R44 power curve
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R44 power curve
HI All - first post here after reading about a hundred pages of various amazing threads :-)
Is there any place one can obtain a power curve for a R44 II - ideally expressed in MAP inches vs IAS? I know I can probably make one myself in ~2 hours of flying but was wondering if someone has done this already. I did Google it (and searched here) but found nothing.
Why - just trying to better understand the normal power variances between IGE / OGE / S&L at some standard speeds (55, 70, 100, 110kts), etc., to develop quicker / better power margin assessments.
Thanks!
V
Is there any place one can obtain a power curve for a R44 II - ideally expressed in MAP inches vs IAS? I know I can probably make one myself in ~2 hours of flying but was wondering if someone has done this already. I did Google it (and searched here) but found nothing.
Why - just trying to better understand the normal power variances between IGE / OGE / S&L at some standard speeds (55, 70, 100, 110kts), etc., to develop quicker / better power margin assessments.
Thanks!
V
From my experience, UK, sea level, R44 Raven 2 @ approx 2100lbs;
hover@ 20", rising to 21" @ 10kts as you come off the ground cushion. 16"@55kts straight and level. 22.5" @115kt.
you can base a curve on that. Roughly add/subtract an inch for every 100lbs
hover@ 20", rising to 21" @ 10kts as you come off the ground cushion. 16"@55kts straight and level. 22.5" @115kt.
you can base a curve on that. Roughly add/subtract an inch for every 100lbs
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Hot and Hi - thanks!
Sadly, I can't - this is what my POH has a standard OGE hover ceiling vs gross weight chart (I tried to embed it here but the site doesn't let me add images until I have 10+ posts :-).
I don't know how to get a MAP for OGE at sea level, standard day, at 2100 lbs, from that chart, for example. I know I can OGE at 10,000ft at 2100lbs on a standard day at full throttle (which would be ~19" at that altitude I believe), but I don't know how to convert that to sea level. Perhaps I am missing something...
Thanks!
Sadly, I can't - this is what my POH has a standard OGE hover ceiling vs gross weight chart (I tried to embed it here but the site doesn't let me add images until I have 10+ posts :-).
I don't know how to get a MAP for OGE at sea level, standard day, at 2100 lbs, from that chart, for example. I know I can OGE at 10,000ft at 2100lbs on a standard day at full throttle (which would be ~19" at that altitude I believe), but I don't know how to convert that to sea level. Perhaps I am missing something...
Thanks!
Perhaps I am not understanding this properly.
No one flies on a standard day, it may exist somewhere but it seems more elusive than a positive comment about a robbo.
Any reading will vary depending on density so it's usefulness seems limited and basing a rule of thumb on what you see would need to be in the context of prevailing conditions.
If this was a relevant chart it would be in the flight manual.
No one flies on a standard day, it may exist somewhere but it seems more elusive than a positive comment about a robbo.
Any reading will vary depending on density so it's usefulness seems limited and basing a rule of thumb on what you see would need to be in the context of prevailing conditions.
If this was a relevant chart it would be in the flight manual.
just trying to better understand the normal power variances between IGE / OGE / S&L at some standard speeds (55, 70, 100, 110kts), etc., to develop quicker / better power margin assessments
If this was a relevant chart it would be in the flight manual
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In Hovering The difference between IGE and OGE is nearly 7 % of power / take of mass lose
This rule is totally independant of the altitude...But you need to read the power in IGE first to know the OGE power.
At the same place and weight :
If you have 20 " IGE, you need 20"+ 7% = 21.4" OGE
If you have 75 % torque IGE, you need 75 %+ 7% =80.25 % OGE
If you have 13° pitch IGE, you will need 13°+ 7% = 14° OGE
If you are at 2000 lbs IGE, for the same power, you have to be only at 2000 - 7 % = 2000- 140 = 1860 lbs OGE
anyway what you use : MAP, torque, pitch degrees, weight the rule is "approximative, but "useful"
This rule is totally independant of the altitude...But you need to read the power in IGE first to know the OGE power.
At the same place and weight :
If you have 20 " IGE, you need 20"+ 7% = 21.4" OGE
If you have 75 % torque IGE, you need 75 %+ 7% =80.25 % OGE
If you have 13° pitch IGE, you will need 13°+ 7% = 14° OGE
If you are at 2000 lbs IGE, for the same power, you have to be only at 2000 - 7 % = 2000- 140 = 1860 lbs OGE
anyway what you use : MAP, torque, pitch degrees, weight the rule is "approximative, but "useful"
Not really sure I understand the question, but I have a reasonable amount of experience with the R44 around San Francisco. To pick up into a 6' hover generally takes around 21". OGE varies with load, temperature and the aircraft, but in my experience around 22-23". Not sure why it should be different anywhere else in the world! Obviously an OGE hover at sea level isn't strictly possible, unless you potter over to Death Valley.
Rules of thumb can be quite dangerous if people don't understand the context.
Place, temperature, wind and altitude all change and suddenly 7% is a small drop in a big ocean.
For an aircraft that is notoriously power constrained and involved in too many loss of (insufficient) power accidents there is no substitute for thorough planning.
Place, temperature, wind and altitude all change and suddenly 7% is a small drop in a big ocean.
For an aircraft that is notoriously power constrained and involved in too many loss of (insufficient) power accidents there is no substitute for thorough planning.
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Thanks guys - great stuff!
Like I said, the idea is to develop a better understanding of the power difference among various flight regimes.
I specified 'standard day' only to remove the OAT dependency (that many of you correctly noted) from the question. I think I have enough info from POH on performance-vs-OAT dependency to extrapolate from the standard day if needed.
I will also do some flying with a notepad and will post here what I get.
Thanks again.
V
Like I said, the idea is to develop a better understanding of the power difference among various flight regimes.
I specified 'standard day' only to remove the OAT dependency (that many of you correctly noted) from the question. I think I have enough info from POH on performance-vs-OAT dependency to extrapolate from the standard day if needed.
I will also do some flying with a notepad and will post here what I get.
Thanks again.
V
R22 Butters - a zero/zero is a zero speed landing - you don't come to the hover - it's like a running landing but with no run-on if that makes sense.
The technique can be used in dust/snow (when not power limited) to minimise the downwash effect but can be used (carefully) when you don't have enough power for OGE and are right on the limits for IGE.
The technique can be used in dust/snow (when not power limited) to minimise the downwash effect but can be used (carefully) when you don't have enough power for OGE and are right on the limits for IGE.
BOBAKAT - I don't think your 7% is accurate (and some of your figures don't add up), the only thing you can say with certainty is that you will need more power to hover OGE than IGE, other than that it is just misleading to try and put rule-of-thumb numbers on it.
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Crab, i don't try to convinct anybody. I learned and used this rule since 1977. I just say the difference between IGE and OGE is always : + 7% of power or : - 7% of weight.
This rule is totally independant of the temperatue, the Pressure, the kind of helicopter or so.
BUT only at the same place , At the same time. Please check for you next flight : Power in IGE and then climb OGE and read the power again...I think you read around +7%
Maybe, check your chart and please look the power diffrence at the same Zp, t° Mass in IGE and OGE ....Maybeyou find 7%
Sure, if you read your power IGE today close to sea level and your power tomorrow at 3000ft OGE this rule is totally false.
BUT it's very useful when you work on the same area and maybe limit the number of "SWP"
This rule is totally independant of the temperatue, the Pressure, the kind of helicopter or so.
BUT only at the same place , At the same time. Please check for you next flight : Power in IGE and then climb OGE and read the power again...I think you read around +7%
Maybe, check your chart and please look the power diffrence at the same Zp, t° Mass in IGE and OGE ....Maybeyou find 7%
Sure, if you read your power IGE today close to sea level and your power tomorrow at 3000ft OGE this rule is totally false.
BUT it's very useful when you work on the same area and maybe limit the number of "SWP"