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Old Jan 27, 2008, 11:51 AM
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globalarray's Avatar
Louisville, KY
Joined Dec 2007
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I don't recall any flutter. I'll find out in a couple hours after I fly it this afternoon. Normally if there's any at all it can be heard 1/2 mile away.
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Old Jan 27, 2008, 02:31 PM
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DanT's Avatar
San Angelo TX.
Joined Feb 2006
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My friend has been in Rc for over 30 years who told me about the elevon and elevators. He has made hundreds of airplanes and reads most of the RC magazines .
I doubt he could point us to a book? I can tell you it worked for me. I also am trying more setup for fun. If the flutter comes back, I will let you all know.. Oh, remember my setup is not EPP so I doubt you can hear flutter when made out of EPP?
And my setup is fast in a dive at 12.5 oz. I couldn't hear it, I could see it. I do high speed passes about 10' from me all the time.. \
Here is some more testing when I get the time..
Oh, I'm getting about 16 minutes of hard flying time using my TP 1320 3 cells. One friend asked me if I was using solar panels !
And my battery reads about 11.3 volts.
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Last edited by DanT; Jan 27, 2008 at 02:49 PM.
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Old Jan 27, 2008, 04:13 PM
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London, UK
Joined Nov 2006
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Just curious Dan,as I have been modelling for a long time too and its the first time I had heard the tip.
However I don't doubt that theres a good reason to back it up.
Keep us posted always in the market for good info.....
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Old Jan 27, 2008, 06:49 PM
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San Angelo TX.
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Quote:
Originally Posted by dekan
Just curious Dan,as I have been modelling for a long time too and its the first time I had heard the tip.
However I don't doubt that theres a good reason to back it up.
Keep us posted always in the market for good info.....
I was also told ( by another old friend ) if you don't round the back edge of control surface (like I did ) it helps stop flutter also. My friend said to leave it at 90 degrees .
I was looking at some of my airplanes ( kits) and two have a counter weight setup and they both have tapered outside tips. I fly these very hard and fast with no flutter.
Pictures attached .
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Old Jan 27, 2008, 07:07 PM
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Louisville, KY
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I flew this afternoon and I wouldn't be able to tell if it fluttered or not with 20mph gusts with a 10oz plane. I wish I had some video of it rolling and looping away from me, sure is fun!
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Old Jan 27, 2008, 07:11 PM
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If control surfaces are properly counter-balanced, either static or aerodynamic, you won't get flutter. On a flying wing, the reason it's better to have the tips of the control surfaces thinner than the root is that the wings can flex with the control loads which is what causes the flutter in the first place. I noticed this a long time ago with overpowered Zagis literally fluttering to destruction. From experimentation I found that this tendency is much reduced with less area at the tips.

BTW - DAN, I originally designed the Super Cutlass with control surfaces shaped exactly like you have now. TOMCOR took the liberty to change them thinking he'd get better roll rate which may be true but with a flexable wing tip it's risky and not really necessary with the short span of these little planes.
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Old Jan 28, 2008, 01:02 AM
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London, UK
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Thanks for the Info Ken.
Dan. a lot of Free flight competition models have blunt trailing edges.
When ever I have asked I been told "the airs done its job, why care what happens to it once it's left the wing." I wondered about that statement.......
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Old Feb 17, 2008, 05:51 PM
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Dan, I looked over your posts and running heavy like you are, you really should add the diagonal rods as Tomcor did to the original. I'm sure you're getting the flutter for the tip flex on the wings fighting the control surface deflection. I don't think the extra elevon area at the tips helped and at speed even the smaller elevons may still do it only less?

dekan - I think the thing with rounded vs blunt TEs is only a matter of drag. Some say that the small vorticies created from them being blunt help things like rocking and such so may not be worth worrying about unless you need every bit of speed you can get from a plane.
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Old Feb 17, 2008, 07:54 PM
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San Angelo TX.
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I have stopped the flutter now by cutting down the glued on pieces a little bit .
I don't think the flutter is being caused by not having diagonal rods . All of my setup is very strong with dubbed 3mm foam.
I'm also thinking about going to a much larger motor setup for greater speed.
I could move a bigger motor forward to make the cg. The motor I have sitting around not doing anything is a Hacker 20 20 L 1000kv with the right prop it could push this wing over 60 mph. But I'm not going to do it right now.
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Old Feb 25, 2008, 01:22 PM
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Here is the video from my yesterday flight:

Cutlass Park Flyer (3 min 26 sec)
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Old Feb 25, 2008, 02:15 PM
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Joined Jul 2006
56 Posts
Tryed mine (mini cutlass version EPP 6mm) but not happy with it, perhaps overweight.
Any advice to counteract the bad tendency to fly upside down on launch and impossiblity to turn left after
Equipment : BW 1300 - 3S 460 mAh - prop GWS cut 5X6 - 2 servos 5 g - Esc 12 A - Mpx receiver RX5 -

Exact total weight unknown but surely heavy for that size.

Dom
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Old Feb 25, 2008, 02:32 PM
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London, UK
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A standard BW 1300Kv will not produce very much power even on 3s with a 5x5 prop. The prop of choice is an 8x4

See the chart below. I think these are Gene Bond's figures
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Old Feb 25, 2008, 03:27 PM
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Joined Aug 2007
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My setup for mini Cutlass (depron 6mm - wing made double):
- AX 1806N 2100kv Brushless Micro Motor (19g)
- TowerPro 9g w12A Brushless Speed Controller
- 2x HXT900 9g / 1.6kg / .12sec Micro Servo
- BA-R3P6 H/T V3 FM 6-channel Micro Receiver
- hexTronik D9 gen2 620mAh 2S 15-20C Lipo Pack
- prop. GWS 7x3,5 HD

Ready to fly weight is 186gr. (about 6 oz. ?)

Quote:
Originally Posted by PandaE
Tryed mine (mini cutlass version EPP 6mm) but not happy with it, perhaps overweight.
Any advice to counteract the bad tendency to fly upside down on launch and impossiblity to turn left after
Equipment : BW 1300 - 3S 460 mAh - prop GWS cut 5X6 - 2 servos 5 g - Esc 12 A - Mpx receiver RX5 -

Exact total weight unknown but surely heavy for that size.

Dom
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Old Feb 26, 2008, 02:03 PM
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Dekan
Problem is not a lack of power with BW, but an impossibility of maintaining wings
level.
Marek
Thanks for details of your setup

Dom
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Old Feb 28, 2008, 05:48 AM
Build 2 Bounce!
Birmingham, UK
Joined Jul 2006
1,660 Posts
Dom, It sounds like you've either got problems due to lateral balance, thrust line or motor torque.

My first thought would be to make sure (looking at the model from the back) that the motor doesn't have any right thrust built in. Then check the balance and if necessary move the battery to the left help counteract the torque from the motor. Also, test glide the model without power to see how it behaves.

HTH,
Si.
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