OB Madness

[user 115]

RE: the last post.........

As soon as I can free up some space I will post the photo of the gearboxed IMPBA "A" [.12CI-2.5CC] SAW boat rigged and ready to go.

It ships out today to Alabama to David Hall for testing and set-up for the SAW trials in Huntsville in April.

This is just a good start....more to come,which we will share with you later,from the GPRC "skunkwurks".

Man, who woke up Geraghty??? Glad to you see so interested again, Rod. Burnin' the midnight oil in Mondovi, that's for sure!

Take care,

Charley

 

[topfuel443]

Thats awesome....

Dont know what else to say. Hope it works as good as it looks!

~James

 

[Jerry Wyss]

Yeah Rod!, Man, You just made my coffee taste better :lol: :lol: I was "trollin'" for ya,

Tryin' to catch the "Wopper"!

I had the honor to see this beauty early on and it just put a Big smile on my face,,

That is a "Frankenstein" if I ever saw one,,Beautiful!

The tuned pipe will rattle your marbles too,,,I swear, The Man "Lives" outside the Box.

 

[Geraghty]

Thats awesome....

Dont know what else to say. Hope it works as good as it looks!

~James

The gearbox sat there and ran on the pneumatic die grinder handpiece for an hour at about 50K breaking in the gears and the only thing that got warm was the grinder.It is as smooth as a baby's butt.

I am confident,mechanically, it is going to work great,all David and I have to do is learn how to use it.

 

[JoeWScott]

Pictures, Rod, more pictures, I'm dyin' to see the hull!!!

JOE

 

[VansRacing]

Looks good Rod...does this mean you are going to be in Huntsville in April?

-Carl,

 

[user 115]

Rod is sending me pics.. I'll get them posted when I get them.. It's a sweet little boat!! One he's had for a long time..

 

[user 115]

Pic 1

Pic 2

 

[Tim_Duggan]

The moment I saw the OS 30 engine I instantly thought it would go well on a TT lower........ Seeing the combination put together sure put a smile on my face. The next questions will be (1) what pipe works, and (2) is the TT driveline up to the load of the bigger props etc. The flex cable and propshaft assembly in particular.

Rod,

Awesome piece of engineering! I truly believe gearing is the way to make small engines really come into their own. I don't think I would have done anything different to the way you have done the conversion.

I'd love to know roughly what RPM you have the engine / pipe combo configured for - the small engines are capable of some great rev's......and the gear reduction helps to capitalise from them without resorting to tiny props.

From my experience with geared O/B tunnels, I found that the higher reduction ratio's with high pitch props induced some really wierd handling traits, but also gained some good speed. Admittedly at the time I knew nothing about prop tweaking.

Please keep us posted on it's progress.

Tim.

 

[Jerry Wyss]

Yes, It was Tims idea,,I was lookin' at other engines like the Ofna's and such.

The Ofna Hyper .21 looked good until I saw the removable pin that would

drive the TT PTO.

After talking with Rod 'bout threading the counterbored crankpin and installing

a hardened screw it's looking possible again.

I also bought a Ofna Force 4 port along with the other two,,, but after looking

it over I can see it's less desireable than the original TT engine :lol:

My next investment has to be some machinery,, lathe and mill,,otherwise I'll

be driving all the machinist within 2000 miles nut's :lol:

 

[Geraghty]

Looks good Rod...does this mean you are going to be in Huntsville in April?

-Carl,

Carl,

I doubt I will personally be there but David will be there for sure.

Rod

 

[VansRacing]

Well, it has been awhile since any of us have seen you. I think the 99 Nationals maybe??? Not sure about that date but that seems about right. Well, david will have our complete support if he were to need anything to get his time. From what we have seen, I am sure that comming off your bench, that little engine will be packed with extra RPM's!

Good luck to the effort!

-Carl,

 

[Geraghty]

Thanks.......I will be at the Internats in Evansville.

 

[Ken Retallick]

Nice work Rod!

Now you and i know which engine really should be bolted onto that box... wouldnt scream, but more like a whistle....

Ken

 

[Tim_Duggan]

Thanks Rod,

Even at 36krpm (which for a hot 12 engine like an NR, is conservative IMO) the prop speed with 1.33:1 should still be right up there with most 21 engines and the torque multiplier from the gear reduction should allow some decent sized props. It should be capable of running some very good numbers!

 

[Ronald van Essen]

You think that's sumthin', there's a member on this site that could go "All In" on this one, fer sure

He may show ya,,,,

From the GPRC "skunkwurks"

A "quick-change" gearbox for an assault on the "A" SAW record.

This gear box looks much smaller in size then the one Bob Kensill showed us some time ago on his outboard.

Cannot find it on this forum anymore.

Ronald.

 

[james irwin]

Pulsetech, I looked all thru OS home Page "engines" and "carb" section

and the problem was they didn't have a listing of "neck" and "bore" sizes

on all of them,,,that made it a little difficult to find the right one.

Funny thing is they had one listed for a 90 airplane engine that read

"If you use this carb, you're on your own",, :lol:

that really cracked me up,, that is actually written there.

HEY JERRY , NICE JOB, YES I DO LOVE THOSE AIR COOLED HEADS ? BUT WATHCH THEM THO , AS THEY CAN STILL RUN TO COOL. I SEE YOU SAID YOU CAN REMOVE ALL BUTT THREE FINS/ YOU DONT RUN 60 % DO YOU . B) :lol:

 

[Jerry Wyss]

As a Matter of fact Jim I do run 60%,,, is there a problem with 60?

Thanks for the comment,, I've done very little on it myself but theres

other stuff to work out yet, bolt holes that mate up the mounting lugs

are way off from where it bolts to the steering arm brace.

Gettin' the right pipe is gunna be a hurdle,,frankly a near stock Gadget

Craft with a .300" short stinger might be better than the junk that you

would normally put on it if it went on a RC car.

A real pipe might really wake that thing up too,,it has a 9mm carb bore,,,

.300'' exhaust opening dosen't sound that unreasonable, yeah :huh:

Really, won't know until I measure up the timings and run the pipe formula.

 

[Duck899]

There's a new girl in school,,and She's Perdy

Didn't think it was going to be an engine..... :lol:

Bad picture of her though

 

[izitbrokeyet?]

verrrrrrrry cool Jer,

She got a name?

Should have torque to spare……..put a big pitch prop on that lower bro...... if memory servs…theres a low limit on prop diameter. thinking around 41mm is tops...please correct me if I'm wrong.

I respectfully submit....."Bride of Frankenstein" as a name B)

KB