Tommy Styrvoky

http://tommystyrvoky.blogspot.com/2016/06/m18-hellcat-tank-destroyer.html blog post with more information.

I would have liked to have the turret traverse slower, but because of space constraints, I don't see any other possible solutions. I attempted to limit the maximum value of the turret traverse m motor to 75% power, but it just stalled out the motor. For the road wheels the 8z gears wouldn't have worked, as they are too small to act as return rollers on the tracks, and the teeth don't mesh with the tracks.

I just need to get another Sbrick, for my next model... I wonder how it works connecting 2 Sbricks to a single device, as my current device seems to work fine, but occasionally the Sbrick will disconnect.

Yeah, It's basically a simple torsion bar suspension, but it mimics the actual design, as the swing arms are offset.

Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr With all of the posts about the new Porsche set, this vehicle would be considered the Porsche or supercar of tanks (it's a tank destroyer), this vehicle was the fastest armored vehicle used by the Allies in WWII. It can travel at 55 mph (88 kph)... now that's not some lightweight sports car that packs a 1000 hp engine, this is a 19.5 ton AFV with a 9 cylinder 400 hp radial aircraft engine... and a high velocity 76mm gun. This impressive weapon allowed the Allies to combat the larger and later war German vehicles such as the Tiger II and Panther. It was known to be the most effective Allied tank destroyer fielded, with higher kill to loss ratios than other Allied tank destroyers. With my model I attempted to copy the drive train and focus on the aesthetics of the vehicle. The most challenging parts of the model would be the upper glacis (topmost armored plate in the front of the vehicle), as where this part met with the "cheeks" above the sponsons. I think a brick solution would have worked here, but I lacked the pieces to build it and all of the available parts wouldn't have been steep enough to work. The open topped turret was also a challenge, as everyone who builds with lego will know round shapes aren't easy. I decided to omit some features on the turret, as they didn't look correct and they effected the smoothness of the turret. The open top allowed me to use an interesting compact turret traverse/gun elevation unit that is rather compact and functions decently (I would like to add more reduction to the traversing gears). This was difficult to mount into the hull, as it is already packed with full-length torsion bars, the torsion bars are 10 studs long, this allows them to be softer for the light model. Overall I am pleased with the amount of SNOT work on the hull and turret. I think I replicated the model to the best of my abilities, though I wish more detail could have been added to the turret, as the massive breech guard limited the gun elevation, and took up lots of space. I also compared the model to the blueprints, and it seems to be mostly faithful to the real counterpart. The most impressive part about this model is the size, I was able to put most of the functions of some of my larger tanks into a footprint smaller than a 32x16 baseplate. I wish Lego made parts for radial engines, as it is very difficult to build a functioning one at such a small scale, as I wished I could have included that in the model too, The only case where I was able to mount one was in my M6 heavy tank. Another interesting engine that would be very difficult to replicate is the Chrysler multi-bank, a 30 cylinder engine mounted in later versions of the Sherman. I would like to sometime replicate that and put it in a M4A3E8 "Fury" tank. I had a lot of fun with the editing, my new photography backdrop makes it easy to clean up photos, just by adjusting the RAW exposure, you can get a pure white. It also rained today, so no outdoors footage, but I had some fun with photographing the model in puddles, as there are interesting reflections. Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr A comparison with blueprints, there are some minor perspective differences, but it is relatively close for Lego. Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr an underside shot... not too much here to see, but you can see how the swing arms alternate between half-stud offset, and full stud offset, this allows for a 5.5 stud space between road wheels. Also note how the left side torsion bar is leading in front of the right side. Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr A couple renders of the traverse/elevation mechanism, instructions for that will be comming soon. Lego M18 Hellcat turret traverse/gun elevation mechanism. by Tommy Styrvoky, on Flickr Lego M18 Hellcat turret traverse/gun elevation mechanism. by Tommy Styrvoky, on Flickr Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr The unit markings for the Hellcat are from "Black cat" both of my cats were wandering around when I was filming. Lego M18 Hellcat Tank Destroyer (Sbrick by Tommy Styrvoky, on Flickr IMG_1591 by Tommy Styrvoky, on Flickr Turret details IMG_1597 by Tommy Styrvoky, on Flickr IMG_1601 by Tommy Styrvoky, on Flickr IMG_1602 by Tommy Styrvoky, on Flickr Suspension Lego M18 Hellcat suspension by Tommy Styrvoky, on Flickr

Great job with the shape and functions, could I see an underside shot?

Great job replicating it, I have seen one in real life, and it is probably one of my favorite locomotives. Have you tried testing how powerful it is at pulling cars/ weight?

looks great, how much space is taken up in the front for the moved shifting mechanism?

it says it should have a Technic feel to it... all studded models with lots of functions. I don't think it says anything about when the model was built, as that could reject it, as they are both about a year old. I think this would be enough to reject the model "Your entry must clearly represent Porsche brand design" ... or the greedy Ferdinand Porsche of WWII, I don't think that is the porsche design, I think they must have put these vehicles in their past.

I thought about that or a maus... Though I don't think the designers would like it, Though I could enter my Tiger P or Elefant into the contest as a joke. But it is my dream Porsche... Who wants some silly run of the mill supercar, when you can have a one of a kind 188 ton monster that has worse fuel efficiency(7.2 gallons per mile) than a diesel-electric locomotive.

Well I have a few ideas for a model. I wonder if it's specific to any previous or current porsche model?

I think it would be possible with the current gearbox to toggle a changeover catch like you mentioned.

This is more of a semi-solid axle with differential or maybe better used as a friction induced power transfer mechanism( say you have two output shafts, one is the differential side, and the other is mounted on the ratchet, when the ratchet is overcome, the power gets transferred to the differential.)A real LSD will only slip on one side for some duration, then transfer power from the slipping side, hence the term limited slip. As with your version, when the differential starts slipping, there isn't anything to stop it from slipping or allocate some power from the slipping side to the immobile side. While with the ratchet in your version makes the whole axle behave like a solid axle without a differential, but when slip occurs it will behave like a traditional open differential.

Well I fixed the flaw I missed yesterday when I was configuring the suspension to fit around the bodywork... It was late at night (actually morning). It now has proper caster angle, and I removed the points where it had collision issues. Now I noticed something else, the shock absorber sometimes will bend, this is because of the hard suspension. I think the front suspension needs to be replaced with soft suspension, and it functions fine. I think this will work with the current model, as the shock absorber is in a more vertical position, so it has more leverage on the lower arm. So to fix this problem, either a new upper spring mount, or softer springs used. Though I am unsure if soft springs can support the model? I took a look at Appie's rear steering design, and I think I see some possible methods of moving the spring mount of my current macpherson suspension to function with the rear wheel hubs and allow for a driven axle. I will see about configuring it around the rear axle. Another though for the rear suspension, is a method of switching between crab steering and traditional steering, as the rear car uses this at different speeds. I was thinking something to the main shifting console, but the middle position= no rear wheel steering. Though any good thoughts for where to mount the changeover catch for toggling it? I was thinking making a linkage that would route up to the center console, and maybe a switch could be mounted there. LDD file http://www.bricksafe...cpherson V2.lxf GT3 RS macpherson V2.lxf by Tommy Styrvoky, on Flickr GT3 RS macpherson.lxf by Tommy Styrvoky, on Flickr GT3 RS macpherson colored.lxf by Tommy Styrvoky, on Flickr

I think I am nearing a finished design for the Macpherson suspension for the front. There is only one area that may cause issues with the trunk structure, but everything should fit on the stock body, and work with the "marriage" of the body and chassis. I think another issue that could arise with the current shock mounts is collisions with the upper part of the shock and the shock mount, say if the model's wheels are being turned, and the suspension gets fully depressed, but I think this is unlikely to happen. If there is issues with the trunk colliding with the upper shock mount, I will need to flip it around. Could someone please test the clearance between the trunk and the front? Or a picture from the side of the model, near the wheel arches looking at the space between the suspension and the front of the trunk would be nice, as I lack the parts to build a mockup of it. It is also a rather easy drop in part, you just have to remove the upper A arms of the suspension, and the pieces connecting the upper and lower arms, and a couple parts that are in the center. A few of the parts get reused in the suspension too. LDD file for just the suspension http://www.bricksafe... macpherson.lxf Edit... I accidently changed this version to negitive caster angle.... well I guess it isn't a final version yet. I will fix it tomorrow. Lego GT3 RS macpherson.lxf by Tommy Styrvoky, on Flickr Lego GT3 RS GT3 RS macpherson strut.lxf by Tommy Styrvoky, on Flickr Lego GT3 RS macpherson colored.lxf by Tommy Styrvoky, on Flickr

I don't think it should cause any problems to place the parts in either orientation, CV= Constant velocity joint, so it is designed to function correctly, until it reaches it's maximum travel, then it can have problems locking. With the error in the instructions, it will align itself when you shift the gearbox.

I was thinking about replacing the shifting mechanism with something similar to Piterx's design,as moving the entire shifting mechanism would work, but it's rather large, and to route the linkages may take up needed space.

my guess is that there will be eventually a master set of instructions containing most of the mods, possibly like the ultimate 42009.

could i have a file of the basic bodywork? As I have. A couple thoughts for tweaking it around the bodywork.

More progress on the front suspension, and Ackerman Geometry. The front suspension is nearly complete, I know there will have to be modifications to the trunk interior, in order to mount the bodywork on the model, but it isn't included in the LDD file. I have made a mockup of a strut, and the suspension seems to work fine with soft and hard springs, though for hard springs It may need more reinforcement. Don't forget to mount the 8z gears on the 2L axles, otherwise the suspension will have lots of slack. These parts are in dark purple. A small test of the geometry( it's close, but maybe off by half a stud.) I think the smaller steering rack will decrease the turning radius, but it should be similar to the original kit's, as Jim mentioned in his review that the 24 hour car had the approximately the same wheel radius. If only lego produced an 11 stud wide rack, a custom brick built rack would work better, but I have to mess around with that in real life. Also the mounts for the brake calipers need to be reaffixed to the new suspension struts. updated file http://www.bricksafe...son strut 2.lxf Color coding -Green= Behind axle steering/Ackerman geometry - Bright purple= Macpherson strut suspension - Bright reddish violet= parts need to be mounted together. 42056_Ackerman Geometry by Tommy Styrvoky, on Flickr 42056_macpherson strut by Tommy Styrvoky, on Flickr 42056_macpherson strut by Tommy Styrvoky, on Flickr Next to work on the shifting drum, I am almost questioning if someone should start on replacing the awfully designed gearbox with a better functioning one. as that seems to be one of the major drawbacks of the model. I think it could work with a six speed transmission, and a six position shifting drum, though I will attempt to make solutions for both.

I don't think disc brakes will be possible for the front axle,but the back would work, because of the wheel hubs. it wasn't centered over the shock absorber, and I wanted to make my own design. I also noticed play when the upper mount when it isn't supported.

it's missing a part, a pin/axle cross block with a 1/2 stud long technic pin. This eliminates the movement you speak of, and the spring should be moved to the next axle over(the purpose of these parts is to sandwich the springs in place). I forgot to mention the 8z gear that goes on the 2 stud long pink axle, that eliminates a lot of play in the suspension. That's why I color coded it and the gear pink.I will just post the ldd file later tonight,I want to change the upper mount structure, as it interferes with the bodywork.

Here's a couple interesting thoughts for modifications. I think it would be possible to mount functional brake and accelerator pedals. I think there could be technic rubber parts used to apply pressure on thr rims of the tires, and be toggled by either string or linkages.For the accelerator, I think it would be possible to mount a 7v Lipo battery box in the front trunk, and connect the adjustment knob to a linkage to the pedal. Then connect a L motor to the engine. Though before this can be done, thr paddle shifter has to be compacted, I do have a couple different solutions to solve that problem.

I improved the suspension, and compacted it slightly. Now the shock absorbers can use their full travel length. It was rather easy to mount the steering rack behind the axle, and only required the addition of a couple new parts, I need to determine the correct length for the new steering arms, so it can have proper geometry. I will try to keep parts color coded, for ease of assembling all of the mods into one file, so eventually this can be exported into ldraw format for a master set of instructions. lego Porsche GT3 RS updated Macpherson suspension and behind the axle steering by Tommy Styrvoky, on Flickr lego Porsche GT3 RS updated Macpherson suspension and behind the axle steering by Tommy Styrvoky, on Flickr

Here's my first mod to the suspension, it now features kingpin inclination, positive caster angle, and macpherson strut suspension. I tested the shock absorber, and how it is anchored. It seems to be robust enough, but it only has about 1 stud of suspension travel... though this is a sports car. one way to increase travel would be to remove one of the wheels locking the shock absorbers in place, but I think that would increase the amount of play in the suspension's rigidity.I would like to refine the upper shock mount,as it isn't too durable. I think I may also change the layout of the trunk,as it seems more spacious in the real car. The suspension arm couldn't be mounted in LDD, so I placed it off to the side. Lego Porsche GT3 RS macpherson strut suspension by Tommy Styrvoky, on Flickr Lego Porsche GT3 RS macpherson strut suspension by Tommy Styrvoky, on Flickr LDD file http://www.bricksafe...erson strut.lxf I think to add Ackerman geometry, would it be easier to move the steering rack behind the axle, as it requires the steering arms to be splayed out to achieve proper geometry. So maybe the usage of the 7 stud wide rack would allow for modification of the current steering arms. Time to start on that and the paddle shifters.