Just to keep ourselves honest, the centripetal force doesn't actually toss the ice in fact the melted layer prevents a centripetal force from being applied so the ice is free to travel unaccellerated. I can't believe I'm starting this one again. :rolleyes: :)



If you'd like some heavy icing, Canada's East coast is a good place. Also, in Ottawa is an artificial helicopter icing machine (not its official name). I think you mentioned you were there once already, Nick.

I was told that Cougar ( one of the S92 launch customers) flys more time in known icing then any other operator in the world with their 3 Super Pumas. I saw a pic of one of the Cormorants somewhere with about an inch of ice on it.

S-92 Icing
 

How does an Ice Rate meter work?

Bless you heedem, for your precision is music to my ears. The ice requires hundreds of g's of acceleration to stay on the blade as it turns. Disbonded, it simply stops turning, and travels tangentially away from the aircraft. Who says pprune is not a learning experience!

The ice in the Maritimes is legendary, and Cougar is certainly one of the most experienced helo ice flying orgs on earth, perhaps right up there with the Russian Army. My friend Rick Burt has tales to tell!

I spent several days hovering a non-deiced S-76A in front of the Ottawa Spray rig, and it was a blast. Tossed off chunks from the blades that were about 1.5 inch square cross section and a foot long. Hover torque went from 65% to 95% due to the increased blade drag from the ice. Hover controllability and engine behavior were always fine. Vibes were, at times, eye watering.


The ice rate meters have several different technologies. One type has a thin post that hangs in the breeze and collects ice. As it does, its natural frequency shifts due to the mass change, and the base mount measures this shift. It is periodically heated to clear it to start the measurement cycle again. Another type uses optical pickups to see the ice on the post as it thickens, and reports that. They all read out in the cockpit, with a scale that (according to test pilot legend) starts off at "Uh-Oh!" and ends at "OH, SH*T!!"

Nick, while we are on the subject of questions on the S 92, the presentation you gave us at the SARForce conference showed the tail rotor on the starboard side in the 'tractor' position - is there a particular reason for this? I was given to understand that the decision on which side to put the TR on a helicopter was trading off the desire for uninterrupted airflow into the TR with the undesireable downwash (from the TR) forces on the vertical stabiliser. Certainly most helos have pusher, rather than puller TRs so is there another reason for selecting the puller option?

[email protected]:

We haven't moved the tail rotor on the S-92. It is where the Black Hawk parts are (the S/H-92 is the Black Hawk's clone, on steroids, its parts fit Black Hawk and Sea Hawk for future upgrades)

The BH had the TR where it is for balance and fold capability, to let it package itself into a C-130, no small feat for a 22,000 lb machine.

Some more questions if I may:

So how does the current get passed through the to the turning rotor head, is there some system of slip rings and brushes ?

Are there thermocouples on each heater mat to check they are working (or is the current measured) and if one stops working are the others switched of to prevent the ice causing vibrations if only one blade gets iced up.

Thanks Nick!!!

Another PPRUNE " groundschool"!!!!!

I agree...
Thanks NICK :D

Still more...
Nick. Why is it not an Anti-icing system?
Would it not be easier and simpler to expect icing and apply it as required rather than wait to accrue and deal with it.
What are the pro's and con's?

To: Nick

Several years ago I read about an anti icing or de icing system that used mechanical shock to dislodge the ice from the blades. It was not an application of heat to debond the ice from the blade but a magnetostrictive force that physically altered the surface of the blade, which broke the bond between the ice and the blade skin. The magnetostrictiove force was generated by an electrical charge that would change the shape of the blade and is the same principle used in some ultrasonic cleaners. Was this type of system ever considered on the S-92 or later Blackhawks?

Steve76, I was going to ask the same question...

My first thought is that it would take much more heat to prevent ice from accumulating, instead of removing it periodically. So "de-ice" would appear to require less energy than "anti-ice", and maybe produces less heat stress on the rotor blades (and systems) as well (though it seems more mechanical stress would be created with the higher weigh load of the ice).

De-ice uses about 10% of the electric power of anti-ice, due to the tremendous heat differcence between the two philosophies. Also, runback is a big problem in anti-ice systems, where the water runs back off the heated leading edge, and then freezes, making the heater mats need to be much bigger (and more power consuming).

The heat is of no structural signficance at all to the blade.

The system uses slip rings to transmit the amperage to the blades.

The other technologies (like piezo-electric shocking of the blade to force mechanical disbond) sound great, but are nowhere near mature enough to be considered.

Point of information, years ago I participated in helicopter icing test involving the -53 and (no kidding) a UH-1 with pneumatic boots on the leading edges of the blades.

The boots worked well enough as I remember but they didn't stand up to abrasion well enough.

The CH-47D has an unused generator pad on the aft transmission (last I saw one it was unused) which was intended for hot blades. A few of these blades were rumored to have been produced before someone decided they weren't needed. I have two personal experiences of contradiction to that decision. Unforcast, I swear.

Slip rings ....

!!!!!!!!!! AAAAAAHHHHHHHHHHHH !!!!!!!!!

Be it known the RW-1 had to assist the electricians on the CH-53E in phase maint, cleaning the blade fold slip rings were one pain in the behind hehehe ......

!!!!!!!!!! AAAAAAHHHHHHHHHHHH !!!!!!!!!


sorry ...... :)

Flight Safety: Great minds think alike ??? Hahaha :)
Nicko: Thanks mate. Another great ground class.

S92 development ?
 

Anyone know how the S92 development is going? It seems to be incredibly slow coming on line. Is there a projected date for civilian certification ? Are there many firm civilian orders yet ?

It can't be to far away, it's been seen flying around New York. You'll see one in Mr Deeds (nice piece of marketing Mr Sikorsky!!)



http://img.photobucket.com/albums/v1...y/S92Blake.jpg

My understanding is development is coming along nicely with a projected initial type certificate late this year/early next year.

I think first deliveries late 2003 possibly. Cougar Helicopters of St. John's, Newfoundland still on target to be launch customer I believe.

Can't really say how many firm civvy orders though, I have a hunch it's not too many at this stage.

coalface,
The development of the S-92 is moving along at a pace much faster than its contemporaries. Note that we developed the machine in about half the time of the EH and NH. As the program manager, I am the one to be blamed if it were otherwise! I made the chart below based on a quick net search, and included some sites that have the data. Note that the NH-90 dates are not very precise, perhaps someone from the program is reading this and can improve the accuracy.

Here are some comparisons:

First Flight---Cert (years)---Enter Service (years)

S-92, 1998---2002 (4 yrs)---2004 (6 yrs)

EH-101, 1987---1994 (7 yrs)---2000 (13 yrs)

NH-90, 1995---2004 (9 yrs)---2004 (9 yrs)


The S-92 is just about completed its certification data flight tests, with TIA expected in a few weeks (by mid Sept) and then FAA flight tests following quickly. FAA approval is expected in December of this year. There is much technical data on the militrary and civil versions at www.sikorsky.com

http://www.rotorhead.org/military/cormorant.asp

http://www.vectorsite.net/aveh101.html

Thanks for the info, Nick.

The EH-101 entered service into RN on 1 Dec 1998. A-W consortium formed sometime around 1981, but not sure when EH-101 work was started.

http://www.helis.com/news/2000/eh101tril.htm
http://www.helis.com/timeline/westland.htm

In any case, your timelines for EH-101 get reduced slightly.

I'm curious as to how S92 is so much faster. Are you that good? Was it less work due to similiar helicopters as a model? Is it because only one company is building them?

One more thing, did you receive an email from me recently?