Outrigger design reward sponson to cg.

[hugh hargett]

Hope this thread continues. Alot of really neat stuff being posted here.

 

[lohring]

It's easy to test radical ideas with models. I love the twin wing mono. The twin wing should be stable longitudinally and has had some success in full size WIG craft. The difference between Mike's outboard hydro and your canards is the wide sponson stance. This adds a lot of lateral stability to prevent the crash the video shows. Wing area turned out to be critical. The wing was shortened after the first run, an easy field modification. We tried shortening the skeg after we set the record, but the boat lost directional stability. I'm considering a P spec tunnel that will look a lot like the twin wing mono with a smaller center and two full length stepped sponsons. It will actually run like the outboard hydro but look like a standard tunnel. I'm also considering a three axis gyro system for stability augmentation using flaps on the wings.

Lohring Miller

 

[John Finch]

It's easy to test radical ideas with models. I love the twin wing mono. The twin wing should be stable longitudinally and has had some success in full size WIG craft. The difference between Mike's outboard hydro and your canards is the wide sponson stance. This adds a lot of lateral stability to prevent the crash the video shows. Wing area turned out to be critical. The wing was shortened after the first run, an easy field modification. We tried shortening the skeg after we set the record, but the boat lost directional stability. I'm considering a P spec tunnel that will look a lot like the twin wing mono with a smaller center and two full length stepped sponsons. It will actually run like the outboard hydro but look like a standard tunnel. I'm also considering a three axis gyro system for stability augmentation using flaps on the wings.

Lohring Miller

Let me know if that works for you Lohring. I was on the fence with trying that and went to a wing on third servo. The wing could be adjusted while running and it worked on my gas sport hydro to adjust the ride. It was located between the front sponsons and only one inch in size from front to back. I could adjust from full push down in the front at 20 degrees to actually lift the back out of the water to a 20 degree lift to blow the boat off the water. Problem was as had originally suspected, that if the boat crossed a ripple fully aired out, the wing would change angle of attack and carry the bow off the water. I don't know if a gyro could work fast enough to change the angle of attack to prevent blow off. Anyway, I decided it was a project that would take a lot more time than I had and decided to go with the old methods of tuning a hull.

 

[Christian Lucas]

Hi Lohring , John ,

this wing will work and a gyro stabilisation will also do the job for the most influence .if the boat start to lift of by aerodynamic this ocures not very fast and the electronik has enough time do correct the flying position. Only if a hard kick from cross running waves hit the sponson the electronic has no luck to counter this impack.But for such kick we have to use shock absorber on the skidplate .

Do know the reverse front wing design from Fabio Buzzi record petrol hydroplane ? (pic 1 and 2) i used this design at my balsawood scrach build tunnel . My most loved try and error testboat is a SK Daddle from Dumas with various drives .Z-drive and Levi tunnelruder and Arnesondrive and many different trim tabs ,short and super long outrigged . Also with K&B 3,5 lower unit outbord.

John for you the hydroplane i saw years ago in Sweden with back set wingsection .

Today i want to go on building the rigger ,but here in Munich start on Saturday the Oktoberfest and i meet some friend having fun there.

 

[John Finch]

Thanks for sharing Christian. Have a great time at the Oktoberfest!

 

[wayne middlemiss]

hi guys i have been keeping an eye on this thread with interest, this video on youtube CAN HYDROPLANES FLY will be of great interest to all doing kilo runs flying . the boat looks to be ed karelson design.

the pic of the white hydro with the picco in it there is a 21 size version of that exact same design in my local area an interesting boat . sorry i cant post a link for you tube but somebody may do it.

 

[lohring]

Can Hydroplanes Fly is exactly the problem. A single wing in ground effect is unstable. At model sizes we don't ever run in conditions that smooth. A rear wing adds stability while a moveable front canard adds control. Even so, unlimited hydroplanes still blow over. I would thing that electronic stability augmentation would help. We tested a big fixed rear wing on the scale model for an electric hydro. The most interesting result was that really huge deflections didn't make much difference in either speed or ride attitude.

Lohring Miller

 

[wayne middlemiss]

as most of us do understand setup with good balance is all you could realy do ,as for wig craft and using that idea for boat desgns its doesnt constitute a boat as we now know them as.

as its said flying planes above the wige is easy but within it is unpredictable.

 

[Christian Lucas]

Hi Lohring , Wayne ,

i think we have to go moore wige . spezial the Ekranoplane show how it will work without lot of electronic.

Lohring for my understanding your tail unit (tail wing) is to small .It need a big hand to control the wing in groundeffect. But the main problem are the sponson in my item centered view ( that the translation i found ) .I made 3 easy drawing . #1 show wing and tail unit without sponson .like a wige it will work most time. #2 show the wing and tail unit with sponson .Here you see that the sponson ad lift outside the c.g. and at the bow that will blow of the boat. Have also in mind what happen if a wave hit the sponson at this point .The kick is hard lifting the sponson and lope the boat . # 3 show what i want to do ,going moore the way of wige craft but i want also not use a wing . I want only the right positioned sponson and the lift that is produced by them ,no wing or centerbody has to ad lift . For that aslo the centerbody will get a verry narrow design . And at the tail i want a big control tail unit .

 

[John Finch]

I tried a rear wing on a rigger with third channel controlling the adjustable elevator like on an airplane. The results were no effect at all. Perhaps the wing was too small or perhaps disturbed air from the hull nulified the effect. It appeared to be the prop lift was the strong determining factor on the ride at the tail of the boat rather than the wing.

I experimented with the rear wing as described by Christion as well thinking since the wing was behind the prop that if the front of the boat lifted it would pivot on the prop and push the wing to a positive angle thus pushing the bow back down, but instad of pivoting and pushing the bow down the wing just lifted the whole boat out of the water and it turned into an airplane.

Also experimented with a twin canard thinking the rear wide body would keep the boat from flying but found it to be wrong as well. It seems the only way to keep the hull on the water is to fly the hull at a neutral to negative angle of attack. If you run a positive angle of attack the boat will finally reach a speed where it blows off. A balance act between lift and weight and speed. I have found rudders above the hull to add stability on some hulls for roll stability.

John

 

[John Finch]

Can Hydroplanes Fly is exactly the problem. A single wing in ground effect is unstable. At model sizes we don't ever run in conditions that smooth. A rear wing adds stability while a moveable front canard adds control. Even so, unlimited hydroplanes still blow over. I would thing that electronic stability augmentation would help. We tested a big fixed rear wing on the scale model for an electric hydro. The most interesting result was that really huge deflections didn't make much difference in either speed or ride attitude.

Lohring Miller

Now that is flying! What a video! Zero wetted drag on those sponsons. I like your SAW hull. Where can i get a set of sponsons like those?

 

[wayne middlemiss]

here you go some good reading for you all

26 - Migeotte.pdf

 

[lohring]

Without all the math, the issue with catamarans is that the center of planing lift is at the transom so as the wing lifts this component decreases. That lets the wing increase its angle of attack as the height increases, worsening the problem, especially since the center of lift moves forward as the height in ground effect increases. A hydro (sport hydro in models) with its forward sponsons is a better answer. If the center of lift is well behind the sponsons, increasing lift puts more pressure on the sponsons and increasing height causes the wing's angle of attack to decrease. However, that also increases the water drag, so there's a tendency to balance everything so the sponsons lift out like in the video. Then when the wing lifts out the center of lift moves forward destroying the balance. Added to this is vortex lift from the bows of the sponsons, since they start to act like delta wings at high angles of attack. Even a big horizontal tail isn't enough to stop all this once it gets out of control. Look at how huge the tails are on the Russian WIG vehicles.

John, the sponsons in the picture as well as all the rest of the boat were custom built by Mike Bontoft for our own use. It's all a hobby, and producing things for sale tends to ruin the fun. I still get calls about Leecraft tunnels, a business I sold to Alfred Lanza years ago.

Lohring Miller

 

[John Finch]

Without all the math, the issue with catamarans is that the center of planing lift is at the transom so as the wing lifts this component decreases. That lets the wing increase its angle of attack as the height increases, worsening the problem, especially since the center of lift moves forward as the height in ground effect increases. A hydro (sport hydro in models) with its forward sponsons is a better answer. If the center of lift is well behind the sponsons, increasing lift puts more pressure on the sponsons and increasing height causes the wing's angle of attack to decrease. However, that also increases the water drag, so there's a tendency to balance everything so the sponsons lift out like in the video. Then when the wing lifts out the center of lift moves forward destroying the balance. Added to this is vortex lift from the bows of the sponsons, since they start to act like delta wings at high angles of attack. Even a big horizontal tail isn't enough to stop all this once it gets out of control. Look at how huge the tails are on the Russian WIG vehicles.

John, the sponsons in the picture as well as all the rest of the boat were custom built by Mike Bontoft for our own use. It's all a hobby, and producing things for sale tends to ruin the fun. I still get calls about Leecraft tunnels, a business I sold to Alfred Lanza years ago.

Lohring Miller

I understand completely Lohring.

 

[John Finch]

here you go some good reading for you all

Thanks for sharing, but it lost me on page two of ten.

John

 

[hugh hargett]

That hydro was really on the edge. If you could hold it there you could get some major speed. I have to believe some active canard configuration would help. Without the wind tunnel and some math it will be hard to determine the proper amount of surface area to make a difference. You fellas got any aerodynamic formulas that can help? If so Pm them to me .The funny thing about alot of rigger designs is the tub is a wing anyway because of its profile. There are only a few riggers designers ive seen that have realized this and made some changes to deal with it.

Hugh

 

[John Finch]

That hydro was really on the edge. If you could hold it there you could get some major speed. I have to believe some active canard configuration would help. Without the wind tunnel and some math it will be hard to determine the proper amount of surface area to make a difference. You fellas got any aerodynamic formulas that can help? If so Pm them to me .The funny thing about alot of rigger designs is the tub is a wing anyway because of its profile. There are only a few riggers designers ive seen that have realized this and made some changes to deal with it.

Hugh

Read what Wayne posted. More figures than I can understand.

 

[Christian Lucas]

John ,

i am with you ,better go out and test at the lake than doing all that math.

Lohring,

this pic of the ekranoplane .When i see this ,the pilot cruising at 320 mph ,possible having all family on bord ,does he think what speed has Ken Warby driven in Miss Australia doing his boatrecord .

 

[Charles Perdue]

Many years ago there was a flying boat on the cover of either Popular Mechanics or Popular Science magazine. I believe that it was designed and built in Germany.

It was a reverse delta shape with an inverted vee bottom with small sponsons on the wing tips. The original had an airplane motor and prop in a pod on top of the fuselage but I used a boat driveline and propeller. I built a model of it, it flew surprisingly good. The reverse delta shape and inverted bottom of the wing was self-leveling without any extra controls needed.

I built a rigger with an inverted vee bottom and skirts on each side of the hull. The ground effects from this worked quite well.

Charles

 

[John Finch]

Charles,

I love the the statement born with nothing and still have most of it.

John