Home Built

[tonydenton]

ok yes i had help,

[asra]

Hi Tonywell done - nothing like persistence ;D

[asra]

I did not think there was anything good about having my wisdom teeth out - but at least I was able to spend the day drawing up the rotor head! ;DPlease correct me if I am wrong, but my understanding of how the rotor head should be set up is as follows - When the gyro is in steady level flight the rotor disc should be inclined back at 9o to the air flow. From that datum position the rotor head must be able to tilt 9o forward, aft, left & right.The basic design is for a single place gyro using a 5206 bearing. The pdf file that I managed to scrounge were for a gyro with a mast rake of 10o. My design has a vertical mast, so as far as I can see I have 2 options.[*]Use the standard design, but incline it back 10[/list]



o in the cheek plates, check dimensions in attached Jpeg - smaller and lighter rotor head, negligible difference to cheek plates[*]Modify design so that it is mounted square, but adjustments made to dead stops on lateral forks and length of longitudinal forks - refer attached Jpeg - bigger & heavierI am inclined to go with the smaller and lighter option - does anyone know of a reason why I should not????I have attached 2 jpegs of the finished 3D models - if any one is interested I will send you the 3D models via Email. The website does not allow me to attach skp files from Google Sketchup. Google Sketchup is a free download CAD system that cannot be beaten for value

[asra]

There is a way to post the rotor head CAD models

[asra]

Hi TimThe usual is to cut your cheek plate top at 9 degrees and mount your head at this angle. This allows the head to pitch from the centre 9 degree position, to full forward at zero degrees then full back position being 18 degrees. Your first picture is the required design (ALSO THE NORM)Your second design should also work but will exert an uneven force to the 2 pitch pivot plate bolts as well as trying to bend your 2 pillow blocks (not good). This would be my concerns Cheers SamL.............

[maulonir]

Tim,I agree with Sam, tilt the head back 9 degrees in the cheek plates if you mast is verticle.Sam,I don"t see how the second design will exert a bending force to the pitch pivot plate bolts any more than the first design, or why it would apply a bending moment to the pillow blocks ???Enlighten me

[asra]

Sam,I don"t see how the second design will exert a bending force to the pitch pivot plate bolts any more than the first design, or why it would apply a bending moment to the pillow blocks ???Enlighten me Gyro"s usually fly with a rotor disc angle of 9 degrees (at cruise) in S+L flight. If you look at this picture the torque tube is in the middle of the 2 pillow blocks. This is 9 degrees, and if you then draw a line through the spindle bolt you will see it intersects the pillow blocks at an angle. Therefore in S+L flight a bending force would be applied to them.SamL.........

[asra]

Time for an update.I have not been as productive recently - I got a little distracted making up some tooling to build the pod. Basically I don"t like working with fibreglass - sticky, messy, glass splinters, and if you get it stuck in the mould just chuck it in the bin!!! So the pod is going to have a basic Al frame with a propeller plate skin. To make the bulk head frame meant I had to roll the aluminium section to get the shape. I did not feel like spending $2,000 of a machine or spend the quoted $500 to get someone else to roll it (with not guarantee of result), so I made my own section roller which worked pretty well in the end. It took me about 30 hrs and $50 to make the section roller, and it only took 3hrs buggerising around with a few trials to get an acceptable result. A few tips for those that are interested.[*]Best if you anneal the Al before you try to roll it - use a propane torch (with oxy you could end up with a puddle of Al) for about 10 min then quench - when I did not anneal the Al cracked on the 150mm rad!!![*]I have used a square section and after annealing better to collapse the inner radius wall, because as you roll the section the inner radius wall is under compression so it either has to grow thicker (won"t happen) or it pushes out the side walls which jam on the section roller flanges - I used a 3/8 piece of rod and laid it along the wall and pressed it down with the garage press to collapse the wall evenly.[/list]



To make it easier I have made up the dash bulkhead out of 3 pieces, I used 15.8mm X 1.5mm square section, the 12.7mm X 1.5mm is perfect to use as a dowel pin at the joint join!!!

[Gleeso]

Nice work there Tim.Matt

[asra]

Ok - finished marking the calves for this year and the veranda is painted, so I should have some time to build the gyro! :P ;DThe subframe for the pod is together for the main section, and the basic concept for the dash layout complete. I have left plenty of space for up to a 7" electronic screen, with the main instruments up the top close to the line of view. The cladding is at this stage going to be thin sheet aluminium - not sure what thickness would be best, 0.6mm or 0.8mm. I am thinking 0.6mm, but has anyone some experience of what works best?Built the pedals as well, the main section being 50 X 25 X 3 Al and the main foot rest member is 19mm X 1/8" chromemoly, the foot peg is made from 19mm X 1/64" chromemoly. To hold the foot peg in, I reamed the 19mm hole in the Ally so it was a good fit around the foot peg. I then pressed in a plug made slightly oversize on the ID of the foot peg to expand the peg and lock it in place. Seems to work bloody well.Throttle and trim adjuster are complete. The throttle has 2 discs of nylon bearing material that rotate against each other creating a firm but smooth throttle adjustment that will not change settings other than by the operator.Trim adjuster works well using an M12 piece of all thread - but nut sure if it is unnecessary ballast, time will tell.

[quoj]

Hi Kawasaki,I have a question re: joystick design.You see, I"ve noticed that there used to be two main designs of joystick:1) a lump of aluminium tube bent down and underneath the seat to a point about which it can rotate in two axes, which then connects onto your standard Y-shaped bracket which connects to pushrods and up to the rotorhead assembly.2) a vertical stick that connects to tube connected at both ends and rotates about an axis and with a parallel tube moving fore and aft, all connected to your standard Y-shaped bracket which.. etc etc.Now I"ve noticed the *third* design which I believe Birdy refers to as a "Rocco" design which is all done by pushrods from where the stick mounts in front of the pilot"s seat, as you have on yours.Tell me, what are the advantages with this design?Does it reduce vibration from the rotor at all?Are their other advantages/disadvantages to it?Thanks.

[gyroo]

Hi Quoj,I"ll buy into this thread as well with a few comments.The bent aluminium or tube stick running back under the seat to a single pivot block is commony called a "pump stick".The vertical stick that pivots side to side via one longitudinal tube and back and forth via a second parallel tube is customarily called a "Brock stick".The 3rd arrangement that Kawasaki is using I"ll call a "mixer", because that"s the expression used in helicopter engineering.Pump sticks are the simplest, but have 2 unsatisfactory characteristics. First is that the stick pulls up as it is pulled back, whereas it pushes downward as it is pushed forward. This is usually not a problem and no-one notices it much after a few hours of use. The second unsatisfactory characteristic is that with vertical g-loads such as during bad turbulence or a landing bounce the pump stick can stroke down and forward or back and up depending on which way the g is loading, regardless of what the pilot actually intends to do with the stick. Worst case scenario is that this unwelcome and unintended stroking of the pump stick may exacerbate any transient pitch instability and contribute to PIO. Unintended stick-stroking is strongly suspected as at least a contributing factor in a number of PIO gyroplane fatalities.Brock sticks and Mixers usually both have the benefit that the pivot point for the control stick is usually more or less vertically under where the hand rests on the stick at neutral, and so vertical stick stroking due to g-loading can"t readily occur. Of course, stick deflection as a secondary effect of g-loading CAN still occur if parts of the control run are heavier on one side than on an opposite side, but this effect is usually very minimal indeed.Mixers are most commonly used in helicopters because the control system has to accommodate for both cyclic AND collective pitch changes. Mixers are not usually necessary in gyroplanes because there is no collective. However, quite a few factory 2 seaters have mixer type arrangments to route the controls out of pods and around other airframe components. I have a personal preference for the parallel Brock arrangement because the deflection geometry can be easily understood and it usually has less linkages or pivots than a mixer arrangement. This is not a criticism of Kawasaki"s choice, because the essence of homebuilding is responsible experimentation and diversity in design. If everyone built the same way there would be no advancement. As Tech Manager, all I ask is that everyone makes sensible design choices based on proper research and an awareness of the pros and cons of each alternative arrangement they contemplate, evaluate and eventually settle upon.In Kawasaki"s arrangement it can be seen that the side-to-side and forward-backward movements of the control stick are converted to purely longitudinal movement of the 2 longitudinal tubes running back from the front mixer, then "re-converted" back to useable side-to-side and backward-forward motion by the rear mixer. Nothing wrong with that, but with this arrangement it is quite commonplace for it to be discovered at a fairly late stage that the amount of side-to-side deflection ultimately up at the head can vary depending on where the stick is held between the fore and aft stops. This may or may not become a problem.Brock sticks and Mixers can be set up - for instance - to "deaden" pitch sensitivity with forward stick. This might be useful because forward stick is usually associated with higher speed flight (and higher pitch sensitivity). It is quite easy to set up Brocks and Mixers so that 5mm of forward stick near the forward stop might only result in 2 1/2mm of forward pitch at the head, whereas 5mm of deflection with the stick near the rear stop might equal 5mm or more pitch at the head. NOTE: These measurements are purely arbitrary for the sake of illustrating my point, and ARE NOT indicative of any specific setup arrangement I am recommending.P.S. - Good work so far Kawasaki. Of course, I am sure you will eventually replace all the black and grade 5 hardware with AN hardware just before the TA"s inspection? I always use cheap hardware or UNF fasteners when I am assembling and re-assembling a gyro during construction then once all the fastener lengths are worked out I then head off and get a complete replacement set of brand new AN fasteners.Cheers,Mark Regancurrent Tech Mgr

[quoj]

Thanks. That"s good advice, Mark.I look at pump sticks and something in my waters tells me that they"re not for me.The Brock stick, to me, looks simple and robust.The mixer design looks a little more fiddly and with more small components that can fail but I was hoping it came with an extra advantage such as lessening transmission of vibration.I think someone mentioned that, ultimately, vibration and stick shake come down to rotor balancing. Whilst I"m sure this is true, I am wondering if there are other things that can be done to lessen the effect of a wobbling stick in your hand?Thanks.

[aussie_paul]

If the Brock stick is manufactured, as Brock did, using "bushes" at the wear points the play in the system gets really sloppy really quick. In have seen Brock set ups that you had to move the stick grip 40mm before the rotor head moved.In saying that some sloppiness does reduce some types of rotor shake.Aussie Paul.

[asra]

Well I think Mark summed it up perfectly!All I can add is the background as to why I chose to go with the mixer option. The biggest factor was space, on my particular design with the big 70ltr GG tank plus with the keel on a 9deg incline there isn"t much space in around the mast / seat junction. By using the mixer it has given me far more freedom in the location of the control rods to get them past the seat. I also read the article written by Mark in the Autumn edition of the "Gyro News" titled The Great Stick Debate and that certainly put me off the option of a pump handle. Pump handles are probably the most simple to make, which usually means the most reliable, but that extra degree of freedom in control (up and down pressure on handle as well as forward and aft) and the effect of any "sudden vertical acceleration is likely to cause the stick to stroke down leading to an unintended pitch input". This added instability is not what I need as a novice gyro pilot on my first solos!!!!My particular design of mixer uses large nylon bearing surfaces. By changing the tension in the main bolts you can significantly change the amount of friction in the control system, that translates dampening control. If the rotor has an issue with vibration I would rather minimise the vibration than use dampening to minimise the transmission to the pilot. If you try to dampen the vibration the energy has to go somewhere and is likely to cause fatigue to the system. This means that something is more likely to break at some point in time. As you have said Mark the bolts are just holding it together until it is finished, then they will all be replaced with AN on final assembly.Thanks guys for your input - this forum has been a great help for a first time builder like myself.