Help Explain: Best Possible Speed

[flyingcheesehead]

Like I said, I might give this a try when I redeliver my Mooney to the avionics guys so they can fix all the stuff they bolluxed. Hopefully they get it right this time. So, if I'm getting this right on short final (1 mile) I should be at cruising speed (160 mph), I cut power, do whatever I can to slow the airplane down, put down the gear (my best speed brake) at 120, flaps are 105, and I'm supposed to be doing 75 over the numbers.

OK, so the parameters so far (converted to Knots):


Plane.......Low Cruise...Vlo.........Vfe.........Vref.......Vs0
Kent........162?.........140.........110.........80.........59
Michael.....139..........104.........91..........65
Ed..........???..........???.........???.........??


I'm thinking I'll figure out power settings for each, fly an RNAV approach starting on autopilot for the sake of getting it stabilized exactly on a consistent glideslope, and then hand-fly when starting the gyrations a mile out - Mainly because my autopilot can't handle the gear and flaps at all, really - I get a pitch-up when putting the gear out, and a hard pitch down when extending flaps, and it takes my poor old analog KFC150 a while to figure out what on earth is going on. LOL

I might also try mine both with and without speed brakes, since I have 'em.

My main thought is my vintage Mooney has a much much smaller frontal area than Ed's Comanche. Hence Ed's aircraft maybe able to do something the Mooney simply can't. Never heard of a Comanche with speed brakes, lots of Mooneys have them.

The fuselage cross section is probably the biggest advantage the Comanche has on this test.

There are Comanches with speed brakes - Twin Comanches at least, and generally those STCs get developed for both the singles and twins. But there are certainly a much higher proportion of Mooneys with them than Comanches, where they're pretty rare.

A mile sounds about right, though I've never measured. But I don't start descending until I turn base, and then final. Pattern altitude is 1000 feet, and I can't imagine loosing more than a few hundred turning base to final. Moreover, I will be high enough that a lost engine will allow me to get to the runway.

OK, the reason I asked is that a standard 3-degree glideslope is 318 feet per nautical mile. 600 feet would be 5.67 degrees and 700 feet would be 6.62 degrees. I don't think you need to be nearly that high in a Mooney to make the runway if your engine quits. At those glide angles, you might be right that you can't bleed off nearly as much speed in a mile. Doesn't mean it can't be done, it just means that you need to do it at a more normal angle. After all, if you're coming in with lots of extra speed, you'll still have the energy to make the runway if it quits, it'll just be kinetic energy instead of potential energy.

 

[EdFred]

I was out at the airport committing acts of aviation with my A&P.

OK, to answer Kent's questions...
I do not cruise at 155KIAS (180mph), but that is right at the green/yellow arc for me, and if ATC is going to request best forward, that's what I am going to give them, because I am probably going to be in a descent. I could actually give them around 172KIAS (200ish mph) to about 1-1/4 out or so.
Landing gear Speed: 150 MPH
Flaps Speed: 125mph
Normal VFR pattern speed: 90-100mph indicated
Touchdown: 70-80mph indicated (at least that's the last time I look at the airspeed)
Vs0: 64mph

So here's what I did last night. I got on a 7 mile final and flew it to the bottom of the yellow arc. I was actually throttled back doing this. 24" MP maybe? I wasn't looking at the MP I just know I was throttled back. 2300 RPM on the prop. I loaded the GPS 30 approach, and when I was at the east tree line (just after the GPS read below 1.00nm to RWY30) I pulled power.
https://www.google.com/maps/@42.6549604,-85.3332284,1914m/data=!3m1!1e3

I put in as much right rudder as I could, I put in a bunch of left aileron, and I pulled the nose up until the speed bled to below 140MPH. I dropped the gear, kept the nose up, into the white arc, flaps to 27 degrees, and I kept that slip and attitude until I hit the west tree line. Half way between the west tree line and the river I let the slip come out. Since that sat photo was taken the numbers and displaced have been moved to the end of the runway. I put it down on the new number location. Google's measurement tool says I was 1.05 SM from the displaced when I pulled the power. I could NOT have made the runway even at the displaced had I not been nose high, and the side of my airplane becoming the front my my airplane. Not a chance.

Also, this whole challenge was based on an ILS/LPV approach, not something like 1000' AGL at a mile.

 

[tspear]

A Google search says Mooney has a12.7 to 1 glide ratio. Assuming my math still works, 1000ft vertical gives you 12,700 ft horizontal.
So pattern altitude gives you just over a two mile range.

Tim

 

[flyingcheesehead]

A Google search says Mooney has a12.7 to 1 glide ratio. Assuming my math still works, 1000ft vertical gives you 12,700 ft horizontal.
So pattern altitude gives you just over a two mile range.

12.7 to 1 glide ratio = 4.5 degree glideslope = 478 feet per mile. Granted, that's probably with the gear up, BUT...

My Mooney's (M20R) glide ratio is published at 11.2, but when I've tested it (granted, at idle, not dead) it has gone WAY beyond that.

A couple of examples:

Once, I started at 7500 feet and calculated the distance with the observed winds to just be able to make my home field. I pulled power that distance away, ended up soaring over the top of my field at 3000+ AGL, continued for 5 miles, turned around, came back and landed without adding power.

Another time, I put that 11.2 into ForeFlight, waited for the glide ring to hit the edge of the icon for my field on the chart. Again, coming from 7500 feet. The glide ring kept moving almost as fast as I was, so I dropped the gear at 6000 feet. Eventually I went to full flaps and speed brakes and went around the pattern for 28 instead of straight in to 36, and never added power.

So, I'm sure you're correct that 600+ AGL at a mile is more than necessary.

 

[flyingcheesehead]

So here's what I did last night. I got on a 7 mile final and flew it to the bottom of the yellow arc. I was actually throttled back doing this. 24" MP maybe? I wasn't looking at the MP I just know I was throttled back. 2300 RPM on the prop. I loaded the GPS 30 approach, and when I was at the east tree line (just after the GPS read below 1.00nm to RWY30) I pulled power.
https://www.google.com/maps/@42.6549604,-85.3332284,1914m/data=!3m1!1e3

I put in as much right rudder as I could, I put in a bunch of left aileron, and I pulled the nose up until the speed bled to below 140MPH. I dropped the gear, kept the nose up, into the white arc, flaps to 27 degrees, and I kept that slip and attitude until I hit the west tree line. Half way between the west tree line and the river I let the slip come out. Since that sat photo was taken the numbers and displaced have been moved to the end of the runway. I put it down on the new number location. Google's measurement tool says I was 1.05 SM from the displaced when I pulled the power. I could NOT have made the runway even at the displaced had I not been nose high, and the side of my airplane becoming the front my my airplane. Not a chance.

You're not making your point very well. I wouldn't do a slip just to give ATC another 10 seconds of best forward speed.

So, if you do this *without* a slip in the Comanche, how long does it take you to slow down? I know I could do it in a mile in the 182, but I'm not so sure about a slicker bird.

 

[midwestpa24]

For what its worth, the Comanche does have a slight advantage in its higher gear and flap operating speeds over the Mooney. Once you get the draggy things sticking out, it slows down in a hurry with power to idle.

 

[denverpilot]

For what its worth, the Comanche does have a slight advantage in its higher gear and flap operating speeds over the Mooney. Once you get the draggy things sticking out, it slows down in a hurry with power to idle.

Hey! That means the 182 wins all the time. It’s nothing BUT “draggy things”!

 

[EdFred]

You're not making your point very well. I wouldn't do a slip just to give ATC another 10 seconds of best forward speed.

So, if you do this *without* a slip in the Comanche, how long does it take you to slow down? I know I could do it in a mile in the 182, but I'm not so sure about a slicker bird.

Where did I ever say this was to be a Wile E Coyote Anvil approach from 3000' above pattern altitude a mile off the runway? Best forward speed means you're going into a towered field. Means you're probably on a long final. Means they want you at the numbers as soon as practicable. Also means you most likely have a glide slope to follow - whether it be the PAPI/VASI, an LPV, or an ILS. Best forward speed will always include descending during the final approach. No one is going to maintain n000'AGL until the numbers and then drop it on. Like you said, you're going to be 300'-400' a mile out. That's the initial premise I was operating from when I said steingar needed more training if he couldn't get his Mooney to slow down. Now if he was thinking he had to maintain 1500 or 2000 AGL until a mile out and then can it in, we were entering from two completely different points of view.

I actually had to do this once, OK I didn't *have* to, but the other option was get routed 5-6 miles out over the Atlantic going into St Augustine. Tower said if I can make best speed all the way to the numbers I am cleared to land, otherwise I have to get in trail behind a 7x7 on approach. I opted for the best speed to the numbers.

 

[flyingcheesehead]

Where did I ever say this was to be a Wile E Coyote Anvil approach from 3000' above pattern altitude a mile off the runway? Best forward speed means you're going into a towered field. Means you're probably on a long final. Means they want you at the numbers as soon as practicable. Also means you most likely have a glide slope to follow - whether it be the PAPI/VASI, an LPV, or an ILS. Best forward speed will always include descending during the final approach. No one is going to maintain n000'AGL until the numbers and then drop it on. Like you said, you're going to be 300'-400' a mile out. That's the initial premise I was operating from when I said steingar needed more training if he couldn't get his Mooney to slow down. Now if he was thinking he had to maintain 1500 or 2000 AGL until a mile out and then can it in, we were entering from two completely different points of view.

I actually had to do this once, OK I didn't *have* to, but the other option was get routed 5-6 miles out over the Atlantic going into St Augustine. Tower said if I can make best speed all the way to the numbers I am cleared to land, otherwise I have to get in trail behind a 7x7 on approach. I opted for the best speed to the numbers.

So, I don't know whose question you thought you were trying to answer there, but it wasn't mine that you quoted. I was asking how long it takes you to slow down without a slip. On the VASI/LPV/ILS/whatever. I wasn't asking about a manhole cover approach, and it doesn't say that in any of the text you quoted.

 

[EdFred]

I was quoting you. This whole thing started with steiny saying its impossible to slow a mooney down because they have a negative mu. Ok i exaggerate a little with the last part. My whole point was, yes you can slow it within a mile. Im going flying tonight I think. I will fly it to a mile before pulling power with no slipping and see what i get.

 

[flyingron]

I was in a pretty good descent showing 160 Knots heading into IAD in the Navion. They asked me how long I could keep it up. I told them until I hit the ground.

 

[EdFred]

Reference point number two. Got up tonight flew the lpv approach and did not slip, pulled the power at about the same place. It was hard to do it exactly the same place because I was on the other approach but same distance according to the GPS reading on the distance to the runway missed approach point. And not slipping I was still about hundred knots when I crossed the threshold maintaining the Glide slope in the Comanche.

 

[denverpilot]

Reference point number two. Got up tonight flew the lpv approach and did not slip, pulled the power at about the same place. It was hard to do it exactly the same place because I was on the other approach but same distance according to the GPS reading on the distance to the runway missed approach point. And not slipping I was still about hundred knots when I crossed the threshold maintaining the Glide slope in the Comanche.

What was the distance so we can try it elsewhere?