"I'm looking for some information and informed experience on helicopter ice detection systems...

such as which ones are reliable, which ones aren't worth jack, how much warning they give you before the aerodynamic affects are noticeable.

Any info much appreciated."

I'm flying Super Pumas certified for flight in known icing on Canada's East coast, but flight in severe icing is prohibited, which we consider any freezing precip.

As far as detectors I've flown with many of them and none seem to work, giving warnings in clear blue sky and no warnings when we have inches of the stuff on us. The best indicators are the mirrors and wipers, and of course the torque, which will initially climb about 3 to 4 percent if you neglected to put the kit on for any reason. Having flown S61's out here at night for years watching for that torque rise (we would not go out in known icing of course, but forecasting being what it is, you sometimes encountered cloud below zero you couldn't see at night) I must say a certified for flight in icing aircraft reduces my daily stress considerably.

Hello sycamore,
at the moment, I'm writing my PhD-Thesis, and would like to use one of your images showing iced rotor blades, you posted in #48 in the introduction of my work.
Are these your private images, or where did you get them from? If they're your images, do you allow me to re-use them or one of them in my thesis?
Kind regards,
MarSch

Mar you might check:

1, SAE Paper 2003-01-2093 authored by Robert Fleming that traces the technical story of developing the UH-60 from a design point of view.
2. Also worth looking up the US Army Flight Test reports on their sequential icing flight tests with succeeding versions/configurations of the UH-60.

In all of these, you will see that both design engineers and flight test engineers/test pilots were well aware of the impact of droplet size/temp.

Have at it.

Thank you very much for your answer, John.
I'm not searching for detailed studies, since I already have many papers (including those of R. Flemming) about ice accretion in my library. I'm only searching for an image to illustrate ice accretion in the context of rotorcraft in the motivation of my work. However, any of the publications in my library contains photographs of a quality comparable to those in sycamore's post. Therefore, I hope that sycamore will reply to provide information of the origin of the posted photographs.
Regards, MarSch

The US Army Flight test reports are replete with very good photos. Since you are doing a doctoral thesis, you might write or phone them and obtain some copies of the originals. That test organization is now located at Ft Rucker AL

MarSch,thank you for the compliment vis the photos;most were taken by one of the engineers,responsible for the multitude of instrumentation that we had fitted to each of the aircraft,when I was a T-P at AAEE Boscombe Down,when we first began to do serious ice/snow/freezing rain trials in Canada and Norway,over many winters.
It should be remembered that all our helos of the time used the same blade section NACA0012,a fairly conservative symmetrical section,whereas now blade sections are much more exotic and may well not give similar results.
You probably know about the NRC Spray rig ,and snow blower in Ottawa(gone now) that we used to initially establish some basic icing flying in the hover and covering a variety of temperatures and water droplet size and flow rates,and see if the ice would `self-shed`,in low altitude forward flight,or not!! Also the effects on the engine/intake configuration,and whether heating them or leaving `cold` would be beneficial.
We would then go into cloud,picking a time/day when there was a stratiform cloud layer,hopefully at a suitable base altitude of 2-3000ft,,and then `nibble` into the cloudbase for a short period to then drop out,then back in again,repeating as necessary until we reached a limiting torque rise,if there was no noticeable ice shedding,or if it could be induced in turns ,etc.We also had various detectors to calibrate ice accretion,temperature,droplet size and flow/mass rate,and the information would be correlated with the spray-rig.We did suffer engine problem with damage to the Wessex5 engines due to the small clearances between the Inlet Guide vanes and the compressor blades.This was later modified by fitting modified Sea-King IGVs to the first 2-3 stages in the compressor.We also had `mushroom` intakes fitted to the Sea-King( like all Russian MiL helos).
I suggest you use the photos with a credit to AAEE anyway,as I`m not certain which I may have taken anyway.
In retrospect the only way is to have fully automatically controlled blade
de/anti-icing,and engines that have a centifugal compressor/fan as the first stage,like the Astazou in the Gazelle and Nimbus in the Wasp/Scout..
Testing in icing conditions is a long and tedious job,and one can always be `bitten`...!!
I wish you well with your thesis,and happy to answer further,bearing in mind we were doing this 40+ years ago,,,but icing is still there..
Rgds,Syc

@ John: Thank you again for your hint regarding US Army flight testing. Unfortunately, I didn't find an appropriate photograph in their reports in the web. Therefore, I wrote an e-mail to Fort Rucker, asking for some pictures and permission to use them.
@ scy: Thank you very much for your detailed description of the conditions and procedure during testing. I've noticed that AAEE Boscombe down doesn't exist anymore. However, I'm not sure about the rights to use their images. Thus, I've contacted the British Ministery of Defence hoping they may provide information about the rights-holder of the photographs.

Anyways, thanks again to both of you for your help.
Finally, I've got a rather simple question: Are you still in business or already retired?

Kind regards,
MarSch

MarSch,long time retired...
you might want to read `AGARD ADA 173807`or search for earlier reports.
Also consider the tail rotor,and rear stabiliser,if high or low mounted;in/out of downwash/exhaust heating,possible stalling,affecting autopilot...similar to some work done on high mounted tailplanes ie ATR-42.

Retired, but still very interested in the subject.

Sycamore, thank you for the referenced report. In fact, all the test reports are much closer on the application, than my work will be. I'm rather looking onto the involved physics such as drop impact, nucleation and solidification; and finally their mutual interaction. Hence, a further step is still required from my work towards a potential improvement of numerical or theoretical icing codes...

"...but still very interested in the subject." Obviously... ;-)

Thanks again for your support and information!

MarS,you might try Shawn Coyle ,,or NRC in Ottawa,if it`s still extant ,as they should probably have helpful reports..

MarSch - The people you want at Boscombe Down are QinetiQ but don't expect anything for free from them.

I recall the Canadian National Research Council in Ottawa did some extensive experiments on helicopter icing in the 70's and early 80's. Perhaps you may wish to contact them.
https://www.nrc-cnrc.gc.ca/eng/index.html

EDIT
Just talked to Dean at the NRC .. I assume you are the person from Germany he is talking to.
He told me they are doing some research in their files to help you.
We had a great conversation about icing.
Great folks at the NRC.

Hello again,
exactly; I'm the person from Germany, that contacted nearly all institution somehow related to icing, and in particular helicopter icing comprising the NRC in Ottawa, people from NASA Glenn, and several others. I finally got permission from the Ministry of Defense, UK, to re-use the images in this thread. I asked them who holds the rights for these images, since Boscombe Down does not exist anymore; and obviously they do.

Many thanks again for the efforts of all of you.