D Mustangs with no fillet mod?

[Django]

How many of them are there left? Can't be very many. I was surprised to see this one on the link that Martin posted to the Mustang thread on the other forum.

[mtpopejoy]

Can you explain (for us uneducated) what this mod entailed?
Thanks,
Mark

[daveymac82c]

I will have to assume that the mod django speaking of is the piece added to the vertical stabilizer. It is a good question he is raising.

Cheers,

David

[Jerry O'Neill]

The fillet was a piece added to the forward edge of the vertical fin that extened forward along the fuselage for a couple of feet. It was added after they determined the lateral stability would be better for the "D" models. The earlier, high back P-51's had more surface area to help with directional stability. Later some B's and C's had the fillet added. See pics of P-51B, "Impatient Virgin", on the Oshkosh thread for the images of the fillet added to that aircraft.
Jerry

[The Inspector]

The dorsal fillet (you fill-ay a fish, you fillet an airplane) was added to correct a percieved tendency for the aircraft to 'fishtail' slightly at certain airspeeds after losing a considerable amount of wetted area when the fuselage went from B/C razorback to bubble canopy version is what I've read and heard over the years.
Don't know the truth of it but I think the D looks cleaner and more lethal without the fillet fairing-

[valdez25]

Where was that picture taken?

[drgondog]

The fillet was added, starting with D-10 (and subsequent K-5) as a production mod, while all the P-51D-5 and K-1 had the fillet retro fitted.

Many B/C's also received the fillet in the Sept-Nov 1944 period

If the photo shown is the correct serial number it was one of the first 100 D's (~) and showed up in MTO and ETO in May/June 1944.

as noted earlier, when the turtleback was removed for the D, the ship had a tendency to yaw >400 mph and particularly in high speed dive.

The condition persisted, somewhat alleviated, until the H tail came along.

[mtpopejoy]

Thank you for the explanation guys.
I am know edumacated.

[Jerry O'Neill]

Where was that picture taken?

I would say the SAC Museum, since that is their B-17 in the background.
CORRECTION: Per Django's post: Hill AFB Musem not SAC.
I guess I'm getting confused as I get older!
Jerry

Last edited by Jerry O'Neill on Thu Aug 14, 2008 1:45 pm, edited 1 time in total.

[Saville]

I used to believe the above:

that the dorsal fin was added to the D model only, and it was because the fuselage was cut down. that's what all the books said.
However recent reading of some T.O.'s issued at the time show this may actually not be the case:

Several crash reports tell of P-51B's and C's crashing because the
horizontal stab was torn off during maneuvering. The report says:

"Unless a dorsal fin is installed on the P-51B, P-51C, and P-51D airplanes, a snap roll may result when attempting a slow roll. The horizontal stabilizer will not withstand the effects of a Snap Roll. To prevent recurrence the stabilizer should be reinforced in accordance with T.O. 01-60J-18 dated 8 April 1944 and a dorsal fin should be installed. Dorsal fin kits are being made available to overseas activities"

A previous entry for another crash:

Sections II and III of T.O. 01-60J-18 had not been accomplished. The
stabilizer was approximately 20 percent below the strength of a completely reinforced stabilizer. It is believed that this type of failure will be completely eliminated after compliance with T.O 01-60J-18 and the installation of a Dorsal Fin and reverse rudder post tab."

A Supplement to Basic Technical Order (From old Hap himself) says:

"1. Due to horizontal stabilizer failures which are believed to have
resulted form slow rolls, all P-51B, P-51C and P-51D airplanes will not perform slow rolls pending the installation of dorsal fin and rudder reverse trim tab, and compliance with T.O. No. 01-60J-18."

Part of this T.O. 01-60J-18, it seems, was to "...use 1/4" rivets rather than 3/16" to attach the elevator outboard and rudder upper hinge fittings,....to stabilizer ribs, providing additional shear strength....."

Also, I guess that drilling out the rivet holes to take the larger rivets
didn't weaken the riveted pieces any - they must have had enough meat left over.


Also you can see photos of P-51B's or C's with the dorsal fin:

http://www.mustangsmustangs.net/p-51...tary/eto/6.jpg

Last edited by Saville on Thu Aug 14, 2008 1:45 pm, edited 1 time in total.

[Django]

The plane is at Hill AFB in UT. I have been trying to find info on the airframe. Couldn't find it in the registry P-51 page, yet a search in google turned this up!

http://www.warbirdregistry.org/p51regis ... llafb.html

I have no idea how to navigate to that from the main P-51 page and the serial isn't listed there either. According to the listing, it is an assemblage of parts representing that serial number. I found the serial # at mustangsmustangs and did a search in google to find the Registry page.

[Jack Cook]

Nice looking a/c but to say it's marked like the one chesley Peterson flew would be a tad inaccurate

[Django]

I think Up Upa Epops is a good restoration to illustrate the field mod, as to me at least, it looks like it was added on later with the different finishes on the skin.

[n5151ts]

it was a non flier with missing pieces and I think the tail part you are talking about was off a T 6 to fill the hole...or so im told

[Django]

Nice looking a/c but to say it's marked like the one chesley Peterson flew would be a tad inaccurate

Haha, just a lil' bit...