OR.318 / NA.45 Advanced Jet Training Aircraft Joint Requirement, 1953

In 1953 the Air Ministry and the Admiralty issued a joint requirement for a two-seat advanced trainer for operational training at OCUs with fighter-like handling and a maximum speed of Mach 1.0. It was to be armed with a single 30mm ADEN with provision for rockets and bombs and the ability to train pilots on Blue Jay operating procedure. Eventually OR.318 and NA.45 were withdrawn in October 1954 and the Hawker Hunter T.7 was the successor. It was the favoured to meet OR.318 but fell short of the required speed, the P.11 was fasrest but could not meet the endurance requirements, the 725 with the BE.26 failed to meet the requirements but did with the PS.37. Overall the 554 came the closest to meeting all the requirements.

The four submissions to meet OR.318 were:
Avro 725 based on the Avro 720
English Electric P.11 based on the P.1B
Hawker P.1101 based on the Hunter
Supermarine Vickers Type 554 based on the Type 545 Developed Swift

The following data comes from the Tender Design Studies submitted as quoted in AVIA 54/1189.

Avro 725
With 1x 6,500lb Bristol B.E.26R: 11,472lb AUW; 585kts (M 1.02) at 40,000ft; 720 gals fuel; 1,100nm range with external fuel; 48,000ft service ceiling; 7.3 mins to 45,000ft; 1800yds TO to 50ft; 1560yds landing from 50ft
With 1x 10,750lb de Havilland PS.37: 16,030lb AUW; 660kts (M 1.15) at 40,000ft; 720 gals fuel; 1,100nm range with external fuel; 52,000ft service ceiling; 5.5 mins to 50,000ft; 1300yds TO to 50ft; 1650yds landing from 50ft

English Electric P.11
28,658lb AUW; 1x 14,000lb RR Avon RA.24R; 1155kts (M 2.0) at 40,000ft; 600 gals fuel + 250 in slipper tank; 1,100nm range with external fuel; 49,000ft service ceiling (no reheat), 53,000ft (with reheat); 6.0 mins to 50,000ft; 1600yds TO to 50ft; 2100yds landing from 50ft

Hawker P.1101
16,613lb AUW; 1x 10,500lb RR Avon RA.23; 530kts (M 0.92) at 40,000ft; 420 gals fuel; 1,100nm range with external fuel; 47,000ft service ceiling; 11 mins to 50,000ft; 1400yds TO to 50ft; 1500yds landing from 50ft

Supermarine Type 554
With 1x 17,500lb RR Avon RA.19R: 22,010lb AUW; 575kts (M 1.0) at 40,000ft; 690 gals fuel; 1,200nm range with external fuel; 53,500ft service ceiling; 5.5 mins to 50,000ft; 1750yds TO to 50ft; 1700yds landing from 50ft
With 1x 21,750lb RR Avon RB.106R: 26,000lb AUW; 690kts (M 1.2) at 40,000ft; 820 gals fuel; 1,200nm range with external fuel; 56,500ft service ceiling; 4.0 mins to 50,000ft; 1600yds TO to 50ft; 1800yds landing from 50ft

Hi,

here is the Avro-725 artist drawing.

Couple of shots of the 725 model from the Avro Museum... Family resemblance to the 720 is quite clear...

Zeb

[br /]Avro 725 by Martin Winchester, on Flickr

[br /][Avro725 by Martin Winchester, on Flickr

[br /][Avro 725 by Martin Winchester, on Flickr

[br /]Avro 725 and 720 by Martin Winchester, on Flickr

Interesting design. Could've made a useful light fighter in the F-5 class.

I have an unpublished Barrie Hygate drawing of the Type 554. Its the developed Type 545 with twin side-by-side seats, effectively.

PaulMM (Overscan) said:

I have an unpublished Barrie Hygate drawing of the Type 554. Its the developed Type 545 with twin side-by-side seats, effectively.

Click to expand...

That must be one ugly looking aircraft!
Did it still have the split nose intake of the 545?

Re: 544, the RB.106 was offered so it could match the 545 if it was produced as a fighter and selected with the RB.106. It seems the M.O.S. added a few engine choices themselves to find the most sutiable engines. There is brief mention of the Avro 725 with a 'H.10' engine, I'm not sure what that was.

Re: Avro 725, the M.O.S. assessor of the designs (R.D. Projects) was worried that the new 725 front fuselage with side-by-side seating would need a lot of changes from the 720 and would require strengthening if it was to meet the same performance of the 720 airframe. They seemed quite concerned that most of these designs had high all-up weights and might have lacked structural strength. The weights I've quoted are the manufacturer's figures, but the M.O.S's estimates were higher in all cases.

Hood said:

There is brief mention of the Avro 725 with a 'H.10' engine, I'm not sure what that was.

Click to expand...

The designation suggests a de Havilland engine. Maybe a proposed engine that never got off the drawing board?

Here's a reduced detail copy of Barrie's drawing of the Type 554.

Hawker Hunter T.7 was the production version of the P.1101, the two-seat Hunter prototypes (2 built).

English Electric P.11 became the Lightning T.4.

I guess both were "winners" here.

PaulMM (Overscan) said:

Here's a reduced detail copy of Barrie's drawing of the Type 554.

Click to expand...

Nice find my dear Paul.

Thanks for sharing that drawing Paul.

I feel the decision to scrap OR.318 and develop the P.1101 and P.11 separately was the best way to approach things since the Hunter was more economical and the P.11 was fastest but chronically short-ranged and best suited for pilot conversion to that type. In the documents I've seen its odd that even though OR.318 was underway, it was recognised that trainer versions of these fighters might be needed anyway for Training Command other than whichever one selected to fulfil the OR.
The Air Ministry seemed to superficially understand the economic implications of a Mach 1.0 trainer.

I do not see any side of the application of the "Rule of area" in the model of the Avro 520/525 ...!

Hi All

OR.318 // NR/A.45 // T.147T