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Loud DLE petrol engine

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Timothy Harris 117/07/2017 11:35:23
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384 forum posts
58 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
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6890 forum posts
170 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
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384 forum posts
58 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 Harper - Laser Engines17/07/2017 13:45:24
2649 forum posts
123 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
973 forum posts
31 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
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384 forum posts
58 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
973 forum posts
31 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 Harper - Laser Engines17/07/2017 16:48:15
2649 forum posts
123 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
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2528 forum posts
445 photos

Noisy engines will lose us our fields.

Why don't more people understand this?

maurice northcott17/07/2017 18:10:49
65 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
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2285 forum posts
9 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
973 forum posts
31 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.

Rich218/07/2017 05:57:06
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2201 forum posts
742 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.

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