Airdam for shovelnose

[BHChieftain]

I'm messing around with an airdam for my 1/10 shovelnose. I am using 2 large drinking straws stacked on top of each other taped together, then taped to the hull.

Got a few questions--

How tall should the airdam be? I could replace the straws with an L-plexiglass design if the straws are too short.

How far back should the dam be placed in the tunnel?

Thanks,

Chief

[Fluid]

The height of an air dam depends on the boat, speed, etc. but the thickness of a single large straw works well for my Sport Hydros when they get flighty. I'd place it 2" behind the beginning of the tunnel.


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[martin]

Speak with Fluid as he uses i believe a single straw on this cat hulls, i know they fit them around 2" back from the tunnel but thats on a cat hull. Speak of the man & he shall appear, thanks Fluid.

[longballlumber]

Another item is a cutting a replacment wiper blade to the correct tunnel length...

Later,
Mike

[electric]

What do you recommend to attach the straw to the hull? Can you just tape it on to try it out? Not a theoretical question since my whip 40 took off again a few weeks ago.

[martin]

Yep just tape the straw all the way along its length, no need for more than that.

[JimClark]

the plastic angle works well some have used the clear angle you can get at home depot that protects sheetrock corners

[monojeff]

I just use clear hockey tape same stuff I tape the hatch up with.
Put two pieces together and can make it different heights.

Place one piece on the boat where you want it then fold it over. Then place the other piece ontop of the food and secure it down.
Instant removable air dame work great.

[BHChieftain]

Thanks for the inputs everybody. FYI I have been using clear hockey tape to attach the straws and it is very secure...

I'll try a single straw instead of the 2 straws on my next run.

Chief

[brushlessfreak]

i use a piece of 3/8 heat shrink tubing elec taped about 2in back from front in my catamarans and it works extremely well.the heat shrink tubing is a little stiffer than the drinking straw.it really makes a huge difference when getting over 50mph,in my opinion.

[electric]

I cannot wait to try out this straw thing to see how it affects the hydro. Let me ask the group a question. If hydro's are prone to flight at high speeds, why don't they have a "bump" in the hydro tunnel two inches back to resolve the "lift" issue? Especially if the is boat designed to race (50mph +)? Got two extra staws at lunch today. The waiter was perplexed why I asked for them...chuckle.

[Fluid]

Jim, some do have a "spoiler" in the design - Jesse's new wooden Sport boat has one for example. The best solution is to design less lift in the tunnel, but most of the hulls we use are modified nitro hulls which were never designed for the speeds we are now pushing them - the result is too much lift. The Insane FE-30 was designed as a P-Limited racer and has less lift. I only use a dam on my Limited-powered FE-30 in high wind conditions. With full P power it may benefit from one....


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[electric]

Jim, some do have a "spoiler" in the design - Jesse's new wooden Sport boat has one for example. The best solution is to design less lift in the tunnel, but most of the hulls we use are modified nitro hulls which were never designed for the speeds we are now pushing them - the result is too much lift. The Insane FE-30 was designed as a P-Limited racer and has less lift. I only use a dam on my Limited-powered FE-30 in high wind conditions. With full P power it may benefit from one....


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Thanks Jay, this is actually for my Q hydro. You will be seeing me with some straws shortly. When the whip 40 takes flight it is something to see.

[Fluid]

Yes, the Whips are not designed for FE power and have plenty of lift. Most of the time you can work around it, but given some windy weather....



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[detox]

It would be cool if we could build a windtunnel of some kind. A prop dyno would be cool also.

I am currently building a Whiplash 40 Q Sport Hydro. I will try to take out lift when building (leading edges sloped more downward, more weight in sponson tips, heavier batteries, strut adjustment)

[Fluid]

Be careful not to take out too much....it is a balance of weight and speed. Too heavy or too slow and you have a dog. Designing hydros optimally means designing for a relatively small speed window. Then we have the wind.........



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[BHChieftain]

Here's my latest attempt -- will run it tomorrow.

Chief

[Brushless55]

looking forward to the video on this.....

[monojeff]

I have mine about halfway between where yours is now and the nose.

[JimClark]

Should do the job

[BHChieftain]

I have mine about halfway between where yours is now and the nose.

If I get too much lift I'll try moving it forward from here.

Chief

[siberianhusky]

Tried the tape method on my Motley today, don't think it did a thing! Looked for some old straws in the truck but didn't have any. So far I like the wiper held on with 2 sided tape. Been working good for a while for me.
Had the same amount of porpoise with or without the tape, just a slight bob about the last 1/3 of the straight. Wiperblade and it was back to smooth and the amp draw went down 5 amps average for the run. No other changes at all.

[BHChieftain]

Decided to move the dam up a bit, see pic. Did 3 runs today-- worked really well. Ran full throttle in the turns, and even when the water got choppy with the other boats it stuck nicely.

Chief


http://www.youtube.com/watch?v=0Ps7MLkGdvs

[monojeff]

Nice work. Very close to where mine is.
Interesting the way your sponsons are.
Tweak here and there is what makes these boats run much much better.
6months of fiddling and finally feel like I have it where I want it.