Hornet gyro measurement question....

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MadProfessor8138

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I'm not building a Hornet at this time but will get to it eventually,hopefully...the Stork has to be finished before a new build starts.
But I do love gyros and thought I would do some preemptive thinking and research for future work.
You guys have given some great answers and I really appreciate it.
I think my whole line of questions pertained to the numbers given and why they were quoted on the plans in that manner instead of more practical measurements for someone in their home shop.
As I stated before....I'm a fabricator but no where near being a machinist.
I thought the dimensions given were something that I didn't know that I didnt know......if that makes any sense.
Fabricator measurements and machinist measurements are 2 totally different things...

Kevin
 

TFF

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Some of that is what cad does not do well, decide what number is important and what is not. 6.099 is really 6.099999999999. Hand measured 6.10. It’s just the precise nature of drawing that way. If you have it round on its own, it might not be right either. The designer is supposed to get in there and fix that stuff or he expects you to know what he knows.
 

Aerowerx

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...(Typing paper, for those too young to remember, is like that funny paper they used to run through printers with holes all along the edge and perforations you could tear off.)
UH, no. You are talking about tractor feed printer paper. NOT the same thing as typing paper.

The present day equivalent of typing paper is as ink jet printer paper.
 

wanttobuild

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The Hornet plans are very accurate. There is no mistake. Your skill to execute the plan will determine what kind of airframe you will have, it won't be the plans fault.
I have read the full documentation and reviewed the plans and it will be a high level beginners gyro. The plans do not however cover a flex shaft prerotator or fixed shaft for that matter. I would like to see what the designer would have came up with. Would like to see a rotor brake but I will come up with that.
I am gonna stick to the fixed vert stab/hinged rudder, because as far as I know the flying rudder has not flown. I will have to do a little more reading on the matter.
Also I believe the Aussies banned the use of square tubing that does not have radiused internal corners.
 

MadProfessor8138

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wanttobuild.......are you starting a Hornet build?
I would be very interested to see what your costs are for the airframe construction.

Kevin
 

wanttobuild

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Torn between JT-5B and the Hornet Kevin. Welders don't like to bolt things together.
Maybe a 4130 Hornet!
I am busy this year with a house remodel. Large job, not to mention I work full time.
But next year I may build the JT-5 and the Hornet.
Gyrocopters will allow the opportunity for me to install a redrive into the airframe, thereby allowing the Crankshaft to do only what it was designed to do, Spin without any load imposed by a prop or socket. Its gonna work GREAT!

Ben
 

TiPi

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Use the bracketed dimension in mm. No conversion
Agree. Fractions don't cover all dimensions so there are decimals that don't convert to a fraction. Move on and use the metric system and the whole problem goes away :) We (Australia) have changed over a few decades ago (in the 70s) and haven't looked back.
 

wsimpso1

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Kevin
[/QUOTE]
Here is a quick example.....but there are many throughout the plans.
View attachment 87570
...

What is .058 ????
Everything on there is easy to understand and deal with once you understand how tubing is sized and sold. The inch dimensions are entirely even fractions. The 1.25 and 0.058 are tubing dimensions. 0.058 is a standard tube wall thickness, so they were specing 1-1/4x058 tubing. You cut off the right edge stuff, so that is hard to do anything with.

Billski
 

wsimpso1

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I understand the whole concept....so let me just say that.
What I dont understand are measurements in the plans such as :
View attachment 87577

My thoughts are you have little experience in reading drawings. I like to think you are not trolling us. Perhaps an EAA Sportair class in sheet metal is a good idea.

This drawing is not perfect, but is adequate. It also makes for a fine example of how to do this sort of part. The plans for many planes do not get into shop practice. I could build from that drawing and get exactly what they have in mind. I could also get contrary and get something really twisted... You have to take the attitude that you want to end up with it looking like the drawing.

First, note that there are two lines designated zero - those are considered datum or baselines for everything else. They establish our frame of reference. The only errors I found on this drawing is that the angle between the datum lines is not stated and the included 30 angle is not specified as being symmetric. I assume that that both are true - they do appear to be drawn that way...
  1. To make the part, I would start with a piece of 1/4" 2024-T3 plate big enough to get this part from it - 2" plus a little by 6-1/8";
  2. Straighten and square the two datum edges - you will use these edges for all dimensions. Saw, file, sand, checking that the edges are square to each other and square to the large flat surface;
  3. Cover one side with layout blue and let it dry;
  4. Set your dial or vernier caliper to 0.375 and scribe a line parallel to the long side using the long side to rest one leg of the caliper and scribing with the other leg. For most of us, this works pretty well;
  5. Repeat at 1.000, 1.425, 1.625, and 2.000;
  6. Now you get to do the same thing , measuring from the short side of the part at 0.500, 2.500, 3.974, 4.157, 5.474;
  7. You will now have a bunch of intersections of these layout lines, six of which are for holes, and one specifies a radius. Find the (1.000, 5.474) intersection, centerpunch it, then either use a compass or your dial caliper set to 0.625 to scribe the radius from that punched spot for later cutting of the bottom radius;
  8. Two intersections are to produce 5/16 holes, one at (1.000, 5.474) and one at (1.425, 3.974). You have already centerpunched one, locate and centerpunch the other, then drill them with 1/8", then 1/4", then 9/32" followed by a 5/16" reamer. Maybe they can be drilled to that size, but I assumed they needed reaming to size. Context of the plans will tell you more;
  9. There are four holes specified at 0.257". Those are most likely clearance holes for standard 1/4" bolts or rivets. Identify and centerpunch the applicable intersections, then drill 1/8", 3/16", and then an F size drill which is 0.257" and is a standard upsize for standard AN bolts or rivets. Context of how the part is assembled will tell you a lot. Bolted, and the drilled holes might be OK. If this part is riveted, these holes will be taken to size together with the part it will be riveted to - do not finish drill them now;
  10. Find the interesections at (0.000, 4.157) and (2.000, 4.157). You have an included angle of 30 degrees specified, that is 15 degrees on each side if symmetric. There are two ways of doing this:
    • You will need to set an angle of either 15 degrees from the a long edge or 75 degrees from the short edge. Align the angle device with the intersections and scribe the lines as they are shown on the drawing the radius scribed earlier should align with the lines. When in doubt, align the angled lines with the 0.625 radii;
    • Simple lay a straightedge from the (0.000, 4.157) intersection to the 0.625 radius like the drawing, and scribe a line. Repeat for the other side;
  11. Now you can saw the part from the plate, file to the lines, and deburr.
If I were just figuring this out, I recommend practicing layout on pieces of cardboard, then practice making parts from scrap or cheap stock. When you can replicate the drawing, right down to positions and sizes of holes, angles, and radii in scrap aluminum, then you can commit to that expensive 2024-T3 for the first time.

Billski
 

MadProfessor8138

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My thoughts are you have little experience in reading drawings. I like to think you are not trolling us.
On the contrary,I have a great deal of experience with reading drawings.....but there is a huge difference between wood work,sheet metal work,tubing work,fabrication work,machinist work,etc.
Each one has a different set of measurements and different allowable tolerances.
I have built wood aircraft,sheet metal aircraft and ultralights that use tubing...but I am not a machinist and have never seen dimensions given in the format presented on the Hornet plans.

Not sure why you would have any thoughts that I would be trolling anyone on the Forum for any reason what-so-ever.....???
That comment kind of stumped me so I will simply reply with :
I'm pretty sure that we have already clearly established whom the Trolls are and whom the Dreamers are on this Forum at this point.
If you need the list I can forward it to you....lol
I was laughing when i typed that so don't take it too serious.

I sat down and thoroughly looked the plans over and several things clicked into place as to how the measurements are laid out on the plans and what materials are being used...tubing,flat sheet,etc.
It just takes a different skill set and a shift in measurement comprehension to understand them.
In my defense,I showed the plans to several very accomplished & competent fabricator/builders and even a few of them commented that the build is certainly do-able but the plans weren't laid out in the best manner possible for someone building in their personal shop.

Your explanation on fabricating the part was excellent,thanks for that...enjoyed reading it.

I still intend to build a Hornet but it will have to wait until the RW-19 Stork is finished....

Kevin
 
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wsimpso1

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MadProf,

My apologies. I found no mysteries in the drawing, and could not fathom how anyone might have trouble with it. That just shows you how far I am from when I first learned drafting and building stuff some 50 years ago. We learned more about me than you there... So, with my not imagining how someone would have trouble with it, I wondered for just a brief moment if I was being played with. I prefer not to think such things on this forum... so I went ahead with a detailed description of how to obtain that part. Again, my apologies.

As to tolerances, most parts just show the basic dimensions - they are rarely if ever toleranced. Usually, we just do the best we can by scribing lines, using a sharp point on our centerpunch to find the intersections of the scribed lines, then work up to size on holes and work down to lines for finished edges after everything else is done. In this particular drawing, the odd numbers probably come out of trigonometry or other more than simple relationship elsewhere.

Unless you are ready to redesign the ship, I would not round dimensions on fittings. Really. The designer was probably putting both ends of some piece at some specific place in 3-D space, and thought that the hole needs to be "right there". The designer probably has another hole someplace with another seemingly odd dimension, and piece that goes between these two holes of a specific length. Start changing things and who knows where it will all end up? Or you may have another fitting that also captures the other end of a bolt or rivet, and they have to match. Watch for this sort of thing and build the pieces together that go together. As long as the design is rounded to thousandths, you can set your dial (or vernier) indicator or other scribing tool to the dimension and place the hole pretty accurately for later fit up. Then, if you have a couple things near each other in the design, your odds of having them bind or fight are reduced.

I once worked with a draftsman who would do the trigonometry, the tolerancing for fit up and process control, etc, and come with a dimension to 10 (TEN!) digits - that was how many digits his calculator displayed. The concept of significant digits was foriegn to him. We had to then get him to edit dimensions before we would sign off his drawings. Be glad your drawings are not done by someone like him...

Billski
 

MadProfessor8138

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wsimpso1.....no apologies needed at all....but thank you for offering one.

A major portion of the issue that I was having when I originally posted the message was the fact that I hadn't printed hard copies of the plans out.
While digital media is great for ease of storage,transport and transfer....it can be tedious when trying to see the big picture...one page at a time on a smart phone....smart phone but dumb operator....lol.
Once I printed the plans out and could look at several pages simultaneously things started to click together.
I would reference it to doing a jigsaw puzzle...find the border pieces,a known good starting point, and the rest just fall into place.

And yes,we did learn something about you from your post....you're educated,detail oriented and have the compassion to explain an issue to someone that was not comprehending the subject by writing an in depth explanation.
All positive attributes in my book and I thank you for your help......

Kevin
 

proppastie

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another suggestion....cut big, drill at assembly, trim last.
 
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