RE: Kingcat-Like Design and Build
 

LYNX

MALKIN

GRIMALKIN

PANTHER

BOB CT

LYNX CT

STRAYKAT

VEXATION

DOUBLE DUCE

RE: Kingcat-Like Design and Build
 

I am happy to report the nameless kit now has a name......."Modkat".

Just talked to David at BVM and he gave me the green light on the name! I really didn't need to call BVM for this but there still is honor in RC.

The Modkat is born [sm=thumbs_up.gif],

Mods

RE: Kingcat-Like Design and Build
 

very kool..... at least I was klose

RE: Kingcat-Like Design and Build
 

Did Bod fairly win a free kit :D ?

RE: Kingcat-Like Design and Build
 

Very nice, if the kit comes in at the price range you mentioned, it will definatly be on my list of planes to get. Can't wait to see the final product.

Joe

RE: Kingcat-Like Design and Build
 

Hey Bob,
You deserve most of the credit for this one. As many times that you have used "'k"'s in place of c's I am surprised you didn't get it first time around. :D

RE: Kingcat-Like Design and Build
 

I can do one better.... I need an experienced builder to be the "guinea pig" once I get the bugs worked out of the prototype. All that I would require is a detailed report of pros/cons once the build is complete. Then I can release it to the public.

Bob, you up for it?

Mods

RE: Kingcat-Like Design and Build
 

Fuse Design-Phase 2

Phase 2 is complete. The fuse has been mated with the wing center and the appropriate cuts have been made (figures 1-3). Had major issues when trying to incorporate a cowl because I had to widen and elongate the fuse to make it fit. Structurally it would work, but externally it was just.......ugly [:'(] (figure 4). It really ruined the "speed" look of the Modkat, so I'm leaving it off and sticking with the original fuse design (figures 5 & 6: fuse front and rear view).

Once the fuse was cut I spent a good chunk of time fine tuning the canopy shape (figure 7). The change is very subtle but makes it look a little faster even when standing still :D. To smooth out the underside I added a belly pan (figure 8). The belly pan will be molded it out of fiberglass. Then glued to the bottom of the wing center with epoxy and micro-balloons with scrap balsa underneath to support it. I would continue on and install the hardware, but I will not have the engine for another 2-3 weeks [:o]. The muffler will be routed through the fuse and I'd like to have accurate measurements before starting that.

In the mean time, I'll start designing the twin booms and elevator.

More to come,

Mods

RE: Kingcat-Like Design and Build
 

Very sweet. Can't wait to see the final rendering, let alone a first prototype.

By the way, I looked through the postings you linked to and also did some other research online about how to do fiberglass molds. It really doesn't look all that difficult, but I would imagine that the first few attempts would be challenging. I've actually started considering doing a mold of the fiberglass cowl I'm going to do for the Sig Somethin' Extra I'm building right now so I could reproduce it, not sure yet though. An initial investment for tooling gel coat, release wax and the various weights of cloth wouldn't exactly be cheap, but I'm sure it would be fun.

Keep it up! [sm=thumbs_up.gif]:D

RE: Kingcat-Like Design and Build
 

.
Making a cowl is an excellent way to earn your fiberglass wings. Have you heard of [link=http://www.cstsales.com/tutorials.html]CST Composites[/link]? That's where I buy all of my fiberglassing supplies and they even have a tutorial detailing the entire cowl making process. If you have questions call their customer service and they'll issue even more pointers. If you want to make a balsa cowl I also have an article detailing how to do that, but you would learn more trying the fiberglass technique first. In RC, fiberglass is your friend :D

Give it a try. You might like it,

Mods

RE: Kingcat-Like Design and Build
 

I didn't mean to give you the wrong impression, sorry about that. I'm definitely not a newbie when it comes to fiberglass. One of my other hobbies, which has stalled out for the time being, is high power rocketry. On the most recent rocket I built, I wrapped the entire airframe with fiberglass and vacuum bagged it. Not a quick job, but definitely fun. :D I have also built a rocket out of nothing but fiberglass components (commercially bought, I didn't make them). Pretty much the only things I haven't done with fiberglass are molds or something like a one-off custom cowl over a shaped foam core, which is what I'm going to do with the Somethin' Extra. And yes, I have heard of CST Composites and have gotten stuff from them before. [8D]

RE: Kingcat-Like Design and Build
 

LOL! Now I will attempt to remove my foot out of my mouth [sm=bananahead.gif]. Rocketry? That's what got me into r/c. Nothing above a "D" size motor, but it was fun.

RE: Kingcat-Like Design and Build
 

The booms have been shaped and are ready for framing. I've been contemplating whether to cut the plug out of solid basswood or use a combination of light ply and pink foam. The plan is to design a light ply plug and have it laser cut to shape and fill the voids with over-sized foam. Then, hot-wire the entire structure to get a rough shape. Once that is accomplished, add a few layers of light weight spackle and begin the long process of sanding/polishing the plug. IMHO the plane looks fast even at this stage [sm=shades_smile.gif].

Design Features

The Modkat will be able to completely break down for transport and maintenance. I find that even the best pilots have a bad day and total their planes [:o]. Sometimes the damage is isolated to a section of the aircraft and is deemed repairable; but in the case of fiberglass components, if the part breaks, that's it. This is the reason why I did not make the entire aircraft out of composite. In the case of a bad crash you can just get another part, install the formers, add paint, and you're on your way. If the wing is totaled, may take you a bit longer....

What's Next?

1. Make boom plug framework, formers, and extension wire tubes
2. Design Stab & Elevator

More to come,

Mods

RE: Kingcat-Like Design and Build
 

Looks sweet! I'm starting to get really excited. Even if it would be too much plane for me to fly with my current skill level, I still want to build it just to have it look pretty until I can actually fly it. I am a bit more of a builder than a flier, but this thing just looks so freaking awesome.

RE: Kingcat-Like Design and Build
 

Thanks. I'm guilty of that as well. Once I complete a plane and fly it 2-3 times it hangs on the wall. Then, it's on to the next project [sm=bananahead.gif].

RE: Kingcat-Like Design and Build
 

yea.....just ask him about that AWSOME skybolt he's only flew.....what mods? 6 or 7 times at the most.......LOL

RE: Kingcat-Like Design and Build
 

Uh..... more like 3 or 4 [sm=72_72.gif]. I got to fly it at least once this year to clear out the engine [sm=lol.gif]. My mom always said I had a one track mind.

RE: Kingcat-Like Design and Build
 

Mods-R-Me,
I'm doing a 3D design of the F1 Nemesis in 1 /4 scale or 63", I will be using a rear exhaust Jett .100L which is the same size as your Jett 90L, only difference is it will turn a 12" prop the same rpm as a 90 but with a lot more pitch. I have to wait until Dub gets back next week to see if he will actually sell me one as this is kind of a special motor if not it will be the 90L. Do you have a step file you could send me of the 90L (same motor as the 100L) as I use AC Inventor, I would really appreciate it. Very nice CAD work too.
Thanks,
LeeU

RE: Kingcat-Like Design and Build
 

Thanks and I'll send you a copy of the engine once I recieve it in two weeks. I've resisted the temptation to guestimate most of the dimentions from the Jett website so I don't have anything concrete right now. Would you like the 3D part or a 2D drawing of it? Also, what file format would you like it in? You want a two blade or three blade spinner?

Mods

RE: Kingcat-Like Design and Build
 

Mods-R-Me,
Thanks for helping me out. At work we use both Inventor and Solid Works, we save drawings as "step" files to go back and forth between the different CAD formats, works great. I would like to have the 90L and the two blade spinner if it is Jett in 3D if you don't mind. As more and more people start designing RC airplanes in 3D it would be nice to have a data base on this web site where we could keep 3D drawings of motors, servos and receivers, spinners etc.... so we could pull them into our 3D drawings as needed. It is amazing how much better one can design and build a RC airplane when it has been done in 3D CAD not to mention one already has the files needed for laser cutting. In Inventor (I know SW is the same) as I design an airplane I update the mass properties of each part as I go and end up with the weight of the finished plane and I also work with the CG before the first part is cut, cool.
Thanks,
LeeU

RE: Kingcat-Like Design and Build
 

This is very true. The simulated mass function is great. Have you tried a simulated "drop" test in Solidworks yet? Once you get the aircraft completed, add gravity, and set the height for 3 feet. Then use Cosmos to see where the most stress occurs. I'd post some pics of it but I still waiting on parts (engine)! What parts to do have modeled? I have SpringAir 701s, Oleo Struts, and Blue Bird Servos. We can exchange parts.

Mods

RE: Kingcat-Like Design and Build
 

Mods-R-Me,
I have Hitec 55's, JR 241's Himax 20 series motors, Cobria gear boxes or mostly foamy stuff in 3D.
I see your at Eglin, are you active duty? I'm retired AF since 03?
LeeU

RE: Kingcat-Like Design and Build
 

Got most of the Stabilizer and Elevator done today. I'm waiting on hardware to finish the remaining portion.

I've decided to go with the split elevator option because the airfoil is very thin and will only fit micro size servos. Knowing this, it will take at least two to move the elevator effectively during high speed maneuvers. The micro servos I chose (GWS Micro 2BBMG) have dual ball bearings, metal gears, and 76oz of torque each! Since the servos are very strong and the aircraft will be going very fast (hopefully :eek:), I chose the [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&W=000614822&I=LXMUB6&P=K] Sullivan Steel Control Horns[/link] over the regular nylon. I've seen a few speed planes crash and burn when the horns ripped off during a high speed pass ;).

Working with Solidworks is great because once you build the model, the plans are automatically generated. This also means that the model must be as detailed as possible because any irregularities will show up in the plans. This is why I am loading all the hardware that will be used for the Modkat into CAD. This way I can test all of the control surfaces in CAD before starting to glue my fingers together. The process began today with a few essentials (figure 1) and will add more as UPS drops them off.

The stab has a pretty typical construction: ribs, sheer webs, spars (figures 2 & 3). One challenging aspect was how to attach the stab to the booms. It had to be strong, light, and inexpensive. I settled on aluminum threaded couplers inserted into sections of brass tubing using JB weld to adhere them (exploded view-figure 4). The brass tube/threaded coupler assembly will be epoxied into the first three ribs (the first and last rib will be made of 3/32 ply).

The elevator hinge is of a different design. I wanted to avoid ordinary the razor planed "V" hinge and design something more sophisticated like this (figure 5). The convex "male" side would be fairly easy to shape, but the concave side would be a lot of work so I found a compromise (figure 6). This is actually the elevator hinge set up on the BVM Bobcat and it works so well that I'm incorporating into mine.

First, drill the hinge point holes as normal. Next, shape the elevator leading edge(LE) into a convex shape using a razor plane and sand paper. Then, cut notches into the elevator LE the approx the width of the hinge point (figure 7). After sheeting the stab leave ~1/4" extra hanging over the trailing edge (figures 8 & 9). Then, insert (dry fit) the elevator into the stab and find the pivot axis where the elevator can rotate without scraping another surface (figures 8 & 9). Lastly, chamfer the sheeting overhang to the shape of the LE.

Once the prototype is complete, I'll will start off with 30 degrees of elevator travel and fine tune it from there.

More to come,

Mods

RE: Kingcat-Like Design and Build
 

hmmmmmm.......that #5 pic looks familiar.........if i could only remember where i've seen it before...

it's almost like...........i can't quite put my finger on it........

LOL......j/k mods, looks like it's really coming along nicely.

RE: Kingcat-Like Design and Build
 

Looking great Mods. If you are starting a "pre-order" list, I want to be on it! :D

Spar