New .12 Rigger Nitro Trident SR

[Don Templeton]

Eric,

That really is a unique design. Is the whole rear end a foam block? Are You going to try a V937? I've been told they have quite a bit of lift.

I cant believe you got all that radio gear in such a small space!

 

[Ron Olson]

Eric, I'm glad that someone else is thinking the same as I am. I figured that with the speed that the boats are running and with cooler air plus some water spray the engines ought to run cooler than in the confines of an R/C car or truck. Cutting off half of the fins should drop some weight plus get the temp up where it should be, around 230 degrees.

 

[TomMoorehouse]

hey eric.... we going to put up a page for that project?

 

[Eric Perez]

I worked on the CAD prints last night. Got them all cleaned up and put in all the needed dimensions.

The balance point is smack on the middle of the 3rd boom, the one that supports the turn fin mount.

Tom, as far as an article? Still need to do some needed R&D with props and strut adjustments. I have all the pictures need for a how-to-build article...

I will e-mail you the CAD prints in DXF this weekend.

I've been working on a re-designed sponson profile similar to the Gillmanator SAW boat -looks sweet...

Don, the boat "is" a big piece of foam. I ended up using a metal geared mini-servo for the rudder and a plastic geared mini for the throttle.

Here is a pic of the radio box. In the picture I'm charging the (5) AAA Nimh pack in the boat. I'm still not using a switch on the radio-box; it will be mounted on the radio box-lid.

Ron, On my other air-cooled .12 engines used on the water I ended up removing 2 of the seven cooling fins on the engine head. Got me a nice fat-sound on the shore and cleaned out good once in the water. Engine temps with an infrared thermometer where in the 220-250F range, plug had a nice dull finish.

Hope that it gets to 60F this Sunday, for more testing time!

Radio box picture

 

[Hammerhead]

That is looking really good Eric. Speachless :-X.

Can't wait to see videos. Hammer

 

[E]

Hammer don't have a way of getting video unless it's on a VHS-C

I guess if you see plenty of photos you may be able to imagine it running!

Eric Perez

 

[Hammerhead]

Send a cassette to Mike P and see if he will post it for you. He helped me out with VHS before.

Hammer

 

[MikeP]

Hey Eric,

Good to see a project from the building table to the water. Nice work! I talked to MikeP and he said that if you send him a VHS he would get it posted here.

-MikeP

 

[Eric Perez]

New cowl, new tank, new pipe and new .12 engine.

It will be nice this weekend so I hope to test out the new power plant. I will brake-in the engine tomorrow or Friday.

Got tired of seeing the big hump from the tank. Got the new tank from a Traxxas Nitro 4-TEC it fit the hull like a glove. I think the Associated RC10GT or NTC3 tank will also be good candidates for .12 Riggers.

Now the boat is 32.7 oz. (plus fuel)!

 

[Don Templeton]

That's really cool Eric! Looks great now. What engine is that and are you going to cut off any fins?

Don

 

[E]

It's a PICCO XP Side Exhaust, with rotary-carb. They had a good deal at the LHS and it had a long-shaft w/ a side exhaust carb -Just what my boat needed. I'm breaking it in right now, It's giving me fits but it's nothing that a 14V starter can't handle...

As far as cutting fins, I'm having a hard time getting this thing just to idle and stay under 200F -only time will tell if that beautifull blue anodized head will get the hacksaw treatment :'(

Eric Perez

 

[E]

I meant to say rotary-carb, standard side-exhaust

Got the engine all fired up, just needed to blip the throttle to clean out the pipe every once in a while. The pipe is at 10.5" and it's still too long get's on the pipe almost as soon as you start to work the throttle ;D

Eric Perez

 

[Propjockey]

Eric -- what dia. is the header?

 

[E]

The header and pipe are 1/2" ID the pipe length from glow-plug to center of plug us about 9.5".

The header is Macs 2.5 for marine engines

http://www2.towerhobbies.com/cgi-bin/wti00...p?&I=LXZ605&P=7

and

The pipe is a Macs 2.5

http://www2.towerhobbies.com/cgi-bin/wti00...p?&I=LXZ557&P=7

Eric Perez

 

[Eric Perez]

Update on the Nitro Trident SR12

Tested out the Picco XP12 engine. Ran real good, started every time without missing a beat. Launched everysingle time and came back to shore on every outing.

The outside temp was near 70, and the engine head reached 230F. I re-adjusted the main needle to keep the head-temp close to 220F. This is a good racing temp. At this setting the engine was very consistent and the plug was happy.

I was happy too because it means I can keep the XP's shinny blue anodized head away from the hack-saw.

Still have to figure out what to do with the starter-belt. The belt was rubbing the fly-wheel and it broke. I think that a velcro strap will do the trick... any ideas?

The boat was radar clocked at 38Mph -but that was with rudder input to keep the boat going straight (Hammer -I know you gave me the dimensionss for the off-set front sponsons, but it was too late. I had already cut the booms to my original dims). My next boat will probably have an offset strut and offset spoons.

38Mph Note: This is with Stock Picco XP12 15% Wildcat "airplane fuel" with 18% oil. Stock Prather S215 and MACS header and tuned pipe at 9.5".

Since the 38Mph run, I have shimmed the strut and it's turning much better. Speed is maintained in the corners and the engine almost idles in the water with the S215 in the back. I lowered the strut to where the bottom of the drive-dog is even with the bottom of the rear-spoons. Now the rears-spoons are not dragging on the water like on the photo.

The starter belt broke before the wife could take photos, so it must wait till next week.

Next run will be with the S220...

I'm running low on Octura supplies so it only sounds logical to get some more Octura props like the 3-bladed V937. I've been using Red-Locite/Permatex to attack the flex-cable to the prop-shaft and have had good success- are any of you running .12 riggers doing the same?

What other props do you guys suggest? Keep in mind my transom is lightly-loaded so lifting props are probably going to cause the rear to hop, like on the Hammer12 video.

Eric Perez

 

[Don Templeton]

Eric,

As far as the red Permatex attachment of flex to shaft, I wouldn't feel too safe with the red. The red is a thread locker! You need to use the "Green Sleeve Retainer" (3000psi shear strength). You will probably have to order it from a NAPA store.

Glad to hear the rear sponsons are out of the water now. I'm not really sure about this but just from watching the building and progress of your boat and where I think you CG is I believe you could get a bunch more speed by decreasing the angle of attack on the front sponsons. For sure you don't want any lift in your props. I understand from other posts that the V-937 might have a bunch of lift.

This is all just my thinking and doesn't come from an expert!

Very nice boat,

Don

 

[Eric Perez]

Don, you bring up a good point on the front AOA. My spoons are not adjsutable and they are not removable. If I focus on the last 2" inches of the spoons I may be able to modify them without having to remake new ones.

I think I'm killing speed by forcing the rear-spoons out of the water. This is why... I made the rear spoons with the same depth as the front sponsons. I'm basically forcing the front end down on the water. The boat is leaving a larger wake and there was more water spraying from the front sponsons than last time. The Nitro Trident is really a 4-point Hydro. Maybe the name should be changed to the Nitro fork ;D

What should the difference be in height between the front and rear spoons?

I thought that 38Mph was pretty slow for a .12 rigger. I must be killing speed in a couple of areas... I've only run the boat twice. Once with the TRX15-PRO and once with the XP12 -so there are still a bunch of things that can be done.

After I determine what the S220 will do I was thinking of putting a Hammer-cut on the front sponson to reduce the wetted area and maybe increase speed. I will be happy when I'm running 45 in oval trim.

I can already see that prototype #2 will have to occur sooner than what I anticipated.

Thanks for your input.

Eric Perez

 

[MikeP]

Eric,

It seems like the first boat is just to set a base line for the next boat.

People like Hammer that build alot of boats can get right on the first time, he also sticks to a design that he knows well.

38-40 mph used to be good for a .12 thats about all I got out of my first one but the bar has been raised.

How wide are the running surfaces of your front sponsons?

Also what I did on mine that helped the most was removing the rear spoons, this kept the hull out of the water but didn't change the front AOA.

-MikeP

 

[Don Templeton]

Eric, to my way of thinking (and probably only mine), if you use rears on a "light" .12 they should be at least 3/16" or more above the running surface of the fronts and the bottom of the strut should be about 1/16" above the fronts to start with. However this does not jive with what Hammer says and we all know how well his boats run. I do however think that if you can get the running surface of the fronts to more like 4 to 4.5 degrees max like Hammer says, it should free up the boat a bunch. I think that the rears should only be used to settle the boat. They are supposed to be 3 point hydros. (2 TEs and one prop blade) I do know that one of the biggest things to consider is props. They can make a hugh difference in boat attitude.

Good conversation. I wish some more people would jump in on this and let us know what they think. I just sit down and think about things like how far a blade will or should lift at speed like is it 3/4 or 1/2 or up to the hub. I just don't know.

One question I have for you- What is the depth of your fronts TE from the bottom of the tub?

Talk to you later,

Don ???

 

[Eric Perez]

Hope I don't put anybody to sleep here -but the local boat club is really not into scratch-building or boat designing... If I hear the phrase "put a .21 in that thing" one more time I'm going to scream

The depth of the front spoons are 5/8" same as the rears. The front spoons are 1.5" wide the rears are 1/2" wide

I ran the boat again this afternoon, ran the strut 1/8 above the rear spoons and the rears where still running out of the water. This loosened up the fronts sponsons and the boat started doing the rigger dance.

Rigger dance: Very light tapping of the rearmost portion of the front spoon(running surface). The spoons do a little dance left and right, at a relative fast rate like tapping on a pair of drums. There isn't much water deflected as it does this. The hull is basically flying over the water, only the prop is in the water all the time.

I think the "rigger-dance" as I call it is caused by:

1. high AOA of my spoons, they want to make the front climb out of the water.

2. The ride pad is too big, the spoons are 1.5" wide. I think that a width reduction via the hammer cut would be a step in the right direction.

What do you guys think?

I've built a couple of riggers and they have all done some type of rigger-dance.

The .21 riggers that I've seen run don't really do the "dance" at least not that I can pickup.

One more thing, I slapped the S220 on the boat didn't even re-adjust the strut. Launched with no problems, the engine was operating at lower RPM's -yet still ran well. No problems in the corners. Still need to do more testing.

Thanks

Eric [Rigger Dance] Perez