Oh, it makes me sad a little. I modeled three types of Ripsaw with swappable parts. Testing those in MMT is great and I have a lot of fun! Admittedly, I still can not connect properly the spring suspension and the arms, but the wheels and tracks work great. And honestly I had hope that someone would help me with this here 
Does this mean I will not be able to build ripsaw with the new MMT in the future? I am interested in hovercraft and in those aeroski that I would like to adapt to snowbikes. What else will be removed from MMT?Thank you for your answer.
You can build any kind of tracked vehicles, including half-tracks, using new classes. Look at T-26 as an example, it’s called “LightTankTraceWheelsWithAnimBPPrototype“. You can find it in the main level.
There is nothing particularly special about Ripsaw in the level, it uses the same class as M113, just slightly different settings. While T-26 is reworked from the scratch, if you check YouTube videos, featured development is on T-26, not on old system.
Hehe, It looks like there is hope for me 
If I understand it well, it means that I should follow the T-26 build instead of M113 if I want to have Ripsaw even in a better manner. That’s great! Thank you for enlightenment! I’m going to look at this closer tonight
I’m sorry for stupid questions I see T-26 is skeletal mesh. In order to build Ripsaw from T-26, I have to make (rig) skeletal mesh (wheels and suspensions)? Or is a way to build this using my existing static parts?
You can do it using static meshes. Skeletal mesh is better for performance, as not only math used to rotate/move bones is executed faster but you uses less components (derived from scene components) which have effect on performance too.
Great! So I have two options. I can try to do a new suspension rig, or go with static (less efficient) meshes. I watched how the T-26 is rigged and it looks like it is a single bone added to each element at the point of its rotation. Is there something specific that I should keep in mind when rigging? Every tips is gold to me and I will be very grateful for every help. Maybe you know some tutorial on rigging specifically for MMT? Or someone with whom I can contact and ask for help. I can provide parts (I have MMT packed into ZIP with simple Ripsaw ready to share (static meshes-parts with seperate wheels, suspension arms, springs), and I will be happy to share the result. It would be best for me to see an example on how it’s all connected, and be able to build more models based on this pattern. I do not want to build a game (it’s still too much for me), I rather want to focus on building models and testing them (best part) and sharing (free and premium if it 'll be good enough). Thank you for your time!
Rigging for non-organic objects is usually very simple. You create a single bone per part that you want to articulate independently from others. There are no weights involved and all vertices are skinned 100% to appropriate bone.
For example:
Each color represents an independent part. Blue is a “lever” that follows physical wheel of suspension. Red is a cosmetic wheel, it can be set to have exactly the same position as physical wheel or just be placed on the end of the blue “lever”. In later case, it should be a child of the lever, in former case it can be just a child of a root.
Green is a “spring” box and yellow is just a rod that pushes on spring.
If we look at the schematic view:
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Then you can see that mechanically, the end of the lever will move in an arc while looking at “physics” suspension point (pink dot). Physics suspension point is a Hub Location that you get from Suspension Stack component, after each update of suspension calculations. Physics wise, suspension won’t move in an arc but a straight line (just a limitation of how traces work), but for cosmetic purposes it doesn’t really matter. Physics suspension can be just vertical or angled to better match “curve” of the visual suspension, see what works better for you in term of handling and driving. To animate lever, you can use LookAt transformation in the AnimationBP, to make lever point at some arbitrary point in the space, in this case at the point reported by suspension. If wheel is a child of the lever and placed at the end of the lever, it will automatically follow and you only need to change it’s pitch to imitate rolling.
The yellow rod, can be made as a child of the lever too and it’s bone placed somewhere along the lever near the wheel. The green spring box is a child of root. In Animation BP, you can again use LookAt to make green box and yellow rod look at each other. This way they should perfectly align when suspension is going up and down.
The general rule, to avoid issue down the line, is to orient bones and meshes in such a way that X axis of the bone, aligns with forward vector of the model. For example, in case of a lever, dotted line with arrow represents the X axis of the bone and lever would be modeled/positioned in the same way, so that a hub where wheel is installed matches with the arrow.
Thank you very kindly Sir, I appreciate that! I think I understand, at least part of rigging. I understand the diagram on the prepared picture (you are great), probably it will be harder to connect it all. For now I have started preliminary work on Hovercraft (sport), but in between time I will try to do as you said. Have a nice day Sir!
Don’t need to go for the full complex setup at first. Do it step by step, start with a simpler case, like just a box with some wheels on levers and then add details as you learn more.
Exactly, you are right. Well, I’m not giving up and I’m going to try slowly. Thanks!
Update:
This feature was in MMT for awhile:
It was disabled by default and apparently Gaussian blur shaders got broken after one of the UE4 updates. Not its fixed and working again. I’ll keep it enabled.
Hi Bored Engineer! Thank you for the update! I must admit honestly that I have worked for two more days, but I have to return to work on another project to maintain the continuity without a gap. I failed to connect properly suspension (my Ripsaw jumps here and there ). I understand how it works, but I think I need a lot more time, which I do not have. But that does not mean that I want to give up! I have an idea and I need your blessing and correct me if you do not like something. Who knows maybe it will work.
Idea:
I have a Ripsaw model packed with MMT (4.18) ready (free on Gumroad with 0+ price) to play, share and looking for interest. The model will be free on the same basis as MMT (free to use for educational purpose). 2k pbr maps (BC, ARM, N), 2 UV’s (UVMap, LightUVMap). All parts of the suspension are separate so that someone can figure out how to connect the spring suspension and arm to the wheel and share this knowledge back with us as a downloadable example or good video tutorial. People like me could fully enjoy the Ripsaw ride. I could then focus on improving this example to provide better Ripsaw experience (maybe rigging to try this more performed method in the future), modeling a larger number of exchangeable parts, variants and easily test them with MMT.
If you find a moment, please let me know what you think about it. If you have any objections to this idea, please share it with me. I am open for suggestions.
MMT is free and I want to provide the model on the same license to keep progress on ripsaw in MMT. The main question is whether I can share the link with packed MMT and my model together? This will allow interested parties to quickly take action. Of course, along with a clear description, regarding intellectual property.
Short video on how its look like at the moment
** - **Please read video descriptions to see if it’s correct with you.
Looks like suspension is a bit too strong. But as you are using old physics model, it’s limited as to how much you can tune it. Model looks pretty cool!
It’s fine with me, just don’t forget to include license.txt file with the package. You can add another license file that explains rules of how your Ripsaw model can/can’t be used.
OKey, that’s great, thank you! I will include both license.txt.
Yes suspension are a bit too strong, but its on a fresh MMT (UE4.18) project I just replaced the parts. So all settings are same as original/provided Ripsaw example to have clear start. I think I should update to be on time with MMT ( UE4.19), and I will do it soon. Ones again thank you. Will see what happen If nothing I will try to manage some more time to devote on it. But this mean I will be asking you a lot of questions - we don’t want that, hehe
By new version I mean “tank template” version. Which is called “LightTankTraceWheelsWithAnimBPPrototype”, that’s a current feature complete version with all bells and whistles.
I know it’s a bit off topic but I’m wondering if the air drag formula on the AirDragSimple blueprint could be used on a bullet projectile.
I’m testing and getting a 0.001714 fixed drag multiplier (0.338 surface area, 0.785 drag coef, 1.2922 air density), but then squaring the bullet velocity 83000^2 gives a way to big number to be used.
Yes, it’s applicable to bullets and other ballistic projectiles. Check your units, like velocity should be in meters/second. Default in UE4 is cm/s.
