Open cockpit flying-Drumming in military helmet

[Biggles of 266]

Has anybody else encountered 'Drumming', when using an Ex Military Mk4A RAF helmet in an open cockpit.

After a recent 6 hours flying, I have found it to be most unpleasant, and am contemplating my seemingly expensive mistake. I find that the propwash beats on the outside, and the noise is transmitted directly into the ear pieces. The result being an effect like being beaten on the head repeatedly by a rubber mallet.

I suppose that this kind of helmet was never designed for high airflow, but I wondered if anybody has encountered, or perhaps solved this problem.

I wondered if mine were perhaps too small, as the ear cups seem to be touching the inside of the shell when fitted, perhaps causing the problem.

Has anybody else used this kind of helmet succesfully in an open cockpit?

Your input would be appreciated.
Guy

[ChrisVJ]

Obviously you need an airflow disturbance kit. (The picture sprang unbidden to mind!)

[gaxan]

I use a Mk3c helmet and have had no problems with it until yesterday when one of the visor brackets snapped. Luckily I noticed before I went flying. Its most unpleasant when it happens in the air! A chat with the others in the group revealed that this is quite a common problem with all marks of helmet. I assume its a fatigue problem due to buffeting. If you are being buffeted by the slipstream - is your seating position in the cockpit too high?

[Miles Magister]

Try contacting the team at Caledonian Chipmunks as they have a qualified helmet fitter. You may also wish to try talking to some of the shuttleworth pilots as they are all experienced RAF test pilots.

MM

[S205-18F]

It is a common problem we have it with our Luton Minor and the easiest fix we have found which reduces it, is to use earbud headphone under the normal earphones and use a 3.5mm to 1/4" adaptor! The volume needs to be turned down as the earbuds are very good (LOUD)! There are a few companies in the States that will sell you purpose made CEPs with sockets etc to modify your helmet but being true tight Scots we have been experimenting with earbuds!!! Sony ones for mobile phones with mp3 player are so far proving to be best.
Make sure the type you acquire dont have solid stems on the wire exiting the body this becomes uncomfortable although you can break them off!
Earbuds are the ones that come with the removable silicon adaptor that allow you to get a snug fit in the ear canal.

['Chuffer' Dandridge]

I had the same problem, so I filled the insides of my helmet with foam, seemed to do the trick. I even considered some of that 2-pack stuff you can buy in a can but the foam sheets did the trick for me.

I liken it to having your head in galvanised dustbin...:{

[Biggles of 266]

Thanks for all the input, I think I have decided on three directions:

1. A bigger windsreen. (looking for one similar to a Tiger Moth)
2. A thinner cushion
Both of which may get me lower and out of the airflow.
3. A Bigger helmet. I have a medium helmet currently, and am going to try and locate somebody with a Medium Broad or Long to try.

My impression is that the problem is entirely Helmet induced. If I push my fingers into the ear cups, and effectively break the seal, the noise reduces hugely.
So I wonder if a gap in the sealing ring at the top might help?

Thanks for the foam tip, I think that might work with a bigger helmet. I have tried Bubble Wrap already, but with no improvement.

Unfortunately with the helmet fitted, the ear cups are touching the inside walls of the fibreglass. Consequently the slightest noise on the outer skin is transmitted directly to the ear. Even if I just brush the outer skin with my fingers, it is very loud. Propwash .....Ugh!

Again, thanks for the suggestions
Guy

[eharding]

Oregon Aero sell some very good after-market replacement parts for Gentex HGU series helmets, including replacement ear cups and padded velcro spacers to fit between the earcup and the helmet skin. However, if those is no room between the earcups and the helmet to introduce some padding, you may need a larger helmet shell.

I also highly recommend the CEP eartip speaker system - Communications & Ear Protection, Inc. (http://www.cep-usa.com) - certainly stopped me going deaf in the Pitts when using a Gentex helmet. You can get the kits (or have it fitted) by various retailers, but you can purchase direct from the factory by phone at a substantial saving.

[NavEx]

Do you leave your visor cover on? If you just push it back behind the visors it catches in the airflow once airborne and inflates then buffets. I had the same problem and found that by uncliping my visor cover each flight it helped. Also try positioning the other visor that you are not using just above the in use visor, rather than fully to the rear.

I've flown many hours in open cockpits in Mk4 and Mk10 helmets, if correctly fitted I have found them comfortable and very suitable.

I would advise against filling the helmet with a solid foam. The helmet is desgined that in a blow the shell takes the force and if needed defroms into the cavity. If you fill that cavity with foam the force is transmitted straight to your head.

[Biggles of 266]

Thanks NavEx that's Sound advice. I hadn't thought of that. Could you tell me if the ear cups touch the outside shell on yours, or not?

I'm trying to work out if mine is too small for me, and it is an expensive operation to go out and buy a bigger one, only to find that it is just the same.

In every other respect, other than the awful noise, it seems to fit me, but I reckon if it had 1cm gap between the cups and the inner shell, the noise transmission would be greatly diminished.

I know also that I can improve matters with a bigger windscreen, as I am being somewhat battered about. But that is a job for the winter.

Many thanks
Guy