system.
I post a pic of my Octura wing Ding 20 running down straight 30 years ago.
with a big wing at the back at intlwaters fred reward sponson riggerdesign.
Currently we are testing our new propeller design i think i show you .
The boat run first with a propshop 6514/2 prop ,taking 240 amps peak and 150 amps on the straight doing a top speed of 155 km/h.
With the new prop design 6518/2 it took 180 amps peak and 80 amps on te straight reaching speed of 166,2 km/h and still acclerating doing a blow off.It´s a offshore tunnel hull on 10S 5000 mAh lipo bat.This is much moore than we hoppe to get.
This weekend we have in Germany our world record event for high speed modelairplane and helicopter .We have a team of fife pilot with planes and 2 with helicopter.All with outrunner motors.first test fly of the Banshee helicopter show 292 km/h .That´s 50 km/ over the current record held by them selve. The planes hope to do 480 km/h ,but at this speed it is very difficult to fly between the marks corridor 35m max high over 200 m distance . Have a look at the high performance forum here in rc-groups next days.
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Old Sep 14, 2013, 11:31 AM
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Christian

Sorry my propeller project along with some other projects got put on hold for a while. Good luck with your efforts. It's very hard to get a model boat over 140 mph (225 kph). Water is hard and unforgiving at that speed.

Usually the fastest model boats try to reduce or eliminate lift because they have a lot of power for their size. Outrigger hydroplanes are the result. Mike and I did months of testing on his outrigger. His original idea was a flat bottom airfoil shaped center section with a smooth top to eliminate drag. He, and most others, don't realize that water is 800 times denser than air so the same object in water has 800 times the drag. Air DRAG is insignificant compared to the drag of anything that touches the water.

I think aerodynamic effects (lift) are more important for stability. We tried a huge number of different changes in sponson and center body design. Below is my summary of our findings:

1. Increasing the center body lift with air traps unloaded the prop so it "blew out". Changing the width of the center body didn't make any difference.

2. Airfoil fairings on the sponson tubes didn't change the speed at all, but could be angled to provide down force if needed. They reduce the drag on a round tube by a large factor. Smoother sponson tops looked pretty but didn't add any speed either.

3. Air traps on the sponsons were good for 2 mph at 103 mph.

4. Changing from a thick aluminum wedge rudder to a thin, tool steel wedge rudder increased speed 6 mph at 100 mph. This was the biggest single improvement. Shortening this rudder 1/8" (3 mm) added 2 mph at 108 mph. That 109+ mph two way record for gasoline fueled boats set in 2004 still stands.

5. With the existing propellers, rpm with some power was everything. The difference between a Quickdraw's and a Zenoah's speed in the same design boat was the difference between 19,000 rpm and 23,000 rpm at top speed. Later propellers with higher pitch allowed the same boat with the same Zenoah to increase speed from 98 mph to 107 mph. Electric motors don't have this limited rpm problem.

6. Killing the lift on our sport hydro's wing with big spoilers allowed it to run over 100 mph without blowing off. Without the spoilers it blew off at 75 mph.

I still hope that I can find a combination of a WIG style boat that will be faster than non lifting designs. Mike's later designs ran well, but were not faster than the original rigger. I've not had much success so far with my new attempts.

Lohring Miller
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Old Sep 14, 2013, 01:49 PM
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Hello Lohring,
jet back home from todays records. Lots of records set today by our team Powercroco.
Doing 290 mph with the electric powered plane , 168 mph electric helicopter , 260 mph combination electric Batterie system , 2 houre and 31 minutes duration fly electric helicopter , and at last a new Guines book of records Jet powered modelairplane doing crazy 438,8 mph . That's today but tomorow the can set some moore.
With the boats i want also to go moore wiggplane with less lift only produced by the sponson set at the position of the wing. Driveline with two couterrotating propellers to need a very small ruder or no ruder. This year i have test a small rigger without ruder only with the counterpropeller from a modelhelicopter that can fast response some torque action from the propellers . As the centerbody of the rigger is very narow it will give a good straight line during accleration untill speed is fast enough that the tail aerofin will holdnthe straight . But need counterrotating propellers. But also this twin propellers give very fast accleration times . So you need not to drive the boat to far away. At my age it is very usfull if the boat is not to far away .I see it today with the airplanes ,sometimes i lost them in the blue of the air as they become so small when they climbe high in the sky at this speed.
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Old Sep 14, 2013, 05:33 PM
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I've got a few spare sheets of corflute left over from another project, and I was thinking of using them to make an Ekranoplan. I was looking at the lippisch type, and came up with the following plan to make it;
Cut out an iscosolese triangle of corflute, with the flutes running at a right angle to the long edge.
Cut down the centeral flute, fold it with the uncutside outwards as far as it'll go, and stick with a strip of duct tape down the middle.
Cut & mount a stabilising fin, with a rudder.
Mount a ducted fan, servo, and other ancilliaries where they'll fit.
See if it works

Does this design stand a chance? And is a lippisch stable enough for 2ch control, or would I be better off with a bixel? (I've only got 27mhz 2ch gear at the moment)
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Old Sep 16, 2013, 01:12 AM
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You can always combine your 2chan rx with a gyro+acc 3axis stabilization system. I will do the same thing.
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Old Sep 17, 2013, 10:16 AM
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Congratulations, Christian. Keep us informed about your boat projects. I would think a counter rotating prop would help with some issues, but does it have more drag? The only way is to try and see. I would think that the most efficient setup would be two motors, one with a hollow shaft that allows the rear motor to drive one of the propellers. That should have less drag than any geared setup. Post some pictures.

An air rudder should have less drag at speed than a water rudder, but it needs to be big. Twin rudders give enough area without looking oversize. Laterial stability is as important as longitudinal stability. I've seen lots of straight line riggers sponson walk to destruction. I think the air trapped sponsons help, but I'm not sure.

Lohring Miller
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Old Sep 17, 2013, 09:32 PM
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I experiment with planes that fly near water as well as take off and land on water

You guys notice if cg further back its way better
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Old Sep 21, 2013, 11:07 AM
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It depends on the configuration. I'm experimenting with an outboard tunnel hull. They traditionally have a rearward CG and fly well with a CG at around 30% of the length from the transom. The sponson planing lift balances the forward lift of the wing. However, the boat has to "set", get the forward edges of the sponsons in the water, to turn. Too much wing area too far forward prevents this.

Our outboard hydro also has an aft CG. At around 80 mph it lifts the transom out of the water and fully flies with the sponsons and transom occasionally touching. It starts to get unstable, though, when running like this.

Lohring Miller
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Old Sep 23, 2013, 08:30 AM
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Hello Lohring,
yea this things are only driveable if a human sensing system is on bord. Poposensing . Here we call this a flying ironing bord .Most on the first lap when the water is like a mirror you can fly down the straight ,during racing they most touch the water wave to wave.This are all very dangerous flying systems ,to many lost life with this boats. But every close to watersurface vehicle will be near unknowen surprise . Thats wy we see not very much Wig plane/boats around.
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Old Oct 07, 2013, 10:43 PM
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IMHO if we want to fly we need to balance to fly, CG ahead of lift center. Either add wing area aft, like bixel type outboard horizontal stabilizers, or move CG forward, like driver, engine or both. don't forget a vertical tail!
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