Nose stays high on landing (+ BA route question)

[martinlest2 58]

On touchdown, the nose remains in the air and the front gear only makes contact with the runway below about 80kts. Any idea what could be wrong? The approach and touchdown (at around 170kts, as per the PSS manual) are fine otherwise. I brake manually and engines reverse but even pushing the stick right forward I can't get the nosewheel down on the ground much above 80kts. The CG is fine....  Suggestions welcome.

 

One supplementary question (nothing to do with the above, but not worth a separate thread I think): BA ran a Concorde flight from Heathrow to Bahrain (and back!) for a while (if I am not mistaken). What would the route have been? Would it have been able to go supersonic at all? BA & AF were careful not to trail a sonic boom across land areas, but Heathrow to Bahrain is mostly over land of course. Any ideas what happened in this regard?

 

Thanks,

 

Martin

[FSMuseum 39]

Hey Martin,

I used to own the PSS bird, and loved it until SSTSIM came around. Have you tried that? Suggest you look at it: http://www.sstsim.com

Anyway, on your main question, have you checked the pitch trim? If it's all the way to nose up then I think that's the issue.

And on your supplementary, if you give me your email through PM I can send you the route they used, it did briefly make supersonic during the flight.

Chris

[Ray Proudfoot 8,927]

Hi Martin,

 

To answer your second point first there is an excellent forum that holds all the routes Concorde used to fly. You can find the EGLL-OBBI-EGLL routes here. http://www.strontiumdog.plus.com/concfp.htm. It would fly sub-sonic until reaching the Adriatic at which point it could go above Mach 1. A special route over the sparsely populated middle east ensured it could stay at Mach 2 until ToD.

 

On your first point if the CoG is centred then the nose should come down naturally but having watched the ITVV Concorde video I notice the pilot does push the stick fully forward once the nose wheel has touched the runway. Perhaps you could post a screenshot at touchdown in case it highlights anything.

[martinlest2 58]

Chris.. I love the PSS plane and wouldn't want to change it, though I gather the SSTSIM one is even better.

 

Yes, I see that in the video too Ray, but I would imagine that my PSS a/c is behaving very unrealistically in not having its nosewheel touch the ground before, in fact, 65KIAS this afternoon (given that I land at 170kts). If I wait till all wheels are in contact with the tarmac before I brake, I risk running out of runway!

 

Anyway, I'll check the trim - but do I in fact (I ask myself as I write this) know what you mean? Where do I check the trim? Probably obvious when I go back to the plane and I am going to kick myself for making myself look an idiot - but .... I set ELECTRIC TRIM to ON before take-off, but what else? Not the Datum Adjust... I've gone blank. The CoG is dead-centre, as I say....

 

Thanks too for the link to strontiumdog - I had totally forgotten that I have the site bookmarked already in fact!

 

Martin

[FSMuseum 39]

Do you leave the autopilot on? It's known that when this happens, and one forces the nose down, the autopilot compensates with trim, that may be the issue, as when you force the nose down on landing, the autopilot wants trim, keeping the nose up without any issues on approach.

[martinlest2 58]

No, I turn F/D, A/Thr and A/P off once the rear wheels are on the ground at the latest

[Ray Proudfoot 8,927]

Try turning A/T and AP off at 1,000ft and fly the landing manually. Trim is worth checking especially as Concorde has no flaps and trim may be outside normal limits if you leave the A.P engaged. It should normally stay around zero.

 

I agree with Chris that the SSTSIM version is more accurate but the PSS one is still pretty good.

[martinlest2 58]

Yes, I think that the trim is too high. The CoG indicator shows just under 53% (and the marker is dead centre between the orange limit bugs). Is that a bit high at landing? I use the VFE... so it should be correct. If it were lower though the nose would be heavier..

 

I am not sure how to gauge that trim is around zero. There's a trim wheel of course but where do I read the trim in Concorde? I thought that the CoG indicator was the Concorde equivalent of the trim gauge.

Of course I can always trim with the button programmed for the purpose into my Saitek X52! Not very real, but it does seem to help.

Martin

[martinlest2 58]

A BIT LATER! ....

 

Something is really wrong. I have trimmed right down with the X52 as I land but even at 90kts, if I stop pushing the yoke forward and let it come back to its natural position, the nose gear comes off the ground again. The plane almost seems to want to take off! This is VERY annoying. I am sure this didn't happen last time I flew Concorde (several months back)....

[pschlute 37]

53%  COG is fine for landing. The COG is governed by the fuel distribution.  The pitch trim is entirely separate and controls the default position of the elevons. In the same way you need to have correct pitch trim in a subsonic jetliner through the elevator pitch trim, the Concorde needs to have correct pitch trim for the elevons (it does not have an elevator). The indicator is on the throttle pedestal.

 

Can you do a normal landing with A/P off at say 1000 feet ?  You should only have A/P on below this point if you are doing a full autoland.

 

Also , how much fuel do you have when you are landing ?

 

Peter

[martinlest2 58]

Thanks... I think I know the theory OK... trim, elevons etc. I just watched the ITVV DVDs again so I should be reasonably clued up on Concorde by this stage. That said, not sure how I missed the trim gauge on the pedestal!! It's the usual place - I looked for it. Going blind and/or stupid, I guess!!

 

Even so, I just can't work out why the nose wants to remain in the sky when I land. I have had the PSS plane for years and I don't remember ever having this issue before..

 

I think I need to run an entire flight to look at this - setting up a saved flight 10 miles from touchdown doesn't really work (although the pss file is good, and the a/c loads fine - though I can't engage LAND when I start a flight in that way).

 

I am going to fly Heathrow to Bahrain now and will report back. I have a total of 57% fuel on this flight. For NY I have about 90%. Maybe I am landing with too much fuel?? But I'll go through a few flights before I post back, noting fuel, CoG, trim etc as I come in to land..

[pschlute 37]

Your best bet is to do a proper flight from start to finish, without saving it.

 

If you were trying to land with a full load of fuel you would be creating all sorts of problems.

[martinlest2 58]

Yes, as I said, I am flying EGLL to OBBI at the moment. No, I didn't try to land with a full load of fuel  :rolleyes:  AutoSave and the .pss file between them save flights pretty accurately, but not enough to test this out, I agree.

 

Will report back later! 

 

M.

[Mike777 163]

Is it possible you inadvertently switched FDEs at some point?  This seems to me to be an FDE problem.  I never owned the PSS Concorde and haven't flown any Concordes for a long time, but this problem does sound familiar using some of the many free FDEs out there.

 

I also recall a problem where the aircraft rotated around a different point than its main gear due to a reference point error in the aircraft.cfg file.

 

Mike

[martinlest2 58]

I wondered that, but I really don't think so. I'll install the aircraft again from the CD-ROM on another PC with FS9 though and compare., just in case.