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Discussion in 'Flight Following' started by Arnold, Jul 30, 2020.
No wind o you fly your final approach speed based on 1.3 Vso?
For a normal landing (not a short field) I fly the recommended POH approach speed,which is indeed around 1.3 Vso. If you fly faster than the POH recommended speed in a no-wind condition you are asking for trouble.
Ha...the poll results are backwards. You don't have to watch many landings at a busy local airport to observe that about 25% of pilots fly 1.3Vso, and 75% fly faster...and nearly float out of sight down the runway before they touch down.
It depends on the plane. My 182 has a Sportsman STOL, VGs and a big 3 blade prop. My true VSO is under 50 knots. I can fly at 1.3 VSO on final, but it feels way too slow and if I’m shooting an approach it takes forever. I usually shoot for 85 - 90 knots on final then pull power and drop the last notch of flaps on short final. The 3 blade prop seems to slow me down very quickly and I’m over the numbers at around 55 - 60 knots. This seems to work well for me in my plane. Other (stock) planes I have flown I always shoot for 1.3 VSO if I’m coming in with full flaps on a normal landing.
What's the diff 'twixt wind and no wind? None. (if it's not gusty anyway)
if it's gusty then add 50% of the delta WS to your approach speed.
yes, with every plane I've flown so far. maybe an extra 5 knots in the t-tail lance, otherwise I'm starting with 1.3.
I do in my Arrow. And I also adjust 1.3 x Vso for weight. 1.3 x Vso with full flaps at gross weight is approx 82mph and I usually cross the threshold at 75mph at the weights I typically fly.
Yes thereabouts. I usually shoot for 65kts down final in the Archer which is just slightly above 1.3x Vso.
Good landings are slow landings.
1.3Vso in my plane is 69kts, and that's fine grossed up, light, I like to come in slower. Light, no wind/no turb, I've come in as slow as 60kts short final. Especially if it's short field or I'm practicing short field. Even at 69kts, the Mooney can have significant float when light. So, it depends.
EDIT: But, I will not ever come in faster than 70kts, unless the gust is at least 10 or better.
Way more people think they are doing this, than are actually doing his.
If you don't account for the weight of the airplane you aren't at 1.3 Vs0
I just bought a plane and over the past few days have been experimenting in the pattern with various speeds and power settings for decent rates, short final speeds, etc. I settled on 69-70 (use 70 as an easy upper visual) short final. Guess what Vso is...69.
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I fly my approach at 75-80 MPH in the Navion. This is a nice number as it gives margin over stall and is well below the gear and flap speeds. Vso is 51 MPH indicated or 54 "true indicated" (what they called calibrated back then). 1.3 Vso would be about 70 MPH (after converting to True Indicated and back) but it varies higher depending on whether the power is on or off.
1.3 Vso works pretty well for me on a not-too-windy day. An exception would be landing at a large busy airport, where I fly much faster on final and bleed off speed before touchdown - knowing the first high-speed turn-off is going to be 4,000 feet or further from the threshold anyway.
In the Luscombe 8A Vso = 45 mph in un-accelerated fight. 1.3 x 45 mph = 58.5. I normally fly final at 65 mph at max weight. At 60 the controls are getting a bit mushier than I like. Short field I'll use 60.
No wind? In tune with the airplane? Back side of the power curve at 1.1 works well if I'm light. My loaded weight has as much to do with landing speed as wind does. How current I am in that airplane? Even more.
Yep, the Navion only needs 850 with no wind. Margy landed at IAD once in a pretty stiff headwind and got stopped and turned off in the width of the entrance taxiway. Confused the hell out of ground control when she called them. Now I figure if I can't make the turn at my house (about 2000' down the runway) without getting on the brakes, I've messed something up.
Yes, it does, right until the engine quits. That's a benefit of going a bit faster - more energy gives you more options in case of an engine failure.
in a 172, no faster than 60 knots inside a half mile. If it’s light, say just me and less than half tanks, 55. In the RV-8, 62 knots. I usually keep it fairly tight and roll wings level on final at a quarter mile. At our airpark, if it’s straight in, I keep the speed up, do an overhead break (140-150 at the break, power to idle, 45 degree bank turn, continuous turn to final) and roll out on final inside a quarter mile at 62.
Depends on the plane. In my Cessna 140 or son in laws 172 1.3 or maybe a little slower over the fence works well, but then I round it out and stall it at the surface. The Mooney is a much different kettle of fish. I carry that much to just above the surface and bleed it off until it gets to stall speed. If I bring it in too slow I run out of lift and it can get to a point where you just can’t Slow the descent. Different wing.
Not sure if Stewart is doing the math or not but many people likely don't understand that 1.3 VS0 IS 1.1 VS0 when lightly loaded in many planes...my last one for example:
I almost always flew power off approaches. Trimmed for 80 mph abeam the numbers with 10* flaps and that typically put me at 67 to 69 over the fence with full (40*) flaps.
1.3 or 1.31 Whatever it takes.
Well, it did say "based on"
It's not so much 1.1 Vs0 as that published Vs0 is a max gross weight and like other load-based speeds, decreases as weight decreases, so 1.3 times it decreases as well.
My current problem is a G3X Touch doesn't register speed under 20 MPH so I really don't know what my short final and landing speed is much of the time. Fun problem to have.
Yes, but my factory manual does not account for it. Instead, it says:
"To allow for a safe margin above stall speed throughout approach, hold airspeed above 90 MPH until flaps are lowered."
"On final, trim the aircraft to fly hands-off at an approach speed of about 80 MPH."
And that's it.
Ummm...I think that's what my spreadsheet shows...
I've been looking to try back side of the power curve approaches, but only 110 hrs in the ship it will require more min. control speed flight time to be comfortable enough.
1.3 is about the minimum the C-172 manual recommends.
Vs (flaps up) = 47 kias, manual recommends 60-70kt approach speed (1.27-1.48Vs)
Vso (full flaps) = 41kias, manual recommends 55-65kt approach speed (1.34-1.58Vso)
I suspect the range of speeds Cessna recommends is based on weight of the airplane, you can approach slower when it lighter.
My normal approach is 65-70kts (65 +5/-0) with 10-20degrees flaps and power off.
Ya almost lost me there Tim.
I think what you are saying is that fully loaded in your example 1.3 VS0 is 62 *1.3= 80 mph, where as lightly loaded 1.3 VS0 is 54 *1.3 = 70 mph, so ipso facto 1.1*62 = 68 mph which is close enough for this example to 70 mph. So I do get what you are saying.
In the SR-22 I typically fly 85 knots on vfr final, slowing to 79 knots basically over the fence. this is done with about 15% power during the descent. Power stays in until runway assured, then back it out. The pull the power too soon and the sink rate increases drastically, get too slow on final (below 79 knots ) and sink rate increases drastically. Not a big deal if it happens if you react correctly, but you need to be aware of it. Because of that big expensive engine out front, long periods gliding at idle is discouraged unless practicing engine out, so I rarely do power off approaches. Since I rent, 3,000 feet is my shortest runway now days, so loading differences are that big of a worry.
The relation between IAS and CAS is highly nonlinear in the slow speed range, so 30% above indicated stall speed might be only 20% above the calibrated stall speed. In other words, if you are using 1.3x indicated airspeed, you are flying a lot slower than you think.
In my STOL C-150, I flew power on, full flaps at 1.0 Vso.
That was a guess, anyway, because my airspeed indicator was near zero...
There was plenty of reserve energy at the bottom of the approach and control authority was good. Once the power came off for touchdown, there wasn't much left and I usually stopped on the numbers and taxied off on the approach end of the runway...
It probably does. But that's 1.3 Vs0 adjusted for weight, not 1.1 Vs0 as a target.
It depends. In the Citation yes, Cessna 340 no. At 1.3 in the C340 we are about 30K below blue line.
Never really understood this one. What’s the .3 for in the first place, if not as a buffer for things like wind gusts?
For my plane it's 57 * 0.3 = 17. Unless a gust of 17 mph stops instantly, which ain't gonna happen in any weather I'm flying in, then I'm fine.
I voted yes as I've discovered that it results in a smoother and more stabilized landing for me. The planes I rent have checklists provided and the owner or whoever creates the checklist seems to add 5-10 mph to the final speed when considering the published Vso. Example, the Cherokee has a published Vso of 52 mph but they have 75 on final. I typically fly 65 on final. I also know that if I'm in a full flap setting doing slow flight I can typically get her down to about 49 mph before I get stall warning and 47ish before she actually stalls. I know, I know stalls are dependent on AOA but that wasn't the question. The Cessna 172's that they rent also have 75 as the final on the checklist and if I fly 75 on final I have to be very gentle on the roundout or I'll end up with a heck of a balloon. I've started using 65 on final in the 172 as well and the balloon can still happen but is less likely to happen. Imagine that, less speed, less energy to dissipate and things go better.
It was the other way around in my C182A. See spreadsheet in post 23. And I would think this is more typical because of the higher AoA @ slow speeds and the pitot being aligned for cruise speed.
A factor of 1.3 gives you enough energy to flare for a smooth touchdown, without being so fast as to float down the runway.
Sure, it can also be a buffer for sudden wind gusts, but it can't achieve both at the same time.
When are you transitioning below blue line then?
Plus a little for grandma, seeing as though none of us are perfect at holding a speed.
With the exception of EdFred of course.