Trojan Query - T-28B conversions to "D"

[lovevintageaviation]

I have a query that some maybe able to help with -

At my local airfield there is a T-28 that flies regularly that was manufactured as a "B" model and was later converted/ upgraded with the modifications and certified as a T-28D "Dash" 10.
I am aware that quite a number of "A" models were converted to "D" models (and incude the Fennec conversions in that)
By all understanding and knowledge this T-28 at the airfield is quite unique to Australia as it is of the understanding that it is the only T-28B converted to a T-28D 'Dash' 10 flying in Aus. The best of my knowledge all the other T-28D's in Aus. have been "A" model converstions to AT-28D's and AT-28D 'Dash' 5 series.

so I wish ask if anyone is aware or have an extensive knowledge of the history of T-28 and be able satisfy my curiosity in on this subject - how may T-28B models were modified and officially certified as "D" models? was it rare occurance for the Airforce to have secured "B" frames or was there more frames available and quite a few converted?

Why this is of interest is that I have conducted some research into the T-28 History and so far by what I remember, I am of the understanding that when the US Airforce 'chose' the Trojan, or effectively upgrading the Trojan for the new counter-insergency aircraft they used the "A" firstly as I understand because of availability of frames, which also the French converted some "A" frames to Fennecs, and secondly because all "B" frames were under contract to the US Navy(Which why the French could not secure "B" frames for this reason) with some exception to this with a limited number of frames precured by the ARMY(? unsure whether they purchased new frames or surplus Naval Frames). So knowing we have a T-28B converted to D is quite interesting
I do have a book on the history of the T-28 however the book has been extensively damaged by water so can't open it to find if it has any information on this.

Cheers

[The Inspector]

I'd wager the 'A' models were first to be modified because they were not the most sought after aircaft on the ready line being saddled with a hard charging FRASIER-NASH R-1300 with a grand total of maybe 800 H.P. A local guy had one he donated to the MoF and the engine sounded like Chitty Chitty Bang Bang on alcohol and it was not the most sparkling performer sometimes appearing to labor just dragging its shadow around the pattern.

[T-28mike]

I just spent an hour researching and typing this answer, only to have Wix log me out, and all was lost when I tried to log back in.... enjoy the second attempt complete with horrible spelling and grammer mistakes (i'm trying to edit them out).

There were a total of 371 AT-28D's converted in three models.

131 AT-28D
190 AT-28D-5
50 AT-28D-10

All AT-28D aircraft were converted from the NA-189 Model of T-28A.
The original proposal and contract specified that only the NA-189 model T-28 A would be eligible for conversion. These were ships with factory serial numbers 394 through 1196 which were assigned Air Force serial numbers 51-3463 through 51-3796, 51-7482 through 51-7891 and 52-1186 through 52-3498. This was because the NA-189 incorporated all of the latest design features and most closely resembled the big engine airframe that they wished to mimic.

All AT-28D-5 aircraft were converted from NA-159, NA-171, NA-174, and NA-189 model T-28A airframes.
About half way through the first block (AT-28D) it was discovered that there were insufficient quantities of 189 series T-28's to satisfy the requirements of the program. The elegible airframes were expanded all the way back to the NA-159 model T-28A. The earliest serial number AT-28D-5 converted was 49-1493, factory serial no. 5.

All 50 AT-28D-10 aircraft were converted from NAVY B model airframes with the exception of 4.
By the time the D-10 program was ready, the supply of available A airframes were exhausted. The many foreign aide programs had depleted the once inexhaustable supply of A model T-28 aircraft. The Fennec program alone had consumed 193 airframes (174 conversions plus spare part donors). Fortunately the NAVY had some B model airframes surplus to their requirements, and these were converted to the D-10's. The existing BuAero number was simply prefaced with the year of original manufacture into a psudo Air Force style serial number format. ie T-28B BuAero No. 137639 became AT-28D-10 54-137639.

The 4 exceptions. There are four AT-28D-10 aircraft whose serial numbers do not match B BuAero numbers or year of manufacture. ie 51-153646. A little detective work shows that by eliminating the 15 from the serial no (recrip of 51) we have 51-3646, which is an NA-189 series T-28A.

There were some C model T-28's that were converted to a facimilie "D" configuration for Zaire. These were not on any D serial or mod sequence lists that I have, and I understand that they were "modified" under a stand alone foreign aide contract, and were never part of any official Air Force D model program.

[lovevintageaviation]

The Inspector thanks for your return

T-28Mike - Just awesome info. And truly appreciate your efforts in your return advice. I knew I would get a response posting the question on the forum but that is fantastic info. When I get the chance in the short term I will try and locate the BuAero No.
Armed with the info I was just thinking how many AT-28D-10'sare still currently flying then?

Thanks again T-28mike for your huge efforts.

[T-28mike]

The number of D-10's airworthy is difficult to say for sure. Most of the information on the registries is 10 to 20 years old. It seems likely that there are 2 or 3 airworthy with several on display and several potentially airworthy airframes held in storage.

[Jack Frost]

In defense of the T-28 A model, I flew that airplane for 40 hours as an Aviation Cadet in Basic Flight Training, USAF. Coming from the T-6G it was quite an improvement. Much easier to taxi. Much more comfortable and quieter inside. Roll rate about the same as a P-51. Better electronics although the tube type UHF radio wasn't much to brag about. They told us the R-1300 produced 900 hp which probably wasn't adequate for the preformance capability of the airframe. And it had hydraulically powered nose wheel steering but about the time I got to them, it had been disconnected due to foreign matter found in the steering cylinders. So we used up alot of brake pads taxiing them. The engine had short stacks and since you only heard one side as they would taxi by, it was a cackling sound on the ground. And that engine had clearance problems with the exhaust valve stems. After take-off you reduced power as soon as you could because the exhaust valves quickly got hot and would stick open with an immediate power loss. About the time you had prepared to put it in straight ahead the valves would cool and release and here came the engine roaring back! Reduce power and there were no further problems on that flight. And there were a few cases of the prop shaft failing and the prop flying off. Too fast advancing the throttle and the engine would hesitate . They told us that was to get us ready for the relatively slow acceleration of the jet engine in the T-33. Maybe so, but i never flew a T-33. Our next step up was the B-25 and all that noise,etc. was back in spades! And those R-2600 didn't hesitate either.

I'm sure the R-1820 version of the T-28 would be alot more fun to fly. But in 1953 the R-1300 version was all the USAF had.

[lovevintageaviation]

G'day Jack Frost

thanks for sharing the info on the 'A' model. There is an A model at our airfield too, build no.50-221. Infact the only model that is missing is a "C" and we would have the compliment, I guess have to factor in we don't have the turbine version as well.
As you refer the note difference between the 1300 to the 1820 is quite noticable and so too the engine Cowls. And was quite surprised, given the Horespower difference that the "A" can pretty much hold its own with the more powerful cousins. The difference between cruise speeds isn't a lot over a set flown distance. But then again given it is a lighter frame and the smaller Cowl "intake" being more streamlined, is still quite remarkable just the same.
And correct me if I'm not right in saying this, It's interesting that North American effectively did not change the undercarriage, the mains at least, through the different series. Noted that there was the change in nose steering and different nose wheels, but comparing the "A" "B" and "D" undercarriages they appear the same. Noting Navy requirements and the T-28 series operated on carriers, it appears North American set out from the beginning design to make sure the T-28A had an undercarriage that could take a bit of punishment.
The A is a nice aircraft, and love the trianer dayglo red & white scheme on the "B"s. Ahh hell love em all

I would have given to have seen the prototype T-28 Tailwheel design fly. It must have been like a T-6 on steroids

Cheers

[SIDSIKO]

Hello T-28Mike and all,

I have been asked to copy and paste this e-mail as a form of reply to this thread, from Aviation Historian, Steve Darke, who for some reason could not register to WIX. I am sure he would welcome any extra input you may be able to offer.

There were a total of 371 (no, 421) AT-28D's converted in three models.



131 AT-28D - Correct, but I believe designated T-28D, not AT-28D. Mod Sequence #’s 1 to 131.

190 AT-28D-5 - Correct, but I believe designated T-28D-5, not AT-28D-5. Mod Sequence #’s 132 to 321.

50 AT-28D-5 - as T-28D-5 converted in 1973. Only difference to T-28D-5 believed to be additional radio equipment (UHF, VHF, FM, HF, VOR, TACAN, ILS, ADF, IFF, and Air-to-Air TACAN). Mod Sequence #’s 001 to 050.

50 AT-28D-10 – Correct, but I believe designated T-28D-10, not AT-28D-10. Mod Sequence #’s 401 to 450.



In addition there were many ‘field’ mods, and many T-28B’s were modified to ‘armed T-28B’s’, almost indistinguishable from the T-28D.



The 4 exceptions. There are four AT-28D-10 aircraft whose serial numbers do not match B BuAero numbers or year of manufacture. ie 51-153646. A little detective work shows that by eliminating the 15 from the serial no (recrip of 51) we have 51-3646, which is an NA-189 series T-28A. 51-3646 was a Fennec. The 4 ‘exceptions’ are not exceptions in fact. They are Bu153646, 153648, 153655 & 153659. All four of which were MAP to Laos.



There were some C model T-28's that were converted to a facimilie "D" configuration for Zaire. These were not on any D serial or mod sequence lists that I have, and I understand that they were "modified" under a stand alone foreign aide contract, and were never part of any official Air Force D model program. I’m not sure that these were ‘D’s. I think armed ‘B’s. Did they have the belly speed brake?



Also see my listing of SE Asia T-28’s at http://www.thai-aviation.net/files/T_28_SE_Asia.pdf



Regards,



Steve Darke

http://www.thai-aviation.net

[T-28mike]

Steve & Sid,

Thanks for the reply.

First, I should have notated that my "D" production tabulation came from an officcial USAF publication (namely the 1978 edition of the illustrated parts breakdown) and therefore could not possibly be incomplete or incorrect (sarc.)

Second, A writer (speller, english major ...)I are not. My point gets lost in my ramblings sometimes (OK, pretty much all the time).

In regards to the 4 exceptions, What I was trying to say was that the 4 BuAero numbers that you list are not BuAero numbers that were assigned to T-28 B production by NAVAIR. B model BurAero numbers were in the 137XXX, 138XXX and 140XXX blocks of numbers. It appears that in addition to the 46 model NA-200 T-28 B airfarmes, there were 4 ea. Model NA-189 T-28 A's modified under that contract. `
It appears as though the powers to be assigned a modified (bogus) number to the 4 airframes in question so that the serial numbers looked consistent (same number of characters) with the former NAVY birds.
This was accomplished by cleverly prefacing the real 4 digit A/F serial numbers (of the Air Force airframes that were modified) with a 2 digit recriprocal of the fiscal year ( in this case 15) inserted after the fiscal year (51), and in front of the actual serial number for the respective ship. ie 51-15XXXX.

The two former Zaire aircraft that I worked on were definately neutered "C" model airframes (all arresting gear equipment removed, and aft fuselage "cut-out" faired over). They employed the "modified" wing that had six hard points (standard production B and C had two hard points. Some were later modified to a wing with six external store locations) Both had speed brakes when I was involved with them, and I have no reason to believe that they were ever not installed ( installation looked like un molested factory parts). There was nothing else unusual about the airframes as I recall.

Steve, e-mail me I have some material you might find interesting.

[SIDSIKO]

Hi T-28mike,

PM sent to you

Regards

Sid