spoilers vs flaps

[blueair]

which is most useful for the sport flyer at a relatively small field, many thanks

[schrederman]

Spoilers increase airspeed when landing, flaps decrease airspeed when landing. My real glider lands like our models... 90 degrees of flap, and no spoilers...

Jack Womack

[kwmtrubrit]

I agree with Jack that both flaps and spoilers allow control over landing location. I've flown the full size sailplanes with spoilers, no flaps. Different method, same outcome. Jack has been in this hobby for a lot longer than I and I'm sure will give more input + or - to my following comment. I think it really depends on what model you are flying as to whether spoilers or flaps are best. Something that flies slowly like a Gentle Lady will benefit from spoilers more than flaps. Flaps will slow it down even more and could interfere with the control ability, or even cause a tip stall.

Keith

[GLIDERGIDER]

blueair:
If landing in a small space is desired, flaps is the answer. A full house wing is best. Ailerons up and flaps down. I've seen vary large and very heavy gliders slow down to a crawl on final approach and land inches from the pilots feet. Its an awesome sight to see. Down side of flaps is the complications of a 4 servo wing vs 2 servos and even one for spoiler system.

Dave

[Freakflyin]

Hey Blueair,
Definitely flaps for a small landing area. Dave's right though. You'll need sailplane software or enough mixes to be creative... and there's always y-harnesses... but that's cheating!
%^)

Mike

[blueair]

thanks guys, Im considering a challenger or maybe oly111 for my relatively short field, or both , I know I could do flaps and spoliers, im using basic 6 ch. radio, no computor type, really dont wish to go to much tech. Im wondering why more aircraft dont have spoilers, flaps seem more common except for sailplanes, but it sounds like flaps may be better option for me, will flaps drop you down as good as spoilers from strong thermal, many thanks for your input, oh, the field im using is about 140 ft, with few obstructions.

[DrFragnasty]

If you have a computer radio that can mix a 4-servo wing (flaps/ailerons) then your flight envelope exceeds just a spoilers installation.

Spoilers are brakes. Flaps are brakes too but can offer more lift (deflected down) or more speed (deflected up). As for braking force flaps offer a massive gain in braking area over spoilers.

Birds use flaps not spoilers...that suggests something :)

Adding flaps can increase the complexity of piloting but they offer massive gains in aerodynamic advantage.

Chris.

[Freakflyin]

If your radio has flaperons and three mixes you can do a basic setup allowing you flaps and flaps coupled to ailerons all switched for landing and flight modes (as long as you can assign switches).

[histarter]

Spoilers increase airspeed when landing, flaps decrease airspeed when landing. My real glider lands like our models... 90 degrees of flap, and no spoilers...

Jack Womack
Ahmen! Very succinct. Spoil a floater; flap a cruiser!

[rdwoebke]

I'd agree it totally depends on the kind of plane.

For example, take the Bubble Dancer. I lhave landed it and its smaller brother, the Allegro Lite it in some crazy tight areas, but they have a spoiler. In thier case, they have a full center section span spoiler and this drops the plane out of the sky quickly and allows me to "parachute" into a landing zone. AKA not going forward very much but dropping quicker.

If you just have a simple 6 channel non computer radio, you might not like either flaps or spoilers. On the planes I have flown, spoiler deployment requires quite a bit of "back stick" and flap requires quite a bit of "forward stick". To make this easier to fly, we have a mix setup that automatically mixes in elevator compensation. In the past, I think mechanical mixing was used for this kind of thing.

Ryan

[davidjensen]

Planes that only have ailerons (no flaps) do not do well with flaps other than DLG's. All the planes I have flown (with out flaps) use spoilers for landing. When the spoilers are deployed the plane is forced down but when you lift the nose to counter the spoilers the whole wing becomes a flap slowing the plane nicely. With that said I have done a few experiments recently with my new X-Pro with flap/spoiler movement of the ailerons. I still need many more hours of experimentation to determine if this works or not but normally I would have the ailerons move up when flaps go down (crow) for landings. I put a condition on a switch that reverses the aileron direction. When the flaps go all the way down (90 degrees) the aileron go about 1/2" down. The ship really gets floaty but stays in control more or less. Does this work better than just crow or no aileron movement? The jury is still out.

[schrederman]

David,

My full-scale glider has ailerons and flaps mixed. They do exactly what you describe. The ailerons follow the flaps from -8 (reflexed) to + 15 degrees. They stay there if I add more flap, all the way to 90 degrees for short landing. I have a new 6-servo model, and it will be set up exactly that way... if my radio will do it...

Jack

[davidjensen]

I do have full TE control for camber and reflex on my left slider and the flaps with crow or additional flaps are on the throttle stick. In cruise mode the flaps are mixed with the ailerons at 40%.

[aeajr]

I have planes with R/E/Spoiler controls. I find them easy to fly and easy to land in a designated area. They work fine with a simple three channel radio. Spoiler to elevator mixing is a nice to have but not necessary for sport flying. Most RES planes can be very effectively flown with manual elevator compensation when deploying spoilers.

You fly the plane into the general area and pop the spoiler. She will come down pretty quickly and smoothly.

For sport flying I don't see a problem with a RES design and it can certainly be flown at lower cost than a full house plane.

Generally I would have no problem landing in a small area. How small? A 50 foot circle would typically be no problem and a 20 foot circle can be easily managed with some experience.


I also have planes that have R/E/A/F. The advantage of this design is is that you can REALLY put on the brakes. For very high precision landing, say in a 6 foot circle, this design has an advantage. However it takes a more complex radio to take full advantage of the wing. It is also more complex to fly as you have more things to control. For contest precision landing this is what you want.

So a full house with an appropriate radio system is a higher cost combo.


For sport flying, either is fine! As long as you have some kind of glide path control you can learn to land either design with precision.

[blueair]

thanks aeajr, makes sense to me, I kind of thought that flaps increased lift and glide slope,where spoilers kill lift causing sink, does this sound close, many thanks

[aeajr]

Blueair, you have it right.

Either system will change the glide slope of the plane, they just do it in different manners. Some planes, like the Spirit 100, have both flaps and spoilers.

Either can be flown on a small field. A very small field would be 200X200, or about an acre. I can land either plane within that field space with no problem.

RES planes tend to be lighter with lighter wing loadings so they can float on lighter lift and can land at very slow speeds. That also means they can be launched with a lighter hi-start, though this is probably not a big deal. With added ballast, light RES planes can be flown in strong wind with no problem.


Full house tend to be heavier with higher wing loadings, though there are light FH and heavy RES planes. As such they tend to land faster, so the slow down of the flaps helps them to land slowly. I am talking about tendancy. FH tend to handle wind better but may not be able to fly in the lightest lift that the light RES planes can soar.

Everything is a compromise. There is no right answer.


Net it out this way:

With full house you have more control surfaces that give you more control, at higher cost, with greater complexity.

With RES you have fewer controls that give you adequate control at lower cost with less complexity.

Either can be flown for sport or competition, and either can win in the hands of a skilled pilot.

Now, you choose which you want. Both are great fun!

[rdwoebke]

thanks aeajr, makes sense to me, I kind of thought that flaps increased lift and glide slope,where spoilers kill lift causing sink, does this sound close, many thanks

You could say that, but that is not completely correct.

On a floaty plane like say an Ava or a Oly, you want it to kill that lift. On a plane like the Ava (or Bubble Dancer) that big old spoiler increases sink rate dramatically while at the same time reducing the glide slope so that the plane seems to slow down from a forward movement perspective.

On a faster/heavier plane (like say a Thermal Dancer, Pike, Supra), the flaps coupled with ailerons have a lot of other advantages. Camber changing, reflex, etc. On the faster plane, deploying flaps like 50 degrees or more increases sink rate (adds a bunch of drag) and slows the thing down. Deploying flaps a little bit also slows the thing down (while adding lift). So flaps can both increase and decrease lift. Deploying the flaps beyond a certian point is not adding any lift at that point, you are just killing it.

[Ollie]

When the flaps are applied and the glider changes pitch to up nose attitude. When the spoilers are applied and the glider changes pitch to down nose attitude.

The Challenger use one servo for both flaps and spoilers. When the flaps are partly down, two strings beween the flaps and start moving spoilers. When the flaps are fully down, the spoilers are fully up. When the flaps are normal, the strings are slack. That way the pitch attitude is not changed when the fully flaps and fully up spoilers. Clever with a simple transmitter but a complex servo linkage. You must fiddle with the servo linkage.

[blueair]

thanks guys, very insightive, Im starting to think that which ever system you use its just a matter of mastering it, either is good, just practice, I know as a pilot I use flaps and make steep approachs, at slow speeds, never had spoilers, many thanks for the very knowledgable input,