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View Full Version : Twisted Hobbys Crack Yak EPP Foamy


Madratter
02-11-2012, 11:28 PM
I've gotten permission to create a version of this plane for Realflight (thanks Brad and Chris!). :) I own the plane and I photographed the parts so I could put together top and side views. I really want to do a knock out job on this one.

Madratter
02-13-2012, 12:53 PM
Well, I spent some time yesterday, experimenting with Blender as I was considering using it for the entire build. After doing so, I came to the conclusion I simply do not like the way that Blender deals with the background images. There are many things I like about Blender better, but the inability to actually associate an image with a particular axis and show the images in anything but top, side, or front view is a real hindrance. For example, it makes lining up your top and side views so they are registered perfectly a real problem. There may be ways around this, but I'm not smart enough to have found them.

So, I ended up getting my top and side views imported into Wings3d and ready to go for the start of the actual build.

I'm torn with this because I actually prefer Blender in many ways. I find its interface less clunky (if somewhat more intimidating) and it is certainly more capable (parenting and pivots come immediately to mind).

abaser
02-13-2012, 01:06 PM
2nd post of blender tips thread. There's a link for what you want

Madratter
02-13-2012, 02:49 PM
2nd post of blender tips thread. There's a link for what you want

Perfect. Thanks! :)

flexible
02-13-2012, 03:21 PM
http://www.youtube.com/watch?feature=player_embedded&v=4QMHoCmuiAo

This young man shows great promise.
This plane flies great.

Madratter
02-14-2012, 11:39 AM
http://www.youtube.com/watch?feature=player_embedded&v=4QMHoCmuiAo

This young man shows great promise.
This plane flies great.

He does a great job with it, doesn't he :).

Last night, I was able to get my 3 views into Blender the way I wanted them. The video Andy referenced had some great tips. I like this method a lot, although it is a bit on the complicated side of things.

flexible
02-14-2012, 12:04 PM
Found these picks of the motor they use.

Madratter
02-14-2012, 12:27 PM
Found these picks of the motor they use.

Thanks. I have been trying to figure out whether I'm going to model the motor from scratch, or start with one you have done and kind of morph it into this.

I own the plane, and the version that Twisted Hobbys uses doesn't have the orange lettering around the side, which makes it a good bit easier, since that won't need to be mapped. They also have pre-soldered bullet connectors to the motor and the Esc.

It's a fantastic kit. I really liked the first one I got from them (32" Xtra Slick). But their kits have just kept getting better and better (I own 5). I'm almost finished building this one. (Completely built and flying, I have their Xtra Slick, Crazy 88, and Edge 540). Note that the Edge 540 I built for RF6 is not modeled after their plane. I didn't have a good 3 view of it.

flexible
02-14-2012, 01:57 PM
This is one of my newer motors. The back of the case is the only deference I notice. I can, if you are interested, ether post it as is or change the back of the case, then post it.

Madratter
02-14-2012, 02:28 PM
This is one of my newer motors. The back of the case is the only deference I notice. I can, if you are interested, ether post it as is or change the back of the case, then post it.

That looks really close. You can post as is or changed. I'm the beggar here, but I would like to use it.

jeffpn
02-14-2012, 02:35 PM
If you're interested, in my Skywalker tute, I outline one way to make a motor, if you'd like to take a look. It might get you thinking of a way to model your own. Starts at post #193.
http://www.knifeedge.com/forums/showpost.php?p=208036&postcount=193
You'll find a link to open the thread in the upper right corner.

flexible
02-14-2012, 02:45 PM
I'll tweak the back, then post it.

flexible
02-14-2012, 11:49 PM
New Motor. You can use it without Maping if you wish.

Madratter
02-15-2012, 11:22 AM
New Motor. You can use it without Maping if you wish.

Thanks Flex. Much appreciated. :D

Madratter
02-17-2012, 04:55 PM
Well, the status on this is that I have put together the basic vertical fuselage shape and I have been attempting to cut holes into it. For some reason, this is not going well this time around. I end up with sections that are missing, like the faces are not there. :mad:

The problem shows up in RF6 as well. So I really need to deal with this.

My attempt with an extruded cutout that was more complicated was even worse, but this illustrates the problem with a somewhat simpler shape.

abaser
02-17-2012, 05:21 PM
I see you have stuck with .49. Your only fix that I'm aware of is to manually recreate the faces. To do that, select 4 verts and hit F. 2.6 has this nice bridge function. Select 2 opposing faces, bridge, and it's done. As long as you dont get carried away with modifiers and materials, 2.6 is your better bet. I was leary at first, but love it now.

abaser
02-17-2012, 05:23 PM
Oh ya, anytime you delete a vert, edge, or face, you must recreate the face associated with what you deleted;)

Madratter
02-17-2012, 05:29 PM
Oh ya, anytime you delete a vert, edge, or face, you must recreate the face associated with what you deleted;)

I guess 2.6 it is. I already did a lot of face creation earlier in the build when for some reason, a bunch did not get created properly, and the shading was off as a result. Back at it.

abaser
02-17-2012, 05:43 PM
I think you will be happy with the switch. You have to turn on the bridge command though.. I'll double check, but I think is under preferences> add ons> loop tools. Then it will show up in the tool window (hit T).

Madratter
02-20-2012, 11:20 PM
Well, progress has been limited for various reasons like playing at 4 different services this weekend with my guitar.

I have managed to install Blender 2.6 and I'm starting to get over the hump in terms of the differences (which are significant).

Here is the fuselage section of the plane. Notice the huge side.

bosshawg
02-21-2012, 08:54 AM
Select Object with Scale Not set at 1,press(Ctrl and A)buttons together choose "Scale to ObData".
Objects Not scaled to 1 can have severely distorted UV's and could be the source of your boolean difficulties.
Best Practice is to do all your Scaling in "Edit Mode" NOT in "Object Mode".
Hope this Helps.:)

Madratter
02-21-2012, 11:50 AM
Select Object with Scale Not set at 1,press(Ctrl and A)buttons together choose "Scale to ObData".
Objects Not scaled to 1 can have severely distorted UV's and could be the source of your boolean difficulties.
Best Practice is to do all your Scaling in "Edit Mode" NOT in "Object Mode".
Hope this Helps.:)

Thanks. I appreciate the tip. :)

Madratter
02-21-2012, 11:42 PM
The scaling problem mentioned by bosshawg has been fixed.

I worked on modeling the wing tonight. I have a feeling there is probably a better way to define this sort of shape. I started with a cylinder because I wanted the point in the center since it makes getting all the triangles to stay within the shape easier. At any rate, I still ended up with a little shading weirdness going on in texture mode. It is much better in object mode but there is still a little something that is not quite right.

Madratter
02-23-2012, 11:28 PM
Here is my latest progress. I have brought this into RF6 so I know it will model there.

Madratter
02-24-2012, 10:35 PM
I'm at the point where I want to do my pivot points. I have been driving myself crazy trying to figure out how to get the cursor with the axis like you get in Blender 2.49. Anyone know how to do that? The technique I use to get the pivot right requires it.

It is beginning to look something like an airplane.

abaser
02-24-2012, 10:41 PM
You mean the widget? Look at the lower header near the center. Right next to where it says "global" you will see a box with the red, blue green widget pictured. click that and make a selection.

BTW, Id be interested in hearing how that helps with doing pivots. Are you using it instead of "draw axis"?

Madratter
02-24-2012, 10:59 PM
You mean the widget? Look at the lower header near the center. Right next to where it says "global" you will see a box with the red, blue green widget pictured. click that and make a selection.

BTW, Id be interested in hearing how that helps with doing pivots. Are you using it instead of "draw axis"?

That was it. Thanks! I knew it had to be simple. I have clicked that before, and I didn't see any affect. I have no idea why.

And I use draw axis. Basically I follow the method in this post and the following posts:

http://www.knifeedge.com/forums/showpost.php?p=86911&postcount=3

abaser
02-24-2012, 11:06 PM
If you have nothing selected, I dont think it's there.

As for the pivots, that's pretty much the method I use. There is another way, but Ill leave well enough alone as the other way is tricky and unpredictable.;)

Madratter
02-26-2012, 05:29 PM
Here is a version that at least is flyable in RF6 and has physics that aren't completely crazy. It is already a fun fly. Of course, there is a huge amount of work still left. I haven't added in the engine, servos, control rods, mapping, etc. etc. etc. It's progress.

Madratter
03-04-2012, 10:58 PM
Unable to work on it the last couple of days but got some time tonight. I added the force generators.

Madratter
03-05-2012, 11:21 PM
At this point the Side Force Generators are in place and the 45 degree cuts for the surfaces have been made. The motor from Flexible has also been added.

Attached are screenshots of the physics, with the associated wings needed for the side force generators, as well as all the counterbalances for the various control surfaces.

Also attached is a flyable version although it isn't pretty because of the texture file this is currently mapped over.

dhk79
03-06-2012, 07:53 AM
One physics comment based on personal experience. I've found that using a balsa flat slab rather than a 2% flat plate works better at simulating a foamy. It is thicker and has a higher drag thereby falling out of the sky with cut power faster than the plate. I usually mix and match the two, based on the thickness of the foam.

Doug

Maj. Numbskully
03-06-2012, 09:24 AM
Are you planning on doing a stock blue or gold CS ?

Madratter
03-06-2012, 11:43 AM
One physics comment based on personal experience. I've found that using a balsa flat slab rather than a 2% flat plate works better at simulating a foamy. It is thicker and has a higher drag thereby falling out of the sky with cut power faster than the plate. I usually mix and match the two, based on the thickness of the foam.

Doug

Thanks Doug. That makes sense.

Madratter
03-06-2012, 11:44 AM
Are you planning on doing a stock blue or gold CS ?

I'm planning on doing both. :D The plane I actually own is the gold scheme.

Madratter
03-08-2012, 11:29 PM
Lots of progress has been made since the last time. Elevator and rudder servos, servo arms, control rods, and control horns installed and working. Holes cut for the servo arms and the elevator in the back. Improvements were also made to the physics model (primarily changing the airfoil and the COG).

Attached is an EA for those that want to try it in its current state.

Thanks to Flexible for the motor, and Andy for the servos, control rods, control horns, and servo arms.

booboo71
03-10-2012, 12:25 PM
Best Foamy I've flown on RF! Cant wait for the real cs! Thanks!!!

Madratter
03-11-2012, 10:21 PM
Latest version. I added the landing gear to the model and added the necessary physics support.

Madratter
03-17-2012, 09:16 PM
I added the trusses, battery, receiver, ESC, and a whole bunch of wires. I think I'm about at the point to start mapping.

Attached is the latest EA.

Madratter
03-18-2012, 08:13 PM
I have now started doing the gold color scheme. It took me a while to figure out some of the nuances of mapping under Blender 2.62. Some of this is harder than it ought to be.

Madratter
03-21-2012, 03:39 PM
I have a question about how the physics engine deals with the mass of objects.

When making calculations involving the mass of objects, where does it consider that mass to be located?

Specifically, does anyone know if it considers the mass to be located at where ever the object origin is located?

So taking the Crack Yak I am working on as an example, would it matter if the object origin of the landing gear is located at the top where it joins the fuselage or at the bottom between the wheels?

If it isn't using object origin, what is it using?

Thanks!

Boof69
03-21-2012, 04:42 PM
I'm not totally sure where the mass is calculated or what you mean by the objects origin. Do you mean pivot point? I have seen retractable landing gear affect the model's CG so I would assume that the mass is calculated by the objects volume. The wheel swinging through an arc at the end of the gear seems to prove that assumption but I don't know for sure. Am I following you right or am I way off base?

abaser
03-21-2012, 04:49 PM
Object origin is a blender term I believe. As boof said, it's more for pivots than anything as I understand. The only thing i'm aware of that affects things directly is the axis junction where the x y and z axis cross is the point of cg.

Madratter
03-21-2012, 05:09 PM
Object origin probably is a Blender term. Transforms such as moving an object are calculated from that origin point regardless of whether it is actually even in the object or not.

In terms of Boofs example, Realflight could still be using the equivalent of that zero point for the object data for doing mass calculations. It is a simple matter mathematically to figure out the new location in space of that object center point when the object pivots.

Realflight must use something as the COG for any particular part of the model that is assigned mass. The question is what.

Boof69
03-21-2012, 05:24 PM
If you want the gear to react realistically to rolling on uneven surfaces you will want the (origin) or pivot point to be located at the point where it joins the fuse as this is where it will rotate from on its Y axis. I don't believe that every part has a calculated CG.

abaser
03-21-2012, 05:24 PM
Object origin probably is a Blender term. Transforms such as moving an object are calculated from that origin point regardless of whether it is actually even in the object or not.

In terms of Boofs example, Realflight could still be using the equivalent of that zero point for the object data for doing mass calculations. It is a simple matter mathematically to figure out the new location in space of that object center point when the object pivots.

Realflight must use something as the COG for any particular part of the model that is assigned mass. The question is what.

For the most part, yes,but transformation commands can be changed to other objects such as the 3d cursor or active objects. I can't see the origin being thebase for RFs calculations since it would not be in the center for most moving parts.

I can understand boof's example of retracts affecting things. As the gear moves, it is also moving other parts. This is an interesting question though. Could RF somehow read the outer limits of objects and calculate from there, or does it really matter?

Boof69
03-21-2012, 05:28 PM
If you look at my Corsair in the editor you will see the CG move a little in the Y and allot in the Z as you cycle the landing gear. I beilive the mass is calculated by the objects volume.

Madratter
03-21-2012, 05:36 PM
There are lots of ways they could be doing this. They could use the origin point of the object. They could be using the average location of the vertices that make up the object. They could be using a weighted average (by size) of the triangle midpoints for the objects faces. With some methods, you can easily influence the calculation (object origin), others you could not (average vertices location, or the weighted average of triangle midpoint of faces).

My interest in this is that the landing gear in this model seem to be affecting the physics more than they should (based on my flying the actual model).

Boof69
03-21-2012, 05:49 PM
I believe it's the objects bounding box volume even. Notice how the fuse shape is detected in this way in the editor. Other objects added to the fuselage component will have it's bounding box detected as well. I would say that you may need to reduce the weight of your gear further to help emulate the real thing.

Madratter
03-21-2012, 05:55 PM
I believe it's the objects bounding box volume even. Notice how the fuse shape is detected in this way in the editor. Other objects added to the fuselage component will have it's bounding box detected as well. I would say that you may need to reduce the weight of your gear further to help emulate the real thing.

It will probably come down to that. I just hate not using the actual weights when I have them. :( Ah well, it is a simulation and it isn't perfect. It is still pretty good.

Boof69
03-21-2012, 06:13 PM
Concessions were less in G5.5 IMO. But however you arrive at a good simulation of the real thing is good in my book. :)

flexible
03-21-2012, 10:11 PM
If you are going to worry about the exact weight of every part, then what are you going to do about the weight of such things as servos, servo arms, servo wires. esc, linkages, and so on and so on. (The minim weight you can give something is .39 something. A servo arm does not weigh that much. THIS ONLY APPLIES TO PODS) To give anything a weight, it must have a wire frame, and component name. If you give every part a wire frame, and name and do the best you can with the weights, you're foamie will weigh twice what it should weigh. And the CG will be no where close to where it should be.
You'll NEVER get it right using a calculator, and a tallie sheet. The sim. won't let you do it that way, and come out with a good result.

dhk79
03-22-2012, 05:42 AM
I do not agree. Use the exact weights and get it as correct as possible, that way you'll get the closest performance to real life. For parts that have very low weight, give them zero and add the actual weight to its parent. These smaller parts often do not need to be named either (unless you want to make them move).

flexible
03-22-2012, 10:57 AM
I agree with Doug, as I did not do a very good job of saying what I meant. I don't give weights to small parts.
I try to get the weights forward and aft of the CG as nearly correct as I can, while keeping the total weight right.
After getting to that point, I will move weight around in order to get the CG where it needs to be, without having to manually move it, that is a last resort.

Madratter
03-23-2012, 03:38 PM
Someone mentioned having a technique that combines a foam texture with a regular color scheme to come up with a realistic looking color scheme for EPP foam planes. I have been fooling around with this and have to admit, I'm not particularly liking what I have come up with so far.

Any hints (or better yet, instructions).

Thanks!

Boof69
03-23-2012, 04:43 PM
Hint: Blending modes

What image editor are you using.

flexible
03-23-2012, 04:58 PM
Here is a EPP tga. file. Gerald has a method he uses.

Madratter
03-23-2012, 04:59 PM
Photoshop. I have been playing with the various blending modes and haven't come up with the magic answer yet. Some like multiply at least are usable, but are just not quite there for me yet.

Madratter
03-23-2012, 05:00 PM
Here is a EPP tga. file. Gerald has a method he uses.

Thanks Flexible. :D I assume that is the same one which is in the parts bin. I was in fact planning to use that as it is better than the texture I used on my Edge 540.

flexible
03-23-2012, 05:18 PM
The method I use is, I put the EPP tga on a layer over the base tga. I then make it transparent. I then cut out each part, one at a time and paste them to a new layer. That gives me a plane that is all unpainted EPP. I then open defferant picks of the paint scheme, and loop copy and paste just each section of the CS, on a new layer. merge you're layers.

Boof69
03-23-2012, 05:31 PM
Try some of the darker blending modes and adjust the fill to suite. Usually works like a charm for me.

Madratter
03-23-2012, 06:03 PM
Ok, thanks guys. I'll do some further fiddling with this.

Madratter
03-24-2012, 09:25 PM
Screenshot of my latest.

Boof69
03-24-2012, 09:28 PM
How much of those graphics are hand made? It looks very well done. Awesome!

Madratter
03-25-2012, 03:02 PM
How much of those graphics are hand made? It looks very well done. Awesome!

I'm not that good. I've been doing this with the permission and cooperation of Twisted Hobbys.

opjose
03-25-2012, 08:43 PM
I agree. It looks good.

Madratter
03-25-2012, 10:04 PM
I agree. It looks good.

Thanks!

Madratter
03-27-2012, 10:31 PM
More refinements. I have done a lot of work on the physics this time around. I'm about ready to post this to the swaps although I still have some cleanup work to do.

Comments now before I post to swaps would be useful.

Thanks!

Madratter
03-29-2012, 10:52 PM
This has now been posted to the swap pages.

http://www.knifeedge.com/forums/downloads.php?do=file&id=16517

Madratter
04-05-2012, 07:17 PM
I made some minor modifications to fix some mapping errors. I have posted the new version to the swaps:

http://www.knifeedge.com/forums/downloads.php?do=file&id=16548

I also did the blue color scheme for the plane. It is the default for v2. The gold color scheme is still available.