I was looking through my Owner's Manual today (yeah -- not a good day to fly...) and couldn't find a Vx or Vy speed. Looked in the HUGE (smile) "Approved Flight Manual" and couldn't find them either. I have some notes from when I bought my airplane that Vx is 62 and Vy is 88. The only references in the Owner's manual are (in Section III) for a "Minimum Run Take-Off" which states to maintain 62 MPH (Flaps 20) "until obstacle is cleared". Then in Section V it lists a 76 MPH Flaps up speed / 67 MPH with flaps 20 in the "Performance Information" chart. In the same chart in Section V the "Best Climb Speed TIAS" is listed as 89 at SL decreasing to 79 MPH at 7,000 feet. Section III says: "the best climb speed range from sea level to 7,000 feet is 85 to 78 MPH indicated speed", but notes you should see Section V for climb performance!
Now, in case you're wondering, I'm not some extremely anal guy that has to fly within a half a knot of whatever speed. Heck, if I can maintain +/- 5 I'm doing VERY well! I usually climb out around 85 - 90 MPH. But I've been thinking about reinstating my (long expired) CFI, and I can just see the examiner asking me for these speeds...
N8287A wrote:I was looking through my Owner's Manual today (yeah -- not a good day to fly...) and couldn't find a Vx or Vy speed. Looked in the HUGE (smile) "Approved Flight Manual" and couldn't find them either. I have some notes from when I bought my airplane that Vx is 62 and Vy is 88. The only references in the Owner's manual are (in Section III) for a "Minimum Run Take-Off" which states to maintain 62 MPH (Flaps 20) "until obstacle is cleared". Then in Section V it lists a 76 MPH Flaps up speed / 67 MPH with flaps 20 in the "Performance Information" chart. In the same chart in Section V the "Best Climb Speed TIAS" is listed as 89 at SL decreasing to 79 MPH at 7,000 feet. Section III says: "the best climb speed range from sea level to 7,000 feet is 85 to 78 MPH indicated speed", but notes you should see Section V for climb performance!
Now, in case you're wondering, I'm not some extremely anal guy that has to fly within a half a knot of whatever speed. Heck, if I can maintain +/- 5 I'm doing VERY well! I usually climb out around 85 - 90 MPH. But I've been thinking about reinstating my (long expired) CFI, and I can just see the examiner asking me for these speeds...
Why am I so confused?
You're in the correct section of the Owners Manual....the only problem is the OM is not APPROVED data! (And under it's certification rules Vx and Vy were not required data to be specified.)
However...the exact same data IS contained on the second page of the AFM and of course that document IS approved data! (76 mph flaps up/67 flaps 20 for obstacle clearance and 89 mph SL/standard day for optimum climb.)
Tell/Show your examiner that you know this information, and show him what the "best available" data is...and let him live with it! There's no requirement for an applicant to produce data that was never required by the type design rules in order to pass a Practical Test. (And keep in mind that modern aircraft, when publishing a Vy does so referencing a standard atmosphere, therefore the 89 is most closely aligned with that specification.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Thanks, George, for your realistic answer! I always appreciate and respect your replies.
Cheers,
Stan
You're in the correct section of the Owners Manual....the only problem is the OM is not APPROVED data! (And under it's certification rules Vx and Vy were not required data to be specified.)
However...the exact same data IS contained on the second page of the AFM and of course that document IS approved data! (76 mph flaps up/67 flaps 20 for obstacle clearance and 89 mph SL/standard day for optimum climb.)
Tell/Show your examiner that you know this information, and show him what the "best available" data is...and let him live with it! There's no requirement for an applicant to produce data that was never required by the type design rules in order to pass a Practical Test. (And keep in mind that modern aircraft, when publishing a Vy does so referencing a standard atmosphere, therefore the 89 is most closely aligned with that specification.) [/quote]
What about us jokers with an O-360 and a c/s prop? I've always kinda assumed that these speeds would be the same, but looking at the AFM, it has slightly different Best Climb Speeds for the McCauley and Sensenich propellers. So I'm guessin that my best climb speed would be a little different, but not by a whole lot. Dang modified airplanes!
What about us jokers with an O-360 and a c/s prop? I've always kinda assumed that these speeds would be the same, but looking at the AFM, it has slightly different Best Climb Speeds for the McCauley and Sensenich propellers. So I'm guessin that my best climb speed would be a little different, but not by a whole lot. Dang modified airplanes!
Quite right! The additional horsepower would allow you to utilize a slightly slower IAS for optimum on obstacle-clearance climb (probably only about 3-5% difference)...but the same speeds published for the original airplane would apply for best rate climbs and power-off glides.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Doesn't the STC for your conversion have to include this data, since I imagine some test flying was done during the approval process. A 172 I flew with a Penn Yann engine STC included a bunch of interesting takeoff and landing performance that looked like it was right out of the modern AFM/POH, but it was definitely data collected specifically for that conversion, which also included a gross weight increase. If it's not required, maybe this case was just a courtesy.
Hi there,
as to Rudys (aparently toung in cheek question bout glide angle) every aircraft isn't rigged the same, an old instructor I had (who's dad had a pilot's licance singed by Orvil Wright ) said wings level power off you have best glide for your aircraft.
brad
bradbrady wrote:Hi there,
as to Rudys (aparently toung in cheek question bout glide angle) every aircraft isn't rigged the same, an old instructor I had (who's dad had a pilot's licance singed by Orvil Wright ) said wings level power off you have best glide for your aircraft.
brad
Would that be true of "us jokers" with the O-360 Lyc too
Seriously and with no test data I did notice a big difference from the continental in takeoff and climb with one notch of flaps (10 degrees) at about 65mph. The extra power allowed an incredibly different and very solid climb with 10 degrees. The C-145 didn't seem to climb very well with 10 degrees and 65 mph although it would come off the ground a bit quicker than no flaps. Most of my operations I look for 80 to 85 mph standard climb though.
The Avcon STC #SA806CE states:
"NOTE: With the described engine and propeller installation, performance will be at least equal to, or better than, that given in the original FAA Approved Flight Manuals for the Cessna 170A and 170B airplanes."
Cessna® is a registered trademark of Textron Aviation, Inc. The International Cessna® 170 Association is an independent owners/operators association dedicated to C170 aircraft and early O-300-powered C172s. We are not affiliated with Cessna® or Textron Aviation, Inc. in any way.
