Performance question
Guest
Posts: n/a
Performance question
New to flying the 300CB (and find it superior to the R22)and would like some advice on how to safely determine the ability of the helicopter to hover out of ground effect. There are no charts or info in the P.O.H. regarding O.G.E. only I.G.E. info is published. Would like to know if an approach to a "high" pinnacle that is surrounded with trees is going to be safe without the benifit of ground effect.
Many thanks in advance
Many thanks in advance
Guest
Posts: n/a
Not sure I understand your flying here. If you are making an approach to a high pinnicle surrounded by trees why do you wish to hover oge ?? If you need to indicates you cannot land so why put yourself in the avoid curve ??
If you can land you should not be worried about OGE what you should be worried about is your power check to get in and be able to get out again as i presume the area is a confined area
With a 300C generally you need 2" of MP for towering T/O and 6" to 7" mp for a landing. Do the power check straight and level with about 45 knts for landing.
Not sure on a CB has less guts than a C model. If in doubt please ask an experienced instructor to show you the limitations / power checks. Even if you find the OGE / IGE figures remember this is the absolute limit of the machine on a perfect day flown by a test pilot.
If in Doubt do not try it, it is better to be an old pilot than a bold pilot !!
Have a nice one
If you can land you should not be worried about OGE what you should be worried about is your power check to get in and be able to get out again as i presume the area is a confined area
With a 300C generally you need 2" of MP for towering T/O and 6" to 7" mp for a landing. Do the power check straight and level with about 45 knts for landing.
Not sure on a CB has less guts than a C model. If in doubt please ask an experienced instructor to show you the limitations / power checks. Even if you find the OGE / IGE figures remember this is the absolute limit of the machine on a perfect day flown by a test pilot.
If in Doubt do not try it, it is better to be an old pilot than a bold pilot !!
Have a nice one
Guest
Posts: n/a
kjf, I have pondered a similar question for the R22 - although the R22 does supply OGE hover limitation charts, there are no charts for performing a power check prior to making a high altitude landing (as there are in more sophisticated turbine machines). Reaching full throttle is the main concern here because as we all know as the airspeed bleeds off power requirements go up and over pitching will result in a loss of Nr. The only semi practical check I know of in these smaller machines is to try hovering OGE at approximately the same altitude as your LZ (only safe in the pinnacle situation where you can remain outside of the HV shaded area). Not sure about the 300, but the R22 limit manifold pressure chart won't be much assistance in the air in determining where full throttle will actually occur (especially the R22BII) partially because of the newer placard format and also, as stated previously, because your machine probably isn't new out of the box and won't be performing as well as it did on test day. A little helpful advice is to always assume you will reach full throttle on your way to the spot - and always have an escape route. Maybe the high altitude confined area would be better hiked into.
Guest
Posts: n/a
I was told the reason the 300CB has no OGE performance charts is because it was brought out in a hurry to get a foothold in the training market after Robinson had a few problems and were grounded in the early 90's.
The numbers as I used to teach for the 300CB or 300C (they are fairly similar in performance, the C having a little extra grunt) approaches and departures:
After powercheck at 42 knots S&L (approx 18-19" MAP depending on the conditions):
Less than 4" MAP: Running Landing
4" MAP: Zero/Zero Approach
5" MAP: Normal Approach
6" MAP: HOGE (+1" to arrest descent at the bottom, very handy)
After powercheck at 2 foot hover (approx 24-25" MAP):
Less than 1": Running Takeoff
1" MAP: Cushion Creep
1-2" MAP: Towering Takeoff
More than 3" MAP: Vertical Climb OGE can be acheived.
Of course some of these approaches will take you through the H/V curve. I strongly recommend a good deal of practice using these techniques with an instructor at the training field before attempting anything else.
You should also really question whether you are doing the right thing by making a limited power approach into a confined area. Less weight, heat or height may be a better idea than trying to get into something you can't get out of.
Hope this is useful.
Gov
[This message has been edited by The Governor (edited 19 April 2001).]
The numbers as I used to teach for the 300CB or 300C (they are fairly similar in performance, the C having a little extra grunt) approaches and departures:
After powercheck at 42 knots S&L (approx 18-19" MAP depending on the conditions):
Less than 4" MAP: Running Landing
4" MAP: Zero/Zero Approach
5" MAP: Normal Approach
6" MAP: HOGE (+1" to arrest descent at the bottom, very handy)
After powercheck at 2 foot hover (approx 24-25" MAP):
Less than 1": Running Takeoff
1" MAP: Cushion Creep
1-2" MAP: Towering Takeoff
More than 3" MAP: Vertical Climb OGE can be acheived.
Of course some of these approaches will take you through the H/V curve. I strongly recommend a good deal of practice using these techniques with an instructor at the training field before attempting anything else.
You should also really question whether you are doing the right thing by making a limited power approach into a confined area. Less weight, heat or height may be a better idea than trying to get into something you can't get out of.
Hope this is useful.
Gov
[This message has been edited by The Governor (edited 19 April 2001).]
