Kevlar and CF over foam Tunnel project

[MikeP]

Yup, I ran it, I am happy with it the hull. I just need to work out the steering problem. It acts like a weak servo. It would be nice if it handled the turns like a rigger ;D

-MikeP

 

[wswatzell]

What do you have for a steering servo in it? You are using a Kevlar woven string as a pull-pull setup right? Dumb question, but maybe the string is stretching. I know that Kevlar has a high tinsel strength, but maybe the weave allows for some stretch. I’m just guessing.

 

[MikeP]

I pretty sure the servo is weak, it's a 100oz Airtronics. It doesn't feel strong when you hold the motor. I am going to get a new Airtronics 200oz and make a smaller wheel for the pull pull. I want some grunt when I turn.

The Kev cord is stranded and doesn't stretch. I couldn't break it, pretty tough stuff.

-MikeP

 

[MarkScott]

Mike,

Yea, I'm certain the glass (storm window) won't fit inside the bag. While I was searching the web for vacuum bagging information, I came across one site that didn't use a full bag. What they did was use clear .004" visquine plastic, with "strip caulking" to seal it. The plastic I have, but needed to find this Strip Caulking. Just got back from Home Depot and picked up some replaceable Cord Weatherstriping. Believe this is what they were trying to get at. I'll be heading downstairs here shortly to try to make my first mold, but with a test cowl...

More shortly...

Mark..

 

[Slideblues]

Mike, I run JR radios and their Z4750 BB@ 96 0z/In, Never had a problem turning a "lite hull/mod motor" combo,

Are ya sure its the servo? Was it new or used?

Gene ;D

Oh yeah, How was the speed? 8)

 

[TimD]

a 100oz servo should be fine - how are your batteries?

 

[MikeP]

Here is what is happening, I go into the corner back off the throttle to set it up for the turn, giving more and more steering input to try and make the corner about half way around ( now in lane 4+) it hooks.

I know 100 oz should be enough but I don't think the old servo has it in it any more. It's left over stuff from my RC buggy days. It's a 94157 Airtronics. I had problems with the other one just like it in the .84 rigger. Same problem in the corners. The servo is weak near the center and stronger after it turns a little.

I got speed ;D Tim's OS is sweet.

Prop shaft is set at 0deg. 1/8" up.

CG started at 9.5" now it's at 9"

-MikeP

 

[TimD]

I had a similar problem which came back to a linkage geometry issue.

I have to admit I wasn't using a setup like yours with the kev-cord.

Maybe Grimmy can shed some light on it?

 

[MikeP]

Need some advise on steering, is the pull pull system good?

I am going to get rid of the Kev cord, should I stick with the pull pull or go with the solid rods.

Also could somebody tell me how far out on the servo arm do they mount the linkage.

-MikeP

 

[MarkScott]

Mike,

As for solid rods, the closer to the center on the servo arm, then there is more torque applied. Hopefully the problem is not the pull pull / kev cord system as I've spent some $$ to get them.

Mark..

OB Nut Racing: Applied Leverage to Motivate the motor

 

[MarkScott]

Mike,

Got a question for cowl creation.. The mold is currently cureing. Instead of using CF for the mold, I used about 5 layers of 5oz fiberglass. Hopefully the FG will be strong enough to be used for a mold. Would you suggest using the vacuum system to create the actual cowl or laydown process? I'll do this during the weekend. The Very Slow hardner states a FULL cure is 3 - 5 days.

Mark.

 

[Slideblues]

Here is a shot of the wheel Mike Z. used from the Villain buildup CDR:

 

[Slideblues]

And the measurement:

 

[Jerry Dunlap]

Re: Steering System

I utalize two solid rods in a push/pull steering configuration. I split the rods, overlap them, and then bind them together with a collar. Steering linkage adjustments are simply a matter of loosening the collars, making the adjustment, then retightening the collars.

Re: it hooks

If the boat still hooks after replacing the steering servo, you may need to install stumble blocks - if you haven't already done so.

Re: how far out on the servo arms

I usually run in the second hole out on my servo arms.

JD

 

[MikeP]

Oh! I think I am out in hole #2 area. Hopefully it's just too big a wheel. I think I will make a little bitty one and see what happens. The EPA on the radio is cut back about 50% so I should have plenty to work with.

Mark, I don't waste CF on molds. I like to find cheap heavy fiberglass for that. I use a couple layers of 5 oz. to start with and lay it down good and tight. Then pile on whatever is laying around( scraps, some 10 oz mat ect)

I suggest using the vacume bag.

One reason I didn't use the vacume bag to make the cowl on mine was you have to brace and support the mold or the vacume bag will bend and distort it. The way you got the non bag system it might work out better. Give it a test in the bag and see what happens then decide.

I use a electric blanket to cure the epoxy. I haven't had any problems after waiting overnight. When I made my cowl I set it in the sun for a couple hours because of the black CF it gets really hot and cured it quick. I try to wait at least a week before getting fuel on it..

-MikeP

 

[MikeP]

Well you posted more info while I was typing. Thats the same wheel I have. You wouldn't happen to have a picture or measurement of the linkage at the motor would you?

Thanks

Mike

 

[Slideblues]

Here is the radio box exits:

 

[Slideblues]

With a straight shot back to a K&B stering arm, dont have one here to measure :-

 

[MarkScott]

Mike,

How does the kev-cord exit the radio box? I saw the nipples use to seal the water out, but is there anything else there to support the cord?

Mark...

 

[MikeP]

No support straight off the wheel to the motor. Wouldn't think it needs support unless it changes direction.