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RCGF Stinger 20cc


cymaz
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I thought I’d post my experiences on the new range of petrol engines that RCGF have recently produced. 

 

My 20cc Stinger engine came from Morris Mini Motors. The engine looked to be nicely machined with good fitting gaskets. All the bolts were good and tight. The engine is a beam mount. The glass filled nylon mount has the same firewall bolt pattern as a DLE 30. I didn’t use any of the supplied bolts as I use Modelfixings bolts and had just recently bought some for this very engine. 

 

The spark  plug is a glow size. Bear in mind they cost a few ££ more than a CM6. There a a few posts on RCUniverse that mention that the supplied plug can break if you a too rough in pushing it on. Also that the plug comes away from the threads in the head. I’ve not encountered any such problems. The cap is a good solid fit ( but due care is need to put the cap on directly over the plug). The ignition box is very slim with a good amount of HT lead.

 

The manual is very good with all the relevant info. It also has all the engine dimensions and firewall measurements and templates, very handy. 

 

I’ve tried both a wood 16x8 and a 17x6. The initial needle settings were done as per manual. After the initial 20 minutes of ground run as recommended by the manual, I got a solid reliable idle of 1750 ( using the 17x6), snappy and instantaneous pick up and plenty of pull at WOT. Quickly shutting the throttle and the motor settles well into the solid idle once more.

 

There is no evidence of leaks ( oil or otherwise). On my exhaust outlet ,( you can’t call it a muffler at all), I put 6” of high temp silicone tubing. This has some dampening effect on the sharp “bark” of the exhaust note.. I did put a pepper pot restrictor on it but this sent the engine into poor tuning. Maybe there is too much back pressure or the engine needs a lot more running in. The manual states that the engine is properly run in after 2 gallons.....that’s a looong time in the air.

 

With the engine only ground run at the moment, it’s hardly a thorough work out, but so far so good.

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Yes, it’s 84dB @ 7 meters. The silicone tubing helps a lot without restrictions.  When I’ve done the noise test, of course I’ll report the results. 

The club has two noise meters, I’ve got one and can do engine tests......I’ve even been known to fail my own engines!!

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On 13/05/2022 at 06:04, Graeme White said:

Do you have noise restrictions at your club? Any plans around quietening it down an do you have a db meter?

 

Did the noise test yesterday...

  • 32:1 fuel mix
  • Aerostar  17x6 Wood prop
  • Engine fully cowled
  • exhaust downpipe fitted with 16mm ID / 22mm OD high temp silicone tubing 
  • large pepperpot muffler fitted to silicone tube

The engine was allowed to warm up. The plane was down wind 7 m away held at waist height, at full throttle, exhaust side was 84dB, cowled side was 83dB. Club limit is 84dB, so it passed but only on that prop as it was at the maximum allowed.

 

Hope this helps

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