MA-II Speed Potential

[speeddemon]

Re: MA-II Speed Potential

All of the Griffon birds sound essentially alike. What you hear is the sound of the propellers...and that essentially drowns out the sound of the engine, which you don't hear until after the plane goes past.

But in comparison, the Griffon has a much deeper sound to it...and it sounds like it's loafing as its going away....even though when its coming towards you, you swear it's on the verge of grenading because it sounds like its wound up to the moon. But it's deceiving, because its just the prop noise.

[Peashooter]

Re: MA-II Speed Potential

Jason S. has posted some great Precious vids here:

http://www.warbirdaeropress.com/smf/index.php?topic=621.0

[First time Juke]

Re: MA-II Speed Potential

One thing about MA II I don't understand. If contraprops make the torque lesser, how come the rudder is much bigger than in a "normal" Mustang ?

[speeddemon]

Re: MA-II Speed Potential

One thing about MA II I don't understand. If contraprops make the torque lesser, how come the rudder is much bigger than in a "normal" Mustang ?

One thing that was common amongst all three of the Griffon racers was that the counter rotating props had a tendency to make the planes 'hunt' or 'dutch-roll' when they had the normal size tail. Both the Red Baron and Precious Metal tried to run with the 'small' tails, and they had lots of longitudinal stability problems.

The reason that MAII had the H-tail wasn't the size of the rudder, rather it was the height of the stabilizer, getting it up into the clean airstream.

[First time Juke]

Re: MA-II Speed Potential

The reason that MAII had the H-tail wasn't the size of the rudder, rather it was the height of the stabilizer, getting it up into the clean airstream.

Split tail in a Mustang looks funny, but was it even considered ? Swiss had a WW II single engine fighter with such a tail !

[440_Magnum]

Re: MA-II Speed Potential

All of the Griffon birds sound essentially alike. What you hear is the sound of the propellers...and that essentially drowns out the sound of the engine, which you don't hear until after the plane goes past.

I agree- its very hard to separate the sound of the mixmaster prop from the sound of the engine to do a fair comparison between the Griffon and Merlin. They're both V12s, but they do have a different firing order and the Griffon is significantly bigger. The firing order difference has less of an effect than you might think, though. From one side of the aircraft, both of them essentially sound like an inline-6 (so does an Allison in a P-39 for that matter) because you're hearing half the engine about 10 times louder than the other half. Unlike an automotive v8, V12s fire at even intervals on each of their two banks regardless of which overall firing order is used, so there's no "burble" on either bank like there is with a "square" crank v8 that is used in most cars. If you hear a Merlin or Griffon from directly aft, it does sound like a v12 because that's about the only time you can hear both banks together without the prop drowning it all out. When they're flying, that means that the only time you hear a fairly pure V12 note is also the time that you hear the maximum doppler shift *down* frequency because the plane is moving away from you, so they sound like they're running slower than they really are.

To my ear, the v12 installation that consistently sounds like a v12 is the P-38, since its got a fully plumbed exhaust system instead of stacks. But its also very muffled compared to the installations that use short stacks, so the V12 note doesn't beat you over the head. Its more of an undertone.

[King]

Re: MA-II Speed Potential

If you hear a Merlin or Griffon from directly aft, it does sound like a v12 because that's about the only time you can hear both banks together without the prop drowning it all out.

'Cept standing behind the monster when its running is a little hard for me at 140 lbs. She makes big winds but sounds good!

[Leo]

Re: MA-II Speed Potential

Sounds like a girl I once knew...
The Griffon mustangs have to have the most wicked sound of any of the racers.
When PM and Dago went over us a couple years ago PM just plain drowned out Dago!

[SpinB]

Re: MA-II Speed Potential

With all the Avro Shackeltons the Brits kicked to the curb, you'd think there would be a surplus of Griffons and contra-prop gear boxes. Where'd
they all go?

[jarrodeu]

Re: MA-II Speed Potential

One thing that was common amongst all three of the Griffon racers was that the counter rotating props had a tendency to make the planes 'hunt' or 'dutch-roll' when they had the normal size tail. Both the Red Baron and Precious Metal tried to run with the 'small' tails, and they had lots of longitudinal stability problems.

The reason that MAII had the H-tail wasn't the size of the rudder, rather it was the height of the stabilizer, getting it up into the clean airstream.

Wouldn't "hunt' or 'dutch-roll" cause a lot of drag?

Jarrod

[Peashooter]

Re: MA-II Speed Potential

One thing about MA II I don't understand. If contraprops make the torque lesser, how come the rudder is much bigger than in a "normal" Mustang ?

Blue Foam can explain this better than I, but there is such a thing as the aerodynamic center. When you put more airframe or prop ahead of it, you have to balance it out with more tail area behind it. The best story about such imbalance is in Chuck Yeager's book, "Yeager, An Autobiography", where he recounts the story of trying to get to Mach 2.5 (?) in the Bell X-2. Imagine an airplane swapping ends at that speed because the tail is too small.

The increased prop (disc) area of the Dowty contraprop on the Griff-powered Mustangs requires the larger tail volume.

[MustangFan]

Re: MA-II Speed Potential

And singing! What a SOUND!

You ain't kiddin. Check out this link (warning, this is a large video file - 5MB+):

https://www.airraceaddict.com/R982.wmv

I must have watched that vid a couple of dozen times now, and a still get goosebumps when I hear MAII..she was certainly unique.

[MRussell]

Re: MA-II Speed Potential

You ain't kiddin. Check out this link (warning, this is a large video file - 5MB+):

https://www.airraceaddict.com/R982.wmv

I must have watched that vid a couple of dozen times now, and a still get goosebumps when I hear MAII..she was certainly unique.

THANKS!!! That was the point I was trying to make. I stood (ahem) very near Precious Metal at speed this year, and while she sounds *unique* as well, she doesn't sound like MA2!!

Awesome clip, btw. Who is Dago racing there? I can't make it out.

[MustangFan]

Re: MA-II Speed Potential

Awesome clip, btw. Who is Dago racing there? I can't make it out.

I believe it's Voodoo. Before the current wild paintjob, I think she used to be mostly (if not all) white.

I like watching vids from the "old" unlimited course configuration..seems like the big boys spent more time wings level (or nearly) in the VOS..

[garydpolansky]

Re: MA-II Speed Potential

I agree with MRussell that MAII had a very unique sound. To me she sounded like a cross between a shriek and a howl. I occasionally play my recordings of her going by the stands with the volume turned up. WOW!....... Gary