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Old Feb 06, 2013, 04:04 PM
Aka: Ralph
Canada, ON, Hamilton
Joined Nov 2012
314 Posts
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Originally Posted by aeajr View Post
The joy of flaps is not to come in fast and HIT THE BRAKES!.

The joy of flaps is to lower the stall speed of the glider by adding camber to the wing. This way you can come up to your landing spot so slowly that you can just kiss the ground gently so as not to wake up the ants.

Crow, is more of a braking tool but it takes away that slow approach as it kills some of the lift of the wings.

That is why I don't use crow or I only use a very small bit of up aileron. My goal is to approach the landing area slowly and gracefully when I am thermal soaring.
Now, on the slope, where the rotor can be severe and you need speed to keep control of the glider, there crow, and its huge braking force can be very valueable. You come up to the landing area with some speed so the rotor does not toss you around, then you high the brakes and drop it on the spot.

The right tool for the right job is what you want.
Newbie question - If both ailerons are slighty up at the same time how does one correct a wing tip or slight roll from a cross wind ??
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Old Feb 06, 2013, 04:25 PM
Proud member of LISF and ESL
LI, New York, USA
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Quote:
Originally Posted by dangerdan View Post
Newbie question - If both ailerons are slighty up at the same time how does one correct a wing tip or slight roll from a cross wind ??
If they are both up then they have equal impact and therefore neutral effect on your flying. You lose lift but you should be flying level.

You still have to correct for cross winds in the usual fashion which might involve both alieron and rudder input. If you can't come directly into the wind then you might want to consider using rudder to "crab" the glider in just like the power guys do.

You will lose some travel on the up aileron so take that into account.
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Old Feb 06, 2013, 04:50 PM
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USA, CA, Chico
Joined Feb 2011
3,249 Posts
I know this is a bit off topic,,, but have you guys seen this BRAND new BIG scale sailplane
HH has just anounced??? Might have to sell my 4.3meter duo discus to get this one
Sure looks PURDY!!!!!:-)
http://www.horizonhobby.com/products...2m-arf-EFL4910

HH!! Your KILLING me!!!! This sure would be a BLAST on the slope. ;-)
Watch the you tube video of it
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Old Feb 06, 2013, 05:44 PM
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Australia, WA, Perth
Joined Feb 2012
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Originally Posted by Piper J3 View Post
A 14x9 CAM might be a little too much prop for a MVVS 4.6/840. You might get better performance with smaller dia / less pitch. Let us know...
The following is taken from the specification sheet that was packaged with the MVVS

"Powered gliders up to 2.5 kgs - 3S, 14x9.5, 27-35 amps average, 45amp maximum for 30 seconds"

I come under ALL of those recommendations so I think it will handle 14x9 just fine...

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Old Feb 06, 2013, 08:40 PM
Aka: Ralph
Canada, ON, Hamilton
Joined Nov 2012
314 Posts
Quote:
Originally Posted by aeajr View Post
If they are both up then they have equal impact and therefore neutral effect on your flying. You lose lift but you should be flying level.

You still have to correct for cross winds in the usual fashion which might involve both alieron and rudder input. If you can't come directly into the wind then you might want to consider using rudder to "crab" the glider in just like the power guys do.

You will lose some travel on the up aileron so take that into account.
I have just gone through this site from top to bottom and book marked all the important details. Its all there, I just have to put it together in my mind.

Thanks
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Old Feb 06, 2013, 08:42 PM
Aka: Ralph
Canada, ON, Hamilton
Joined Nov 2012
314 Posts
Quote:
Originally Posted by Airman74 View Post
I know this is a bit off topic,,, but have you guys seen this BRAND new BIG scale sailplane
HH has just anounced??? Might have to sell my 4.3meter duo discus to get this one
Sure looks PURDY!!!!!:-)
http://www.horizonhobby.com/products...2m-arf-EFL4910

HH!! Your KILLING me!!!! This sure would be a BLAST on the slope. ;-)
Watch the you tube video of it
Thats a nice sailplane, but just a tad to large (LOL)
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Old Feb 06, 2013, 09:23 PM
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USA, CA, Chico
Joined Feb 2011
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Any of you expert sailplane pilots out there have any ideas about a good starting point for aileron to flap mix percentage and aileron to rudder mix percentage???
I have my butterfly/landing mode set so that I have 100% aileron to rudder mix to give me more turning authority with flaps all the way down,, and I also have 0 aileron to flap mix when in landing/ butterfly mode. Any thoughts, suggestions, or comments both negative or positive GREATLY appreciated!!!! :-)
Right now I have greatest amount of aileron to flap mix in speed mode, least amount of aileron to flap mix in thermal mode, and in between mix percentage in normal .
Thanks!!!!! Jerry in Chico
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Last edited by Airman74; Feb 06, 2013 at 09:27 PM. Reason: Addition
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Old Feb 06, 2013, 11:18 PM
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My usual starting point for A to R is about 25%. For some gliders that is enough. For some I have had it as high as 60%. I have it on a switch. When I am in a thermal I turn the mix off and fly the rudder myself.

Flap to elevator - I start around 30%. Test it around 100 feet. Get to a level glider, as if you were making a landing approach. Now ease it in, if you have it on a variable control. Or bring it on with a switch. When it is right the glider should continue to fly with only a momentary disturbance. It should not pitch up and stall, nor should it start to dive.
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Old Feb 06, 2013, 11:45 PM
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Originally Posted by aeajr View Post
My usual starting point for A to R is about 25%. For some gliders that is enough. For some I have had it as high as 60%. I have it on a switch. When I am in a thermal I turn the mix off and fly the rudder myself.

Flap to elevator - I start around 30%. Test it around 100 feet. Get to a level glider, as if you were making a landing approach. Now ease it in, if you have it on a variable control. Or bring it on with a switch. When it is right the glider should continue to fly with only a momentary disturbance. It should not pitch up and stall, nor should it start to dive.
Thanks ALOT AEAJR !!! Funny,, that's exactly about the mixing ratios I have programmed right now. I have set up so I can change mixing ratios on the fly using a aux digital trimmer on my A9
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Old Feb 07, 2013, 11:34 AM
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Now what about aileron to flap mixing?? One thread I was reading suggests starting with about 33% aileron to flap mixing to increase roll authority and reduce drag,, and possibly increasing beyond that in thermal mode to decrease tip stall tendencies.. Any thoughts or opinions on this???
This is why I like full house sailplanes and a sailplane radio,,, you can do soooooo much more,,, and its fun to play around with different mixing ratios in different modes. For instance in both thermal and speed mode I have my right slider able to give me more camber from my starting point or give me more reflex in speed mode. Cool stuff. :-)
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Old Feb 07, 2013, 12:53 PM
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I have down aileron to flap set at about 40% on my Supras, based on my understanding of guidence provided by Dr. Mark Drela, MIT, who designed the Supra and the airfoils in use on the Supra. I use about 50% on my Graphite 3.4M glider which has a different airfoil.

My flaps don't allow much up so mostly they follow the down aileron, not the up. The goal is that you will need less down aileron, less stick movement, which means less drag and less adverse yaw on the down aileron side. The flap goes down 40 to 50% of the down aileron throw.

There is a lot of aerodynamic testing and theroy that lead to that recommendation. Mark's comments suggest that the amount shoud be based on the relative size distribution between the flaps and the ailerons. I am using 40 to 50% and it seems to work well.

You can read Dr. Drela's comments here:
http://www.rcgroups.com/forums/showt...21#post1372711

If you want to test it, put the mix on a switch. Turn it off and fly the glider for a while. Then turn it on and fly the glider. See which you like better.

I am not looking for faster response or better aerobatic rolls. I am looking at getting the roll I am looking for with the minimum surface deflection. The more we deflect the surface the more drag we produce which means faster sink.

Smaller aileron deflections may also mean less adverse yaw so it may mean a lower aileron to rudder % which means less drag.

It is all about reducing drag!


If you want to read more on things like aileron differential and such, take a look at these threads. 100s of posts on this and related subjects by some pretty knowledgable guys. I don't pretend to understand it all but I have read it all. Guranteed to make your head hurt.


Aileron to Flap Ratios – Aileron Differential
http://www.rcgroups.com/forums/showt...t=aileron+flap
http://www.rcgroups.com/forums/showt...t=aileron+flap
http://www.rcgroups.com/forums/showp...26&postcount=4

Aileron Differential – yes or no?
http://www.rcgroups.com/forums/showthread.php?t=1481705

aileron to flap mixing – benefits – note post by Dr. Mark Drela
http://www.rcgroups.com/forums/showthread.php?t=158021
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Last edited by aeajr; Feb 07, 2013 at 01:26 PM.
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Old Feb 07, 2013, 01:46 PM
Registered User
USA, CA, Chico
Joined Feb 2011
3,249 Posts
Wow!!! Thanks just what I'm looking for!! Ill read it ALL.
Interestingly I sorta intuitively set my A-F mix at 40% just by the way it looked
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Old Feb 07, 2013, 02:54 PM
Aka: Ralph
Canada, ON, Hamilton
Joined Nov 2012
314 Posts
DX8 question

For those using the DX8 what is the "Wing type". I have selected 2 Ail and 2 Flaps.
Is this option correct or do I select something different.
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Old Feb 07, 2013, 05:38 PM
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Originally Posted by dangerdan View Post
For those using the DX8 what is the "Wing type". I have selected 2 Ail and 2 Flaps.
Is this option correct or do I select something different.
Depends how many channels your receiver is,, if you want all 4 servos in wing on their own separate channel , then yes you'd select 2 flap, two ailerons, but you'll need an 8ch receiver for that set up with DX8, if your willing to Y harness the two flaps together, then select 1flap and 2 ailerons and use a 7ch receiver. Spektrum doesn't allow custom assignment of channels on DX8, so if you chose 2 flaps that means 1ch for each flap even if you have 2 servos but are y harnessing them then that would considered 1 flap cause only one channel is driving both flaps, or you could y harness both ailerons into one channel and have each flap on their own channel. The wing type determines how many channels it will transmit to.. Does this make sense?? Or am I confusing you??
Basically the first five channels with DX are ALWAYS the typical Rudder, elevator,ailerons, throttle and gear PLUS anything beyond that like 2aileron channels each aileron on its own channel and no flaps would be 6ch, 2 ailerons and one flap channel ( flaps y harnessed ) 7ch, 2 ailerons and 2 flaps would be 8ch,, so you'd need corresponding number of receiver channels to accommodate each of those set ups. Hope this helps. :-)
There's many different ways to set up a sailplane with DX8 to get close to full sailplane functionality
For instance you can put throttle on Gear, flaps y harnessed together on throttle and separate aileron channels for flaparons, With this set up you'd only need a 6ch receiver,, many different ways to configure. I believe HH has some templates that are used on the radian pro that would work. Check their web site. I've found for maximum sailplane functionality with DX 8 you'll need a 8ch receiver in order to put each servo in the wing on its own channel. Maybe AEAJR has some ideas
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Last edited by Airman74; Feb 07, 2013 at 05:55 PM. Reason: Correction
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Old Feb 07, 2013, 05:44 PM
Electric Glider Nut
timography's Avatar
Australia, WA, Perth
Joined Feb 2012
357 Posts
Quote:
Originally Posted by dangerdan View Post
For those using the DX8 what is the "Wing type". I have selected 2 Ail and 2 Flaps.
Is this option correct or do I select something different.
if you want camber and reflex as well as crow and normal flaps, you might have to select "Flaperon" as the DX8 [or the DX7s] does not have specific sailplane programming features; so you have to get creative with your mixing...

I'm by no means an authority on the matter though, head over to the DX7s/DX8 programming thread. [Freechip] is the admin over there and theres not a lot he doesn't know when it comes to the DX8...

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