1.20 Yak 54 QB Rebuild after crash
 

My son, Nick White, purchased the 1.20 Yak 54 QB from Aero-Works in the spring of 2008. It was his second R/C model since starting in the hobby. I had also just gotten back in the hobby after a 25 year lay-off.
The Aero-works 1.20 Yak 54 QB is a beatiful model and the quality is great. Nick got the Yak ready in about two weeks and started flying it. It flies as good as it looks and he was very pleased with it. He was so impressed with it he decided to try learning the Basic IMAC pattern with plans to enter the local IMAC contest in Effingham, IL in September. However, during one of his practice flights Nick decided to do some axial rolls on the high rates at a high air speed. The result was a snaped wing tube and a high speed crash into a corn field. The attached pictures show the results. Nick purchased another 1.20 Yak 54 and went on to enter the IMAC contest.
Nick was ready to throw the old Yak away, but I decided that I could rebuild it. The only thing damaged was the fuselage. The wings and tail feathers were in good shape except for a little superglue on some joints and some new covering. I started re-building the Yak in November. Its going to take a while as I don't have a lot of time to spend on it, but I thought I would post pictures and comments in this thread as I re-build the Yak 54.
Your comments and suggestions are welcome.
This first set of pictures are what it looked like after the crash.

Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

WOW, you are a glutton for punishment.[&o] This will be an interesting (re) build thread and I wish you all the luck. I would be very concerned about fuse alignment and ending up with a straight flying airplane. Have you thought of purchasing a new fuse?

RE: 1.20 Yak 54 QB Rebuild after crash
 

these kids, what do they know! before there were ARFs it was obvious that a plane like your's would be much easier to fix than to start over. eyeballit for the alignment and put her in the air and see what happens. looks like fun to me not punishment. enjoy

RE: 1.20 Yak 54 QB Rebuild after crash
 

I am sorry for your mishap. I hate to see a plane hit the deck like that...arrrgh! I do hope you get some enjoyment out of the rebuild, and maybe I will learn a little in the process. I am almost finished with the same build. I am in the process of working through a little "CG" issue, which will be resolved once I have all the pieces and get the OS 1.60 FX installed.

Best of luck!

RE: 1.20 Yak 54 QB Rebuild after crash
 

I know, Grelker, it's going to be a lot of work, but I enjoy the challange of rebuilding. I think I can get it straight as there are several straight sections on this fusealage. I have a couple small work-mates that will hold the front and back sections in place to aid in alignment while the glue dries. You'll see what I mean when I get to that phase.
I asked Aero-works about a new fuselage but they priced one at $200. By the time I bought a new canopy, cowel, etc, I would have the price on a new plane.

Thanks, Capt 1597, I do plan to enjoy this re-build. I'll eyeballit but I will also measure it for being straight. The hardest part is going to be keeping the weight down close to the original weight.


Smacka, I've been reading your posts. My son had an OS 1.20 in this plane. He used a larger radio battery and added about 3 oz of lead to the nose. Had the battery and lead on top the motor mount box. Sounds like your plane had some heavy balsa in the tail end. We plan to put a MLD 28 in ours when its finished. Souldn't have any problems being tail heavy.


Below are some pictures of the nose section after I glued it back together. Sort of like a jig-saw puzzle. The only new pieces are the firewall and the large former at the back of the canopy. I used a lot of triangle stock around the engine mount box and used 1/16" plywood for doublers where parts were broken or cracked badly. I believe it is stronger than original and I have not added very much weight. Luckley the area around the wing tube was not damaged much. The wing pulled the clips and bolts right thru the fuselage sides so I had to add doubles around those holes.

Now that the nose section is rebuilt, I am ready to repair the section behind the canopy. There sure isn't much wood in the section behind the canopy. I only had to buy 2 each 3/32" x 3" balsa sheets and 2 each 1/4 " sq and 2 each 3/16" sq balsa sticks. Total of about $8.00. I'll have pictures of that area in a couple days.

RE: 1.20 Yak 54 QB Rebuild after crash
 

Glad to see that people can still do repair work. You will like the MLD-28 / Aeroworks combo. I may be biased, but it really is a nice combo. The only problem we had was that we had to cut away more cowling that we like. Oh, stay with side exhaust.


Peace,
Steven Chao,
CERMARK,

RE: 1.20 Yak 54 QB Rebuild after crash
 

Hi Ralph!
Nice job on the repair. Boy, I sure would be tempted to start applying layers of varnish to that bird BUT that is why I am the noob...

Give 'em hell...[8D]

RE: 1.20 Yak 54 QB Rebuild after crash
 

Ralph, looks great so far. Can't wait to see step 2!

RE: 1.20 Yak 54 QB Rebuild after crash
 

Thanks for the nice comments guys.

My next step is to get the rear section of the fuselage rebuilt and ready to attach to the nose section. As you can see in the first photo there's a few things missing behind the canopy area. First I have to make a new former from 3/32" plywood. Then I'll removed some of the broken side stringers and balsa sheeting. I bevel cut the four main stringers (that attach to the top and bottom of the balsa side sheeting) so I can splice on the new 1/4" sq balsa stringers that are missing (to be done after the side balsa is replaced).
The ply former is a little tough to make as I only have about 1/2 the old former. As you can see I have my son's new fuselage so I can take measurements and see how pieces go together. I measured the height and width of the former in the new fuselage so I can get the former for the rebuilt fuselage the correct size. As you can see in the 4th and 5th pictures it came out looking real good. It is now superglued in place. In the 3rd picture I had to see if it looked anything like the new fuselage. It appears there is some hope !!
The next step will be to splice on the balsa fuselage sides from the new former to a little past the former at the rear of the canopy. I am lucky that the 1/16 sheet balsa at the front part of the turtle deck is in good shape as it makes it a lot easier to get the spacing correct on the formers and the correct length of the fuselage. When doing a rebuild like this you never want to remove any broken parts until necessary as they help align things.
I'll be back when the sheet balsa side extensions are glued in place.
Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

If you are flying 2.4 GHz, now is a great time to remove the antenna tube and have a ritual burn :)

RE: 1.20 Yak 54 QB Rebuild after crash
 

I'm back. This step is gluing new 3/32" sheet balsa sides on the fuselage between the formers behind the canopy area (the area the sides are missing). As you can see in picture 1, I have cut the old balsa sides off at an angle top and bottom and cut the four 1/4" square main side stringers at an angle also. The new 3/32" sheet balsa was cut to the correct width of 2 9/16". Then I cut the angles in the rearward end to match the angles I had cut earlier in picture 1. Also I cut out the notches for the tabs on the former. Then the sides were epoxyed on being careful to make sure they are straight with the original sheet balsa sides. I added a small piece of 3/32" balsa (about 1/2" x 1 1/2" ) on the inside of each splice in the sheet sides for strength. Pictures 2, 3, and 4 show the results.
Now I am ready to clamp the tail section onto the nose section. Once I have the total fuselage lined up straight I will cut the sheet balsa sides just ahead of the former at the rear end of the canopy.
I'll show this step in my next post.
Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

Hello, I am now ready to clamp the two sections of the fuselage together so that I can cut the splice angles in the 3/32" balsa sides. I used four C-clamps to hold the sections together. Note: The 1/4" square balsa stringers are not glued on the 3/32" balsa sides at this point as they would be in the way for clamping the balsa sides together . I clamped them together and then measured and eyeballed the fuselage for being straight (up-down, side-side and twist). As you can see, I used scrap plywood to protect the balsa sides from the clamps. It took about 4 trys to get the fuselage straight. I used the CF wing tube and stab tube to check for any twist in the fuselage. Also, I used a good quality 4' level as a straight edge. Once it was straight I marked it with blue tape so it would be easier to line up if I had to take the sections apart.
Once I had the sectons clamped together straight I was ready to cut the angle splice in the 3/32" balsa sides. Using a new x-acto blade and metal straight ruler I cut through the top 3/32" balsa side and about 1/2 way through the bottom 3/32" balsa side. I was very careful not to cut into or score the 1/16" plywood doubler beneath the 3/32" balsa side. That would greatly reduce the strength of the fuselage if the 1/16" plywood was scored or cut into.
Once the angle splice cut was made I unclamped the two sections of the fuselage. I then removed the 3/32" balsa side in the area where the new balsa side was to be glued to. Again being very careful not to cut into the 1/16" plywood doubler. The results of the angle splice cuts can be seen in the final two pictures.
The next step is to glue the two sections of the fuselage together. I'll show this process in the next post.
Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

Was kinda wondering why the wing tube would break doing rolls?

RE: 1.20 Yak 54 QB Rebuild after crash
 

Hi Hanko, We were surprised too. I wasn't there when it happened but Nick described it to me. He said he was on high rate on the control surfaces and going at a high air speed (probably full throttle). He decided to do several full rate aileron turns. He had done it before when I was there and the wings become a blur at the high rate control throw. Anyway, he said the plane started to arc downward so he stopped the aileron turns and pulled up elevator to level out. Sounded like a shot gun went off according to Nick. It completely sheared off one side of the tube and cracked the other side. The plane decended into a grown corn field with the one wing off. He called me and I came to help him look for the plane. Happen just a few feet in front of him but it took us about 2 hours to find the plane in the corn field (after dark). The battery status light was what I saw first in the dark cornfield. The results of the crash can be seen in the first pictures of this thread.
Aero-works told my son it was the first wing-tube failure they knew of on the .90 - 1.20 yak QB.
Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

I think the plane will recover from the crash quicker than Nick! He's still traumatized from seeing the plane go down. I think whenever you have something fail and crash or you accidentally put one in with a dumbthumb it sticks with you for a while. That's why I flew foamies for so long - Ralph must have watched me crash at least a 1/2 dozen times. You crash enough, try to learn from it, and it will beat out any sensitivities you have about your plane.

RE: 1.20 Yak 54 QB Rebuild after crash
 

Well, it's time to epoxy the rear section of the fuselage onto the front section.
I planned to use 1 hour epoxy to give me plenty of working time to align the two sections. However, I could not find any store or hobby shop that carried 1 hour epoxy. I had to settle for 30 minute epoxy. Since my basement was only about 55 degrees I figured I would have a little more than 30 minutes to work with it.
Not really much to it as far as glueing the sections together. I did a couple of practice runs and discovered it was easier to stand the fuselage on its nose rather than laying it on a table. As you can see in the pictures, I used small c-clamps, clothes pins and some blue tape to hold the sections together while the glue set. I also temporary clamped a couple of 1/4" square balsa strips to the bottom side of the 3/32" balsa sides to keep them from flexing to much.
With my son Nick's help, we applied the epoxy and clamped the sections together as straight as possible and then measured for straightness and twist. It was a little off so we loosened the clamps adjusted the alignment and re-tightened the clamps. Had to do this 2 times before we got it straight. It was a good thing the temp was only 55 as it seemed like the epoxy started setting up a little sooner than I would have prefered. But we did get it together and aligned before it started setting up.
The last pictures show the fuselage after the clamps and tape were removed. It came out perfectly straight. It finally looks like a model airplane fuselage again. Now I have to repair the turtle deck sheeting and install the 1/4" sq and 3/16" x 1/4" stringers on the bottom and the fuselage will be ready to prepare for covering.
I'll post pictures of those steps next time.
Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

Hello again, The first two pictures show the 1/4" sq balsa strips that go along the top and bottom of the 3/32" balsa sides. They really added a lot to the stiffness of the fuselage.

The 3rd picture is of the damage to the turtle deck. I cut the damaged area out to the former on the back side and parallel to the grain across the top side. Then the new 3/32" balsa decking was CA glued into place. I have decided not to cut out the balsa opening in the sides between the formers behind the canopy. I figure it helps a little on strength and since I'm planning on using a MLD 28 gas engine I'm not worried about being tail heavy.

The last 2 pictures show the 3/32" balsa doubler I glued to the inside of the angle splices on the balsa sides where I joined the front and rear sections of the fuselage.

All that is left is to add the 3/16" x 1/4" balsa stringers on the bottom of the fuselage. I picked out some fairly hard balsa strips for this. I'll post pictures of those next time. Once the stringers are done the fuselage will be ready to prepare for covering.
Until next time,
Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

Well I have installed the 3/16" x 1/4" stringers along the bottom of the fuselage. I was going to splice in just the missing section of the stringers but discovered it was going to take just as many sticks of 3/16" x 1/4" as it would to replace the full length of the stringers. So I removed all the bottom stringers and installed new ones.
With the bottom stringers installed the fuselage is completely rebuilt. I have sanded the fuselage with 100 grit sandpaper to prepare for covering. I'll sand it with 220 grit before I apply the Ultracoat. I am very please with the final results of the fuselage. It is straight and a little stronger then when new and I don't believe any heavier.
Now I am going to remove the covering from the wings and stab to check for any damage. I already discovered a mouse took up residency in the wing while it was in the garage. Chewed a little on the balsa but not enough to hurt. I am not going to cover the fuselage until I get the wings and stab ready to cover because I want to take a picture of the completed framework of the entire plane assembled. Also I want to get weights of the parts before covering. Right now the fuselage weights 830 gm (1 lb 13 oz) without the canopy, cowling, landing gear or engine mount.
I'll post again when I see what, if any, damage there is to the wing and stab. Starting to think about getting the engine (MLD 28) and servos (Hobbico).
Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

Great job, what kind of covering ideas you got? Also, just curious what kind of tools you use to cut your wood for the repair? Band Saw?

RE: 1.20 Yak 54 QB Rebuild after crash
 

If you can put the covering on in the original scheme, strip everything out of his other plane and then ask your son to choose between just the 2 fuselages....I think he would have a hard time to tell them apart.
That is very nice work.

RE: 1.20 Yak 54 QB Rebuild after crash
 

Man that is amazing! NICE work. Ive never seen somebody rebuild a fuse like that. Very NICE!!!

RE: 1.20 Yak 54 QB Rebuild after crash
 

:D Great job! I used to know some modellers that prided themselves on being able to repair almost anything. Your work is right there with theirs. I never had the heart to do such extensive work myself. My hat is off to you for saving the plane.

RE: 1.20 Yak 54 QB Rebuild after crash
 

Ralph,

That is some great work. I followed the thread from the first post and I was amazed how you rebulit the fuse and how striaght it is. Looking forward to seeing the fuse being recoved.

Regards,
Chuck

RE: 1.20 Yak 54 QB Rebuild after crash
 

I got all the ultracoat covering off the wings and stab. Ultracoat comes off a lot easier than monocoat does.
The stab and elevators are in perfect shape. All I have to do to them is re-cover.
The wing that came off the yak in the air also is in perfect shape. I'm going to just superglue a few joints and repair the ribs the mouse chewed on and it will be ready to cover.
The wing that stayed on the aircraft and went down with the crash is also in very good shape. The main damage was on the trailing edge of the wing. Where four of the ribs attach to the TE the bottom sheeting is barely cracked. Two of the shear ribs on the spars near the servo mount where also cracked and loose. One of the spars (spruce) also has a small splinter in it near the servo mount area. I'll show my repairs in these areas on the next post.
I weighed the fuselage, wings and stab/elevators with no covering. Fuselage w/o canopy or cowling, with rudder 830 gm or 1 lb 13 oz. Wings with ailerons (no control horns) are 332 gms or 11.7 oz each. Stab/elevators with control horns are 73 gm or 2.6 oz each. The stab/elevators weighed 91 gm or 3.1 oz before removing the ultracoat.
I had to see how the plane looks all asembled. Below are the pictures.
Ralph White, Neoga, IL

RE: 1.20 Yak 54 QB Rebuild after crash
 

Your skills are amazing. I would never be able to do that. Very nice!