Flight Trimming

User avatar
eta150
Member
Member
Posts: 269
Joined: March 11th, 2009, 3:48 pm
Division: Grad
State: PA
Location: Kville
Has thanked: 0
Been thanked: 0

Re: Flight Trimming

Post by eta150 » February 2nd, 2010, 8:18 am

I believe the Leading Edge is available this year as designed by Cezar Banks. It's available from the A2Z corp store and Turner Toys (in limited quantities).
#ACESWILD

leetx
Member
Member
Posts: 52
Joined: January 22nd, 2010, 5:40 pm
Division: Grad
State: CA
Has thanked: 0
Been thanked: 0

Re: Flight Trimming

Post by leetx » February 9th, 2010, 9:04 am

from last year, jander14indoor wrote:

Yet another (for small changes) is to warp or bend the tail boom using heat (typically your breath).

For large changes you may need to crack and reglue the tail boom. Nice feature, once you get it right, it stays. Bad feature, can add a lot of weight cracking and regluing if you take a lot of changes to get to the right place.
Can you elaborate a little on the "crack and glue"? First, what do you mean by "crack"? I would also like to know the kind of glue you use and how you apply the glue to secure the position after the crack.

I have bent the tail boom using my breath for what I think are fairly large changes, such as resulting in a 5mm + change at the end of the tail boom. I have noticed that over time, the tail boom tends to bend itself back toward the old position, not back to the old position but enough to significantly affect flight.

Thank you.

jander14indoor
Member
Member
Posts: 1585
Joined: April 30th, 2007, 7:54 am
Has thanked: 0
Been thanked: 2 times

Re: Flight Trimming

Post by jander14indoor » February 9th, 2010, 2:28 pm

Yeah, that's the problem with bending with breath, tends not to be permanent.

'crack' is a nice way to say BREAK it, but not too much.

Two approaches, depending on size and hardness of stick.
First, cut about halfway through where you want to crack the stick, then gently flex it at that point, just enough to crack the fibers, but not enough to cause a seperation. Note, you can get complicated bend directions this way by angling your cut if needed. Then apply thin superglue to the crack while holding the stick at the desired position and hit it with accelerator. WIth practice, you can do this on your own, but extra hands can help early on. One cracks and holds the stick in the desired orientation, while the partner applies glue and setter.
To keep from using too much glue, I use a precision micro superglue applicator, two pins stuck through a stick that come together at a point. This lets you pick up small amounts of superglue from a puddle of a drop or two and apply it to a joint, Done carefully, little weight gain. The kink or bend you put in the stick this way is permanent.
Specific example, I want to bend the back of the tail boom around to the left. Cut around halfway through on the right side, perpendicular to the stick. Crack gently till angle is reached. Apply glue to lock.
If you want to bend it up, cut on the bottom.
If you want it left AND up, an angled cut on the right side (or bottom) will do both at once, but you need to figure it out thinking of the cut as a hinge.

Second isn't much different, just skips the cut. Use your fingernails to localize pressure for crack and again, don't overdo it. A little less controlled, but ends stronger as more fibers are continuous across the joint than the half cut.

Hope that's clear, let me know if not.

Jeff Anderson
Livonia, MI

leetx
Member
Member
Posts: 52
Joined: January 22nd, 2010, 5:40 pm
Division: Grad
State: CA
Has thanked: 0
Been thanked: 0

Re: Flight Trimming

Post by leetx » February 9th, 2010, 3:59 pm

jander14indoor wrote:
'crack' is a nice way to say BREAK it, but not too much.

Two approaches, depending on size and hardness of stick. [snipped]
Wow, that is really interesting and not what I expected. I'm glad I asked. I expected you to say to glue inside the cut and to bend to the side of the cut. I think this is because I use acetone-based glue and not CA. I am not experienced with CA, not yet at least. I've read your article on using gglue and will try it out CA. Expect additional questions under the "building technique" topic. :-) Thank you.

calgoddard
Member
Member
Posts: 256
Joined: February 25th, 2007, 9:54 pm
Has thanked: 0
Been thanked: 0

Accelerator for Cyanoacrylate (CA)

Post by calgoddard » February 9th, 2010, 11:30 pm

Sometimes Super Glue (Trademark), otherwise known as cyanoacrylate (CA), will not set up. It may have absorbed too much water over time. The temperature may be too low.

Builders are tempted to use commercial accelerators to get the CA to cure.

May I suggest you look at the Material Data Saftey sheet (MSDS) for the CA accelerator you are considering.

You may decide to use something else. One of my mentors taught me to use household baking soda instead. Just a little sprinkle will usually cause the CA to harden rapdily. Use a small paint brush with stiff bristles to wisk away excess baking soda after the glue joint has set up. Baking soda is totally harmless - heck it is meant for human consunption in cakes, etc.

Of course CA should only be used for quick repairs in Wright Stuff because of the significant weight that can be added. Also, a CA joint is difficult to undo, unless you use a commercial de-bonder, and again, read the MSDS and decide if you really want to use that product.

Remember that CA will bond very poorly to a joint previously bonded with CA. Also CA, particularly the very thin formulations, will only work for a relativley perfect joint, i.e. one that has little or no gap that must be spanned by the adhesive. The tighter the fit between the two wood pieces, the less glue you can use and the stronger the joint will be.

Cezar Banks taught me the bend-but-don't break technique that can be used to advantage by breathing on the tail boom and coaxing it the way you want it to go. Do it over several inches and you will have far less risk of breaking your tail boom. If the tail boom should snap, don't fret, just glue 1/32" sheet gussets about one-half inch long on either side of the tail boom, spanning the fracture. You will gain no more than about .05 grams if you do it properly.

jander14indoor
Member
Member
Posts: 1585
Joined: April 30th, 2007, 7:54 am
Has thanked: 0
Been thanked: 2 times

Re: Flight Trimming

Post by jander14indoor » February 10th, 2010, 6:43 am

Actually, superglue works just fine for WS. Trick is to not use to much.
Search for previous discussion on precision mircro superglue applicator (two pin stuck through a piece of scrap stick, balsa or bass). Or read my glue article on the National SO web page for Wright Stuff http://soinc.org/sites/default/files/up ... weight.pdf
As I say there, used properly, CA adds very little weight over balsa cement. In my experience, the time savings with CA is worth it for younger fliers. Its as easy to hit the 7.0 gm minimum with CA as with balsa cement.

Jeff Anderson
Livonia, MI

User avatar
blue cobra
Exalted Member
Exalted Member
Posts: 417
Joined: April 9th, 2009, 6:10 pm
Division: Grad
State: NY
Has thanked: 0
Been thanked: 0

Re: Flight Trimming

Post by blue cobra » February 10th, 2010, 11:59 am

Right now, my cambered horizontal stabilizer has negative AoA. with a 10cm chord, the LE is about 1/8 inch lower than the TE. I assume 0 or positive AoA would be better, so to get it to fly right with positive incidence on the tail should I move my wing forward? This is all assuming I eventually get gym time this year...
In full color since 2006

User avatar
WrightStuffMonster
Exalted Member
Exalted Member
Posts: 62
Joined: September 14th, 2005, 10:56 pm
Division: Grad
State: AK
Location: the semi frozen arctic
Has thanked: 0
Been thanked: 0

Re: Flight Trimming

Post by WrightStuffMonster » February 10th, 2010, 1:49 pm

blue cobra wrote:Right now, my cambered horizontal stabilizer has negative AoA. with a 10cm chord, the LE is about 1/8 inch lower than the TE. I assume 0 or positive AoA would be better, so to get it to fly right with positive incidence on the tail should I move my wing forward? This is all assuming I eventually get gym time this year...
Nope you are incorrect. A negative AoA in the tail is quite normal and a good thing. Your plane will tend to be alot more stable this way. However, I always trimmed zero in the wing and zero in the tail when I went for maximum times. There was a big danger in doing that though as my plane would drop about 15 feet after every hit.
Image-Alaska
Eagle River High School Class 09
Nationals:
1st Wright Stuff Kansas 07
1st Robot Ramble Washington D.C. 08
Stanford University Class 2013

User avatar
Brucester
Member
Member
Posts: 43
Joined: February 16th, 2010, 9:38 pm
Division: B
State: PA
Location: I wish I was in God's country....Iowa
Has thanked: 0
Been thanked: 0

Re: Flight Trimming

Post by Brucester » February 17th, 2010, 8:30 pm

This is a tad off topic, but since there's no "Flight Log" topic, I wanted to ask a question about flight logs. At the recent Solon tournament I had 7 parameter (now I have 13), but two of those parameters were back wing post and front wing post adjustments relative to premarked lines on the plane that were getting decent flight times. The event director, while checking my flight log, told me a parameter had to be a numerical value and adjustments do not count. I say noting adjustments is one of the most important things you can do in a flight log. He said, "I'll spare you this time, but I'm trying to prepare you for regionals, where they would turn this flight log down because those are not parameters." I didn't argue, but just wanted to know your opinion on the dilemma.

Thanks as always,
Brucester
2011 Nationals:
3rd - Bottle Rockets
7th - Storm the Castle
7th - Towers
22nd - Experimental Design

User avatar
blue cobra
Exalted Member
Exalted Member
Posts: 417
Joined: April 9th, 2009, 6:10 pm
Division: Grad
State: NY
Has thanked: 0
Been thanked: 0

Re: Flight Trimming

Post by blue cobra » February 17th, 2010, 8:56 pm

That 's strange, and I certainly disagree. My flight log had a parameter as "adjustments" including things as vague as "adjust rudder" and wasn't even about the plane I was using and it was still accepted at States. Also AoA is very important. Now, did you just have 'moved up' or 'moved down' or did you take a measurement? If the former then I think even that judge would accept the latter, not to mention having a more useful flight log for yourself.

Not to distract from your question, but as I mentioned my horizontal stabilizer has a LE an eigth inch lower than TE along a 10 cm chord. As I understand, this produces negative lift but provides stability. If I increased AoA to, say, one sixteenth difference, this would potentially provide less negative lift but still have my plane sufficiently stable, eh? This would require me to move my wing forward to maintain my current flight behavior? (if I get any gym time. grrr)
In full color since 2006

Locked

Return to “Wright Stuff B”

Who is online

Users browsing this forum: No registered users and 2 guests