Without doubt the 747 is the best aircraft ever built

 

 

In the early days most jet aircraft were configured in the landing configuration by the outer marker and flew the whole final approach at VREF+ an additive. As fuel became more expensive airlines adopted low drag approach techniques which consisted of delaying selection of both the landing gear down and the landing flap position. Typically the landing gear is lowered anywhere from 2000 to 1000 ft and the engines spooled up in the landing configuration by 1000 to 500 ft.

 

I know that's your opinion. But you should say so. There are plenty who would very much disagree.

 

When you say early days about when are you referring? The a/c in my avatar for example started commercial service in the 60's and only flew the glideslope part of the approach with gear down. Very little difference between now and then. It still depends on a/c type and PICs whims to when to exactly lower the gear. Especially at a busy airport like Heathrow ATC will slow you down to 160kts for most of the glideslope from about 8DME to 6DME for separation and most a/c wil need their gear down.

I have often seen late deployment of gear which makes the a/c more difficult to land precisely especially in breezy conditions as the airspeed is changing too rapidly. Again the a/c in the avatar would slow to Vat+(wind component/3) from about 6DME. This would bring it over the threshold at about 1deg nose up requiring very little flare. More than 5deg flare and you would float all the way to the stand!

I know that's your opinion. But you should say so. There are plenty who would very much disagree.

 

When you say early days about when are you referring? The a/c in my avatar for example started commercial service in the 60's and only flew the glideslope part of the approach with gear down. Very little difference between now and then. It still depends on a/c type and PICs whims to when to exactly lower the gear. Especially at a busy airport like Heathrow ATC will slow you down to 160kts for most of the glideslope from about 8DME to 6DME for separation and most a/c wil need their gear down.

I have often seen late deployment of gear which makes the a/c more difficult to land precisely especially in breezy conditions as the airspeed is changing too rapidly. Again the a/c in the avatar would slow to Vat+(wind component/3) from about 6DME. This would bring it over the threshold at about 1deg nose up requiring very little flare. More than 5deg flare and you would float all the way to the stand!

I think you are splitting hairs. As the outer marker is usually after glideslope intercept that is no different to being on the glideslope part of the approach, is it? In the "old days" the plateau style approach to the ILS was very widespread. These days it's much different. low cost airlines in particular are delaying gear extension as late as possible while satisfying stable approach criteria. All this is driven by fuel costs. They were also an issue in the 1970s fuel crisis and I remember Lufthansa adopting a constant descent approach at that time. Mainly to reduce noise but also to save fuel.

 

The 160 knots until 4 DME at Heathrow is a minimum, not a maximum. They aren't slowing you down to it, they are expecting you to stay above it. So the gear extension doesn't help, it might even make you set more thrust than you need.

The 160 knots until 4 DME at Heathrow is a minimum, not a maximum. They aren't slowing you down to it, they are expecting you to stay above it. So the gear extension doesn't help, it might even make you set more thrust than you need.

ATC say "Reduce speed to 160 kts until 6DME" I think the meaning is clear to most people who understand English. There is no reference to reduce speed to be more than 160 as you imply. What you say doesn't have sense if that were the case. You could have a/c at any speed therefore making a pigs ear of separation. "Reduce speed to x" is a clear unequivocal instruction I would say.

And your second point depends on a/c type. The VC10 for example will stay at 80ish%n2 all the way from 210kts until close of throttles at touch down regardless of flap settings and gear up or down.

ATC say "Reduce speed to 160 kts until 6DME" I think the meaning is clear to most people who understand English. There is no reference to reduce speed to be more than 160 as you imply. What you say doesn't have sense if that were the case. You could have a/c at any speed therefore making a pigs ear of separation. "Reduce speed to x" is a clear unequivocal instruction I would say.

And your second point depends on a/c type. The VC10 for example will stay at 80ish%n2 all the way from 210kts until close of throttles at touch down regardless of flap settings and gear up or down.

To be precise, and as a native I do understand English  :mad: , Heathrow speeds are as follows.

 

"180 kt on base leg/closing heading to final approach; between 180 kt and 160 kt when established on final approach and thereafter 160 kt to 4 DME."

 

At no point do you have to slow down to a maximum of 160. The maximum is 180.

 

As for the VC10, lovely machine that it was, it still had to obey the laws of aerodynamics. I can say with certainty that it would have required more thrust to maintain speed with gear extended than with gear retracted. The VC10 could not do as you said "regardless of flap setting or gear up or down". It would do as you described with flap and gear being extended appropriately as speed reduced from 210 to Vat. I've seen a 747 flown on approach in a similar way with the thrust levers not touched till flare. But you couldn't do it in busy airspace with ATC limiting your airspeed.

 

 

At no point do you have to slow down to a maximum of 160. The maximum is 180.

 

In fairness Kevin -- whilst I know what the AIP says the typical instruction (which overrides the advisory/planning information in the AIP) is "Maintain 160 knots to 4DME." The expectation if you have been given that is that you will fly 160kt as accurately as possible (and these days with Mode S if you have selected anything other than 160kt you would be getting a stern reminder). With the spacing at LHR regularly down to the wake turbulence minimum (and as little as 2.5NM on many occasions), having potentially 20kt speed differentials between aircraft would rapidly cause things to fall apart.

FSX ground effect can be controlled by air file tables 400 & 404. They have default values which devs rarely change probably because they either don't know or don't think it is important. Ground effect is quite different to ground rush which is dependant on perspective which in FSX isn't good.

Dropping the gear later is certainly true for airliners which I see coming into Manchester (EGCC) nowadays. Years ago (when there was only one runway at Manchester - 24/06 - or Ringway as everyone called it back in those days), you'd see all the older airliners such as 727s, Caravelles, DC-8, 707s, Tridents, TriStars, 111s, TU-154s, VC-10s Viscounts, Vanguards etc coming over Stockport town centre with their gear already down and locked as they hove into sight. These days it's not at all uncommon to see them coming into what is now 23R, passing over the town and then with about three miles to go that's when the gear starts coming down for many of them. 

 

Of course back then, there were a lot less decrees from on high to the pilots with regard to the minutiae of flying a jet, I know for example that lots of pilots would occasionally drop the gear on a descent from up high in order to slow the aircraft down, and pilots of some aircraft, especially the Dassault Mercure, would descend the thing like it was a jet fighter, which is hardly surprising for that one in particular, because it was designed like a jet fighter lol, which actually accounts for why it wasn't commercially successful.

 

 

While I enjoy a good 4 page discussion, this guy gets it right in the first reply.



FSX's ground effect is (way) overdone. It's why many of A2A's planes are more prone to floating with the slightest of pitch changes than their real life counterparts.



A lot of people getting really defensive about a flaw that isn't even arguable. It simply exists.

 

Great attention to detail, many don't get it because they don't have the real world experience to support their argument. I currently fly one of the most sleek jets out there with the Gulfstream 5/550 series. In the 5 you reduce to idle at 50ft and in the 550, you reduce to idle at 100ft all in order to lose speed. If you are not at idle by these points, guaranteed float. With a flaps 10 landing, you have to be at idle coming off the perch on downwind to go from 180 to landing speed by flare height. It's over powered and it's big wings loves ground effect. It's so sleek that you can make a 12 hour flight with less than full tanks(41,300 pounds). But, with it's high efficiency and loads of lift, crossing the threshold at VREF adding 2 degrees to the pitch at the 20ft call out and holding back pressure to keep the pitch constant will put me down at 1000ft which is the aim point. We even have a procedure called a MINIMUM RUNWAY LANDING. At 300ft agl, we shift aimpoint from 1000ft down to 500ft down. Pulling power at the proper height and adding 2 degrees at 20ft will put my mains down at 500ft like clock work. You can do this consistently day in and day out with the text book flare procedure. But, when you get in FSX, aircraft will flare by themselves with out you doing anything. You apply a text book flare and you are touching down at 2500ft.

 

I challenge developers to get this critical aspect of landing right. I'm a beta tester for IXEG and they have fully captured the landing performance. They engineered out the ground effect issue in Xplane. Thanks for your attention to detail Bonchie!   

 

 

Dropping the gear later is certainly true for airliners which I see coming into Manchester (EGCC) nowadays

 

Yeah, a lot of this has to do with noise also. A lot of places want you fast so that you transient noise sensitive areas quicker and they want you to delay configuration because they want you to transient noise sensitive areas with a lower power setting.

@Polizei

 

 

If we are talking strictly about planes the size of a 737 and bigger there are a few items that need amendment

1. Vref is definitely not the speed you want to have over the threshold at, it's at least Vref+5.

 

The aim is to cross the threshold at Vref+5 (Minimum!)

 

Not entirely true. All of the aircraft i've flown, to include heavies, have you cross the thresh at VREF. In fact, when I flew the DC-10-30, you crossed the thresh at REF and the touch down speed was REF- 5. There was a minimum touch down speed of REF-10 because you entered tail strike territory. The pilot not flying kept an eye on this speed.

 

Normally, there are 3 different speeds in landing. Approach speed(Vref+5), Threshold speed(Vref) and touch down speed(Vtd). In the DC10 performance manual, Vref charts were labeled threshold. It actually comes down to the type and how they do it.

Now, I do recall the DC-9-30 said minimum touch down speed was Vref+5 with the mains touching as you reached idle. I think it was due to the low power slow spooling engines. In the event you went around, you had a speed buffer while the engines spooled.

In fairness Kevin -- whilst I know what the AIP says the typical instruction (which overrides the advisory/planning information in the AIP) is "Maintain 160 knots to 4DME." The expectation if you have been given that is that you will fly 160kt as accurately as possible (and these days with Mode S if you have selected anything other than 160kt you would be getting a stern reminder). With the spacing at LHR regularly down to the wake turbulence minimum (and as little as 2.5NM on many occasions), having potentially 20kt speed differentials between aircraft would rapidly cause things to fall apart.

True, in the heat of the debate I got that backwards, it is a fly speed at instruction, not a minimum. However 160 is typically above Vref+5 so you will need less drag, not more, to maintain it. Hence it isn't an argument to get the gear down on the glideslope, contrary to what vololiberista stated, unless you are too fast at the intercept point. 

 

The procedure doesn't override the ATC instructions. If they want to give you leeway they'll say "at or above" in their instruction. You hear that often with altitude while crossing an IAP.

 

If they say "reduce speed to," they want you on that speed. They are telling you that most likely for separation reasons.

 

While I enjoy a good 4 page discussion, this guy gets it right in the first reply.

 

FSX's ground effect is (way) overdone. It's why many of A2A's planes are more prone to floating with the slightest of pitch changes than their real life counterparts.

 

A lot of people getting really defensive about a flaw that isn't even arguable. It simply exists.

But as I said in response to Rick's post, you can adjust the FSX ground effect. You can make it zero if you want. So it certainly is arguable.

FSX ground effect can be controlled by air file tables 400 & 404. They have default values which devs rarely change probably because they either don't know or don't think it is important. Ground effect is quite different to ground rush which is dependant on perspective which in FSX isn't good.

At least we can agree on this. 

 

True, in the heat of the debate I got that backwards, it is a fly speed at instruction, not a minimum. However 160 is typically above Vref+5 so you will need less drag, not more, to maintain it. Hence it isn't an argument to get the gear down on the glideslope, contrary to what vololiberista stated, unless you are too fast at the intercept point.

It depends on aircraft type doesn't it.  The VC10 for example had only 3 flap settings. Flaps 1 to fly at 180kts, flaps2 gear down at 160kts and full flaps for the landing. Some aircraft can put the gear down late some earlier. But in reality it depends on ATC instructions. You fly at the speeds they set and configure your aircraft accordingly. Some aircraft need to have the gear down early otherwise they will try to run away.  The 10 needed huge amounts of drag to stop it running away because of its high performance wings. Yet, it had probably one of the slowest touchdown speeds.

Whatever a/c you are flying you have to comply with ATCs speed instructions. The relevant manual will give recommendations as to flaps, thrust settings etc. As long as you comply with ATCs instructions within 5kts you're good to go.

 

 

But as I said in response to Rick's post, you can adjust the FSX ground effect.

You guys are 100% correct. Every aircraft in my inventory has record 400 adjusted, but unfortunately some don't know how to go about doing that. I tell guys to do what I do when flight testing. I get the manual and read the approach geometry section. I then fly the aircraft per the manual and perform the landing. If pitch is off, I know the flap lift needs some adjustment to get it right. Using text book flare procedures, the aircraft should touch down near your aim point. Long bodied aircraft may be 200 to 300 feet less than your aim point. If the aircraft stops sinking and start to float further from my aim point, ground effect needs adjustment. If i'm in a medium weight jet and I aim 1000ft down, im expecting a touch down 1000 to 1200ft down with a text book flare. In a long bodied heavy, i'm aiming 1500ft down and expecting 1200 to 1800ft down with a text book flare.

 

 

The DC/KC-10...NOW we are talking about high speed. E.g. minimum clean speed 294kts

Yep, but guys in the forum will argue that you can't fly above 250kts below 10,000ft even though my flight plan says"heavy". And the AFM says 250kts or minimum maneuver which ever is higher in the climb schedule below 10'000ft lol. I flew above 250kts in DC/KCs all over the world when departing heavy. Never been violated or questioned lol.

If the VC-10 had a high performance wing why was the fuel flow very much higher than e.g. on the first 707s (both cruising e.g. at M.84) ?

I always thought that the VC-10 wing was more designed for short runways instead of efficient cruise.

The VC10 had a "marginally" higher seat cost than the 707 by a few pence. But because it was more popular for passengers the actual cost was significantly lower as it was always full. Maintenance was lower because it was needed less and it was much cheaper than the 707 when it came to extend airframe life. Passengers would ask to fly on the 10 rather than the 707 if there was a choice. The then head of BOAC, Guthrie, did everything he could to bad mouth the aircraft. (he had made an agreement with Boeing for an exclusive Boeing fleet for BOAC). He was actually repremanded in Parliament for doing so. But by then his mouth had done the work and orders had dried up. China was very interested in buying but by then Vickers had destroyed the jigs and were starting the contruction of Concorde.

 

The VC10 had a high performance wing that was efficient at all speeds and altitudes. It was arbitarily limited to M 0.84/0.86 to preserve the airframe. It could easily fly faster and there were occasions when it did. When it entered RAF service they removed that restriction!!! It was the first T tail aircraft that was not able to deep stall (they tried!!). As you say the wing was designed for hot and high airfields. Probably the only a/c that coud take-off from El Alto with a full payload!! The benefit of that design is that at "normal" altitude airfields its performance was way ahead of others like the 707. The 10 would have taken of and already be at 1,000ft while the 707 was still on the ground. It is a very important aircraft in aviation history as there were many innovations that are still in use today and also subsequently used in Concorde.

http://www.vc10.net/Technical/wing_shapes.html

Thanks for your inputs guys.

 

Now lets go a bit harder with some crosswind:)

Up to 20 lnots its okzy i managed to decrab correctly but struggling up to 20knts.

 

Should you be fully aligned with the runway before touch down or your are allowed to decrab a bit after touch down. I noticed that when decrabing, the pitch increases slightly

 

@vololiberista

Must have been a wing every designer would be proud of even today if it's efficient during cruise and offers a good field performance.

Winglets are nothing new either! Vickers decided instead to put küchemann tips. Whereas the Handley Page Victor Bomber had them in the original design but they were dispensed with during the prototype production.