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Apr 25, 2007, 12:22 AM
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Discussion

SuperGee II continued (thread #5)


Welcome to thread #5, continuing our collaboration in building and flying Dr. Mark Drela's SuperGee II DLG (discus launch glider).

To follow the discussion from the beginning, learn building, setup, and flying tips, and get a good introduction to the Super Gee II, see this and the previous threads:
SuperGee
SuperGee II (continued #2)
SuperGee II (continued #3)
SuperGee II (continued #4)

Graham Allen's Super Gee II

Why build a SuperGee II?

Anyone wanting a composite 1.5 meter glider has a decision: Buy a completed glider, assemble one from parts, or build one from scratch.

In October 2001, Dr. Mark Drela released his plans for a lightweight, high performance hand launch glider designed for discus launching. Thereafter he released plans for a second version with modifications that improved the design, particularly with at-home builders in mind.

The SuperGee II offers superb flying performance, extreme light weight, elegant and functional design, and a enthusiastic community of home builders. Modern discus launch gliders take inspiration from the design. A typical competition-class DLG made today uses it's blended airfoil series or some variation thereof.

Procuring a glider in kit form, or making your own, hand launch pilots have outstanding options available. The choices seem to keep on getting better.

Where can I find information on building the SuperGee II?

There are three primary sources of information on the glider. For the plans and the option of digital airfoil files, go to the Charles River RC website.

For historic discussion and valuable files about composite construction, join the Yahoo Group SALGlider.

For continuing discussion and in-depth sharing of technique, this series of threads on RC Groups is the best.

For a step-by-step builders guide, see the ongoing project on RCBuilder.com.
Construction documents are in development in the Super Gee II Builder's Guide. Contributions of step-by-step instructions are appreciated by all.

Once you have SG-II components built, the LightHawk Assembly Guide (written for a commercial design based on the SG-II) is an excellent tool for finishing your glider.

All are welcome to this thread discussing the Super Gee II.


At the ocean: Graham Allen's (Salto) Super Gee II


Jeff and Graham, Australia


Jeff (jirvin_4505) and his SG2


Viktor (ViktorF) and glider, Russia


Viktor's SuperGee II


Curtis Miller's Super Gee II


Raphael Jeger's Super Gee II, Switzerland


A familiar and treasured view for Super Gee II Builders
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Apr 25, 2007, 06:02 PM
VHO
VHO
glider misguider

Non scale SG2 wing layup


ASK,

Thanks for this great series of threads. Love my SG2. It flies very well.

It seems almost sacreligious to ask this question first up in thread #5 but ...

I am building a SG2 wing to put on a Tabooish fuse and tail feathers. It will be my first wing build, and am considering the following changes, mainly in an effort to cap weight (I am unsure of the structural implications).

1. Flaperon doublers - 3/4oz glass (at 45deg) slightly larger than plan.
2. Centre doublers - 1 layer of 1oz Kevlar (rather than 2). I won't be using pylon mount or RDS so consider the additional reinforcement may not be required (no hole through the wing to contain the RDS drive system stronger skins to compensate).

Haven't found anything specific in threads 1-4 but there seems to be a lot of people with experience with different wing layups that could assist.

I just happen to have made a bunch of Tabooish pods and have tail booms to suit so want to see if there is a difference in launch height / performance due to different tail feathers / moment.

Hutton
Apr 25, 2007, 08:42 PM
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Quote:
Originally Posted by VHO
...I am building a SG2 wing to put on a Tabooish fuse and tail feathers. It will be my first wing build, and am considering the following changes, mainly in an effort to cap weight (I am unsure of the structural implications).

1. Flaperon doublers - 3/4oz glass (at 45deg) slightly larger than plan.
2. Centre doublers - 1 layer of 1oz Kevlar (rather than 2). I won't be using pylon mount or RDS so consider the additional reinforcement may not be required (no hole through the wing to contain the RDS drive system stronger skins to compensate)... I just happen to have made a bunch of Tabooish pods and have tail booms to suit so want to see if there is a difference in launch height / performance due to different tail feathers / moment.
Hutton,
I'll offer some guesses.
1) This ought to work fine. In the worst case you would just face the flaperons and stiffen them that way.
2) If you are going to cut servo bays in this area, I'd consider using two doublers both top and bottom.

You aren't changing your test focus much (affect of tail feathers / moment) by laying in additional center reinforcement. You are adding a little weight, but if you are using 1 oz. sq yd / 36 g sq meter aramid skins, the second doublers seem more than prudent to me.

LightHawks (variation on the SG2 theme) use a second doubler and no wing joiner, and they also have 1.7 oz. aramid skins.
Apr 26, 2007, 12:22 AM
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ASK,
Thanks once again for maintaining these threads. It's a great thrill to see Supergees from all over the world looking almost identical. I keep seeing the other pictures and thinking they are my model.

Hutton,
What ASK just said.

The bending loads on the wing are taken by the spars, so the Kevlar doublers would be mainly there to reinforce the skin against wing torsional loads around the RDS installation, and to take the loads from the wing pylons, neither of which you will have. But I assume you will still have to place wing servos somewhere? In which case you'll still need equivalent reinforcement.

The alternative would be to place the wing servos further out where the skin loads will be lower, in which case you may get away with less reinforcement, and which would also let you reduce the flaperon doublers, but this would be a retrograde step in terms of yaw inertia.

If you place the wing servos inboard like on the plans, then for an extra couple of grams I'd still use the 1 oz Kevlar flaperon doublers. Some people have reported flutter problems if the flaperons are not faced, so it looks like things are marginal here. Also, I suspect that you can get 1 oz Kevlar a lot dryer than 3/4oz glass without running into white dry patches, so I don't think using the glass would save that much weight anyway.

Jeff,
You sent THAT picture to ASK !! What a pair of Supergee nuts we look. By the way people, I'm the handsome one.

Graham.
Apr 26, 2007, 08:15 AM
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I need a little help with my SuperGee Variant. ASK recently sent me the PDF file for setting the EVO per Mark's specifications for the SuperGee. I entered everything carefully and I'm close to everything working as desired. However I do have a couple of problems that I can't figure out. I've double checked my entries and everything seems correct, but I'm still an EVO rookie so I must be missing something. My main problems are:

How do I get the flaps to be at neutral when the throttle stick is all the way up? After setting up per Mark's PDF, the flaps are neutral when the throttle stick is in the middle. Half the throw is above neutral and half below. I need the flaps neutral when the stick is all the way up and all the throw below neutral.

The PDF mentions flattening out the aileron curves (no more downward movement) when the flaps are fully deployed. Is this done in the calibration menu? If not there, where?

My last problem is the launch preset button. It's set up on the momentary switch "M". How do I set the launch trims? I tried holding down the button and changing trims, but that didn't work. Am I supposed to go to a menu to set the trims when I hold the "M" button for launch?

Thanks in advance!
Apr 26, 2007, 08:49 AM
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Quote:
Originally Posted by Jim Walker
How do I get the flaps to be at neutral when the throttle stick is all the way up? After setting up per Mark's PDF, the flaps are neutral when the throttle stick is in the middle. Half the throw is above neutral and half below. I need the flaps neutral when the stick is all the way up and all the throw below neutral.
This is mechanical, inside the radio. See the EVO manual for changing the left stick. I don't remember off-hand how it's done, just that you adjust some screws.

Quote:
The PDF mentions flattening out the aileron curves (no more downward movement) when the flaps are fully deployed. Is this done in the calibration menu? If not there, where?
Yes, in the calibration curves for the two servos.

Quote:
My last problem is the launch preset button. It's set up on the momentary switch "M". How do I set the launch trims? I tried holding down the button and changing trims, but that didn't work. Am I supposed to go to a menu to set the trims when I hold the "M" button for launch?
See the Mixer menu->Elevator->Spoiler and Mixer menu->Rudder->Spoiler. Adjusting these give you the amount of throw when you press M.
Last edited by ASK; Apr 26, 2007 at 10:03 AM. Reason: Finishing question on M button
Apr 26, 2007, 08:53 AM
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Quote:
Originally Posted by Jim Walker
My last problem is the launch preset button. It's set up on the momentary switch "M". How do I set the launch trims? I tried holding down the button and changing trims, but that didn't work. Am I supposed to go to a menu to set the trims when I hold the "M" button for launch?

Thanks in advance!
Jim,

Have you used the M button to trigger a different flight phase? If so, then you should simply be able to hold down the button and change the trims to suit (since trims are stored with each flight phase). See Section 7.3 of the EVO Tutorial ("Flight Phase Definition"). There are other ways to do this, such as using the M button to change a Rudder mixer (see section 14.3 in the tutorial for this case). I use the flight phase method...

Sorry, I can't help with flattening out the aileron curves, I've not tried that.

I know that I've got the flaps working properly on the left stick but unfortunately I don't have my radio in hand to check the settings. I beleive that you need to set the input to your aileron mixer to be "single sided with offset" like the Aileron+ mix shown on page 12 of the tutorial.

If you've not checked the EVO Tutorial, then you should take a look at it (Multiplex EVO Tutorial . It is pretty much a required supplement to the manual, I've run into problems that I couldn't figure out from the manual and ended up finding the answer in the tutorial.

73 John
Last edited by jvander; Apr 26, 2007 at 08:56 AM. Reason: added info on rudder mix
Apr 26, 2007, 09:01 AM
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Thanks for the quick reply Aradhana.

So you're saying that a person has to adjust the POT in relation to the stick movement mechanically inside the transmitter? Wouldn't that make the throttle stick unusable in the application it was designed for, namely the throttle on a powered model?

Thanks for the extra effort of remembering the how when you get back to the shop.

Jim
Apr 26, 2007, 10:12 AM
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Quote:
Originally Posted by Jim Walker
So you're saying that a person has to adjust the POT in relation to the stick movement mechanically inside the transmitter? Wouldn't that make the throttle stick unusable in the application it was designed for, namely the throttle on a powered model?
On the contrary. The Evo comes with factory defaults of the left stick centered and with springs activated to return it to center. You want no springs, a little bit of the ratcheting thingy (Not the correct terms ) activated so the stick stays where ever you leave it, and the stick at the top for "no flaps" / stick at the bottom for full flaps.

That's the same configuration you want for throttle, except that up is full throttle, and down is no throttle. You do that with a different template, I think.
Apr 26, 2007, 10:57 AM
Registered User
Jim,

This is how I have my Evo set up. It's cleared up a lot of problems for me that I had when I tried Mark's set up. It works for him, and lots of others, but I had continual trim problems.

First: The flap set up. I have mine set up so that the flaps begin as soon as the stick passes the neutral point, heading in a back position. This allows all rudder movement to be done with the stick in the neutral or forward position without introducing camber.

No fiddling with the stick POT unless you want to get rid of the "ratchet" feeling.

Trims: I set up three phases, controlled by whatever widget controls the camber. This makes all trims independent for each camber position.

Presets: Elevator and rudder presets are controlled by the offsets associated with the widget used for the preset. Just be careful and don't accidentally use a preset for the off (normal) preset of the widget.

By the way, a useful change to the stick pots is to change the orientation of the axis to be slanted so that applying aileron doesn't also apply some up/down elevator. When I hold my Evo, the pivot point of my thumb is on the corner of the case, not directly below the stick, so this is useful to me. How to do this is described in the manual.

If this helps, and you are interested, I'll be glad to get the Evo out and go thru it.
Apr 26, 2007, 11:01 AM
Flying IS the hobby
Quote:
Originally Posted by Jim Walker

How do I get the flaps to be at neutral when the throttle stick is all the way up? After setting up per Mark's PDF, the flaps are neutral when the throttle stick is in the middle. Half the throw is above neutral and half below. I need the flaps neutral when the stick is all the way up and all the throw below neutral.
Thanks in advance!
Maybe I am wrong, but I don't think Jim is referring to the radios factory setting of the left stick, which is covered on pg. 10 of the manual.

From the description above it also sounds the servos where inserted in the wing with the servo arms centered, when they should be slightly offset, to accommodate for the extra run when engaging full flaps.

While calibrating servos, make sure the stick is all the way up.

You'll use the Servo Calibration and Mixer Aileron+ to center servos and eliminate any flap upward movement when the left stick is set all the way up.

enabling the ratchet option in the left stick is covered in page 10 of the manual

Jose
Apr 26, 2007, 11:01 AM
Registered User
David Forbes's Avatar
Curtis,
Check page 58 of the manual for the correct symbol, it's in the aileron + mixer where you define the single sided with offset travel for the left stick. Stumped me too when I set mine up.
Dave
Apr 26, 2007, 11:56 AM
Registered User
Hold on guys. Jim just got a bunch of conflicting pieces of advice.

I think Jose is right -- the servos are installed centered when the flaps are neutral.
This is not good for a number of reasons:
Insufficient down travel
Excessive up travel
Flaps deflected up with stick all the way forward.

This rigging method works:

If using a horn:
With the servo centered (stick in the middle, no trim offset)...
- Attach servo arm perpendicular to chordline
- Hook up flap linkage so that flaps are about 20 deg down

If using RDS with yoke:
With the servo centered (stick in the middle, no trim offset)...
- Attach servo arm parallel to chordline
- Attach wiper to arm and yoke so that flaps are about 20 deg down


With the stick forward, the flaps should now be close to neutral.
Fine-tune the flap positions with servo response curves or with sub-trims,
depending on radio.
Apr 26, 2007, 12:28 PM
Fixed Wing Fanatic
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I apologize, obviously I didn't make my problem easily understood. Let me try to say it in a different way.

The first thing I did when I got the EVO was to disengage the centering spring on the left stick vertical axis and engage ratcheting. That's not my problem.

The flap problem could be broken down into two seperate problems. First, to get the flaps neutral to the wing, (no camber or reflex), the throttle stick must be centered as things stand now. The desired position with Mark's transmitter setup is for the flaps to be neutral to the wing when the throttle stick is fully up/pushed away. I thought there was some mix setting or menu setting that should be able to accomplish this, but I'm not sure and I couldn't figure it out last night.

Second, when I move the throttle stick up from centered, the flaps reflex and half the flap throw is in the upward direction. I need 100% of the throw to be downward as I move the stick down/pulled toward myself. I'm pretty sure these two problem are closely interrelated, but I'm not sure where to correct it in software.

Thanks for the responses concerning presets on the M switch. Looks like there's a couple of ways to skin the cat and I'll try both and see which I like best. Thanks for all the responses so far and future ones till I get this ironed out. I'm trying to get this dialed in before this weekend's contest in Albuquerque.

Addendum-

Apparently while I was typing this message Mark beat me to the punch and answered my question. Thanks Mark and Jose!!! I guess I'm going to have to redo my linkages tonight.
Last edited by Jim Walker; Apr 26, 2007 at 12:34 PM.
Apr 26, 2007, 01:07 PM
ASK
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Here are some photos showing the assembly steps where you set the wipers for an RDS. They should inform the points Mark is making. Note that I usually use less throws than Mark, so where he says 20 degrees, I say 15 degrees. If in doubt, use Mark's numbers.

https://www.rcgroups.com/forums/show...20&postcount=2


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