TuffFlight Predator X Wing Flutter...  
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TuffFlight Predator X Wing Flutter... - 10/24/2004 10:04:38 PM   
glowplugboy


 

Posts: 580
Joined: 12/26/2001
From: Pasadena, TX 77505/77508, TX, USA
Status: offline 		Another problem. I have a Predator X set up for OPEN B. I am getting some wing twisting that is noticeable from the ground. The twisting is causing the wing to be in a left hand turn. Clearly, I am not stiffing something enough, and tape covering is not holding well to the EPP, even with 3M77. What should I do!

Many thanks for your help,
GPB
       Post #: 1

RE: TuffFlight Predator X Wing Flutter... - 10/25/2004 4:36:07 AM   
wind junkie



Posts: 1002
Joined: 11/16/2002
From: N. Syracuse, NY, USA
Status: offline 		Did you mean you're using TAPE for covering? That would be bad. Only Ultracote or Icarex should be used. Anything else and who knows what will happen.

That big wing needs a lot of attention to keep it straight. Check the directions for how to trim the plane. You first need to get the roll trim even. Most likely there is a slight warp ironed into your wing. This will show up as unwanted roll trim that changes with airspeed. In that case you'll need to twist it in the opposite direction and iron it straight, one wing half at a time.

After the roll trim is good, then you can worry about washout or wash in using the same method.

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RE: TuffFlight Predator X Wing Flutter... - 10/25/2004 4:53:50 PM   
Montague



Posts: 4655
Joined: 4/19/2002
From: Laurel, MD,
Status: offline 		Most Predator X's I've seen could go in to wing flutter at very high speed. I like to do a series of high speed vertical dives to get away from them. Even covered in Ultracote, they can flex a lot. I haven't seen an Icrex covered one doing high speed dives yet, so I don't know if it's possible to get one to stop flexing.

fwiw, tape can create as much or more tension as Ultracote if you put it on well. Many tapes will also shrink some with a sealing iron, allowing you to tighten it up some and get it to stick better. Try going over the plane with an iron if the tape is coming unstuck.


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RCCA 560

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RE: TuffFlight Predator X Wing Flutter... - 10/25/2004 6:19:12 PM   
glowplugboy


 

Posts: 580
Joined: 12/26/2001
From: Pasadena, TX 77505/77508, TX, USA
Status: offline 		Hi again, Kirk,
I used 3M77 as a base to stick packing tape initially for the covering. When I peeled the covering off last night, only about 25% of the tape was well adhered to the wing, and I did use an iron to furhter assist in it sticking to the EPP. Apparently the adhesive on the tape did not mix well with the 3M 77.

I did a test piece of EPP foam with Sig Koverall and 3m 77, and it worked great! After curing I went over it with an iron on high and the Koverall shrunk nice and tight, very smooth, AND it added lateral rigidity. If you don't know what Koverall is, it is a polyester based fabric that is used on giant scale models. Very tough, and similar to the Icarex (I hope that's spelled right).

Regards again,
Mike

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RE: TuffFlight Predator X Wing Flutter... - 10/25/2004 6:25:47 PM   
Montague



Posts: 4655
Joined: 4/19/2002
From: Laurel, MD,
Status: offline 		Interesting. Sounds like you have a good fix there.

Btw, what brand tape were you using? I've found that not all tapes stick alike, not even close. I really prefer "Uline" brand, I find the sitckum is much more aggressive and it shrinks better than scotch/3m tapes. The tape I use is about 2mil thick. I use it on all my planes now, but I don't have any EPP wings, so I don't know for sure that it would get the job done on something like a Predator X.


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RE: TuffFlight Predator X Wing Flutter... - 10/25/2004 6:39:42 PM   
NAES



Posts: 64
Joined: 2/27/2004
From: , CA, USA
Status: offline 		I have been using an X for combat for the last 6 mos or so. Covered in Ultracote I have had zero issues with wing twist or flex. I definitely loaded the wing up w/3m77 and let it set up. I also put bidi tape over the spar top and bottom and protected the LE with it.

Even with full poweron dives I have yet to see even a flex out of the wing. It has been rebuilt many times from damage and all of my repairs have still made the integrity of the wing great.

Just my .02
NAES

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RE: TuffFlight Predator X Wing Flutter... - 10/25/2004 6:55:09 PM   
wind junkie



Posts: 1002
Joined: 11/16/2002
From: N. Syracuse, NY, USA
Status: offline 		Thanks for chiming in NAES.

The covering really IS the integrity of the TufFlight planes. One needs to pay attention to getting everything straight, and then the covering will keep things aligned. Tape should be used sparingly, as you have done in critical junctions which attach hard points to soft squshy foam. All this is outlined in the manuals.

It's a tough engineering problem to keep a plane stiff for turns, but soft for impact. The X is on the hairy edge of getting everything done and still coming in under 3.5 lbs for Open B.

When folks use covering other than Ultracote or Icarex, I cringe, cause we've been there, and it's hit or miss trying to predict what will go wrong.

I guess as long one is still having fun, it's fun to experiment. But when contest deadlines come up, all that "fun" experimenting tends to turn to "pressure" when things don't go exactly as planned.

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RE: TuffFlight Predator X Wing Flutter... - 10/27/2004 6:15:43 PM   
NAES



Posts: 64
Joined: 2/27/2004
From: , CA, USA
Status: offline 		I almost exclusively scratch build my own designs. The squishy idea that was pioneered by tufflight has finally caught on by many others after all these years as has the flying wing.

If you follow their directions properly there should be no issues as they have probably seen them all.

I do take many of my idea inspiration from tufflight like the breakaway engine mount, fuel tank/launch handle and removable vertical fins.

My newest batch has leading edges made from boogie board foam or epp. So far they have held up exceptionally well in midairs without destroying the other planes that I have hit.

NAES

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RE: TuffFlight Predator X Wing Flutter... - 10/28/2004 12:52:04 AM   
Clean



Posts: 994
Joined: 4/19/2002
From: Parkville, MO, USA
Status: offline 		I would bet a little carbon fibre mat applied with polyu sanding sealer would probably stop any wing flexing on those long, skinny, flexy wings.

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From Somewhere near Parkville, Mo.
William Crane (aka Mr Clean) Rever Brother #168 Time Man of the Year

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RE: TuffFlight Predator X Wing Flutter... - 10/28/2004 1:53:57 AM   
wind junkie



Posts: 1002
Joined: 11/16/2002
From: N. Syracuse, NY, USA
Status: offline 		Sure it would Clean. Right up until that first impact.

_____________________________

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       Post #: 10

RE: TuffFlight Predator X Wing Flutter... - 10/28/2004 4:40:52 AM   
NAES



Posts: 64
Joined: 2/27/2004
From: , CA, USA
Status: offline 		The problem with CF and a squishy wing is that they are attempting to do 2 different things at the same time. One is trying to go BOING! while the other is going to go KABOOM! on impact.

I have seen composites applied without resin before with OK results. Sorta weird seeing it all movable under the covering though. But I suppose they said the same thing when 3m77 was first suggested as an airplane glue.

NAES

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RE: TuffFlight Predator X Wing Flutter... - 10/28/2004 6:39:26 AM   
wind junkie



Posts: 1002
Joined: 11/16/2002
From: N. Syracuse, NY, USA
Status: offline
quote:

ORIGINAL: NAES

The problem with CF and a squishy wing is that they are attempting to do 2 different things at the same time. One is trying to go BOING! while the other is going to go KABOOM! on impact.

I have seen composites applied without resin before with OK results. Sorta weird seeing it all movable under the covering though. But I suppose they said the same thing when 3m77 was first suggested as an airplane glue.

NAES


Amen to that. It's refreshing to see someone who really understands the benefits (and pitfalls) of each philosophy on how to deal with impact resilience.

In the early R&D phases, I tried a predator covered with kevlar over EPP, and then a layer of white mica-film over that. It was expensive, VERY tough (I have a video of a head on impact -- it folding almost completely in half and then flopping back into shape to glide back for a controlled "normal" landing) but it didn't fly well for very long once the kevlar skin started to let go underneath, and the hinges eventually worked themselves loose.

I actually flew it at the 2001 NATs, but it didn't pan out for various reasons.

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Arguing with an engineer is like wrestling a pig. Everyone gets dirty and the pig likes it.

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RE: TuffFlight Predator X Wing Flutter... - 10/28/2004 1:20:58 PM   
Clean



Posts: 994
Joined: 4/19/2002
From: Parkville, MO, USA
Status: offline 		. One is trying to go BOING! while the other is going to go KABOOM! on impact.


What are you DOING. I got a guy, a new and easy target, heading to the hardware store for some Polyu and you put the breaks on? Mand it coulda been great and you blew it, YOU BLEW IT!!!!

Yea, a little less brittle than CF would be the way I guess. I have seen those long wings flappin before though, not a pretty sight.

I think we should all just go back to flying Gremlins so we could get some good snow.

_____________________________

From Somewhere near Parkville, Mo.
William Crane (aka Mr Clean) Rever Brother #168 Time Man of the Year

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RE: TuffFlight Predator X Wing Flutter... - 10/29/2004 1:56:46 AM   
wind junkie



Posts: 1002
Joined: 11/16/2002
From: N. Syracuse, NY, USA
Status: offline
quote:

ORIGINAL: Clean

I think we should all just go back to flying Gremlins so we could get some good snow.



There are some die-hards that STILL DO fly gremlins. It's a stock class. They fly somewhere near Sturbridge, Mass.

I believe they only fly 2 planes at a time though -- man on man.

_____________________________

Arguing with an engineer is like wrestling a pig. Everyone gets dirty and the pig likes it.

(in reply to Clean)