Crescendo Build

First pilot

Newbie
Joined
May 27, 2017
Messages
79
Location
Windsor Canada
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Steady progress on some detail elements of the airframe. Per Jake's direction in another thread I added .0625" of offset clearance between diagonals at the tie point. A stainless steel caliper mic is handy for scribing layout lines on aluminum. In the 2'nd closeup photo you can see a very slight gap between the keel and tailboom tubes. This is to account for the thicknesses of the powder coat finish (2 X ~.004") so the thru-bolts don't bind. I adhered tape of that thickness between the mating surfaces of the tubes before doing any transfer punches. The tailboom tube in the last photo was angle-cut to match the forward plane of the seat support angles via transfer scribe once all of the structural terminations were finished. Nice to see things turning out like the 3D model. But it is more time consuming than I expected tooling up for so many different compound angles.
Hello Brian, I hope you don't mean an actual scratch mark on Alum?? Every scratch ( even a lead pencil mark) will result in a potential crack. A felt tip marker is the surest way to avoid cracks on Alum.
tony.
 

Brian Jackson

Platinum Member
Joined
Jul 17, 2004
Messages
3,313
Location
Hamburg, New Jersey USA
Aircraft
GyroBee Variant - Under Construction
Hello Brian, I hope you don't mean an actual scratch mark on Alum?? Every scratch ( even a lead pencil mark) will result in a potential crack. A felt tip marker is the surest way to avoid cracks on Alum.
tony.
Hi Tony, and thank you for the heads-up. No scratches on the airframe. If I understand your question correctly, it may have been asked because of my use of a caliper mic to scribe 'layout marks'. I believe I used this term incorrectly. I meant to say 'Cut Lines.' As you've pointed out, even tiny scratches are bad news once they propagate, and I have been extremely careful to prevent this. Any marks placed on the airframe that aren't cut lines were usually drawn with fine-tip marker or pencil over translucent Scotch tape for the reasons you've described. Hope that clarifies things, and thanks for the good eye on that descriptive detail.
 

First pilot

Newbie
Joined
May 27, 2017
Messages
79
Location
Windsor Canada
Hi Tony, and thank you for the heads-up. No scratches on the airframe. If I understand your question correctly, it may have been asked because of my use of a caliper mic to scribe 'layout marks'. I believe I used this term incorrectly. I meant to say 'Cut Lines.' As you've pointed out, even tiny scratches are bad news once they propagate, and I have been extremely careful to prevent this. Any marks placed on the airframe that aren't cut lines were usually drawn with fine-tip marker or pencil over translucent Scotch tape for the reasons you've described. Hope that clarifies things, and thanks for the good eye on that descriptive detail.
Yes1 it was the scribed lines that woke me up.
Excellent work Brian.
Cheers,
Tony.
 

Brian Jackson

Platinum Member
Joined
Jul 17, 2004
Messages
3,313
Location
Hamburg, New Jersey USA
Aircraft
GyroBee Variant - Under Construction
Been a while since I posted on this log thread. Have been busy with the build and will be dropping a ton of pics in the next few days. The day before thanksgiving I had the rare opportunity to meet an extremely well respected member of this forum who did a basic examination of the airframe. Must admit it was a little scary... nobody wants to find out years later there's a fundamental flaw in the design. There were a couple of issues brought up that I am going to address. Fortunately they are minor fixes and will only involve remaking the two tailboom anti-twist tension struts. The general consensus I believe was so far so good, for which I am very grateful. Having an expert eye on the details is reassuring. And I've made a couple new friends who I got to know on a personal level outside of the forum. That doesn't happen often enough.
 

Doug Riley

Platinum Member
Joined
Jan 11, 2004
Messages
6,620
There are precious few of us gyro folk left in the cold, wet, breezy northeast. So it's not hard to finger the culprits.

Yup, we had a pre-turkey-day look at Brian's spotless shop and his elegant customized Gyrobee.
 

Brian Jackson

Platinum Member
Joined
Jul 17, 2004
Messages
3,313
Location
Hamburg, New Jersey USA
Aircraft
GyroBee Variant - Under Construction
A few operation photos... more to follow. Iphone is proving painfully slow at sending pics via email.

The last major airframe structural members are the forward seat supports. The seat tank is supported and fixed at multiple points along the underside and back. I will show detailed photos of the design and assembly in upcoming posts. This post just shows the steps that were needed to ensure accurate cutting angles of the airfoil tubes. Where possible I've used airfoil shapes below the thrust line to minimize drag. More on that later.

The hardest part I've learned about working with airfoil tubing is how to clamp it down without some flat external feature. Especially since every end is a compound miter on this design. One solution that has worked extremely well is a 'box clamp' I made of 2" x 4" rectangular tubing (see image 1). From left to right the components are:
- Pair of plastic wedge shims (inserted from opposite directions
- 1/4" plexiglass strip running full length of box tube
- The airfoil workpiece to be cut
- 2" wide aluminum channel
- Two 1/4-28 bolts threaded through box tube

Pressing the wedge shims inward together pushes the plexiglass against the trailing edge of the airfoil. Plexiglass, I discovered, has a surprisingly good grip on aluminum, even with relatively light pressures. I used a laser and mic to get the chord line perfectly parallel with the box tube. Once true, I wrote down the trailing edge distance from the box tube bottom for repeatability. .7550" in this case. The clamping screws align with the apex of the airfoil camber, and the channel distributes uniform pressure down its length.

Interestingly, modest (but adequate) clamping pressures don't really deform the airfoil tube. Instead, it tries to elongate the tube in the chordwise direction but only succeeds in adding more pressure between the plexi and the trailing edge, which is good. Even when the screws are only finger tight it's very difficult to wrestle the airfoil tube out of its set position.

The other piece of the puzzle was establishing the exact cutting angles on both axis. Miter gauges on most cutting tools ABSOLUTELY SUCK ASS! You're lucky to get it within a degree, let alone a tenth. Anyone following this thread knows I'm a huge fan of paper templates, provided the printer is properly calibrated. I printed various triangles of the different angles needed to set the blade and miter gauge, then spray-glued and cut out on cardboard with a straightedge and Xacto knife. Way more accurate than could be done eyeballing a questionable reading on the tools' angle indicator.

Anyway, lots more to share over the next few days. The seat install is nearly complete so I'm sorting through a million pics to find the ones that tell the story the best. Cheers for now.
 

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Vance

Gyroplane CFI
Joined
Oct 30, 2003
Messages
16,820
Location
Nipomo,California
Aircraft
Givens Predator
Total Flight Time
2400+ in rotorcraft
Those are some lovely parts and some nice fabrication work Brian.

Thank you for sharing the fun.
 

All_In

Gold Supporter
Joined
Apr 21, 2008
Messages
15,851
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San Diego, CA. USA
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Piper Archer, Aviomania G1sb
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Not sure over 10,000+ logged FW, 260+ ultralights, sailplane, hang-gliders
Brian, you do the most excellent work!!!
Dennis/GyroTechnic made his ride. Everybody raved about his machining as we are yours.
Then he started manufacturing them.
 

Brian Jackson

Platinum Member
Joined
Jul 17, 2004
Messages
3,313
Location
Hamburg, New Jersey USA
Aircraft
GyroBee Variant - Under Construction
Thanks, Jon.

Denis is on another level. Amazing stuff, and mad props (forgive the awful pun) to him for setting up shop. I'm nowhere near that skill level, but am only building one. Might be all my lifespan allows.
 

Brian Jackson

Platinum Member
Joined
Jul 17, 2004
Messages
3,313
Location
Hamburg, New Jersey USA
Aircraft
GyroBee Variant - Under Construction
Continued from yesterday, some more progress photos of November's work. This phase was for the 'Foot' assembly of the forward seat V-brace that attaches to the keel. The V-block is an internal part that receives the bolts through the Foot and the two airfoil tube supports. In addition to the center bolt (not shown), the V block and the Foot have matched anti-rotation pin bores to prevent the V-block from twisting. The head of the unitizing bolt is counterbored underneath the foot and is completely captured by the keel tube, making falling out impossible in the event it loosens.

The foot block itself will be trace-cut and ground to the exact shape of the airfoil tubes where they miter together at the bottom. The edge will be beveled to match the width of the keel. That part will be done last once everything is test fit, drilled and bolted. The final shape is visible in the rendering posted yesterday, and will be chrome finished like the rendering. Same finish on all the lathed parts as well.

The last pics just show the initial checking of the miter and block angles. Used my table saw blade as a support surface to get an idea if I nailed the cut geometry. Am currently making a jig from aluminum honeycomb (see image 6) before the final bolt holes are located.

The seat has been raised substantially from the original Gyrobee design. Plus it will have fuel in it. Beefing up this element to span the added distance and support the extra weight of a dangerous liquid gives me a little more comfort. There are additional support elements but will cover those in an upcoming post.
 

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