Tinbuzard - One off design

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lr27

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Nov 3, 2007
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3,822
TB: You are an amazingly persistent fellow. I hope you'll be able to finish this without any further major obstacles. Very impressive. A side benefit is that, even if you visit an enormous airport, you won't have any trouble finding your plane. ;-)
 

jedi

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Aug 8, 2009
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2,801
Location
Sahuarita Arizona, Renton Washington, USA
Anyone know the location of this project. There is a very similar one at KAWO north of Seattle but it does not appear to be the same project. I've only seen the KAWO project twice and do not know much about the build but it has similar planform and build time characteristics.
 

cluttonfred

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So great to see you back at this project despite all the challenges, technical and personal. I am really looking forward to see this one fly! Rooting for you.
 

plncraze

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May 11, 2006
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No more jogging! It's bad for your health. You're safer in your BD. Betcha you don't hear that very often! Seriously, welcome back!
 

karmarepair

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Anyone know the location of this project. There is a very similar one at KAWO north of Seattle but it does not appear to be the same project. I've only seen the KAWO project twice and do not know much about the build but it has similar planform and build time characteristics.
Southern California, according to his sig/avatar.
 

Tinbuzzard

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Feb 15, 2020
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Southern California
It's good to be back! Here are a few more images that show internal construction details. Later this spring, when I finish the gear mods and paint the tail section, I will assemble the whole airplane and roll it outside for more pics. (Wings and all control surfaces are completely done, painted, and ready to fly) This will be the first time I've done that in several years. I need to see that for my own incentive!

We'll start at the nose and work back.

IMG_9111.JPG
Nose gear mounting viewed up and aft through the well. (It retracts forward) The original NG circa 1985, was structurally fine, but had inadequate steering travel and the wrong contact geometry with the ground. I hadn't bought Pazmany's LG design book yet. This second assembly corrects all those issues, but looks complex as I had to adapt it to existing structure! It has a direct connection to the rudder pedals and plenty of steering travel now. It is designed to center itself as it retracts regardless of the position of the pedals! The red anodized piece tops a shaft and spring cartridge that connects to and rotates the wheel fork; the stainless fork and brass slider block above it accommodate not only steering and retraction, but moves vertically for shock absorption. Gear door on left closes mechanically. This assembly was certainly the most difficult single thing I designed on this airplane!! It was incredibly gratifying to hook it up to a battery, flip the switch and see it operate correctly the first time.

IMG_9192.JPG
Nose gear and door showing uplock bolt on half-fork. On upper right is the retractable step for pilot and passenger ingress and egress (I'm ex-NASA ok?) It extends when you open the front canopy and retracts when you close it.

IMG_9193.JPG Step with reinforcement plate and no-slip surface. Right maingear behind. Passenger puts left foot on right side of step--right foot up on wing--and climbs in. Pilot places right foot on left side of step and swings his other leg over the cockpit sill where there is a step inside. (Photo of that somewhere above) Step can easily hold 350 lbs.

IMG_0008.jpg Step mechanism with internal pivot point support ribs and sector gear driven overcenter locking links. (Geometry in photo inaccurate) Bushing on step bracket pivot, roller bearings on link pivots.

IMG_9036.JPG
Rear face of center section main wingspar, left side. Red tube and bellcrank are for the left rudder. Heavy block at top is the compression side of the spar, with a rod end just visible for attaching the outer wing panel. Web and cap for the tailboom come in from the upper right and attach to the spar block. The aft pull force from the tailboom spar counteracts a forward force imparted to this area by the aft swept outer wing spar. Center section spar caps are straight across. Spar web and doubler are .187" thick here as a lot of forces converge at this point. Bottom left are the 4340 fittings and pin that attach the tension side of the spar. Fittings and bolts here will hold 80,000 lbs. (6G load at gross wt.)

IMG_9089.JPG
Center of center section from below, looking aft. Elevator pushrod from control sticks in center, connected to an adjustable motion amplifier assembly that rotates the torque tubes to either side. (Redundant controls down both tailbooms) Red plates projecting forwards are for bobweights to tailor stick forces if needed. The flap retract torque tubes (Not installed here) also fit here, right above the top of the picture.

IMG_9033.JPG The outer end of the left elevator torque tube at the end of the center section. The pushrod down the tailboom is hidden behind its upper sparcap strips at the top of the image. The larger clearance tube around the various torque tubes allows them to penetrate the 60 gallon wet wing fuel tank on each side.

I'll post more later!
 

Erik Snyman

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Joined
Oct 9, 2019
Messages
111
It's good to be back! Here are a few more images that show internal construction details. Later this spring, when I finish the gear mods and paint the tail section, I will assemble the whole airplane and roll it outside for more pics. (Wings and all control surfaces are completely done, painted, and ready to fly) This will be the first time I've done that in several years. I need to see that for my own incentive!

We'll start at the nose and work back.

View attachment 93443
Nose gear mounting viewed up and aft through the well. (It retracts forward) The original NG circa 1985, was structurally fine, but had inadequate steering travel and the wrong contact geometry with the ground. I hadn't bought Pazmany's LG design book yet. This second assembly corrects all those issues, but looks complex as I had to adapt it to existing structure! It has a direct connection to the rudder pedals and plenty of steering travel now. It is designed to center itself as it retracts regardless of the position of the pedals! The red anodized piece tops a shaft and spring cartridge that connects to and rotates the wheel fork; the stainless fork and brass slider block above it accommodate not only steering and retraction, but moves vertically for shock absorption. Gear door on left closes mechanically. This assembly was certainly the most difficult single thing I designed on this airplane!! It was incredibly gratifying to hook it up to a battery, flip the switch and see it operate correctly the first time.

View attachment 93448
Nose gear and door showing uplock bolt on half-fork. On upper right is the retractable step for pilot and passenger ingress and egress (I'm ex-NASA ok?) It extends when you open the front canopy and retracts when you close it.

View attachment 93449 Step with reinforcement plate and no-slip surface. Right maingear behind. Passenger puts left foot on right side of step--right foot up on wing--and climbs in. Pilot places right foot on left side of step and swings his other leg over the cockpit sill where there is a step inside. (Photo of that somewhere above) Step can easily hold 350 lbs.

View attachment 93450 Step mechanism with internal pivot point support ribs and sector gear driven overcenter locking links. (Geometry in photo inaccurate) Bushing on step bracket pivot, roller bearings on link pivots.

View attachment 93451
Rear face of center section main wingspar, left side. Red tube and bellcrank are for the left rudder. Heavy block at top is the compression side of the spar, with a rod end just visible for attaching the outer wing panel. Web and cap for the tailboom come in from the upper right and attach to the spar block. The aft pull force from the tailboom spar counteracts a forward force imparted to this area by the aft swept outer wing spar. Center section spar caps are straight across. Spar web and doubler are .187" thick here as a lot of forces converge at this point. Bottom left are the 4340 fittings and pin that attach the tension side of the spar. Fittings and bolts here will hold 80,000 lbs. (6G load at gross wt.)

View attachment 93452
Center of center section from below, looking aft. Elevator pushrod from control sticks in center, connected to an adjustable motion amplifier assembly that rotates the torque tubes to either side. (Redundant controls down both tailbooms) Red plates projecting forwards are for bobweights to tailor stick forces if needed. The flap retract torque tubes (Not installed here) also fit here, right above the top of the picture.

View attachment 93458 The outer end of the left elevator torque tube at the end of the center section. The pushrod down the tailboom is hidden behind its upper sparcap strips at the top of the image. The larger clearance tube around the various torque tubes allows them to penetrate the 60 gallon wet wing fuel tank on each side.

I'll post more later!
Tinbuzzard,
Beautiful work, mate. Now, may I be so bold as to ask that, when you finish the plane, will you build me one?
.....wait, I`m 56 now, plus 40 years building time....no, don`t worry.... :>)
Erik in Oz.
 

rivilee

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Jul 22, 2014
Messages
67
Location
Tullahoma, Tennessee
I'm really curious to see more pictures! For some reason I can't get the pictures you posted ~17 years ago to open....
 

Victor Bravo

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Joined
Jul 30, 2014
Messages
9,843
Location
KWHP, Los Angeles CA, USA
Wow Tin Buzzard, you sure aren't afraid of riveting and metalwork :) That looks like production airplane quality from the photos.

We had a camouflaged Grumman AA-1 based here at Whiteman airport for many years... was that you?
 

Tinbuzzard

Member
Joined
Feb 15, 2020
Messages
10
Location
Southern California
We continue with construction detail images of the wings...

Sparcap 1.jpg
Left main spar web, caps and compression blocks after alodining and zinc chromating. Caps are 2024-T3 bars, 3/8" by 2".

IMG_0034.jpg
Left wingroot after initial assembly. All primary structural bolts are 180,000 psi. external wrenching type. (Lot of good aircraft surplus places in So Cal) The heavy vertical hinge on the inner web is for a walking beam support for the aileron pushrod. It makes an angle at that point to follow the sweep of the wing.

RW Bay 1.jpg
Right wing inner bay before the last skin was riveted down. The heavy diagonal rib and .050" 7075-T6 upper skin transfers main spar loads to the rear spar if there is a root failure in the main one. The rear spar can keep the wing on to 2 Gees. (Lower RS fitting just visible at right edge)

LW Bay 2.JPG
Left wing bay 2 before upper .040" skin install. Bay 1 and root to right.

LW Bay 3&4.JPG
Left wing bay 3 & 4 after skins riveted to bay 2 and outer wing. Outer flap bracket on left, with aileron bellcrank above. Hinges on rear spar are for a roll control spoiler. This was the last section of the outer panels skinned to allow for control mechanism installation.

Aileron Bellcrank Parts.jpg
Some of the machined and formed parts for the aileron and spoiler control system. Aileron hinge brackets at upper left, machined out of 2024-T3 solid blocks. Obviously, I like to make stuff!

IMG_0001.jpg Left outer wing structure. As it's tapered and swept about six degrees, every wing rib is different. One finely tapered compression sparcap extends to the tip. The long taper cuts on all the caps (3/8" thick) were done on a table saw with a wood veneer blade lubricated with candle wax. Very noisy, but clean smooth cuts!

LW Aft Hardpoint.JPG
Threaded hardpoint at the outer rear corner of the first rib bay on the left wing. With another at the forward corner, this allows for a baggage pod, aux fuel tank, or whatever. They also serve as tiedown points. Empty holes on the double rear spar web are for a flap hinge bracket.

HypnoToad 113.jpg Watts linkage for roll spoiler deployment in bay 4 of left wing. Neutral position. Bit of aileron at upper left with the flap to its right. Silver colored torque tube and pushrod deploys the flaps. Red is aileron bellcrank; green spoiler pushrod.

HypnoToad 116.jpg Aileron and vented spoiler deployed for full left stick. Ailerons have a 2 to 1 differential, and spoiler timing and deployment amount are adjustable. A main design goal was for good low speed handling.

That's it for today; I reached my image limit!
 

Topaz

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Orange County, California
Now come on, be honest... that was built at the Lockheed factory...
You should see it in person. I used to drive down to Brackett Airfield (POC) now and again just to visit with Jeff and shoot the breeze about homebuilt airplanes, all the way back into the '80's. The airplane is absolute artwork and, yes, you could be excused for thinking it came out of a place like Lockheed. Beautiful work.
 

Jay Kempf

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Apr 13, 2009
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Warren, VT USA
Finally! So glad you're back. Someone needs to compete with Shannon for the making us all look bad prize.

Gawd I would love to see it in person. So much learning there.

Kudos
 

sdupre

Member
Joined
Oct 10, 2014
Messages
8
Location
Colorado
I'm new to HBA and just read this thread from the beginning. It's the most riveting firsthand homebuilding saga I've ever heard. (Never used “riveting" more appropriately.) The pictures themselves are inspirational. Looking forward to Tinbuzzard's upcoming posts and pictures.
 

Tinbuzzard

Member
Joined
Feb 15, 2020
Messages
10
Location
Southern California
Thanks everyone for the wonderful comments! Building this plane has been a form of therapy for me during the inevitable downtimes life throws at you, as well as just wanting an airplane.

We continue with structure aft of the rear wingspar.

IMG_0016.jpg Flap ribs and web being fitted to incomplete left wing. Early on, the plane was a 'T' shaped structure of just the fuselage keel and center section wingbox with the three landing gear assemblies at the ends. I built out from there using earlier sections as tooling for later ones. This worked well enough that upon first complete assembly, the pairs of measurements from the nose to points on the wingtips, and from there to points at the ends of the tailbooms were the same to about 1/8".

IMG_0011.jpg Inboard end of the right flap. (span 7'5') Actuating horn attached to end rib. There's another at the other end. The .025" wall, 1.5" leading edge tube gives the unskinned structure torsional stiffness so it wouldn't distort while I was drilling the skins! The skins are folded at the trailing edge and wrap around to, and are riveted into this tube.

IMG_0019.jpg Skin being installed. It overlaps at the LE with the rivets being near the static point of the airfoil when it's deployed. Some of the skin stiffeners (unpainted) are visible. Cutout in tube at the double rib allows the wing support bracket to nest there.

HypnoToad 056.jpg Flap LE and left wing rear spar attach fittings. The small pushrod from the actuating horn to the bellcrank in the Delrin bearing turns the torque tube that extends the outer end of the flap. The main flap pushrod fits between the horn plates and is moved by another bellcrank off to the right of the image.

IM000781.JPG Flap being test fitted. Deployment here is fifty degrees. That will be limited to thirty until flight testing shows how much safe deployment I can use without overpowering the elevator in the landing flare. This is a good view of in progress wing construction, and the last time I had them on the plane!

LW Joint 1.JPG Left wing to fuselage fairing, center section to outer panel joint, and a bit of the tailboom. CC to wing junction is a butt joint with a maximum gap of 0.010" and zero airfoil misalignment forward of the main spar. There are removable access strips aft of the spar top and bottom for the main wing bolts.

IMG_0032.jpg Right tailboom upper caps and rear wingspar fittings. A .080" web and heavy stiffeners and doublers react landing gear loads from the rear pivot. The front pivot bolts directly to the upper spar block with the rod end. You can see a bit of the LG strut at bottom center.

IMG_9364.JPG Since I was reworking the LG forks, I decided to remove the struts and retract linkages to upgrade everything. Strut with remachined fork and tire weighs 25#. The spherical pivot bearings were already machined flatter on one side and have a spreader fitting to provide more bending resistance for the 1/2" bolt that holds them.

IMG_9380.JPG Finally, today's effort! Cleaning and painting the wheel well. Left side, view outboard. Stainless steel retract link main pivot bolts through lower rear spar cap. I'll do the right one once this one is back together.
 
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