Crescendo Build

Brian Jackson

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Here is the Tie Channel concept (shown Green) mentioned above. Not shown in the screenshots are small compression spacer tubes the bolts will pass through that span the inside walls of the channel. This allows torquing the bolts without deflection of the parts.
 

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Jazzenjohn

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Your cad renderings are really Fantastic Brian! Beautiful job with them, they illustrate so clearly. What program do you use?
 

Brian Jackson

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Jazzenjohn;n1134212 said:
Your cad renderings are really Fantastic Brian! Beautiful job with them, they illustrate so clearly. What program do you use?
Thanks John. Rhino has been my tool of choice for sketching and fleshing out ideas.
 

Brian Jackson

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She's coming together like a Swiss watch. The tie channel between the engine support diagonals runs continuous to the mast (.060" separation from mast) rather than ending at an arbitrary distance midway. This arrangement has the benefit of reinforcing the diagonals at the point they are bolt-clamped to the mast. It also eliminates an additional hole midway down the diagonals (per the earlier rendition in post #21), transferring the load directly to the existing mast clamp bolt.

It does add a few precious ounces to the airframe, but structurally I feel it was worth the effort and slight weight penalty since the original 'Bee was designed around the lighter, less powerful 447 in lieu of the 503 being used here.

There's work being done to the Keel so it is not shown in the correct location in the photos. Still setting up the new lathe and learning how to adjust and use it for the axle strut connection inserts. Many new skills are being learned and honed.
 

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gyrojake

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Lookin good !!
The workmanship is awesome and adds to the detail of the build.
Clamping or bolting the angle to the mast will offer you more rigidity to the motor mount and stop wear from vibration. The angle embedded with the channel.
 

Doug Riley

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Hey, Brian: Is there a reason you (so far) haven't run a brace from the engine mount down to the tail tube? The loads on the tail tube from tail-down landings are a bit high for a completely cantilevered 2X2. Tailwheel-first landings are even more likely on a 'Bee than on other Bensen derivatives, since the 'Bee's tailwheel is quite close to the ground when she sits on the three mains.

Ralph left out a brace in this location to make it easier to remove the tail tube and rock the craft back radically to get it through a normal residential-height garage door. I actually did this little maneuver many times with my 'Bee. I always feared losing my grip and dropping the bird backwards, though, with the full engine weight landing on the prop.

Note that Bensen's first iteration of the B-8M had one pair of braces from the engine mount down to the rear keel tube, but he later increased that to two pairs, and finally to a stick of 1x2 x.125" rectangular extrusion. All this with a shorter tail tube, and tailwheel higher off the ground in the nosewheel-down stance, than the 'Bee has.

Something to mull over, at any rate.

Lovely workmanship, BTW.
 

Brian Jackson

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Doug,

Thank you for the critique and insightful explanation. I, too, have often thought this was the weakest point of the airframe for precisely the same reasons, albeit without the benefit of flight experience. I have seen others run a vertical 1X2 between engine mount and tailboom, which I believe the Hornet uses as well. My fear was, on the stock GyroBee, this could impose a substantial upward load on the engine mount on hard tail-first landings, compounded by the leverage a long tailboom imparts. So knowing the impressive safety record of the 'Bee I shelved the idea. I may dust it off and reconsider now that you have felt it important enough to bring up.
 

Brian Jackson

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It has been an educational month setting up, tuning up and learning the new lathe, starting with a complete tear-down and lube to get familiar with every nut and bolt. The photos are of my first lathed part finished yesterday; one of 2 matched inserts that attach the axle strut tubes to the keel. Not shown in the photos is a double-counterbore at the tenon. The inserts are slightly shock isolating, and I'll post a detailed design drawing here in the next few days that shows the inner workings and connections. There are no aluminum threads in the design.

The last photo still has the base attached (where the chuck grips) that will get removed. I also learned that wet-filing with oil works better than dry for the hand work. And blue dye helps with blending the stairsteps... when the blue lines in the grooves disappear you're done.
 

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Brian Jackson

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Purchased a longer bit to thru-drill the inserts. Looks a bit odd in the drill press but this setup actually worked flawlessly. There is a 1" diameter hole in the bed of the press that by chance allows a perfect fit of the tenon with a few thousandths of comfort clearance. The first 2 inches was drilled in lathe using a stationary bit in the tailstock chuck. The lathed hole acts like a drill guide, even though the part is centered and upright.

I can only bore 1/8" max. depth at a time before having to remove the chips from the drill flutes. Since the press has 2" total travel it requires me to crank the bed down to free the part and bit for cleaning... and there's a lot of 1/8 inches in a 5" part! I'm generous with the cutting oil but it's slow going. The 5/8" dia. x 2" counterbore from the tenon end will be a separate tooling setup I hope to finish this weekend.
 

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Brian Jackson

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Big day. Just bought a new set of Gyro-Tech blades and hub bar from a great gentleman named Carlos at Helicopters International LLC in Florida. The photo is one he sent to me of the blades still in the crate. These are the "Modified Airfoil" style that Gyro-Tech is no longer producing, but are designed for greater lift at lower speeds... "floaters", which very much describes the ship they will attach to. More information will be posted later, but this marks a major milestone not just for the build but for the bucket list. The dream is being realized after a couple of false starts from a past life.
 

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Brian Jackson

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This week was filled with many detail items I've been putting off until the larger tasks were completed. Among them is preparing the seat bottom for safety and installation. As mentioned in an earlier thread, I am adapting an office chair for service as the pilot's seat. The substrate is extremely rigid (3/4" cross-grain laminate) yet fairly light for its strength. Very little deflection when my entire weight is applied.

There are threaded steel inserts in the substrate that accept 5/16" bolts from below for attaching the base unit to the seat bottom. This is great if you're building an office chair, but not so great if you're building an aircraft. Even though the inserts have a fairly wide flange over the top surface of the substrate, I would not trust the integrity of an unknown metal, nor the pull-out strength of its design. So I removed the leather upholstery and separated the substrate.

The inserts can be left in place because their top flanges will act like flat washers. However, new bolts will be installed through the inserts downward from above, with the heads bottoming out on the inserts and the bolt threads protruding past the bottom surface of the substrate. This creates 4 threaded studs that can be nutted and safety wired through the attachment plates on the airframe.

I am also re-conditioning the leather before re-wrapping, and a few other detail touches. The separate seat back has been reworked and installed with a similar strategy, though with backer plates at the attachment points.

I'm working on a more comprehensive builders log with many more photos than I've posted here. I will share the link when it's in a more comprehensive form.

Rotor blades should be here around Wednesday the 8th. Much more to follow.
 

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eddie

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Brian the blades look great,it appears that the trailing edge is reflexed up they should work just fine.
 

Brian Jackson

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eddie;n1136370 said:
Brian the blades look great,it appears that the trailing edge is reflexed up they should work just fine.
That's what I'm told, but don't yet know how the profile differs from yours, at least until GT Poland provides the airfoil plot data. Not sure how easily they hand-start either. They are heavier blades than on most Bees (66 lbs re: specs from GT), so will have the effect of raising the CG slightly, and the seat is raised as well. The hope is to decrease the HS negative pitch requirements from 3 degrees to 2. Will cross that bridge later.
 

Brian Jackson

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Awaiting arrival of new Gyro-Tech blades and hub. Freight company scheduled delivery for this afternoon. Ever feel like a kid at Christmas? Really need to brush up on my whining skills when I look at my watch.
 

eddie

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Hey Brian have you quit your happy dance long enough to look at you blades.How do they look to you.
 

Brian Jackson

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Well I'm still sporting a big grin this morning. To say these blades and hub are well made is an understatement. They came crated in bubble wrap and the hub still had a light coat of machine oil. Packaging was excellent. The blades are more rigid and solid than I expected, and the finish is beautiful. Quality of machining is perfect. And they sure are sexy.

A huge thanks to Eddie for his great reviews, through which I was first introduced to Gyro-Tech. And many thanks go to Carlos at Helicopters International for making the purchase so easy. Great guy. And to GT Poland for support and provision of info. Think I made the right choice.
 

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gyrojake

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Here is a pdf with info on 8-h-12 air foils.
Some say they suck, but that is all I fly and love em.
If the reflex is set right you will have many hours of fun, care free flying.
Some say they are failed Helicopter blades and they are, but they are AWESOME Gyroplane blades.
There are many complex design aspects to an 8-h-12 that make them suck for powered flight.
Once you get them tuned in, I'm sure you will enjoy them
 

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Brian Jackson

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gyrojake;n1136490 said:
Here is a pdf with info on 8-h-12 air foils.
Some say they suck, but that is all I fly and love em.
If the reflex is set right you will have many hours of fun, care free flying.
Some say they are failed Helicopter blades and they are, but they are AWESOME Gyroplane blades.
There are many complex design aspects to an 8-h-12 that make them suck for powered flight.
Once you get them tuned in, I'm sure you will enjoy them
Thanks for the great info, Jake. I will pore over it in greater depth this weekend. Have always been fascinated how subtle changes in shape can have such drastic effects... like the Butterfly Effect is to weather. These are the "Modified" 8H12 airfoil which GT Poland will be sending me an airfoil plot grid of when their drafter returns from vacation. I'll post it on RF.
 

eddie

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Gotta agree with you Jake about the 8H12 Blade,I have flown other blades and they just don't have the performance that suits my style

of flying,they are kind of like the clark Y airfoil for fixwings it was the airfoil of choice for the early low powered slow flying champs,T craft,

and pipers of that era,they worked really good on aircraft under 110 mph,as speed increased the airfoil was abandoned for faster ones.
 
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