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Luftwagen (formerly the Karma Bug)


David G.

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I want to see if I can knock another one out before the end of the year.

I bought this pile of parts years ago at the Desert Scale Classic for a couple of dollars. One sleepless night about a decade ago, I pulled this mess out with the intent of sorting and cataloging it all. As one might imagine, I ended up actually working on it. That's when the name Karma Bug came into my mind. There's no logical reason for the name, it's just what I started calling it in my mind.

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This is the original kit as it was released back in 1987. Ah the eighties... Let's see if I can save this kit from its past.

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With some wheels from the parts box, I now have something to work with.
 
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Looks like a previous owner wanted to make poor little car a flip-nose custom. *sigh*
 
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Yup, I'm goin' there! I'll need to lift the tail a little... or shorten the prop.
 
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As always, thanks for taking the time to look and please feel free to post a comment, critique or suggestion.
David G.
 
 
 
Edited by David G.
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Do away with the flipnose, add the nacelle and prop up front, proper. (Parachute out back.) Raise the body til it fits, gasser style! Hang drop tanks with inset steps under the rocker panels. Rivets galore!!  Custom fender skirts for the rear to mimic Stuka landing gear spats.

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5 hours ago, bisc63 said:

Do away with the flipnose, add the nacelle and prop up front, proper. (Parachute out back.) Raise the body til it fits, gasser style! Hang drop tanks with inset steps under the rocker panels. Rivets galore!!  Custom fender skirts for the rear to mimic Stuka landing gear spats.

That actually sounds like a good plan to me, although, I think I may have mental problems. Lol.

Later-

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20 hours ago, bisc63 said:

Do away with the flipnose, add the nacelle and prop up front, proper. (Parachute out back.) Raise the body til it fits, gasser style! Hang drop tanks with inset steps under the rocker panels. Rivets galore!!  Custom fender skirts for the rear to mimic Stuka landing gear spats.

Rusty and Tom, thanks for the input, lots of good ideas there. I do want to keep the engine in the back, sort of a pusher style fan boat- It is a VW after all! 

There is no flipnose. When the previous owner cut the front off he salvaged the hood and fenders but there are no side panels left. I've spent a fair amount of time thinking of how to piece it all back together and came to the conclusion that if I tried to recreate a stock configuration it would just end up looking like a poor restoration attempt. That's why I decided to do a slap-dash custom job. 

Karma_Bug08.thumb.jpg.a13d9a1c735c3f9853ed20eb36adcad1.jpg

As far as the nacelle idea, I do have some airplaney bits that I'm trying to piece together for the front but blending the shapes and surfaces is proving to be a challenge so I may just go with panels and rivets- raw metal, of course!

Whichever way I go, it will certainly have a Mad Max wasteland feel to it.

Thank you for sharing your thoughts, I now have some more options to consider.

David G.

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Time for another update. I still think I can finish this one before year's end.

On my wife's recommendation, I cut the airplane engine deeper into the chassis to reduce some of the overhang. This will also allow me to add some visual interest to the interior with additional machinery.

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I'm still not sure what I'm going to do with the front end.

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But at least I got the ride height in the back where I want it. So... the car has been "stanced" as the saying goes. I plan to adjust any other clearance issues as I mount the engine.Karma_Bug07.thumb.jpg.cca0d98e2d5164455f3d3208d5fe57bb.jpg

 
As always, thanks for taking the time to look and please feel free to comment.
David G.
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33 minutes ago, Snake45 said:

You had me until you stuck the airplane nose out the rear. 

If you're going to do that, you might want to reverse the prop so at least the blades are propelling it in a forward direction. :unsure:

   I was just going to ask if that was a vehicle

meant to go only backwards!?!  LOL!!!

  But it's pretty cool so far! 

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1 hour ago, espo said:

Enjoying watching this build. The rear mounted engine is interesting, I'd like to have a 1:1 on the back of my car, no more tailgaters.  

Thanks David. It would definitely enforce the three second rule.

34 minutes ago, Snake45 said:

You had me until you stuck the airplane nose out the rear. 

If you're going to do that, you might want to reverse the prop so at least the blades are propelling it in a forward direction. :unsure:

 

1 minute ago, mod3l Lover said:

   I was just going to ask if that was a vehicle

meant to go only backwards!?!  LOL!!!

  But it's pretty cool so far! 

Thanks guys, I actually imagine that the engine is operating in reverse direction. I mean why not? I'm mounting a plastic 1:48 scale airplane engine in a 1:25 scale plastic automobile. I think that reality has long since been thrown out the window on this one. I usually do try for at least a semi-plausible explanation whenever I can though. 

I am working on a reversed air cooling intake to account for the lack of air being rammed into the engine under the conventional operating scheme.

And to quote a very wise man:  Remember, to a real modeler, kit instructions are just Somebody Else's Opinion. 

Thanks for taking the time to share your thoughts. To know that there are folks paying that much attention to what I do makes me happy.

Thanks 

David G.

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9 minutes ago, David G. said:

Thanks guys, I actually imagine that the engine is operating in reverse direction. I mean why not?

I don't have a problem with that, we can "assume" it rotates whatever direction you want. But the prop blades have a definite front side and back side to do their job, and it won't work--at least, not nearly as well--if it's mounted backwards. Just turn the prop around so it's facing the correct way. B)

Edited by Snake45
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26 minutes ago, Snake45 said:

I don't have a problem with that, we can "assume" it rotates whatever direction you want. But the prop blades have a definite front side and back side to do their job, and it won't work--at least, not nearly as well--if it's mounted backwards. Just turn the prop around so it's facing the correct way. B)

My apologies but my knowledge of basic aeronautical engineering is apparently lacking. Looking at the prop now, I think I can see what you're saying. 

The way that the piece is structured, each of the propeller blades mounts individually to the central hub. If I had realized this before I assembled it, I may have been able to flip each of the blades individually and mounted them that way. The way the assembly is structured, it can't just be flipped over and mounted- at least not easily. Since I've already glued the assembly together I'm concerned that I may damage or destroy the blades if I try to disassemble it now.

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I may be able to find a second prop assembly in the parts box and see if I can make a go of it but if not I may have to resign myself to living with the error.

On the bright side, I did get some painting done today! :D

Thanks again Snake for taking the time to comment, I do appreciate it.

David G.

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In the decade I've been a member of this community I have learned a tremendous amount of information relating not only to, most obviously, model cars and model building in general but also automotive history and engineering, physics, a bit of chemistry and even marketing.  To that list I can now add aeronautical engineering.

Though it seems obvious now, the concept that a propeller blade would have a specific directional structure had not occurred to me. My thought was if the direction of operation were reversed, the action, force and work energy would also reverse. After a little independent study on the physics and operation of aircraft propellers I learned that in prototypical operation most modern propellers have a variable pitch adjustment which essentially allows them to reverse operational direction while maintaining the same direction of rotation. This allows for pushing air forward of the aircraft, acting as a type of brake, rather than pulling it toward the aircraft to cause acceleration and create lift.

So what does all this mean? Essentially nothing aside from giving me a somewhat rational explanation for how this whole irrational combination might reasonably function. Q: "So if the propeller turns in reverse, how do they get forward motion?" A: "They vary the pitch."  :D I almost forgot to mention that I've worked in a transfer case between the rotary engine and the VW trans-axle to drive the road wheels.

Besides, the way the propeller blades are formed to accommodate the shroud, I don't believe that simply flipping them over and mounting them would work without significant alteration or complete re-fabrication. Either it's a bit more work than I want to do for this goofy mash-up.

Karma_Bug20.jpg

So, after a bit of thought, I've decided that I can live with the prop the way it is.

Now, on with the show!

These air scoops are among the custom bits provided in the kit. Though I don't recall ever seeing an old Bug with anything like in place, I plan to use them for their intended purpose.

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In its usual configuration, a radial engine of this type is cooled mainly with the air rammed through it by the prop. Since this engine is in the rear and running the prop as a pusher instead of a tractor, the prop would have to pull air through the engine for cooling. All that air would have to come from somewhere and I think the scoops would help with that.

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The air collector will be attached via tubes to the window scoops. The box will house the "avionics controls".

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As always, thanks for taking the time to look and please feel free to comment.

David G.

 

Edited by David G.
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All trimming does is tend the prop towards a stall. It never gives reverse thrust. So your Bug would only ever be able to go backwards unless the prop is reversed - twist each blade 180 degrees'll do it. Like Snake said...

Totally worth it 'cos it looks great. I like the scoops.

-Don.

 

Edited by DonW
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20 hours ago, DonW said:

All trimming does is tend the prop towards a stall. It never gives reverse thrust. So your Bug would only ever be able to go backwards unless the prop is reversed - twist each blade 180 degrees'll do it. Like Snake said...

Totally worth it 'cos it looks great. I like the scoops.

-Don.

 

Thanks for the comment Don, I'm glad you like the scoops.

The prop on the other hand is quite securely glued together and I believe that trying to pull it apart to rearrange the blades would probably destroy it. Unless I can find another one I'll probably just have to live with it the way it is.

Believe me, this isn't a matter of trying to convince me to do the right thing, it's more a matter of me trying to justify, in my own mind, the error I've made. If switching the blades was matter of just deciding to do it, I would have done it by now. 

I'm still looking for another prop. If I can find one I'll correct the error. If I can't, I'll just have to live with the story I've created or abandon the project all together.

Thanks,

David G.

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Hello everybody, it's time for another update.

One of the big problems I've had working with this project is what to do about the front end. I think I've found the solution to that problem. This is the nose piece from an old 1937 Cord model kit.

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Just on its own, the Cord hood and grille remind me of the eagles on the Chrysler Building. That's not surprising, they're both from the Art Deco period.

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It may seem like an odd combination but I don't think it is horrible. The original Cord 810 body did have a somewhat similar shape to the Beetle.
 
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Obviously this is going to take a bit of cutting and pasting but the fit isn't that far off. I think I can make it work.
 
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I'll have to come up with a way to address the area below the grille... some sort of a chin spoiler.
 
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As always, thanks for taking the time to look and please feel free to comment.
David G
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I kind of like the Cord front end idea. The only constructive suggestion I could offer would be to level the body and the front end. The body appears to be going up hill and the Cord portion of the front end is going down hill much like a normal VW drop off. Should you want to just level the body in relation to the chassis then the front end would really drop off.  

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35 minutes ago, espo said:

I kind of like the Cord front end idea. The only constructive suggestion I could offer would be to level the body and the front end. The body appears to be going up hill and the Cord portion of the front end is going down hill much like a normal VW drop off. Should you want to just level the body in relation to the chassis then the front end would really drop off.  

Thank you David. I've already trimmed the bottom apron on the side pieces of the Cord nose and a bit of the pointed angle on the top rear edge and it is sitting level with the body and chassis now. What I'm up against now is widening the back of the hood by three or four mm. I'm considering cutting the hood down the center and splicing in a long wedge of styrene to widen it. Or I could make twin cuts, each closer to the outside shoulder of the hood and splice a wedge in each cut.

Of course all of that depends on how flexible the old styrene is from the Cord kit ?

I am certainly open to suggestions.

David G.

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3 minutes ago, David G. said:

Thank you David. I've already trimmed the bottom apron on the side pieces of the Cord nose and a bit of the pointed angle on the top rear edge and it is sitting level with the body and chassis now. What I'm up against now is widening the back of the hood by three or four mm. I'm considering cutting the hood down the center and splicing in a long wedge of styrene to widen it. Or I could make twin cuts, each closer to the outside shoulder of the hood and splice a wedge in each cut.

Of course all of that depends on how flexible the old styrene is from the Cord kit ?

I am certainly open to suggestions.

David G.

The center cut would have been my suggestion. As you pointed out the flexibility of the old Cord plastic could be an issue, The area between the Windshield and the back edge of the Cord hood lineup well now. While the center cut maybe the easiest to do the problems might just be at the front when you spread the nose, again the flexibility of the old plastic and what will happen with how the front grill bars line up ? The idea of cutting and adding a wedge on either side of the top of the hood might be the best way to go to minimize the grill distortion, also small relief cuts on the inside of the corners would minimize the stress on the front end. The backside could be reinforced with some Styrene angle pieces. Depending on the size of the wedge cuts you would want to reinforce them also. Bits of flat stock or even use Styrene T molding as this would offer support on both sides of the cuts. Hope this will be of some help to you. I'm enjoying watching this build. 

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1 hour ago, espo said:

The center cut would have been my suggestion. As you pointed out the flexibility of the old Cord plastic could be an issue, The area between the Windshield and the back edge of the Cord hood lineup well now. While the center cut maybe the easiest to do the problems might just be at the front when you spread the nose, again the flexibility of the old plastic and what will happen with how the front grill bars line up ? The idea of cutting and adding a wedge on either side of the top of the hood might be the best way to go to minimize the grill distortion, also small relief cuts on the inside of the corners would minimize the stress on the front end. The backside could be reinforced with some Styrene angle pieces. Depending on the size of the wedge cuts you would want to reinforce them also. Bits of flat stock or even use Styrene T molding as this would offer support on both sides of the cuts. Hope this will be of some help to you. I'm enjoying watching this build. 

Thanks for your insight David, I have a few more options to consider now.

David G.

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