Powering the Critical Mass

LAST EDITED ON Jun-28-04 AT 11:07 PM (CDT)
 
I built my Critical Mass Stunt ship around a tightly fit Saito 72. Times change, conditions change, things evolve. I am presently trying to fit another engine into the Critical Mass. Would anybody care to guess what it might be? Also, as of now I have one new-in-the-box Saito 72 for sale.

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This is what the real one looks like.

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This is what my Stunt Critical Mass looks like. (except mine is in silver now and about to undergo extreme surgery.

Al,

I thought you weren't intending to be involved in any horsepower races. But I hope the 82 works perfectly for you.

Al,
If I guess right do I get the Saito? I'd say your going Saito .82 as per Gordy a.k.a Mr. Ki-61 Tony perhaps?

LAST EDITED ON Jun-29-04 AT 00:27 AM (CDT)
 
Nope to the 82. That would have been too easy. Dan, I lost that debate on horsepower race (big time). Now its "Katey bar the door".

PA 65?

Hmmm.. I wonder if that photo of the full size plane really shows how much hangar rash these planes accumulate, or whether its some trick of the light. The skin looks pretty dented all over.

LAST EDITED ON Jun-28-04 AT 11:28 PM (CDT)
 
I'm sure there is some "puckering" around ribs and stringers but I think most of what you are referring to is swirls of polish and wax. That wing leading edge skin is very thick and unlikely to be dinged, particularly on a racer, which typically, is filled, filed, sanded, sealed, buffed and polished and waxed to aerodynamic perfection for speed around the pylons. Nobody races beat up airplanes at Reno.

And nope on the Saito .65.

I think some kind of pipe engine?. Al please read your email.

Sparky,

Answered your e-mail.

those marks on the leading edge in front of "taco bell" look more like someone hit it with a baseball than polishing swirls.

LAST EDITED ON Jun-29-04 AT 09:25 PM (CDT)
 
Critical Mass and it's outer wing panels have had a couple of mishaps through the years. The outer wing panels are from FB.11 N878M, Mike Carroll's clipped wing hot rod cross country racer. Bought by Sherm Cooper after Mikes death, the airplane won three 1000 mile pylon races and was third in the 1971 Reno Final. In 1972 it had an engine failure and was landed off the airport on a road, at least that was the plan until Sherm got down in the flare and saw 4 inch steel posts there to keep people from landing on it! He made one directional change as the airplane ran out of energy, and it crashed in the desert tearing the gear off and damaging both wings. The airplane was bought by Frank Sanders after Sherm's death and sold on to Jim Mott. It flew with transport Centaurus engines until they all failed, and then it was parked. It was finally sold to Mike Bolander refurbished and repainted in a flame job similar to Carroll/Cooper's look by the Sanders, and sold again, now owned by the owner of Blistex.

The outer wing panels were retained by the Sanders as well as the thoroughly ruined original Centaurus and small racing canopy. Then the wings were sold/traded to Eric Lovellor to complete the 3350 powered TT.20 racer he envisioned.

Crital Mass was originally Blind Man's Bluff, the airplane was powered by an alcohol burning R-3350 and had the cockpit fitted to the rear, a large increase in dorsal area clipped large span horizontal and the FB.11 clipped wings. It looked great in a Travel Air Mystery Ship type paint sceme and after the first three pilots dropped out for various reasons, Skip Holm flew the airplane to many an emergency landing, and finally a gasoline powered finish in a one 1988 race.

The airplane was put up for sale and sold to another owner who bellied the aiplane in at Reno on arrival in 1991. The airplane was then eventually sold to Tom Dwelle, and flown by Skip and Tom variously over the last 8 or 10 years. The airplane, after this photo was taken BTW, was again damaged in a gear collapse on the ramp at Reno year before last. The airplane was repaired and flown and is said to be for sale by some, in case you are interested.

Even though the airplane has a few bumps, it is properly repaired and I think the backlight and the black finish make the leading edges look as bad as possible. In person the airplane looks great. Though Al is right about the racers trick of "profiling" the wings with filler, this airplane does not incorporate this feature. Rare Bear, Dago Red, Strega, Voodoo, and Dreadnought do have filled and profiled wings though.

Al, I really liked your story about the Mustang with the loose oil cap. I looked at all Dad's log books and couldn't find his Mustang ferries down to Sarasota, but there were a few guys buying them on speculation back then in Indiana. I'm sure you two have compared notes long ago.

I left my oil cap off of my Pitts and rolled it upside down once, amazing how big a mess a quart of oil makes!

A two stroke 77 sounds great. Always liked your models.

LAST EDITED ON Jun-30-04 AT 12:33 PM (CDT)
 
I think the airplane would be virtually unflyable if those refections were from dents. I flew a Mustang once which had a small vertical crease in the leading edge about three inches long where somebody had bumped it with a truck. At stall that wing drop was awesome. We had to fix it before we could sell the airplane. Leading edge skins on fighters are usually very thick and strong. Most of the Mustang leading edge skins are .064 (what else do you want to know about a Mustang?). That is thick and strong. Also, the stalling characteristics on a racer are critical because the G-loads in each corner must push the airframe to the edge of accelerated stall. I can't imagine pulling 4-5 Gs in a corner with dented leading edges, (unless, of course, you have a serious death wish).
The Critical Mass is Heavy with its R 3350 engine and hasn't much wing area. I think the airplane would be virtually unflyable if the wing leading edge were significantly dented. I'm still betting on smooth. Lets ask Chris to find out. Don't ask Tom. I tried to buy a T-Shirt from him and he bitched about my e-mailing him. His brother Don is nice though.

If you candle a metal airplane in the light like we do our stunt ships, it isn't going to look too smooth. That wing on Critical Mass is as smooth as can be, and under load of flight, oil canning is always going on. It is a nice looking airplane. I'd fly it.

By the way, Lyle Shelton told me at four G those wings slow a Fury down 40 Kts. He flew Mike Carroll's on the pylons in 1966.

Al knows this, but another little aside about the P-51 is that the wing was filled and painted at the factory to assure an accurate airfoil. After the airplanes were not delivers in camo, by military order, the natural finish ships wings were painted silver after their airfoil optimization. Cool.

That airplane is in level flight, 1 G, so I would assume the wing is smooth in that photo.

OK Cub .049B with a roots blower and Hillborn direct injection and 90% nitro. Or a P&W R3600? What, what???

Well...You said "extreme surgery" so it can't be the .82 (same case as .72), must be the .91? The nose is too short for you to be switching back to a 2 stroke, with out mucho balast added to the front. Either that, or you have switched brands to something like the new OS 70. Hmmm...I give. What?

I am going to guess it is one of the new (.77?) pipe engines. Hey, you aren't competing with it anyway, and it ought to be interesting.

LAST EDITED ON Jul-01-04 AT 08:13 AM (CDT)
 
Leonard,

I bought the very first Ro-Jett .77, and paid list price to my buddy Richard. It is going into a new Millennium hanging unfinished on the wall. It can be used with a pipe, as can many others, but I will be using it with a home made muffler.

Yeah, you got it. I'm trying to squeeze a 1.7 HP Saito 91 into a tight Saito 72 mount. I considered the Saito 82 but the 91 is considerably more powerful, weighs less than an extra ounce, and has the reputation for vibration free operation. Early reports on the 82 are mixed. To fit the 91, it is taking some engineering, and quite a bit of machining of UC carb, mounting crush plates and adapters, but somehow, I think I can do it. I built a forward fuselage mockup with laser cut parts which is an exact duplicate of the Critical Mass fuselage excepting skins. I made up the necessary parts in wood and the whole shebang is over at my machining friends house now for duplicating those wooden parts in metal.

The back story is that the Critical Mass was coming out a bit overweight. After all the effort to build it, I didn't want to have it turn out any less than hoped for in the air. To improve lift to handle the extra weight, I am building a new set of flaps with carbon tube leading edges for extreme torsional stiffness.

I always figured the airplane would need some nose weight because of its very short 7" nose, although the wing and nose are the same as my original Sea Furys which required some but not a lot of nose weight with a much lighter engine. With the extra weight of the Saito 72, I figured I would get away with minimum weight in the spinner. Thinking I'd probably need some extra weight anyway, it seems that a slightly heavier engine wouldn't hurt and it could swing a bigger prop to help the Critical Mass to the tightest possible corners and overcome increased drag from the new flaps. Windy ran 15" props and loved the larger engine on windy days. I will hand carve a series of 15" and 16" props to optimize performance. The Saito specification sheet lists the weight of a Saito 72 at 470 grams and mine weighs exactly 470 grams. The specs list the weight of the 91 as 520 grams, or 50 grams more than the 72. My Saito 91 (from Windy's Typhoon) weighs only 495 grams. This is 25 grams less than it is supposed to weigh and less than an ounce heavier than the 72! Windy describes it as being a stunt friendly, low vibration engine that can swing at least an inch longer prop to pull out of hard corners before stall buffet. Now I will also have to build a new cowling, muffler and fuel tank. It is going to be a fall project. I have to finish the Snaggletooth 2 first. I expect to bring Critical Mass to VSC if it lives up to promise. Is should weigh 75 ozs on 680 sq in Sea Fury wing. The design weight was 70 ozs.

I considered using my ex-wife's vibrator, but it turned out to be over the limit on displacement. I think it is a Black & Decker 5 HP, two speed, kick start. I still keep it around for jump starting cars. (She needed it for problems with her back and shoulder, Leonard)

LAST EDITED ON Jun-29-04 AT 08:46 AM (CDT)
 
Thanks Al: I will look forward to see the drawing. I know the new engine will be a Harley-Davidson TwinCam 103, Just kidding, Got no clue. Some kind of radial? Give us a hint?

Wow! Al, it looks awesome already.

YOU are the Master!

I took the liberty of enhancing your photo a little, so we can all easily see what your powerplant is:

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However, I won't spoil your fun by blabbing it to everyone.

(But I'll bet that last custom muffler post is a pretty good clue.)

Great work.

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"Never go to bed mad. Stay up and fight." -Phyllis Diller

Al:

Not many things would get this Minnesotan to Texas but seeing you fly your Critical Mass might be one of them. Wish you were still doing Braniff layovers up here!

Jeff W.

Hi Jeff,

I thought I recognized your name and photo from the Sig contest post. am I right?

Al:

Sure. You used to layover at the Thunderbird in Minneapolis.

The Sig picture was a Cardinal. I destroyed my Tempest sunday at VSC.

Best wishes,