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Loud DLE petrol engine

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Timothy Harris 117/07/2017 11:35:23
695 forum posts
102 photos

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 ?

Martin Harris17/07/2017 13:05:54
7564 forum posts
188 photos

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...

Timothy Harris 117/07/2017 13:27:10
695 forum posts
102 photos

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!

Jon - Laser Engines17/07/2017 13:45:24
3764 forum posts
147 photos

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.

ChrisB17/07/2017 14:19:44
1191 forum posts
34 photos
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

Timothy Harris 117/07/2017 15:02:41
695 forum posts
102 photos

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 😊.

ChrisB17/07/2017 15:46:55
1191 forum posts
34 photos
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.
Jon - Laser Engines17/07/2017 16:48:15
3764 forum posts
147 photos

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

David Davis17/07/2017 17:45:41
2887 forum posts
489 photos

Noisy engines will lose us our fields.

Why don't more people understand this?

maurice northcott17/07/2017 18:10:49
75 forum posts
59 photos

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

Tom Sharp 217/07/2017 18:52:05
2862 forum posts
16 photos

I have a couple of DLE engines, they are very noisy with the supplied silencers. As some one above said, they would be better supplied without.

The trouble is many people would be put off buying an engine lacking a silencer, so supplying an engine with a throwaway silencer is the best of a bad job.

ChrisB17/07/2017 20:40:13
1191 forum posts
34 photos

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.

Rich too18/07/2017 05:57:06
2619 forum posts
1011 photos

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.

Ron Gray06/08/2017 09:56:38
849 forum posts
213 photos

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!

David Davis06/08/2017 10:23:52
2887 forum posts
489 photos

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.

Steve Balaam06/08/2017 10:44:21
68 forum posts

I have a DLE 30 and replaced the silencer with a Just Engines Duo compact quiet silencer

Made a big difference.

Paul Marsh06/08/2017 10:46:08
3239 forum posts
893 photos

I have a DLE 20 and 40cc twin. Using a proper silencer is quiet, but the included one is not really a silencer.

john stones 106/08/2017 10:59:47
9365 forum posts
1428 photos

No argument here, supplied silencer doesn't, you have to spend money.

Denis Watkins06/08/2017 11:06:47
2721 forum posts
137 photos

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.

Ron Gray06/08/2017 12:51:57
849 forum posts
213 photos

I believe that both JEN and Weston provide that!

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