Flugwerk AP-51 Palomino for Unlimited?

[spacegrrrl]

Re: Flugwerk AP-51 Palomino for Unlimited?

Spacegrrrl, We, the "Blind Man's Bluff" guys did buy several 3350-26 WD engines at very low price. We only ran ONE to destruction on the dyno at Gary Aerospace in Hondo, Texas, to find the weak points, or whatever, but ran several to make sure they were O.K after being stored for a long time, and also because we had no paperwork on them. These engines had little value at that time, because there were those who were convinced that they would not fit in a Sea Fury cowl. I designed a motormount, and "mocked up" our Sea Fury with one of our engines, complete with a prop hub, and put the Sea Fury cowl on. I sent photos to "interested parties", built several engine mounts, had spinners and backplates made of carbon fiber, and the rest is history.

Larry

Thanks for the clarifications. I was basing my comments on an SAE meeting on Phoenix I attended where someone from the BMB team and Skip Holmes spoke. I kinow at the time the feeling conveyed was the engines in question were easily available and very cheap for what they were. Basically the last pile of stuff left over from Skyradiers and as you said "random canned engines with no paperwork."

I just keep crossing my fingers and hope that the goverment will finally open up the warehouses where they store the Ark of the Covenent and in there we'll get hundreds of these wonderful WWII engines in crates...

I mean, I can dream, right!

Spacegrrrl

[jarrodeu]

Re: Flugwerk AP-51 Palomino for Unlimited?

So what exactly is the weak part on the contra-rotating prop? Could it be fixed? (yeah I know, $)
As planes get faster, are they going to hit a wall with prop efficiency? Wouldn't a contra prop be better at higher speeds than a single prop?

Jarrod

[spacegrrrl]

Re: Flugwerk AP-51 Palomino for Unlimited?

So what exactly is the weak part on the contra-rotating prop? Could it be fixed? (yeah I know, $)
As planes get faster, are they going to hit a wall with prop efficiency? Wouldn't a contra prop be better at higher speeds than a single prop?

Jarrod

I heard repeatedly that they aren't as efficient. But I can't say I've ever seen anything specifically to show that.

Spacegrrrl

[Leo]

Re: Flugwerk AP-51 Palomino for Unlimited?

[QUOTE]Different airplane. [QUOTE]

Thanks! I didn't get an N number off of it to verify, assumed with the same basic paint and the article waaaaaay back about it's re-engining (is that a word) it was the same.
Wouldn't the shackleton prop setup for the Griffon be optimized for cruise and not speed?

[Big_Jim]

Re: Flugwerk AP-51 Palomino for Unlimited?

So what exactly is the weak part on the contra-rotating prop? Could it be fixed? (yeah I know, $)
As planes get faster, are they going to hit a wall with prop efficiency? Wouldn\'t a contra prop be better at higher speeds than a single prop?

Jarrod

The unit itself (as utilized by the three Griffon racers) is definitely not as efficient for a racing environment. Remember, the Shackelton/Griffon setup was designed for long-distance, overwater patrol flights where you loiter for hours and hours and hours.

I am no expert in the prop-efficiency department, but just on observation there has to be some sort of \'dirty\' air coming off the front blade for the second blade to try to get a bite out of. I\'m sure there is some benefit from it, otherwise Supermarine wouldn\'t have done the Seafires and some of the late-model Spitfires with similar units.

Now, if it were a constricting, shrouded set of blades where the air is being compressed by the first into the second set (think inside a turbine engine compressor section, or a ducted-fan), you might be able to get some sort of efficiency gain.

Again, I\'ll point to the fact that the RB modification was 35 years ago, and they were \'trying something different\' with what they could get ahold of. The benefit they thought they could get out of the counter-rotating props was that it eliminated P-factor and torque at a small sacrifice of horsepower/efficiency. They were willing to make that trade-off because they had extra cubic inches to play with. Note that when Z was looking into the Griffon on Jeannie and Stiletto, he went with a Rotol 5-blade unit instead of the Shackelton unit.

Why did Whittington put it on his bird? Because he got tired of being beat by the RB...it\'s just that the game changed while he was away at camp, and by then the technology had passed it by. My impression was that on MAII it looked cool and that was just what Mr. Rogers wanted to do, not necessarily because it was the best route to go.

[jarrodeu]

Re: Flugwerk AP-51 Palomino for Unlimited?

I'm probably going to sound like an idiot here. Since the 5 blade spitfire props are so rare, are there other props, possibly commercial designs that can be modified and used? Maybe something from a turboprop? Maybe make a new hub?

Jarrod

[AAFO_WSagar]

Re: Flugwerk AP-51 Palomino for Unlimited?

My impression was that on MAII it looked cool and that was just what Mr. Rogers wanted to do, not necessarily because it was the best route to go.

Bill told me at the time, that they would love to have gone away from the contra-prop setup but it was all about the $$ and time. I suspect, eventually, they would have found both and would have made the changes.

[Big_Jim]

Re: Flugwerk AP-51 Palomino for Unlimited?

So what exactly is the weak part on the contra-rotating prop? Could it be fixed? (yeah I know, $)
As planes get faster, are they going to hit a wall with prop efficiency? Wouldn\\\'t a contra prop be better at higher speeds than a single prop?

Jarrod

As for the \\\'weak point\\\', my opinion is based off my discussions with Jeff Neff who built the ex-Budwieser motors for Whittington. The RPM that they were capable of running when they were in the hydroplane was 4200 at 140 inches of manifold pressure...but that was with a fixed-pitch, three blade prop about 15 inches in diameter that was in and out of the water, not an 11-foot twin-variable-pitch aircraft prop.

With a variable-pitch airplane prop, the faster the engine turns (RPM) the more blade angle (i.e. bigger bite of air) the blade needs to hold to keep the engine from overspeeding. The prop governor uses an oil-driven piston to hold the selected blade angle, and the oil pressure needs to be maintained in order to prevent centripetal force from pushing the blades flat.

When they tried to put the 140/4200 to the test during Sunday\\\'s race on Precious Metal, the prop governor couldn\\\'t hold all six blades at such a huge blade angle and failed. So just like with the RB (which I believe lost oil pressure due to a failing engine...but pressure lost is pressure lost regardless of \\\'why\\\'), all six blades immediately went to flat.

When we were flying the P-3, the prop system was designed with a set of \\\'pitchlock\\\' teeth to prevent such a failure. The oil pressure actually held a pair or ratcheted-teeth disks apart, and if pressure was lost, the disks came together and manually \\\'locked\\\' the blade at whatever angle was present when the failure occurred.

I also understand that when MAII was built, there was a separate pressurized \\\'emergency tank\\\' that in the event of a failure of this type provided a \\\'one-shot deal\\\' to feather the props to prevent the RB/Precious Metal type of failure.

But again, I point to what I said in my previous post about the Shackelton unit being designed for cruise/loiter where you\\\'re not pulling a lot of manifold pressure or rpm and you just don\\\'t have the same kind of \\\'load\\\' on the system that you would in a racing environment. It\\\'s not inherently a \\\"weak point\\\" as you suggest...because used in the environment it was designed for, it works very well.

[jarrodeu]

Re: Flugwerk AP-51 Palomino for Unlimited?

Thanks, that is a great explanation. Even I can understand it!

Jarrod

[Big_Jim]

Re: Flugwerk AP-51 Palomino for Unlimited?

Thanks, that is a great explanation. Even I can understand it!

Jarrod

A motor guy could probably clean the explanation up a bit and correct any discrepencies, but that is the basic way it works.

[kiwiracefan]

Re: Flugwerk AP-51 Palomino for Unlimited?

Big Jim...
thanks for the explanation on how things in the contra-props worked..
Re-Reading my copy of racing griffon mustangs it was mentioned that the RB team cut the back props down by about 3 inches. i do recall that the 46/47 seafires only used the contra props for easier use off the small english carrier decks as the fore mentioned P-factor reduction.
The other thing to remember is that the firefly used a big 4 blade prop with its griffon

[Big_Jim]

Re: Flugwerk AP-51 Palomino for Unlimited?

Re-Reading my copy of racing griffon mustangs it was mentioned that the RB team cut the back props down by about 3 inches.

Yup, all three teams used a cut-down prop. I have pictures from August of 1988 taken down at World Jet right after they put the prop onto Precious Metal....it's a full-length, eliptical tip prop and it really looks out of place. And as I recall, when they clipped it the rear prop was a little smaller than the front one.

[spacegrrrl]

Re: Flugwerk AP-51 Palomino for Unlimited?

Bill told me at the time, that they would love to have gone away from the contra-prop setup but it was all about the $$ and time. I suspect, eventually, they would have found both and would have made the changes.

Bill told me exactly the same thing. It all came down to a huge difference in cost. If he could have found one that fit in the budget he would definitely have gone with the 5 blade.

Spacegrrrl

[Randy Haskin]

Re: Flugwerk AP-51 Palomino for Unlimited?

Fat the peak of "proper" unlimited hydorplane racing the Circus Circus team was said to have over 70 Griffons sitting around somewhere.

When did Circus Circus run Griffons?

[Lockheed Bob]

Re: Flugwerk AP-51 Palomino for Unlimited?

I think Bill "Tiger" use to have some Griffons outside his hanger. Don't know whatever happened to them.