[The following text should cover jet development activities in the SAE until Q1/43. My thanks to Brockpaine for an initial draft to guide me and get me started.]
History of South African turbojet development
During the late 1930s it becomes obvious the steep curve of technological development of common aircraft piston engines will reach a point where further increases in power output and economy will be too expensive in costs or engine size and weight. The fast development pace of the recent years will come to an end. Future high performance aircrafts thus require new technical, aerodynamic solutions and a new type of propulsion. In Europe development of such new propulsion was already under investigation, leading to some early designs and first successes for Whittle, Heinkel and others.
In the South African Empire it is General Peter Cooke-Botha of the Royal South African Airforce (RSAF) who becomes the driving force when his interest in jet propulsion is sparked after seeing reports of German and Italian jet flights in early 1939. At this time General Peter Cooke-Botha is a high-ranking member of the RSAF and serves as an overall organizer for the RSAF’s military development projects, allowing him to set up an initiative to create The Tegnologiese Navorsings Komitee (Technological Research Committee, TNK) in May 1939.
Once founded and funded, the TNK is responsible for selecting research and development projects, overseeing technological development of turbojets and other research-oriented projects in order to ensure the RSAF keeps up with the times. The Tegnologiese Navorsings Komitee receives a budget to award for R&D purposes and is composed partially by civilian aircraft experts, engineers, as well as ranking technically-oriented staff officers of the RSAF. General Peter Cooke-Botha himself leads the Tegnologiese Navorsings Komitee from 1939 to 1943. He is responsible for most of the initial military interest in turbojet design.
Looking for a lead scientist, a mutual friend introduces Peter Cooke-Botha to Dr. Nicolaas van Broom, a physicist interested in turbojet engines at the University of Johannesburg. Dr. Nicolaas van Broom who is a native of Cape Town became interested in flight physics in 1924 at age 23 and later achieved his doctorate in physics from the University of Johannesburg in 1934, with his doctoral thesis relating to thermodynamics and turbojet ideas. He stays at the University and becomes South Africa’s foremost expert on the turbojet engine, running a first small prototype turbojet in a work shop at the University of Johannesburg in 1937. After a series of personal meetings, Dr. Nicolaas van Broom accepts the role intended for him on July 22nd 1939. With the years to come a personal friendship between these two very different men grows and provides a common ground to drive South Africans jet development.
During the month August to October 1939 Cooke-Botha builds up the TNK, staffing the new organization and providing funds. He uses his contacts to the South African aircraft industry and industrial partners to initiate preliminary work for research and design projects to come. On November 14th the Tegnologiese Navorsings Komitee finally awards R&D money to create three research and design bureaus to concentrate on jet engine development.
• The van Broom Design Bureau is ordered to research centrifugal-flow turbojets. It is spearheaded by Dr. Nicolaas van Broom. Engine designs of this bureau are numbered in series, starting with VB.01.
• The EHR Design Bureau is ordered to research axial-flow turbojets and lead by Dr. Emil Harke-Rahn, an expert for turbo charger design who built up a research team at the University of Cape Town before. He gets into focus of General Cooke-Botha after publishing a dissertation on the potential of axial-flow turbojets. EHR engine designs are numbered in series, starting with EHR.01.
• Finally there is the Westhuizen Design Bureau. Eponym of the bureau is Curt Westhuizen, an engineer employed to head research on motorjet designs. Westhuizen engine designs are numbered in series, starting with W.01.
The TNK in turn administers the individual projects, assigning R&D money to individual design bureaus for the purpose of R&D and prototyping. The TNK ensures quality-control, shares relevant information between the three bureaus, and ensures the projects stay on task.
After build-up of a team and intensified basic research the van Broom Design Bureau begins work on the centrifugal VB.01 turbojet in May 1940. The engine is based on previous design experience and solutions proposed by Dr. van Broom, allowing him a jump-start on the other bureaus. Nevertheless, it lasts until December 1940 before the van Broom Design Bureau can offer a concept and design that satisfies the TNK. The team receives an R&D grant and is instructed to choose a manufacturing partner to build a prototype of the VB.01 turbojet engine. Dr. van Broom elects to partner with Rayton after LMF initially declines to build centrifugal engines. Rayton at this time is the leading manufacturer of radial aircraft engines.
In January 1941 the EHR Design Bureau presents initial plans for an axial-flow turbojet (EHR.01) to the Tegnologiese Navorsings Komitee. After a lengthy in-depth analysis and review of the proposed design, the TNK rejects the concept as unworkable on technical merits. The EHR team has to return to the drawing boards to design an enhanced EHR.02.
It is the Van Broom team that reaches the next milestone when on April 29th 1941 the VB.01 engine makes three successful test-runs, generating an initial thrust of up to 0,845kN (190 lbf). Pushed by their success the team continues to improve on their design until on May 18th the VB.01 engine is operated for observation by members of the Tegnologiese Navorsings Komitee. During the test the engine suffers runaway combustion and reaches 2,67kN (600 lbf) of thrust, twice the thrust of any previous test. A technician manages to shut down the engine without damage, and the TNK observers do not even notice that the engine malfunctioned. After the review a detailed analysis of the test reveals some short comings of the design and it takes a month before on June 24 the VB.01 engine reaches 2,67kN (600 lbf) in normal operation.
In August 1941 the Tegnologiese Navorsings Komitee approves continued design work on both the EHR.02 axial turbojet and the VB.01 centrifugal turbojet. The Van Broom Design Bureau receives funding to construct two more VB.01 engines for (destructive) endurance testing while a forth should be prepared for in-flight testing. The bureau is also ordered to select a partner to design an airframe for flight trials by 1943.
September 16th 1941 brings some important news. Foller & Sons Metal Works, as part of its bid to design the first South African jet aircraft, buys out one of its suppliers, Blomkamp Aviation, and orders the Blompkamp factory and staff to begin preparing for jet design work. Blomkamp’s factory is small but technologically advanced, and has an easily-secured adjoining airfield suitable for testing prototypes. The Blomkamp factory is additionally valuable as it is less than half a kilometre from the workshop of the Van Broom Design Bureau. Leading engineer is Johan Blomkamp, an aircraft designer and entrepreneur. Blomkamp and his four brothers start Blomkamp Aviation in 1932, producing parts for deBroek and Foller. Although they design one civilian aircraft in 1936, it does not reach production.
The Westhuizen Design Bureau presents their motorjet design W.01 to the Tegnologiese Navorsings Komitee on October 19th. During the review Curt Westhuizen, the project leader, requests to design an axial turbojet instead of a motorjet but is rejected by the TNK, which orders him to continue working on motorjets. Westhuizen and his team return in frustration as he reveals in his autobiography 20 years later.
Following TNK decision in August van Broom determines in November 1941 to partner with Foller & Sons Metal Works to build the first South African jet, with Johan Blomkamp and his R&D staff to take priority. The team at Blomkamp has difficulty sizing his aircraft design for the engine as many engine specifications are not yet fixed and many ancillary units hardly exist as prototypes. The team eventually designs a small all-metal single-seat airframe internally dubbed Design 089 but construction of the test bed aircraft at the former Blomkamp Aircraft factory does not start earlier than May 1942.
Meanwhile the EHR Design Bureau is taking steps to enhance their design. Modifications to the compressor and combustion chamber lead to a completely new approach, with some success. During a new review at the TNK on December 9th 1941 EHR is finally ordered to select a partner to build the first EHR.02 for test purposes based on the new concept. Using the connections of General Peter Cooke-Botha EHR arranges a partnership with the Lüderitz Motor Factory (LMF), but the partnership soon is fraught with interpersonal difficulties between Dr. Emil Harke-Rahn and Gerbrand Bakker who is head of the R&D and prototyping department at LMF. The partnership between EHR Design Bureau and LMF finally becomes seriously strained when the construction of the first EHR.02 engine is found to be badly flawed. In the attempted first run of the engine on August 2nd, the EHR.02 is unable to maintain combustion. An analysis reveals bad workmanship and use of unsuited material. As a result the Tegnologiese Navorsings Komitee orders LMF to rebuild the engine to the original specs of the EHR team at their own expense.
August 24th 1942 marks a cornerstone for South African jet development as Blomkamp rolls out the first of four Design 089 test bed aircraft. The aircraft is officially named the XFJ-1 and is about to become the Empire’s first jet powered aircraft. The VB.01, however, is not yet ready for installation and so Pieter Mynhardt, Foller’s chief test-pilot, flies the XFJ-1 in unpowered trials with the plane being towed by a Foller FD-4 Mk II. The XFJ-1 briefly lifts off the runway for an unofficial first flight on September 18th. Tests with the still-engineless FXJ-1, the plane proving relatively easy to handle with gentle stall characteristics and moderate control forces, continue successfully until October 19th when the forth VB.01 engine is finally ready for installation and placed in the airframe. Ground tests are executed until on October 25th a test-run of the XFJ-1 plus VB.01 engine nearly turns out disastrous when the engine ingests a screwdriver and a pile of grease-soaked rags, immediately catching fire. Although the fire is quickly extinguished, the VB.01 engine is pronounced too damaged to continue testing, and the XFJ-1 airframe requires two months of repairs. As VB.01 engines No. 2 and 3 are being used for destructive endurance testing, and No.1 is a knocked up prototype, they are not available for installation and the test program stalls. To solve the issue van Broom orders another VB.01 engine manufactured by Rayton as soon as October 31st. The engine is built to a lightly-modified design dubbed the VB.01a.
In order to achieve a thrust level suitable for combat aircraft and with results from sustained testing of the VB.01 engines Dr. van Broom begins to design a larger centrifugal turbojet intended to exceed 6,67kN (1,500 lbf)in November 1942. This engine is designated the VB.02 and represents a scaled-up VB.01. Soon, on December 30th 1942, engineers at Walter are requested by the TNK to design a mixed-power aircraft based around the probable dimensions of the VB.02 engine. Van Broom is not enthused about having to work with Walter, as he has so far had an excellent working relationship with Foller/Blomkamp. He tries to intervene but General Cooke-Botha is bound by political decisions. The new Walter project is dubbed Design 091.
Until early January 1943 LMF has completely rebuild the EHR.02 and the all-new engine makes a successful first run on the 14th, generating 1,57kN (350 lbf) of thrust. While the thrust generated is not impressive compared to the VB.01, the test is a proof of concept and encourages the EHR bureau to continue. However, Dr. Harke-Rahn and his team are still several steps behind van Broom because only two days later a VB.01a engine is ready for use and installed in the repaired XFJ-1 airframe and test runs are scheduled for the start of February. Those tests are very carefully prepared to ensure success. After almost three weeks of preparations the XFJ-1 operates its engine statically for nearly an hour on 4th of February. Taxi trials are rescheduled due to rain and consistent overcast, the crew around Foller test pilot Pieter Mynhardt and RSAF test pilot Capt. Julius Klaast not willing to accept the slightest risk. Three days later weather forecast is good and the XFJ-1 rolled out her hangar early in the morning. During one of the tests later that day the XFJ-1 is at 55 knots with Pieter Mynhardt at the controls when a tire bursts and the plane swerves off the runway onto the grass. Mynhardt manages to keep control and the aircraft is not significantly damaged but returns to the hanger for minor repairs and final evaluations.
On February 14th the RSAF is catapulted into the jet age when the XFJ-1 flies for the first time with Pieter Mynhardt at the controls. Mynhardt pilots the XFJ-1 to an altitude of twelve meters then lands the plane again. Two similar flights take place later in the day, one with Klaast and one more with Mynhardt at the controls. A fourth flight, intended to circle the airfield with gear remaining down, is cancelled due to rising winds.
Pieter Mynhardt - now the first South African jet pilot - is a veteran of the South American War. He retired with seven combat kills and returned to university to study aeronautics. Upon graduating he was hired by Foller as test pilot. Due to his extraordinary skills and technical background he is soon given more responsibility and so he becomes Foller’s chief test pilot. It is his mix of both aeronautical engineering training and extensive flying experience that makes him one of the most valuable contributors to early SAE jet development.
The 15th of February does not see any new flight tests due to bad weather. Instead the time is used for minor repairs, extended checks and paper work. The next day weather is good enough again and after some taxi trials Mynhardt takes the XFJ-1 up for her first two circuits around the airfield. Captain Klaast follows in the evening, staying in the air for almost half an hour and retracting the landing gear the first time. On the 19th it is Mynhardt again who flies the XFJ-1 for an official party from the RSAF and the Tegnologiese Navorsings Komitee including General Cooke-Botha who is very pleased with the results although Pieter Mynhardt is half-hearted chastised for exceeding his mission profile by making an unplanned climbing roll during the demonstration. Flight tests are ordered to be pushed, the second prototype to be readied by Foller-Blomkamp at highest priority. Hence the manufacturing team at Blomkamp is enlarged and work proceeds in two shifts until the second XFJ-1 test bed, with RSAF pilot Capt. Julius Klaast at the controls, becomes airborne at Blomkamp’s airfield by March 29, enabling the test teams to set up an extended test program.
Quoted
Originally posted by Brockpaine
Thursday, April 25th 2024, 11:28pm
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