Book speeds

JustinD

JustinD

Line Up and Wait
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JustinD
I was reading another thread where someone was mentioning book speeds. This got me wondering, how is your bird compared to the book?

My 182, which I've done no modifications on, runs about 5 knots faster than book speeds for any given power/weight/temperature/altitude combo, while still burning the same as the book says it will for that combination. What does yours do? Is it common for the planes to generally be at, faster, or slower than the book?
 
Mine is 20% faster then book, burns 20% less fuel and after its annual mechanics pay me. ;)

All jokes aside, basically right on book numbers, with stall speeds matching the Robertson supplement numbers.
 
On the numbers,actual fuel burn is close to advertised.
 
Book speeds?? The aircraft I did most of my training in had only the basic V-speeds. Whenever a student would ask what's cruise speed I'd shrug and say about 100kts. What's fuel burn at full power'? Uh somewhere in the neighborhood of 10gph?
 
I am 5kts slower then book down low (3-5k).

I think part of it is attributable to having a 3 blade Prop and Tip-Tanks. No other mods.

I am going to start doing a few things to try and get a few of those knots back.

Fuel burn is inline with book.

Flav
 
I would think the POH would have different numbers for tip tanks and the 3 blade prop, seems like a lot of stuff to put into the wind without making some new numbers.
 
My latest Cirrus performs right at book speeds, despite having every option (including some that add drag like FIKI and infrared camera). My previous SR22 outperformed book speeds by a little bit (3-4kts) but it was a naturally aspirated plane so it was still much slower than my current turbo plane.
 
When following the book RPM/MP settings - I get book numbers: 147KTS give or take. (I'll easily get over 150KTS in the winter and struggle to stay over 140KTS in the hot summer.) Funny how those old guys with slide rules got all the numbers spot on.

But the aircraft was certified with a less powerful engine than what I have. It will go faster! Yes, I tested it. No, I'm too chicken to do it again. I figure the guys with the slide rules got everything else right - - - I'm not smart enough to 2nd guess them.
 
JustinD said:
I was reading another thread where someone was mentioning book speeds. This got me wondering, how is your bird compared to the book?

My 182, which I've done no modifications on, runs about 5 knots faster than book speeds for any given power/weight/temperature/altitude combo, while still burning the same as the book says it will for that combination. What does yours do? Is it common for the planes to generally be at, faster, or slower than the book?
Click to expand...

How did you measure this? By reading IAS and converting to CAS and then to TAS? Your airspeed indicator is probably not accurate.

A couple years ago, I did a test of a 1968 Piper Arrow and measured true airspeed by the 3-way GPS method and the IAS->TAS method. Using the GPS method, the airplane was approximately 1 knot slower than the book cruise performance chart. Meanwhile, I discovered the airspeed indicator read about 8 knots too high.
 
dmspilot said:
How did you measure this? By reading IAS and converting to CAS and then to TAS? Your airspeed indicator is probably not accurate.

A couple years ago, I did a test of a 1968 Piper Arrow and measured true airspeed by the 3-way GPS method and the IAS->TAS method. Using the GPS method, the airplane was approximately 1 knot slower than the book cruise performance chart. Meanwhile, I discovered the airspeed indicator read about 8 knots too high.
Click to expand...

my bird is pretty new (2012) so i'd like to think my airspeed indicator is pretty accurate.... the gps gs (corrected for wind vs tas where applicable) , TAS, IAS, and so one would all agree with being faster than the book.
 
In the '50s and '60s, Pipers were winning a lot of handicap races like the Powder Puff Derby. Their book numbers, on which the handicaps were based, were usually more realistic than those of other manufacturers.
 
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