4 bounced landings in a row

[ArtVandelay]

No way would I try to fly the final at 1.1Vso, only 6 mph margin for error: instrument error, wind shear, pilot error...POH uses 1.3, that's what I use. 1.2 if short field and winds relatively benign. I also add 50% to my POH landing distance as a margin of error.

[Shadrach]

7 hours ago, teejayevans said:

No way would I try to fly the final at 1.1Vso, only 6 mph margin for error: instrument error, wind shear, pilot error...POH uses 1.3, that's what I use. 1.2 if short field and winds relatively benign. I also add 50% to my POH landing distance as a margin of error.

1.1 is the ballpark; a better way of saying it is that I slow beyond 1.2 for about the last 200ft of altitude and that is in a steep descent with the wing unloaded and power off. It is essentially setting up a rapid but controlled sink rate and arresting it with a single smooth elevator pull that goes full aft just before touchdown. Ground effect also provides a cushion. Hand on throttle and vernier friction lock loose!

I would never fly into what I consider a short field unless conditions were ideal. Who would land at 1700ft strip if windshear was a threat?

Edited January 18, 2016 by Shadrach

[Shadrach]

On January 18, 2016 at 3:57 AM, teejayevans said:

No way would I try to fly the final at 1.1Vso, only 6 mph margin for error: instrument error, wind shear, pilot error...POH uses 1.3, that's what I use. 1.2 if short field and winds relatively benign. I also add 50% to my POH landing distance as a margin of error.

 I cut this from the 1965 M20E POH.  Mooney believed that 10 mph above stall was reasonable for standard power off approaches under some conditions. It seems they did not provide a short field recommendation in 1965...

10mph above stall in an E model is 1.175*Vso at gross weight.  I have seen people on this board recommend 1.3 Vso with a touch of power, even speed numbers with no consideration made for weight. Half flaps, no flaps, some flaps.  We have met the enemy and he is...

Edited January 19, 2016 by Shadrach

[midlifeflyer]

14 hours ago, Shadrach said:

True that it is based on CAS, but at approach speed I think the difference is insignificant (1-3kts). Especially if the aircraft is power off by short final.

Yup might be true. But it varies and without checking you don't know.

[mike20papa]

I have one better for you..in my old A model manual..it prescribes the method of putting the airplane up on jacks by getting one of your AP buddies to crawl under one end of the wing, position his back under the spar and raise up till you can get a saw horse under the prescribed jack point.  Then (and it doesn't say how many beers later)..get him to crawl under the other side of the wing and repeat the process.  Then you use a rope wrap around the prop (and a shade tree I guess) to hold the nose up....

'

I like that picture above.. so do you use that AOA?!...If I squint hard enough..I can just barely see Bill Wheat in the pilot's seat.

[Shadrach]

10 minutes ago, midlifeflyer said:

Yup might be true. But it varies and without checking you don't know.

I did. It's under 3 mph in my F and when power off the IAS is less than CAS, as in you have additional margin.

[Bob_Belville]

20 hours ago, midlifeflyer said:

Are you sure?  You might be right but the reason I ask is many people (all aircraft types)  make the mistake of thinking this is based on IAS and wind up with too high a number. It's not. It's based on CAS.  IOW, the calculation is 1.3 X Vso CAS. They you use the conversion table to convert the result to IAS.

And, even at IAS... looking at an old M20C manual I have hanging around, it shows full flap (i.e., the landing configration)  stall speed of 57 mph. That gives me a 1.3 Vso of 74, not 83, even without converting.

I found CAS/IAS conversion charts for M20J on line but I don't think I've ever seen similar for our old M20Es. Can someone point me to same? Is it the case that the factors that make the difference are the same for all planes of the same model? Specifically, would "instrument and position errors" change if a new ASI is installed? How about a new panel? I have both. I think "position error" is limited to the static port. Is that true?

[Shadrach]

52 minutes ago, Bob_Belville said:

I found CAS/IAS conversion charts for M20J on line but I don't think I've ever seen similar for our old M20Es. Can someone point me to same? Is it the case that the factors that make the difference are the same for all planes of the same model? Specifically, would "instrument and position errors" change if a new ASI is installed? How about a new panel? I have both. I think "position error" is limited to the static port. Is that true?

For an F model, but likely close enough.

[Bob_Belville]

9 minutes ago, Shadrach said:

For an F model, but likely close enough.

Ross, thanks for the charts. That first one is not included in our older model owners (sic) manuals and is the only one that compares IAS and CAS. 

• The stall speeds in the bottom left chart are IAS per the footnote. Not CAS.
• The top left chart starts at 65 mph, above the full flap stall speed. And it appears that at 65 MPH, full flaps, zero bank, the IAS is between CAS no power and CAS power! 
• And finally, the footnote in the top chart, an ASI has an acceptable (im)precision of +/- 2.5 mph which is a greater than the difference between CAS and IAS!

I conclude that for the speeds in the landing range the subtlety of IAS vs CAS can be ignored. But it well might be worthwhile to do some stall work and compare your particular plane to the book speeds at gross and light, w&w/o flaps, w&w/o power. Those comparisons will be more useful.

Or just install an AOA. 

[DXB]

Here's IAS vs CAS for my C model- appears in '68 POH.  The disparity between the two is just a tad greater for the short body it would appear.   

[Bob_Belville]

Just now, DXB said:

Here's IAS vs CAS for my C model- appears in '68 POH.  The disparity between the two is just a tad greater for the short body it would appear.   

Thanks! I note that at stall/landing speeds (70 & 80 mph on the chart), full flaps, the difference is 1 mph, less than the allowed ASI error.

It does indicate that at cruise speeds IAS is 3 or 4 mph high. I assume my GTN 750 uses IAS to calculate TAS so it would read correspondingly high. 

[Marauder]

Interesting stuff. Even more interesting since our Aspens actually give you a number to look at. I know my mechanical ASI and Aspens (both of them) are dead nuts on for IAS.

It appears they just added the knots data to the 1975 F charts in my POH. They match Shadrach what he posted.

I wonder how much affect mods have on all this?

Sent from my iPad using Tapatalk

[N201MKTurbo]

When I was young and foolish (I've owned a Mooney sense I was 26) I was out exploring slow flight. I was flying around with the top of the air speed needle on the top edge of the white arc. 1/2 a needles width above stall. I was seeing what power it took to maintain that speed, which is a lot more then you would think. I was practicing turns, climbs and descents. After about an hour of this foolishness I was feeling pretty confident, so I decided to try landing at this speed. I descended to pattern altitude, flew a pattern from the 45 and landed. The landing was VERY SHORT! The rollout was about 200 ft.

In retrospect I was very close to killing myself and I never did it again, but if you are crazy you can fly a Mooney approach below 60 KTS.

[Shadrach]

31 minutes ago, N201MKTurbo said:

you can fly a Mooney approach below 60 MPH.

FIFY.

Edited January 18, 2016 by Shadrach

[Shadrach]

53 minutes ago, Marauder said:

I wonder how much affect mods have on all this?

Sent from my iPad using Tapatalk

Likely not much. VGs may make a small difference.

[N201MKTurbo]

3 minutes ago, Shadrach said:

FIFY.

Huh?

I thought I was clear with my writing...

[MyNameIsNobody]

I think his reply was pretty clear.  Just be creative with the acronym...

[EDNR-Cruiser]

Gents,

I would recommend to ignore the subtle difference between IAS and CAS completely... - there is a place for it but not during approach, with usually shifting winds, gusts and all the other nice effects of low altitude turbulences...
What is much more important is to understand the effect of weight (or mass) on the required approach speed of our birds!
At full MTOW (which will never happen because we burn fuel during roll-up and take-off) the full flap stall speed of a M20F is 62 mph! Fine! Never try to fly THAT slow during an approach at MTOW though... - common sense.
However, when the tanks are almost empty and we fly alone the total weight goes down a lot and all of a sudden the stall speed goes down as well... - and with my Mooney it is now just 53 mph!!! Multiplied by 1.3 is still just 69 mph! This is a huge difference to MTOW speeds!

I invite you to try it out... - based on total weight of your plane, the fuel onboard (as little as comfortable) and your individual "gross weight" your M20F should stall somewhere between 51 and 55 mph!

The runway of my home airfield is a comfortable 2.000ft long and when I stick to my weight & balance calculations (including the stall speed based on todays weight), I have no problems to vacate the runway at the 1/2 marker with minimum fuel, I do not even have to brake hard. This would be impossible though, if I always flew the same approach speed as if at MTWO. 

Edited January 18, 2016 by EDNR-Cruiser

[Shadrach]

1 hour ago, N201MKTurbo said:

Huh?

I thought I was clear with my writing...

I quoted you but changed KTS to MPH in the post because a light Mooney will fly along at well under 60KTS (it'll do that at gross), it will fly at 60MPH.

Edited January 18, 2016 by Shadrach

[N201MKTurbo]

Sure it will, but have you ever flown a complete landing patern at less then 60 KTS?

If I recall that day the wind was blowing real hard, I went out to see if I could get my DME speed down to zero, or even go backwards. I only got it down to 5 KTS. This was done over what is now Front Range airport outside of Denver at 8500 ft. pointed at the Denver VOR north of Stapelton Airport. The wind was very steady with no bumps.

[midlifeflyer]

10 hours ago, EDNR-Cruiser said:

Gents,

I would recommend to ignore the subtle difference between IAS and CAS completely... - there is a place for it but not during approach

Even with an aircraft that has a large difference between IAS and CAS plus a significant weight-based difference in Vs0, the place to determine appropriate Vref is not during an approach.

The important part is to know those things exist and when and how to use them.