Hi all just updated my Sky demon to find they have added a glide safe option. Not really that much help for us as we should know it out the window. But did get me to thinking just what is thaverage glide ratio for a helicopter.

Cheers Chippy

Always less than you think!

Should be in the POM.

R44 is 4.7:1 on an average day. (4700ft horizontal for every 1000ft vertical.) But depends on airspeed at start of glide....

It's not gliding - it's falling with style! Apologies to Toy Story;)

Hi Jim ... are you sure we are right! Heli descent in auto circa 1800 to 2000 fpm so from 1000 feet we hit the ground in circa 35 secs, which at 60 mph auto speed gives a range of around 2500 feet! Sounds mor elike 2.5 to 1. OR where have I gone wrong! DRK

Well, great DK, I want to bow to you. But the POM for R44 Raven II states 4.7:1.

And, from my experience over the past 9 years flying them, I'd say it's spot on - in average circs. As I intimated, going into a glide from a hover is a different thing - and the ratio shortens.

A 90/90 R44 auto (as taught by the factory on the safety course) gives astonishing results - 90kts at 90% rrpm.

Quote: A 90/90 R44 auto (as taught by the factory on the safety course) gives astonishing results - 90kts at 90% rrpm.


I would imagine the low-rpm horn would be going off.

Hi again Jim ... I spent yesterday at Dunsfold doing nothing more than practice autos (hi speed-low speed and hi & lo rrpm) and must confess that even the humble Hughes 300C at 60 knots into wind seems to make better than my 2.5 to 1 theory. But figs are figs. Anyone out there who can offer something definitive? Dennis K.

Rate of descent varies with size/weight too. I remember seeing 3800 fpm on a Vertol!

R44 ROD in Auto at 60kts is less than 1800fpm. The published figure of 4.7:1 can be achieved when using the max. range configuration (90%RRPM/90kts)
At 90kts (= 9,100ft/min) forward speed, you would get 4.7:1 at a descent rate of just under 2,000fpm.


I would imagine the low-rpm horn would be going off.

Yes. Minimum allowable RRPM in autorotation is 90% though, so you are within limits.

I wonder whether the R44 may be a rather atypical helicopter, with a low RoD in autorotation.

I haven't flown one for many years, but recall that although the limitations section include a max DA of 14,000ft, there is another "altitude" limitation of 9,000ft agl "as the aircraft would otherwise take more than 5 minutes to land in the event of a fire". I suspect this implies a low RoD (rather than a rapid escalation of a fire in this type). I cannot recall a similar limitation in other types.

in mi-17 speed is 65kt and descent around 2000ft/min, but when you start flare(110-120ft agl), it takes some time and distance to get speed down for touchdown.