P-51D/H tail question

JohnB · **Posted:** Sun Sep 16, 2012 11:42 pm

Over on the other forum, it was asked why a certain P-51 had a taller tail.
Someone replied it was the P-51H tail ...and it was later applied to Cavalier Mustangs in the 60s.
Then, another person replied that Cavalier did not use the "H" tail, rather something that just looked similar.

I've never thought much about it, I assumed Cavalier used the "H" tail....did they?

JDK · **Posted:** Sun Sep 16, 2012 11:55 pm

P-51D/H tail question
"It's the vertical thing at the back of the airplane, but that's not important right now..." Sorry, just channelling that movie.

Cavalier tails looked similar, were a different structure to the H or any other NAA product. I hope our favourite F-15 driver will confirm!

Regards,

JohnTerrell · **Posted:** Sun Sep 16, 2012 11:57 pm

The extended vertical fin was an item that was introduced on NACA Mustangs, which because of the high speed dives (testing model airfoils mounted atop the wings), they needed more yaw stability. There are even a few photos, I believe, of an NACA P-51B/C with an extended vertical fin. When Cavalier were modifying Mustangs, they adopted the NACA extended vertical fin modification (as the NACA used on the P-51D).

It might not be very well known, but Mike Coutches' P-51D is a former NACA Mustang ("NACA 126"), like Bill Allmon's P-51D "NACA 127", and both still retain the NACA extended verticals.

Mike · **Joined:** Tue May 04, 2004 8:54 am **Posts:** 3333

JohnTerrell, that's pretty much what I posted on the 'other' forum. Perhaps JohnB will believe us now! :wink:

JDK · **Posted:** Mon Sep 17, 2012 12:06 am

JohnTerrell wrote:

The extended vertical fin was an item that was introduced on NACA Mustangs, which because of the high speed dives (testing model airfoils mounted atop the wings), they needed more yaw stability. There are even a few photos, I believe, of an NACA P-51B/C with an extended vertical fin. When Cavalier were modifying Mustangs, they adopted the NACA extended vertical fin modification (as the NACA used on the P-51D).

So am I right that the Cavalier tail has no NAA design input?

Regards,

JohnTerrell · **Posted:** Mon Sep 17, 2012 12:50 am

James, unfortunately that is something I'm not aware of, myself, and look forward to hearing the input of someone who does.

In my post above, I left out the very popular Ed Lindsay Cavalier Mustang (camo paint), which is also a former NACA Mustang (NACA 108), and it too retains the taller vertical end cap from those days. As it was developed into the Cavalier prototype, the taller vertical end cap was copied on Cavalier production (though not necessarily precisely cloned, as I believe that there were some slight differences).

mike furline · **Joined:** Wed May 05, 2004 3:45 pm **Posts:** 2682

Standard

NACA "B"

NACA "D"

Early "H"

Production "H"

51fixer · **Posted:** Mon Sep 17, 2012 7:44 am

I believe that NAA used the NACA data as a basis for extending the Vertical on the H. I think something like the 1st 50 were built with the smaller tail.
I would have to find it and check but that might have been in the Bob Hoover book.

The Inspector · **Posted:** Mon Sep 17, 2012 8:34 am

Just speculation on this, but- NACA did have a whole crowd of engineers and nerds who actually worked on designing future things like rocket powered aircraft and such, the mechanics on the hanger floor were excellent at fabrication and modifications to airframes, there would be no monitary gains to be made by having NAA do any work on last weeks airplanes so my guess is it was all done in house with maybe a couple photos of an 'H' taped to the drafting board for 'eyeballing' so a simple 'hey Dave we need..' request wouldn't have been much of a stretch for them.

ballmon · **Posted:** Tue Sep 25, 2012 3:24 pm

The NAA/NACA taller Mustang verticals are of different construction from the Cavalier modification. The mod was indeed made to increase lateral stability during the dive testing. During a visit with NACA test pilot Bob Champine he related that once modified the Mustang had greatly enhanced stability. It was important to keep the test article tracking absolutely straight during the dive. During the time these Mustangs flew in the care of the NACA, NAA engineers were working closely with them.

Will someone give a clue about posting pictures here and I'll give you detailed pictures of NACA 127.

Bill

51fixer · **Posted:** Tue Sep 25, 2012 5:14 pm

ballmon wrote:

The NAA/NACA taller Mustang verticals are of different construction from the Cavalier modification. The mod was indeed made to increase lateral stability during the dive testing. During a visit with NACA test pilot Bob Champine he related that once modified the Mustang had greatly enhanced stability. It was important to keep the test article tracking absolutely straight during the dive. During the time these Mustangs flew in the care of the NACA, NAA engineers were working closely with them.

Will someone give a clue about posting pictures here and I'll give you detailed pictures of NACA 127.

Bill

Bill,
Welcome to WIX.
I was working for John when your A/C arrived at Pacific Fighters all to many years ago now.
To post pics you need a photobucket type account that links images to a post.

You have to host the pics elsewhere and then link them in a message using the img tag. As Rob stated a lot of us use photobucket.com which is a free service and is easy to use.

So all you have to do is:
Goto photobucket.com & sign up for account
upload picture to your photobucket account
copy img link and post it in your message here

Very simple

Also, please make sure that the image is no larger than 10 inches (720 pixels) wide as a curtesy to those of us with smaller monitors.

From this thread-
viewtopic.php?f=3&t=1822

Pogo · **Posted:** Tue Sep 25, 2012 7:20 pm

Quote:

To post pics you need a photobucket type account that links images to a post.

Or ............ if you volunteer a subscription to this site, like, say $2/month (or whatever you think it's worth), you may load pictures directly to this forum. See the Support/Donate menu choice above. (Not affiliated, just a satisfied customer, etc.)

Randy Haskin · **Posted:** Fri Sep 28, 2012 6:01 am

JohnTerrell wrote:

James, unfortunately that is something I'm not aware of, myself, and look forward to hearing the input of someone who does.

In my post above, I left out the very popular Ed Lindsay Cavalier Mustang (camo paint), which is also a former NACA Mustang (NACA 108), and it too retains the taller vertical end cap from those days. As it was developed into the Cavalier prototype, the taller vertical end cap was copied on Cavalier production (though not necessarily precisely cloned, as I believe that there were some slight differences).

ballmon wrote:

The NAA/NACA taller Mustang verticals are of different construction from the Cavalier modification.

The Cavalier tail is, indeed, the same as the NAA/NACA tail. No differences. Not sure about the comment about "different construction", but so far as external design, dimensions, and how it is affixed to the vertical stab, they are the same. I've never cut open the two tail caps to know if there are internal construction differences. If someone knows some specifics (Bill/ballmon?), I'd love to know the details (please send me an email or PM if you are interested in sharing what you know).

As was noted, the inspiration for the Cavalier tail came from N4222A, the ex-NACA 108. The airplane was purchased by Trans-Florida Aviation with the NAA/NACA tail, and Dave Lindsay liked what it did for the handling/performance of the airplane as a gun platform, along with the low speed stability. He copied it and offered it both on the military and civilian Cavaliers.

And, of course, they are both different than the P-51H tail.

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