Minor dilema  
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Minor dilema - 4/28/2008 7:04:53 AM   
Adui


 

Posts: 430
Joined: 8/24/2007
From: Dayton, OR, USA
Status: offline 		So heres the deal. In the minor bump I had before my solo today (See my thread in beginners "I DID IT!!" ) There was some minor wing damage I didn't see till I took the wing off to bring it home. Now the guy i was flying with, who helped me solo agreed with my assessment that no Structural damage was done and the wing is still serviceable. However, I should still fix it.

The wing slid forward in the saddle when she hit, rubber bands flexed allowing it, but the leading edge of the saddle did the damage shown in the pictures I'm uploading.

So should I
1) Tape it for now, its covered by the plane when assembled and the aircraft flies fine without doing anything else.

2) Remove the covering from the affected area and fix the damaged balsa sheeting.

Assuming you tell me 2) which I fully expect (LOL) How do I do this, and do I have to completely recover the wing or can I get away with a patch?


(Keep in mind when answering that I have only just soloed today and fully expect to be a bit hard on this aircraft for a few weeks to come..)

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< Message edited by Adui -- 4/30/2008 8:41:25 PM >

_____________________________

Chance favors the prepared mind. ~Louis Pasteur~
       Post #: 1

RE: Minor dilema - 4/28/2008 11:29:40 AM   
bkdavy



Posts: 1383
Joined: 9/28/2004
From: FrederickMD, USA
Status: offline 		I'd go with option 2. A sheeted balsa wing derives much of its strenght, particularly in the center section, from the balsa sheeting. It makes the structure rigid by preventing flexing of the forward portion of the ribs. The center of the wing is subject to the highest stress. Additionally, there could be damage below the covering that is not visible until you strip off the covering.

Balsa sheeting is easy to repair, and very easy to obtain.

Strip the covering back from the damaged area, giving yourself at least an inch of room. You want to peel it back until you have no damaged section covered.

I assume at this point an inspection of the ribs and the interior wing reveals no damage. If any ribs are found to be cracked, you'll want to repair those cracks before repairing the sheeting. If the spar is cracked or otherwise damaged, that must also be repaired. I'm not going into that repair because its more complex.

Cut the damaged sheeting out on a straight line. Give yourself a large enough hole in the existing sheeting to work.

Make balsa tabs from your new piece of sheeting. These tabs will be glued inside the wing on the edge, and will provide support for the new piece of balsa going into the hole. Glue them in place so they overlap the joint on the inside of the sheeting.

Cut and shape a new piece of sheeting so it fits your hole (this is why square holes are easier to work with). If you need to curve, wet it with Windex or household ammonia and then tape it in place in the hole until it dries. Then glue it in place.

Now fill the gap with your favorite filler material. If you work carefully in the steps previous, the gap should be very small.

Sand the repaired balsa flush with the old surface, then cover the repaired area with matching covering.

Brad

(in reply to Adui)
       Post #: 2

RE: Minor dilema - 4/28/2008 3:30:32 PM   
manks


 

Posts: 195
Joined: 2/26/2004
From: Mississauga, ON, CANADA
Status: offline 		I would agree with the first response, take off the covering and take a good look at the damage. From my experience, there is always a bit more damage then you think once you take a really good hard look.

Take the time, do it right and be sure the plane is airworthy. If you just tape over it, and there is significant damage, you could lose the plane due to structural failure.

Take the extra hour to avoid the extra costs of a major crash. Also make sure you check all of the control surfaces, firewall ect, give the plane a really good check. I had a minor crash, looked like very little damage, when out a few days later, and lost all 4 hinges in my elevator - in flight. I was very lucky to get the plane back on to the ground with out destroying it. Again it will take 10 min, you will likely find nothing wrong, but it is always good to be sure.

(in reply to Adui)
       Post #: 3

RE: Minor dilema - 4/28/2008 5:14:46 PM   
Adui


 

Posts: 430
Joined: 8/24/2007
From: Dayton, OR, USA
Status: offline 		Thats what I figured.. Looks like a visit to Tammies is in order, Im in need of some mo nocote and some Balsa sheeting.

Soo.. which covering is easiest for a first timer to use? Mono cote or Ultra cote??

The balsa Ive a little experience with from the last time this poor ol bird went in. (My first go at the hobby and my stupidity took the firewall off..)

_____________________________

Chance favors the prepared mind. ~Louis Pasteur~

(in reply to manks)
       Post #: 4

RE: Minor dilema - 4/28/2008 5:20:54 PM   
bkdavy



Posts: 1383
Joined: 9/28/2004
From: FrederickMD, USA
Status: offline 		Whatever matches the original coverings color is best. If originally covered with Monkote, you're OK with anything. If its Ultrakote or one of the other lower temperature coverings, Monokote might be hard to get properly shrunk without damaging the underlying covering.

Brad

(in reply to Adui)
       Post #: 5

RE: Minor dilema - 4/28/2008 6:03:10 PM   
fozjared


 

Posts: 543
Joined: 7/1/2007
From: gilmer/nacogdoches, TX, USA
Status: offline 		ultracote is probably easier to use for a beginner imo.

also, this is my opinion only now, but if all the wing did is slide forward and the balsa sheeting is all that is damaged then i would fly it and not waste my time on that because if you just soloed there will be more damage to come. the one thing i would do is to squeeze all of the formers in that area to see if they got crushed, cause that is the structure of the wing, broken sheeting is no big deal, but if that center rib, or the main spar is damaged in any way, that must be repaired! absolutely has to be repaired! just take your hand and squeeze the center of the wing all the way down the center line, squeeze pretty hard to check for cracking etc. then try to pull the wing halves apart and pull hard, if there is any give then i would hesitate to fly the thing.

basically if it feels strong/stable then it probably is strong enough. the only way to be certain that there is no structural damage is to pull the covering and sheeting in that area, but if you are short on time do like i said to test the wing's integrity by hand.

(in reply to bkdavy)
       Post #: 6

RE: Minor dilema - 4/29/2008 11:20:48 AM   
bkdavy



Posts: 1383
Joined: 9/28/2004
From: FrederickMD, USA
Status: offline
quote:

broken sheeting is no big deal


As I said in my first post, this is NOT true. Sheeting is an integral part of the structure of the wing. Although the sheeting may seem weak, when loaded in tension or compression along the axis of the wing, it is essential to the stiffness of the wing.

I was amazed at how important it is when I built my first wing. With just the spar, leading edge, and trailing edge attached to the ribs, the wing would easily twist and bend. Once it was sheeted, it was incredibly stiff. A break in the sheeting like that shown will cause the stresses to concentrate in the undamaged areas, and will likely lead to failure of the wing. A small ding in the sheeting is one thing. The damage shown in the OP could be significant and should be repaired.

And we should never be short on time to repair, and we should never encourage a beginner to fly a plane in that condition. At best we end up with toothpicks. But we would also be encouraging a very bad and unsafe habit.

Brad

(in reply to fozjared)
       Post #: 7

RE: Minor dilema - 4/29/2008 4:23:40 PM   
flyX


 

Posts: 452
Joined: 7/24/2007
From: el centro, CA, USA
Status: offline 		Well...if it was my model.

I cut into the sheeting to inspect the spare. Maybe the crease stopped at the spare..maybe not.
otherwise, i can easily make it look purdy again just by running an iron over the wrinkles[

I wouldn't cut all the way to the ribs.


If the spare was cracked...I have to cut into the sheeting behind spare.
This way i can add doubler in front and rear of the spar. I cut a couple of pieces of scrap ply
or balsa sticks. Epoxy the heck out of it.

If the center ribs are slightly crushed..I try to press it back into place as best I can.
I put a bunch of epoxy on the ribs ..this will stiffen it. And probably the leading edge too.
Actaully it'll just make it stupid hard.lol

After the epoxy cure.

I just add balsa under the orginal sheeting. This is the reason why i didn't cut all the way to the ribs.
This will give a lip for the replacement sheeting to sit on and adhere to.
I cut the new sheeting as close as can to the holes that i made. Sand it flush to the original sheeting.

Then just recover as needed.

The colors arn't going to match..unless you know exactly what the original film is.


< Message edited by flyX -- 4/29/2008 4:36:32 PM >

(in reply to bkdavy)
       Post #: 8

RE: Minor dilema - 4/29/2008 4:34:38 PM   
Adui


 

Posts: 430
Joined: 8/24/2007
From: Dayton, OR, USA
Status: offline
quote:

ORIGINAL: flyX
...

The colors arn't going to match..unless you know exactly what the original film is.


Its built by Hagar 9, and the stats on the new ones confirm its Ultra cote.. (Did some research after posting LOL)

For all the others, Im headed to the hobby shop this week, it wont take but an hour ot two to fix anyhow so Im going to fix it. I am already as certain as is possible without opening it up that the ribs and spar are undamaged, but the sheeting is completely ruined in that spot.

Sooo.. A sheet of balsa (What thickness BTW) some 1 hour epoxy and a roll of Blue ultra cote. and an hour or two of work and she will be good as new. The shame of it is I eventually intend to recover the whole aircraft and change the color scheme to make it more visible, but I cant afford that much ultra cote right now so I either pick the new wing color and patch it with a different color, or go with blue and have a roll I wont use for a long time.

_____________________________

Chance favors the prepared mind. ~Louis Pasteur~

(in reply to flyX)
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RE: Minor dilema - 4/29/2008 4:44:48 PM   
flyX


 

Posts: 452
Joined: 7/24/2007
From: el centro, CA, USA
Status: offline 		If the spare is not crack and you're certain of it. Just run CA or epoxy in the cracks to make it as stiff as possiable.
yeah...i use epoxy as fillers instead of wood filler then just sand it flush.

Why would you need a sheet of balsa if you're not going to cut into the sheeting ?

(in reply to Adui)
       Post #: 10

RE: Minor dilema - 4/29/2008 11:04:22 PM   
Adui


 

Posts: 430
Joined: 8/24/2007
From: Dayton, OR, USA
Status: offline
quote:

ORIGINAL: flyX

If the spare is not crack and you're certain of it. Just run CA or epoxy in the cracks to make it as stiff as possiable.
yeah...i use epoxy as fillers instead of wood filler then just sand it flush.

Why would you need a sheet of balsa if you're not going to cut into the sheeting ?

I understood that I needed to remove the damaged sectiojn of sheeting and replace it with a patch, joining it together with seam overlaps (from the inside) for strength. Im new to this, I have rebuilt the front of my bird but never had to do any wing repair, would just filing the gaps be sufficient? If this is the case why not just tape it and be done since its on the underside of the wing and covered in the saddle...

I intend to fix it right just asking questions to be sure I know what exactly right is.

_____________________________

Chance favors the prepared mind. ~Louis Pasteur~

(in reply to flyX)
       Post #: 11

RE: Minor dilema - 4/29/2008 11:16:50 PM   
flyX


 

Posts: 452
Joined: 7/24/2007
From: el centro, CA, USA
Status: offline 		Becuase..if you just put tape on it..it won't be stiff. That tape will flex.
CA or epoxy will make it hard. Wood filler will just crack and fall apart.

The wing won't mount level. At the very least.

Don't worry. You'll get the hang of it. There's different ways to repair.

The wing is a D design meaning the front sheeted part is shape like a D.
The sheeting keeps the wing from twisting as others had said.

< Message edited by flyX -- 4/29/2008 11:35:08 PM >

(in reply to Adui)
       Post #: 12

RE: Minor dilema - 4/30/2008 12:39:55 AM   
kid chuckles


 

Posts: 680
Joined: 5/2/2007
From: Granbury, TX, USA
Status: offline 		I agree with your going to have a few rough landings most likely with just soloing so just fix what you have to and be done with it. It does not look like much more than wrinkled up a bit. CA or Epoxy and fly the wheels off of it. If it is hidden then you really could just peel the covering back if it does not tear and then reapply it since it does not show anyway. If your planning on recovering it then when you do you can repair it before your new recover job. But also being new it is a hard job recovering a plane and making it look good. Good luck however you go.

(in reply to flyX)
       Post #: 13

RE: Minor dilema - 4/30/2008 2:15:12 AM   
Adui


 

Posts: 430
Joined: 8/24/2007
From: Dayton, OR, USA
Status: offline 		So essentially, I don't need to do surgery and patch it, so long as the spar and the ribs are intact, which I am 99% sure of I could fill the cracked sheeting with epoxy, and then tape the torn covering instead of doing a major surgery on the wing?? Ive got what I need for that right here without a visit to the hobby shop. (Still going, getting my Triton3 charger cycler friday I hope! )

_____________________________

Chance favors the prepared mind. ~Louis Pasteur~

(in reply to kid chuckles)
       Post #: 14

RE: Minor dilema - 4/30/2008 8:30:27 AM