Air speeds

[dan carley]

I see all kinds of air speeds when someone is
Selling the plane some are so high it funny
Is that a selling point how do they figure the airspeed?

Danny carley

 

[JDeanda]

A Tale of Airspeed

Many moons ago a kit manufacturer had a presence on the local airport. One of the employees at this place talked about their airplane’s performance in, well, optimistic terms. If’n I recollect rightly, the claim was 214 kts with a 150 hp Lycoming. Pretty good for a slick two seater. One of the magazines came out to do an article on the airplane and test flew it themselves over a two way course. It averaged about 174 kts, which they reported, remarking dryly “I have no idea where the other 40 kts went.” Yeah, big egos in this business and the truth gets stretched a bit now and then.

 

[g zero]

Quick look on Flight Aware usually tells the real story

 

[rvbuilder2002]

And so many others state cruise speeds that are so low it is even more funny.

A lot of people have very little understanding about the Lyc. engine and its output power capabilities in regards to RPM, MP, and fuel flow.

It is very possible that the claims you see for high cruise speeds are from the minority that actually do understand. Particularly when it is rare to see speed claims that are much if any amount faster than the spec #’s published by Vans, and when you do it is usually because the builder went above and beyond a standard build.
In some cases the slower claimed speeds are for just the opposite reason…. The quality and accuracy of someone’s build fell short of the typical/standard.

 

[BobTurner]

This has been around forever. While the ‘errors’ are usually not large, I don’t think I’ve ever seen a normally certified production plane that can actually match POH speeds. The usual ‘explanations’ are, well, the test aircraft didn’t have antennas, rotating beacons, etc., adding drag.

 

[bjdecker]

Don't believe anything you hear, and half of what you see...

I don't believe anyone's description of an airplane's airspeed.

Show me an EFIS screen grab, so I can see all the performance parameters. Oh, and I want the output from the NTPS PEC spreadsheet (3 or 4 way GPS test)...

...but that's me

 

[Mel]

This has been around forever. While the ‘errors’ are usually not large, I don’t think I’ve ever seen a normally certified production plane that can actually match POH speeds. The usual ‘explanations’ are, well, the test aircraft didn’t have antennas, rotating beacons, etc., adding drag.

The only certified, production airplane that I've seen that came close to "book" speeds was my 1968 Mooney M20C. It was pretty darn close.

 

[BobTurner]

The only certified, production airplane that I've seen that came close to "book" speeds was my 1968 Mooney M20C. It was pretty darn close.

OTOH, my built-to-the-plans, by me (not the world’s greatest craftsman), RV-10, routinely matches Vans’ book speeds. I never stop smiling.

 

[Mel]

OTOH, my built-to-the-plans, by me (not the world’s greatest craftsman), RV-10, routinely matches Vans’ book speeds. I never stop smiling.

Oh, I agree completely. I was referring to your comment about "production" airplanes.