Competition Streamer question

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gpoehlein

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OK - thinking outside the box a bit here and I'd like a consensus among the NAR contest fliers here.

When flying Streamer Duration, is it necessary that the rocket remain mostly intact (IE the nose separates via shock cord and deploys the streamer as normal)? For example, assuming that all the parts remain connected together via shock cords/tethers, is there any reason a streamer rocket couldn't separate into several components. I'm thinking specifically of a body tube that splits open lengthwise to release the streamer. Thus, you would have a separate fin can, two BT halves and the nose cone, all held together via short lengths of shock cord. And the streamer, of course.
 
Missed the part about the tether when I made my 1st reply.

It's an interesting idea- making the parts of the rocket create more drag and hopefully longer durations. I think you'll run into problems with the rule about the streamer acting as the only recovery device though. Once you start splitting tubes and fin units up to make more drag I think you'll be outside the scope of the event.

kj
 
Missed the part about the tether when I made my 1st reply.

It's an interesting idea- making the parts of the rocket create more drag and hopefully longer durations. I think you'll run into problems with the rule about the streamer acting as the only recovery device though. Once you start splitting tubes and fin units up to make more drag I think you'll be outside the scope of the event.

kj

That would be hard to argue as a very common technique is to attach the shock line to the CG of the lower body (with spent motor) so that it comes down parallel to the ground for the sole purpose of adding more drag and helping the streamer out.

So, using the body of the rocket for added drag has been done for over 40 years now. This is just a more extreme example of the same idea.

*my* concern would be that whatever added drag you may cause could be lost during boost due to added weight and added drag (if the parts don't fit well). It may be a case of diminishing returns...
 
OK - thinking outside the box a bit here and I'd like a consensus among the NAR contest fliers here.

When flying Streamer Duration, is it necessary that the rocket remain mostly intact (IE the nose separates via shock cord and deploys the streamer as normal)? For example, assuming that all the parts remain connected together via shock cords/tethers, is there any reason a streamer rocket couldn't separate into several components. I'm thinking specifically of a body tube that splits open lengthwise to release the streamer. Thus, you would have a separate fin can, two BT halves and the nose cone, all held together via short lengths of shock cord. And the streamer, of course.

CMR used to make a kit that did that. The "Breakapart", or something like that I believe. The BT split lengthwise from just above the fins to just below the nose. One part was attached to the nose, and the other had the fins attached to it.

As long as all the pieces stay together, you should be fine.
 
Yep I was going to say about CMR:
Split bodies have been used off and on over the years. I;ve flown break apart and slit body paper models at various times, While you might draw a protest challange, I doubt it'd be upheld as long as every single piece is held by a single shockcord, and your 'Main" recovery method it the streamer.
 
Truth to tell, the additional drag of the broken-up body was a secondary consideration. The competition is 1/8A Streamer, and I was thinking of this design to allow for faster and better deployment of the streamer. This should allow me to install a slightly larger streamer into a near minimum diameter tube without worrying about it snagging or the ejection not being strong enough to deploy properly. Plus, I'm planning to build it all from paper/light cardstock, so it shouldn't be all that much heavier than a traditional rocket, even with the additional hardware (really, the only additional items will be four single-layer cardstock bulkheads to hold the shell halves round and hold them together. The rest will be slip-fitted to fall apart at ejection.

I'll post pics as I get farther along.
 
In competition modeling don't forget the KISS principle: Keep It Simple Stupid and its 1st cousin Murphy's Law: whatever can go wrong, will go wrong. And if all else fails remember to RTFM- Read the Fraking Manual .


am I allowed to say FRAK in here? ( must be having a BSG craving huh?)

On the other hand, you could use some of that magician's flash paper to roll your body tube, such that the tube is burned to dust in the air reducing the overall weight. The incredible disappearing modle rocket! I'm joking I'm joking

hth

terry dean
nar 16158
 
On the other hand, you could use some of that magician's flash paper to roll your body tube, such that the tube is burned to dust in the air reducing the overall weight. The incredible disappearing modle rocket! I'm joking I'm joking

hth

terry dean
nar 16158

Or just soak a vellum tube in potasium nitrate... ;)
 
I've spent the winter optimizing my FAI streamer model and have put a lot of thought into something like that as well.

In your case, I would think that the additional weight of the components would offset any benefit of a faster deployment. Also think about what would happen if your delay isn't long enough and your rocket breaks apart as it still is ascending. The increased drag of the broke apart rocket could work against you.

Insofar as getting a proper deployment, that shouldn't be a big issue if you use a foam piston. Done correctly, I can't see a break apart model necessarily being faster than the usual deployment method. Also, the with a typical deployment the streamer is ejected upwards into the air while a break apart model pretty much unfurles in place.

I would think the main benefit to a break apart rocket would be if your body tube was comprised of the rolled up streamer. That would save the weight of not needing a conventional body tube as part of the design.

All of this is assuming that you are building a super lightweight rocket to begin with. The weight of your rocket will be one of the more significant factors to being successful in this event.
 
Greg:

Please don't take this the wrong way, but I wouldn't worry about the more advanced/cutting edge stuff until you've mastered the basics first. Are you able to consistently hang a C-SD out there for 4-5 minutes a flight? If so, then you probably need to push the envelope and look at every aspect of design, including break-away tubes, streamer material, folding techniques, shock cord attachment, fin design, nose cone design, etc.

I'm no rocket scientist (really, seriously), but the idea of trying to juice the drag by having the body break up strikes me as more of a wacky mad scientist concoction than an idea that's practical on the field. You're surely adding in a drag/weight penalty to some degree for having exterior seams, joints, etc. Is that less than the gain of the break-apart body tube? Are you increasing the risk of separation, resulting in DQ? Does your less rigid model wobble slightly on the way up, wasting impulse on getting back to zero angle of attack? How many angels can dance on the tip of a parabolic nose cone?

I know on my streamer duration models, I generally just make sure I anchor the shock cord externally near the fin, such that the body descends perpendicular to the ground (with motor casing in it). The fins do a pretty good job of applying a drag force, but getting a big streamer out and wiggling in a thermal is a far more challenging attribute of flight performance, and one that I have still not mastered despite at least 100 attempts. I wish you luck in your quest for optimum body tube design, as you'll surely get there ahead of me. I intend to continue wasting my R & D time figuring out how to consistently get big streamers to deploy and to catch big air.

--Chan Stevens
 
I intend to continue wasting my R & D time figuring out how to consistently get big streamers to deploy and to catch big air.
Maybe you should work on keeping them away from water towers. :surprised: Did you get that one back?
 
ROTFLMAO!:lol:

Nope, I was so caught up in the rush of getting in my flights that I completely forgot about that one. I couldn't leave the park and get it with kite festival/traffic embargo in effect, so figured I'd stop by the water tower on my way home. Just plain forgot. Now I'm spending the night in my hotel room on the road, folding replacement streamers.

That was my safe/low performance model, by the way. As you saw, it did OK, not great, though didn't catch much air at all.

For the record, that was the first time I've ever logged three consecutive qualified streamer flights, so feel free to disregard all my advice.

--Chan Stevens
 
Oh, I'm sticking with the standard designs and foam plugs for 13mm and 18mm streamer and parachute duration. This is micromax (1/8A) streamer duration and I'm concerned about stuffing a legal (>100sq cm) streamer into that tiny little body tube and getting it to deploy. I mean, these things aren't gonna go that high any way. I just thought the break-apart design would have a better chance of deployment than a standard design in that small size. And with the design I have in mind, it shouldn't be a lot heavier than a standard 3FN cardstock or paper rocket.

Besides, I'm not that competitive any way (Chan, you KNOW the guys I'm flying against!) so experimenting and flying more unconventional stuff is fun! Given this Crue, I might as well have some fun - every contest they all wonder what crazy design I'm going to drag out this time. ;) Heck - I've got a reputation to uphold! :p
 
I would think the main benefit to a break apart rocket would be if your body tube was comprised of the rolled up streamer. That would save the weight of not needing a conventional body tube as part of the design.
Forgive my naive question, but is that legal under NAR competition rules? It sounds like an interesting idea.

I just thought the break-apart design would have a better chance of deployment than a standard design in that small size.
I have also thought about this (but never done it) as a way to pack a really big streamer into a narrow body and still get it to deploy reliably. That was before I saw some of the ultra-lightweight homemade tubing that is common in competition models.
 
Bob- a few years ago I asked the same question in most of the rocket groups and no one could find a rule that prohibited it, so long as it results in a rocket that is reusable and doesn't eject any extra parts.
 
Heh - the worst that can happen is that I either build it and decide not to fly it, or I do fly it and I don't place in the contest... which usually happens anyway, so where's the downside? :p
 
Forgive my naive question, but is that legal under NAR competition rules? It sounds like an interesting idea.


I have also thought about this (but never done it) as a way to pack a really big streamer into a narrow body and still get it to deploy reliably. That was before I saw some of the ultra-lightweight homemade tubing that is common in competition models.

For regular streamer duration, I think this is generally a no-brainer as allowed since it is not specifically prohibited. For multi-round, in which a contestant is allowed three flights but is only allowed to use two models, this is debateable/not clear. One argument=the paper wrap body tube is not reuseable and therefore by replacing the body I have used up a model. Other argument=it's like recovery wadding and is considered a flight consumable.

I've been to one national meet where this was used, it was deemed legal, and that seems at least a partial precedent.

Now, back to contemplating our respective navels over this--I don't generally accept the premise that this enables the flyer to load a larger streamer than a conventional body tube. Thin paper tube is only going to shrink the relative OD, not expand the ID, or else the motor would be too sloppy a fit. If you say the OD will be the same and just use tape on the motor, I'd then ask why not just compare to a TT-20 tube instead of a BT-20 tube? Maybe we're talking 18mm ID at the base, tapering to larger ID at the top, in which case it's more like a shroud than a body tube, is therefore higher drag, trading boost altitude for lower descent speed. Larger streamer, by the way, means larger mass=lower boost.

Come to think of it, I think tis would be a fantastic idea and strongly encourage everyone at NARAM this year to take this approach. I'll be the knuckle-dragging Neanderthal flying my plain ol' BT-20 based design, and this might afford me my first opportunity to place in a streamer event:cool:.

--Chan Stevens
 
That brings up an interesting question, Chan. In a multiround event, what about vellum rockets? By definition, although the fin can and nose cone are reusable, the vellum tube is not. It almost always has to be replaced after every flight (at least mine always have - they tend to bubble and deform a lot at ejection). So does that mean that you can't use a vellum rocket because the tube can't be reflown?
 
That brings up an interesting question, Chan. In a multiround event, what about vellum rockets? By definition, although the fin can and nose cone are reusable, the vellum tube is not. It almost always has to be replaced after every flight (at least mine always have - they tend to bubble and deform a lot at ejection). So does that mean that you can't use a vellum rocket because the tube can't be reflown?

That's exactly the issue I was trying to point out. The rule is not at all clear. Since streamer is multiround this year, it is a valid concern. The only other time I have personally seen this tested at NARAM was, coincidentally, at Great Meadows, where it was allowed/considered a consumable and did not count as a rocket body. IIRC, though, the envelope did not get pushed that far, as the flyer wound up not flying all three flights anyway, but that was my first NARAM and honestly I wasn't paying that much attention to who was doing what, and I was a long way away from being a 'big timer" myself (took me a whole 'nother year to win a NARAM).
 
I don't generally accept the premise that this enables the flyer to load a larger streamer than a conventional body tube. Thin paper tube is only going to shrink the relative OD, not expand the ID, or else the motor would be too sloppy a fit. If you say the OD will be the same and just use tape on the motor, I'd then ask why not just compare to a TT-20 tube instead of a BT-20 tube? Maybe we're talking 18mm ID at the base, tapering to larger ID at the top, in which case it's more like a shroud than a body tube, is therefore higher drag, trading boost altitude for lower descent speed.
I was not considering differences in the tube's ID. I was more concerned about using a really long tube to allow the use of a really wide streamer (still subject to the 5:1 L/W limit). It seems that a wide streamer would be likely to bind in a long narrow tube if it ejected conventionally out the nose. OTOH, if the tube split lengthwise, the streamer would unfurl quite easily.

Along that same line of thought, is there any reason that the streamer has to be on the inside of the tube? Could it be wrapped around the outside and secured with a burn string or a sliding sleeve?

Larger streamer, by the way, means larger mass=lower boost.
Not necessarily. There is an optimal mass that depend on the impulse and delay time of the motor and the drag of the rocket.
 
I was not considering differences in the tube's ID. I was more concerned about using a really long tube to allow the use of a really wide streamer (still subject to the 5:1 L/W limit). It seems that a wide streamer would be likely to bind in a long narrow tube if it ejected conventionally out the nose. OTOH, if the tube split lengthwise, the streamer would unfurl quite easily.

The majority of published and practiced methods would suggest that a 10:1 length to width ratio tends to be optimal, so longer body tube==>wider streamer is probably only an advantage if streamer is also longer. I had simply assumed use of velum over wound tube was a concern about thickness/weight, as length of wound tubes is simply not a constraint.

Along that same line of thought, is there any reason that the streamer has to be on the inside of the tube? Could it be wrapped around the outside and secured with a burn string or a sliding sleeve?

It could, but I'd think that's introducing a whole bunch of drag. The Reynolds number on something like that could be nasty.


Not necessarily. There is an optimal mass that depend on the impulse and delay time of the motor and the drag of the rocket.

True. In my experience, though, a decent 6x60 streamer in the typical 18mm model is above optimal mass for a B6-6 or C6-7. Not as big an issue with streamers as chutes, but you also need to hang enough mass (rocket body) underneath to keep the streamer flapping--if the rocket body is too light, the streamer doesn't deploy optimally, floating around in the wind rather than hanging vertically and allowing the folds to work their drag effect.
 
OK - thinking outside the box a bit here and I'd like a consensus among the NAR contest fliers here.

When flying Streamer Duration, is it necessary that the rocket remain mostly intact (IE the nose separates via shock cord and deploys the streamer as normal)? For example, assuming that all the parts remain connected together via shock cords/tethers, is there any reason a streamer rocket couldn't separate into several components. I'm thinking specifically of a body tube that splits open lengthwise to release the streamer. Thus, you would have a separate fin can, two BT halves and the nose cone, all held together via short lengths of shock cord. And the streamer, of course.

Greg, have you been talking to Dave Fitch again? ;-)

Rocketbiker
 
Greg, have you been talking to Dave Fitch again? ;-)

Rocketbiker

Actually, no... but you've SEEN some of the stuff I come up with on my own! :D

I may experiment with this idea, but after looking at it, I'm not sure I can make it aerodynamic enough to work well, so I'm building a standard 3FN paper rocket for this event. If I have time, I might try building this too, but I've got a lot of other stuff to finish in only about a week, so...
 
Actually, no... but you've SEEN some of the stuff I come up with on my own! :D

I may experiment with this idea, but after looking at it, I'm not sure I can make it aerodynamic enough to work well, so I'm building a standard 3FN paper rocket for this event. If I have time, I might try building this too, but I've got a lot of other stuff to finish in only about a week, so...

Gp:
You're looking specifically at 1/8A S/D correct? have you looked at the standing records for SD in the impulse clase? Why do you think it's SOOO long?

I really don't compete anymore for many reasons but the biggest is particuarly with SD and PD. LUCK is far more important then just about all the tech put into it.
Split bodies, side opening, and sectional airframes Have been done, and done. Optimal mass, and streamer ratio Practice not theory have all shown the winning model is the one that best fits (Are You Listening)"the Field Conditions at the time".
Build what YOU think is gonna be your best weight to thrust optimal design...or simple 3fnc model. TEST, TEST, TEST. Then assemble models, streamers, and motors to match your fields various flying conditions. You'll do just fine with the addition of a little LUCK :lol:

As for 1/8A sd: I find a taper paper model is my choice of airframes....streamer size and length depend on the day and field.

OBTW chan:
It's been Shown and proven by repetition in several recent R&Ds that the old 70's 1:10 streamer ratio MIT study was ONLY really meaningful with Crape and vellum streamer materials of the time. Other ratios with Micafilm, mylars and other materials have had proven better results. I've personally had outstanding results with 4" x 80" and 7" x 100" micrafilm streamer. thermalled several away as LUCK would have it!

MM 216a4-sm_a-f Taper&Doubletaper PD's_8-30-04.jpg
 
Ok, John - I've got a question. With your taper papers, how do you protect the chute/streamer? You can't really use a foam plug because of the BT flare. Will wadding/dog barf expand enough to protect the recovery device? Mind you, I'm not too concerned about the ejection charge since I am now using tracing paper (I LOVE this stuff!) and it doesn't seem to be as sensitive to the heat as plastic or mylar. I tried one at our last regional in a B-Streamer and it performed beautifully. Only problem was I didn't color it and the timers had a hard time following it in the haze. I've made a couple more so far and I've colored them with black marker so they should be more visible. But those things really hang!

Oh, and as far as the competition is concerned - as I said in an earlier post, several people here (you, Chan and Rocketbike) KNOW who I am competing against (actually, Rocketbike's one of them, and Chan too if he comes down and flies C class :p) - I don't really stand a great chance of winning, so I might as well at least have fun, and the experimental designs are fun to me! :D
 
Most of the old studies measured the affect of the amount of drag that each material produced. That, along with the weight, were pretty much the variables back then

That was before Mylar streamers became popular. With Mylar, you can try ironing in different types of pleats where the pleats will affect the shape of the streamer once it's deployed.

A popular method used in FAI competitions is to roll the streamer around a dowel then iron it flat. Once deployed, the streamer takes on a "C" shape that can assist in catching thermals. It's commonly known as a scorpian's tail. Another popular method is to have the pleats go back and forth in an accordian fashion. That creates a decent amount of drag but with the trade off of not catching thermals as well.

I'm in the process right now of using a force gauge to measure the amount of drag produced by differing pleats. The best versus worst pleat patterns vary by just a few tenths of a gram.

Unfortunately, there's no easy way to measure the amount of lift that can be captured by different pleat patterns.
 
Most of the old studies measured the affect of the amount of drag that each material produced. That, along with the weight, were pretty much the variables back then

That was before Mylar streamers became popular. With Mylar, you can try ironing in different types of pleats where the pleats will affect the shape of the streamer once it's deployed.

A popular method used in FAI competitions is to roll the streamer around a dowel then iron it flat. Once deployed, the streamer takes on a "C" shape that can assist in catching thermals. It's commonly known as a scorpian's tail. Another popular method is to have the pleats go back and forth in an accordian fashion. That creates a decent amount of drag but with the trade off of not catching thermals as well.

I'm in the process right now of using a force gauge to measure the amount of drag produced by differing pleats. The best versus worst pleat patterns vary by just a few tenths of a gram.



Unfortunately, there's no easy way to measure the amount of lift that can be captured by different pleat patterns.


great idea Pat!. Will this become a R&D report?

terry dean
 
I've also tried tracing paper streamers--great hang time but you can't beat metallic mylar for visibility on a sunny day. I've had a rocket land in an unrecoverable location--and retrieved it after the wind moved it to where I could get it--1/3 mile away. :D
 
Terry- it probably will some time. I've spent a lot of time this winter on the technical aspects of streamer duration and piston launchers. I'm preparing for Spain this August and don't have the time to publish anything yet. But I'll pull something together afterwards.
 
Just thought I'd give an update of our contest - We did fly the 1/8A Streamer Duration event but I didn't try anything too unconventional. I built two models - a taper paper made from 24# computer paper going up to a 13mm Apogee vac form nose (I was going to use vellum, but I just couldn't get it to roll right) and a 10.5mm straight 3FN with a boat tail. I didn't get the best times because I had trouble with the streamer not wanting to unroll all the way both times, but I did get a deploy, and the combined score was good enough to get me second in the event. Most of the members were glad it was over (most of them hated it), but I thought it was a fun and different event.

BTW - I got my first ever first place finish there in B Egg Loft Duration using a Gassaway Two Minute Egg design. Didn't quite get the two minutes out of it - only 1 minute 40 seconds, but still a respectable time for a newby like myself! :D
 
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