Question for the engine guys: Merlin/Griffon Boost Engine??

[Sparrow]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

In regards to both the Merlin and the Griffon when boat raced, they didn't have the advantage of the ram air as the airplanes do. Merlins were turned up to 4500+ RPM and struggled to get much past 125" MAP. The Griffon had the same disadvantage, however one thing that really woke up that engine was the installation of a PR-100 carburetor. It was discovered that both the original metering body and a PR-58 were both acting as chokes on the top end. Griffons also ran in the 4500 range of RPM, boat racing. As said above, the ram pressure across the supercharger is multipled which increases the boost dramatically in flight conditions. The Griffons in the boats, in conjunction with the PR-100 carbs also used Nitrous-- lots of it. Bernie Little of the Budweiser Racing teams also had a lot of custom blower drive parts made. The blower drives are one of the weak areas of the Griffon and liked to break.

If your interested in seeing what a Mustang did at 80" (+25), study the documentation pertaining to a P-51H Mustang as they were flight tested in those ranges. As far as a Griffon in a Mustang, study up on the history of Precious Metal. The other factor with the Griffon in a Mustang is the HP to weight factor, the Griffon being a fair amount heavier than the Merlin.

[J.A.W.]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

Those P-51Hs could run up to 90in with ADI..

[Big_Jim]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

That was my thought, does the 'boost' drive have to be reciprocating?

Snidely

Chuck Lyford toyed with the idea of installing a Garrett turbine engine to run the supercharger on the Bardahl Special. It would have necessitated moving the cockpit back a few feet (farther back than even Stiletto did). Never got past the drawing stage. But the rules at the time didn't say you couldn't power the accessory/supercharger with anything in particular...it just said the plane had to be piston-powered...which it still would have been.

[ChrisMX105]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

Never thought of a Turbine, could probably use a wastegate to keep the boost consistent with engine requirements. Anyone have a cool 100 million to develop the concept?

[Big_Jim]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

Never thought of a Turbine, could probably use a wastegate to keep the boost consistent with engine requirements. Anyone have a cool 100 million to develop the concept?

This was several years ago when we talked about it, but I think that was kind of the idea...that the turbine would run at 100% all the time and a wastegate would dump off the excess of what the Merlin needed at the time.

[ChrisMX105]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

This was several years ago when we talked about it, but I think that was kind of the idea...that the turbine would run at 100% all the time and a wastegate would dump off the excess of what the Merlin needed at the time.

I still wonder how the Merlin would run without the power draw of the supercharger. I would think that without the load on the crank that things may twist up differently and break.....

Engine Guru input please.............

[N22252]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

I still wonder how the Merlin would run without the power draw of the supercharger. I would think that without the load on the crank that things may twist up differently and break.....

Engine Guru input please.............

How does the RR Meteor tank engine behave in this regard? I had always heard the meteor was essentially a Merlin stripped of its supercharger?

[ChrisMX105]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

How does the RR Meteor tank engine behave in this regard? I had always heard the meteor was essentially a Merlin stripped of its supercharger?

I would think that the loads would be way different, A de-rated Merlin with no boost wouldn't have nearly the stresses a wound up race motor running 80-90 inches would have.

When I hit the SuperPowerGigabucks Jackpot it will be known.................

[Snidely]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

Never thought of a Turbine, could probably use a wastegate to keep the boost consistent with engine requirements. Anyone have a cool 100 million to develop the concept?

Just to put some numbers out there,

Pratt & Whitney PT6B(helicopter) has a transmission output right around 1000hp. This is at 4600 rpm.
weight: 370 lbs w/ no fuel/oil/connections/mounting/hardware/etc.
fuel: 0.581 lbs/shph 1000hp = 581 lbs/hr. = 1.34 gallons per minute. (please check my math)
(source:http://en.wikipedia.org/wiki/Pratt_%...ney_Canada_PT6)

Any 'outside' boost capability will have exhaust, right? Which direction should it go, Aft, right?
This would require a whole new look at inter-cooling.

Snidely

[J.A.W.]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

Yeah, Snidely, that's the thing..

& maybe the turbine efflux utilized in a 'Meredith' duct-type 'blown' coolant heat extractor system?

Would that be legal?

[Snidely]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

Liquid Nitrogen boil-off intercooling, with un-obtainium light weight tanks.

Snidely

[J.A.W.]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

As the oft-quoted aero-space flight engineer was wont to say..

"Och, ye cannae change the laws o' physics Capt'n! "

[MIKE NIXON]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

There have been a number of cars and other things(?) that have used the Merlin for power. The tank engine is just one of many applications.
re twist of the crank:
when you run the numbers on the amount of power a merlin generates to get 3,000 HP to the prop, the crank is absorbing close to 5,000 HP.
One of the tests we do on Strega's crank every summer is to check for any twist from the front to the rear crankpin. It is still the same crank since '07 with no change.
On a side note, when the Merlin is run without the supercharger the engine uses a lot of oil at low power. The low boost (high vaccume to us old car guys) sucks in a lot of oil. We fixed a car Merlin for a customer by using automotive engine clearences on the valve guides. It wouldn't pass smog test!

[J.A.W.]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

That's funny, I have just done the valve guide seals..
.. on my classic M-B 3.0 inline 6 DOHC 24-valve Coupe-

- for exactly that reason..

So, maybe slotting in a couple of compact turbos will save me the hassle, eh?

[Gibbs]

Re: Question for the engine guys: Merlin/Griffon Boost Engine??

Well lets start with the Griffon. Due to its bore and overall rotating mass, it peaks out early. It would take a third spark plug in the center of the head to get a big increase in HP. The time it takes to light and burn the charge is the issue here. Yes you can increase the boost and try to balance the timing and octane. Nitrous works also but the net HP to the prop (which is bigger) just never equals the Merlin....

Could be a Griffon generate more aircraft speed by converting the heavier (and surely some HP absorbing) contra-rotating prop with a single 4- or maybe 5-blade prop?

Thx
Gibbs