Telemaster 40E Lands better in winds w/o Flaps?

[N9DP]

At takeoff time wind measured 8.6 mph max; at landing wind was 10.5 mph max. I measured it with my Kestrel anemometer held about 7 feet above the ground in the clear. Wind was out of the NE.

At about 250 feet altitude the TM40E had nearly a zero ground speed – the wind must have been at least 25 mph up there, assuming I was flying at about 1.3 x Vs. The winds aloft forecast was for 15 knots at 3000 feet, but I suspect this was greatly in error – many times it is.

I decided to land when the wind came up about 14 minutes into my flight. With the wind out of the NE, the approach is much more difficult because it is over high trees and the effective “runway length” is reduced because of landing over 100 foot high obstructions. Landing other directions provides a clear approach over prairie grass and is much easier.

I had practiced several low approaches with flaps up and had decided I could have gotten the plane on the ground safely. When the wind speed increased, I deployed flaps (about 30 degrees) and added six clicks of down trim, as I usually do in preparation for landing.

But the plane was very squirrelly with the flaps down, and I had a few close calls due to mechanical turbulence near the trees. I got the plane down ok, but I think I would have done better without flaps in this situation. Group members agree?

Good landings,

Dennis

PS: I apologize for posting this to the Modeling Science Group, but the reality is that the really knowledgeable guys seem to hang our here, as opposed to the (name withheld to protect the innocent) group where the posting probably rightfully belongs.

[Pull-Up]

Does your TM40 have the dedicated inner flaps, or does it use the outer ailerons as flaps (via radio programming and dual servos) ?

If the outer ailerons are used as flaps, the wings will experience tip stall sooner.

I have read that many experienced TM fliers prefer no flaps with the TM. The TM does not gain much (if anything at all) from flaps. I have exprimented with this on the simulator (Telemaster in RealFlight 4.0). The simulator clearly showed that the TM lands better (more stable) with no flaps. Flaps might be slower by a mph or two mph, but comes at the high risk of tip stalls. From this testing on the sim, I decided to build my TM with no flaps. The TM lands ridicoluisly slow even without flaps. Plus without flaps, it lands very stable. With flaps, tip stalls are produced easily.

[vintage1]

Yup. Flaps reduce stall speed, but at te expense of drag and i not inboard flaps, at the expense of a much more marked stall characteristics.

I remember coming in on one of the roughest landings ever in a commercial airliner, the only time I have ever landed on the NE/SW runway at Heathrow. Winds were in the 50-70 knot range allegedly - force 9 IIRC.

After landing and a pause to loosen stiffened muscles, I looked out at the other planes coming in. Big jets were landing with half flap or less. They had all traded off airspeed which they didn't need to reduce, for better stall characteristics.

Flaps it seems are really there only to slow the aircraft down to make sure it doesn't burst tyres on landing, or overrun the runway. With enough headwind, they are more trouble than they are worth.

On takeoff, they merely ensure that the aircraft, in a limited space, can get up to a lower flying speed quicker. Again in windy conditions, they may not be needed.

[MCarlton]

I think people sometimes get the wrong idea about flaps. They are not brakes, and are not really there to slow you down as such.

The principal benefit of flaps to my mind is that they allow a steeper landing approach without exceeding a normal landing speed. Thats important on a slippery aircraft which might otherwise need a very long and very flat approach to get there.

Inboard flaps are a great deal better than full span if used for this purpose, as on landing, the large increase in camber inboard creates the same effect as washout and stops the tips going stally stally first.

A lot of aircraft which carry a lot of flap (like a Fiesler Storch) utilise the drag as a brake when on the ground, especially into a headwind, wheel brakes are not that much use on slippery wet grass, snow, mud or other things which STOL aircraft have to contend with.

One nice little foible of flaps is that if you flare just above the ground, the aircraft can become a quite effective WIGE machine and just not settle to the ground, so sometimes, pulling the flaps back in at the moment of flare out can be useful.

On your approach in the wind, deploying flaps will just increase drag and airspeed and thus make the model more susceptible to gusts and turbulence.

Remember that sometimes, it is worth opening the throttle a crack or two more than normal to "carry" the drag of the flaps until right over the threshold.

Matt

[vintage1]

I think people sometimes get the wrong idea about flaps. They are not brakes, and are not really there to slow you down as such.



The most ceratainly act as brakes, and allow a considerable reduction in stall speed.

The principal benefit of flaps to my mind is that they allow a steeper landing approach

as does any airbrake that increases drag


without exceeding a normal landing speed.

whilst allowing a lower than normal landing speed.

Thats important on a slippery aircraft which might otherwise need a very long and very flat approach to get there.

Inboard flaps are a great deal better than full span if used for this purpose, as on landing, the large increase in camber inboard creates the same effect as washout and stops the tips going stally stally first.

A lot of aircraft which carry a lot of flap (like a Fiesler Storch) utilise the drag as a brake when on the ground, especially into a headwind, wheel brakes are not that much use on slippery wet grass, snow, mud or other things which STOL aircraft have to contend with.

One nice little foible of flaps is that if you flare just above the ground, the aircraft can become a quite effective WIGE machine and just not settle to the ground, so sometimes, pulling the flaps back in at the moment of flare out can be useful.

On your approach in the wind, deploying flaps will just increase drag and airspeed



reduce airspeed actually

and thus make the model more susceptible to gusts and turbulence.

Remember that sometimes, it is worth opening the throttle a crack or two more than normal to "carry" the drag of the flaps until right over the threshold.

Matt

[richard hanson]

No one mentioned it -- but flaps allow the drag and lift to INCREASE without changing the angle of the fuselage (and tail group and wing panels )
This allows the craft to REMAIN at a lower angle to line of flight -
---- you fill in the rest ------

[N9DP]

Does your TM40 have the dedicated inner flaps, or does it use the outer ailerons as flaps (via radio programming and dual servos) ?

If the outer ailerons are used as flaps, the wings will experience tip stall sooner.

I have read that many experienced TM fliers prefer no flaps with the TM. The TM does not gain much (if anything at all) from flaps. I have exprimented with this on the simulator (Telemaster in RealFlight 4.0). The simulator clearly showed that the TM lands better (more stable) with no flaps. Flaps might be slower by a mph or two mph, but comes at the high risk of tip stalls. From this testing on the sim, I decided to build my TM with no flaps. The TM lands ridicoluisly slow even without flaps. Plus without flaps, it lands very stable. With flaps, tip stalls are produced easily.

Hi Pull-Up,

You might want to consider using the inboard flaps as I did. If you have a really big flying field, 250 to 300 feet of “runway” with clear approaches, you may not need them. I flew the TM40E for five flights w/o flaps deployed for landing (I hadn’t yet explored the degree of pitch-up accompanying flap deployment) and last five with thirty degrees of flaps deployed. With the exception of the last very windy landing, the flaps allowed a fully stabilized approach at reduced speed and greatly reduced the landing distance. In my book, the flaps contribute markedly to a good landing.
____________________
To quote from the Frank Granelli review of the TM40E:
http://www.masportaviator.com/pdfs/Telemaster%20Electric%20Article%20Text.pdf
“But the wing flaps added to the airplane’s appeal. The extra wing lift the flaps provided allowed the Telemaster to land at less than 10 mph. Having flaps also expanded the number of airfields the big aircraft could use. With full flaps and in a full sideslip, the Senior Telemaster could descend almost vertically into a small, tree-lined field without gaining airspeed. Even from several hundred feet up, it is possible to land the Telemaster in about 50 feet of runway using only about 100 ft. of clear approach space. A new pilot should never consider doing this, but an experienced one can accomplish this, if necessary, by slipping the flapped Telemaster.
______________________

I suspect that the added stability you experience with the simulator is a result of significantly higher landing speed. If you have sufficient runway this is not a problem.

The inboard flaps actually ensure that the stall progresses from the root outboard, the preferred stall progression. If flap deployment is inducing tip stalls, something is amiss in the simulator parameters.

The calculated no-flaps stall speed of my TM40E is 18.9 mph and approach-to-landing speed is 24.6 mph (using 1.3 x Vs) for my 18.5 oz/sqft wing loading. I use the approximate formula Vs = 4.4 (wing loading in oz/sqft)^0.5. I don’t know how much the stall speed is reduced with flap deployment, but to me it seems quite significant.

My experience in landing my TM40E w/o flaps is that it floats for a long ways and getting it down in less than 250 feet with a clear approach is difficult. Perhaps this is due to my carrying excess speed on final– I’d rather float a ways than stall out. I’m also pretty much of a beginner. But I also think the TM40E experiences ground effect, high-wing configuration notwithstanding.

Good landings,

Dennis

[Pull-Up]

N9DP,

Thanks for the suggestion.

All is fine with the simulator. The TM in the sim was using the full length aileron as flaps (as opposed to inner-only flaps).

I learned from the sim to get the TM at near stall speed before making a landing approach. Seems to work great in the virtual world, and I will see later after I finishing building my real one. Thanks for the helpful suggestion however, and I will keep it in mind.

[eflightray]

If your using a simulator to trial something, don't forget to alter wind directions, (it's never straight down the runway), also if the sim has it, add in turbulence/gusts, (again the wind in real life is never without them).

Flying a sim without the 'real world' effects is often too easy.

[vintage1]

Too right.

Try first of all landing at 100 ft..throttle back and slow the plane right down into wind, watch it wobble in the breeze..after a couple of mild stalls you know how slow you dare take it. Then do the same again a bit lower, then a few touch and goes, then land it.

THE most important thing to learn with a plane is to fly it slow and land it. Everything else can wait.

[Al M]

Don't use them for a cross wind landing. I did once. It seemed like everything stalled out, wings,stab,rudder, and prop! Increasing throttle quickly rolls the plane over.

[N9DP]

If your using a simulator to trial something, don't forget to alter wind directions, (it's never straight down the runway), also if the sim has it, add in turbulence/gusts, (again the wind in real life is never without them).

Flying a sim without the 'real world' effects is often too easy.

Thanks for the tip! I increased all of the zero values of wind and turbulence parameters in RealFlight 3.5 and my mild-mannered Spectra became a real handful. So realistic as to be frightening.

Reminds me of a ATP friend who told of an 847 sim ride depicting two-engines out and smoke in the cockpit while low over LA. The captain had a panic attack and the FO had to abort the sim for fear the guy was going to collapse.

Good landings,

Dennis

[richard hanson]

Flaps on the big Telemaster are really not necessary-Ihave flown them -Not the sims -
But using inboard flaps as I mentioned earlier - allows the fuselage to remain at a lower angle - this is important -as control remains better - the closer the stab is to direction (angle )of flight .
(nobody learned that one in school?) this is also true in spins ( look up NASA studies if you still doubt me)
anyway the Telemaster - with HUGE inboard flaps could be setup for extreme approach angles.
OR with lots of thrust on hand -it could be hovered in --like this -- this is not a trick photo it is simply a demo of vectored flight
Guess I killed this thread-------

[MCarlton]

The most ceratainly act as brakes, and allow a considerable reduction in stall speed

Agreed that they ACT as brakes, but what I was getting at was that whereas Airbrakes per se are designed to purely add drag, part, at least, of the function of flaps is to increase lift by increasing camber. I agree that flaps act in a pure braking mode if flap movement is high (eg full size Hurricane/Spitfire et al). I always assumed that part at least of the slowing function was done by the increase in induced drag as a result of increased camber?

Hence the decrease in stall speed compared to "airbrakes" in a traditional sense.

Personally, I think if a flap has, say, 90 degrees or thereabouts of movement, then it stops being a flap and becomes a trailing edge airbrake.

What I was getting at was that there is an assumption that the function of flaps when landing is purely an increase in parasitic drag and that deploying flaps works in the same way as applying the brakes on a car and that therefore all one has to do is come into land at any old speed and attitude, deploy the flaps and the model will instantly slow to a crawl without any other effects on its handling and flight characteristics.

Maybe I am wrong, I am prepared to admit that :)

On your approach in the wind, deploying flaps will just increase drag and airspeed

That there is a typo, I don't actually think flaps increase airspeed...

I think perhaps my unscientific way of putting things gets in the way of my intentions

Matt