Air Starter Question

[robpar]

I was surfing the net the other day and found the Radial Rocket, what a cool plane. I was looking over the engine, a M14P and noticed that it used an air starter. What a good idea I thought. I have seen these used on very large diesel engines but not in an application such as this.

I think that originally the planes that these engines were installed in did not have an electrical system therefore the air starter. With modern planes relying more and more on electrical components it puts a large strain on the battery and electrical system. By taking the starter load off of the battery one could use true deep cycle batteries and have longer battery life and should the charging system fail in flight then deep cycle batteries can supply the buss load for a longer period than a standard battery that has to supply the start motor load.

True deep cycle batteries are available in the same case sizes as the current batteries. I have four similar sized batteries on my electric bike ( 12 VDC 20 Amp-hour x 4 = 48 VDC 20 Amp-hour) and they have been very dependable while going through many charge/discharge cycles.

Could an air start system be used on the Lycoming engines in the RV? Or could one be made? I would think that weight would be a wash one way or the other. The air receiver and valves would be about the same weight as the starter motor it replaces. If Li-Ion batteries are available they should weigh a little less than their Lead-Acid versions and have greater capacity.

Bob Parry

[81T]

You would get one, maybe two try's on a hot start and then you're done!

[andrew phillips]

what about the weight of the compressor, storage tanks, plumbing, valves etc. That has got to weigh more than an electric starter?

[Mike S]

Not all of the M-14 engines use air start.

A couple of planes here at O61 have air start M-14, and as was stated above, a couple of tries and then ???? Go look for someone with a full SCUBA bottle, or the equivalent.

One of our former residents had a Murphy Moose with the air start------ he was at another airport when he flooded the engine,ran the air down, and got a refill at the other airport-----suspicion is it was recharged with O2------anyway the backfire destroyed the air distributor on the engine, and burst stainless lines and fittings in the aircraft.

Milt, has an electric start, IIRC.

[SteinAir]

Most of the Vendeneyev M14 series that I know of do come from the factory with the air start, but Kimballs (I think) and maybe Culp have a kit which allows for an electric starter as well as adapters for standard AN fittings. The Air starting on those engines has been amazingly reliable...there were/are many, many thousands of them flying that way with no terrible effects. It apparently works decently, although most of the Pitt's 12 guys I know are adapating them to electric starters just to not have to deal with another system on the plane.

Milt & Dan H have more first hand experience here with that engine than I do (my round engine is a Pratt with a honkin huge electric stater), so they're in a better position to comment on it that I am....so would Keving/Jim Kimball.

Cheers,
Stein

[BikePilot]

I read somewhere that the air starter was origionally chosen because the M14P started out as a power unit to be used in extremely cold weather climates where batteries were not likely to work very well.

[dhall_polo]

I have some experience flying Nanchang CJ's and Yak 50/52 aircraft. Fun airplanes! M14's are very cheap and powerful engines, common in these aircraft.

The Nanchangs and Yaks rely on air systems for starting, brakes, flaps, and gear retraction. The systems feature redundant tanks, and most owners install a spare scuba tank for emergency recharging. Cost and simplicity drive engineering choices for the Russians, so obviously this worked well for maintaining a fleet of trainers for would-be Mig pilots.

My Range Rover, btw, also has air suspension. But it's very expensive to repair. The brits did not learn from the ruskies on that count.

[robpar]

I have some experience with pneumatic systems and they are quite dependable. They are subject to freezing, but the air brake systems in trucks seem to deal with this without too many problems. I do not know how much longer the air tank would last compared to a battery as installed in an RV. My guess is they would be comparable. The M14 engine is large around 620 cu. in and I think would need a bigger battery than is used to turn a 360 cu. in. Lycoming.

Using pneumatics for flap and gear retraction is interesting. Pneumatics are more difficult to position precisely than hydraulic or electric systems but an air-over hydraulic system would work well. But I think the best use of an air start system in an RV would be to unload the battery and allow longer lasting deep cycle batteries.

Bob Parry

[yakdriver]

I had a Nanchang CJ6 for 5 years and the pneumatic systems were very reliable IF you drained the moisture sump after every flight and gave it a small dose of air tool oil every once in a while. In almost 500 hrs of operation I never ran out of air on a cross country. Anything under 35 degrees or so the engine had to be pre heated or no way was it going to start. As for flaps they were either down or up no intermediate position. By the time you get all the components in there the air system is heavier than a battery/starter. Plus almost every airport has some way to deal with dead batteries. Heck you can get a 680 at almost any motorcycle shop. Don