Bit of time in the last week to start working on my BT-80 version of the X-15. 3D printed parts are in gray, plywood parts are in yellow, body tubes are in a tan (slightly darker yellow).
X-15 (3D printed parts + BT-80 body tubes + plywood fins)
- Thread starter BigMacDaddy
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Thanks! I am planning a 24mm mount so hoping that an E12-4 will work. I will print everything else before the motor mount so I can adjust if I need to...
Definitely following as well. Being able to 3D print the hard parts of the X-15 is a huge boon!
So it does look like this model will need a fair amount of nose weight -- 3oz -- which puts is past where an E12-4 will launch it. ;(
I think that I may be able to get the weight down but also want to see if I can move CP back as well. What do you guys think of me including skids in the model? I think these will add some drag and will basically work like another pair of fins...
The real model has skids when it is landing / taking off (although it also has a wheel in front at the same time).
I think that I may be able to get the weight down but also want to see if I can move CP back as well. What do you guys think of me including skids in the model? I think these will add some drag and will basically work like another pair of fins...
The real model has skids when it is landing / taking off (although it also has a wheel in front at the same time).
What if you over/under clustered it to match that picture?
Sure -- could easily get a 2x 24mm engines (2x D12-3/5 will lift a ton) or 3x 18mm cluster in there.
One configuration of the rocket plane was with a pair of engines like in the picture above so the 2x over-under D's could be a good configuration...
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I don’t think the skids would look right without the nose gear. I’d leave them off and find a different solution like the clusters recommended above…
I am using Tinkercad -- it has tons of limitations but I am old and it was the 1st software I learned since doing AutoCAD in college... My 9 yo uses Blender which is much more powerful...
Had a bit of time this morning to make the 2-engine cluster mount... Plenty of power with a pair of D or E engines to list as much nose weight as I can add...
I'm always amazed at what can be done with TinkerCAD. I use Fusion 360, although, I've thought about switching to FreeCAD. Not a fan of the cloud when it comes to CAD stuff. Even though FreeCAD is much less polished. Again Very nice work! Excited to see this come together off the monitor and into the real world!
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You should try some of the light weight PLA out there. I have a roll of Color Fab but others make it as well. It's more expensive but worth just a roll to try. I've found it's about 30-40% lighter than the PLA I normally use (Hatchbox). I paid ~$30 for a 1 lb roll some time ago, now it's almost $40. I'd stay away from eSun...they are just price gouging for the same thing...
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I actually print with ABS so that I can do motor mounts and everything from the same filament - ABS is 20% lighter than PLA so that is a start...
Saluki
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For us that use PLA don't we have to take in the heat factor?
The way your cluster mount is set up wouldn't the heat of the motors melt the housing around the motors.
Looks to me the motors would have to stick out the back of the unit holding the motors.
The way your cluster mount is set up wouldn't the heat of the motors melt the housing around the motors.
Looks to me the motors would have to stick out the back of the unit holding the motors.
That is why I use ABS since it is more heat resistant. It is possible that the boat tail might get scorched (not totally sure how much the blast spreads out in 1.5 - 2cm.
In the past I have done lots of motor mounts from ABS and they have held up really well. Here is a mini-engine mount where the engine was directly against the ABS plastic in the boat tail. Just surface scorching but no real damage to ABS (should have primed the tail before flying to protect the plywood).
Here is an example of what the ejection charge does going through an ABS adapter (24mm D to E size). Holds up very well.
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Shouldn't the motors extend flush with the boat tail? That should keep any scorching to a minimum.
Good point -- thank you for pointing that out. I think I had recessed it some to help with CP via GDS. I moved them back since I added the 2nd engine so do not have to worry so much about nose weight!
How are those double retainers going to work?
Bit of creativity and some smoke-and-mirrors
Similar design to the cluster mounts I have done elsewhere...
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Any reason you don't want to just to to a single 24mm composite? Cost can't be more than a pair of D motors and you'll need less nose weight?
Frank
Frank
Very cool.
No good reason, just have not used them (and don't have any)...
I printed them very thin - .8mm walls. Hope I can get parts lined up and installed on body cleanly...
7 hours or something... 168mm tall for the tallest ones.
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