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Old Jan 30, 2013, 04:39 PM
Little_Eddie is offline
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SKSS Delaware AMA 1010092

Long Reach & Pick Up


So I was in Dollar Tree today picking up some more foam and looking around and I think I found a keeper.

Tool Bench Hardware, Long Reach & Pick Up tool.

It's a 31.5 inch steel tube (1/2 (12mm) dia) weighting in at 46 grams, 3 grams more then the 27.5 inch FB wing support for my Radian Pro.

As a bonus when I took it apart there's a nice 35 inch cable all set up for a push-pull setup. A round eye on one end.

Just something to look at
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Old Jan 30, 2013, 10:13 PM
Ricklandia is offline
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Quote:
Originally Posted by Backwall View Post
Until I get a picture, I hope this will help. Place your servo over the wing and aileron with the center of the servo horn on the hinge line...

Dave
Dave, thanks for sharing this, great idea!
Old Jan 31, 2013, 04:02 AM
Old_Robin is offline
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Old_Robin
I have built my first model (Snoopy) with Elevons and I have a Spektrum DX6i. I thought that my experience might be of use as I found the Spektrum manual as much use as a chocolate fireguard.
Elevons, for noobies, are two control surfaces at the back of the wing of a delta or flying-wing that serve as both elevators, by going up and down in concert, and as ailerons by one going up when the other goes down.
In the Set-up menu of the DX6i and other programmable transmitters (not simple ones like the DX4) there is an option of Wing Type. The options are for Dual Ailerons, Vee–tail, and Elevons.
If you complete the model and connect up the two servos, one plugged into the “aileron” and the other to the “elevator” output channel of the receiver, and do no programming at all then one of the control surfaces will wiggle up and down on the elevator stick movement and the other will wiggle when you use the aileron stick.
Go to the Elevons menu and make it “active” and both control surfaces wiggle when the Elevator or Aileron stick movement is used.
The ideal is that the control surfaces move together under Elevator, and that “pull back” moves them up. The aileron control should move the surfaces in opposite directions and the left surface should move up when the stick is moved to the left. You have a snow-ball’s chance in Hell of this occurring at first set-up, and this is where I had the trouble.
I found, by hair-tearing-out experience, that the best way to set up the Elevons was look at Elevator first. If these are not operating correctly go into the “Reverse” section and reverse the sense of one or both servos until the elevator movement is correct.
You are now way beyond the “Help” of the manual! You can RTFM as much as you like without success. I know.
Are the ailerons correct? Does left-stick raise the left control surface and lower the right surface. If so, you are allowed a conceited grin. If they are reversed THERE IS NOTHING YOU CAN DO WITH TRANSMITTER PROGRAMMING TO CORRECT THIS so do not spend a week (oops!) trying to work out how to do it.
If the ailerons are wrong it is logical that the “left” aileron and control surface has been put on the right side and the “right-side” aileron and control surface has been put on the left. By far the easiest way of correcting this is not to rebuild the model, but to swap the plugs over from the Aileron channel and the Elevator channel at the receiver output. This will have no influence on the proper operation of the Elevator, as they were both going in the same direction. However this will correct the Ailerons, which CANNOT BE DONE WITH PROGRAMMING, at least not simply on the DX6i as far as I can see.
One other point to mention, Elevons drive the servos with two stick channels simultaneously, so if you apply some elevator while on full aileron, you will exceed 100% travel. The actual travel comes from Pythagoras as they are at right-angles to each other so two inputs of 100% actually creates 141% of travel. This is considered socially unacceptable to servos which really do not like going above 125% of the “design” travel.
To be kind to the servos the rates on both channels should be limited to 80%, which squaring, adding and square-rooting gives 110% of travel maximum. If you would prefer to limit the throw to 70% on the two channels, this will be 98% of full throw on the servo at its maximum.
Sorry this is a long post, but I had some trouble finding the information and I hoped this might help another Noobie sometime. Happy Flying
Old Jan 31, 2013, 06:01 AM
jetcommander is offline
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Wow that´s a book! Your question: "Does left-stick raise the left control surface and lower the right surface" yes it must!!! a raised airleron pushes the wing down and a down aileron pushes the wing up! So.... if you are standing behind your aircraft and you go right stick (i.e to turn right) then the right aileron must rise so that the wing will go down in flight and the left must go up and have a down aileron.
Last edited by jetcommander; Jan 31, 2013 at 06:07 AM.
Old Jan 31, 2013, 06:04 AM
Old_Robin is offline
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Yes. Good point, but I reckon that forward on the aeroplane is forward. To the left is then off to the left from behind, so you should be behind the airplane (you in the US?) looking forwards. Help?
Old Jan 31, 2013, 06:08 AM
jetcommander is offline
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Originally Posted by Old_Robin View Post
Yes. Good point, but I reckon that forward on the aeroplane is forward. To the left is then off to the left from behind, so you should be behind the airplane (you in the US?) looking forwards. Help?
If you mean me, no look beneath my name I´m in Germany.
Old Jan 31, 2013, 06:13 AM
bhcnomo is offline
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James Stockton
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here is my Synapse build
the wing is done
got to build the Fuselage
Old Jan 31, 2013, 08:31 AM
Old_Robin is offline
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Old_Robin
Thanks Jetcommander. I noticed after I posted and editted my profile to add my location too.
Old_Robin
Old Jan 31, 2013, 01:05 PM
syzygyQ is offline
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Quote:
Originally Posted by Backwall View Post
Here are a couple of my latest builds. It slings a lot of weight under the wing so it's quite stable. Or in other words, it doesn't roll worth S#$t!. On it's first flight a control horn also pulled loose on the aileron, but I was able to land it okay. All control horns now have back plates! .
Nice. I notice in your recent builds that the stabilizer to wing surface area ratio seems to be low. Would you please elaborate a bit on your design / decision making process on this ratio?

Nice to know about that aileron popping issue. I've been pondering whether or not to put base plate horns on my Axon wing -- the thinking being that as the rudder has a horn baseplate, in the event of losing a wing aileron the rudder could still be used for control and navigation. There's minor engineering and aesthetic issues involved -- any secure linkage in the control surface chain, though, must be better looking than a suspect link.

Also nice to learn about the stability / roll characteristics of weight below the wing. Suppose you have to mount a large mass right at the fore-to-aft CG, and have a choice of where to mount it from top to bottom? Where would be better if you want to maximize stability, and have no interest in rolling? As low as is feasible? A bit below the top-to-bottom CG? Above the CG (doubt it -- what happens though to stability when you lift the top-to-bottom CG)?

Thanks!
Last edited by syzygyQ; Jan 31, 2013 at 02:56 PM.
Old Jan 31, 2013, 03:54 PM
Backwall is offline
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Racquetball Lives!
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Quote:
Originally Posted by syzygyQ View Post
Nice. I notice in your recent builds that the stabilizer to wing surface area ratio seems to be low. Would you please elaborate a bit on your design / decision making process on this ratio?

Nice to know about that aileron popping issue. I've been pondering whether or not to put base plate horns on my Axon wing -- the thinking being that as the rudder has a horn baseplate, in the event of losing a wing aileron the rudder could still be used for control and navigation. There's minor engineering and aesthetic issues involved -- any secure linkage in the control surface chain, though, must be better looking than a suspect link.

Also nice to learn about the stability / roll characteristics of weight below the wing. Suppose you have to mount a large mass right at the fore-to-aft CG, and have a choice of where to mount it from top to bottom? Where would be better if you want to maximize stability, and have no interest in rolling? As low as is feasible? A bit below the top-to-bottom CG? Above the CG (doubt it -- what happens though to stability when you lift the top-to-bottom CG)?

Thanks!
The stab to wing ratio was from something I thought I heard Ed say in a video. That was to make the stab about 1/2 the size of one wing (or 60/2/2=15) and the chord half of the stab length. And to also make the vert stab about half the length of the horizontal stab.

I'm no engineer, but I believe if you have your weight centered at the C.G. then when in a bank, you tend to hold the bank while falling, while a weight below the C.G. would tend to fall straight down resulting in a leveling action. I need an engineer to chime in here and explain how weight above and below the C.G. affects rolling moments.

Dave
Last edited by Backwall; Jan 31, 2013 at 03:57 PM. Reason: add chord info
Old Jan 31, 2013, 08:23 PM
syzygyQ is offline
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Quote:
Originally Posted by Backwall View Post
The stab to wing ratio was from something I thought I heard Ed say in a video. That was to make the stab about 1/2 the size of one wing (or 60/2/2=15)
Hmm. Yes, I remember Ed's video also. I believe he used a model built with one 30" wing section for his demo, and that we're meant to double the stabilizer size when using a 60" wing.
Last edited by syzygyQ; Feb 01, 2013 at 12:05 AM. Reason: focus
Old Feb 01, 2013, 01:29 AM
rcnewbieoz is offline
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Fan of experimetalairlines

My current build a boxy P-51


Thought I'd share a photo of my current build, it is based (loosely!) on a P-51 Mustang. I used the dimensions from a photo I found of the P-51, if you squint your eyes and dim the lights it sort of resembles one

I'm waiting on some parts so it'll be a few weeks before I get to maiden it.
Old Feb 01, 2013, 01:47 AM
Nightstone is offline
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20 years on the Internet
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Do yourself a BIG FAVOR and sell the DX6i. There is a big thread here in the forums on how they did elevons wrong on the DX6i. Even with the fixes the mixing is a nightmare. Add to that a slow recovery time if you get a disconnect and its just not a great reciever.

I got tired of it and picked up a DX8. Best decision I made in this sport. Brownouts eliminated. No more dicked up elevons.

Nightstone

Quote:
Originally Posted by Old_Robin View Post
I have built my first model (Snoopy) with Elevons and I have a Spektrum DX6i. I thought that my experience might be of use as I found the Spektrum manual as much use as a chocolate fireguard.
Elevons, for noobies, are two control surfaces at the back of the wing of a delta or flying-wing that serve as both elevators, by going up and down in concert, and as ailerons by one going up when the other goes down.
In the Set-up menu of the DX6i and other programmable transmitters (not simple ones like the DX4) there is an option of Wing Type. The options are for Dual Ailerons, Vee–tail, and Elevons.
If you complete the model and connect up the two servos, one plugged into the “aileron” and the other to the “elevator” output channel of the receiver, and do no programming at all then one of the control surfaces will wiggle up and down on the elevator stick movement and the other will wiggle when you use the aileron stick.
Go to the Elevons menu and make it “active” and both control surfaces wiggle when the Elevator or Aileron stick movement is used.
The ideal is that the control surfaces move together under Elevator, and that “pull back” moves them up. The aileron control should move the surfaces in opposite directions and the left surface should move up when the stick is moved to the left. You have a snow-ball’s chance in Hell of this occurring at first set-up, and this is where I had the trouble.
I found, by hair-tearing-out experience, that the best way to set up the Elevons was look at Elevator first. If these are not operating correctly go into the “Reverse” section and reverse the sense of one or both servos until the elevator movement is correct.
You are now way beyond the “Help” of the manual! You can RTFM as much as you like without success. I know.
Are the ailerons correct? Does left-stick raise the left control surface and lower the right surface. If so, you are allowed a conceited grin. If they are reversed THERE IS NOTHING YOU CAN DO WITH TRANSMITTER PROGRAMMING TO CORRECT THIS so do not spend a week (oops!) trying to work out how to do it.
If the ailerons are wrong it is logical that the “left” aileron and control surface has been put on the right side and the “right-side” aileron and control surface has been put on the left. By far the easiest way of correcting this is not to rebuild the model, but to swap the plugs over from the Aileron channel and the Elevator channel at the receiver output. This will have no influence on the proper operation of the Elevator, as they were both going in the same direction. However this will correct the Ailerons, which CANNOT BE DONE WITH PROGRAMMING, at least not simply on the DX6i as far as I can see.
One other point to mention, Elevons drive the servos with two stick channels simultaneously, so if you apply some elevator while on full aileron, you will exceed 100% travel. The actual travel comes from Pythagoras as they are at right-angles to each other so two inputs of 100% actually creates 141% of travel. This is considered socially unacceptable to servos which really do not like going above 125% of the “design” travel.
To be kind to the servos the rates on both channels should be limited to 80%, which squaring, adding and square-rooting gives 110% of travel maximum. If you would prefer to limit the throw to 70% on the two channels, this will be 98% of full throw on the servo at its maximum.
Sorry this is a long post, but I had some trouble finding the information and I hoped this might help another Noobie sometime. Happy Flying
Old Feb 01, 2013, 01:52 AM
Nightstone is offline
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20 years on the Internet
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Finished my replacement wing... No more flying low and hitting poles. Still cannot believe I did that.

Its built with a keel as all mine are now. Acts as a prop protector and landing gear. No stability issues with it. With the flat middle section there is alot of load variability. The 11x3 area can carry alot of equipment.

Last pic is of it sitting in front of my 60" Simitar Clone. Build pics in my blog.

Nightstone
Old Feb 01, 2013, 01:58 AM
Nightstone is offline
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Your builds always look so nice. I'm always afraid to so to much work on mine. Seems like the more work you put into it the more likely its going to crash in some freak accident.

I squinted and it looks more like a P-5?.

Nightstone

Quote:
Originally Posted by rcnewbieoz View Post
Thought I'd share a photo of my current build, it is based (loosely!) on a P-51 Mustang. I used the dimensions from a photo I found of the P-51, if you squint your eyes and dim the lights it sort of resembles one

I'm waiting on some parts so it'll be a few weeks before I get to maiden it.


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