A few Questions About the F6 Hellcat

[H. Godwineson]

Sikboy,

Let me reassure you that I do not consider you to be anti-Hellcat!

Once statistics make their way into historical archives they often become "set in concrete," whether they make any sense or not.  One reader of an earlier thread about this topic commented that the Navy was certainly aware of the discrepancy between the Hellcat's actual speed and that given by the air-speed-indicator system.  He included a photo-copy of several pages from the Hellcat's pilot handbook where the pilots were instructed to ADD to the published speeds.  The amounts added varied, depending upon the flight conditions.

Testimony given by a top test-pilot and the Air Intelligence Center should carry more weight that given by the average arm-chair expert.

Regards, Shuckins

[Steven]

I find the tone of this thread to be very cordial and very interesting.  I look to this thread first to see if anything new has been posted before looking elsewhere.  No demands or screaming for change, just a good discussion about the merits of the data.  I may be subjective though, the Hellcat is my favorite PTO aircraft.

[F4UDOA]

Steven,

I don't know how many of my post you have seen so I will start off with telling you that I have my hands on every piece of information on the F4U ever printed anywhere by anyone.

Any NAVAIR docs or otherwise that exist I have with the exception of the British AFDU which I will have soon.

Anyway I have also read the artical by Corky Myer which was published by Barret Tillman of Flight Journal.

1. First off let me say that I believe the Hellcat was a solid 400MPH A/C at 20K or close to that.

2. I have had but no longer have the original test documents of the F6F-5 post air speed indicator fix. I borrowed them from Frances Dean of "AHT" but I have long since returned them. In any case what they did to get top speed was take approx 5 production A/C run them to top speed at various alts and take the average speed. At least half of the birds tested di achieve over 400MPH at alt. However some of them tested were significantly slower brining down the average.

3. In Corky Myers test as well as the Test against the A6M5 and FW190 the F4U is approx. 30MPH faster at sea level and between 5 to 15mph at alt.in the later test. According to Corkey Myer this was because of a more efficient means of Air intake in the F4U. Keep in mind that since both engines are rated for the same power at sea level no advantage or disadvantage is given in AH.

4. In the Vought Archives they have the drag coefficients listed for each A/C listed as

F4U-1= .020
F6F-5= .023

This would account for a speed advantage for the F4U at all alts as long as rated power is the same.

HOWEVER(Vought) they still have the Max speed of the F6F-5 as 400MPH. I am a bit surprised that AH hasn't used the Vought chart since it is as detailed as any I have seen.

5. The F4U-1D in AH is the only A/C I am aware of that is modeled with a drag penalty from external stores Pylons regardless of loadout. Otherwise it would have a top speed of 366MPH at sea level and 417MPH at 20K.

Here is the Vought chart I am speaking of

[Shuckins]

F4UDOA,

Great post!  Would you happen to know the drag coefficient for the P-47?  It appears to be a sleek design in spite of it's great bulk.  Is it's drag coefficient better than that of the Hellcat?

Regards, Shuckins

[Steven]

F4UDOA,  I see your posts on occasion but can't really put anything in particular to your name.  However, much of this stuff is over my head and I'm just enjoying watching the discussion.  I can't really offer anything of use to either side here.  Why do you collect so much technical data?  Do you work on flight models or just like to collect?  Anyway, it sounds as though the Hellcat might be flying around a little castrated.  

Have you seen the new Wildcat models?  I'm VERY to happy to see a possible early-war Pacific direction.  

[Sikboy]

Hmmm... the plot thickens

So what we are looking at is this: The F-6F5 has a top speed of @400 mph at 20,000 feet. This is established through three sources that are mentioned here (and two of those are presented here). These sources are:
1. The Corky Meyer article from Flight Journal. 2. The Vought performance charts presented by F4UDOA and 3. The F6F-5 Pilots manual, which instructs pilots to add a certain number to offset a faulty speedo.

Do I have this correct? If so, this is probably most most compelling argument I've seen on correcting a performance oversite. Not only are the figures being pursued provided, but also an explaination for the discrepency between data sources is also provided. This is very nice work in my opinion to all who have taken part in this discussion.

I'm one of the biggest skeptics when it comes to performance changes, even in models I enjoy flying. But I've been won over in this case. Are there any dissenters left?

-Sikboy

[F4UDOA]

Heyas

I used to have a boat load of data on my webpage but my ISP changed from @home.com to .comcast.net and it porked my webpage. Anyway I haven't had time to repost everything.

The answer to you question Shuckins the Cdo of the P-47 is listed as .022

The Top speed of the P-47 at sea level is listed as 354MPH in a hybred P-47D razorback with a R2800-63. Many have asked for this bird in AH.

Stevens,

I collect the source docs because I realized that most authors of WW2 aviation books just reprint old data and myth. In fact you might think the P-51 won the war by itself. I like to read autobiographies and collect source documents. I am very plane oriented however which does reduce my abilty to comment on some A/C. However I find that aquiring Navy/Marine docs far easier than their Army counter parts.

I reccomend and have these books

Barret Tillmans
Corsair
Hellcat

ZeroJapans Legendary Fighter by warbird history

America's Hundred Thousand by Frances Dean

Classic Warbird Buyers Guild by Jeffrey Ethell

Symposium by the "Socioty of Experamental Test Pilots"
1989 Evaluation of the F6F-5, F4U-1D, P-51D, P-47D-40

Butch O'Hare's Memoirs
"Fatefull Rendevous"

"Wings and Warriors" Donald Engin

"Report Of Joint Fighter Conferance 1944" Schiffer Publishing

There are others but for anecdotal evaluations these are the best.

The Symposium of Expermental test pilots was done by Modern Fighter Pilots and IMO should be taken very seriously since they use modern evaluation techniques. Their finding dispell some myth I think.

[Steven]

F4UDOA,  it sounds like you have quite the collection of data!  I do actually have Tillman's "Hellcat" and then the corresponding "Wildcat" books.  But I'm actually much more interested in air-combat from the Vietnam War and I concentrate my collecting on that subject.  In fact, I really don't know much about WW2 and really only started AH almost 1-yr ago as a small diversion to take during my busy schedule.  However, Aces High proved a lot of quick and fast fun combined with the fact that I was accepted into the best squadron online (332nd Flying Mongrels) which is made up of the best people you can ever know, I have made AH more than just a diversion in my life.  It must be nice for the HTC people to have a job that has such a positive influence on people's lives.  

Anyway, back to topic...  it seems there is some good data evidencing a greater performance for the Hellcat in Aces High, but I'm guessing HTC reviewed all this data during their initial research and then made their choice and I don't see them making any change to their Hellcat model.  I for one don't know which data is correct, but the conflicting data as provided in this thread does make me do some mental gymnastics and really wonder.

[F4UDOA]

Steven,

I have done some serious testing with AH planes compared to Real Life  stuff and what I have found is this.

AH is not only almost always right they are frighteningly almost 100% on. I mean stuff like fuel consumption vrs performance ratio's, top speeds at alt. IAS vrs TAS. Even the smallest details are almost always 100% correct.

However it does not always mean that they use the performance numbers I would like to see. For instance the F6F top speed. Or the charts used for the F4U-4. I don't spend a great deal of time complaining about it though because while I would use different information their information is valid also. Just different from mine.

Personally I would luv to see HTC open up their vault of data(not FM secrets) to the AH community. For me the data is as much fun for me as the game itself. But then again I am a huge geek. Or at least have a Q and A with the community once in a while.

One of the biggest issues I have with HTC is climb vrs acceleration. HTC and many of the math types like to tie them together and I strongly dissagree.

[H. Godwineson]

Steven and F4UDOA,

One of the things that I have always wondered about the Hellcat is this:  Why wasn't the F6F designed "tweaked" as much as the Corsair or Thunderbolt or Lightning were to achieve more performance?

Grumman stuck with the three-bladed, variable pitch, Hamilton-Standard airscrew throughout  the Hellcat's production run.  All other aircraft which used the Pratt and Whitney R-2800 series engines used four-bladed, variable-pitch airscrews, except for the earliest production models of the Corsair.  How much would the extra thrust produced by a four-bladed propeller have helped the Hellcat's performance?  The Hellcat could have easily handled the fat-bladed propeller installed on the later models of the P-47.  One American ace in Europe (I believe his name was Johnson) had one of these propellers retrofitted to his P-47 and it allowed him to outclimb Spitfires.  He stated that "...Never again did an Me-109 or FW-190 outclimb me."  (Paraphrased)  

Perhaps such airscrews were in short supply.  There was a war on at the time, after all, and every aircraft factory in the country was in full swing.  Otherwise, this seems to be one of those relatively "easy" production changes that could have yielded a substantial increase in performance, but which was inexplicably never undertaken.

By the way, there was a design study undertaken by Grumman to install a Pratt and Whitney R-4350 engine in a Hellcat.

Drool!

Regards, Shuckins

[Steven]

I once read somewhere that the Hellcat concentrated on production rather than experimentation.  I too would wonder about a four-bladed prop on the kittie.  The thing that I love most about her is her simplicity and straight-forward design for the job needed.  However, the Hellcat was a very good fighter in its theater of operations and there probably wasn't much demand for improvement considering the F8F Bearcat was just around the corner.  Bummer that the Bearcat just missed seeing action...though it WAS in the theater on a CV nearing Japan just as the war ended.   I think, if I remember right too, the Bearcats couldn't take off because the CV forgot some important parts for the aircraft like tailhooks or something.

[Shuckins]

Steven,

Absolutely right.  The Hellcat's strengths were it's simplicity, performance, ruggedness, firepower, and range.  All of these were major factors in the Pacific.  The Navy's requirements of range and strike capability exacted some performance penalties compared to it's land-based contemporaries.  The Seafire II may have been the best low-level carrier fighter of the war, but it did not have the robust construction necessary for carrier operations.  The only other Allied fighter capable of meeting all of these requirements was the Corsair, and it did not carrier qualify until January of 1945.  Despite its' performance, even the F8F Bearcat could not perform all of the Hellcat's missions.

Perhaps the greatest testimony to its' effectiveness can be found in the following statistics:

1.  In a year and a half of combat operations, Hellcats destroyed more than 5,100 enemy aircraft.

2.  Less than 300 were lost in combat due to enemy air activity.

Captain Eric Brown of the RNAF rated it the most significant carrier fighter of the war.  He further stated it had a major impact on the air war in the Pacific Theater, undoubtedly altering its course.



Regards, Shuckins

[joeblogs]

For what it is worth, you can read the Standard Aircraft Characteristics Chart of the f65-5 at

http://www.history.navy.mil/branches/hist-ac/fighter.htm

I think this is a post-war version of this report given the bueair number system on the side, but I could be wrong.  I have no idea whether any adjustemnt is made for inacurracies in the pitot tube.

If you read the f6f anf f4u pilot's manuals you see charts correcting the Indicated Air Speed measure up about 10 knots for the F6f and down about the same amount for the F4u-1.  I have no idea why such information would not already be reflected in the flight test data.

-Blogs


Your point is well taken.  The data from Air Intelligence has been used by various authors over the years (Unfortunately, not by enough of them.) in their technical histories of the Hellcat.  I first ran across it in an article about the F6F in the October 1974 edition of Wings magazine.  The latest that I have seen it reprinted was in a technical history of the Zero fighter (Can't remember the author's name off-hand, but he had several interviews with Saburo Sakai) which I purchased back in December.

I am certain those reports are still on file somewhere, but getting an actual copy of them would be about as difficult as finding dragons teeth.  I recently e-mailed Barrett Tillman asking for information about Hellcat armament.  He graciously replied to my questions.  I think I will fire off another e-mail to see if he knows how to obtain a copy of these reports.

By the way, if I had known that using the term "paucity" would cause any confusion I would have watched my language!

Regards, Shuckins [/B][/QUOTE]

[joeblogs]

I've always wondered why they did not put four blades on the f6 too.  And it seems paddle blades only show up in Europe.  I wonder why?

-Blogs

Originally posted by H. Godwineson
Steven and F4UDOA,

One of the things that I have always wondered about the Hellcat is this:  Why wasn't the F6F designed "tweaked" as much as the Corsair or Thunderbolt or Lightning were to achieve more performance?

Grumman stuck with the three-bladed, variable pitch, Hamilton-Standard airscrew throughout  the Hellcat's production run.  All other aircraft which used the Pratt and Whitney R-2800 series engines used four-bladed, variable-pitch airscrews, except for the earliest production models of the Corsair.  How much would the extra thrust produced by a four-bladed propeller have helped the Hellcat's performance?  The Hellcat could have easily handled the fat-bladed propeller installed on the later models of the P-47.  One American ace in Europe (I believe his name was Johnson) had one of these propellers retrofitted to his P-47 and it allowed him to outclimb Spitfires.  He stated that "...Never again did an Me-109 or FW-190 outclimb me."  (Paraphrased)  

Perhaps such airscrews were in short supply.  There was a war on at the time, after all, and every aircraft factory in the country was in full swing.  Otherwise, this seems to be one of those relatively "easy" production changes that could have yielded a substantial increase in performance, but which was inexplicably never undertaken.

By the way, there was a design study undertaken by Grumman to install a Pratt and Whitney R-4350 engine in a Hellcat.

Drool!

Regards, Shuckins