R 44 Vne with floats

[Pilot DAR]

Would someone let me know the published Vne for the R 44 when flown with pop out floats, which are stowed? Is it changed from the Vne of the R 44 with no floats? Do any of the R 44 pop out float systems have an external air bottle for inflation?

Un related question, but while I'm here anyway.... Has anyone ever broken off, or otherwise damaged the ground handling ball, or related airframe structure, of an R 44 during un expectedly rough ground handling?

Thanks....

[TeenoHeli]

Pop-Out Floats

Available only on the Clipper II, pop-out floats have the same buoyancy as fixed-utility floats. The compact, low-profile design minimizes the floats' impact on the helicopter's cruise speed and makes it easy to get in and out of the helicopter. Pop-out floats add 65 pounds to the helicopter's empty weight and when not inflated stow in snug sleeves along the skid tubes. A trigger on the collective deploys the floats, which inflate from a compressed helium-filled, carbon-fiber tank located under the front seat.

from Robinson hope it helps ;)

[helisdw]

DAR,

From memory (and then a double check of the POH!) there is no Vne restriction on flying with the pop-out floats in the stowed position. I was told that there is an estimated 5-10kt penalty in having them fitted over an equivalent R44II with 'naked' skids, but this is unsubstantiated.

The Vne stipulation that does apply is when the floats are inflated: 80KIAS max for inflation (and for flight post-inflation).

The R44 I'm familiar with carries the inflation bottle under the front left seat - I am not sure how, or if, this affects the crash-worthiness of the seat... I'm not aware of any option for external positioning of the bottle, but I would not claim to be an expert on this matter.

An interesting point from the POH that could affect those in colder climates is that with an OAT of -10C or below, there may be insufficient charge for float inflation.

Simon

[sloanemallorca]

Helisdw correct about pop-out R44 Vne,

If stowed = normal R44 Vne(s) apply
Before floats inflated slow to below 80 knots
After this with floats deployed Vne is 80 knots

Also note: for deployment you must be below 4000ft AGL.

R44 POH Section 9-10.1

Ground Handling Ball can be replaced (Nut / Washer / Ball) if required, but if underside nose area infront damaged be prepared with chequebook!!

[John R81]

Out of interest - why 4k ft above ground level?

I could see reasons (atmospheric pressure) why one might limit altitude of inflation (but I think there is a pressure relief valve which deals with that) but can't think of a reason why the height above the ground would make a difference.

John

[Pilot DAR]

Thanks for the replies...

why 4k ft above ground level?


Complete guess on my part, but if you're popping the floats, you're either thinking precautionary landing, or you're already autorotating. In either case, I would imagine quite a drag penalty from the floats, so you would not want reduce your performance any more than necessary.

[cjbiz]

Not sure if the performance would be a deciding factor, provided that the aircraft is flown within the airspeed limits.

(but I think there is a pressure relief valve which deals with that)
My best guess is that it's an 'implied' altitude limit. The altitude limit is possibly on the pressure relief valve itself and reflects the inability of the unit to prevent the floats from going pop!

[helicopter-redeye]

There are Clipper I's wearing POF's as well as Mk II's. You just can't buy one as new any more.

There is also a Dart after market float kit which can be added to the other R44 versions (but not a Clipper I or II).

The bottle is not carried externally - the ground clearance would be insufficient. I would not want a hard landing with that big bottle under the LH seat (:eek::uhoh:)

h-r

[Pilot DAR]

Not sure if the performance would be a deciding factor, provided that the aircraft is flown within the airspeed limits

If you increase the drag, and maintain the speed, the power required will be greater (all other things being equal). Or, if there is no power, the "glide" ratio will be reduced. If the pilot is expecting a particular distance to be covered for the amount of altitude lost during autorotation, the pilot may be disappointed. The less dissapointment, the better, so no point in autorotating through a greater altitude than necessary...

But, just me guessing, I'm not an expert at this....

In airplane terms, a float plane will not glide as far as the same plane as a landplane, so delay it having to glide as a floatplane, as long as you can. (sorry to digress into fixed wing here.... back to helicopters at once!)

[helihub]

Interesting to compare this thread with the Guimbal Cabri thread (http://www.pprune.org/rotorheads/296022-guimbal-cabri-g2.html) also running at the moment - the Cabri has just been approved by EASA for float ops

[lelebebbel]

indeed... Cabri G2 floats:

flight enveloppe remains unchanged. [....]
safe deployment of the floats above 140 kts ! [....]
the gas cylinder is hidden in the luggage compartment, where it causes a negligible penalty in useful volume. Particularly, an airline "cabin-size" suitcase still fits inside[....]
the floats are folded in two clusters attached to the skids, which double as steps. The landing gear and the handling wheels remain standard. [....]

included in a fully dual circuit, an electronic device, of the highest reliability, triggers the floats when the helicoter's touches-down the water, in case the pilot lacked reaction or time to do so. This is usually more than half the occurences.[....]
the floats clusters can be removed and installed very easily by the pilot, thanks to nice quick-disconnect fittings
This feature makes possible to save payload and cost, installing the floats only when it's necessary.
Moreover, it makes possible to share the same floats amongst several helicopters of the same fleet.
Source: Hlicoptres Guimbal (http://www.guimbal.com/nouveau/index2.php?l=6#p=40)

Sounds like the Robinson system needs an update..

[sloanemallorca]

I believe the limit is due to the pressure differential in the floats to outside air pressure.

The increase in pressure descending 4000ft AGL would crush the floats, regardless of your height AMSL.

e.g. - 30ft = 1mb, 4000ft = 133mb. Therefore pressure increase exerted on the floats could be around 133mb at the bottom of the descent.

[cjbiz]

Pilot DAR

I see what you are getting at and yeah popping the floats early will increase parasite drag and therefore potentially reduce your expected 'glide ratio'.

My point however is that if you are at 5000' over the oggin, distance covered isn't your main concern, you're gonna get wet either way! Another way of looking at it is that you may prefer a reasonably uniform 'glide ratio' and therefore getting the floats out early will allow you to see straight away the performance you are acheiving as opposed to modifying it with a couple of hundred feet to go (although by that point the change would be trivial).

Personally I'd want to be set up nicely in auto, work out where I'm gonna end up and get the floats out early, better to have remembered them than to have travelled a couple of extra yards and go straight in! :)

[helicopter-redeye]

At 4000ft + you would have a reasonable chance of a restart if the engine could be relit, hence saving a wad of cash on the recharging of the float bottle - RHC just trying to save you money .... :ok: