Active tunnel wing for cat

[RandyatBBY]

From my understanding of the use on the full size boats, they create lift in the rear to keep the front planted and land smoother off big jumps.

@ Gerwin - I wonder if anyone has done one with an AVCS Gyro i.e. GY401 and a Fast digital servo. Theres Gyros and then theres Gyros..

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The full size boat has a lot more weight and Power to make the flap work. In a model the flap will create a lot of lift because of the packing of the air in the tunnel. This air will build and move forward the longer you run in a straight line, until it blows over the front of the tunnel, causing lift in the front of the boat. To keep the lift in the back the shorter the tab the better and possibly opening up the vent in the step in the rear of the boat.

[bonewar]

being a helicopter nut first, there are some very fast gyros and servos, I was going to do this on my 1/6 scale unlimited to control the lift of the wing.

its a great idea! but only testing will tell...(these servos are for fitment only)

Cat-Boi ,

What gyro/servo (very fast) would you suggest ? Thanks Bonewar

[bonewar]

OK i bought a futaba GY401 and a futaba s9254 digital servo . I think this should do the job. The servo's speed is 0.06sec/60 (@ 4.8V) . I have also added the extended tunnel wings and the tunnel flap to the cat . So soon as i have built this cat (New build thread coming soon) let the testing begin!!! Bonewar

[Arctic Fire]

.
The full size boat has a lot more weight and Power to make the flap work. In a model the flap will create a lot of lift because of the packing of the air in the tunnel. This air will build and move forward the longer you run in a straight line, until it blows over the front of the tunnel, causing lift in the front of the boat. To keep the lift in the back the shorter the tab the better and possibly opening up the vent in the step in the rear of the boat.

I agree, if you lower the tab you'll be creating one solid air packing tunnel. The air will flow down over the tab down and create some serious lift. I think the gyro idea would be awesome (digital ultra fast servos) to control a functional wing spoiler on the back. Set you angle for conditions, and let her fly.

Are there Tunnel/Hydro R/C's that have active wing adjustment (servo controlled, no gyro)? I can see it being helpful for 'tuning on the fly'

What about a micro servo to lift the Turn fins for straight liine performance with no drag?

This project is awesome by the way, keep it going no matter what we all think, the truth will be in the testing!!!

[bonewar]

Here is the 2nd version of the tunnel wing assembly.

I will post the results good or bad when i have the M12 up and running.
To finish this thread.



And the first prototype scratched!!!


Bonewar

[ozzie-crawl]

excellent craftsmanship as always rick,looking forward to see how it goes

glad to hear you got threw the cyclone okay,some big damage up that way poor buggers

[bonewar]

Ozzie,
Thanks mate,

Hats off to the brothers in the SES ,
They do an awesome job of helping the community.

I think the wing will work????


Only time will tell!!!



Bonewar

[bonewar]

This is where i'm up to with the tunnel wing.

She's going to turn out real nice.

Just hope it works as good as it looks.

Now to paint this hull !!!

Bonewar

[Jeepers]

Just hope it works as good as it looks.

Now to paint this hull !!!

Bonewar

umm...shouldn't you test it before you paint it. what if you have to cut up the hull some more?

[bonewar]

I think it will be OK.

Just on how much deflection i use on the wing will be key.

We will see soon.

Bonewar

[old guy]

Looks good closed in like that now. should have less drag. keep it up
Old Guy

[snaychev]

Nice job done! Cant wait to see that beauty on water.

[larryrose11]

Bonewar, what was the result?

[photohoward1]

That thread is 9 years old.


Sent from my iPhone using Tapatalk

[Fluid]

Yep. The OP hasn’t been back to the forum in almost five years......


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[Ralf]

I agree with randy.
I put such a tap on a 138 mystic which was extremly light, 7.8kg running 100-110mph.
The tab had no effect on the bow. It simply liftet the whole boat out of the water, running on the props only at 70amps per motor.
Nice but lot of risk.

I think it helps heavy boats lacking on lift. Helping to surpress blow overs not very much help.

[bonewar]

hi guys,
i thought i'd better come back and finish this M12 Cat.
This is where im at with it...192086107_1805127792993652_474868245117797552_n.jpg191330304_1436884930008580_6029607181139569850_n.jpg191517671_1165872393930189_2917570307827014486_n.jpg191571094_329370991910692_239319655111433984_n.jpg5586.jpg

[Fluid]

Glad you?re back with an update - but that last pic is over 10 years old….

F9D6B150-E526-4B44-B0D5-355507D5A178.jpg







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[bonewar]

Fluid, I took all the pictures of the Boats this morning mate.
They have been sitting in there wall mounts this whole time.
Just waiting on me to pick up interest in them again.
I love just looking at them.
They look Fast?.

[bonewar]

Hay I just noticed the date on the pic, I don?t no how that got in there.
Bit rusty on adding the attachments to my posts..
Good spotting mate.🤘💀

[hughb]

They look bloody fast Bonewar! Love to see some Aussie offshore cats, and they look like scale replicas too!

[bonewar]

cheers buddy.

[rufus2000]

I like the cat in the middle (the one with the simrad logo), where can I get one of those?

[Old School]

Just giving this some thought, why do cats have such large foredecks? Sailing catarmarans achieve some phenomenal speeds and utilise a trampoline forward of the mast to I presume prevent pressure building up under the deck. Some earlier models with solid foredecks even had blowout panels to relieve pressure. Could a power cat have a shorter foredeck to prevent excessive pressure build up prior a blowover or perhaps replace the foredeck with a spoiler to maintain a down force on the nose?

[NativePaul]

For speed in a straight line I believe. For a given amount of lift a long narrow tunnel has less frontal area and thus less aero drag.

I have built several cats with much shorter tunnels and longer pickleforks than is usual, as well as moving the centre of lift back closer to the centre of gravity, it also allows a wider tunnel for the same amount of lift, which was good for me as I wanted to prioritise handling as I was racing on a more or less square course at the time.

[Fluid]

Just giving this some thought, why do cats have such large foredecks? Sailing catarmarans achieve some phenomenal speeds and utilise a trampoline forward of the mast to I presume prevent pressure building up under the deck. Some earlier models with solid foredecks even had blowout panels to relieve pressure. Could a power cat have a shorter foredeck to prevent excessive pressure build up prior a blowover or perhaps replace the foredeck with a spoiler to maintain a down force on the nose?

Catamarans are air compression hulls, like hydros using air rather than just water to lift the hulls out of the water, reducing drag and increasing speed. Sailing cats don?t weight nearly as much as a powered hull of similar size, and when running with the wind there is less air passing between the hulls to be compressed anyway. It?s no surprise they lack large decks as they woukd provide little if any advantage.

Full-scale cats need long decks to trap enough air to counteract their weight, but model cats may not need as much particularly if they are very fast or lightweight. Like Paul I?ve built cats with shorter decks to move the center of pressure back to reduce drag while also reducing the risk of blowovers. One of these held the top cat SAW record for years. The downside is that the resulting hulls are just not as aesthetically pleasing as are scale models.




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[larryrose11]

I worked with a fellow in the past that was having lift issues with his cat. We came up with the idea of using a Diffuser like in race cars. It worked!! He got past the blow overs and was able to run his struts back down to zero degrees (previously a few degrees negative)
Difuser_3.jpgDifuser_4.jpgDifuser_5.jpg

[Steven Vaccaro]

I worked with a fellow in the past that was having lift issues with his cat. We came up with the idea of using a Diffuser like in race cars. It worked!! He got past the blow overs and was able to run his struts back down to zero degrees (previously a few degrees negative)
Difuser_3.jpgDifuser_4.jpgDifuser_5.jpg

Thats wild, how did you come upon that particular design?

[Fluid]

I can’t say what inspired him, but similar tunnel extensions have been used on a few OPC models for many years. I used adjustable trim tabs on several of my record-setting SAW cats which performed the same function. The faired tub is pretty cool.

FD10451F-E9FC-481A-9069-9F41E9428B72.jpegBBE199F2-1A08-45EB-B6DE-A45F2F2B65B6.jpeg

[fweasel]

Thats wild, how did you come upon that particular design?

That's Mike W's bulgarian cat. It's a triple digit, super stable runner and has a lot of body work done to it. He sectioned the entire hull and made it lower profile, in addition to the diffuser design Larry Rose came up with.