Why we need sirens, hooters...

[Old Koreelah]

This tragedy shows that our planes need a lightweight, loud warning device.

 

Two killed in Portugal beach plane crash - BBC News

 

I've been trying to design a large pop-out whistle that could use airflow to make a racket.

 

 

[IBob]

This tragedy shows that our planes need a lightweight, loud warning device.Two killed in Portugal beach plane crash - BBC News

 

I've been trying to design a large pop-out whistle that could use airflow to make a racket.

There used to be a party toy...a little tube with a rotor in the centre mounted to a flat plate with holes. You blew in it and it made a loud wheeee noise.

 

I thought about making bigger strap-em-to-your-leg ones for skydiving, but never got round to it. Mercifully........

 

Something sounding like a car/truck horn would probably be better, in my view: most people automatically associate that sound with 'vehicle coming, get out the way' whereas I think the response to a whistle (or wheee) may be much slower.

 

 

[Oscar]

Some sort of mechanical warning device would be useful, though nowadays, given that people appear to not be able to walk without being on their mobile phone and very, very obviously can't walk and talk at the same time, maybe what is needed is an electronic 'screecher' on the mobile phone frequency that imitates a police siren. I'd like it to be a personal device, so I can use it to make my way through shopping malls...

 

 

[old man emu]

Junkers used to make a quite effective wind driven siren. The Jericho Trumpet.

 

https://www.youtube.com/watch?v=LCB8ZVxKqyI

 

 

[onetrack]

Isn't the main problem, with fitting a horn or warning device to an aircraft, the problem of projecting the noise forward?

 

All horns and sirens have a funnel shape body facing the direction to which the sound is required to travel.

 

Fitting a forward-facing funnel-shaped device to an aircraft is going to play havoc with airflow in the area where it's fitted.

 

I guess you could face a simple vehicle-type horn or siren at 90 degrees to the direction of travel, and a fair percentage of the warning sound would still reach the intended area. However, even this arrangement is going to disrupt airflow over the area where it's placed.

 

 

[onetrack]

Unfortunately, the Jericho Trumpet of the Stuka was 2.3' (0.7M) in diameter, and took 20-25kmh off the aircrafts performance because of the massive aerodynamic drag!

 

I don't think anyone with a light aircraft is prepared to lose a sizeable percentage of performance, due to a warning device for people on the ground, that might only be used once or twice in the life of the aircraft!

 

 

[Old Koreelah]

If the engines has stopped the last thing you need is extra drag; that's why I'm trying to design a whistle/siren that can be popped out at the last minute and makes enough noise to be heard by anyone on a beach, golf course, etc. up ahead.

 

Yonks ago I researched extra horns for my bike and couldn't find anything lighter than a kg or more.

 

Aircraft designers' maxim: add lightness

 

 

[hihosland]

Car horn or siren type sounds are a must for warnings.

 

I ride on cycle paths and often come across pedestrians/dog walkers with ear buds in.

 

I find that any electronic beep type sound, If they are registered at all, are ignored.

 

 

[onetrack]

Well, the problem is - around 50% of males over 60 have lost a sizeable percentage of their hearing.

 

I've lost 70% of my hearing, and I can assure you, I can't hear bicycle bells on bikepaths and footpaths - even with the best hearing aids.

 

But you always get the hardcore lycra set doing 70kmh on shared paths, ringing their bell and expecting you to jump out of the way.

 

I can hear low-pitched sounds, but any high-pitched sounds are non-existent to me.

 

I have trouble with womens voices due to their high pitch, but I rarely have a problem with blokes voices. This can be a blessing, when being nagged.

 

Indigenes have a very high level of hearing loss, too, largely due to ear infections. That's largely the reason they yell at each other, much more than whites do.

 

Any effective warning sound has to have several pitch ranges in it - and if you've noticed in recent times, the emergency services now have warning sounds that are not just a regular siren sound, but they also have a range of additional sounds comprising low tones as well as high tones.

 

The emergency services have problems with vehicle drivers with their sound systems turned up - but they have realised a deep pitch tone has a higher penetration ability than a high pitched one.

 

 

[Old Koreelah]

Car horn or siren type sounds are a must for warnings.I ride on cycle paths and often come across pedestrians/dog walkers with ear buds in.

I find that any electronic beep type sound, If they are registered at all, are ignored.

My favourite bicycle shop has provided quite a few bits for my plane, but when I tried some electron bicycle warning devices I was underwhelmed. They're barely audible twenty metres away.

 

 

[PA.]

Use an Air Zound for around $50.

 

Caution, do not play video in a Doctor's waiting room or a Library.

 

 

 

[onetrack]

As regards the Airzound, I foresee a problem fitting an uncertified metal pressure vessel, charged to 80psi, in an aircraft - even though you only recharge it with a bike pump.

 

 

[onetrack]

Perhaps this is the answer? A hand-held electronic horn powered by a 9V battery and pumping out 112dB?

 

Aviation Safety Horn for Aircraft Emergencies & Ramp Safety Awareness

 

 

[Old Koreelah]

Thanks PA, the Airzound looks like what I've been looking for. Ideally I would mount the bottle next my leg and the horn below the spinner, but it looks like the actuator/button is part of the horn, rather than part of the bottle.

 

Thanks for that link, Onetrack. I've looked at some supposedly 115db 9v electronic items like that and they were barely noticeable a few car lengths away. I was impressed with the wig-wag that shop is selling, and will probably get a pair.

 

 

[Marty_d]

That's a bloody tragedy - an 8 year-old girl was one of the beachgoers killed.

 

I don't know what the circumstances were, and I don't know how I'd react in the same situation - but why would you attempt a landing on a crowded beach?? I know ditching is never a good option, but you'd have to at least consider it when the beach is full of people.

 

 

[Steve L]

Its a real tragedy Marty and a huge loss for the family especially if they were at the scene our hearts go out to them. I read in one of the media reports that it may have been a student and instructor in the Cessna. ( media is always right )

 

"Old Koreelah, a horn could be mounted forward facing in the cowl with a flap when closed would still form the

 

cowl shape, activated from the power supply to the horn through a model aircraft servo, light and easy as. I wouldn't be too concerned by getting sound pitch levels right to suit different hearing types, just get it as loud as possible. Some will hear it which in turn would alarm others.

 

 

[SDQDI]

I wonder if a simple little whistle, like what is on those vortex throwing footballs, couldn't be upscaled a little and made to work?

 

They would weigh nothing and it wouldn't be too hard to make a little pop out mechanism for them.

 

 

[onetrack]

Another advantage of a horn would be clearing remote or rural airstrips, of livestock and native fauna!

 

Never seen anything as amusing as on Cocos-Keeling Islands, where they use the runway ute to clear all the chooks off the runway before takeoff!

 

The Cocos-Keeling bantams were introduced by the Cocos Malays back in the 1800's, and they are truly feral.

 

Surprisingly, they survive very well on the islands, where you'd think the food supply was a bit limited.

 

They duck into the jungle around the coconuts, and you can't find them. They're surprisingly fast.

 

Worryingly, they can fly quite well for an extensive distance, and up to a height of probably 50 feet.

 

 

[Old Koreelah]

I've short-listed an electric horn:

 

"SETS" Piezo Electronic Hull Mount Horn - Innovative Lighting

 

I ve just got to get the American vendor to send it out of the US.

 

 

[onetrack]

Old Koreelah, you can use the Australia Post, ShopMate service, to get items out of the U.S., if the vendor is reluctant to do so, or the freight charges are prohibitive.

 

AP give you a postal address in their processing centre in Portland, OR, and the vendor sends it to that address.

 

Once it arrives, SM send you a notice that it has arrived and you pay SM and they then forward it through the AP system.

 

Works just fine for me, and I have acquired numerous parts at reduced freight cost from the U.S., this way.

 

 

[onetrack]

EDIT to above post - I forgot to mention, that many a time, a vendor in the U.S. will do free shipping to a U.S. address - particularly if you buy over a certain value.

 

So you can often get the item shipped to your Shopmate address for free, and you then only have the cost of shipping from the U.S. to Oz.

 

 

[eightyknots]

Its a real tragedy Marty and a huge loss for the family especially if they were at the scene our hearts go out to them. I read in one of the media reports that it may have been a student and instructor in the Cessna. ( media is always right )"Old Koreelah, a horn could be mounted forward facing in the cowl with a flap when closed would still form the

cowl shape, activated from the power supply to the horn through a model aircraft servo, light and easy as. I wouldn't be too concerned by getting sound pitch levels right to suit different hearing types, just get it as loud as possible. Some will hear it which in turn would alarm others.

Most light aircraft involved in an accident are a Cessna (according to the media).

 

 

[Marty_d]

Most light aircraft involved in an accident are a Cessna (according to the media).

Well in this particular case they nailed the brand...

 

 

[Old Koreelah]

Looks like the wing strength is totally dependent on the strut.

 

 

[Marty_d]

From memory of the 172, the wing would only have a couple of bolts and the top skin of the cabin. Strut provides the strength because it makes the triangle. It's not like the spars go all the way through the cabin.