Fly-away rail guides: 54mm 3D-printed available now

[wfcook]

I want one in ABS.

Yeah, me too. I am working towards that capability, as well as the ability to make them larger.

 

[djkingsley]

I will be flying a set tomorrow at the MDRA launch. If anyone wants to try them afterwords let me know.

 

[junkyard]

As for slippage between the body and the guide, you only need more friction in the sleeve than you have at the guides (plus a factor of safety that should be greater than the μs/μd ratio) and it shouldn't budge unless the guide hits a snag in the rail. In the worst case scenario you could print the guides for a slightly larger body dimension and coat the inside with a rubberized material to gain a higher μ.

Can't wait to see it in action!

That is not entirely true, you have to also consider the change in momentum. With small slow rockets it might not be an issue, but as you scale to higher initial thrust it will.

 

[rockdoc]

I really would like to see these in action. Sorry I had to cancel the launch for the 18th due to weather. I hope the conditions are better next weekend.

Larry, I'll be at the Plan B launch Sunday at Bob's and have them for testing.

 

[wfcook]

djkingsley had a successful launch of his DarkStar Mini (first flight on an F59) on a set of the new rail guides today, for which I thank him. They worked perfectly! Unfortunately his tracker wasn't working, and he doesn't have his dual deploy setup finished quite yet, so we weren't able to plug in a bigger motor today. Hopefully rockdoc will be able to get in something with a little more zip tomorrow.

My photographic skills weren't quite good enough either...missed it by that much, as the lower guide is just barely still in the rail:



More to come, and I'm getting geared up to make these available.

 

[djkingsley]

The mini dark star left the rod perfectly, the rail guides flew about 10-12 ft from the launch pad. There was a little bit of scuff on the rail guide but no erosion of the plastic. I am very happy with them.

 

[Viperfixr]

Is it possible to buy these yet? I'd really like a 38mm pair.

 

[grouch]

I'm in for a set as soon as they are available.

 

[Cyril's Scribe]

I am definitely in for two 38mm pairs and I would love to get my hands on a pair for 54mm and/or 3 inch rockets. I am finishing the build process for a 3inch rocket that could use these and I am starting to build a minimum diameter 54mm rocket...

 

[wfcook]

Adrienne Ramey caught a video of djkingsleey's launch, and you can see the guide (Thanks Adrienne!):

[video=youtube;G19Lz09WkJY]https://www.youtube.com/watch?v=G19Lz09WkJY[/video]

 

[ksaves2]

Boy, that worked like a charm. If ya come up with 'em that will fit on a LOC tube I'll be game for a few pair. Going to run a J350 and glass the 1/8" plywood fins in the 1/3rd, 2/3rds and full span fashion. Kurt

 

[Buckeye]

These are coming along nicely. Well done.

 

[wfcook]

I took some frame grabs from Adrienne's video. The frames are 0.04s apart, and I think the rocket is still on the rail for the first three here. So it looks to me like the guides cleared the rocket fairly quickly:

 

[etoyoc]

Saw 3 or 4 successful launches with them today. No real wear on them. We also discovered that they would fit a mini rail; however, they wouldn't slide as nicely. We didn't launch off a mini rail, but it may have worked.

I certainly plan on getting some of these.

 

[rockdoc]

Launched today using the "Fly away rail guides", and another successful launch using the new improved rails. Total of 3 flights. I took video and captured the frames. No wear on the guides whatso ever and on a 1010 rail they slide on and off with little resistance.

View attachment 252100 View attachment 252101 View attachment 252102 View attachment 252103

 

[Ravenex]

Would it be possible to incorporate a torsion spring in the hinged version instead of the rubber bands? Also to add friction with the rocket to prevent slipping, and to help with not scratching paint and with accommodating various tube manufacturers and wall thicknesses you could make them slightly over-sized and add a compressible foam rubber like weatherstripping to the inside.

 

[wfcook]

Would it be possible to incorporate a torsion spring in the hinged version instead of the rubber bands? Also to add friction with the rocket to prevent slipping, and to help with not scratching paint and with accommodating various tube manufacturers and wall thicknesses you could make them slightly over-sized and add a compressible foam rubber like weatherstripping to the inside.

I've thought about that, but a key element of the design is that the lever arm from the rubber band hooks is extremely small when the guides are in the closed position, but increases dramatically as the guides open. This is how they achieve such low rail friction while still opening quickly. I think with a torsion spring they'd end up with too much outward pressure on the rail slot, but I'll draw the free body diagram again and think about it.

As for slipping, it hasn't been much of a problem since they are back against the fins at launch. But I am thinking about the issue because so many people have brought it up, and I will work on it.

 

[wfcook]

Launched today using the "Fly away rail guides", and another successful launch using the new improved rails. Total of 3 flights. I took video and captured the frames. No wear on the guides whatso ever and on a 1010 rail they slide on and off with little resistance.

View attachment 252100 View attachment 252101 View attachment 252102 View attachment 252103

rockdoc, those are fantastic pictures. Thanks again for doing some testing!

 

[djkingsley]

What size motor are you flying in this photo set? Excellent capture of the release!

Launched today using the "Fly away rail guides", and another successful launch using the new improved rails. Total of 3 flights. I took video and captured the frames. No wear on the guides whatso ever and on a 1010 rail they slide on and off with little resistance.

View attachment 252100 View attachment 252101 View attachment 252102 View attachment 252103

 

[rockdoc]

What size motor are you flying in this photo set? Excellent capture of the release!

Due to wind and low cover used a F27 Redline. Stay tune, next week will be testing Vmax and C-star, no doubts that they will work as designed.

 

[Bat-mite]

I was there and saw the Saturday launch. I thought it worked really well and looked cool to boot.

 

[rms]

Due to wind and low cover used a F27 Redline. Stay tune, next week will be testing Vmax and C-star, no doubts that they will work as designed.

I didn't know that there is a c-star load in anything less than 54mm?
Greg

 

[rockdoc]

I didn't know that there is a c-star load in anything less than 54mm?
Greg

Next launch will be on a I566 VMax. and The C-Star will actually be a I224 Classic.

My excitement got the better of me when I was writing up the review

 

[wfcook]

Awesome, I566 will be a great test!

 

[rms]

I566 will be a great test!
When these become available; I'm sure hoping they do, I hope to fly one on a J453 in my 38mm md.

Greg

 

[wfcook]

Assuming they pass the Vmax test, the plan is for them to become available.

 

[rms]

Assuming they pass the Vmax test, the plan is for them to become available.

Great news indeed Bill.

Greg

 

[CarVac]

If only I still had Disappearing Act to try a 200-g boost with...

 

[rms]

If only I still had Disappearing Act to try a 200-g boost with...

Perhaps a rebuild for another attempt is in order? :wink:

Greg

 

[rockdoc]

Here are some more photos of a different rocket that used the "fly away rail guides" This was one of Larry Koskie's rockets.

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