Just Flight PA-28 Arrow underpowered?

I compared the Carenado and Just Flight PA28s in flights from KOAK to KMHR and back. Got the following results:

Carenado
Altitude: 3500’
MP: 24 in
RPM: 2300
TAS: 128

Justflight
Altitude: 4500’
MP: 24
RPM: 2300
TAS: 104

Same weather/same settings/same payload, etc.

I believe that these are supposedly both modelled on the same 200 hp Lycoming engine, but for some reason the Just Flight model seems underpowered.

Why not look at the performance charts in the actual POH for the Just Flight version and test a recommended setting? My test this morning showed the actual numbers spot on with what the POH said that I should expect.

Do the same thing with the Carenado and then you will know. It is a different model year, so the performance may be different. That said, I suspect that you will find that the Carenado version is overpowered with respect to reality. The real Arrow III is not a fast airplane…

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Well I have reviewed the POHs and the POH is the same for both aircraft as they are supposed to be modelling the same version of the aircraft. I doubt if the model year has much bearing but perhaps I am wrong. I find the performance tables confusing as they give different power settings for different altitudes, etc. but don’t appear to me to provide you with the airspeed that should result. You may be right that the Carenado is overpowered but clearly if they are supposed to be the same aircraft version, they can’t both be right. And on a relative basis, the Carenado is more powerful (or has less drag) than the JF. (The props are different which may make a difference?)

Not really, it even starts with 2 vs. 3 blade propellers, the latter causing more drag.

ODM page 13 for example provides you the expected KTAS. What are you missing exactly?

As for Carenado: Why don’t they provide a matching POH for their version? It’s pretty confusing but without it, you’re on your own guessing which setup to use for flying.
I’ve seen there is a performance table on the glareshield if you flip it over, maybe that helps.

The JF PA3 is spot on for the numbers.

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His numbers are correct for the 1977 and later 200 HP Arrow, from the POH

~146 TAS at 75% performance cruise at 5000 ft. (125 KIAS)

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Personally, I would not expect that Carenado to be accurate. They make realistic looking aircraft, but that is about it. If you just want to get where you are going faster, fly the Carenado. Just don’t buy an Arrow III IRL :smile:.

Regarding the tables, what you first do is figure out the power setting you want to use; i.e. Economy Cruise 55% power 2500 RPM. At 4,000’ MSL, you should run 21.3" of manifold pressure at 2500 RPM. Then find the matching TAS table, draw a line from 4,000’ on the y-axis until you intersect the right temperature on the slant lines, then go straight down to get the book TAS. All of this assumes you have leaned the mixture as required by the chart (which in this example would be peak EGT). There are examples on the charts (see the text box and the corresponding dashed line) that aren’t too hard to follow.

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Who flies at economy cruise???

:wink:

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Apparently @GlitteryGecko5 if he is getting 108 KTAS :smile: !

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To be fair, with his settings, he got the book numbers with the Carenado but not the Just Flight. Yes, Carenado has a bad rap, but, bad rap does not translate to truth. Just what, umm, stuff people want to say.

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They are slightly different to the ones from the ODM provided by JustFlight, not sure why exactly. The FuelFlow is a bit higher and the KTAS are a bit lower on the JF one.

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It should be pointed out that @GlitteryGecko5 is nowhere near 75% performance cruise with his settings though. Even so, it is good to have the perf on the later model year.

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How do you know without knowing the OAT?
I also don’t see anything written about proper leaning which is crucial.

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Well, the manual was written before the SU3 update, and we don’t know if before or after the UK update, so that could account for some differences in performance from their own manual.

Their manual consists of real POH charts, so I don’t think it has changed with the Sim Update :wink: And since their Arrow follows exactly those charts for me, all is fine with the numbers.

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True, we don’t know if he was using real weather or chose clear skies, so the two flights could have been at different temperatures. But, it’s not likely that would account for that large a difference given he was only at 3500 ft.

Sorry, I thought you said the JF plane was off by the numbers in their own manual. Not owning the plane, I assumed they made their own chart or something by what you said.

I posted the sheet for performance cruise from a 1977 PA28R-201. And then you said the ODM provided by JustFlight.

JF is spot on to their ODM and that contains charts from a real POH as far as I know.

Here’s one example matching to the setup of the TO, depending on the OAT the expected KTAS are in the red range (based on the JF data provided by him). It’s 100rpm less, but his setup simply doesn’t match any of the suggested cruise setups.

Reaching the values of the Carenado with this chart would mean he’d have an OAT of >50°C.
Either Carenado is far off or they simply have entirely different performance.
Without a proper POH from Carenado, you won’t know.

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So, I have the Carenado version. I’ve only flown it once though when it first came out. Interestingly Carenado erased their own documentation when they updated the plane today. Fortunately, I had backed up the plane when I bought it, so I still have the documentation.

Is that the picture from the JustFlight manual? Or did you just take a partial screen grab? It’s missing a lot of the text from the actual POH page. It looks the same as one of the pages from the Carenado performance numbers, which match the POH from a 1995 or later Arrow. But it’s missing the titles.
Economy Cruise 55% Power and a similar title on the Y-axis.

Yep, from the ODM. It’s the economy cruise chart. They cut it out as well, it’s just a summary of the charts.
The section is titled Economy cruise (55% power – 2,200 RPM).

I just meant JustFlight cut the titles off their pages, Carenado didn’t.

But now, Carenado just deleted all their manuals, haha, unless they put them somewhere else, I can’t find them now, and the directory titled “Documentation” where they usually put it is empty.