good idea??

[stuntflyr]

Re: good idea??

Are you using the full G6 with the aux stage blower? As I recall, they were rated at 3200 and 100". Gonna have to use a short prop on that engine reduction gear set up. I would say that a complete G6 package would be relatively hard to come buy and I don't know that it would really be any easier to maintain. Just my .25c

Sparrow

Hi,

I have some questions.

Does the fluid drive for the aux blower have a torque reduction effect on the total power output to the prop reduction like high blower seems to on a Merlin? Would it be less? Is it worth the hassle?

Without an aux blower do the gear selections for the Allison's blower include enough selections to get as high a manifold pressure as a Merlin?
Can an Allison blower make the same MP at the same blower speed as a Merlin? If not, why? Diameter? Vane design?

You mentioned using a small diameter prop for the G6, is it not slow enough for a Reno set-up? Are there reduction gear selections that are slower? Does anyone use slower than 420's on Merlin's anymore? Are there any factory gear selections slower than that for Merlin's or were the 390's only a Z thing?

If you were gonna use an Allison, say because you had 10 in crates and they were in good shape, what would you do to make hp at 5000 feet, and what would be a reasonable hp rating for which to hope?

Thanks,
Chris...

[Sparrow]

Re: good idea??

Does the fluid drive for the aux blower have a torque reduction effect on the total power output to the prop reduction like high blower seems to on a Merlin? Would it be less? Is it worth the hassle?

I would assume that it does to a certain degree as it can consume up to 345 HP to drive the aux stage. The fluid coupling is not directly controllable buy the pilot to be able to increase/decrease boost. There was a complete fuel operating system with a speed density carburetor that pretty much controlled all the operating parameter's of the engine, including the controlling of "overboost" situations.

Without an aux blower do the gear selections for the Allison's blower include enough selections to get as high a manifold pressure as a Merlin?
Can an Allison blower make the same MP at the same blower speed as a Merlin? If not, why? Diameter? Vane design?

No on both counts. The reason an Allison can't make the boost is it has a single stage, single speed supercharger.

You mentioned using a small diameter prop for the G6, is it not slow enough for a Reno set-up? Are there reduction gear selections that are slower? Does anyone use slower than 420's on Merlin's anymore? Are there any factory gear selections slower than that for Merlin's or were the 390's only a Z thing?

I was mistaken on that after doing some research. The true "G6" Allison had a reduction gear ration of 2.36/1 or basically .424 which is for all intents the same as the Rolls .420. As far as I can see, unless custom gearing was made, that is the only gear selection for the G6's. As far as .383 or the .361 gears that were tried on Merlin's, no they are no longer used. The tooth contact of the pinion gear to the prop shaft gear is such that they will not take the pressure of the gear loading and they will shell the teeth off the pinion. Those gear ratio's were utilized when the theory of high HP was related to high RPM. Since the advent of the "Mouse Motor" (right Wayne??) that theory has been reversed and the .420 gear set is pretty much the standard. One may be able to make a gear set in the .400 range that would live and possibly be just as advantageous. But, in doing that other changes would have to be made elsewhere to take full advantage of the slower reduction gear ratio. Other's besides Zuechel used custom reduction gear ratio's. A .383 gear set has been used on a racer within the last 10 years, as I said earlier it suffered a gear tooth failure.

If you were gonna use an Allison, say because you had 10 in crates and they were in good shape, what would you do to make hp at 5000 feet, and what would be a reasonable hp rating for which to hope?

In all honesty? I would trade them for a Merlin with a 2 stage blower. According to Dan Whitney's V's for Victory book, a G6 Allison was capable of 2250 HP up to 30K alt. To go through all the mods and development processes that would be required to make an extremely high HP Allison would, to a certain degree, be re-inventing the wheel. The -111 Allison I built for the "A" model of Jerry Gabe's ran around at Reno with a max power of 3000 turns and 49" MAP WFO. Single stage blower folks! Way back when, a fellow involved in boat racing was trying to graft a merlin wheelcase and blower to an Allison, it was never completed and of course was probably an engineering nightmare. The Allison crankcase because of it's construction is stronger, but to get the HP is much more involved in my opinion, than it is to get from a Merlin. A Merlin is much more readily adaptable to "hot rodding" than the Allison is.

Sparrow

[stuntflyr]

Re: good idea??

Thanks for the info.
I guess I don't really understand the "two speed, two stage " supercharger as it relates to racing at Reno. I was under the impression that the engine is operated in low blower, and the "tube" type engine is utilized.
Does this engine set-up still have some sort of two speed wheel?
Is the engine run in high blower?
Thanks,
Chris...

[51fixer]

Re: good idea??

Chris wrote:
I guess I don't really understand the "two speed, two stage " supercharger as it relates to racing at Reno. I was under the impression that the engine is operated in low blower, and the "tube" type engine is utilized.
Does this engine set-up still have some sort of two speed wheel?
Is the engine run in high blower?

Chris,
The two stage blower means there are 2 compressor impeller wheels thus two stage and there is the ability to change the speed the wheels turn at thus two speed.
The Allison has a single compressor impeller wheel and runs at a single speed. There were a couple different gearing set ups for setting a speed that it runs at in the earlier models of the Allison. An engine used in a P-38 ran the supercharger at a slower speed because of the use of an external turbo. Other models w/out the turbo ran at a higher speed.
The G6 was set up different with the blower and the fluid drive.
Sparrow can talk about the tube, but I believe it just replaces the aftercooler as ADI is used to cool the induction charge. The blower is still a 2 stage unit.
He won't let us have a tube on our engines.
Rich P.

[speeddemon]

Re: good idea??

Well, here's the scoop, as I can best describe.

--The Allison was chosen for its simplicity and availability (i.e. Murdo HAS them). The theory behind this is the "Tsunami-prinicple". Most people don't remember that in its original concept, Tsunami was supposed to be powered by an Allison. Then it was upped to a single stage Merlin. Then finally to the two-stage. But the thought is the same...the airframe is going to be very close to the 4500 lb rule...that is a good 3000 lbs lighter than Strega/Dago/etc. The hope is that the horsepower to weight ratio, even WITH the Allison, will be equivellant or better to the current racers.

--The team has the canopy mold that was used on World Jet/Precious Metal, and the plan is to use it, however to modify the entry-egress method to what the current Grand-51 has (i.e. a hinged canopy a'la Miss Merced).

--The current molds can be easily modified for clipped wings, and the decision has been made to have the upswept tips that are prevalent in the Unlimiteds at the moment. And as somebody pointed out, with a composite kit, the wing and fuselage will be clean and smooth right out of the mold--no "Kerch treatment" needed. It will be one VERY slick airframe. The wing is actually patterned after a P-51G wing/airfoil. Murdo felt that this was the optimal wing that North American/NACA designed.

--If things go as planned, Murdo wants to be the race pilot. He is a retired airline pilot, with a lot of high performance time in a similar airframe.

Will it work? I dunno. But I do know that when Skip Holm took a test flight in the turbine-powered Grand-51, he was VERY impressed with its handling capabilities and its speed. Told Murdo he had a real hot-rod on his hands. I think that was the thing that tipped the scale for Murdo to go for a racer version. Either way, I know Murdo is very serious about it, the funding is there, the parts are there, and nobody is in a hurry--so its trying to be done right. Should be fun to see how it all goes.

[speeddemon]

Re: good idea??

Way back when, a fellow involved in boat racing was trying to graft a merlin wheelcase and blower to an Allison, it was never completed and of course was probably an engineering nightmare.

Mike, are you referring to Roy Duby's experimental "Dubenhauser" engine? I'm pretty sure that is exactly what Roy did for the Gale/Miss Smirnoff team in about 1964-65. You are correct that it was a nightmare--hell, the thing LOOKED like Frankenstein's Monster--but I know they pulled some pretty good horsepower out of it when it did run.

Obviously, airplanes and hydroplanes are two completely different entities to compare...but the teams that have successfully run the Aux-Stage Allison (mainly Bill Waggoner's "Maverick" driven by Bill Stead), the G-6 was equal or better to ANY of the Merlin-powered boats of the day, including the Bardahl and Thriftway teams.

Of course, most of those were still relatively 'stock'.

So here's another question for you, Sparrow: What do you know about the Allisons that Z built up for Jack Sandberg in the '70's? I also seem to recall that he built up an alcohol-powered Allison for Mike Carroll to use in the ill-fated Cobra III. Obviously, it was never installed and used. But what do you think were done to those Allisons, and how would their power output compare to what could be done to them today?

[440_Magnum]

Re: good idea??

The Allison crankcase because of it's construction is stronger, but to get the HP is much more involved in my opinion, than it is to get from a Merlin. A Merlin is much more readily adaptable to "hot rodding" than the Allison is.

Sparrow

Hi Sparrow. I've always wondered something about this and never have found a firm answer.

Are ALL the reasons that the Merlin is "more adaptable to hot-rodding" than an Allison related to the limited boost that one can get with its single-stage blower? Or are there other reasons as well (mechanical weak points, intake/exhaust flow limitations, etc.)? From what I've been able to gather, the Allison seems to have some purely mechanical (strength) advantages in almost all areas. Stronger rods, stronger crankcase, simpler gearcases and power take-offs. So if there were some way (hypothetically) to feed it the same kind of manifold pressure that you can achieve on a Merlin, how do you think it would fare? In wartime applications, turbocharging was used to overcome the lack of a technologically advanced blower(*) on the Allison, not so much for big power but for altitude compensation. Why no turbo Allison racers nowdays?

(*)- As evidence of just how much better the Merlin blower is- I seem to remember that the design of the 2-stage 2-speed Merlin blower involved "Doc" Hooker, who was later a key to the success of first the Bristol turboprops and turbojets, and was later brought out of retirement to "save" the Rolls RB.211 for the TriStar when it looked like it was going to take down both Rolls and Lockheed. Hooker was a genius at designing turbo machinery.

[stuntflyr]

Re: good idea??

Chris wrote:
I guess I don't really understand the "two speed, two stage " supercharger as it relates to racing at Reno. I was under the impression that the engine is operated in low blower, and the "tube" type engine is utilized.
Does this engine set-up still have some sort of two speed wheel?
Is the engine run in high blower?

Chris,
The two stage blower means there are 2 compressor impeller wheels thus two stage and there is the ability to change the speed the wheels turn at thus two speed.
The Allison has a single compressor impeller wheel and runs at a single speed. There were a couple different gearing set ups for setting a speed that it runs at in the earlier models of the Allison. An engine used in a P-38 ran the supercharger at a slower speed because of the use of an external turbo. Other models w/out the turbo ran at a higher speed.
The G6 was set up different with the blower and the fluid drive.
Sparrow can talk about the tube, but I believe it just replaces the aftercooler as ADI is used to cool the induction charge. The blower is still a 2 stage unit.
He won't let us have a tube on our engines.
Rich P.

Thanks Rich,
I have not really appreciated the difference between the Merlin and the rest of the supercharged engines in use. Thanks for the information. I'm not familiar with your name so your reference to "ours" I assume is that Sparrow built a Merlin for a Mustang you own or crew? Sounds fun, thanks again.
Chris...

[stuntflyr]

Re: good idea??

Sparrow,
Thanks for all of the info and your time in answering. I guess I didn't fully appreciate the difference in the Merlin's supercharger compared to essentially all the rest. Most of my experience is with radial engines and they all, I assume , have single stage blowers.

Interestingly, I recall Larry Havens telling me he was making 85 inches at 3400 rpm with his Allison. I was so young I don't recall at what altitude or DA as we were at Long Beach. He could've been at low altitude. At two inches per thousand that would drop the Reno MP to 75 inches if it was making 85 at SL. Would the Gabe engine make that sort of MP at 3400?

Another interesting note, Charlie Tucker ran a stock P-63C engine (equipped with the aux blower and all) with water and was able to propel that clipped wing King Cobra to 393 mph timed avg over two laps for qualifying in the '46 Thompson. That is 25 mph faster than any time Havens ever made with his, and a full 50 mph faster than Sandberg ever did with his. Any ideas why?

Chris...

[speeddemon]

Re: good idea??

Sparrow,
Another interesting note, Charlie Tucker ran a stock P-63C engine (equipped with the aux blower and all) with water and was able to propel that clipped wing King Cobra to 393 mph timed avg over two laps for qualifying in the '46 Thompson. That is 25 mph faster than any time Havens ever made with his, and a full 50 mph faster than Sandberg ever did with his. Any ideas why?

Just something to keep in mind, it is kind of unfair to compare the speeds in the Thompson versus the speeds at Reno. Reno has a nine mile (and shrinking) course that is mostly turns. The Thompson had (three out of four years) a parallelogram-shaped course that was BIG--something like 30 miles. That is a LOT of time to get straight line speed, and increase your average. I'll bet that on the same course, Crazy Horse or Tipsy Miss could have turned in some pretty good speeds too.

Also interesting to keep in mind--Larry Havens' plane was actually Charlie Tucker's "Easter Egg"...not the one with the HUGE wing clip, but the other one with the less severe clip.

[Sparrow]

Re: good idea??

Speeddemon:

I wasn't aware of that one. I was told about the one that Gillam was trying to create and never got done. That thing had to be a contraption. You got any pictures of it??

Sparrow

[speeddemon]

Re: good idea??

Speeddemon:

I wasn't aware of that one. I was told about the one that Gillam was trying to create and never got done. That thing had to be a contraption. You got any pictures of it??

Sparrow

Actually, yes...I think I do have a picture of it somewhere. I'll see if I can find it and post it in the next couple days.

Never heard of what Bob Gilliam's project was. That surprises me...he was right around here, and nothing he ever did was really whole-hearted. He'd start something and then lose interest...and then show up at the race with a 'run what you brung' attitude. That's why he never really did very well. But he certainly was a personality.

[speeddemon]

Re: good idea??

Speeddemon:

I wasn't aware of that one. I was told about the one that Gillam was trying to create and never got done. That thing had to be a contraption. You got any pictures of it??

Sparrow

This is the best I could come up with...it is copyrighted by Jim Dunn, but the series of cards were given over to the domain of the Hydroplane Museum as part of their data base. I think it is pretty good. Here is what the back says:


"The two most widely used engines in Unlimited racing after World War II were the Allison and the Rolls Royce Merlin. The Merlin, with its two stage supercharger and aftercooler produced more horsepower. The Allison, stronger and less complex, was more dependable. Roy Duby engineered a hybrid using the best parts of each engine. The "Dubinhauser" consisted of a Merlin induction system (wheelcase & supercharger) mounted on an Allison crankcase and cylinder block. Duby began the experiment while crew chief and driver for George Simon. He tested it first in Miss U.S. 1 at Lake Eloise, Florida. After the 1965 season, Duby moved to the Gale/Smirnoff team. Lee Schoenith had him build 10 Dubinhausers over the winter. The engine ran in competition only once: Duby drove Smirnoff at the '66 San Diego race, won the final heat, and placed fourth overall. Duby's concept showed potential, but was too costly. Schoenith discontinued it and gave everything to Graham Heath when the Gale team switched from Allison to Merlin."

[stuntflyr]

Re: good idea??

Just something to keep in mind, it is kind of unfair to compare the speeds in the Thompson versus the speeds at Reno. Reno has a nine mile (and shrinking) course that is mostly turns. The Thompson had (three out of four years) a parallelogram-shaped course that was BIG--something like 30 miles. That is a LOT of time to get straight line speed, and increase your average. I'll bet that on the same course, Crazy Horse or Tipsy Miss could have turned in some pretty good speeds too.

Also interesting to keep in mind--Larry Havens' plane was actually Charlie Tucker's "Easter Egg"...not the one with the HUGE wing clip, but the other one with the less severe clip.

Hi Speed,
I know, but...the Thompson course was reduced from 30 to 15 miles from 47 on. The turns would account for some of the speed differential, but...

I thought the DA difference would boost the speed at Reno more than the loss of manifold pressure would create a speed loss. In looking at the speeds put up by Larry Havens in N9009 (the ex NX63231), when the engine was running with the water working, it went about 375-380 on the 1971 course, which was 9.8 miles. (I also remember that when the 270 degree induction duct was at speed it made less MP per mph at some point. Later talk was to reinstall the regular dorsal scoop for decent ram rise at speed.)

In 1949, Charlie Tucker qualified the "Easter Egg" NX63231 at 393 mph on the 15 mile course at Cleveland. This time the aux blower had been removed, and it went well obviously.

Perhaps Larry's 1971 version could've gone faster than Chuck's 1949 version if the ram rise problem hadn't cost the '71 version a bunch of MP? Who Knows?

I miss those Bell racers. Tipsy Miss was never in a condition to actually race, it seemed. Mr. Mennen was another tragic Reno faux pas victim. As a little boy, I remember driving past the Long Beach Airport on the 405 seeing the Pylon Air hangar and all of the Bell stuff going on. Mike Carroll's Cobra, Larry's King Cobra, and all of those fuselages and wings from a few different Cleveland King Cobra's out in the back lot along the cyclone fence. Cool stuff, but mom and dad wouldn't usually stop.
At least I got to see them.
But if luck and timing had been different and they all had been there at the race at once, would'nt that have been grand!

Chris...

[speeddemon]

Re: good idea??

Hi Speed,
I know, but...the Thompson course was reduced from 30 to 15 miles from 47 on. The turns would account for some of the speed differential, but...

I thought the DA difference would boost the speed at Reno more than the loss of manifold pressure would create a speed loss. In looking at the speeds put up by Larry Havens in N9009 (the ex NX63231), when the engine was running with the water working, it went about 375-380 on the 1971 course, which was 9.8 miles. (I also remember that when the 270 degree induction duct was at speed it made less MP per mph at some point. Later talk was to reinstall the regular dorsal scoop for decent ram rise at speed.)

In 1949, Charlie Tucker qualified the "Easter Egg" NX63231 at 393 mph on the 15 mile course at Cleveland. This time the aux blower had been removed, and it went well obviously.

Perhaps Larry's 1971 version could've gone faster than Chuck's 1949 version if the ram rise problem hadn't cost the '71 version a bunch of MP? Who Knows?

I miss those Bell racers. Tipsy Miss was never in a condition to actually race, it seemed. Mr. Mennen was another tragic Reno faux pas victim. As a little boy, I remember driving past the Long Beach Airport on the 405 seeing the Pylon Air hangar and all of the Bell stuff going on. Mike Carroll's Cobra, Larry's King Cobra, and all of those fuselages and wings from a few different Cleveland King Cobra's out in the back lot along the cyclone fence. Cool stuff, but mom and dad wouldn't usually stop.
At least I got to see them.
But if luck and timing had been different and they all had been there at the race at once, would'nt that have been grand!

Chris...

They didn't actually change the Cleveland course until 1949, I think. But thats just splitting hairs.

I don't remember much first hand about Crazy Horse, because I was very young...but within the last 10 years or so I have talked with Larry about the plane. He admitted that in '71, the plane was nowhere near 'race' condition, that it was still in the testing phase, and that he was still getting used to flying it. He did feel that in '72, the mods that he had made would have made it better...but that he also had purchased a Merlin and was considering modifying the airframe to run off THAT.