I was fortunate to obtain a 10501 directly from Nimrod XV244. Thanks to the team at Morayvia for finding the time to remove it, an ideal unit for starting the Spey250.
I have been very fortunate to have sourced a Rover APU from a Nimrod, unfortunately it was still inside XV244, a Nimrod owned by the Charity Morayvia.
Luckily I had two helpful chaps, both involved in the Morayvia project and experienced in the Nimrod Aircraft that were prepared to remove it, no mean feat I believe. Thank you to Shuggie & Chris for taking the time!
A picture of Shuggie inside the engine bay of XV244.
This is the actual APU mounted in the tail section of Nimrod XV244. All the pipe work and electronic connections will have to be disconnected and moved to one side to allow the safe removal of the engine.
The APU is housed inside a titanium box, I presume it’s there to act as fire protection. This box has to be disassembled to facilitate the APU’s exit from the aircraft.
A close up of the accessory’s.
Removal sling attached, ready to be lowered to the ground.
Shuggie is in the tail section about to lower the APU to the ground.
I expect it’s the first time in a while that the APU has seen daylight.
Safe on the ground, Shuggie , Chris and Rover 2S, mission completed!
Reassembled on the ground.
Plastic bags added to help prevent FOD, also a nice view of the air producing compressor.
Now after a couple of days in transport, the 10501 is now at mission control in Shropshire. Pictured is the Air Producing Compressor.
A close up of the Centrifugal Compressor Inlet, I might be wrong but I understand the compressor wheel to be the same as the Compressor in the Rover 1S60 unit.
PT over speed amplifier can be seen lower left.
Care must be taken to prevent over speeding the PT Compressor as catastrophic failure will occur should there be no load on the air outlet or the Compressor is in a stalled state, an anti surge valve prevents this from happening and works in harmony with the Spey’s ADV.
Not a lot going on in this view.
Connections for EGT, a missing Hour Clock?
The blue plastic bags are protecting the oil inlet and outlet pipes, the oil filter assy can be seen at the top of the accessory cluster.
Another side view.
APU Exhaust designed to interface with the Nimrod’s Airframe.
Now were getting to the tricky part, the air pipe work itself. I always try to make the engine frames as compact as possible, not entirely sure what I am going to do, but I do think the pipe work is taking up a bit to much space, modifications to it might be in order.
The pipe work includes a one way valve and a pressure reducing fitting. The Anti Surge Valve is fitted below this pipe work just below the elbow, hence it is not currently fitted, more modifications I feel.
Temporary engine frame supports, I’m going to make this frame a little more substantial, it will do for the moment though.
Time to start on the control panel.
The original Nimrod Control Panel had an EGT and Oil Temp Indicator, I am modifying the unit to have a few more additional non standard indicators, from the left, Gas Producer RPM, Power turbine RPM, EGT, Oil PSI and Oil Temp.
The inside of the control panel so far, a few Timer Relays etc to added and of course a load of wiring.
And here is the load of wiring and it was fun making it to.
Time to make the running stand. A lot of things have to be considered, especially being able to allow for thermal expansion of the engine in all directions whilst running and sat in the frame, for this one fixed and three pivot supports will be used, two facing sideways and one facing forwards.
The only fixed support can be seen in this photo.
I try to make the frames so that the engine is totally encased, thus if it comes in to contact with an object the frame takes the knock, not the engine.
Whilst I was making the frame I decided to remove the air intake housing, as the engine is no longer attached to an airframe it was pointless keeping it on, it was a bit of a pain to remove though.
The electrical control panel on the engine side of the wiring loom, quite a lot will have to fit in here, I have possibly fitted to small a box, we shall see.
I wanted to add an RPM Indicator to the Gas Generator electronically, thus I needed to find a suitable pulse output for the probe which would be needed for generating the signal, the oil pump seemed the only choice.
Blanking plate removed and inside the shaft was a fine threaded hole, no gear of spline to take a pulse from, but otherwise a good start.
I purchased a few small gears that could be adapted to fit the shaft, the one chosen is from the drive gear of a mini-moto bike.
The thread was cut off and then faced, a hole drilled in the center so that the gear can be bolted to the shaft.
A spacer was made to be a tight fit inside the opening to the shaft and a new outer aluminium cover was machined to accommodate all of the above.
New pulse gear fitted.
A hole was drilled and tapped so that a reluctance probe could be fitted and set at about 0.5mm away from the tips of the gear.
Ian kindly made me one of his Tacho Driver boards, a dual board modification as it would also drive the Gas Generator as well as the Power Turbine Gauges.
Driver board, relays and all the wiring installed in to the control/ termination box on the engine.
The Starter Cut Out, Resistance Coil and Starter Solenoid all wired in ready for use.
I have also added an Oil Pressure Sender to the system in addition to the low oil pressure switch, just for piece of mind.
Custom designed oil tank fitted with a heafty K&N Breather Filter which is attached to the top.
A picture showing the oil pipe work, just out of view is the oil temperature probe, fitted in to the bottom right corner of the oil tank.
Making use of various flanges and adapters an outlet pipe work arrangement has been made for the Compressor Scroll. When running the engine an Anti Surge Valve is required when initially starting the engine and this closes as the main outlet valve simultaneously opens during the main engine start sequence, this is a significantly smaller arrangement than would have originally been used in the Nimrod.
Still only tack welded for setting up purposes, but looks good and all the parts fit without fouling.
Anti Surge Valve (NO) top and Main Delivery Valve (NC) bottom. Both Valves connect to the termination box using quick release electrical connectors as the whole assembly will be removed when not in use.
Air intake bell mouth for the air compressor.