.21 sponson specs

[dwilfong]

You must also take into account that changing the boom tubes also changes the top angle of attack.

The top of the sponson is the aero part that will help balance the upward force of the hydro lift from the bottom angle .

It is a balancing act.

Some times a new sponson with the bottom angle changed will yield better results.

moving the boom tubes will only get you so much. You will also have to move the back hight of the ski or rear sponsons to level the tub.

The smaller the boat the more sensitive it all is.

I think I got it all right. :blink:

David

 

[anthony_marquart]

What do you mean "why even ask for input".. Is it not the purpose to talk about it and ask questions? Physics tells us that the higher aoa you the closer the forward load gets to horizontal, which would be total plowing..

I ask for input because I want to learn,.. what was the purpose of your comment? The JAE runs less than 5deg AOA

Your thoughts on this are not correct Anthony

Think of the front sponson as a wing more angle = more lift

is your boat plowing in the rougher water or all the time ?

If its just on wind up your tub height might be marginal ( Low )

Water sticking to the Tub Bottom will make it plow

Greg

What does an airplane do when it's at slow speed and the pilot pulls up? the wing looses speed and lift, then experiences what many pilots call MUSH,.. it's not quite a stall but it's not climbing and may be decending,.. same thing as plow on a sponson. Keep going at this angle of attack and the wing will stall. Bring the nose down and and the wing can gain efficiency, lowered the AOA. I have a sneaking feeling that the symptom I am calling "plow" is not the same thing you guys are thinking of.. I think my terminology is incorrect. That would explain alot of this for me..

 

[RodneyPierce]

Greg, I was conversing with Anthony earlier, and he is talking about when your milling with the boat, you can see a little bit of spray off the front of the sponsons. I dont think I would really call it plowing. Just "wet" when not at speed.

 

[Charles Perdue]

What do you mean "why even ask for input".. Is it not the purpose to talk about it and ask questions? Physics tells us that the higher aoa you the closer the forward load gets to horizontal, which would be total plowing..

I ask for input because I want to learn,.. what was the purpose of your comment? The JAE runs less than 5deg AOA

Your thoughts on this are not correct Anthony

Think of the front sponson as a wing more angle = more lift

is your boat plowing in the rougher water or all the time ?

If its just on wind up your tub height might be marginal ( Low )

Water sticking to the Tub Bottom will make it plow

Greg

What does an airplane do when it's at slow speed and the pilot pulls up? the wing looses speed and lift, then experiences what many pilots call MUSH,.. it's not quite a stall but it's not climbing and may be decending,.. same thing as plow on a sponson. Keep going at this angle of attack and the wing will stall. Bring the nose down and and the wing can gain efficiency, lowered the AOA. I have a sneaking feeling that the symptom I am calling "plow" is not the same thing you guys are thinking of.. I think my terminology is incorrect. That would explain alot of this for me..

Anthony, the sponsons are a long way from being any kind of wing. The wedge shape is one of the most critical and unstable designs there is to try and manage airflow around. After playing with different designs, I have completely gone away from the wedge shape for sponsons. The ONLY advantage for the wedge shape is in being easier to build.

Charles

 

[Chris Wood]

Hi charles

hope all is well down SOUTH.

while we are on the topic of this.. i have wanted to enclose the tubes all together for some time.. have you ever messed with that and is there any effects or ILL effects to this. i agree with you on the sponsons.. just wish there was a CHEAP EASY way to vaccum bag them. I no nothing about bagging but i would like to as have some ideas to try some day

chris

 

[RodneyPierce]

Chris, I wish I would have known that!! Right before work moved to our new building, we threw away a killer vacuum pump. I almost grabbed it, but didnt know what to do with it. We used to use it to pull vacuum on neon glass. Im sure it would have pulled plenty of vacuum to bag parts.

 

[Ron Zaker Jr]

Hi charles

hope all is well down SOUTH.

while we are on the topic of this.. i have wanted to enclose the tubes all together for some time.. have you ever messed with that and is there any effects or ILL effects to this. i agree with you on the sponsons.. just wish there was a CHEAP EASY way to vaccum bag them. I no nothing about bagging but i would like to as have some ideas to try some day

chris

I think Mark Grannis was messing with bagging(or vacuum forming) sponsons a long time ago,maybe Doc and Mark B also.

 

[Chris Wood]

hey z

ya i know doc and mark do. i just don't know how to make them so the sponsons tubes stay in place?

maybe someday if i ever get time or money lol

 

[Charles Perdue]

Hi charles

hope all is well down SOUTH.

while we are on the topic of this.. i have wanted to enclose the tubes all together for some time.. have you ever messed with that and is there any effects or ILL effects to this. i agree with you on the sponsons.. just wish there was a CHEAP EASY way to vaccum bag them. I no nothing about bagging but i would like to as have some ideas to try some day

chris

Hello Chris, this morning, it feels like you guys up north sent us some of your weather. We had our first frost of the season.

On making sponson tubes, I use the airfoil shaped aluminum tubing from Tower Hobbies for the airfoil shape. I fill them with different sizes of CF tubing, starting small in the front of the aluminum tube, larger in the middle and small againt in the back, using vinyl ester resin to bond them into the outer tube for stiffness.

In my opinion every bit of drag and instability that you can eliminate helps.

Vacuum bagging of the sponsons is one way of making them. Another way is to shape them from balsa blocks. I use the balsa on prototypes to find the shape that I think that I want and seal it with epoxy. It is quick and easy. Still another way is to sand your sponson shape from H 60 or H80 foam and drape the CF over it, pinching it tight at the bottom and then applying the vinyl ester or epoxy resin. Use twill weave on the 3 oz CF and cut out the peices on a 45 degree angle, this conforms to compound shapes and drapes very easy. Then just sheet the bottom of the sponson in the normal manner.

Vinyl ester resin is more brittle than epoxy but it is also stiffer.

Charles

 

[Chris Wood]

cool thanks for the info charles and you are SO VERY WELCOME for the GREAT WEATHER you are having. specially since it was a balmy 26 this am here in the frozen tundra LOL!!

i will have to look into it some time

sorry to get off topic anthony

 

[Charles Perdue]

cool thanks for the info charles and you are SO VERY WELCOME for the GREAT WEATHER you are having. specially since it was a balmy 26 this am here in the frozen tundra LOL!!

i will have to look into it some time

sorry to get off topic anthony

I have been playing with different shapes made with different methods for a long time. If you need more detailed info just give me a jingle.

Charles

 

[Terry Keeley]

Vac forming ABS would be even easier I'd guess...

 

[dwilfong]

We are in the proses of building CF foam core sponsons. Have come up with a new system.

You need a mold to start with. vacuum bag CF in the mold. then put some release agent on the in side of the piece with it sill in the mold. do this to both pieces of the mold. you will need a top and bottom two piece mold for this to work.

Then bolt the two pieces to gather and fill with foam. now you will have a foam plug for the core with the right amount of under size.

Pull the bagged pieces out and save.

Then take the CF wet it down and wrap the foam core. put the whole thing in the mold and clamp it together.

compression molding we call it. works like a charm.

once you have the mold and the bagged pieces it all goes real fast. should be great for production.

David

 

[Charles Perdue]

The sponsons on this boat were done with the CF draped over foam method. The hull and cowl were vacuum bagged.

Charles

 

[Charles Perdue]

With Paint.......

 

[ALLAN YUEN]

With Paint.......

WOW NICE FASTEST Boat "' Stealth UFO"

 

[David Bryant]

Vac forming ABS would be even easier I'd guess...

wow that's absolutely beautiful! Would like to see more of this type of vacuum-bagged CF fabrication come along for complete construction of outrigger sponsons and hull/tub. I don't see why not? What are you using to create the initial "plug" from? solid block of wood? Also what is the vertical sheet material glued inside sponson? And that's to provide some structural support for boom tube I assume (once drilled through from side)?

 

[dr gary turner]

With Paint.......

Charles BRING THAT "THING" to Huntsville Nov 11-13 and run it through the lights. DOC

 

[Terry Keeley]

With Paint.......

Very cool!

 

[Charles Perdue]

With Paint.......

Very cool!

Terry, comming from the carbon fiber master, that is a real compliment.

Thanks, Charles