Differences Strega - Voodoo

[Gibbs]

Sorry for maybe this already was topic, but from what I understand (and this means the other side of the ocean :

is it correct to saying both aircraft have:
- identical aero mods
- identical cooling systems
- nearly identical max. power output

so decisive is daily situation of aircraft and pilot and mainly qualification and race tactics?

thx
Gibbs

[GeeBeeZ1931]

Re: Differences Strega - Voodoo

Sorry for maybe this already was topic, but from what I understand (and this means the other side of the ocean :

is it correct to saying both aircraft have:
- identical aero mods
- identical cooling systems
- nearly identical max. power output

so decisive is daily situation of aircraft and pilot and mainly qualification and race tactics?

thx
Gibbs

According to our race announcer their engines were built by the same engine guru. I believe that makes them nearly equal under the cowling. As for the other mods there are surely some differences even if only in details. ALL of these things are SECRET territory not for us to know the exact details of.
However: Sunday when Voodoo started first and Strega 7th in the lineup Voodoo left the pack, Strega passed the pack but couldn't gain any appreciable ground on Voodoo time wise. There was about an 8-9 second gap between them. That makes the mods and pilots add up to pretty equal. And while I'm a radial fan it was GREAT to see Voodoo FINALLY WIN!

[Big_Jim]

Re: Differences Strega - Voodoo

According to our race announcer their engines were built by the same engine guru.

Strega's engine was built by Mike Nixon and Jose Flores. Voodoo's engine was built by Mike Wilton.

The only realy connection is the lineage...as Mike Wilton was part of the Mystery Aire crew that bred the Mouse Motor, and Mike Nixon bought out Mystery Aire after Dwight's passing. So the same basic info was there, but they have developed separate programs over the last several years.

[glider90]

Re: Differences Strega - Voodoo

The Voodoo Mike, Wilton. He was one happy guy after the race Saturday, very pleased with the performance it seemed.

[Mluvara]

Re: Differences Strega - Voodoo

According to our race announcer their engines were built by the same engine guru. I believe that makes them nearly equal under the cowling. As for the other mods there are surely some differences even if only in details. ALL of these things are SECRET territory not for us to know the exact details of.
However: Sunday when Voodoo started first and Strega 7th in the lineup Voodoo left the pack, Strega passed the pack but couldn't gain any appreciable ground on Voodoo time wise. There was about an 8-9 second gap between them. That makes the mods and pilots add up to pretty equal. And while I'm a radial fan it was GREAT to see Voodoo FINALLY WIN!

Mike Wilton is responsible for Voodoo's motors. He was with Dago during all their years of success. This year, he went completely through both motors and corrected a lot of issues from previous programs. Until this year, the engines were parts from various sources with various levels of quality. The engines are the same core parts (blower -9, transport case/banks) but some internals are different.

As to aero mods, they are similar, yet slightly different in some areas. Kerch set up Strega way back when. Voodoo was cloned to some extent (incorrectly when the trim tab fluttered in 1998). There's a lot of small details that matter. The radiators and scoops are different too. Strega also doesn't have a header tank for the coolant system.

Michael

[RichH]

Re: Differences Strega - Voodoo

According to our race announcer...

That is your mistake right there! The announcers are usually more wrong than not on technical details. According to them, Czech Mate had the smallest engine in the Gold lineup, and Argo still had a 3350...

[supercub]

Re: Differences Strega - Voodoo

Difference between Strega and Voodoo? About 7.5 seconds on Sunday
Brian

[440_Magnum]

Re: Differences Strega - Voodoo

Sorry for maybe this already was topic, but from what I understand (and this means the other side of the ocean :

is it correct to saying both aircraft have:
- identical aero mods
- identical cooling systems
- nearly identical max. power output

so decisive is daily situation of aircraft and pilot and mainly qualification and race tactics?

thx
Gibbs

Yes, but no... just collecting what I've read elsewhere, no first-hand knowledge:

Identical aero mods: both Strega and Voodoo are built almost identically to Dago Red (the first of that 'pattern' of modifications). Kerch has been involved at some point with all three. So they're a lot in common and pretty much the same. But a lot of subtle differences hide under the umbrella of "pretty much." Look at where the wing trailing edges meet the fuse- different blend/strake design. Subtly different wingtips. The runway-induced prop modification on Strega vs the more conventional blades on Voodoo. And a lot of things too small to see. just maintenance over the years can change the aero subtly- whether gaps are kept tight or not, leakage into and out of the fuse and wings, how smooth the bondo/paintwork is. Both of them look just GLASSY in peoples' photos from this year, they're absolutely gorgeous. Compare the smoothness of Voodoo and Strega in the photos with some of the other top racers which look practically lumpy by comparison.

Identical cooling systems- The scoop shape is pretty much the same and traces back to Dago Red, but I have NO idea what lurks within. How efficiently the radiator(s) inside the scoop eliminate heat changes how tightly the scoop exit door can be closed, and that changes drag. Dago was reported to be significantly different than Strega in there at times, and also reported to carry more redundant systems (ADI pumps, etc.) and thus be a little heavier. But again, all three are close but there's plenty of room for important differences you cannot see easily

Nearly identical max power output- again, those are team secrets and with Merlins there's no direct measurement of torque which (together with RPM) lets you calculate horsepower directly like the radials can. A radial engine is its own dynomometer if the torque readout is calibrated. But they're similar engine philosophies as far as I know... -9 blowers, eliminated intercooler (ADI does the job), rod/bearing/case selection and modifications that allow boost over 130" (whether that's still Allison rods or not I don't know, but I would assume so). What I do know is that after Strega cleared all the traffic, the separation stayed so constant that it was almost like an invisible bar holding the two a fixed distance apart... which also hints that they were making almost identical power. What isn't known publicly is whether Voodoo had more left if needed. Also, as Mike Luvara mentioned, the power DELIVERY (which affects acceleration) is apparently very different. How you do that on a Merlin, I don't know but I can guess- cam profiles? boost regulation? Prop governor response? There's at least two other broad approaches to building race Merlins I've read of.

[440_Magnum]

Re: Differences Strega - Voodoo

That is your mistake right there! The announcers are usually more wrong than not on technical details. According to them, Czech Mate had the smallest engine in the Gold lineup, and Argo still had a 3350...

My skin crawled about those mistakes also. All the Merlins *and* the Griffon are smaller (by cubic inches) than a CM's 2800!

I understand occasionally mis-speaking in a high-pressure, high-speed speaking job like that, but SHEESH the error rate was high! I mean, seriously... just don't offer up engineering details if you don't have them *nailed* in your mind.

[Hans Oberev]

Re: Differences Strega - Voodoo

Like to hear from Steve comparing and contrasting the two planes.

[RichH]

Re: Differences Strega - Voodoo

The scoop shape is pretty much the same

Actually, if you look at it the scoops are quite a bit different. The tip of the scoop on Voodoo hangs down and away from the bottom of the wing quite a bit. There is no such boundary layer separation on Strega's scoop. It blends right up against the bottom...

[Matt Jackson]

Re: Differences Strega - Voodoo

There are Big differences in Voodoo and Strega Aerodynamics. Just ask Stevo!!!

[John]

Re: Differences Strega - Voodoo

...angle of incidence of the main wing reduced(verbal question to Stevo in 2007 regarding Strega). Strega flies a little bit nose higher since the prop thrust line on normal P-51D Mustang is slightly downward in relation to the fuselage reference line.

What other mod differences other than visual I wonder?

[Gibbs]

Re: Differences Strega - Voodoo

Many thanks to all you guys for talking about the "secrets from behind the scenes" - I'm every time learning more!

Does anybody know something about this:
a decade ago or so I remember on race Merlin photos (Sparrow?, Mystery Ayre?) with a lot of bracketry and tie rods for keeping crankcase together under high power settings, nose case brackets etc.
Are this stuff still in use and if not - why?

Gibbs

[Big_Jim]

Re: Differences Strega - Voodoo

Actually, if you look at it the scoops are quite a bit different. The tip of the scoop on Voodoo hangs down and away from the bottom of the wing quite a bit. There is no such boundary layer separation on Strega's scoop. It blends right up against the bottom...

If I recall, the scoop on Voodoo IS Strega's old scoop.