OUTLAW EAGLE MANUFACTURING

[Guest]

Posted this as a joke to see who would comment but until karey spilled the beans no one really did
Anyway details have been posted below

Xero

[Itsworthit]

As in turbine fast?

[TOP DAWG]

Or turbine slow. I'm no expert but from what I know of these things, they make big power for their size and weight but at part throttle they have very little power. In a Helicopter when they fire the thing up, it has no load on it. They warm it up then run it up to full RPM ( with no load ) and set the govern to hold this RPM they then start applying load to it with the rotor pitch and lift off. The Turbine is always at constant RPM no matter the load. How is this going to work on the Whitecourt circuit. Good Luck. Like I said I'm no expert but I do know they won't rev quickly under load, it's the boost that's generated in the compressor side of the turbine that makes power and if your not reving you have no boost.

[RPM]

Dawg have you looked at nye.ca he has built a couple of turbine boats , the latest being a eagle sport ! He has built a drive adapter with a brake that holds the output side back so the compressor can stay spooled up for instant response . I thought a variable pitch hydraulic torque converter could be built to allow the turbine to stay spooled while reducing the output shaft speed to the jet ?

[Xerophobic]

Ive been in Mark Nye's Squirt 2 and believe me that boat accelerates like a bat out of hell!
The brake rotor arrangement he designed locks down the free turbine shaft for docking and maneuvering. The turbine would otherwise put out 40+ HP at idle and makes docking etc tricky. Apparently that system can hold the output shaft(N2) still until the N1 turbine reaches approx 40% throttle before engine damage would start to occur. I do not believe this is why the system was built as with a GT there is no "turbo lag" as there is in a turbo charged car. The combustor rotor and compressor rotors are on the same shaft and must spin together at the same rpm.
Dawg is right that GT's have internally governed fuel controls which are very complex units. I'm not sure I agree 100% on the no power until they are spooled up. Its a little more complex and difficult to explain with a free turbine system in that the output shaft is NOT connected to the main shaft of the turbine. This in effect creates a viscous coupling of sorts between the 2 shafts in the engine. That added with the fact those shafts are not running at the same rpm AND one has a significant gear reduction unit on it and it makes it all hard to compare to the typical RPM analysis one is used to with a piston engine.
That said I did not notice any unusual characteristics going for a ride in Squirt 2. Ok ok I'll admit the afterburner display was a bit odd! Well that and it was bloody fast

Anyway this is all just my opinion about what I've heard

Cheers

[sandman]

Xero,
So basically you can do a brake stand with your boat before letting 'er buck at 40% power! Better launches than starting from an idle like we do now wouldn't it? If you need to maintain position would you have to slip the brake a bit? Any top speed stories?

[Xerophobic]

As far as I know the brake assembly was designed(and is only used) for docking and controlling the turbine output while maneuvering etc. I seriously doubt you would gain anything from the type of hole shot arrangement as you're implying because I think you'd get huge cavitation to throw that much power into a pump instantaneously. The issue with the turbine at the dock is you cannot start and stop the turbine quickly like you can with a piston engine. Once throttle drops below 45% with the brake setup you can instantly start and stop the output shaft completely
Marks T-58 can make 1400 HP altho I know he does not have it dialed up to do so. I believe he was typically running it at about 65% N1 speed and hitting 90's. Again its hard to explain the power output in terms you can compare to a typical engine as the N1 and N2 shafts are not connected(I recall being the typical "turbine ignorant passenger" and asking him this very question and him having a very hard time giving me a straight answer as you cannot think of it as you can with a piston engine)
Picture the N2 shaft being attached to a pinwheel that's rotating due to the exhaust gas flowing through it. Its almost hard to believe but that exact concept is how a free turbine works. That one little rotor (~14" dia) makes 1400 HP just spinning in the exhaust flowing out of the turbine!

Top speed? I'm sure Marks boat could not only be scary but possible exceed the safe limits of the 23' Steptec hull if he chose to run the turbine to the max. (the T-58 weighs just 350 lbs!)
The main disadvantage of the T-58 is the reverse rotation of the output shaft. Mark uses a custom bowl/impeller which spins backwards

Cheers

[sandman]

Does the use of a gear reduction box become neccessary,or does the output turbine speed self govern with the load? Cavitation may be something incredible if your pump gulps some air!

[Xerophobic]

[RPM]

That is very very cool . I hadn't looked at the nye turbine boat for a while until the the unlimited turbine post came up . I looked through their site a little closer, that turbine puts out over out over 1200 lb. ft. torque @ 6000 output shaft rpm. and it weighs 350 lbs . Even if you have to cruise around the circuit you know its going to wail on the power by the half hour marathon legs . A friend of mine has been wired on to getting a small allison for close to ten years when he first saw them with some military surplus. If your out of jet fuel I'm told you can run it on diesel mixed with a little reg. gas mixed in.

[Xerophobic]

the turbine will burn almost anything. In fact you can pretty much mix as you wish it will just not burn pure gasoline as it burns too hot. How about completing your next race using a cheap fuel mix of stove oil and diesel or kerosene
The fuel governer will automatically adjust for the fuel there is no change to engine operation only in some cases startup procedure.
I'd grab one of those little Allisons in heartbeat if I didn't have too many projects on the go now!

Cheers

[RPM]

Xero do you have any fuel flow numbers for Mark's boat at his current top speeds. Curious as to how much you need to pack if you were to let er run hard for a half hour or so ? Kerosene cheaper than C-12 but making power to weight outputs like these turbines do with diesel mixed with reg. would be nice

[Xerophobic]

95gal/hr @ wot

oh wait that's not Marks turbine, that's someone elses

[Xerophobic]

For those who have not figured this out yet(or heard through the rumor mill) my most current project is in fact the U353 boat
(guests can't post on the forum unless the moderator enables that feature for 5 mins or so hehe)

This all dates back to when I had some talks with Howard at Firestorm turbines last year. I had previously met Howard years ago at the Toronto boat show, he even remembered me.
In any case Firestorm does installs in offshore boats mostly while Howard himself services turbines in helicopters for a living. For various reasons talks with him, Mark Nye and others, I settled on the T-53 Turbine from a Huey Chopper. The engine will be a surplus US military engine.

Since then I have tried to tackle solving the technical issues with doing a drive train such as this, drive shaft, exhaust issues etc

I have completed the drawings for the boat and decided on geometry for the hull. One of the challenges was the layout of the T-53. While this engine has a very favorable output rpm and rotation (CW and 6600 rpm max)it is what is referred to as a cold shaft engine meaning the intake and output shaft are on the same end. This means I had to either chose to run the engine "backwards" or run through a gearbox similar to a vdrive. In interests of simplicity, weight and cost I have chosen to run the engine backwards. In this layout the exhaust from the turbine will exit the engine facing the front of the boat. A duct will be fabricated to divert the exhaust up and rearwards. An insulated firewall will be made to separate this from the seating compartment. I felt this was the best compromise to ensure trouble free operation of the engine. Of course the main strength of the engine is reliability and the last thing I wanted to do was add a link to the chain which could be come the weakest link and ruin that reliability. A drive shaft hooked directly to the pump for me is the best solution.
A few pics:

[Xerophobic]

The drawings of the boat as they progressed from engine/pump layout through hull layout and cockpit spacing etc
The hull ended up being a 23 foot tunnel with the deck of a 21 to give a cockpit 2 feet longer than the 21.
The last drawings are of an exhaust duct I output using HVAC software.
A very nice piece of software I cannot fathom anyone operating an HVAC business without. It will out put even this complex shape to 2D flat forms in both CAD format and layouts.
I can't see another way I could have easily made a transition duct that went from 15" round to 10" x 30" rectangular. We felt it was critical that the exhaust section increase as it passed through the transition so as to not restrict flow in the turbine. Something which utterly destroys turbine performance. My duct nearly doubles in cross section from start to end.