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Aug 07, 2018, 08:17 PM
Fly 3D Mon!
3DMON's Avatar
Nice work man! Glad to see it flies.
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Aug 07, 2018, 08:41 PM
Retired CAD guy
birdofplay's Avatar
Ahh It's great to see the Cascades , albeit , in the distance.
Winatchee off in the NW no doubt.

Looks like a winner.

I found the same with the Gasb wing which only needed a "good" toss to get going.

With all your abuse it seems to prove to be quite durable.

WAY more than enough speed wheeeew !

Guys will be printing the crap out of this design.

Congratulations.

Bob
Aug 07, 2018, 09:13 PM
Registered User
localfiend's Avatar
Thread OP
Quote:
Originally Posted by derfred
Flies very well. Congratulations!

Where is the c.g. located after all?
CG ended up 2" forward of the leading edge from the exact center of the plane. See the green line on the attached picture. I think it may be possible to move it back some, but it flew very well right where it was at. I think with the CG moved back a bit further, you could use a bit less up elevator when flying inverted.

I used a 2650 4 cell, and had it pushed all the way up in the nose just cause I figured it was safest to be nose heavy. AUW was 1065 grams or 37.5 ozs. Also, in that nearly 6 minute flight, I only used 1135mAh. So a smaller pack, and a bit of nose weight (or FPV gear) would not be a problem at all and you're not losing much. I don't generally fly the fast stuff for much longer than 5 minutes anyway.

Quote:
Originally Posted by birdofplay
Ahh It's great to see the Cascades , albeit , in the distance.
Winatchee off in the NW no doubt.

Looks like a winner.

I found the same with the Gasb wing which only needed a "good" toss to get going.

With all your abuse it seems to prove to be quite durable.

WAY more than enough speed wheeeew !

Guys will be printing the crap out of this design.

Congratulations.

Bob
Yup, Wenatchee is to the NW. Bout 1.5 hours away. It held up pretty well for as much as I beat on it. The next one I print out will be flown at a flying field with nice grass to land on though lol.

The speed with the 2306 2400kv, 6045 prop, and 4 cell was quite nice. Nothing crazy, and easy to handle. I think the plane would probably slow down a good bit if you used something with a bigger slower prop. Was just too much fun to bother with flying anything below half throttle. I am curious what it was getting to, probably not any faster than 80mph, but I'm not a good judge of speed.
Aug 07, 2018, 09:33 PM
Registered User
localfiend's Avatar
Thread OP
I may be wrong about how fast it was going at full throttle. Prop calc says the pitch speed is 114mph and the estimated top speed in level flight is 97mph. So who knows. It's a slippery air frame, not a lot of points of drag. I'll have to see if I can find a radar gun.
Aug 07, 2018, 11:14 PM
My planes plow into the field
farmertom's Avatar
Quote:
Originally Posted by localfiend
And here we go.
Looks like you have a winner on your hands! Congratulation. So on the first launch attempt why did the motor not start?
Aug 07, 2018, 11:33 PM
Registered User
localfiend's Avatar
Thread OP
Quote:
Originally Posted by farmertom
Looks like you have a winner on your hands! Congratulation. So on the first launch attempt why did the motor not start?
I didn't even try. Was attempting to throw it as hard as I could, and ended up crushing the fuse with my thumb, which didn't exactly make it travel straight lol.
Aug 07, 2018, 11:38 PM
Registered User
Awesome work!
But how am I ever supposed to finish all of my other planes when guys like you go an build something that is to cool not to print?

Have you considered using carbon rods at least on the fuselage rather than relying on glue joints alone? They would give some serious strength and support which would be great for those bad tosses that everybody will eventually have. Look at the Kraga Maripi for an example of how the carbon rods are used. This might even be a good way to shave some more weight off of this already awesome design.
Aug 08, 2018, 01:44 AM
Registered User
localfiend's Avatar
Thread OP
Quote:
Originally Posted by Mochanic
Awesome work!
But how am I ever supposed to finish all of my other planes when guys like you go an build something that is to cool not to print?

Have you considered using carbon rods at least on the fuselage rather than relying on glue joints alone? They would give some serious strength and support which would be great for those bad tosses that everybody will eventually have. Look at the Kraga Maripi for an example of how the carbon rods are used. This might even be a good way to shave some more weight off of this already awesome design.
At least it's a relatively quick print, and a really fast build. Not a lot to set up on it.

Thought about carbon for the fuselage, but I don't think it's going to add any additional strength in a crash, as what usually breaks in a survivable crash are the wingtips and nose. You end up needing to reprint those tips, and they can be harder to replace if there's a spar running through them. Also, the other thing that will break more often than not, is the outer skin. The Maripi is a bit more durable in that area not being coated in a brittle shell. I'd kinda rather have the extremities crumble and then be able to be replace rather than transferring the crashing forces deeper into the heart of the plane.

I don't know if you saw it or not, but the center wing section has a slot for a carbon arrow spar. It may not be needed either, but better safe than sorry at speeds approaching or surpassing 100mph. I'm also already riding the limit of required printed spars, any less, and you won't be able to keep proper skin tension and the plane will get lots of sags in the outer surfaces. Not really easy to go any lighter currently without using something like a smaller print nozzle. The majority of the weight comes from the outer surface.

What I'd really like to do, whenever I get more time, is make the most likely to break sections easily replaceable. Either snapping or bolting on.

Hopefully bad launches will not be a problem anymore now I know it only takes a gentle toss. I added some grip area to the sides of the fuse, and some additional spars to strengthen that area.
Aug 08, 2018, 02:59 AM
Registered User
Thoemse's Avatar
Looks like it flies really well and that landing! Considering it did not shatter into a thousand pieces after that - lets call it sub-optimal landing, is nothing but spectacular. You designed a real winner there. I must print one. This looks like the perfect plane to keep in the trunk.
Aug 08, 2018, 11:13 AM
Registered User
Quote:
Originally Posted by localfiend
What I'd really like to do, whenever I get more time, is make the most likely to break sections easily replaceable. Either snapping or bolting on.
I was thinking about this, and came up with an idea that I believe would work great. You could glue threaded steel rods inside of a carbon rod about an inch deep, that way you just sandwich everything into place and tighten up nuts on the end to pull everything together and in a crash you simply slide it apart to replace any damaged sections. (You could also glue threaded aluminum stand-offs inside the carbon rod and use bolts rather than nuts)

I just don't care to much for the printed skin, it's just to brittle, but at least if the whole plane came apart easily it wouldn't be a big deal to fix. You could even print spare parts and replace them at the field if necessary.
Aug 08, 2018, 12:05 PM
Registered User
localfiend's Avatar
Thread OP
Quote:
Originally Posted by Mochanic
I was thinking about this, and came up with an idea that I believe would work great. You could glue threaded steel rods inside of a carbon rod about an inch deep, that way you just sandwich everything into place and tighten up nuts on the end to pull everything together and in a crash you simply slide it apart to replace any damaged sections. (You could also glue threaded aluminum stand-offs inside the carbon rod and use bolts rather than nuts)

I just don't care to much for the printed skin, it's just to brittle, but at least if the whole plane came apart easily it wouldn't be a big deal to fix. You could even print spare parts and replace them at the field if necessary.
Yeah, was thinking of something similar. May give it a shot. Think I'll order some misc carbon rod sizes just so I have them on hand for this kind of thing.

I started uploading all the parts to thingiverse last night, and it looks like it was mostly successful. Still have to add in some factory files and print instructions, but posted files are close. If I can get some time at lunch maybe I'll be able to wrap things up on that front.
Aug 08, 2018, 01:49 PM
Registered User
localfiend's Avatar
Thread OP
I've posted the files over on Thingiverse for the 36" version. They're free, but if you want to donate something via paypal (link below) or tip me on thingiverse I won't say no. If you can't give anything, don't worry about it. Have fun!

https://www.thingiverse.com/thing:3040294




Last edited by localfiend; Aug 08, 2018 at 03:36 PM.
Aug 08, 2018, 05:55 PM
Registered User
localfiend's Avatar
Thread OP
Also, I think I have the mini 27" version figured out but haven't had a chance to test print it yet. I'd like to make sure it all goes together before posting to thingiverse. If anyone wants to test or try out the mini, PM me and I can send over the files.

The mini has had the firewall and servo slots reconfigured as well as a few small other tweaks. Should take your typical miniquad motor. Probably anything between the weight ranges of 15-25 grams would do well. Servo slot sizes are meant to fit the HXT500 which as far as I can tell seems to be the standard 5 gram size. Could probably change that if there's consensus on a more universal option. Don't know yet what size battery it will take, that'l be part of the testing process. But I think a 1300 should still fit into the hatch without too much trouble.
Aug 08, 2018, 06:21 PM
Retired CAD guy
birdofplay's Avatar
Well so far I have two false starts due to PETG adhesion issues.
It was looking so good until it fell off the build bed 8>{
I was using Magigoo the first attempt
next I tried Filibond -both no go's at 58 degrees.

I have resliced with the following changes from your provided factory file.

Removed Helper discs and replaced with a Raft.
jacked up the bed temp to 65

I may try Magigoo 1st at the new temp.

C U L8r

Bob
Last edited by birdofplay; Aug 08, 2018 at 06:29 PM.
Aug 08, 2018, 06:38 PM
Registered User
localfiend's Avatar
Thread OP
Quote:
Originally Posted by birdofplay
Well so far I have two false starts due to PETG adhesion issues.
It was looking so good until it fell off the build bed 8>{
I was using Magigoo the first attempt
next I tried Filibond -both no go's at 58 degrees.

I have resliced with the following changes from your provided factory file.

Removed Helper discs and replaced with a Raft.
jacked up the bed temp to 65

I may try Magigoo 1st at the new temp.

C U L8r

Bob
PETG bed really needs to be around 90C. I better go check the thingiverse instructions, the provided settings were all for PLA. I'm still working up the magic sauce for PETG. I've had really good luck with adhesion with just a little gluestick and 90C bed temps for non-thin wall parts with PETG.


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