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From Avistar Rescue to Avistar Ressurection!

#1
As some of you may have read in the Not Quite Flight forum, my Avistar had a rather violent unplanned landing when the elevator control horn failed... At first I thought it was a radio glitch, but I was able to cut the throttle, so that kind of ruled out radio glitch. The horn failed during a stall turn. Exiting the turn, I initially had some up elevator and then had nothing at all...

When I first walked up to the crash site, I was not confident that the fuselage was even going to be repairable. I didn't have a camera with me, so there are no "scene of the incident" pictures. I was also quite worried that my old OS FP40 was going to be ruined. I have since cleaned it up, and it seems to have suffered no ill effects besides the broken propeller. I have yet to run it, but the crank does not appear to be bent and there is no binding.

Here's the damage, without the shattered bits of the right side of the fuselage in the picture:


I made multiple trips to the crash site to try to find all the little bits. It took a while of walking concentric circles around the crater before I found the windscreen and the front wing mounting dowel. I spent quite a few hours that night trial fitting shattered bits of balsa and ply together. After a while, I decided that it might actually be possible to piece the fuselage back together. Here is the sort of reassembled right side laying next to the fuselage. At this point there are still few bits of framework not reattached. You can also see that the firewall is missing a corner. Unfortunately, I was not able to find all the bits of the firewall. The multiple pieces of the bulkhead that supports the rear of the fuel tank have been glued back together at this point, and the wing mounting dowel is glued also back in place.


Here is the side during a trial fit. It doesn't look too bad at all! This is the point where I decided that it was genuinely salvageable. It was also at this point that I realized I needed to make a new firewall...


Fortunately, I had some 1/4 inch ply in the garage, left over from one of my wife's projects. I was able to make a close enough simile, using the old firewall as a template, that fit quite well. It is not the greatest quality plywood in the world, but a thorough soaking with thin CA really made it stiff. I was a little hesitant to use it, but it is what I had on hand. With no LHS, hobby grade ply is hard to come by... Here it is in the plane. At this point, the side is glued back on and the fuel tank is mocked up to check clearances.


The crash caused some damage to the tail as well, so stripped the covering from the horizontal stabilizer and got it glued back together.


Since the tail has now been broken at every rib, I am also going to make some corner gussets to reinforce the leading edge.

Based on the damage to the front of the fuselage, I knew I needed to strip the rest of the fuse and check for any damage that was not obvious with the covering in place.



Notice how far back this crack runs:


And these cracks on this side:


It was also broken behind the wing saddle:


Thin CA is a wonderful thing for wicking into all the cracks and open joints in balsa and ply! I still need to add some stiffening in a place or two, and will likely glass a few areas, but overall I think the fuse is in good shape now. There was also some damage from the vertical stabilizer popping out in the crash, but mostly just cracks that were easily sealed with thin CA.


At this point, it seems that I have added minimal weight with the repairs. I will have some repairs to do on the wing as well. It has some damage in the region where it meets the fuselage and one shattered rib. The mounting region I will glass, to regain strength, and I think I have all the pieces of the rib. The fuselage will need some filler and some balsa grafts in a place or two, but I am really pleased with how it is coming back together.

With the fuse as torn up as it was, I really didn't want to patch the covering, so it's getting a full re-cover. I have ordered some colors that I think will go quite nicely together, and are also the colors of my alma mater.

More to come as I progress. I am going get the wing stripped in the next couple of days and will hopefully be to a point where I can start the covering by next week.
 

Ak Flyer

Fly the wings off
Mentor
#2
Looks good man, I know what it is to rebuild a trashed balsa model. I finished my fuselage and covered it but the wing is still on the shelf waiting for me to finish it. I need to get a new engine and get my motivation back. Your build pics are helping though.
 
#3
A quick update, and I'll try to get pictures up in the next day or two. The wing is stripped of covering and control surfaces. The shattered rib is repaired and I added CA to all of the rib/spar connections. There is a noticeable difference in the rigidity of the whole wing structure with the added CA. The crash also dislodged the CA hinges on the right side of the wing, so I will be replacing all the hinges with Dubro pin hinges. I actually think the CA hinges contributed to the failure of the elevator control horn. At the extreme ends of the throws, the CA hinges offered a fair bit of resistance. With the control surfaces stripped and removed, I will refine and re-hinge all the surfaces.

There were a couple areas where the covering had some gaps and the wood got fuel soaked. I currently have all the fuel soaked areas covered in K2r spot remover. I will reapply the K2r for the next few nights. With any luck I will have it ready for covering in a week or so. I am probably going to have to paint the previously fuel soaked areas with Balsarite in order to get good adhesion. Even with the K2r, it's not likely I will get all of the oil out of the wood.

I still need to get the light weight spackle on the fuse and a spot or two on the wings.

It's all taking a lot more time than I had originally anticipated. I had really hoped to have it back in the air by now. At this point, I'd rather take a little more time and make sure it's right, rather than rushing through it and being disappointed with the results. I really hope to get it to a point where it's not really even noticeable that it was crashed.
 
#4
Being the possessor of one of the crappiest cameras around, I apologize in advance for the absolutely terribly color in these pictures. The covering is actually Cub yellow. I have the covering on the bottom of the wing. I think, for the first balsa wing I have covered in many years, that it came out quite good. I will likely do the top tomorrow. The top will be a mix of black and yellow and I am not quite sure how to achieve the scheme I want. I don't think I want to overlay the whole portion I want black, I am afraid I will get too many air bubbles. I think I will put the black down first and then do the yellow. My concern is keeping the lines straight. I intend to use some silver pin stripe tape to separate the colors, so hopefully that will cover any variations in the straightness of my covering seam....





It's hard to tell from the pictures, but the surface is wrinkle free! The covering is TowerKote and it seems to behave very much like EconoKote. I have to say, from the patch jobs I have done, the Econo/TowerKote is much easier to work with than MonoKote. I have a much easier time getting the wrinkles out of the TowerKote. It is a bit more forgiving than the MonoKote.
 
#5
Some More Progress

I have made some progress on the Avistar rebuild. The whole wing, with the exception of the ailerons, is now covered. This is the first full balsa wing I have covered, so it's decent 10' covering job, but certainly not without some issues. It's also the first two tone that I have done, that wasn't just an odd colored patch so I can keep the plane in the air.



The wing tips have plastic caps that I will be painting black, and attaching, so the covering on the ends is not critical. Based on the amount of fuel soaked balsa I had to deal with, I was really focused on making it fuel tight.





I am going to use some automotive pin striping to delineate between the black and the yellow. At this point, I am thinking silver or red.

The bottom of the wing.



The fuselage is coming along slowly. I have it filled and sanded. I need to decide if I have going to keep the factory control rods or if I will go with some Golden Rods I have for another build.



The fuselage will be black on the nose, and yellow on the top. I am going to use the black for the windows as well. I am going to curve the covering along the bottom, and up across the nose just in front of the hatch above the fuel tank. Here is my scanned artist rendition;) I know I didn't use any of the schemes for the wing I sketched out, but it's close enough. For my first two tone job, it was tricky enough. Please excuse the crude sketching of the drawing, I was just trying to get an idea of how it would look. I have to plan this sort of thing out. For the fuselage covering I am going to seam and tack on the covering with it on a piece of glass. I ordered a 24x36" piece of plate glass yesterday to use for covering work. It worked okay doing it on the wing, but the tutorials I have watched make it look quite a bit easier to do on the glass. The pin strip between the colors will also hide a few sins.



This will be good practice for the other builds I have planned for the upcoming winter. I have a SIG Kadet MkII to finish for my dad, a Senior Telemaster for myself, and likely an Herr Cloud Ranger. The SIG I might convert to electric so it's more convenient for my dad, but the Cloud Ranger is going to get an OS .10 and the Telemaster will probably end up with a gas engine on it.
 
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#6
That looks like it's coming together great. Because I wanted to see what it would look like (and because I apparently don't have enough to do at the moment) I knocked the fuse and pinstriping colors together in Gimp. Here are the results.

The silver pinstriping;
silver test.jpg

The red pinstriping
red test.jpg

The red I picked out is too bright, but it gets the idea across.
 
#7
That's awesome!!!! The silver is more subtle, but I do really like the red! I just happen to have a red spinner for it, so red may be the choice! Thanks for doing that, that's really cool!
 
#8
Another small update. I now have all the surfaces ready for covering. One mod I did to the horizontal stabilizer is the addition of a finished end. The Avistar originally came with plastic caps on the wing tips, vertical stabilizer, and ends of the horizontal stabilizer. When the plane was given to me the caps for the horizontal were gone. I didn't really care too much and was planning on doing something with it when I re-covered it. Since my unplanned landing hastened the re-cover job I also built up some balsa tips for the horizontal stabilizer.







I cut the top of the vertical off, so it was flush with the top of the rudder. This was easier than making a cap. Also, the vertical is 1/4" rather than 3/8" like the horizontal, so it would be pretty fragile if I made something similar to the horizontal.



Fuel soaked wood has been a real challenge. the bottom rear of the vertical stab was soaked and it took more than half a day to get the oil out. After 4-5 hours in rubbing alcohol I was able to take a paper towel and my covering iron to get the rest out.

Slow progress, but progress nonetheless....
 
#11
The covering is almost complete!! Just the ailerons and the elevator to cover!! I was in this hobby many years ago and then we always had a friend cover our planes for us. I have to say, it's not that easy!! Besides a HZ Super Cub, this is the first full plane I have covered. The transitions are the killer part. I am not good at the transitions. A two tone might not have been the best choice, but I definitely learned some things. The Tower Kote seems to be just like Econokote and it goes on pretty well. Where it really looks bad is the transitions from one color to the other, like the leading edge of the wing and the horizontal stabilizer. I would call it a good 10 ft covering job, i.e. it looks pretty good from 10 feet away. The black was bit trickier to work with than the yellow as well. I had a couple spots where I melted the black and the adjacent yellow had no ill effects...













And yes, the surface of the covering is only as good as what is underneath. In spite of my time sanding, there's still a few areas that are a little bumpy. My builds this winter, I am going to build with wood glue and not CA. The wood glue will actually sand, the CA is so much harder than the balsa, it's difficult to get a good surface.
 

xuzme720

Dedicated foam bender
Mentor
#13
I do too! And don't sweat the picky details too much, can't tell in the pics. if you really can't live with it, build some more balsa planes and get some more covering application practice! :)
 
#14
This one was really intended to be practice for some winter builds. I already have a short kit for a Senior Telemaster, a SIG Kadet Mk II, and some other plans that will be used to build some balsa planes. This Avistar rebuild has been excellent practice.

I know it's silly, but I plane my builds around what engines I have... I currently have an Enya .40 for the Kadet, an OS .10 for one of the other plans and oddly enough, I don't have an engine for the Telemaster, but I am leaning towards a 20cc Evolution small block. I also have some plans for some .049 planes since I have a TeeDee .049 in a box as well.

All in all, I am pretty happy with the Avistar. It looks a LOT better than it did when I got it. The old covering was turning yellow and had so many patches, it was starting to look like a patch work quilt. This is a plane that I just want to fly and have fun with, so I am completely okay with a 10 ft covering job. it's exactly what it needs. I am just getting anxious to get it back in the air! I have been missing the smell of the nitro and the sound as well. Luckily, there were a few nitro planes at the field this morning, so I got my nitro/castor oil fix;) Hopefully by next weekend I'll have this back in the air.
 

xuzme720

Dedicated foam bender
Mentor
#15
I pulled my .40 size trainer out of the shop and brought it inside for some going over. The covering is still in great shape once I got all the accumulated dust off. I pulled out the Rx and battery pack (nicads to give you an idea of the hangared time), the fuel tank (I expected a gunky mess, but I guess I did pretty good draining it after the last run. Pretty much zero residue and even the tubing seems in decent shape.) Trying to decide on keeping it glow or making it electric. Either way, I'm going to put it back in the air relatively soon.
 
#16
I pulled my .40 size trainer out of the shop and brought it inside for some going over. The covering is still in great shape once I got all the accumulated dust off. I pulled out the Rx and battery pack (nicads to give you an idea of the hangared time), the fuel tank (I expected a gunky mess, but I guess I did pretty good draining it after the last run. Pretty much zero residue and even the tubing seems in decent shape.) Trying to decide on keeping it glow or making it electric. Either way, I'm going to put it back in the air relatively soon.
Electric is convenient and clean, but I REALLY like the sounds and smell of glow!! It's what I started the hobby with. 30 years ago, electric was terrible, so glow was really the only option. I'll wipe a little goo off of a plane just to have the sounds and smells of glow.

The Avistar, being a step above a basic trainer, is quite a bit of fun! With the semi-symmetrical airfoil and lower dihedral, it can do more aerobatics than I know how to do. I am excited to get it back in the air. The Kadet and Telemaster are just for fun. The Kadet is actually for my dad, and the Telemaster is going to be a glider/banner tug, and just an all around slow floaty flier.
 
#17
Ready for Maiden Flight

It's finally ready for a maiden flight!! Being the first balsa plane besides a stick and tissue rubber band plane, I learned a lot with this rebuild. The glue in the front, from the extensive rebuild, makes it just a tiny bit nose heavy. I think I can probably slide my batteries back and get dead on, but I am okay with just a little bit nose heavy for a maiden.



















 
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#20
Thanks guys! From 10 ft away, or in a picture, it looks really good. My covering job wasn't perfect. I learned a lot covering this plane, so hopefully subsequent covering jobs will be much better.

I really like balsa planes. It's just a matter of opinion, but I think balsa flies a little better. I like my foam planes, but I really do like balsa. There's just something about a plane that didn't come out of an injection molding machine. I know the Avistar started life as an ARF, but now with the rebuild, it definitely has personality all its own.

I have a lot of balsa builds planned this winter. On the docket is a Senior Telemaster from the RCM plans (I already have a laser cut short kit). I have a SIG Kadet MkII to finish for my dad; the Kadet was started in about 1980 or so, and only the wing halves are built. I am also about to pull the trigger on an Herr Cloud Ranger. I also have plans for a 48" wing span "built from plans" DHC2 Beaver.

EDIT: As far as a name, I was thinking Lazarus. Not that I possess any divine power, but it is definitely back from the dead. With regard to Phoenix, it's not bad, but it's also what everyone would be expecting.
 
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