Tim Flyer Posted July 17, 2017 Share Posted July 17, 2017 I cannot believe how loud some makes of the 2 stroke petrol engines are. Yesterday a member brought a new model powered by a DLE 55 single cylinder 2 stroke to the club. Luckily we do not have any noise restrictions at our site but just use common sense. He was running the engine with the stock supplied muffler. Whilst the engine and plane looked good the noise was unbelievable. It totally drowned out my OS55 running on full power with a Weston tuned pipe. It's a shame manufacturers make engines like that for our market. I am surprised that they don't supply ear defenders with this DLE motor. Other petrol engines we regularly see at the club such as the OS GTs are whisper quiet in comparison. We have also seen sheared prop bolts a few times on DLEs. I would wonder whether there is a design / quality issue on some ? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 17, 2017 Share Posted July 17, 2017 I do think that the sound generated by the average petrol 2 stroke spoils a nice scale model. I was very aware of this at Cosford yesterday - the multi-cylinder 4 strokes in their dedicated slot were a delight to listen to compared with the rather harsh crackle of many of the 2 stroke warbirds. However, it's not as simple as 2 stroke versus 4 stroke. I have a Mahers Pacer powered by a Zenoah 38. I can't claim any credit as it was given to me (I managed to make a small donation to the previous owner) and built by someone else. They made a silencer (internal baffling details unknown) from a die cast project box which completely removed any harshness and imparts a rather melodious and appropriate note to the exhaust sound which is often commented on. I'm sure that any manufacturer could design a similar system at little additional cost should there be sufficient demand... Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted July 17, 2017 Author Share Posted July 17, 2017 Agreed Martin . I think scale are way better with 4s. Yesterday one member had a nice YS nitro four stroke that made a lovely sound and was powerful and yet quiet in his aerobatic machine. The OS petrol motors seem relatively quiet too in stock form. The 4s Lasers sound great too, but this awful DLE engine was very loud even on half throttle. It sounded like one of those unbaffled mopeds or a chain saw so anyone else flying at the same time couldn't hear their engines! Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 17, 2017 Share Posted July 17, 2017 We had a similar experience with a dle55 and indeed it could be heard over 2 miles away by a 90 year old club member! needless to say we had to bring it down some and asked the owner to fit a half decent exhaust. Part of the issue is the fact that the exhausts are made of material that is wafer thin. Im pretty sure a coke can uses thicker metal than some i have seen. Quote Link to comment Share on other sites More sharing options...
ChrisB Posted July 17, 2017 Share Posted July 17, 2017 3 things spring to mind. Prop size and make/type, exhaust and throttle control.If you run a slightly bigger prop, either wooden or carbon the engine will rev lower and the tone will be better. The corned beef tins they supply should be thrown away as soon as you open the box and replace with an aftermarket unit or home made and include stingers. Also, as with most models they are overpowered therefore rather than using the throttle as a switch use it as much as other controls and if you can use different parts of the sky therefore reducing the noise impact. One solution is to make your own silencer. A header box running to a pipe or firewall box with baffles and twin outlets. You can also line the cowl with heat resistant foam to help deaden the noise. With many clubs its not the actual DB that's the issue, its the tone that makes a model sound loud.Edited By ChrisB on 17/07/2017 14:21:25 Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted July 17, 2017 Author Share Posted July 17, 2017 Interesting to hear that the DLE silencers are so bad Jon and Chris . It certainly wasn't prop noise or vibration. When I first heard it in the air I thought the manifold had detached! The rpm he was doing were not that high either as he was running in ...Half throttle was awful! This was this fellows brand new model so he didn't realise he should throw away the one supplied. To be fair I do think it rather poor than a manufacturer supplies such an inefficient muffler. Anyway I certainly won't buy a DLE as I love the Laser engine sound performance on my models and I also happily run a number of OS engines that are way friendlier than that loud DLE thing 😊. Quote Link to comment Share on other sites More sharing options...
ChrisB Posted July 17, 2017 Share Posted July 17, 2017 The engines are made in the far east where things such as noise, health and safety and planning/environmental health issues are less stringent. Personally I'd rather they didn't include a 'silencer' and leave it to the buyers to source their own. Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 17, 2017 Share Posted July 17, 2017 I agree with the comments about props. Some are really flippin loud but folk use them as they sound more powerful. Im a fan of wooden props as im too cheap to buy carbon Quote Link to comment Share on other sites More sharing options...
David Davis Posted July 17, 2017 Share Posted July 17, 2017 Noisy engines will lose us our fields. Why don't more people understand this? Quote Link to comment Share on other sites More sharing options...
maurice northcott Posted July 17, 2017 Share Posted July 17, 2017 In our Club, we call the standard box mounted to the side of any DLE a "Noise Diverter" for the simple reason that that is all they do. All DLE-users in our Club have fitted reasonable mufflers or inserted the "pepperbox" type of noise reducers and much experimentation is done with props. Edited By maurice northcott on 17/07/2017 18:12:31 Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 17, 2017 Share Posted July 17, 2017 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
ChrisB Posted July 17, 2017 Share Posted July 17, 2017 I've got a DLE 20 in a WOT4 XL. I bought a Pitts wrap around silencer for it. Yes it cost £40 but so what, better than using the supplied tin can. Even with the after market silencer its still a bit tinny. I will at some point put a stinger in it. Quote Link to comment Share on other sites More sharing options...
Rich too Posted July 18, 2017 Share Posted July 18, 2017 I agree, dle should supply them without and it would stop the negative bashing of a cracking motor. A lot of people fit alternative pipes and cans and so I think it is just a cheap fix for others. My dle 55 has a pipe fitted and sounds and runs great. Btw it is not the dle that is noisy it is the exhaust. Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted August 6, 2017 Share Posted August 6, 2017 Totally agree with comments above. the DLE is an excellent engine, let down by a cheap exhaust, hence why they are, initially, good value for money. I have 4 of them from the 30 up to the 55 and all have the same loud, harsh exhaust note with the standard exhaust amplifier. Change them for canisters or aftermarket boxes (Pitts etc) or even just pepper pot baffles and the noise is transformed, softer and much easier on the ears! I also have an NGH 38FS and was surprised at how noisy that was despite it being a FS so have fitted a JEN baffled silencer which has substantially changed both the volume and pitch of the exhaust note. Moral of the story, as I see it, 'yer pays yer money and makes yer choice'. In other words going for a more 'upmarket' engine, DA, OS etc may actually prove to be a cheaper long term solution. Or, as I'm doing, invest in a Laser! Quote Link to comment Share on other sites More sharing options...
David Davis Posted August 6, 2017 Share Posted August 6, 2017 A friend once flew a 1/4 scale Fokker DVII powered by a Zenoah 38. He had made up some sort of manifold then took the exhaust though the firewall to an empty Camping Gaz cylinder housed just behind the engine. An outlet pipe from the cylinder was arranged to go through the side of the fuselage. Not very scale-like perhaps but effective. Quote Link to comment Share on other sites More sharing options...
Steve Balaam Posted August 6, 2017 Share Posted August 6, 2017 I have a DLE 30 and replaced the silencer with a Just Engines Duo compact quiet silencer Made a big difference. Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted August 6, 2017 Share Posted August 6, 2017 I have a DLE 20 and 40cc twin. Using a proper silencer is quiet, but the included one is not really a silencer. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted August 6, 2017 Share Posted August 6, 2017 No argument here, supplied silencer doesn't, you have to spend money. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted August 6, 2017 Share Posted August 6, 2017 All true, a good silencer costs as much, or more than a petrol motor There is an opening here, and room for a cottage industry, amounting to a individual making good living, providing well priced silencers. Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted August 6, 2017 Share Posted August 6, 2017 I believe that both JEN and Weston provide that! Quote Link to comment Share on other sites More sharing options...
TartanMac Posted August 6, 2017 Share Posted August 6, 2017 I don't have a DLE but have heard a few with std mufflers they sound awful. I used to work with chainsaws every day 50cc around 80cc and 120cc they all sound way better than a DLE muffler. They had a very thin gauge sheet steel pressed box shape muffler they were alot quieter and a better sound than a std DLE muffler. I suppose it would be heavier than the DLE std alloy muffler and maybe more expensive to produce. I have a Moki 30cc petrol with a similar rubbish muffler I will be going to Weston UK for one of there mini pipes Quote Link to comment Share on other sites More sharing options...
BackinBlack Posted August 6, 2017 Share Posted August 6, 2017 In my view the fault here lies with the importers/resellers. They must have some contact with the original manufacturers, is it beyond their wit to specify that either the engines have an adequate silencer or supply without silencer. We have many BS and EU standards which require imported products to conform, even if they qualify as component parts, not finished products, why are these imports treated differently to our home market produced items? Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted August 6, 2017 Share Posted August 6, 2017 I hope you club didn't let him fly it ? You may find you have a noise limit sooner than you think . The stock mufflers are not fit for purpose and should be binned. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted August 6, 2017 Share Posted August 6, 2017 We've had noise issues in the past from glow 2 strokes, so it aint nowt new, nor particular to Chinese engines. Quote Link to comment Share on other sites More sharing options...
Former Member Posted August 6, 2017 Share Posted August 6, 2017 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
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