Ventus 2cx 6-meter Build - Page 2

MTT · Oct 26, 2009, 08:32 PM

Quote:

I do not use a bell crank at all (which seems to be almost universally reviled) but rather a steel or "carbon" rod, held captive in a full-length sheath. The black Sullivan system is reasonable, but the only-to-be-found-in-Europe system is even better (it is a thin steel rod, encased in a plastic sheath, running inside of another, well-secured, plastic sheath).

Even worse than bellcranks, imho....

Even the very best bowden type pushrod, almost 2m long, and bent almost 90 deg to get to the t-tail, will have more slop and dead-band in it than a servo ( or servos ) mounted in the stab, with a short, direct link to the elevators.

Stop agonizing about the weight, and install 2 servos in the stab, with 2 separate leads ( + and - leads not ganged up ) to them, that will give you all the redundancy you need.

Other than that : what SteveR and Lbuff1 said !

GudmundT · Oct 27, 2009, 08:44 AM

OK, OK!!

You have almost (I can be quite stubborn when I want to be) convinced me to put the elevator servo in the tail, and SteveR’s suggestion of installing it in the horizontal stab (vice the vertical one) sounds like it is worth pursuing.

I also appreciate the logic of Lbuff1’s comment - If something happens to the elevator servo and disaster strikes, Then you get to start a new project.

I wonder, then, if I can leave the elevator issue for a while to explore the concept of redundancy.

Before I start, however, let me explain my perspective. The 5.14-meter Ventus 2c I am replacing failed to respond to radio signals when it was at 1,000 feet, pointed toward a major urban center. The potential disaster, had continued in that direction, is mind boggling. Thankfully, I was able to turn it through 180 degrees (or it turned itself?) and the model came to earth in a woods after flying a number of graceful circles.

So, the question is, how do I avoid a similar situation in the future?

I remember John Derstine, many years ago, talking of a gps unit that, if the radio link was lost, would fly the model back to the launch site and do flat circles till it came to earth. Something like that would, perhaps, be ideal. (I don’t mind the idea of the model crashing – see LBuff1’s comment above – I just do not want it to do so in a school playground!

So, how do you guys prevent fly aways?

Gudmund
Keep your tow lines tight!

s2000 · Oct 27, 2009, 08:55 AM

You might want to invest in a 2.4 radio system, scale gliders are a perfect platform for 2.4, since you have such a large area for antenna placement, I use the JR/Spektrum system since it allows for fine tuning of antenna placement with the Flight Log they have.

Sutton Bank · Oct 27, 2009, 08:58 AM

Gudmund,

I think all this great input will get you on the right lines. We tend to be quite an obsessive bunch, so it's easy to end up over-engineering our planes (I'm bad for this too!).

On my Schueler DG505 I went with a single rx, two batteries (Number One culprit for crashes) and a split elevator (2 servos in fin top with simple, strong direct drive) plus a vario, mostly for the voltage feedback.

I have no idea how to prevent flyaways, other than set your failsafe with something drastic like full airbrake/flap/rudder to get it down quick + nearby where you can at least shout a warning. Oh, and fly REALLY LOW all the time - then at least it won't go far (!)

Main thing - whatever you do - enjoy it.

Rog

SteveR · Oct 27, 2009, 09:40 AM

Rog's recco of a vario is a great idea as it will alert you in real time of any signal strength issues...at least that's the case with the Pic. Because when that vario voice starts saying "Attention...Attention" you know it's time to get down pronto while you still have a chance. Also, very helpful with battery voltage feedback.

And when you finally start to relax with your new bird, listening to the quick beep, beep, beep indicating a rising thermal will put a big smile on your face and make everything seem worthwhile!

Enjoy,

Steve

paul dufek · Oct 27, 2009, 11:42 AM

WhatSteve!! You don't like the Girl's sweet Voice!!L.O.L.

Paul

Bernd Brunner · Oct 27, 2009, 12:43 PM

Gudmund,

take a look at the weatronic system. It´s a full redundant 2.4 GHz system : 2Tx - 2Rx ... and they have gps assisted systems too.
http://www.weatronic-usa.com/index.p...d=27&Itemid=32
May be you can ask Joe Manor at the DS-forum about his experience - he is using weatronic too.

Bernd

GudmundT · Oct 27, 2009, 06:30 PM

Thanks Bernd.

That is going to take some study.

Gudmund

GudmundT · Oct 27, 2009, 06:41 PM

I have managed to get some building done.

The Phillips head screws that held the instrument pod in place have been replaced by magnets and a pin. It seems secure enough and it is real easy to take in and out.

I am a bit alarmed by the ease with which the paint chips off the pod. I may, in the end, want to remove all of the paint and apply something that actually sticks.

I have also repaired the canopy release mechanism. The simple task of gluing the mounting hardware for the handle didn't solve the problem. It was only when I managed to bend the wires just right that everything started to work smoothly. I do, however, need to cover the nut that is visible through the canopy, but I can do that cosmetically.

Gudmund
Keep your tow lines tight!

GudmundT · Oct 27, 2009, 07:37 PM

The retract is quite sophisticated, as it includes both a brake and a pair of coil springs (though they don't allow much movement - maybe I will try to replace them).

Unfortunately, and I have tried every possible way of mounting the servo, when the wheel moves up and down it rubs on the servo. This may not actually be a big deal, but I will try to eliminate it.

I now need to figure out how to put a fender onto the mechanism.

Gudmund
Keep your tow lines tight!

Lbuff1 · Oct 27, 2009, 11:01 PM

The wheel rubbing on the servo was the brake I thought?? just kidding, You are right, the paint comes off the pod if you look at it wrong, I like the magnet idea, I think I will do that to mine. I had no real problem with the canopy latch, evry once in a while I have to push it down a little to get it to latch.

len

GudmundT · Nov 07, 2009, 05:11 PM

I have now installed my variometer on the roof of the model, just behind the canopy, along with the total energy compensation probe. My bench tests suggests that it works.

I still need to install the socket that will connect the power/signal wire to the receiver, but that won't take long and I want to see where a few more components will be located before I do that.

My current vario is the Sky Assistant (altitude, climb rate, voltage and temperature).

Gudmund
Keep your tow lines tight!

Harm · Nov 08, 2009, 07:42 AM

I take it that you know this is the wrong TEC-probe for mounting on the fin. The one on the picture is ment to be mounted on top of the fuselage around one third the way between the wing and vertical fin.

GudmundT · Nov 08, 2009, 08:33 PM

Harm,

It looks good and it worked just fine with the Piccolario I had so I simply replicated it.

I am more interested in function than form.

Gudmund

MTT · Nov 08, 2009, 09:18 PM

Quote:

I am more interested in function than form.

That's why you should install the proper probe...
Harm is right, the one you installed is the probe designed to be installed on the fuselage, if you cannot install it in the vertical stabilizer..

From the skymelody website :
http://www.tek-variometer.de/englisc...tallation/body

Oct 27, 2009, 06:41 PM	#24
GudmundT Gudmund Join Date: Nov 2005 Location: Ottawa, Canada Posts: 87	I have managed to get some building done. The Phillips head screws that held the instrument pod in place have been replaced by magnets and a pin. It seems secure enough and it is real easy to take in and out. I am a bit alarmed by the ease with which the paint chips off the pod. I may, in the end, want to remove all of the paint and apply something that actually sticks. I have also repaired the canopy release mechanism. The simple task of gluing the mounting hardware for the handle didn't solve the problem. It was only when I managed to bend the wires just right that everything started to work smoothly. I do, however, need to cover the nut that is visible through the canopy, but I can do that cosmetically. Gudmund Keep your tow lines tight! Attached Thumbnails Two little magnets hold the rear of the instument pod. 29.7 KB · Views: 89 While a pin secures the front end. 27.3 KB · Views: 55 47.4 KB · Views: 66 The canopy lever needed to have the wires bent as shown before it would work without binding. 38.1 KB · Views: 90 I need to do something cosmetic about the ugly nut that will be visible through the canopy. 45.3 KB · Views: 69

Oct 27, 2009, 07:37 PM	#25
GudmundT Gudmund Join Date: Nov 2005 Location: Ottawa, Canada Posts: 87	The retract is quite sophisticated, as it includes both a brake and a pair of coil springs (though they don't allow much movement - maybe I will try to replace them). Unfortunately, and I have tried every possible way of mounting the servo, when the wheel moves up and down it rubs on the servo. This may not actually be a big deal, but I will try to eliminate it. I now need to figure out how to put a fender onto the mechanism. Gudmund Keep your tow lines tight! Attached Thumbnails As the wheel is retracted and extended, it rubs up against the servo. 40.1 KB · Views: 62 A nicely built retract with a pair of coil springs. 81.6 KB · Views: 59 And a brake. 58.8 KB · Views: 64 91.3 KB · Views: 62

Nov 07, 2009, 05:11 PM	#27
GudmundT Gudmund Join Date: Nov 2005 Location: Ottawa, Canada Posts: 87	I have now installed my variometer on the roof of the model, just behind the canopy, along with the total energy compensation probe. My bench tests suggests that it works. I still need to install the socket that will connect the power/signal wire to the receiver, but that won't take long and I want to see where a few more components will be located before I do that. My current vario is the Sky Assistant (altitude, climb rate, voltage and temperature). Gudmund Keep your tow lines tight! Attached Thumbnails This is the Sky Assistant velcroed to the top of the fuselage. The white line coming into the foreground is the tube that goes to the probe. 32.2 KB · Views: 43 Here is the aluminum probe I made mounted to the front of the vertical fin. 51.4 KB · Views: 31 And here is how it seals in the mount. 26.4 KB · Views: 39

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Oct 27, 2009, 08:44 AM	#17
GudmundT Gudmund Join Date: Nov 2005 Location: Ottawa, Canada Posts: 87	OK, OK!! You have almost (I can be quite stubborn when I want to be) convinced me to put the elevator servo in the tail, and SteveR’s suggestion of installing it in the horizontal stab (vice the vertical one) sounds like it is worth pursuing. I also appreciate the logic of Lbuff1’s comment - If something happens to the elevator servo and disaster strikes, Then you get to start a new project. I wonder, then, if I can leave the elevator issue for a while to explore the concept of redundancy. Before I start, however, let me explain my perspective. The 5.14-meter Ventus 2c I am replacing failed to respond to radio signals when it was at 1,000 feet, pointed toward a major urban center. The potential disaster, had continued in that direction, is mind boggling. Thankfully, I was able to turn it through 180 degrees (or it turned itself?) and the model came to earth in a woods after flying a number of graceful circles. So, the question is, how do I avoid a similar situation in the future? I remember John Derstine, many years ago, talking of a gps unit that, if the radio link was lost, would fly the model back to the launch site and do flat circles till it came to earth. Something like that would, perhaps, be ideal. (I don’t mind the idea of the model crashing – see LBuff1’s comment above – I just do not want it to do so in a school playground! So, how do you guys prevent fly aways? Gudmund Keep your tow lines tight!

Oct 27, 2009, 08:55 AM	#18
s2000 Registered User Join Date: Jan 2006 Location: so. cal. Posts: 1,029	You might want to invest in a 2.4 radio system, scale gliders are a perfect platform for 2.4, since you have such a large area for antenna placement, I use the JR/Spektrum system since it allows for fine tuning of antenna placement with the Flight Log they have.

Oct 27, 2009, 08:58 AM	#19
Sutton Bank Registered User Join Date: Oct 2007 Posts: 58	Gudmund, I think all this great input will get you on the right lines. We tend to be quite an obsessive bunch, so it's easy to end up over-engineering our planes (I'm bad for this too!). On my Schueler DG505 I went with a single rx, two batteries (Number One culprit for crashes) and a split elevator (2 servos in fin top with simple, strong direct drive) plus a vario, mostly for the voltage feedback. I have no idea how to prevent flyaways, other than set your failsafe with something drastic like full airbrake/flap/rudder to get it down quick + nearby where you can at least shout a warning. Oh, and fly REALLY LOW all the time - then at least it won't go far (!) Main thing - whatever you do - enjoy it. Rog

Oct 27, 2009, 09:40 AM	#20
SteveR Registered User Join Date: Feb 2002 Location: New York Posts: 1,868	Rog's recco of a vario is a great idea as it will alert you in real time of any signal strength issues...at least that's the case with the Pic. Because when that vario voice starts saying "Attention...Attention" you know it's time to get down pronto while you still have a chance. Also, very helpful with battery voltage feedback. And when you finally start to relax with your new bird, listening to the quick beep, beep, beep indicating a rising thermal will put a big smile on your face and make everything seem worthwhile! Enjoy, Steve

Oct 27, 2009, 11:42 AM	#21
paul dufek Registered User Join Date: Oct 2005 Location: cathlamet.washington Posts: 208	WhatSteve!! You don't like the Girl's sweet Voice!!L.O.L. Paul

Oct 27, 2009, 12:43 PM	#22
Bernd Brunner dare to thermal Join Date: May 2004 Location: Mannheim, Germany Posts: 279	Gudmund, take a look at the weatronic system. It´s a full redundant 2.4 GHz system : 2Tx - 2Rx ... and they have gps assisted systems too. http://www.weatronic-usa.com/index.p...d=27&Itemid=32 May be you can ask Joe Manor at the DS-forum about his experience - he is using weatronic too. Bernd

Oct 27, 2009, 06:30 PM	#23
GudmundT Gudmund Join Date: Nov 2005 Location: Ottawa, Canada Posts: 87	Thanks Bernd. That is going to take some study. Gudmund

Oct 27, 2009, 11:01 PM	#26
Lbuff1 Registered User Join Date: Nov 2008 Location: Killingworth CT Posts: 482	The wheel rubbing on the servo was the brake I thought?? just kidding, You are right, the paint comes off the pod if you look at it wrong, I like the magnet idea, I think I will do that to mine. I had no real problem with the canopy latch, evry once in a while I have to push it down a little to get it to latch. len

Nov 08, 2009, 07:42 AM	#28
Harm Registered User Join Date: Jan 2004 Location: Holland Posts: 163	I take it that you know this is the wrong TEC-probe for mounting on the fin. The one on the picture is ment to be mounted on top of the fuselage around one third the way between the wing and vertical fin.

Nov 08, 2009, 08:33 PM	#29
GudmundT Gudmund Join Date: Nov 2005 Location: Ottawa, Canada Posts: 87	Harm, It looks good and it worked just fine with the Piccolario I had so I simply replicated it. I am more interested in function than form. Gudmund