RC Gliders, Sailplanes and Slope Soaring Discuss rc gliders,rc sailplanes and slope soaring in this forum. Thermaling techniques, airfoils, tips, etc

Spoilers vs flaps

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Old 07-28-2016, 09:49 PM
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wagspe208
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Default Spoilers vs flaps

I understand the difference in location/ design...
I was wondering if... for landing... which is the "best" as in slowing down the plane. Or is it hugely model design specific..
Or put another way... if a guy is searching for a model.... are spoilers better in function... I also understand they add weight.
OR would flaps w/ ailerons be best... again, weight..
OR, ailerons mixed to function as flaps...
I bet this is so hugely subjective it is a total waste of time... but this forum isn't posting 50 threads a day.
Thanks
Wags

Oh, I was looking at the Allusive, then saw some esprit models that look great, and of course soaring usa.
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Old 07-28-2016, 10:51 PM
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Aquila1954
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Well, I have never used flaps before. I mostly fly RES. Spoilers to me help out in 2 areas. One for more of a precision landing, and to get me out of a Boomer of a thermal.
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Old 07-29-2016, 01:14 PM
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Totally agree Aquila , spoilers have saved the bacon more than once .
The only ship I own without them is a Quasoar (123") that just has flaps . When it get stuck in lift , it can be a nightmare to get it back .
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Old 07-30-2016, 07:56 AM
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da Rock
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Flaps have one feature that spoilers can't match and is a plus to many. They can be reflexed to get better distance coverage. It isn't something beginning glider guiders are going to find easy to trim.

Flaps have one characteristic that spoilers don't and it can cost money and time. Very often, if not retracted just before touch down, they can hit the ground and trash the servo gears.
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Old 07-30-2016, 08:12 AM
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da Rock
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I've had a couple of flap equipped sailplanes. I really can't say the reflex was better than a simple wing with a good L/D airfoil. And I've had more than one servo trashed. Even on a wing it looked like it shouldn't have.

I've had and have a number of spoiler equipped sailplanes. My experience is spoilers are the best and safest help getting down out of heavy lift. They are good help getting close to the pin on landings. If I had to choose, the choice would be spoilers.
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Old 07-30-2016, 08:39 AM
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wagspe208
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That makes sense. I did not think about flaps being able to hit the ground. I have had flaps on profile planes, but the ground was not an issue with landing gear.
Thanks
Wags
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Old 07-30-2016, 04:52 PM
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Jennifer Curtis
 
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Another thing about flaps is that when the
glider is going really slow with the flaps
down, (like when landing) if you raise the
flaps, the planes loses that extra lift, and
may stall. This is not a problem when the
plane is 6-12 inches of the ground, but can
be a real problem at 5 or 10 feet above
the ground.

When spoilers are retracted, there is an
increase in lift, so no stall will occur.

Jenny
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Old 07-30-2016, 06:16 PM
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Agreed , things can get stupid real fast at 5-10' agl.
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Old 08-01-2016, 10:38 AM
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I would go for the flaps any time, then you also can have all span ailerons/snapflaps/Crow brake.
And with flaps you can dive vertical forever without overspeeding, and even land in the lift area at the slope.

https://www.youtube.com/watch?v=v0H6hDvC5x8 https://www.youtube.com/watch?v=p6RHAx100sk&index=4&list=PLWto3tazMLB_kuhZbzKFNtWuGN5TCdztH https://www.youtube.com/watch?v=O6fHlh255VQ Cheers
Soren
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Old 08-02-2016, 06:14 AM
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Interesting you mention the Allusive, which has neither flaps or spoilers
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Old 08-02-2016, 11:47 AM
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wagspe208
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Originally Posted by BarracudaHockey View Post
Interesting you mention the Allusive, which has neither flaps or spoilers
Ah, lack of completing a thought. The allusive was such a cool looking piece.. it was the reason I started looking at ep gliders to begin with... Then as I did more research, I saw many have spoilers/ flaps... then which is better and why...
Sorry for the confusion.
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Old 08-02-2016, 07:01 PM
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Personally I would not want a sailplane without flaps. The thought about retracting the flaps in flight and stalling is pretty much a myth. On all my sailplanes the flaps are on the throttle stick and are used to control speed and glide path while on approach. With the correct mixing you can camber the entire wing in light lift or reflex the wing to speed out of sink. Launches are much higher with a camber setting as well
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Old 08-03-2016, 10:24 AM
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Flaps are "the better option" for permitting an aircraft to fly more slowly.

Spoilers "require" a speed increase. Think about it.

You can retract flaps and stall ... it is called a "change of configuration stall". A competent flyer will not encounter any such problems, though.
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Old 08-03-2016, 11:29 AM
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wagspe208 in his opening post gave the best answer. The choice between spoilers and alternative devices depends on the pilot’s objectives and the plane’s design. The worst option is to have no way of killing lift and shortening the landing. I have one such electric glider. It is a fabulous flier but one day it took nearly thirty minutes to get out of lift. Spot landings are out of the question.
 
My experience is that spoilers are not as effective in slowing a plane as a combination of flaps and ailerons used as spoilerons. Yet spoilers are adequate for the purpose. The installation is lighter. Cramming a full-house installation into a two-meter sailplane can get overly heavy.
 
Allan
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Old 08-16-2016, 06:59 PM
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It really depends on the application. As in slope or thermal. Spoilers stop the laminar flow over the wing reducing lift. Flaps can increase the lift for sustaining flight and a slower air speed. If you fly slope. Use spoilers. If you fly over a field as in aero tow or winch use flaps. If you want the best of both worlds use both. When I flew sailplanes in competition I used spoilers to make those spot landings. Hope this helps.
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Old 09-02-2016, 08:56 AM
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I have gliders equipped with flaps and spoilers, with flaps you get the advantage of being able to alter the wing camber for lift and speed and in conjunction with raising the ailerons ability to have crow/butterfly for extra drag for landing, but your radio needs to support this option. For landing spoilers and crow/butterfly braking both work equally well, raising the ailerons as spoilerons to kill lift also works but not as well. And when using butterfly where the flaps will be lowered 60 degrees or more, raising them doesn't increase the stalling speed. If the glider isn't equipped with flaps then I'll fit airbrakes/spoilers, if it has flaps then I'll set them up to be able to use crow braking and not bother with spoilers.
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Old 10-02-2016, 06:08 PM
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Speed,
"On all my sailplanes the flaps are on the throttle stick and are used to control speed and glide path while on approach. With the correct mixing you can camber the entire wing in light lift or reflex the wing to speed out of sink. Launches are much higher with a camber setting as well"

On another site I have been asking a question about a polyhedral wing plane but with full span flaps. Wondering if there would be any advantage in being able to reflex or camber the entire wing as needed. Speed from your answer here it sounds like it might be an idea to explore. Yours or any ones thoughts.

Last edited by gratter; 10-02-2016 at 06:14 PM.
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Old 10-03-2016, 09:20 AM
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Playing with the Arthobby Odyssey with flaps/crow in the lift zone:
https://www.youtube.com/watch?v=hDN5p29PzTY

Cheers
Soren
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Old 10-03-2016, 09:50 AM
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Very cool video!
I know with straight wing planes there is a advantage. My thoughts are about Polyhedral, thermal duration planes and if having the ability to adjust camber over the whole wing gives you any advantage.
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Old 10-03-2016, 08:40 PM
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Polyhedral is provided to give stability and helps rudder only turns, the wing section used will determine if using camber flaps helps. A lightweight thermal soarer normally has a wing section optimised for floating around so I'm not sure if camber flaps would assist in this case.
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