During some flight training in my 172, an instructor told me that Cessna designed their trim systems in such a manner that if the plane were trimmed full-up, the aircraft would be set up very close for best glide.
This appears to be the case for my plane. However this should not be relied upon as exact, as weights, c.g.'s, etc change with time..
Know the numbers, but in an emergency this may help.

In Cessna singles, Best Glide seems to halfway between Vx and Vy -
Not Necessarily so for other aircraft.

0.01
Ken

From a level flight attitude.
Slow the plane  down and trim full nose up and then one nuckle nose down.
This will be pretty close.

Hi Will

The POH for my 1968 C150H shows the following :

Va - 73mph
Vx - 57mph
Vs - 55mph
Vso - 49mpg @ 20deg flaps
Vbg - 65mph

Hope this helps narrow it down.

Vin

Will,

I consulted my Owner’s Manual (I have 5 copies) for the 1966 Cessna 150F.  In section 5 (Operational Data) page 5-5 there is a chart titled  “Maximum Glide."  The conditions stated in the chart are: Speed 65 MPH (IAS), propeller windmilling, flaps up, and zero wind.  Please consult your Owner’s Manual for the “E” Model, there is likely a difference between the swept and box tailed models.

John   C-150F   Plymouth, MI

Thanks,
     I will try it at 65 mph IA, the next time I have a chance.  Unfortunately, the copy of the owners manual I have for the Cessna 1965 Model 150 does not have that in there.  This is an "E" model, with the straight tail, and perhaps the figures could be a little different between the E and F, especially with the tail configuration, but I'm going to go with 65 to start and try a little up and down, watching my VSI.
Thanks to all.
Will

Will,

Regarding “Rules of Thumb” and the Owner’s Manual and Operating Handbooks.  I would always go with the manufacturer’s data.  The term “best climb” is not specific enough.

As stated in the Owner’s Manual for the Cessna 1966 150F: The “best rate of climb” (Vy) is listed at 72 MPH at sea level.  The “best angle of climb” (Vx) is listed at 52 MPH.  (Section 2, Description and Operating Details, page 2-8.”  I have just located an Owner’s Manual for the 1965 Cessna 150E.  The listed airspeeds are the same, and are incidentally located on the same page.  Unfortunately the 1965 Owner’s Manual is less complete than the 1966 Owner’s Manual.  And as you had previously noted that there is no Glide chart included in the 1965 Owner’s Manual. 

While reviewing the manuals, differences were discovered such as the dimensions and the gas valve handle location for the “On” position.  However, and for what it is worth, all of the air speeds that I looked at were the same with the exception that I could not locate a best glide speed.  I would start with a call to Cessna.  This model should have some certification documents required by the FAA that would include the best glide. 

Please keep us informed. 

Best wishes,  John McAuliffe

Thanks everybody for the information about the best glide rate for the C-150-E.
I finally heard back from Cessna, and their tech checked their data and advised "69 MPH IAS" as the best glide for that plane.
Again, thanks to everyone.
Will