I use a small spray compressor ( off eBay ) for my oscillators & Stuart models plus a Clarke Ranger with a 24 litre tank for general use, noisy ( uses the volume up at a steady rate ) but does the job. I would like a 'silent compressor' 'Clarke or Bambi' but too expensive for me. I know of members who have built their own silent ones from refrigerator compressors but it's the purging & & safe disposal of the refrigerant gas ( CFC's ). Usual disclaimer applies.

George.

the refrigerant is already exhausted when it's removed from fridges so the compressors is ok to use, new ones has not been gassed yet.I run four of them into a common receiver very quiet can hardly hear them

I use pneumatic push in fittings from eBay ; Just type in pneumatic push in fittings in the address box & it brings up pages full of fittings. I can't seem to link it at the mo' ?. I use the 6mm OD x 4mm ID nylon tubing size from the compressor regulators via the tubing to the model inlet branch, usually just pushed on a brass tube at the inlet manifold.

George.

Has anyone made a unit from a automotive aircon compressor and an electric motor ? I know here in Australia you could buy a compressor unit to pump up the tyres of a 4WD. It consisted of a small two stroke motor and a modified aircon pump off a car – the modifications were mainly for lubrication of the pump . If run from an electric motor it would be almost silent .

Just a thought .

Ian.

I've posted this before, but it shows an engine with a moderate swept volume (7/8" bore x 3" stroke) running from a 12V tyre inflator. The battery has since given up the ghost, but Lidl's handheld cordless compressor gives the same result.

**LINK**

I put a 5/16" thread on the inlet pipes for all my models so that tyre pumps will fit. The noise is enough to make the grandchildren jump.

Edited By Mick B1 on 26/01/2019 09:23:30

That's right, but you can shift the output towards high-volume low-pressure by adding a reservoir between the pump and the model engine.

With a foot-pump, an ordinary 2L fizzy drinks bottle will do – there's no danger of anything nasty happening because the human is in control. OK for a quick check, but working a foot-pump soon gets tired.

A motorised pump with a reservoir is more convenient and less safe; it needs to turn off automatically when the reservoir is at max operating pressure, and back on again when the pressure drops. Additionally, there needs to be a regulator between the reservoir and engine, and a couple of pressure gauges and a throttle would be nice too. The reservoir has to be suitably strong with a drain-cock and reliable safety valve,

A quiet affordable pump well suited for supplying air to model engines doesn't seem to be on the market. It may be because most domestic requirements for low-pressure high-volume air are met by fans. For this purpose fans aren't much use because they churn inefficiently at engine pressures.

Instead people adapt things like air-brushes and a variety of less suitable pumps. Given the need and the fact we all have machine tools, it's odd that no-one has designed an engine compressor yet – or have they? It would make an interesting project!

Dave

Edited By SillyOldDuffer on 26/01/2019 09:57:27

A pump type available here in NZ quite cheap is for inflating air beds, this would probably be ok on very small motors. For small motors I have a small medical type diaphram compressor capable of 30 psi, but to just test the motor to see if it works I just connect it to a 5L garden spray pump(armstrong power).

Ian S C