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Old Mar 25, 2007, 02:47 PM
rodw is offline
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Question

bird of time spoilers


I am just about to start building a bird of time kit and would like to know the practicalities of building in spoilers, does anybody have any info on this
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Old Mar 25, 2007, 06:16 PM
ShaverR6 is offline
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I am just finishing the Kevlar spar wrapping on my BOT wings and i have been thinking about spoilers. I am definitely going to install some, but i am not sure which type. From what i have read spoilers are almost a necessity when landing, the bird just wants to glide and glide. Spoilers would add more control during landing and reduce the chances of an overshoot. The majority of People here install hinge type spoilers, but I have been thinking of building my own Graupner scissor type spoilers. I may just bite the bullet and buy a set of the Graupners. I would appreciate to hear what others have to say on the subject as well.
Old Mar 25, 2007, 09:48 PM
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Spoilers are pretty much a necessity. They don't have to be large or complicated. Have a look through the Yardbird thread at the spoiler section. The same setup would work nicely for your BoT.

Jack
Old Mar 28, 2007, 08:18 PM
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Sorry for the contrary post, but if you are not contesting (an some say even if you are) spoilers are not necessary. You can always get a plane down by moving the stick to the coroner or diving the plane down to a lower level. If you work with your plane and spend time learning control and energy management you should be able to spot land your plane. This takes time and skill to learn but you can spot land a plane without spoilers or flaps. I you are a sports flyer and want to learn to control you plane, build it without the spoilers (or build it with but cover them). If you want to get into the contest seen, and need help with spot landings, then go for the spoilers. I just recovered a wing this winter and I covered over the spoilers. I do not compete and want to learn more about flying and managing the plane.

Just my 2 cents

John
Old Mar 28, 2007, 08:53 PM
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Spoiler are nice, but not absolutely needed


Quote:
Originally Posted by rodw
I am just about to start building a bird of time kit and would like to know the practicalities of building in spoilers, does anybody have any info on this
Would I build w/o them.......NO.

Last week I went flying with my BoT in about 12mph wind. Didn't use them for one single landing. Still doesn't mean I'd want one w/o them. Yes, you can put the control stick in one of the lower corner and spiral down, but you can come down even quicker if the spoilers are up. You'll find that with enough "up" trim with the spoilers deployed you can come down out of 90% of the thermals with just the spoilers. Personally, if flying w/o spoilers I'd just fly the plane inverted and you will come out of the sky quite quickly.

They can be quite simple, just a piece of 1" trailing edge just aft of the spar. If you need details let me known and I'll measure the length and placement. My wing is in my car as I type this to you. I have my servo mounted in the center section(3 pcs wing) and use pull strings to each spoiler. If I had to do it again(this wing is over 3 years old) I'd place a small cheap servo in each wing and connect the servo directly to the spoiler.

Stan
Old Mar 28, 2007, 09:34 PM
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If you do decide to add spoilers please note that the TE of the spoilers must be 2 inches forward of the wing TE to be RES legal (if you intend to contest in RES classes). Any disruption to the airflow over the wing will affect lift. No matter how good of a builder you are you will disrupt the airflow and cause a loss of thermal performance with spoilers, even when they are closed. One thing for sure is the farther back you can places the spoilers in the wing the better for the wing will perform in lift.

John
Old Mar 28, 2007, 11:16 PM
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Need Spoileers


Flew the original woody BOT for years and won many contests with it.

I used the original design spoilers in the position behind the spar, it is the most effective position, and don't worry about the position being detrimental to the thermal performance of your ship, mine thermalled like a dream WITH the standard spoilers.

ShavR is right that the BOT when she gets down into the ground effect just goes and goes and goes it just never seems to want to settle in that last 300mm [last foot for the non-metric]. Great for your duration time but lousy for nailing the spot.

If you are going to fly in any form of contest you will need glide slope control and that is what spoilers are useful for, especially for killing lift/ground effect in that last foot to nail the spot. My best spot landing ship ever.

One comment on the size of the spoilers though, was that the original size will require something more than balsa to prevent the blades warping in the hot sun. I finished up using 3mm lite ply sanded to match the wing shape.

Cheers
GG
Old Mar 28, 2007, 11:20 PM
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John, think your wrong about position of spoilers for RES


Quote:
Originally Posted by jrgospod
If you do decide to add spoilers please note that the TE of the spoilers must be 2 inches forward of the wing TE to be RES legal (if you intend to contest in RES classes). Any disruption to the airflow over the wing will affect lift. No matter how good of a builder you are you will disrupt the airflow and cause a loss of thermal performance with spoilers, even when they are closed. One thing for sure is the farther back you can places the spoilers in the wing the better for the wing will perform in lift.

John
I know that the "Big Birdy" series of BoT's place the spoilers closer to the trailing edge, but I don't believe that is mandated in RES rules. All the old timers placed the spoilers just aft of the spar.

Stan
Old Mar 28, 2007, 11:30 PM
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Quote:
Originally Posted by Stan_in_AR
I know that the "Big Birdy" series of BoT's place the spoilers closer to the trailing edge, but I don't believe that is mandated in RES rules. All the old timers placed the spoilers just aft of the spar.

Stan
To be clearer I guess I should have said ďat leastĒ 2 inches in front of the TE. They canít be closer to the TE than 2 inches. You could put them on the LE if you want, but the longer you leave the airflow over the wing undisturbed the better the lift.

John
Old Mar 29, 2007, 02:24 AM
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Can anyone send me details for spoilers for BOT
Old Mar 29, 2007, 08:24 AM
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Quote:
Originally Posted by basils
Can anyone send me details for spoilers for BOT

This is not on a Bird of time, but it is a great way to connect the servo to the spoiler. No slop and no string or added wire etc.

John


P.S. if you glue or tape down the servo put a length of Kevlar string under it so that the ends stick out a few inches. You can be used the string to cut the glue or tape by working it back and forth to get the servo out later if you need to.
Old Mar 29, 2007, 10:11 AM
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Quote:
Originally Posted by jrgospod
This is not on a Bird of time, but it is a great way to connect the servo to the spoiler. No slop and no string or added wire etc.

John


P.S. if you glue or tape down the servo put a length of Kevlar string under it so that the ends stick out a few inches. You can be used the string to cut the glue or tape by working it back and forth to get the servo out later if you need to.
John,

I really like your setup. My BOT spoiler control is similar, but I elected to use a rubber band to pull it (them) down with the servo arm pushing it up - no slotted linkage as you have. I intend to modify it to be more like yours... thanks for the photo.

...bob
Old Mar 29, 2007, 11:11 AM
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Here is a link about adding spoilers to a Dynaflite BOT ARF:

http://dozone.com/SBOT.htm

and a general link to a lot of BOT's with various mods including spoilers and flaps:

http://isoar.ca/~andrewm/rc/bot/

Hope these help.

Randy . . . . . .
Old Mar 29, 2007, 11:27 AM
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Quote:
Originally Posted by bobthenuke
John,

I really like your setup.
...bob

I canít take credit for that. I found it on the web and just saved the picture for reference. It is a great positive linkage. No need for weights, springs or magnets.

John
Old Oct 02, 2007, 12:06 PM
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I like the KISS method. Spoiler blade taped to the wing, rare earth magnet on the blade and a bend paperclip inside the wing. A servo with a long arm pushes the spoiler up.


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