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Gunsmithing My weekend project. . .(not gun related)

LRI

LRI

Lance Criminal
Full Member
Minuteman
    • Mar 14, 2010
    6,314
    7,426
    52
    Sturgis, S. Dakota
    www.longriflesinc.com
    Took a Sunday to piddle with one of my RC plane projects. This started about 2 years ago with an idea that lead to a 3D CAD model and finally some machining. I made a case half about 18 months ago and decided to change some stuff. So, here's the latest:

    80cc nitro death! Here's the front case half being made. Only about 20 more parts to build. Someday. . .

    Surface model of front, rear case halves with cylinders:

    DSC_0022.jpg


    Front case:

    DSC_0021.jpg


    1st op: Making the crank case:
    DSC_0009.jpg


    Crankcase completed:

    DSC_0028.jpg


    Onto 2nd op: Profiling the outer case. This was done in one setup with only 5 tools! A 3/4" carbide lollypop mill to rough, a 1/4" bull nose that I ground myself for finish profiling, a 1/2 em to bore the bearing register, a 45* chamfer mill to break the edge, and a 5/16" em to spot face the bolt holes.

    DSC_0015-1.jpg


    DSC_0016-1.jpg


    /
    DSC_0019.jpg


    The one on the left is a piece I started on over a year ago. I decided not to work on the cylinders on the final piece just yet. I want to wait until I get the rear case done. I'll then assemble and machine as one piece. Much easier to get the cylinders in the proper location that way.

    Just something different to do. Actually this is a sort of self taught "primer" for machining stocks and molds for stocks. Something I hope to gravitate towards later this year. Be nice not to have to wait 12 weeks anymore.
    smile.gif


    Have a great Monday germs.

    C.

    DSC_0020.jpg
     
    Re: My weekend project. . .(not gun related)

    Wow, very nice. My Brother sells PAL Model Products 1/4A and 1/2A nostalgia replica engines. He contracts them out (not to China). So I can somewhat appreciate what's involved in what you're doing.

    Greg
     
    Re: My weekend project. . .(not gun related)

    Thanks.

    Here's what I hope to do with this. If you watch the Vid you'll see the name "Marty Flood". Marty sold me my first USRA Formula One plane. It's a Kelly F1. I have a new Kelly airframe waiting for this engine.

    <object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/zF1GOdpf45I"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/zF1GOdpf45I" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>
     
    Re: My weekend project. . .(not gun related)

    Noisy little bastards
    smile.gif
    How fast are they going? Seems like wearing a hard hat might not provide much protection from one of those.

    Kc
     
    Re: My weekend project. . .(not gun related)

    The unlimited and experimental class runs almost 250mph (actual)

    In the Formula Pro class (what I hope to copete in) they go around 190-195mph.

    Gallon of nitro a minute! Woo Hoo!

    Later,

    C.
     
    Re: My weekend project. . .(not gun related)

    Nope. I'd rather "cheat" with an engine that smokes everyone and ends up out in front.
    smile.gif


    Power is half the battle. Getting the turns right, fuel delivery, and just general pilot skill is a whole skill set in itself.

    Very humbling at times.

    35+ G load when cornering. Developing a fuel delivery setup that won't lean out when "banked and yanked" is a daunting enough task in itself. I hope to figure out an electronic fuel injection setup for this. (hope being a key word)

    We'll see!

    C.
     
    Re: My weekend project. . .(not gun related)

    Wicked little planes,and looks like another $$ hobby.
     
    Re: My weekend project. . .(not gun related)

    Considering that an engine is close to $4K you can quickly understand why I've elected to build my own.

    So far I have just my time and about $300 in cast AL billet stock invested.
    smile.gif
     
    Re: My weekend project. . .(not gun related)

    80CC?! in a RC plane!? I used to tune Kawi motocross bikes with 80 cc'rs. Those things would spit me off the back if I weren't paying attention! Gonna build the tanker for midair refueling too?
    Crazy SOB!!!
    laugh.gif
     
    Re: My weekend project. . .(not gun related)

    80cc is small. Most of my stuff is 100cc or larger. My big Sukoi is scheduled for this 260cc 7cylinder radial!

    If my twin works I may take a stab at making this too. I'll have to get my heat treat furnace figured out before though.



    7cyl radial

     
    Re: My weekend project. . .(not gun related)

    Chad,
    As far as fuel injection,and depending on how the intake system is run on those engines,you might want to look into a Kinsler mechanical type system.that might be the way to go in terms of $$ and reliability.
     
    Re: My weekend project. . .(not gun related)

    I've got a reed valve to install yet at the intake bell leading into the crankcase. A single "slider" throttle body should do the trick. I don't care about an idle circuit. These things start and run WOT from beginning to end. Once out of fuel you land "dead stick" and glide it in. You'd never get it back on the ground again even at idle. The airframes are that clean. They'll ground effect 1000' almost as it is. Just a matter of timing the prop to stop horizontal on the compression stroke so that you don't nick it during touch down.

    I'd like to run a single injector in the crankcase to wet the lower end (remember, it's a 2 cycle) and two additional injectors up in each head.

    The trick is delivery. 35 G's in a corner will lean one of these out in a hurry. A single ounce of fuel suddenly weighs 2.2lbs at that kind of load. It'll take one pissed off pump to keep the engine wet. If I go lean, I'm double phucked. Bad enough to lose power. I'm losing lubrication to boot!

    Unacceptable so I'll have some figuring to do.

    I'd like an in tank electric fuel pump with a return. Problem is I want to run a bladder style tank so I can pull a vacuum on the entire system prior to filling. This way I have no air that could also cause a lean condition. I do this on my other smaller racers. It's worth 200rpm on some as it ensures clean, consistent fuel delivery.

    It'll take some fiddlin but I think I can sort it out. I may end up robbing some stuff from Kinsler or Enderle. I had a Bug catcher on my 69 442 that I built years ago. (decades now. . .
    smile.gif
    )

    For now I just want to see the bugger assembled and making good compression on the stand. Hope to have it running by fall. That'll give me all winter to sort out the fuel issue.

    I still have to build the plane too. The airframe hasn't been touched yet. Lots to do!

    I'm going home!

    C.
     
    Re: My weekend project. . .(not gun related)

    Chad be careful pulling a vacuum on the bladder. They can't take very much positive pressure 1/4-1/2 psi for actual aircraft bladders. Negative pressure will tear it from it's mounts. Are you going to lace it in or how are you going to attach it to the airframe.

    An eaiser solution to ridding the system of air is to make a sort of pop off valve to allow the bladder to fill to the top. Make sure the bladder is vented to atmosphere or better yet, use a pressure regulator (or even a ram air system since it has no moving parts)to input 1/2 psi positive air pressure to the fuel system to ensure feed to the pump.

    To keep the pump wet, build a sump box with simple check valves. use a dual impeller pump so it can feed inverted.
     
    Re: My weekend project. . .(not gun related)

    Chad - look into a very "slight" fuel injection system called "electrojet".

    It is a VERY basic, and lightweight system intended to do exactly what you need. Inexpensive as well.

    I don't know if they are set up for "retail" type business, but give them a call and they'll be able to get you what you need.

    Definitely skip carburation for that project.
     
    Re: My weekend project. . .(not gun related)

    Bladder tanks for rc are pretty tough. Look up "Tettra tanks" and you'll see what I mean.

    I will definetely eyeball the efi setup you mentioned. That'd be sweet!

    Thanks guys.

    C.
     
    Re: My weekend project. . .(not gun related)

    Chad, if you end up pulling too much hair out getting the crank to oil (and I can see it being a pain in a flat twin) you might go the way of ski-doo and use a sealed bearing and isoflex grease. We have made small holes in the crank side seal and added a zirk to force grease through on apps that have poor oil delivery characteristics.

    I just went through a hm-50 morini engine this weekend myself.
     
    Re: My weekend project. . .(not gun related)

    Chad, this is about the coolest thing ive seen yet. thanks for posting, this is BadAss!

    -Paulus
     
    Re: My weekend project. . .(not gun related)

    That thing is going to rip!

    Have you thought about returnless fuel system with a swirl pot on a pivot in the tank?
     
    Re: My weekend project. . .(not gun related)

    So how fast do these go out of sight? Awful hard to drive something you cant see, couldnt imagine how fun it would be to fly something you cant see, most likely into earth
    smile.gif
     
    Re: My weekend project. . .(not gun related)

    You can get small really quick. Stoopid quick. Knowing your orientation is vital. Gotta fly ahead of the plane. Otherwise it flys you!

    Fun stuff. Humbling too.

    C.
     
    Re: My weekend project. . .(not gun related)

    I say a mini 17 HMR gatling gun installed and fly it over a few prairie dog towns...

    Could you imagine the rounds per minute that thing would spit out.

    You should build yourself an A-10 and do that wooo hooo!!
     
    Re: My weekend project. . .(not gun related)

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike Casselton</div><div class="ubbcode-body">I say a mini 17 HMR gatling gun installed and fly it over a few prairie dog towns...

    Could you imagine the rounds per minute that thing would spit out.

    You should build yourself an A-10 and do that wooo hooo!! </div></div>


    I tinker with these as an escape from the gun world. It's my alternative to the crack pipe. Never mind that what your suggesting is a great way to end up biting pillows for cigarettes at the state "Bed and Breakfast."
    smile.gif
     
    Re: My weekend project. . .(not gun related)

    Been to his shop. One corner has some interesting, ahhhh, piles of balsa and aluminum....
    Reminds me of an abstract art display!

    N
     
    Re: My weekend project. . .(not gun related)

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: N.Allen</div><div class="ubbcode-body">Been to his shop. One corner has some interesting, ahhhh, piles of balsa and aluminum....
    Reminds me of an abstract art display!

    N </div></div>

    I hate you Neil.

    Hate you. . .
    smile.gif
     
    Re: My weekend project. . .(not gun related)

    Chad,
    I fly a 50cc gas 2stroke Yak54, always wanted to try out a shoestring racer. Fast is always fun.

    I've pondered tinkering with foam core composites to make airframe and riflestocks with. Have you ever tinkered with this sort of thing?
     
    Re: My weekend project. . .(not gun related)

    Cool! I've got a 100cc extra and am fixiin to build a new edge540.

    I've not messed w/ a scratch build yet. Someday hope to.

    Since your in CO I invite you to come up to our Huckfest in June.

    Good times!
     
    Re: My weekend project. . .(not gun related)

    "Biting pillows for cigarettes" that there is some funny shit! ! !
     
    Re: My weekend project. . .(not gun related)

    Chad make an engine like this radial. Hands down, best sounding RC engine Moki. Other then turbine:)

    <object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/T7YOdY-8o8E&feature=related"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/T7YOdY-8o8E&feature=related" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>
     
    Re: My weekend project. . .(not gun related)

    Radials are nice/cool, but they aren't the engine of choice for racing and/or 3D flying. Good for scale stuff for sure.

    I've got a 43% all composite Sukoi that's tailor made for a radial. I'm prolly going to run a 220cc 4cylinder 2s boxer as it makes more power w/half the weight.

    Wing loading is very important with any plane. Especially 3D.

    C.
     
    Re: My weekend project. . .(not gun related)

    It's near impossible to have fuel feed problems with electric. Electricity doesn't care about G's.

    Since you're already building an engine from scratch, how about considering a hybrid powerplant?

    Use the engine to charge onboard Lithium Ion batteries, and run the actual propulsion motor electrically off them. The electric power source smooths out any power surges due to fuel feed and gravity issues. Start with a full charge and use the onboard gas engine to keep the charge up.

    What works for fuel economy elsewhere should work as well for model aviation. A fully charged battery shouldn't weight much (any?) more than a dead battery. Heckuva way to cut fuel consumption and fuel weight overhead. Might actually weigh less in the overall long run.

    For another thing, the engine, battery, fuel, and generator could be mounted at/near the center of mass. Simplifies some aspects of aircraft performance and/or design.

    Me; I'd mount the engine, fuel, and generator in a pod, to make access (or even swap) easier.

    Also, multiple smaller pods could power a single electric motor, and vice versa.

    This could get <span style="font-style: italic">really</span> interesting...

    Greg
     
    Re: My weekend project. . .(not gun related)

    Battery power has been tried. Great for burst speeds. Sustained is another matter. Discharge rates, amp draw, wattage all leads to an overheated parts. The speed controller would fry too.

    Hybrid. Battery, speed controller, motor, charger device, generator, engine, fuel, and the system to run all of it.

    Heavy. . .

    Charge rates vs discharge rates doesn't make it very practical for a racer.

    Just sayin. Fun to ponder though.

    C.
     
    Re: My weekend project. . .(not gun related)

    As much as I like electric motors (spent the last five years designs brushless DC motors and controllers), something like a hybrid powertrain is going to be far too heavy for an aircraft. Save the batteries and motors for stuff with wheels, where the extra poundage is less problematic and where the proportion of recoverable vs. irrecoverable losses is more advantageous for energy recovery mechanisms.

    Chad,

    Building your own engine is a hell of an undertaking, even for someone with your background - I salute the effort!
     
    Re: My weekend project. . .(not gun related)

    Just ran into this thread. That's a very cool project.
    I'm rather envious of your skill if you are preparing to pylon race. All I fly is big, and slow. Scale fast racers are something else, so are guys that can manage them.
    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: StanwoodSpartan</div><div class="ubbcode-body">So what happens when you crash it?</div></div>
    At the schoolhouse we had a Hobbico 60 named "Frankenplane" made up of the salvaged pieces of trainers crashed by students, new balsa, monokote, and hope. It didn't fly straight, could never get the bloody thing to balance front to back or side to side, and with the engine at anything below half throttle it did it's best impression of a brick.
    When you crash a plane you cry a little...but don't ever reuse the parts: they are cursed. Ok, maybe not never reuse them. They are still cursed.
     
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