AX2000 Landing Flare

[uuoret]

2 of us have an AX2000, with a 582 engine, flying as sweet as a nut. We have noticed, however, that occasionally landing in still air with the throttle fully back, we are having a somewhat solid landing on all 3 wheels, the stick being back against the stops, but no flare...weights and balance seem to be well inside the envelope...

I suspect that with the low engine revs, (<2000), there may be a prop windmilling/disturbed airflow effect on the elevator. All approaches are generally flown at 55 - 60 mph.

There are times when the aircraft is quite heavy (2 up with as much fuel to the weight/balance limit) and we get a lovely flare - greasers - when there is slight power on for the landing and/or 10 mph of wind.

Has anyone else noticed this?

Any help greatly appreciated.

J :confused::confused:

[dublinpilot]

Is it simply a cast of landing at too slow an IAS? Would flying with slightly more speed give you increased elevator authority just when you need it?

Worth a try.

[Pace]

Hi there are probably people here who know the type well who will come in advice you.

Just in curiousity what is she like stalling and what speeds are you getting the stall in different configs?

Pace

[uuoret]

Hi - thanks for your replies so far.

IAS at the point of flare is 55 MPH (should be plenty for a flare).

Stall with two up and fuel is 38 MPH, one up is 35 MPH.

Noticed a significant port wing drop when we deliberately stalled last week. :bored:

If the prop is below the revs required to produce thrust of say 55 MPH whilst landing, will this slow prop effect "mask" elevator responsiveness by slowing and/or disturbing the airflow over the top of the centre section?

My syndicate partner says that the prop will still produce thrust, even when idling, but I know this thrust only kicks out about an 18 MPH airstream - hence my theory of masking......

Many thanks,

John

[Genghis the Engineer]

I while since I flew one, and certainly my instinct would have been to use the sort of approach speed you are but I'd guess that in practice you are using a slightly over-slow approach speed.

You're flying with a fairly forward CG, which reduces elevator authority. Also, the AX2000 is very draggy - particularly induced drag in the roundout. This is pretty typical of microlights of the era - the Thruster, Spectrum, MW6..., all have similar characteristics.

I think I'd try flying a heavy AX2000 with a rather higher approach speed than you're using - say around 65mph. This won't add much to the landing distance because, so long as you keep the stick back through the landing roll, the induced drag will be huge and you'll still stop very quickly - but it should ensure that you get a proper 2-wheel roundout and flare. (I used to have a Spectrum which was very similar to this.)

G

[Pace]

Stall with two up and fuel is 38 MPH, one up is 35 MPH.

uuoret

38 Mph in the stall should give a reference speed of rounding up 50mph. 55-60 Mph should be more than adequate.

Genghis mentioned that the aircraft is very draggy so it could be that although you are holding the correct speed that you are flairing fairly high allowing the speed to bleed off quickly below the ref speed?

It is worth one of you watching the speed on touchdown and noting that.

At altitude set the aircraft up for landing and see if you are still getting a lack of elevator authority where you can play with it a bit.

Pace

[chevvron]

No experience of 2000 but plenty of landings in AX3's. Used to fly final at 50 mph ias and had no problems like you mention.

[Genghis the Engineer]

Just a thought - have you checked the elevator deflections available against the TADS?

Also PACE has a very good point - how high are you initiating roundout? I'd have thought that anything much above about 10ft is probably too high.

G

[vihai]

If you are able to bring it to a stall in flight (are you?), with the same configuration, you should be able to do the same in the flare.

[uuoret]

Thanks for all your input, chaps. FYI, the TADS are completely adhered to, rounding out at between 5 and 10 feet, but she just goes "straight through" and touches down on all 3 with a bit of a bang....!

We'll certainly try to simulate a landing at height - the stall comes on well, which indicates a flare, but of course the trottle is never fully back, so it will be interesting to see what happens.

The other detail is that we generally don't use the trimmer - I wonder if we trimmed back for landing any difference would be made?

Thanks again for your input!

John :):)

[Pace]

The other detail is that we generally don't use the trimmer - I wonder if we trimmed back for landing any difference would be made?

That maybe your answer "incorrect trimming" There are many aircraft where landing on all three and porpoising down the runway is caused by incorrect trim.
Try and trim back till you need positive forward pressure to hold your descent profile.

When you come to flair there will be no heavy feeling on the stick/column

Pace

[Them thar hills]

IMHO I wouldn't be abusing the trimmer.
If you trim for your initial approach speed, then fly the rest of the way in purely on the stick.
Holding off too high is quite common, often when a pilot has been used to flying a heavier, larger aircraft with more inertia.
The AX is a low energy draggy machine, so a high roundout and flare will rob you of elevator power just when you need it, especially if the CG is in limits but forward.
:)

[Runaway Gun]

I've not flown the AX2000, but here's my twenty pence worth...

If the stick is back on the stops, you are probably in or very close to the stall, regardless of your airspeed.

Sometimes a little extra speed down late finals will help with elevator authority in the flare. For example 65kts in the Jabiru flare was great, anything below 60kts was asking for the Earth to swallow you up....

As per this link....
Full page fax print (http://209.85.229.132/search?q=cache:ZdpaQXhZsq0J:www.pmaviation.co.uk/admin/upload_pdf/AX2000AX2000.PDF+AX2000+flight+airspeed&cd=4&hl=en&ct=clnk&gl=uk)

For an engine failure it suggests:
To increase elevator control in the final flare, where practical increase
the speed to 55 - 60 mph just before the round out

For landing:
To start the descent, reduce the throttle
setting and establish an airspeed of 55 mph. In windy conditions increase this approach speed to 60 mph. Set the
trim accordingly

I also believe in safely trimming as late into finals as is permissable...

[chevvron]

I'm no expert on the AX2000, but I would have thought that even a 5 ft flare is a bit high; I used to 'demonstrate' flare at 'about 2ft and it lands itself'; cos at this sort of height you're just about in ground effect and it sinks to the ground quite gently.

[GOLF_BRAVO_ZULU]

Genghis the Engineer. Just a thought; don’t those types benefit from having the ailerons rigged with a significant “up” deflection, ie mainplane reflex? If that was insufficient, wouldn’t that make pitch up sluggish and the stall twitchy?

[Genghis the Engineer]

I'm no expert on the AX2000, but I would have thought that even a 5 ft flare is a bit high; I used to 'demonstrate' flare at 'about 2ft and it lands itself'; cos at this sort of height you're just about in ground effect and it sinks to the ground quite gently.


I think that perhaps somebody is confusing roundout and flare. An aircraft in this class probably rounds out starting around 10ft, and flares around 18 inches.

G

[Genghis the Engineer]

Genghis the Engineer. Just a thought; don’t those types benefit from having the ailerons rigged with a significant “up” deflection, ie mainplane reflex? If that was insufficient, wouldn’t that make pitch up sluggish and the stall twitchy?

The X'Air certainly does, which is a very similar wing - and both aeroplanes are derived from the AX3. Looking in the TADS (http://www.bmaa.org/upload/techdocs/2005392034480.BM53_9%20Cyclone%20AX2000.pdf) the ailerons are just shown as ±24° but there's an asterisk next to that figure which doesn't seem to correspond to anything. I wonder if there's a correct "ailerons neutral" setting angle being missed here.

That said, it's the other way around - ailerons-up gives reduced elevator authority, which the (otherwise far too twitchy) X'Air needs. If the ailerons are too reflexed upwards, then it's possible that an aeroplane doesn't have enough elevator authority. So, drooping the ailerons a bit may well fix the problem on this aeroplane?

G

[uuoret]

Guys, this is all good stuff - we'll be looking at all of the suggestions this weekend - and I'll let you know what does and what doesn't work.

I'd be grateful for any more views, so keep 'em coming!

J

[Genghis the Engineer]

If all else fails, please shout. I'm a BMAA inspector and check pilot, and was involved in the X'Air certification and testing of a few subsequent examples. Hopefully that gives me some small skills in the fine art of finding out why microlights are going odd things.

G

[uuoret]

Thanks Ghengis - could you possibly PM me with a mobile number? I'll give you a call over the weekend. Top of the list for investigation is the ailerons and I'd like to speak to you about that.

Many thanks again,

John

[uuoret]

Thanks to everyone who threw in their tuppenceworth!. We tried a variety of configurations on Saturday morning, and have concluded that the ailerons need some droop, although all "arrivals" that day were perfectly normal (10kt wind straight down the r/w, and leaving just a little power on, rather than throttling right back).

Happy flying, chaps!

[2hotwot]

uuoret
I think I would do a quick calculation of the C of G to make sure that it is not too far forward in the configuration you are using

[uuoret]

Good point - we have however checked the C of G, weights and balance and are happy with the outcome.

Cheers,

J :ok:

[avidian]

I have spent the summer flying an AX2000 and it does tend to plant itself in three pointer mode unless firmly flared ( compared to the AX3 which has the closest to autoland in the microlight world !) .

The low pod coaming also seems to create the sensation of a big flare when in fact it is quite modest.

It is only about speed -60mph (or a bit more on a windy day) is good. If you are not getting a good flare fly it a bit faster ( the asi may not be spot on). The extra pace is not a problem as Genghis mentioned - the 2k is so draggy she stops in a few yards after touchdown. A little touch of power in the flare can help too.

Have a look at
YouTube - Microlight Cyclone AX2000 G MZFX (http://www.youtube.com/watch?v=iO2sl_mpTMk)

By the way, after 30 very enjoyable hours over the summer I have to report that the AX2000 is a well kept secret - an economical and brilliant fun aircraft - even better than my old Spectrum ! Have fun !

Avidian

[Genghis the Engineer]

Ah now I have to disagree with you there Avidian - the Spectrum was a truly wonderful little aeroplane that I'd love to fly again (plus it doesn't have the seat structure bars of the AXs that stick into my shoulder blades).

Nothing against the AX3/2000, but the Spectrum will always be one of my favourites - a real shame so few were built and even less are still flyable.

G

[S-Works]

G-MZFX - Ha! I did my Microlight rating in that aircraft and the AX3 G-MYYL!!!!

What a small world.

[avidian]

Ghengis - yes maybe you are right, but nostalgia is not what it used to be :) - the accommodation in the Speccie was great - but I did have some tricky hot days (porker in the back, 503 single carb ) when most of the flight was conducted at a height where involuntary collecting of firewood was a distinct possibility. Solo - no problem. I would still have it now if I could have found a hangar wide enough ! Still, I racked up a good 150 hours !

Bose- x : 4000+ hours and still going strong ( mind you, she has consumed a few engines !)

Best regards Avidian