The International Cessna 170 Association

I am the new owner of a Cessna 170B (1952). I have been looking for a good reliable source for V Speeds for this airplane. Most sources agree within 1 MPH of so, but when it comes to Vx and Vy, there are as many answers as there are sources. The Vy is mostly agreed to be around 88 MPH, but I have seen Vx speeds from 62MPH to 76 MPH. Does anybody have a indisputable source? Thanks in advance.

As a new pilot, I went thru this same exercise when I bought my 170.
Mainly because flight instructors drill into our heads the V-Speed are in some way gospel.
From the Owners Manual (not approved data) I derived:
Vs0 52
Vs1 58
Vy 88
Vx 62
Vfe 100
Vne 160

I then flew the airplane and never used them again.

The only V Speed of any real consequence is Vne and that's painted on the dial.

Va is going to be in the ball park of Vfe (top of white). I believe the useful thing about Va is that the wing will stall of a 2G load is applied - thus keeping you well within structural limits.

If you're looking at your airspeed indicator avoid stalling, you're doing it wrong.

Vy/Vx mean nothing IMO as they change based on aircraft weight and atmospheric conditions. I climb out between 70 or 80. If it feels like it will climb more, I raise the nose.

Another note, the manual says to fly 70mph on final approach but I find 60mph to be a better speed.

Also, how old is your ASI and when was the last time it was calibrated or the pitot tube shape verified?
These will have a big impact on what you see on the dial as well.

You'll be much more comfortable if you fly the airplane by feel and not worry about the ASI.

Hi All,

I see this is an old thread on a much discussed subject. I would be interested in anyone's opinion on the attached document in which I have attempted to compile information on the "V" speeds for this aircraft. I have included the references.

Fire away.

Thanks,

Bob

Moderator: removed original attachment as updated PDF is attached in later thread

Looks good.

I see two Vy entries.

Thanks,

Regarding Vy I labelled 2 different items as "Vy":

In the Owner's Manual Operating Details, the "CLIMB" section states the "best climb speed" range from SL to 7000' is 85 to 78 MPH indicated airspeed. It also says see climb performance chart in section V.

The chart in section V gives "best climb speed TIAS" with a range from 89 to 79 from SL to 7000'. These seem to be both describing what we call Vy and referring to the same thing but the speed ranges are not exactly the same. The section V speeds are included in the Airplane Flight Manual which is official documentation.

Either I am missing a distinction or the CLIMB section is just not that precise...

Bob

Bob,

The book refers to “Normal Climb” which may not be the same as Vx or Vy, both of which have narrowly defined technical aeronautical meanings. Normal climb as I understand it is more of an operating recommendation where you don’t need Vx or Vy to optimize rate of climb or to clear an obstacle. In this case, normal climb would be a climb rate that’s somewhere between Vy and cruise speed that gives a reasonable cruise climb coupled with adequate cooling, visibility over the nose, etc, etc.

There is some reason we are all bit confused about Vx, Vy, and Normal Rate of Climb. Here are the relevant parts from the Owners Manual.

Reference to Normal Climb
Unambiguous reference to Best Rate Additional reference to Best Rate

Hi Pete,

Thank you for the information; these are the sources I was referencing but I forgot where the 88 speed came from, and as you say it unequivocally says best rate of climb.

I have tweaked my list:
Bob