Element 2 pure glider

[Glenn Beer]

Would 2 deg. up elevator be a good starting place to set the elevator neutral on the Element 2?
(Two with respect to the bottom of the wing.)

Id rather not have my first launch end up in a bonk.

 

[Konrad]

What is an Element 2?

CLM PRO Element 2m Pure Glider REF ARF

NOT FINISHED !!!The Element 2 Glider comes in Red with Yellow Tips.CLM Pro has released a new model called Element 2. This is a very light weight REF thermal ship (approx 285g empty airframe weight) and it is very stable and a joy to fly. The model is constructed using judicious use of carbon...

alofthobbies.com

But no. Most folks like a setting of 0.5° to 1.5° decalage. If the airfoil is a flat bottom this matches pretty close to having the stab chord line parallel with the bottom of the wing (wing chord line positive 1.5°+ for most airfoils).

First launch should be a hand toss across the football green to set trims.

There's nothing in the documentation?

 

[Glenn Beer]

What is an Element 2?

CLM PRO Element 2m Pure Glider REF ARF

NOT FINISHED !!!The Element 2 Glider comes in Red with Yellow Tips.CLM Pro has released a new model called Element 2. This is a very light weight REF thermal ship (approx 285g empty airframe weight) and it is very stable and a joy to fly. The model is constructed using judicious use of carbon...

alofthobbies.com

But no. Most folks like a setting of 0.5° to 1.5° decalage. If the airfoil is a flat bottom this matches pretty close to having the stab chord line parallel with the bottom of the wing (wing chord line positive 1.5°+ for most airfoils).

First launch should be a hand toss across the football green to set trims.

There's nothing in the documentation?

Yes, that is the glider.

No documentation came with the glider. And I’m not finding any online, nor any build logs. That ”Element“ seems to be one of those names that generates a lot of chuff during searches doesn't help.

 

[Konrad]

No documentation, that's a crime!

I recall guys here starting with 60mm as the CG and moving it aft after the first few trim flights. I don't recall ever seeing an elevator rigging number (just hand toss it across a few soccer fields, I mean a FEW as she will glide forever in ground effect)!

I see that CLM Pro has a vendor forum on RCGoof's

CLM Pro - RC Groups

We are manufacturing composite parts, mainly for RC models and model composite accessories. We are currently concentrating on composite Pods and fuselages but are expanding our production. www.clm-pro.com/en

www.rcgroups.com

 

[Glenn Beer]

I received this from Nicola.

Since the whole elevator area is movable it doesn't have to move much to me maneuverable. So just start with small steps.
You can use a 45° (offset?) to each side for rudder.
You have to set up and trim the model a bit, but once it's done it flies like a beaut. Neutral on elevator can be defined as parallel to wing main section,so its in a line with the wing.

Element 2 CG is 30-35% from the leading edge, that is, 54 to 63mm, or if you want it to be more agile, you can put it 10mm behind, but the model get a unstable then and is pretty hard to fly.

Kind regards,
Nikola

 

[Konrad]

Nikola is, the designer?

I'm glad he concurs with me about being flat with the bottom. I too try to get all I can from the rudder +45°.

I don't agree with the statement about full flying elevators. For the same control power, I find that I need more movement with full flying elevators than with camber changing control surfaces. What I find is that the full flying surface causes less drag in the trim state and at low control inputs.

Do try the aft CG trim. But when you do be prepared to cut down on the amount of throw needed. Don't confuse unstable (divergent) flight with over controlling from too much control movement.

All the best,
Konrad

 

[Glenn Beer]

Nicola is who replied to my questions submitted at the clm-pro website.
I have flown it at The 60mm GC location. The dive test was very neutral.
Level flight seemed slow.

 

[Glenn Beer]

Update:
Cut the nose off and installed a Hacker A10-L7 4.4:1 geared motor, a 30mm spinner, 13x8 prop and a luminair 30a esc with BEC.
Such a small motor for a 13 in prop. It works well, with a 3cell 950mah, it pulls the element 2 nicely to alt. All up weight is now 520g.
Flew today, specked out on one flight, on the second I kept finding just enough lift. The plane indicated lift much better than all my recent fliers.

 

[Konrad]

I'm in the process of doing the same thing with a DJAerotech F3-RES Chrysalis, but with a high "C" rated 450 battery. How many climbs do you think you can get with the 950 mAh battery? I'm hoping 3 with my light weight set up.

 

[Glenn Beer]

I’m getting 3.5 minuets of runtime with a over 30% remaining in the battery.

ps. The first climb to 100 meters takes about 30sec.

 

[Konrad]

Thanks.

So that's about 7 climbs. I don't think I need or want that much energy on board.

 

[Glenn Beer]

I still had to add ballast even with the 950mah battery. So no point in lofting a smaller capacity battery.

 

[Konrad]

Good to know. I'm actually extending the nose on my F3-RES Chrysalis lite to try to get rid of some dead weight.

 

[Glenn Beer]

Just to put the info down. The firewall I installed has 4.3deg down thrust. It could maybe use a bit more.

 

[Konrad]

Wow! Does the model dive when power is initiated? That does sound like a lot of down thrust. I wonder if it is hampering the climb rate?

 

[Glenn Beer]

Actually, I’ve (re)installed the firewall 3 times. At full power, without correction, the sailplane climbs into a full loop. It took about 80% down elevator to get a good climb out. The 2nd install added ~2deg down thrust, that brought the elevator correction down to about 25% down, the third install still requires a small amount of down elevator.
These measurements are relative to the fuselage bottom. I haven’t measured it to the wing yet.

 

[Konrad]

Wow, thanks.
I normally like a bit of elevator comp to my motor mix. But if you are that sensitive to speed I think you might be real nose heavy. I'll use 2.5 degrees of down thrust. If I need more, then I'd start to look elsewhere for a trim issue.

To find thrust line trim, I'll trim for level flight at full power. Then suddenly chop the power. If at the moment the power is chopped the model jumps up I have too much down thrust. If the model tucks a bit (dives) I have too much up thrust. This is all done without elevator comp.

This is a flat bottom airfoil? Some banana airfoils just can't be trimmed properly.

All the best,
Konrad

 

[Wayne]

I think this really is a personal style issue. For thermal ships I actually like a plane to climb some when the motor is on. That is why I have the motor on a thermal glider. For other powered aircraft I do not like them to climb under power, and will adjust motor angle if needed.

 

[Konrad]

Climb (gain altitude) is different than attitude change like a loop! So yes, there is a personal style component but there is also a proper trim setting. A looping or diving model on power up is just poor trim.

 

[Konrad]

Well, well, it looks like owe Glenn an apology. I too have a light ship with a huge prop disk area, much the same power system. With my ship at close to neutral trim (by the dive test method) I too am carrying close to 8° of down thrust.

I'm at a loss as to why. Might it be some relationship between the disk area, center of drag, power loading and thrust line?