"Finless" Rocket Design - Ram Air Intake Stabilization?

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Also just as a update to the original thread, I did get some working models of this finless design to fly well enough to be considered stable; however I'm still not happy with it...way too heavy and inefficient. I'll continue working on things this winter.
 
For a model rocket, I would think that it would be very difficult to do since you need significant mass for a noticeable gyro effect and mass on the rear end is bad mojo. Additionally, there are so many other factors affecting the flight of a model rocket which likely have much more effect that it would be hard (and $) to make a precise enough rocket that goes fast enough for those gyros to have any significant effect.

...so says my mindsim. :wink:

However, I think having "spinning wind paddles" in place of fins on a rocket would be mad-fun and likely would be a cool sounding flight, but landing damage may be an issue there (rear chute ejection?). Dang...you guys keep popping ideas into my head faster than I can build them! :tongue:

Since the fin flaps are what's turning (and then, in turn, the rocket) the gyroscopes only have to have a significant amount of mass compared to the flaps, and if you angle the hinge enough (the angled hinge is what lets the gyroscope turn the flaps to oppose the turning- I think.), a smaller gyroscope should have more leverage, If you look up a picture of a sidewinder, the rollerons are actually quite small considering the size of the rear fins. The issue would problably be calibrating the rocket so it doesn't oscillate back and forth as the gyroscope overcompensates.
However, for a small flight rocket, I agree that the rollerons will problably have little effect on the rocket, especially for the weight. And difficult to make!

It would be a cool thing to test in a wind tunnel is all I'm saying... well, and everything else I said.
 
Very difficult to make efficiently. The Sidewinder rollerons are small, but they spin really fast.
 
Very difficult to make efficiently. The Sidewinder rollerons are small, but they spin really fast.

Yep. I was wondering, though, could rollerons be spun up (say, by an air compressor) before launch? That way it won't have to be spun up to speed during the boost.

Just a thought.

-Tony
 
Yep. I was wondering, though, could rollerons be spun up (say, by an air compressor) before launch? That way it won't have to be spun up to speed during the boost.

Just a thought.

-Tony

It may be better to try small gyros taken out of the old mechanical RC gyros (used in the past on RC heli servos and likely found cheap on ebay nowadays). You can try to spin them up with a compressor, but I'd guess you'd have a hard time getting them all spun up fast enough (and evenly) to be able to launch them before they slow down. At organized club launches, it can be 10+ minutes before your rocket launches!

BTW - I think this would make an excellent separate thread - include pics and sketches too!
 
Yep. I was wondering, though, could rollerons be spun up (say, by an air compressor) before launch? That way it won't have to be spun up to speed during the boost.

Just a thought.

-Tony

They run fast both because of air speed and because they have very little friction. On one of the forums there was someone who flipped one by hand and was amazed at how long it went. I'm sure there are people here who could build some, but I couldn't.

The idea of pre-spinning them might be a good idea.
 
It may be better to try small gyros taken out of the old mechanical RC gyros (used in the past on RC heli servos and likely found cheap on ebay nowadays). You can try to spin them up with a compressor, but I'd guess you'd have a hard time getting them all spun up fast enough (and evenly) to be able to launch them before they slow down. At organized club launches, it can be 10+ minutes before your rocket launches!

BTW - I think this would make an excellent separate thread - include pics and sketches too!

Sorry to continue the hijack...but...

At our launches I often have some special requirement that makes me go first, last (most common), or a planned hold to let me run out to the pads.
 
Okay, here's the promised update!

I actually got farther than I may have lead you guys to believe. I had many good flights, but also many more bad ones. In the end I came up with some designs which seemed stable enough to have some testers try them out (unfortunately I only got feedback from one tester when I had sent out kits to 5). I may one day sell it as a kit, but for now I'd like to develop it more and possibly make the mini SSC (Spiral Spin Can) design a kit first...much more stable and less "heads-up". :wink:

Here's some pics of the designs I came up with...all but one I've gotten stable/stable enough flights from:

Here's one of the best and most fun ones...I called it "RAIStone" and sent this one out as kits with printed body wraps:
2016-05-08%2011.10.42.jpg


This specific one is actually a variant with double outlets...others had a single wider one which I later stuck with for simpler construction as a kit. I also experimented with width, height, single and dual outlets as well as angled and side-vented vents (to induce spin). I also tested nose weights, bt length, intakes as well as different attached "nozzles". Soooo much testing!

Here's a video of one of these launched at my local park and then at a club (note I've launched on 1/2A3 through A10s):

[video=youtube;025oPt2skJ8]https://www.youtube.com/watch?v=025oPt2skJ8&feature=youtu.be[/video]

[video=youtube;6bjw6lqies8]https://www.youtube.com/watch?v=6bjw6lqies8&feature=youtu.be[/video]
 
Here's a fun variant I particularly liked...a Ramjet versions! One was straight body and the other had an open center. I liked the way these flew too and would like to one day make it a kit as well:

2016-05-08%2011.12.34.jpg


2016-05-08%2011.14.21.jpg


Sample Flight (I think the streamer broke or failed to come out on this one):

[video=youtube;hFzfleBwT5Y]https://www.youtube.com/watch?v=hFzfleBwT5Y&feature=youtu.be[/video]
 
Okay, here's the promised update!

I actually got farther than I may have lead you guys to believe. I had many good flights, but also many more bad ones. In the end I came up with some designs which seemed stable enough to have some testers try them out (unfortunately I only got feedback from one tester when I had sent out kits to 5). I may one day sell it as a kit, but for now I'd like to develop it more and possibly make the mini SSC (Spiral Spin Can) design a kit first...much more stable and less "heads-up". :wink:

Here's some pics of the designs I came up with...all but one I've gotten stable/stable enough flights from:

Here's one of the best and most fun ones...I called it "RAIStone" and sent this one out as kits with printed body wraps:
2016-05-08%2011.10.42.jpg


This specific one is actually a variant with double outlets...others had a single wider one which I later stuck with for simpler construction as a kit. I also experimented with width, height, single and dual outlets as well as angled and side-vented vents (to induce spin). I also tested nose weights, bt length, intakes as well as different attached "nozzles". Soooo much testing!

Here's a video of one of these launched at my local park and then at a club (note I've launched on 1/2A3 through A10s):

[video=youtube;025oPt2skJ8]https://www.youtube.com/watch?v=025oPt2skJ8&feature=youtu.be[/video]

[video=youtube;6bjw6lqies8]https://www.youtube.com/watch?v=6bjw6lqies8&feature=youtu.be[/video]

Good job!

It seemed to go unstable after the boost, I would think because the air was no longer being forced into the tube.

For the engine retainer, I've used the "less plastic" type water bottle caps. They're less protruding, but I haven't gotten to fly them yet, so...

Have you tested isosceles triangles (vertex at the top), or different shaped fin slots? It might create a different fin profile.

The square slot *should* produce a swept back parallelogram and the triangle *should* produce an alpha style fin.

Anyways...

I like it!
 
Once I had designs which I felt flew well enough, I started upscaling them (note that I found the minis to be a LOT of fun and great for a decent sized park). I made 18mm mmt versions and launched them on B6 and C6 at my club ("Heads Up!" flights of course).

2016-05-14%2011.02.22.jpg


Here's a video of the RAIStone...I had trouble lighting the Ramjet, but after all but one person had left, I got it launched and the observer thought it was a beautiful flight (no video though). Note that it was windy and that the C6 flight (second video) weathercocked over the river on our right and then the wind blew it back to the field even though it was on a streamer.

[video=youtube;oB_fga7l6Nw]https://www.youtube.com/watch?v=oB_fga7l6Nw&feature=youtu.be[/video]

[video=youtube;UMqm7UNp1tc]https://www.youtube.com/watch?v=UMqm7UNp1tc&feature=youtu.be[/video]

At least I got the "windy conditions" testing out of the way! :wink:
 
Okay, here's the promised update!

I actually got farther than I may have lead you guys to believe. I had many good flights, but also many more bad ones. In the end I came up with some designs which seemed stable enough to have some testers try them out (unfortunately I only got feedback from one tester when I had sent out kits to 5). I may one day sell it as a kit, but for now I'd like to develop it more and possibly make the mini SSC (Spiral Spin Can) design a kit first...much more stable and less "heads-up". :wink:

Here's some pics of the designs I came up with...all but one I've gotten stable/stable enough flights from:

Here's one of the best and most fun ones...I called it "RAIStone" and sent this one out as kits with printed body wraps:
2016-05-08%2011.10.42.jpg


This specific one is actually a variant with double outlets...others had a single wider one which I later stuck with for simpler construction as a kit. I also experimented with width, height, single and dual outlets as well as angled and side-vented vents (to induce spin). I also tested nose weights, bt length, intakes as well as different attached "nozzles". Soooo much testing!

Here's a video of one of these launched at my local park and then at a club (note I've launched on 1/2A3 through A10s):

[video=youtube;025oPt2skJ8]https://www.youtube.com/watch?v=025oPt2skJ8&feature=youtu.be[/video]

[video=youtube;6bjw6lqies8]https://www.youtube.com/watch?v=6bjw6lqies8&feature=youtu.be[/video]

This was a fun build and flew well! I really like the strake design!
 
Good job!

It seemed to go unstable after the boost, I would think because the air was no longer being forced into the tube.

For the engine retainer, I've used the "less plastic" type water bottle caps. They're less protruding, but I haven't gotten to fly them yet, so...

Have you tested isosceles triangles (vertex at the top), or different shaped fin slots? It might create a different fin profile.

The square slot *should* produce a swept back parallelogram and the triangle *should* produce an alpha style fin.

Anyways...

I like it!

Thanks! I've actually tested triangular a bit (tested a LOT of things), but there wasn't a significant enough difference in this scale to notice a difference. I did stick it on one version with triangular forward canard vents...stay tuned!
 
Here's one failed version...I tried to copy the Estes crayon (real one on the left and finless is on the right). I thought it'd be cool to bring up a crayon rocket without fins and fly it. :) I think there wasn't enough nose weight/not enough boost/not enough venting/insufficient speed. It seems close though, but back to the drawing board...

2016-05-14%2010.44.49.jpg
 
Here's one failed version...I tried to copy the Estes crayon (real one on the left and finless is on the right). I thought it'd be cool to bring up a crayon rocket without fins and fly it. :) I think there wasn't enough nose weight/not enough boost/not enough venting/insufficient speed. It seems close though, but back to the drawing board...

2016-05-14%2010.44.49.jpg

When on sale, these should be a cost effective testbed!
 
Good job!

It seemed to go unstable after the boost, I would think because the air was no longer being forced into the tube.

For the engine retainer, I've used the "less plastic" type water bottle caps. They're less protruding, but I haven't gotten to fly them yet, so...

I forgot to address those other two items...I do have videos of this design coasting. However part of the problem is the heavy weight, small mini motors and high drag tends to have the rocket slow down very quickly. I actually found a good way to make plastic screw on retainers for the mini rockets (trade secret for now), but the ones I made for the 18mm started failing since they weren't up to the ejection charges. Do you have postings on the bottle cap retainers you've used and how much have you tested them?
 
Side note is that one great benefit of this design is it's compactness and not having to worry about bending/beaking fins!

2016-05-20%2007.07.10.jpg


2016-05-20%2007.08.25.jpg


Here's the box closed with 7 mini rockets in it!

2016-05-20%2007.20.00.jpg

They look cute in that pocket rocket protector. :)
 
I don't have data on the heat resistance of the bottle cap one, unfortunately. Haven't been to any launches recently. I have though about putting a piece of card stock in to reinforce the cap. Might help with ejection too.

The cap only supports the paper motor tube, so the aperture might be too small on yours. (Just speculation)
If it covers more than the tube, you should be able to widen the hole until it's ID is the same as the motor tube's without structural ramifications.


The bright side for the bottle cap method is that as long as I keep drinking from water bottles, I'll always have replacement screw caps.


Is trade secret synonymous with glitter bottle?
 
I'll test it if you post the plans.

Please...

Sorry, but not for a while at least...the construction is actually quite demanding - fit is very critical and vents have to be cut very precisely. Also since this is an experimental design, I have to be very careful about testers and who I provide the instructions to...I'd hate for some bad incident to give this design a bad rap. I was very careful with my testing and only got so far by doing a lot of trials on small scale on private fields with no one around. Only through small steps could I ensure that the rockets wouldn't be wildly unstable. This is how I managed 200+ flights by summer!
 
Sorry, but not for a while at least...the construction is actually quite demanding - fit is very critical and vents have to be cut very precisely. Also since this is an experimental design, I have to be very careful about testers and who I provide the instructions to...I'd hate for some bad incident to give this design a bad rap. I was very careful with my testing and only got so far by doing a lot of trials on small scale on private fields with no one around. Only through small steps could I ensure that the rockets wouldn't be wildly unstable. This is how I managed 200+ flights by summer!
I understand.

No need to be sorry, I have another project that I'm working on... or two... or three... or...

Ten.

Even if you did share it, it would problably end up half built in my parts bin.


-Tony
 
Here's some fun I tried to have with the finless design...these were meant to be a test to see if the design can make what others would assume to be unstable rockets fly stable...almost like rocket magic! :cyclops:

What's brown and "sticky"? (note the triangular "canard" vents as well as slanted vents)

2016-03-26%2007.26.08.jpg


[video=youtube;nWy3_2GCnXs]https://www.youtube.com/watch?v=nWy3_2GCnXs&feature=youtu.be[/video]

I later wanted to go with the "magic" theme and tried a version as a magic wand which I can keep up my sleeve and pull out at the RSO table. :lol:

2016-04-10%2007.45.54.jpg


However this one seemed to be a bit too heavy for the motors I had available...

[video=youtube;3q4KBDgqaJE]https://www.youtube.com/watch?v=3q4KBDgqaJE&feature=youtu.be[/video]

Here's one that's really starting to push things...my "WhatSideDown?" (WSD) rocket...looks like a regular rocket, but you then put it on the rod apparently "upside down". This one seemed even heavier and draggier, so it will take more work, but it was fun to make (note the intakes are inside the "fins").

2016-04-10%2007.40.23.jpg


I couldn't get it stable enough to my liking, but I had one version which was marginal on the smaller motor and I think I was getting close...

Video of WSD on 1/2A3:
[video=youtube;A05KoHn1z6w]https://www.youtube.com/watch?v=A05KoHn1z6w&feature=youtu.be[/video]

Video of stretched/modified WSD:
[video=youtube;ZzFG93NlCSM]https://www.youtube.com/watch?v=ZzFG93NlCSM&feature=youtu.be[/video]

I've got a few other designs not shown and other things even more complex I'm working on with this design, so hopefully I'll have some success on things next year...stay tuned and thanks for watching! :)
 
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