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Adding spoilers to Bird of Time ARF

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Adding spoilers to Bird of Time ARF

Old 06-08-2020, 08:17 PM
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Stubby01
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Default Adding spoilers to Bird of Time ARF

I purchased a Dynaflite Bird of Time ARF kit a couple of weeks ago, from a local hobby shop, they had 2 on the shelf, and thinking of getting the 2nd one since they are not made anymore.
Due to the area I fly in, one way in, one way out, sloping runway with a chicken coop as a back stop, not good. I hear the BOT loves to glide and hard to spot land. Would anyone have plans, diagrams, or info of adding spoilers? It will be hard to do since the center section of the wind is one piece now.
Old 06-10-2020, 03:09 PM
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speedracerntrixie
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To be honest, I think you would benifit more from the addition of flaps. Spoilers will kill lift which is very helpful to get out of powerful thermals but they don't do much in the way of slowing down the sailplane. Adding flaps would allow for slower landings, can be mixed with rudder to act somewhat as ailerons and can be used for better launch height if using a high start or winch. They could also be deployed a small amount to aid in circling in small thermals where the added lift and slower flight speed would be useful.
Old 06-10-2020, 04:51 PM
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Stubby01
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Default Adding spoilers to Bird of Time ARF

Would there be drawings, instructions or plans showing on how to add spoilers to an already built wing (ARF)? The center section is one piece.
I hate to cut open a brand new wing without first knowing on what the heck I am doing.



Originally Posted by speedracerntrixie View Post
To be honest, I think you would benifit more from the addition of flaps. Spoilers will kill lift which is very helpful to get out of powerful thermals but they don't do much in the way of slowing down the sailplane. Adding flaps would allow for slower landings, can be mixed with rudder to act somewhat as ailerons and can be used for better launch height if using a high start or winch. They could also be deployed a small amount to aid in circling in small thermals where the added lift and slower flight speed would be useful.
Old 06-10-2020, 05:00 PM
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speedracerntrixie
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Not that I am aware of. The BOT has a fairly common wing construction. I would suggest looking at a few old school sailplane plans on outerzone that incorporate spoilers. Once you see how they are built into a wing I think you will think it quite easy.
Old 06-11-2020, 04:44 AM
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Fidd88
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I think from a structural point of view, you might be better off adding an external spoiler arrangement to the fuselage. Like the speed-brakes (I think they were) on the fuselage of an F86. This could give you buckets of variable drag to use on approach, with tension loads to the fuselage structure which should not be a problem, but wouldn't involve cutting into wings of the fuselage, beyond the holes required for leads or actuating arms. I'm not familiar with the model so can't offer further on the fitting side of things. If I were retrofitting a glider, this is how I'd go about it. I think retrofitting spoilers/flaps/air-brakes to a wing not designed for them is very dicey, with all sorts of loads being applied to the wing-roots, possible tortional loads and all manner of nasties. So an external deployable speed-brake added to the fuselage in such a way as it produces little or no additional frontal area or surface-drag might be the way to go?

if you do go the route of the F86 style speed-brakes on the fuselage, you'll need to be careful that turbulent air aft of the spoiler doesn't affect air-flow over the elevator.
Old 06-16-2020, 01:12 AM
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I would add a double panel of balsa, let into the ribs just behind the spar, 10" long by 2" wide. Cut a slot 8" long x 1" wide for the blade and let this into the ribs so that the profile is maintained. this should ideally be outboard of the tailplane. The bottom sheet can be 1/16th", but the top sheet should be 1/8". The blade should be made from 1/16" carbon sheet faced with 1/16" balsa, hinged at the front by small flat kavan style hinges.. Now you need to actuate the spoilers. Two ways: 1. Put a small servo under each blade to actuate them. The downside is that you need to make a hatch underneath to get to the servo for set up and matenance. 2. use a length of plastic covered steel fishing trace to pull each spoiler up and a very light return spring. Run the fishing trace through some snake tube curved around in a long curve and exiting the underside of the wing root facing forwards. Move your rudder servo to the space under the wing and have a spoiler servo in its place. Make loops in the end of each length of fishing trace about 1/2" long or a little less. Screw a small cheese head screw into your servo arm and pop the loop onto it. You need to get the length just right so do all this prior to covering. The spoilers need to move together and close completely flat. Cover the spoiler and fix in place prior to covering the wing to ensure its still works when covered.
This model does not need flaps or airbrakes. It already flies slowly and has oodles of wing area. Its not an F86 and airbrakes are not needed, and indeed they work on the principle of the drag increasing at the square of the speed. It does not have much speed to begin with. Spoilers work proportionally and are ideal on slow models. Mine had been flying 40 years. Its does not have spoilers so I use the rudder.
John
Old 06-19-2020, 08:56 PM
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Here is my tutorial for installing electric spoilers in a Dynaflite BOT ARF:

https://www.rcgroups.com/forums/show...g#post22872045

Old 09-08-2020, 03:16 AM
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A470Soaring
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A friend of mine has added a very simple spoiler arrangement to his BoT where the spoiler is hinged using iron on film and then a long arm on the servo pushing the spoiler up. Two small magnets hold the spoiler in position. I have a video, hopefully being published on YouTube this Friday, which shows the arrangement and I'm considering adding this arrangement to my own BoT.

It isn't a case for me of slowing down the model but killing the lift and getting the thing onto the deck as ground effect seems to keep the thing in the air forever and it can be so easy to over shoot the LZ.

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