Go Back  PPRuNe Forums > Misc. Forums > Aviation History and Nostalgia
Reload this Page >

Grumman Bearcat inspired by FW-190?

Aviation History and Nostalgia Whether working in aviation, retired, wannabee or just plain fascinated this forum welcomes all with a love of flight.

Grumman Bearcat inspired by FW-190?

Old 1st Jun 2021, 08:15
  #41 (permalink)  
 
Join Date: Jul 2007
Location: Auckland, NZ
Age: 77
Posts: 696
Originally Posted by rich34glider View Post
They were designed to fail at the hinge line at 7.5G as a weight-saving measure
According to Wikipedia, the problem was that the wing tips didn't fail simultaneously, so they ended up limiting the whole aeroplane to 7.5g.

FlightlessParrot is offline  
Old 2nd Jun 2021, 07:17
  #42 (permalink)  
 
Join Date: Apr 2009
Location: West Woop Woop
Age: 50
Posts: 48
That was the end result - via explosive bolts designed to even things up if only one tip failed, that were subsequently removed - that would have been a wild and alarming ride!
rich34glider is offline  
Old 2nd Jun 2021, 08:34
  #43 (permalink)  
Gnome de PPRuNe
 
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 57
Posts: 8,794
By the hinge line, do you mean the wing fold? The wing fold is between the flap and the aileron, the wing tip jettison was further out, leaving a stub aileron.

Funny thing, I've never seen The Fighter Collection's Bearcat with her wings folded in 40 years (yes, she joined Stephen Grey's collection 40 years ago!) yet the second aircraft they operated for a short while certainly sat on Duxford's flight line with her hands up.
treadigraph is online now  
Old 2nd Jun 2021, 10:22
  #44 (permalink)  
 
Join Date: Mar 2002
Location: near an airplane
Posts: 2,027
Originally Posted by FlightlessParrot View Post
This thread started, long ago, with examination of the idea that the F8F was inspired by the FW-190 towards the idea of putting the largest engine in lightest airframe.
The practice of marrying a great big engine to an afterthought of an airframe started when they invented air racing. Just look at the Granville Gee Bee models.

I think it is more likely that development of one fighter was inspired by the fact that the current crop of steeds was being outperformed by the opposition's models. Fighter performance is very dependant on altitude, weight, temperature and the handling pilot so just stating that one type was meant to outperform or mimic one other type is a very broad statement. Surely, the F8F was meant to do better in one specific corner of the envelope, without sacrificing too many of the other corners, but without knowing what the designer was thinking at the time, any other statement about his inspiration is most likely over-simplified.
Jhieminga is offline  
Old 3rd Jun 2021, 07:11
  #45 (permalink)  
 
Join Date: Apr 2009
Location: West Woop Woop
Age: 50
Posts: 48
Originally Posted by treadigraph View Post
By the hinge line, do you mean the wing fold? The wing fold is between the flap and the aileron, the wing tip jettison was further out, leaving a stub aileron.

Funny thing, I've never seen The Fighter Collection's Bearcat with her wings folded in 40 years (yes, she joined Stephen Grey's collection 40 years ago!) yet the second aircraft they operated for a short while certainly sat on Duxford's flight line with her hands up.
I copied the quote from wikipedia, which is what I looked at to confirm what I recalled reading in a book somewhere. If "hinge-line" is incorrect and you know correct alternative description then feel free to correct it. It would obviously be a good idea to have some aileron control post wingtip departure!
rich34glider is offline  
Old 3rd Jun 2021, 07:39
  #46 (permalink)  
 
Join Date: Mar 2002
Location: near an airplane
Posts: 2,027
Copied from: https://ww2aircraft.net/forum/thread...bearcat.50532/

Here is a story from Corky Meyer, originally published in Flight Journal:

The engineers were trying to build the lightest airplane with the biggest motor and still make it capable of surviving carrier landings. To do this, they designed the wings lighter and weaker than normal but intended to shed about three feet on each side should it be overstressed. It could fly back to the carrier and land, even if only one wing separated. The concept worked in testing, and everyone was happy until it hit the fleet.

Pilots loved the airplane because it was fast and had the fastest rate of climb of any propeller-driven fighter in the War. Unfortunately, after a few weeks of glowing operational reports on the Bearcat, word came back that a pilot had shed one of its two wingtips in a dive-bombing-run pull-out and had augured in. Several similar occurrences followed, and the Navy and Grumman became greatly concerned. The flight envelope of the Bearcat was severely restricted, and it was immediately removed from carrier operations.

The Navy and Grumman agreed that a better way to guarantee the wingtip separation was to put a 12-inch strip of prima cord (an explosive rope used to detonate dynamite) just outboard of both wing break joints and have a set of electrical microswitches at both break joints. These microswitches would activate the other tip’s explosive device at the instant the first wingtip came off. (We called them “icebox” switches, which shows where we were in technical antiquity!) The ground tests were spectacular, to say the least. Lots of noise, smoke and flying airplane pieces.

After several successful ground tests, we rigged up a Bearcat with this “Fourth of July” system, and I was sent off to do my job as a test pilot.

One of the tips was structured to come off at 5G, and according to theory, the icebox microswitch in the other wing would electrically activate the prima cord and blow the other tip off at the same instant. Three hundred and twenty knots at 7,500 feet altitude in a 30-degree dive angle was selected as the demonstration point. To record the action, we had photographers in chase airplanes on both sides of my Bearcat. I pulled 6G to ensure the 5G rivet joint would fail and activate the other tip explosive.

Lo and behold, the genies of fate again urinated on the pillars of science. With an impressive flash of fire, smoke and debris, one weakened tip left the airplane as predicted at 5G, but the other remained as fixed to the wing as ever.
From the cockpit, a Bearcat appears to be nothing more than a huge engine with tiny wings. However, to look out and see that not only has one short wing become even shorter but also that the other one is full of holes gets your immediate attention.

One of my chase pilots came in and inspected the wing damage. He saw a large hole in the bottom surface, proving the prima cord had indeed fired, as predicted, but the wingtip had remained firmly attached even though the 12-inch hole was in the most critical stress area—the lower skin, or tension area. Good old Grumman Ironworks! Fortunately, the 12-inch hole did not cause any aerodynamic disturbance as might have been expected, and I had already landed the F8F with single tips removed and was ready for the experience, so the landing was uneventful. Back to the old drawing board.
The project engineer suggested 26 inches of prima cord be used on the next flight, after ground tests were run to check whether that amount of explosive would affect proper wingtip severance. On the next flight, when I pulled 6G, both tips departed as planned amid much smoke and parts flying off the airplane.

Both chase pilots were much more excited than I was by the visual effects; I hadn’t seen them because my eyes were glued to the accelerometer in the cockpit. They said it looked as if the airplane had blown up when both tips blew and both the ailerons and wingtip sections departed the bird. There were two very smoky explosions as two wingtips and two aileron halves came off in very rapid succession along with much shattered metal. The wingtip ends were cleanly severed as hoped for. There weren’t even small pieces of metal outboard of the end rib to suggest an explosion had done the surgery. The test was considered a great success by Grumman and the Navy. More important, I had survived the tests, which I considered an even bigger success.
There is more info on the safety wingtips here: (Link edited to avoid translation issues...)

Jhieminga is offline  
Old 4th Jun 2021, 07:37
  #47 (permalink)  
 
Join Date: Apr 2009
Location: West Woop Woop
Age: 50
Posts: 48
Originally Posted by Jhieminga View Post
Great info Jhieminga, cheers!

Looks like the wiki description of "the hinge line" was referring to the actual aileron hinge denoted by the red line fore/aft about halfway along the aileron in this pic from the link:



Last edited by rich34glider; 4th Jun 2021 at 07:40. Reason: Picture not copying to post
rich34glider is offline  
Old 4th Jun 2021, 10:31
  #48 (permalink)  
Gnome de PPRuNe
 
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 57
Posts: 8,794
That sounds authentic. I think Rare Bear has the wings clipped at the same point - sure I've seen a pic showing just stub ailerons; probably Darryl Greenamyer's Conquest One did too.
treadigraph is online now  
Old 5th Jun 2021, 02:28
  #49 (permalink)  
 
Join Date: Mar 2005
Location: N/A
Posts: 4,035
http://thanlont.blog#spot.com/2011/02/conception-of-f8f-bearcat.html (remove the hash for the link to work)

The Conception of the F8F Bearcat

The interweb would have you believe that the F8F Bearcat resulted from a Grumman evaluation of the Focke-Wulf Fw 190 accomplished in early 1943, possibly even at Grumman's facility at Bethpage on Long Island, New York.

There is a report of a captured FW 190 arriving at Wright Field, Ohio in August 1943. However, it seems very unlikely that it would have passed through Bethpage first for an evaluation by a Navy contractor, although I'm sure that it would have been a closely held secret if it did.

As best I can determine, the F8F originated with a memo from Roy Grumman to Chief Engineer Bill Schwendler dated 28 July 1943 requesting a predesign of a small fighter built around the most powerful R-2800 engine available and providing some additional guidelines. It was reportedly the result of previous discussions between those two dating back to at least late 1942.

A predesign drawing by Dick Hutto dated 20 August 1943 indicates that the basic size and shape, including a bubble canopy, of the Grumman G-58 were well established by then.


The story that seems more credible (and supported by contemporaneous documentation) is that Grumman's Bob Hall and Bud Gilles went to England in September 1943 to fly a captured Fw 190. I haven't seen Hall's report, but they were undoubtedly impressed by its speed and maneuverability. It seems likely that they would have returned to Bethpage with the intent to match, if not exceed, its performance and handling qualities with the new Grumman fighter that they had already envisaged.

It therefore seems almost certain that the basic philosophy that shaped the F8F was not the September FW 190 flight evaluation but the result of 1942 combat experience in the Pacific vis-a-vis the Mitsubishi Zero, the need for what amounted to a fast-climbing interceptor, and the requirement for a fighter the size of a Wildcat to operate from the small decks of the newly created escort carriers.

The Navy ordered prototypes of the G-58 in November 1943 and designated it the F8F. The first one flew only nine months later, in August 1944. Deliveries of the first production aircraft were made in February 1945.

However, the first air group equipped with F8Fs arrived in the Pacific just days too late to participate in the war. (In fact, it was first Navy carrier-based aircraft initiated after Pearl Harbor to get that far; most were canceled before reaching fleet squadrons.) Within a few years, it was supplanted by jet fighters and relegated to a training role.
megan is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.