1/4 Scale Kayaba Build


I started the design of this project about 7 years ago but never got around to finishing the design work let alone cutting some wood to build the model from. Three jobs later and a move across the country I was inspired to finish some of my old projects after seeing a couple other Kayaba builds here that don’t seem to have been completed.

I spent about another 20 hours of Cad time to get it to the point I could cut out some parts. The design is still not complete but if I waited to figure out every thing a head of time it would be another 7 years before I completed the model.

Parts I haven’t completed figured out yet are the main landing gear, tail wheel, rotor blade construction, Head and control system. These MINOR details will be figured out along the way and I’m not bashful in asking for any suggestions. So if you seen some big autogiro out there and have knowledge to share, please do so.

I also haven’t figured out how I am going to access the main flight battery. By the way this thing is going to be powered by a 63mm out runner brushless motor. I don’t believe it will need this much power to fly but I’m sure I’ll need the nose weight anyway.

The rotor span on this model is 115 inches

Fuselage length is 64.25”

Estimated take off weight 16 pounds or less

I started this build Thursday night and got one side created. Friday after work I laid out the second side, let it dry for a few hours while I watch TV and then started putting the sides together for the next three and half hours. I’m using mainly Titebond 3 for the build so I need to let things drying before moving on. I will admit CA was need in a few areas while joining the fuselage sides together.

One photo show the first side being laid out. A second side is then made. Another photo shows the two sides on top of each other to show how close two separated sides can be made. I made the small bench disk sander about 20 years ago when I was making model bridges for weight testing contests. It is simply the best tool you can have by your side when sticks need to be sanded to the proper angle.

We now need to make a complete fuselage by connecting the fuselage sides. I again lay out balsa along the outside so the fuselage sides have something to follow and I get the proper bend. Lots and lots of small clamps are used to hold the side in place. I added the cross stick braces from the front and worked my way back to the tail. I made two identical length pieces for each cross piece. This way I was assured getting a square cross section to the fuselage. I glued one stick on top of the drawing while the second identical piece was located by using a couple of squares to locate the position on the top of the fuselage. During the build the top of the fuselage is actually laying against the building board but for now when I say top I actually mean the bottom. If every thing works out the top stick should actually line up with the vertical sticks that make up the fuselage sides. Use anything you can get your hands on to hold things in place while the glue dries including tape which is cheap and fully adjustable in length.

Later today I will get everything glued in place so I can begin adding he stringers to the rear of the fuselage and sheeting to most of the front end. I can’t complete all the sheeting because I still need to cut out some sheet metal for the landing gear anchors and figure out how I am going to design the rotor mast let alone how it is going to be anchored to the fuselage.

G'Day John
I can see that this is going to be one hell of a project,that I will be watching with great interest. I think I may be watching a master at work. Dont stop now.
Chris............

Here’s what I accomplish today on my third day of the build. I glued all the formers in place included the landing gear doublers. The metal landing gear brackets were cut out of .059” thick stainless steel. I don’t do metal and these things took me over two hours too make. One wood band saw blade and four drill bits later they’re good enough for their intended purpose.

I really need to come up with what I am going to use for a tail wheel before adding the stringers to the rear of the body. Once they are added it will simply be harder to get the tail wheel braces in place.

I still haven’t glued the motor box parts together since I didn’t put any right thrust in the model and I’m thinking maybe I should have. Any one out there have right thrust in their Auto Gyros? Please let me know if it is a must have or not.

John,
That is excellent, nice to see someone have a go at their own. Very refreshing.for me that is the best looking 'kellett' type autogyro ever made. Looking forward to your progress.

Regards

Rich

Looks great John! Do you have your own cutting machine? Would love to see it in action!
Joe

Looks great John! Do you have your own cutting machine? Would love to see it in action!

No I don't have one personaly but I have access to one or I get it done at http://www.laserlizard.com/

There's not really much to see but a head going over a piece of wood and a dark line being formed as the wood is being cut through. I will admit though it is cool since it makes life so much simplier. I do however have a CNC hot wire foam cutter. it's about as boring to watch as a laser cutter but again it makes life much simplier then making templates all the time like I did in the good old days.

John Boren

G'Day John
Re your thrust question. I believe the general rule is with 6 DEG down & 2-3 DEG right.
I can see that you are an accomplished builder,and I am curious to know if you have any Autogyro experience?
Chris......

I am curious to know if you have any Autogyro experience?

Thanks for the info on the right thrust. I know it's common on most scale war birds and figured in might be needed on a large autogyro as well.

I've flown a couple of other peoples Gyros and designed a small indoor one many years ago. There are a few photos and a video of it flying on my web site. So I would say I have a little experience at best with them.

http://www.johnboren.com/html/indoor_gyro.html


John Boren

Can anyone verify for me that the horizontal tail does NOT have any type of sheeting over the surface. Anybody know the correct airfoil section for the stab, I am sure it is the same stab as the one used on the US made Kellet since the Kayaba was supposed to be a license copy.

Can anyone confirm what the cross seciton of the Sub rudder look like. To me it looks like they simply spread apart a couple of tubes in the center to create a rudder that is narrow in the front and back and wider in the center. Does this sound right.

Since I am kind of stuck on what I want to do for the main landing gear struts, buy or make and I still haven't decided on what my mast and head are going to be like I thought I would work on the tail section.

Outstanding work! I think you'll find the struts easier to make, than to find a suitable strut on the market. Can't wait to see more posts.

Regards,
-Mike

While thinking about the Head\Mast assembly and the main landing gear I decided to work on the rear flying surfaces. Nothing to exciting here and I'm sure you've seen this done before but this is how I am laminating the 1/16" x 1/2" balsa together to form the outer edges of the stab.


MDF wood is cut to the correct contours to allow for the thickness of the laminated sticks. To help protect against moisture damage the bottom and edges of the MDF is given a layer of white packaging tape. Clear tape would be just fine but it wouldn’t show up in the photos as well. The outer perimeter piece is screwed to the base piece. The sticks are run under warm water until they are completely soaked. Excess water is then removed from the woods surface. Titebond 3 is then apply to the wide edge of the balsa. Lay each piece of balsa on top of each other, place in form, then, slide the inner form in place. I will most likely wait until tomorrow before removing the first laminate. If your in a hurry, thinned epoxy can be used so you can get a couple of these done in a single night.


John Boren

I’m not sure if this is of any interest to autogyro folks out their since the blades used on these birds typically use a hard wood leading edge but this is how I make twisted blades for my rocket powered Helicopter models.

I first CNC hot wire cut a piece of foam with the correct twist. Although not shown in the photos a piece of saran wrap would be placed over the bottom foam form. A thin coat of epoxy resin is then applied to each layer of balsa. Four pieces of 1/32” thick sheets are used in the photos below. These glued pieces are then placed in the bottom form followed by a layer of saran wrap on top. The top foam piece is then put in place. Next I wrap the foam together with masking tap in five places. I make of all three blades at the same time using three separate foam forms. I typically place a piece of plywood over the three forms and then lay as much weight on the top as I can find. The next day you pop the twisted laminated sheets out of the forms and airfoil the blanks just like you would if they were flat.

The last photo shows what the blades are used on.


John Boren