% Power
- Thread starter davemgill
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David,
We have considred this, and hope to add it at some point. We even saved space on the screen for this information.
However, the % HP requires a lot of data to do accuratley. For rich of peak operation, you need RPM, Manifold Pressure, OAT, and altitude. For lean of peak, all you need is fuel flow. The real trick is deciding if you are ROP or LOP!
We have considred this, and hope to add it at some point. We even saved space on the screen for this information.
However, the % HP requires a lot of data to do accuratley. For rich of peak operation, you need RPM, Manifold Pressure, OAT, and altitude. For lean of peak, all you need is fuel flow. The real trick is deciding if you are ROP or LOP!
D
Dave(Guest)
Guest
How is this coming along? There's a discussion going on right now on the Van's forum about how two of your competitors have this feature.
- Joined
- Mar 23, 2005
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Percent power is still a possible future feature, but there's no update at this point.
On which site is the discussion that you mention?
On which site is the discussion that you mention?
D
Dave(Guest)
Guest
Sorry it took a while to reply. I forgot to check back. :
Here's a link to the topic on the Vans Air Force Forum discussing percent power and a bunch of other stuff.
http://www.vansairforce.com/community/showthread.php?t=4535
Dave
Here's a link to the topic on the Vans Air Force Forum discussing percent power and a bunch of other stuff.
http://www.vansairforce.com/community/showthread.php?t=4535
Dave
khorton
New Member
I wonder how complicated an algorithm the other EFIS units use to calculate percent power. It is easy to display a number and call it percent power. The hard part is making it accurate.
The Lycoming power charts provide percent power as a function of altitude, temperature, rpm and MP, assuming the mixture is set to best power mixture. But, many people will want to lean more than that, so to provide an accurate percent power you really need to bring fuel flow into the mix too. And then you need to make a whole bunch of assumptions, unless you have access to a dyno in an altitude chamber to develop your algorithm.
How accurate do people expect for the percent power number? Getting within 10% is easy. Getting more accurate than 5% will take a lot of work, and a lot of dollars for the testing to validate the algorithm.
The Lycoming power charts provide percent power as a function of altitude, temperature, rpm and MP, assuming the mixture is set to best power mixture. But, many people will want to lean more than that, so to provide an accurate percent power you really need to bring fuel flow into the mix too. And then you need to make a whole bunch of assumptions, unless you have access to a dyno in an altitude chamber to develop your algorithm.
How accurate do people expect for the percent power number? Getting within 10% is easy. Getting more accurate than 5% will take a lot of work, and a lot of dollars for the testing to validate the algorithm.
- Joined
- Mar 23, 2005
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Khorton,
We've had the same issues with % power when we have thought about it in the past as well. One of the most obvious issues with % power is that the calculation needs to know your altitude. It also needs to know if you are LOP or ROP. Most engine monitors out there (ours included) do not know your current altitude. We will be able to do this in the near future as we get more connectivity between an EFIS and an EMS, and then we may be able to explore displaying % power for some engines that have known tables. I have no idea what other companies do, but altitude makes a 25% difference in power between sea level and 13K feet, so this is a major factor.
The other complex issue is detecting if you are LOP or ROP, since the calculations are totally different on each side of the peak. It's easy to detect LOP or ROP in the short term after the pilot presses a button and starts leaning, but once the altitude or OAT changes much, this may cause problems. We'd rather not display a % power number that is way off. Once again, once we have an EFIS, we can probably use the altitude and OAT numbers in order to see fi we're still accurate.
We try our best at Dynon to always give the pilot an accurate number that isn't frought with corner cases where the reading could be false, and % power is no different. We'll do it once we feel it can be done correctly and is accurate.
We've had the same issues with % power when we have thought about it in the past as well. One of the most obvious issues with % power is that the calculation needs to know your altitude. It also needs to know if you are LOP or ROP. Most engine monitors out there (ours included) do not know your current altitude. We will be able to do this in the near future as we get more connectivity between an EFIS and an EMS, and then we may be able to explore displaying % power for some engines that have known tables. I have no idea what other companies do, but altitude makes a 25% difference in power between sea level and 13K feet, so this is a major factor.
The other complex issue is detecting if you are LOP or ROP, since the calculations are totally different on each side of the peak. It's easy to detect LOP or ROP in the short term after the pilot presses a button and starts leaning, but once the altitude or OAT changes much, this may cause problems. We'd rather not display a % power number that is way off. Once again, once we have an EFIS, we can probably use the altitude and OAT numbers in order to see fi we're still accurate.
We try our best at Dynon to always give the pilot an accurate number that isn't frought with corner cases where the reading could be false, and % power is no different. We'll do it once we feel it can be done correctly and is accurate.