Al's Drawings and Photos

I was very pleased to learn of the printing capabilities of my favorite print shop. They are easily able to enlarge drawings and photos to nearly any size you need.

The first photo shows a two step 8x enlargement of a Tempest V drawing with amazingly little loss of detail.

The next Photo shows how I had a small color photo downloaded from the net enlarged about 8.25x to Sea fury size because I intended to use an unmodified Sea Fury wing. The final image made is the same size as the next to last but reversed because I habitually draw airplanes with the nose pointing to the left.

The next photo shows the early modifications to the image. I have lengthened the fuselage and added Sea Fury wing data and begun to enlarge the vertical tail. At this point I am still studying many photos to determine how many scale-like details I can incorporate into the model without compromising competition stunt performance.

The next photo shows a half fuselage mock-up used to determining sizes, shapes. intersections and patterns for the eventual construction of the Critical Mass.

The next photo shows a construction photo of the Critical Mass. It is now in silver but won't be finished until I first finish the Snaggletooth 2.

The last photo is the exact scale Critical Mass an 1:1

Now you are going to have to use a 4-blade prop on that, Al. Matt's already contemplating doing that on the Mustang. Gotta keep it authentic.

A short four blade prop looks much worse than an appropriately sized two blade on a semi-scale airplane. The Critical Mass and Mustang both use props which are about one third on the length of the wings. A usable four blade would look like a poor caricature in addition to producing less thrust than an appropriately sized two blade. The original Spitfires, in service, used a fixed pitch two blade prop. With that prop the Spitfire was only 9 MPH slower than with the later airplanes with the metal three blade prop. If a four blade wood prop would have worked better, those early Spitfire would have used them. Two blade wood props can be very efficient and would be a necessity for competitive performance. Still, it is only a bolt on device and can be changed, as necessary, with no more harm than screwing up a perfectly good spinner.

The difference, of course, was that the three blade metal props were variable pitch (and later, constant speed), with the advantages that come with that feature (takeoff and acceleration).

Oddly enough, Rotol reverted back to the wooden blades with the later multi-bladed props.

Out of curiosity, what 2-blade prop are you using (or planning to use) on this engine/plane combo?

Leonard,

It will probably be a carved 14.5" with approximately 4" pitch and blade area reduced enough to allow the Saito 72 turn about 9500. This describes the latest prop that I'm currently running on my
BBQB Bearcat. I am experimenting with longer props to increase disk area and static thrust without loading the engine below optimum RPM.

While I am asking, Al, what prop will you be using in the Mustang with the PA for power?

About the same but a 1/2" shorter.

Al,

You build unique airplanes. May I be permitted to say that, while I know that the Critical Mass will be a beauty, I can already see that, even when the model is finished and dressed to the nines, it won't have the æsthetic beauty of your original Sea Furies? The lines just won't flow nearly as well to me.

This is no criticism, merely a statement of taste.

I'd just like to know what those stubby-looking things are at the leading edge near the fuselage - they look like the designer changed his mind about the wing mid-stream. I know they must have had some aerodynamic function (on the full-size plane), but what? Thanks,

Tim,

On the Sea Fury, and the Critical Mass is a modified Sea Fury, the port (left) leading edge extensions housed a carburetor air inlet and an oil cooler radiator. The straboard extension housed a 17 Imp. Gal. fuel tank. The front of the port extension was open on the real airplane. Both leading edge extensions on the Critical Mass are open and contain radiators but don't show much as the leading edge is painted black.

Interestingly, the single seat Sea Fury was a Mk 11, but there were many two seat Sea Furys built. These were Mk 20s. The Critical Mass modifications didn't move the cockpit to the rear. It was a Mk 20. They simply deleted the front cockpit.

Sourdough,

Always appreciate your opinion.

Thanks, Al

you gonna put the scale wrinkles in the wing skins Al?

Very nice job on a unique plane!!

I make wrinkles everywhere and pretend they are depictions of scale wrinkles.

By the looks of the prop, they must have abandoned the opposite turning Bristol for the racer? The Navy used to occasionally get one of those beauts (Sea Fury) to the Naval Test Pilot School where it would tie up outside my office window alongside a Mustang. They were a constant work stoppage issue for me. Flying it must have taken some getting used to (the left rudder thing). Hearing that sleeve valve motor at full song with the individual header pipes was guaranteed to send shivers up the spine, almost as well as the 'Stang. Heck, with a nice planetary gear you could swing that big four blade prop on the model.... The wrong (right?) way!

I really appreciate the unique scale planes. Thanks for sharing the midway pics, she's sure to be a standout.

Steve,

The Critical Mass uses a Wright Cyclone R-3350. The Centaurus Mk 18 just didn't have the necessary "poop" for air racing.