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Grumman F8F-2 Bearcat


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#31 ruzlkampf

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Posted 22 December 2008 - 05:23 AM

Got the cowling all stuccoed up, and have started sculting the wing-tips and smoothing the wings. Whoohoo! here's another angle of my new tail-feathers. Do these make my rear-end look fat?! Bwhahah. Actually looks kinda cool with the larger fin fillet and wing root fillet on too. This increases elevator area by a scale 3-1/2 sq./ft. without increasing span and drag.
Something interesting. When Grumman was increasing the rudder height from the -1 Bearcats to aide directional stability with the 150 gal. drop tank attached, to the -2, NACA wanted them to raise it 16 inches after aerodynamic tests. Grumman only raised it 12 inches, cause the remaining 4 inches would have required an entire redesign of the aft fuse to compensate for the loads!!! Sooo...taller would mean more drag and weight for strengthening. I just added another square foot to the cord at the upper edge, and called it good. A little more surface area for 'yanking and banking' around the pylons at 475mph+ is not a bad thing.(and I just think they look cool too. :blink: )
The Bearcat was on the margins of stability for such a small airframe with such a powerful engine, even when it ONLY had an R-2800. This baby has another 1000hp, and goes 100+mph faster than a stock Bearcat. Awe inspiring when I think about it building this thing. More pics when batteries are charged!

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#32 Allok

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Posted 22 December 2008 - 05:50 AM

Looks great to me.

The most famous Aussie brand name would have to be XXXX beer (Kinda figures)

Did Australia win the America Cup? :blink:
Don't you wish some people would use glue...
Instead of lipstick?

#33 DaveJ

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Posted 22 December 2008 - 05:56 AM

Something tells me this build is gonna redefine "taking a trip to Russville"! :blink:

Can't wait to see what's next!
Time flies like an arrow. Fruit flies like a banana.

#34 LSP_Kevin

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Posted 22 December 2008 - 06:26 AM

Yeah, the Aussies won the Americas Cup, in eighty-something. They turned up in a contraption made of empty beer cans (XXXX among them), and towed behind a '74 Torana. Bob Hawke proclaimed it National Hangover Day and the boat was subsequently cashed in at the recycling depot for $47 - that's 11 slabs in eighty-something money (a slab = 24 beer cans/bottles). We haven't won one since. In fact, I don't think we've ever been invited back...

Russ, anything but Telstra.

Kev

#35 Allok

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Posted 22 December 2008 - 06:33 AM

How about "Quantas"? :blink:
Don't you wish some people would use glue...
Instead of lipstick?

#36 LSP_Kevin

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Posted 22 December 2008 - 07:13 AM

How about "Quantas"? :blink:


Only if you spell it correctly Keith!

Kev

#37 Spads57

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Posted 22 December 2008 - 07:24 AM

Russ,
Fantastic project.Those stubby little wings are just outstanding along with the tall tail.As always excellent craftsmanship throughout.Generally I don't care much for having a pilot onboard,but in the Race Bearcat it just looks right.Keep us post my friend.
Highest Regards,
Gregory Jouette

#38 fastzx

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Posted 22 December 2008 - 10:44 AM

Russ,

I got to see Rare Bear in action at Reno in 1996. Wow!

I sneakily talked my wife then (now ex-wife) into a "vacation" We flew in and started in Sacramento, drove down to Yosemite, and spent the night nearby,
toured the park the next day (she didn't want to hike by the way).

Then we drove up to Lake Tahoe , but my ultimate goal, was the Reno Air Races!

The world's fastest motor sport...there is nothing like it WWII modifieds racing 30 -50 feet off the ground at 500+ mph!

One of the most memorable days of my life outside the day my son was born.

I paid my money for a pit pass and was not at all disappointed... it just does not get any better than that.

Anyone not familiar with Unlimited Air Racing tells me that Nascar or Drag Racing is the fastest motor sports. Ha! I laugh at these poor misguided souls.

I've been to Indy 500, drag races, and Nascar...they don't even come close!!!!

I'm looking forward to seeing your "Rare Bear" finished as it brings back fond memories. Great looking so far!

Jon

" There are only two types of aircraft - fighters and targets."

- Doyle 'Wahoo' Nicholson, USMC.


#39 big matt

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Posted 22 December 2008 - 02:26 PM

Hey Russ! This thing is gonna be coooooool! I was thinking about your sponsor though. Chico's Bail Bonds kinda rang a bell for me. You know, Bad News BEARS and all.

Keep up the great work buddy!

Btw, still not sure about the 105. But I have my eye on another hair dryer...

Matt
We are all your base.

#40 Texas

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Posted 19 January 2009 - 03:53 PM

Your doing some inspiring work on this build. Looking forward to seeing more progress.

Texas :unsure: :blink: :ph34r:

#41 ruzlkampf

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Posted 20 January 2009 - 10:29 AM

Hey Guys, Thanks for the input! :lol: This is far from a dead project...been working on it for the last 2 weeks. Really leaning on the pancake build to get it done by the dead-line, then 'elbows 'n tail-feathers getting these Reno air racers completed. Hmmm, might have to post some recent update pics methinks.
Noticed in the background of some of your build pics that you're into car models too, Texas! I've acquired some NASCAR decals for a Valvoline sponsored car driven by Mark Martin(#6) during the 1996 season. They'll swoop over this Bearcat really nicely. Decided the Mustang will be sponsored by the 'dark-horse' Aussie contingent, cuz they actually had some Mustangs over yonder that must have crashed in a lake or out in the Outback somewhere and would've been re-built as a racer. Got a really cool paint-scheme set-up for that bird already. Up-date pics soon! Russ

OK, here's a teaser pic of the wingtip mod taken before smoothing the wing out and sanding the upturned swoop into shape. Don't want to show too much yet and spoil the surprise! :lol: he he.

a.JPG

#42 r0t0rdr1ver

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Posted 21 January 2009 - 10:01 AM

Hi Russ! It seems the more I browse around the forums, the more projects of yours I find! How many do you have on the go right now? The Bearcat is looking fantastic! But then again, all your builds are an inspiration. Keep it up, I'm learning a lot from watching you work...really great stuff! Cheers.

#43 Chris McMillin

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Posted 20 February 2009 - 12:44 AM

Cool model. I have had the pleasure of growing up around racing, and the "Bearcat", and thought I'd note a few things.

The cowling that is mounted on the airplane now is from a DC-7 airliner. It slows the airplane at least 5 knots. The airplane operated with the more streamlined stock cowling until the late eighties and was changed to make it easier to remove for maintenance. The reason it is a slower design now is that it changes the fuselage dimensions and fineness ratio from the stocker, which had a sort of early "area rule" contour where the widest part of the fuselage was at the trailing edge of the wing. It is not that way now.

The big spinner was always a dream of the early crew. It started with a pointy DC-7 spinner and prop, because they were cheap and available. The prop was changed to an Aeroproducts and a P-61 Black Widow spinner was added. Then a P-51H spinner was used. The aerodynamicist's always said a four foot long spinner was what was needed to streamline the fuselage correctly and with the custom job on it now they finally achieved that goal.

The spinner shape and size is only half the story on aircooled engines, the afterbody that fairs the high pressure air from the slot in the cowling to the cylinder faces within the cowling has a huge effect to internal aerodynamics in these racers with radial engines. The afterbody is the same diameter as the backplate of the spinner and then reduces in size to meet the crankcase diameter and this decreases the velocity of the air so the cylinders cooling fins will accept the airflow through them in an efficient manner. This reduces drag significantly.

To get the most out of the internal aerodynamics, the now hot cooling air now has to be guided out in the most efficient way as well. The exhaust ramps are over double the size and depth of the stock Bearcat and have a surface boundary layer slot to help the ejected cooling air stay attached to the slipstream of the air flowing over the outside of the airplane.

The exhaust stacks of the engine are positioned so as to create a "jet pump" and they effectively suck the air out of the cowling as fast as it comes in with, at some speeds and conditions, a certain amount of beneficial thrust.

What I always wondered was what it would have done to the top speed to make a composite cowling of the original Grumman shape along with the custom spinner.

The canopy is the way it is so the opening is stock in case of escape, and it can be opened for take-off and landing. Lyle Shelton flew it that way though others that have flown it since like John Penney and Skip Holm did it differently. I dig the Cosmic Wind canopies from the 60's like Conquest 1 and Miss Candace too, but the Bearcat never had one.

The P-3/Constellation hybrid propeller needs overhauled but also was built specifically for the straight line 3KM record attempts. It was not ready for the record attempt and the airplane broke the record twice with the Aeroproducts prop, the second time was the following day at the present 528 mph average. The gyroscopic precession of the three bladed hybrid is very strong and requires a lot of aerodynamic control surface deflection when the airplane is changing direction around the race course. Essentially it requires left rudder whenever pitch up control, or positive G, is required. It might be that it requires as much drag from the control deflections as it adds in top speed. Not enough testing has been done to figure out the benefits of the prop as it runs so infrequently. Lyle Shelton was the owner and pilot for many years and he ran it the way he felt rather than a strict test regime where records could be kept of it's performance at different power settings and conditions while comparing equipment. Not a slight to the most successful race pilot in history, just a note of fact. His ship, his dime, he did it his way.

The airplane was sold to a Texas billionaire in 2007 and now is flown by John Penney for the foreseeable future. After last years fiasco John might step down and several pilots might be in line for the seat in the worlds fastest piston powered, propeller driven airplane, N777L.

Chris...

#44 ruzlkampf

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Posted 20 February 2009 - 11:28 AM

Whooo, fascinating stuff, Chris! ;) It's really tough finding out any 'speed secrets' these Reno teams do internally to their aircraft. They hold their cards as close to their chests as most Formula 1 teams as far as mods.
Excellent info on the cowling! I wondered if it was custom shaped, or based on an existing design. I'm still going over mods made to Conquest 1, such as the filled in oil-cooler/inter-cooler ducts in the wing-roots with a water cooled boil-off radiator sump internally in the wing....and the fuselage strakes that extended from behind a new wing/fuselage fillet. Also, Conquest 1 had an enlarged fin filet for increased area in front of the rudder. I understand RareBear has a slight problem with yawing at speeds over 490, and thought that might have been why the 3-bladed prop was 'shelved'. Interesting to know it's just being rebuilt.
Yeah, I'm just going with a 'cosmic wind type canopy' cause I think it looks tough. I'd hate to have to jettison that in an emergency though. The panel it sat on in Conquest 1 looked like it would take the pilots head off at any kind of speed. That'd be less than optimal! ;)
Still planning on finishing this build in the near future, but real life commitments with 1/1 scale models are consuming all my time currently. When it comes time to finish, I hope you'll feel free to comment with more fascinating 'insider' information, Chris! Excellent stuff! Russ

#45 Texas

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Posted 22 February 2009 - 05:21 AM

Noticed in the background of some of your build pics that you're into car models too, Texas! I've acquired some NASCAR decals for a Valvoline sponsored car driven by Mark Martin(#6) during the 1996 season. They'll swoop over this Bearcat really nicely. Decided the Mustang will be sponsored by the 'dark-horse' Aussie contingent, cuz they actually had some Mustangs over yonder that must have crashed in a lake or out in the Outback somewhere and would've been re-built as a racer. Got a really cool paint-scheme set-up for that bird already. Up-date pics soon! Russ

Yes I build almost as many cars as I do Aircraft and the NASCAR decals come really handy. I have also found that oil company decals from the train guys are very handy on race cars.

Looking forward to seeing more of your build. It's looking great

Texas




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