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Old Jun 19, 2012, 10:45 AM
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markminc's Avatar
United States, NC, Hampstead
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Flaps/Spoilers

My first post, although I have learned a bit over time reading posts.

I have a new racer, EFlite Shoestring, cool plane but much faster than anything I've flown before and it seems to glide forever. We have a smaller field and landing approaches are difficult with this planes ability to glide.

I wonder if I can program an offset triggered by an unused switch to provide an offset to my ailerons so they act as flaps. I would still like to use my ailerons as ailerons at the same time. So, I want to place a down offset on each aileron when the selected switch is set.
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Old Jun 19, 2012, 11:09 AM
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whitecrest's Avatar
Orleans, MA
Joined Feb 2007
2,104 Posts
Welcome to the forum.

You are probably looking for a flaperon mix. Evidently, there are lots of options:

http://www.airfieldmodels.com/inform...l_aircraft.htm
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Old Jun 19, 2012, 12:03 PM
jrb
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Edina, MN, USA
Joined Oct 1999
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YMMV but I wouldn't do flaps!

Spoilers, Yes; do it all the time -- like w/SunDowner 50:

Strip or outboard Ailerons will increase the "tip" stall potential.

Spoilers will add some sink rate and allow you to slow down a bit more using pitch/elevator.

BOL!

Jim
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Old Jun 19, 2012, 02:01 PM
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Since the ailerons on the Shoestring are small and at the outside of the wing, they will not be effective as flaps - they will cause a tip stall. You need to learn to do a proper approach with the Shoestring, and you should be holding more and more elevator all the way down. It is a hard to land airplane, and there isn't a whole lot you can do about that except improve your technique. You are not allowed to add "proper" flaps if you want to race in EF-1, so there isn't much you can do.

Look at the placement of the ailerons - they are too far out to serve as flaps. Warning: this plane has a NASTY stall behavior - it's better to come in fast.

electric formula one racer by jasmine25011, on Flickr
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Old Jun 19, 2012, 05:18 PM
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Welcome Markminc!

You'll find all views on the forum - so here's a different one!..
I use flaps on all my models (mainly because they are scale and the full size aircraft has flaps) and find that they allow my models to slow down considerably for landing.
As has been said, to use ailerons to act as flaps, in other words to have a downward deflection as a flap would would be potentially disastrous because of the increased likelihood of tip stalling.
The reason that flaps are always sited on the inboard part of the wing is that when down they effectively increase the incidence of the inboard section of wing so that more of the load is taken by that part of the wing, reducing the load on the outboard section. This allows the ailerons to continue to work and has in effect given the wing a large dose of washout, so reducing the risk of tip stalling.

A lot of the gliding fraternity use 'crow' braking, which applies an equal amount of up to the ailerons thus doing the same job but effectively reducing the incidence of the section of the wing having the ailerons. This would give you a much better and safer result but you will find the nose drop on switching the up-aileron in, so you will need to be ready with the elevator or program some elevator in with crow.
Crow will not slow your model down as much as flaps would because it does not add lift but spills it, but it will allow you to drop into the landing strip much quicker.

If you are happy to make alterations to the model the ailerons could be split so that the inboard section can become flaps proper. This will slow your model down as well as adding lift and is to my mind a much better solution. You can choose how much drag and lift you add by choosing the right angle of deflection for your flaps.
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Old Jun 19, 2012, 06:56 PM
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Thanks

Thank you all for your responses. I believe before I try a modification to my flaps I will try and program in "crow" braking as suggested with some mixed elevator support. Yes, more practice and things should improve.
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Old Jun 19, 2012, 08:29 PM
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Quote:
Originally Posted by markminc View Post
Thank you all for your responses. I believe before I try a modification to my flaps I will try and program in "crow" braking as suggested with some mixed elevator support. Yes, more practice and things should improve.
You can't do crow because you only have one surface to work with. IMO, a good mod would be to put actual flaps on the inside of the wing - then you could do crow, which is "flaps down, ailerons up" You could also do spoilers which is "ailerons UP"

Having flown the Shoestring quite a bit myself though, I think either thing is pretty likely to just mess it up rather than produce any reasonable slowing action. It doesn't have a lot of throw on the ailerons, so if you put them up (or down) you are going to lose some maneuverability, and you know it doesn't roll too fast anyway, much less at slow speed.

Mixing is allowed, but adding flaps or splitting the ailerons would probably not be allowed for EF-1. Are you running the racing or sport setup?
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Old Jun 20, 2012, 12:04 PM
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I am doing a bit more in depth reading about crowing, never heard that before this q and a. I have only flown my Shoestring about 6 times and still feel it is a handfull getting it down in one piece. Only day it was easy we had about 10 knots of wind to land in.

No, I do not plan to race or compete with the Shoestring, just having fun. I have experimented with different props. and batteries. Have a Power 25 which turns relatively slow and a 10x10 prop, a 8x8 prop, and a 10x5 prop. I have both 3 cell and 4 cell battery and have tried all combinations. Plane is like a rocket with the 10x10 prop and a 4 cell. Am now flying with a 10x5 prop and a 4 cell and it is very fast. (Clocked on radar at 81 straight and level with the fast set up)
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Old Jun 20, 2012, 01:42 PM
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Be careful about the power usage with those setups. From what I understand, it's supposed to be around max power with the 8x8 on 4 cells
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Old Jun 20, 2012, 01:51 PM
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United States, NC, Hampstead
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yes, I have checked all of the configurations on a watt meter and I am OK. Not using the motor or ESC spec'd by Eflite, The motor I am using is the same physical size as the racing motor spec'd but has the slower kV or speed of the sport motor. My motor and ESC are rated at max 58 and 60 amps and the highest current I have seen in any configuration is 51. Max watts shown also tracks with the current and is below the motor rating.
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Old Jun 20, 2012, 01:53 PM
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Cool, I'm running the racing setup. I enjoy racing and I like to win
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