In addition to the occasional scrutiny of model flying by Magistrates referred to in the section ‘Legal Controls over Model Flying’, Planning Authorities are constantly making decisions on whether to allow change of use for model flying sites or whether to issue clubs with a licence to fly on Local Authority land.
When they are taking these decisions they have a statutory duty to ensure that the activities on the site are not a potential nuisance to the surrounding area. When considering possible noise nuisance, the document to which they will most likely refer is the DoE Code of Practice.
If a noise complaint is made against your flying site, the Local Authority will probably send an Environmental Health Officer (EHO) to investigate. He will arrive armed with his noise meter and a copy of the DoE Code of Practice.
If the noise your models make is going to be judged by anyone, then the Code of Practice is most likely to be the standard that it will be judged against. For this reason alone, you should take careful note of the conditions laid out in this document; you never know when it may be applied to you.
Finally, the model flying knowledge of the EHO who may turn up will vary from nil to extremely good and, strange as this may seem, the same may apply to his knowledge of the Noise Code. Read and absorb the Code and it’s likely that you will know as much (or more) about it as he does, which would certainly be to your advantage.
The Code can be downloaded from:
6.2 BMFA Advice on the Noise Test
The noise testing procedure noted in the DoE noise code above should be followed carefully but to get the best results it is strongly recommended that you should take special note of the following.
Make sure that no noise reflecting surfaces are near the test site. This means not just buildings but cars, concrete, models, model boxes and even hard packed earth. Do the test over grass.
Do not take measurements when there is any appreciable background noise. Traffic on a nearby road, other models flying or being readied for flight and even people talking near the meter can affect the readings.
Wind blowing across the microphone has a big effect on readings. Do not test on breezy days and when you do test, use a microphone wind shield.
Make sure that the actual microphone is over the end of the seven metre tape, not your hand or the centre of the meter.
Think carefully about the four test positions of the model at the other end of the tape. As a suggestion, for the sideways-on readings put the fuselage on the seven metre mark, for the nose-on reading put the propeller over the mark and for the tail-on reading line the trailing edge of the wing up with it.
Please remember that large engines at full power can be very dangerous and before conducting any noise tests you are strongly advised to contact the Club Support Officer at BMFA Head Office for recommended procedures.
6.3 Helicopter Noise Testing
Because of the specific problems associated with performing noise tests on helicopters, it is recommended that a revised procedure be adopted.
Three markers should be laid out in a line on the flying area, one central, one seven metres to one side (crosswind) and one seven metres to the other side (crosswind). The helicopter which is being checked is held in a steady hover above the centre marker with the pilot standing downwind of it, as normal.
Noise readings are then taken with the meter positioned over each of the end markers in turn. For safety, when the meter is being carried from one end marker to the other, the checker must walk around behind the pilot flying the model.
The two readings obtained take the place of the four obtained in the fixed wing test and all other criteria are as noted in that test procedure.
Note – This method of testing is offered by the BMFA as a safe way of obtaining meaningful figures for helicopter noise levels on club sites by club flyers. It is not officially part of the DoE Noise Code.
6.4 Gas Turbines and Electric Models
The advent of model gas turbines and some higher powered electric models has presented an interesting problem in terms of noise levels and how they fit into the DoE Noise Code.
Although the gas turbine is, in scientific terms, an internal combustion engine, it is the BMFA’s contention that the DoE Noise Code should not apply to it. The reason for this is that the noise code was written to cover the types of model i/c engines that were known at the time, i.e. piston engines, and the concept of model gas turbines was not even considered.
The fact is that model gas turbines are very quiet indeed in the air when heard from any reasonable distance, far quieter than most piston engines, and on that evidence you would expect them to be able to pass 82 (d)BA at 7 metres.
However, most of the noise they emit is very high frequency and the higher the frequency of any noise, the better it dissipates with distance. Consequently the problem is that a very quiet gas turbine in the air will not pass the DoE i/c engine noise code on the ground because the test is done at 7 metres and the high frequency noise it emits has not yet had a chance to dissipate.
The Noise Code clearly does not apply to electric models as it is specifically for i/c powered models. Again most electric models are very quiet in the air and will cause no complaint
However there are certain turbine powered models and types of electric model that can sound very loud when in close proximity. EDF models and high speed pusher electrics can produce noise levels that can seem very loud at close quarters. Although there is no meaningful test that can be applied directly to such models, a subjective assessment can be made with a little common sense.
Given that the high frequency noise produced by such models does dissipate quickly with distance, the question has to be whether a model will cause a noise complaint and you cannot judge this from the flying field close to the flight path of the model. The only way to check is to go to a reasonable distance from the flying field and listen to model as a possible complainant would.
If a model is still considered to be too noisy for the field then it would not be unreasonable to ask the pilot to either modify the flight pattern or not to fly that particular model.
It should be noted that the BMFA have no record of any electric models causing direct noise complaints on flying fields, in clear contrast to i/c models.