Tinbuzard - One off design

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Tinbuzzard

Retrograde Progress:

I had a rather large setback recently on the Buzzard project. Hangar space is limited, so I had stored the completed right wing underneath our Grumman Yankee. It was up on blocks and wrapped in a tarp, with a drip pan on top of it under a battery drain on the Grumman's belly. Unknown to me, the tarp got pulled off and the pan not repositioned. Murphy was watching, the battery overcharged and puked acid all over the bottom wingskin about mid span. By the time I saw it, the damage was severe with the skin nearly penetrated in two spots. . The acid has gotten into a seam between skins over a spar web and around and onto an access plate. The access plate was installed when the damage occurred, protecting the inside, and removed for the photos. The bottom skin was the first one to be riveted onto the wing, and I didn't think it could be replaced without taking off the top skins as well. I thought when I saw it that I'd lost the whole wing panel.
Acid(S).jpgAcid1(S).jpg
I had to find out the extent of the damage and stop any more corrosion, so I spent a late night drilling out 580+ rivets to remove the skin. I was greatly relieved to find no damage to underlying structure! Corrosion products had gotten under the edge of the skin, but not penetrated the primer on the spar web. I also partially deriveted the leading edge skins from the spar to check underneath. I cleaned everything, including removing the primer to make sure that nothing had attacked the metal beneath. The L.E. skin cleaned up nicely, the spotting looked bad at first, but just wiped off. The 2024-T3 main skin was badly eaten, the 2014 alclad L.E. skin barely touched.
Acid3(S).jpg
Now the good news. The internals are repainted, the new skin from Spruce has been trimmed to shape, match drilled, deburred, and dimpled, and installation has commenced. Luckily, all of the rib and stringer flanges were facing in the only possible direction to allow access for riveting!! I should finish in a few more days, having lost about five weeks on the project. As an added bonus (being optimistic here) this wing was the first one I built and had more goofs on it than the other. Replacing the skin has allowed me to correct a misplaced drain hole, a gap in one of the butt joints, and a wrinkled spot where the rivet gun slipped.
 

Topaz

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Five weeks, ouch. On the other hand, in the whole history of this airplane that's not too bad, and you got to fix some of your learning curve, too. I was jaw-dropped when I first started reading this ("Oh NO!!!!"), but it sounds like it's turning out okay.

You're absolutely sure nothing penetrated into the structure? I'd hate to have a slow corrosion going on, that doesn't make itself felt for several months or longer.
 

austin

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Jun 10, 2011
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This is good design and I am also working on a project. You can say it is similar to this one but I will show the pictures of my work so far.
 

GESchwarz

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Oct 23, 2007
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I'm so sorry to hear about this Tin Man. In this business of homebuilding the answer to most problems is to press on! Discouragement is best defeated with dogged tenacity.

There's a guy in my EAA chapter who was just finishing his Zenith when he learn that the FAA had grounded the Zenith fleet because of the weak wing spar. He had to open both wings and add a retrofit kit. But he got through it and it's now ready to go.
 
T

Tinbuzzard

Update on the damaged wing. Repairs are complete, and the wing primed and painted gray on the bottom. I was very careful to make sure there was no further threat of corrosion. I drilled out and replaced any rivets that might have been affected and removed doublers around the access opening. I wiped down everything with a dilute solution of sodium bicarbonate and saw no reaction. Using the same solution on the removed, damaged skin resulted in strong bubbling and foaming even after I had scraped
off most of the corrosion products.

The first image shows the old and new skins. I shifted the rivet hole pattern on the new skin near the tip 1/2 a hole diameter to remove a slight trailing edge wrinkle in the original. Next is the finished repair. The third shows me halfway through drilling out the leading edge skins over the sparweb to look for damage. Last, a size comparison between the Buzzard and the offending Grumman.
RWRepair1.jpgRWRepair3.jpgRWRepair2.jpgAA1BTB(S).jpg
 

GESchwarz

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Topaz

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Jeff's most-recent post on HBA is that one immediately above from 2011. You'd probably do better with a PM. If he's still using the same e-mail account, he might get it.
 

bmcj

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Jeff's most-recent post on HBA is that one immediately above from 2011. You'd probably do better with a PM. If he's still using the same e-mail account, he might get it.
He also has a SEND EMAIL link attached to his profile.
 
T

Tinbuzzard

Gary, Yes, you can certainly visit. A lot has gone on with my life and project over the last few years. The good news is that I've recently started work on it again after dealing with a problem hangar partner by moving to a new hangar. (same airport, Brackett ) I don't know what information is in my profile: my present e-mail is [email protected] Haven't gotten your e-mail yet; hope to hear from you soon. Jeff
 
T

Tinbuzzard

Long overdue update! Health and family took precedence for awhile. At present, I'm all set up in the new and better equipped hangar and working on my project again.

Recent work has included a major modification to the aft end of the tailbooms and vertical stabilizers. This was one of the earliest parts of the airframe to be completed, and just wasn't up to the standards of later work. I deskinned everything and installed needed doublers between the boom and vertical sparwebs. The original rather sparse rivet pattern was enhanced as well. The verticals were shortened at the bottom, and made three inches wider at the top. This looks a bit better and gives me several inches more ground clearance for rotation. (Oversight of my initial design)

IMG_0021.jpgOriginal inadequate R.H. joint. .040" doubler and #4 rivet pattern.

IMG_6702.JPGRevised right tailboom joint. .063" doublers and #6 rivets into the .090" T boom caps and web. This is a high stress area, so I took care with deburring new holes in older structure.

IMG_6733.JPGNew left vertical skin being fitted and drilled. The bottom will be rounded off after I pinch some foam and glass from the EZ builder at the end of my row.

I've also nearly finished the flap actuation mechanism (torque tube and pushrod) with just the motor mount plate to make. The wing joint access plates are done, as are a couple of small mods inside the wingroots that I put off for a long time because they were hard to access!

Finally, the e-mail addy in the above post is dead. Thanks Frontier! I'm on gmail now: [email protected]
 

Jay Kempf

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Welcome back to the nuthouse! So glad you're back I was going into withdrawals over whether this project was still alive.
 
T

Tinbuzzard

IMG_0005.jpg
Continental IO360 in the engine builder's shop (Performance Aero)

IMG_0007.jpg
Engine mount after welding. This is a hacksaw and file job that took about three weeks to make.

IMG_0008.jpg
Engine being fitted to mount. The structure is designed to withstand a 20+ G impact.

IMG_6505.jpg
Powder-coated mount in the airframe. Oil cooler mounted below and forward of the engine and fed by a belly NACA duct. Battery box holder at the top.

IMG_4657.jpg
Closer view of the oil cooler. The gold tubes to either side are compression members that transmit engine weight to the lower rear wing spar carry-through. Silver tube above the oc is the main gear retract drive.

IMG_4439.jpg
Cockpit left side console. Darker area behind the throttle quadrant is a reinforced step for ease of entry and exit. Tachometer will be in front of the TQ. Forward canopy safety latch not installed yet.

IMG_7171.jpg
Another early deficiency corrected last year. Old (chromated) forward canopy frame above the new one. This gives me 1.5" of badly needed headroom! Turnover structure had to be modified as well--but worth it.

When I look at old photos of this project; all I can conclude is that I was either the most naive builder imaginable back then, or just insane! Here I am in 1981 with the whole project at the time! About half of these parts are still in the present plane.
IMG_0013.jpg
 

cheapracer

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When I look at old photos of this project; all I can conclude is that I was either the most naive builder imaginable back then, or just insane! Here I am in 1981 with the whole project at the time! About half of these parts are still in the present plane.
You are completely normal. Most all the theory, drawings and wordspin fall apart rapidly when it comes to real world building time, as you know well.

You have done very well Sir. :beer:
 

Tinbuzzard

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I'm back again after another building hiatus. First, I got run over during my morning walk and had several bones broken. That was followed by my SO's and another friend's lengthy and ultimately fatal illnesses. I'm fine now, but it took a long time to regain my enthusiasm for projects. Its been thirty-eight years since I began this endeavor, but I'm more confident of finishing it than I've been in a long time.

Recent progress: Ray Allen trim system installed in the HS, lighter less draggy tail bumpers installed, forward canopy latch fabricated (After I figured out how to make it fit), and a remachine of main landing gear parts that removed several pounds of weight!
IMG_9114.JPG
Trim servo package. Custom clevis slides in a delrin block. The servo is mounted in the HS, not the elevator, to position the clevis/rod end joint so it provides a mild antiservo action as the elevator moves. The tab is fairly large, and I wanted to preclude any possible tab flutter.

IMG_9095.JPG
New forward canopy front sliding latch-open. I had positioned the original two hook latches too far aft to adequately secure the canopy, and needed another--but the throttle quadrant was in the way. It was distressing how long it took me to figure out how to do this--it looks so simple finished!

IMG_9096.JPG
Canopy latches closed. I added a small reinforcement to the front corner of the canopy frame. Slider is brass, block 7075-T6.Others think this was a clever way to make room for the quadrant; but I admit it was an after the fact solution to a design oversight!

IMG_9190.JPG
Left main gear original version. Seen through a cc wing access panel. Inadequate die spring, needlessly heavy (Note the blocky half-fork) and didn't retract quite far enough due to a tiny fabrication error in the side link. (.025" difference in one pivot point separation between the right and left gear)

IMG_9162.JPG
Left main from below without gear doors. It hangs down a half-inch more than the right main, and there were interferences inside that wouldn't permit either to move up much more. Retractable landing gear design and fab is a real *****

IMG_9173.JPG
Left main half-retracted. An electric motor drives a jackscrew to pull the links. The hard to machine contoured link just below the green pull arm is of course the one with the fab error! The new ones are 7075-T6 and are lighter and stronger. (and match now)

IMG_9285.JPG
7075-T6 half-fork being remachined on my old Taiwanese mill. I was able to remove 1.2 lbs, from each one without any decrease in needed strength or stiffness! I way over-made them originally.

IMG_9326.JPG
Remade gear struts with 60% higher capacity springs on the oleo strut. They now retract symmetrically 1/2" further into the wells with no interferences! These are designed to withstand a 3G full gross wt. impact on one strut.
 
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