New .12 Texan SAW

[GTR]

Hi Glenn,

There is another car pipe that you could try it is the 0.15 size paris pipe. There are a lot of aircraft 0.15cui pipes out there as all the controline speed guys use them. You could add an after muffler to one for quietness. I'm pretty sure Nova Rossi make a 180degree header if i'm reading ron's mail about the exhaust. You could also try the 21 size 180degree header from thunder tiger - might be a good size for a 15. (cheap also)

keep moving forward to those high speeds you're famous for.

GT 8)

 

[Glenn Quarles]

Thanks for the advice on the pipes! I am using an Associated header...it is really nice and comes at very reasonable cost. I would like to get my hands on a few different airplane speed pipes. I'm looking for RPM more than torque...the boat accelerates very fast, but reaches top speed in just a few hundred feet.

Glenn

 

[E]

Glenn, have you though of retrofitting a 2-speed tranny (like from a NTC3) in your boat?

Get the torque to launch on 1st and get the speed when the tranny kicks into 2nd. The new 2-speed trannies are more reliable and lighter than the old-ones. Might be worth a try...

Eric Perez

 

[Ian Inverarity]

Has anyone actually tried one of the two speeds in a boat? I thought about it years ago but have never tried it. One of the limitations was the reduction ratios for the car type 2 speeds was too great for what I wanted.

Ian.

 

[TimD]

Glenn,

Forget using a 21 header - the inside diameter is way too large for a 21 so it is even worse for a 12 or 15.

Personally - i'd be trying a pylon or speed pipe on it - they are set up to pull huge rpm's. I used to have one but I can no longer find the thing. It was tiny in the stinger area and had a nice rear cone shape to it - originally made for tethered cars I think.

Tim.

 

[Glenn Quarles]

Tim, you are RIGHT! I am a big believer in having the header ID match the case exhaust ID and the pipe ID where they come together. Too big of header is BAD.

The kind of pipe you are describing is just what I'm looking for...if any body has one laying around I would be happy to buy it.

Glenn

 

[Ron Olson]

Glen, I was wrong. I looked through an older issue of Radio Control Nitro and that pipe was a 2-piece. The first picture I saw made it look like a 1-piece. I ordered a MIP pipe yesterday that should be in today. It has the rear stinger as opposed to the side stinger. I'm afraid of most of those side stinger pipes because they are angled forward, if the boat dies andthe pipe is pointing downwards, it could easily pick up water into the pipe.

I was also thinking of when I get a front exhaust engine about putting the pipe so that it would be on the right side but got thinking that water from the turn fin might cool the pipe too much taking away kinetic energy. I might have the same problem on the left side but not so severe.

Any thoughts anyone?

Posting #501, now I'm a YaBB GOD! I promise to use my powers (none) for good, not evil.

 

[Altimat]

Any thoughts anyone?

Yeah mount the engine horizontally.

 

[Ian Inverarity]

Ron,

Congrats! Another God!! That makes four! ;D

Nitrocrazed racing: He's not the Messiah. He's just a very naughty boy.

 

[Glenn Quarles]

Well, I learned some really interesting stuff about my .12 hydro this weekend at our record trials. I started off Friday morning with my original boat (1 lb. 10 oz) and motor. While the other guys were getting ready I ran once just to see how the needle was…the boat ran and sounded better than it ever had…man I thought I had it made! Wrong! Not 5 minutes later with all the necessary folks working the clocks I launched again and it made about half a pass then started to fall off. Fast forward a few hours. It has only gotten worse with the boat barely able to even launch.

OK, time for plan “B”. I run home and get the motor for our new boat, one of the new Sirio Outlaw’s, and put it in the old boat (I knew this boat worked good) to see what I could do. Fast forward another hour and I had got the motor broken in and was trying to make it run fast, but NO DICE. The same boat, pipe, prop…everything that had been easily running 75+ was now running maybe 50 with a brand new engine (100% stock at this point).

OK, time for plan “C”. Since I was getting nowhere fast and the water had been perfect glass all day I thought I would try the new boat (1 lb. 4 oz) to start checking out how it was going to run. I took the Sirio, and pipe out of one boat and put it in the other with a V937 and gave it a toss. WOW what a difference! The first pass was up around 70 and the boat was working great. After a couple more passes I brought it in and put the 2137 on it (the same prop I had been using on the other boat) and tossed it in again. Within a couple passes it was up around 73 and I had a couple of consecutive 2 way passes around 72 mph for the new record. Since this project has been for my son Ross to set a record, and he was still at school, I stopped running the boat certain that he would easily push the speed past where I had it.

So, back to what interesting stuff I learned. You may know I talk a lot about how important weight is, but even I was completely surprised by how much difference 6 oz made (of course this is about 1/3 of the total weight of the boat). It is obvious that it made enough difference for the motor to be able to get to the RPM where it turned on and really started working. Same engine, pipe, and prop…almost a 25 mph gain…I was shocked!

Fast forward to Saturday. I modified the engine very slightly…I smoothed some of the angles leading into the intake ports, but left the timing the same, I changed the exhaust timing by about 5 degrees, and smoothed the edges on the intake port of the crank which opened the timing a bit. I also took out the one head shim that was in the motor (I don’t even know what the head clearance is, I just knew it was too much). We didn’t get enough really smooth water for me to figure out what I needed to do to go faster, but Ross was able to get a fast time of 73.481 and a 2 way average of 72.863 mph to get the record.

In hindsight I think I needed to put a little more pitch in the prop. The boat sounded like it was really screaming, but still didn’t go as fast as the other boat did in the past. I think the prop was riding just a little bit higher on the light boat and needed a little more pitch in the tips to turn some of the RPM into MPH.

Incase anyone is wondering what my opinion is of the Sirio…I still have some work to do on it, but I don’t think it will ever be as strong as the modified Nova. Maybe I will find that I am wrong, but comparing it to how the Nova ran in the old boat and how it ran in the old boat it just doesn’t seem to have the HP…it did turn more RPM than I ever got the Nova to turn though. I guess I need to put the new bearings in the Nova and stick it in the new boat to see how it does.

Sorry for talking so much, but I just wanted to pass this along, maybe it will help,

Glenn

 

[Glenn Quarles]

I don't know what all the #8&$5$7682 code stuff is about on my last message...well you should still be able to make out the story.

Glenn

 

[Ian Inverarity]

Glenn,

Why do you think the original boat went off from the first run you did on the Friday morning? What changed to make it go worse? ???

Congrats for you and your son getting the record! ;D

Why did you change from the Novarossi to the Sirio?

Ian.

 

[Don Templeton]

Congratulations Glenn,

Sounds like you've got it all together. I can't wait to hear what it does when you get that Nova back in it.

You've just got to get a digital camera! I love hearing all your accounts but we need pictures. ;D

Keep us informed,

Don

 

[TomMoorehouse]

Great job Ross and Glenn!

How much did you say that boat weighed?

 

[Ron Olson]

Congrats on the record! Gary has too many anyway.

 

[Hammerhead]

Glenn! I will be getting a sirio soon for my kit HH.12. I would like to see some pics of what you did to the ports. If possible, that is. Please take some snap shots the next time you take it apart.

Also, Have you ever tried a 215. I get a lot more bite with mine than a V937. I know that some people just don't like prather props. My HH.12 is a little light in the tail so the V937 really didn't like staying in the water. I was getting high 40s and low 50s with the V937 where I was getting 58-59mph with the 215. I'm running a heat racing configuration at about 2 and a half pounds wet. If your not so dedicated to not using Prather props like I know some people are, I would really like to see what the results would be in a SAW set up.

Thanks, Hammer

 

[Eric Perez]

Hammer I think the problem with the S215 is that there is not enough pitch to reach SAW speeds.

The lift on the V937 could be reduced with the right prop mods.

How can you not be light on the tail on a 1 lb 4oz. boat? Maybe Garry has his engine mounted over the prop ;D

 

[Don Templeton]

Hi Glenn,

You've got me completely confused on how to build a light .12 rigger. I've done some weighing on my digital scale and this is what I come up with.

OS .12TR engine with 4/40 mounting screws, hex flex, Associated manifold, spring, Mac tuned pipe with coupler, starter belt, .130 flex shaft, stub, nut and 215 prop, 4-AAA nimh batteries, 2-micro Hitec servos, micro Novac receiver and switch.---- ( 16.5oz )

Help me out here. How in the world do you build a boat that includes- a tub, front sponsons, hatch cover, engine mount, rudder, turn fin, stuffing tube, strut barrel, booms, fuel tank, pipe hold down, and assorted linkages with only ( 3.5 ounces ) to work with?

I can't figure out where I'm going wrong!

Thanks

Don ??? ??? ???

 

[Glenn Quarles]

Hey guys, sorry I haven't been on in the last week or so...the Air Force has me on the road and I'm just getting time to think boats.

I will try to answer the all your questions, but if I miss one please ask again.

Ian, after the first run I think the bearings started to go...I guess with the 1,000,000,000 rpm the thing has turned it was time! I had to switch to the Sirio because I couldn't find a Nova to buy. I think the Nova is better from what I've seen so far.

Tom, the boat weights 1 lb 4 oz RTR (that even includes the muffler on the pipe) on the Post Office scales.

Hammer, I will send pictures of the port work I have done, but like I said before, I don't think it did much good. I really need to check the timing and adjust from there.

Eric is right...the Prather props do not have enough pitch for SAW. The hopping is not caused by the boat being too light in the tail...Eric is right again, I don't know how much tail weight I have, but it is not very much! The amount of lift a boat likes is a very fine balancing act. Prop design, strut angle, and boat weight all have to work together...if the boat is too heavy to allow these kind of high lift props to ride up on their tips like they try to do then the boat will hop. This discussion can get deeper, but I'm not sure if anybody is interested.

Don, it sounds like you are weighing a lot of the right stuff, but there is still room for improvement. For example, how long is your pipe and header (shorter = less weight)? Small Octura hex? Starting belt (I don't think mine weights enough to show up on a Post Office scale), Stainless prop or brass (as you know the V937 and 2137 are VERY thin and light), AAA batteries...WAY to big, switch...what switch...I don't need no switch. Hatch cover...again no, motor mount...I didn't weight mine, but it is much less than 1 once, turn fin...none, strut...none, and I use sub-micros with the mounting ears cut off.

I only weighted this boat one time before I finished it and it was 6.0 oz with the complete boat and hardware. The engine weighted 5.9 oz as it came out of the box...aircooled head (I don't use it) with no flywheel or carb.

To build really light you must ask yourself about EVERY piece that goes on your boat. AND you have to figure out if that piece is even needed! This is another subject I could spend more time on.

Well guys, I gotta go, I'll check back later,

Glenn

 

[Ian Inverarity]

Glenn,

Which 12 Nova do you use? The side exhaust marine or one of the air-cooled hi-po car types?

I am interested in what you have to say about prop hopping. I have a fairly light (8.4 lb) 90 hydro that runs well in calm water but hops a lot more than I would like in rougher water. It loses so much drive hopping that I lose about 20k in speed, and the props bend. The boat has two rear sponsons, but the bottom of the strut is set below the sponsons, and it is a round bottom strut.

You seem to be implying that the hopping occurs because the boat is too heavy? I would like to run the boat so that it could run thru the chop a bit more rather than boucing over it so much!

Ian.