Streamer Duration Plans

Oh calm down Meister, lol, I haven't made any of break throughs. You should know as well as anyone here that it has all been done before and I'm sure there are plenty of others out there who have built lighter than I. It's not a big secret and most of my competitors will see these fly several times before the contest. I was just saving the surprise for the next club launch. That said I,m glad to tell you that I am at 1.62 and 1.63 grams without a motor. For someone like me who tends to over build big fat rockets I think I have them pretty light. So I guess in a way it is a break through, just one of a personal nature. lol

My test model with attached LL has had times above 50 secs. Not in record territory but I'm feeling good about my chances in a regional, IF I can get my piston to work. I still have almost 2 and a half mos to work it out.

I totally agree that this is just a hobby and I have plenty of more important things going on other than building rockets. If I place in competion thats fine. If I get beat by every other flyer there that is also fine. I do intend to acheive my personal best. At the moment I am more excited about the upcoming night launch and and weenie roast. No competion there, unless a hot dog eating contest breaks out.

Peace

That's more like it Jeff.
Sounds like you have a good thing going. Now what seems to be the trouble with your piston? Are you using a straight 0 volumn or a floating head system? Will your RSO's require pistons be enclosed in a tower? in some events where tip off is likely (ie eggloft) some RSO's make guide rails of some sort a requirement with pistons. A pain but easily though with some efficency loss field complyable. Shouldn't be needed with micros but ya never know.

Good question! I assumed that for micro no tower would be needed but that may have been a mistake. I will check with the RSO for a ruling.

I have been working on a piston made from an aluminum rod fixed to a wooden base plate with a fixed head at the top and another fixed centering component about an inch below. The piston slide is a 12" length of T2+ with a fixed stop at the bottom. The stop, Head and centering component are turned from balsa and treated with CA. Everything slides freely with no slop. I am force fitting the engine to the slide with the igniter wires protruding from the top. It seems to be working but I am getting more altitude off of a rod with a LL than I am off of the piston sans LL. Also it is apparent that after several launches the top of the slide is becoming loose and deformed. There are very few drawings of pistons on the net and I'm not sure that I have got the design right. It's 90 miles to the nearest hobby store so I am working with stuff that I have on hand or can get at the local hardware. I have looked at the drawings for your floating head piston with internal wiring and it is an ingenious piece, the parts list is a little intimidating though and the brass pieces are something that I would have to make a trip for.

Plan B is to go with a tower.

Micromeister said:

Our NAR president has said to many, something I try to keep in mind for all Altitude, PD or SD events.
Paraphrasing "NEVER give up a foot of altitude to Frontal area" meaning increased girth to fit an extra inch of streamer or canopy".

Click to expand...

He is NOT correct...this old RoT is being proved out now using advanced cfd flow programs. Real models based on these computer sims are already designed and have been submitted for estimate to a number of cnc machine shops.

Some of these shapes can be eyeballed, but each is slighly different for a particular motor and motor class.

Still, the new shapes will allow flying a larger diameter with LESS drag than their older nose/cylinder cousins.

You will need to learn to mold using fiberglass to take advantage.

The new laminar shapes are flying 30-70% higher on the same motor impulse depending on the config. Exciting work happening behind the curtains folks....!

Kevin K.

kooch said:

He is NOT correct...this old RoT is being proved out now using advanced cfd flow programs. Real models based on these computer sims are already designed and have been submitted for estimate to a number of cnc machine shops.

Some of these shapes can be eyeballed, but each is slighly different for a particular motor and motor class.

Still, the new shapes will allow flying a larger diameter with LESS drag than their older nose/cylinder cousins.

You will need to learn to mold using fiberglass to take advantage.

The new laminar shapes are flying 30-70% higher on the same motor impulse depending on the config. Exciting work happening behind the curtains folks....!

Kevin K.

Click to expand...

The cdf theories & many of the programs your talking about have been around, used and confirmed with pencil and slide rule ages ago...NOT NEW by any means. What is new is that many less tech inclined folks are laying up fibreglass areo shapes at home than every before. Some "newer" shapes are being used now simply because of the ease of access to glass and cdf now, while interesing and very neat if your into that sort of extreme compeititon, these shapes will never be the "Norm" for NAR type competitions..at least not be the masses....all 5200 of us LOL!!!
Many of us "weekend worriers" either do not want or need the Hassle of turning forms and laying up glass for Hobby competition flying.
It is exactly this type of exotic manufactured material "edge" that makes the vast majority of Rocketeers completely turn OFF to competition events.
Not saying the Internat's flyers and other "tinkerers" shouldn't be doing what they can just as mentioned a bit earlier IT's ONLY a hobby.. and no one really gives a flying Rosey Rats Rear end who scored or did what after the event has concluded. All BTC BS...interesting yet not behind the curtains at all.

Micromeister said:

The cdf theories & many of the programs your talking about have been around, used and confirmed with pencil and slide rule ages ago...NOT NEW by any means. What is new is that many less tech inclined folks are laying up fibreglass areo shapes at home than every before.

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Nope. The program (a specific one) we have available now predict both laminar and turbulent flow over a 3-d axissymmetric shape and have ONLY been used as of late last year for mod roc applications. And by only a few people. Parson's shape formulas have only recently been implemented in mod roc applications and a few are now working on shape optimizer programs.

Since when did flying higher become an unworthy goal?

Kevin K.

JPVegh said:

Good question! I assumed that for micro no tower would be needed but that may have been a mistake. I will check with the RSO for a ruling.

I have been working on a piston made from an aluminum rod fixed to a wooden base plate with a fixed head at the top and another fixed centering component about an inch below. The piston slide is a 12" length of T2+ with a fixed stop at the bottom. The stop, Head and centering component are turned from balsa and treated with CA. Everything slides freely with no slop. I am force fitting the engine to the slide with the igniter wires protruding from the top. It seems to be working but I am getting more altitude off of a rod with a LL than I am off of the piston sans LL. Also it is apparent that after several launches the top of the slide is becoming loose and deformed. There are very few drawings of pistons on the net and I'm not sure that I have got the design right. It's 90 miles to the nearest hobby store so I am working with stuff that I have on hand or can get at the local hardware. I have looked at the drawings for your floating head piston with internal wiring and it is an ingenious piece, the parts list is a little intimidating though and the brass pieces are something that I would have to make a trip for.

Plan B is to go with a tower.

Click to expand...

Jeff:
Your micro piston is almost identical to my first attempt at a 0 volumn fixed metal head micro piston awhile back. I started with a section of old 1/8" Stainless steel Launch rod that could be used in any of my standard launcher rod mounting hardward with a fixed brass head in one piece. I'll have to go back to see exactly which size brass tube was used but it gave a very close smooth slide to the 9 to 12 inch long T2+ piston tubes with nothing more then a 3/16" long section of T2 CA'ed as the piston stop. Keep in mind everything added to the slide tube has to be lifted by the motor so keeping all mass down is important.

Over time I've found and had many other flyers report on leaving the igniter leads extrude out over the top edge of the slide tube. MANY have expressed concern this arrangement carries the clips along with the model for some distance before dropping away. On larger thrust motors this isn't as noticable as it becomes on micros. It is SUPER critical that the Launcher igniter lead clips NOT Be in any way tied to the slide tube... (one of the reasons I designed my internal wiring system for most of my other Metal head and floating head pistons.
Sorry I've never really taken any photos of the working parts of these pistons but I will over the weekend.. Hopefully I'll have something to show on Monday. While I'm not sure if the Mil-max connectors will work with a fixed metal head micro piston It might? I'm 99.9% sure dragging your clip leads is what's adversely affecting your piston model launches.

One way to "help" limit igniter wire lead dragging is to use .050" holes about 1/4" below the top of your slide tubes on each side to "thread" the igniter wires into on each side of the piston. Trust me when I tell you this set up works well but can be very frustrating on the field during competition. Getting the leads into the holes without dislodging the igniter from the prepped model/motor can be nerve racking and almost painfully slow. The Joy is, this method does NOT clamp the nichrome wire between the motor casing and the slide tube so as soon as the model begins to move the broken wires can slide through the fairly loose holes. I personally have had much better luck using holes spaces about 80°-90° apart located toward me rather then 180° apart on the sides of the slide tube. Others I've seen use slits but I've never been able to get a good seal between model motor and slide tube with that method.

If some form of "tower or rail" guide is required. as can be seen in the photo below one can easily add 3 or 4 (depending on fin setup) very thin, light weight spars of Styrene, split Bamboo, or Carbon fiber rod. The ones in the photo were field applied to this particular slide tube as the particular RSO for whatever event we were flying was concerned about piston tip off. Most have since "Seen" that Micro's are SO quick off the pad the guides are unnecessary no longer requiring use. I have set-up a couple T2++ slip-on with carbon fibre rod rail guides that I carry with the floating head piston just in case some RSO has a problem. They would difinately hamper the performance of my piston but if everyone has to use some from of tower i'd feel the field would be about level
Hope this helps a little, I'll try to get some additional info an pic soon.

All good stuff Micro, Thanks.

The slide itself is very light weight just having the T2+ and a small balsa stop but carrying the weight of the ignitor clips and wires has to be adding considerable weight/resistance. I suspected this might be where my problem lay. I have tried bunching about a foot of wire at the base to relieve the resistance but it does nothing to help with the weight.

The more complicated this piston gets the more inclined I am to scrap it and just concentrate my efforts on a tower. In fact I need to try some launches from a tower anyway to see how it compares to the other methods already tried. So far my very best times have been with a pop lug.

I talked to the RSO and he seemed skeptical about launching off of a piston alone. He said he MAY allow it with some additional stand off distance. It's not exactly the definitive ruling I was hoping for. If I go this route I may have to do some demonstration launches prior to the event. One way or another having a tower ready seems prudent.

Thanks again

kooch said:

Nope. The program (a specific one) we have available now predict both laminar and turbulent flow over a 3-d axissymmetric shape and have ONLY been used as of late last year for mod roc applications. And by only a few people. Parson's shape formulas have only recently been implemented in mod roc applications and a few are now working on shape optimizer programs.

Since when did flying higher become an unworthy goal?

Kevin K.

Click to expand...

Kevin:
The key word in your statement above is "in mod-roc applications". That is just not completely correct or accurate, Many of us have been using CFD prorams for more than a decade both professionally and in the hobby. Not necessarly widely known nor have many of the more exotic model shapes actually been produced but they have been "seen" for some time now. These Programs have at least til now been exceedingly expensive and high end computer hardware hogs. Perhaps this has changed...that will certainly be a very good thing
Not saying there may not be some looking to go Higher but to many of us the FACT is flying higher is NOT always the ultimate goal. I know personally unless i'm looking at a specific Alititude event I don't care one bit about altitude. Plenty of competition flyers have little or no intrest in spending a hundred bucks or more tied up in Programs, mandrels, molds and materials to win a 5 dollar trophy. Most prefer to.. and I among them will stick with Paper Tiger and Taper Paper type compeitition models til it becomes ecocomically adventagous to me to do something else. Perhaps in time some smart fellow will develope a method of obtaining these exotic Laminar flow designs without the need for super expensive mandrels and specialty materials.

Wonderful news that new flow dynamic shape program components are being added to our tools, should be of great help to our internat flyers.. just not all that big a deal for the masses.. that is the other 5300 or so nar flying membership let alone the couple hundred thousand who've never heard of any mod-roc national org. Exciting stuff for a very limited few... not so much for the rest of us.

Super info; Thank you for sharing the good news! Hope to see or hear about some evidence of what you've suggested at up-coming Nar or International everts. Perhaps more visual evidence might inspire more innovation??

JPVegh said:

All good stuff Micro, Thanks.

The slide itself is very light weight just having the T2+ and a small balsa stop but carrying the weight of the ignitor clips and wires has to be adding considerable weight/resistance. I suspected this might be where my problem lay. I have tried bunching about a foot of wire at the base to relieve the resistance but it does nothing to help with the weight.

The more complicated this piston gets the more inclined I am to scrap it and just concentrate my efforts on a tower. In fact I need to try some launches from a tower anyway to see how it compares to the other methods already tried. So far my very best times have been with a pop lug.

I talked to the RSO and he seemed skeptical about launching off of a piston alone. He said he MAY allow it with some additional stand off distance. It's not exactly the definitive ruling I was hoping for. If I go this route I may have to do some demonstration launches prior to the event. One way or another having a tower ready seems prudent.

Thanks again

Click to expand...

Are you guys flying in a NEW Section or prefect? Bare Pistons have been allowed in NAR competitions for decades. GENERALLY the only time towers or extra guides are required is with very Heavy slow liftoff models Like Egglofters or lower thurst Payload Altitude models.

Back to the Micro Pistons:
I'm sure your T2+ piston slide is light but if our .284Ns motors are required to break away for a set of copper microclip leads by carring them to the end of the slide tube travel you've lost all the advantage gained by using the piston in the first place.. which is that first initial puff of energy as the motor starts.

Back in 2001 when I first started playing with Micro pistons the Plug-in systems I'm using now wasn't available. Initially I like you went on the assumption that trapping the igniter between motor casing and slide tube body would work just as well as it has for decades with other thurst motors. unfortunately it does NOT. We've discovered all that extra weight from the wires and clips completely eliminates the advantage gained.
That is EXACTLY why I started working on an INTERNAL wiring system to eliminate as much of this problem as possible. As it turns out it also makes for better larger thurst motor pistons as well.

Below is a close up of the 1/4" thin wall brass tube "metal head" from my original 0 volumn micro piston. That's all there is to it a 1-1/2 to 1-5/8" piece of Brass tubing with an old 1/8" stainless steel launch rod centered in side it by wraps of masking tape embedded in 30 minute epoxy.
Had I thought about it just a little I could easily have insulated and installed a couple 1/16" brass tubes inside the brass tube above the support rod with solder 22 ga or smaller lead wires. twisted and taped to the lower end of the support rod. This would have allowed an igniter to be fashioned to fit inside the smaller tubes making contact. This system was used for awhile in many of my larger 13mm, 18mm and 24mm motor pistions. With the discovery of small positive contact circuit board sockets like the Mill-Max sockets many of the contact and continuity problems went away.
Until this brass tube socket evolved we were forced to drill slightly larger holes in the slide tubes about 1/4" below the forward edge of each slide tube. These holes allowed the bare nichrome igniters to be inserted and positioned to allow the model/motor to be inserted and lowered onto the slidetube without shorting or effecting continuity with the clips remaining below and beside the piston tube. At ignition the slightly oversize holes allow the scrap ends from the igniter to slip out rather then be carried up as the model/tube slide forward. This process worked well "MOST" of the time. Occasionally a lead caught an edge foiling the piston launch.

First attempt at adding light weight guides to micro pistons was with thin wall styrene tube. It was also believed that 3" long guides were needed. This has also been Proven time and again to be totally unnecessary, with 1" or 1-1/4" long guide rods being more then sufficent at the high speeds attained by our micro models.

around 2004 I started fooling around with floating head pistions. First with
Telescoping 1/16" & 3/32" brass tubing later graduating to circuit board slip pin sockets.. then Mill-Max sockets.
To get a very light weight floating head for use with Micros I needed to get the socket size to fit inside our close fitting T2 craft tubing. with just a little dremel work and a rather funny tape construction method I succeded it getting the thing to work smoothly and efficently completely eliminating the continuity problems found with the telescoping tube igniters.
The only real headache is reducing the smallest close fitting brass tube (7/32"OD) to slide freely inside our T2 stops .220" ID. I found that hand tapering with an electric drill and 120grit to 600grit sandpaper, these support tubes trimmed from .21875 to about .1990" where they worked out just fine. Takes awhile to get the taper down right but once done these support tubes last indefinitely.

Preparing for a couple micro contests I wanted to be completely prepared should there be any question concerning model tip off from one of my micro pistons but didn't want to permanently add guides to the slide tubes as was done on the original metal head piston slide tube.

Instead I went with a very short section of T2++ slide over tubing and 3 or 4 one inch long .050" Carbon fibre rod pieces I had laying around Ca'ed to the sleeve. This produced a couple very light weight "Tape on" towers that can be added to my slide tubes if absolutely necessary at any time. They do effect performance a bit, as they do have some mass and resistance but I felt if everyone were being made to use a tower around their pistons I wouldn't be hampered too much. As it turned out all the RSO's agreed that these micro models get going so quickly no additional guidance would be required. Still Be Prepared is the Scout motto
Another suggestion was to use bamboo skewers, the very thin 1/16" ones. Well: as they come whole they are really too heavy and bulky for my taste. Split they may make a decent add-on tower if needed.

Over the last couple years I've also been playing around with the required length of the slide tubes for both Metal head 0 volumn and Floating head pistons.
I've had very nice results with slide tubes ranging from 9" to as long as 12" at the max. The heavier the launching vehicle the longer the slide tube needs to be with the heaviest model getting up to speed easily. Longer lengths seems to reduce achieved altitiude.
Hope all this helps.

Micromeister said:

Are you guys flying in a NEW Section or prefect? Bare Pistons have been allowed in NAR competitions for decades. GENERALLY the only time towers or extra guides are required is with very Heavy slow liftoff models Like Egglofters or lower thurst Payload Altitude models.

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Our section has been around a while but until the last few months, we have never had or participated in any competitions. We knew of towers and pistons in a vague, distant sort of way but none of us had any experience with them.

The RSO did not nix the idea. He only wanted to gather some more info to make sure things were done in a safe manner. That is, after all, the responsibility that goes with the position.

Its moot now. He let us know yesterday that pistons would be fine for anything except the heavy/slow stuff you indicated above. I think he made a good call. He was not prepared to rule on the matter until he had enough info to do so in an informed manner.

I'm glad he gets to make the calls now instead of me.:cyclops:

JAL3 said:

Our section has been around a while but until the last few months, we have never had or participated in any competitions. We knew of towers and pistons in a vague, distant sort of way but none of us had any experience with them.

The RSO did not nix the idea. He only wanted to gather some more info to make sure things were done in a safe manner. That is, after all, the responsibility that goes with the position.

Its moot now. He let us know yesterday that pistons would be fine for anything except the heavy/slow stuff you indicated above. I think he made a good call. He was not prepared to rule on the matter until he had enough info to do so in an informed manner.

I'm glad he gets to make the calls now instead of me.:cyclops:

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10-4 John:
Exactly why I ask. I've run into this situation at a couple away contests over the years usually with new RSO's or in new competing clubs. Glad to hear you folks have found good council and RSO training.

Micro, WOW! This is all very helpful stuff. I can really appreciate the many hours of thought and developement you have put into these micro pistons. It is interesting to see that my progress is similar to your own earlier experiences. I am not sure that I would have gone on to find the solutions that you have come up with. I am thankful for the benefit of your experience here. Thanks for taking the time to post the info and the pics.

To be honest I was about to scrap the idea of using a piston but now I think I will try to build your floating head design.

As JAL has indicated our RSO has approved the use of piston only launches for most of the events in our upcoming competiton. So I may also be working on 13mm and 18mm pistons soon. 2 months seems like a long time but I know it will go by quickly and there just aren't enough hours in the day for all of this building and testing. With that In mind if I have to choose one event to concentrate my efforts on it will be 1/8A SD.

Laissez les bons temps rouler!

JPVegh said:

Micro, WOW! This is all very helpful stuff. I can really appreciate the many hours of thought and developement you have put into these micro pistons. It is interesting to see that my progress is similar to your own earlier experiences. I am not sure that I would have gone on to find the solutions that you have come up with. I am thankful for the benefit of your experience here. Thanks for taking the time to post the info and the pics.

To be honest I was about to scrap the idea of using a piston but now I think I will try to build your floating head design.

As JAL has indicated our RSO has approved the use of piston only launches for most of the events in our upcoming competiton. So I may also be working on 13mm and 18mm pistons soon. 2 months seems like a long time but I know it will go by quickly and there just aren't enough hours in the day for all of this building and testing. With that In mind if I have to choose one event to concentrate my efforts on it will be 1/8A SD.

Laissez les bons temps rouler!

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As always; Anything I can do to Help Micro Maxx rocketry along I'm more then happy to do. The more folks we can get Flying Micros the better it is for this side of the Hobby.

Do you have the Floating head piston drawing with all the part numbers and sizes? I'm pretty sure the pdf file is available from the equipment files section on the MicroMaxRockets yahoo group. I may also have uploaded a Jpeg version sometime ago here?

I seem to recall doing a 13, 18 & 24mm metal head piston pictorial build a couple years back. I think it should be in the Archive TRF-1 files perhaps. If you need any help when you get around to them let me know I still have the pictures and perhaps a Club newletter article on piston production? It's been awhile.

Micromeister said:

As always; Anything I can do to Help Micro Maxx rocketry along I'm more then happy to do. The more folks we can get Flying Micros the better it is for this side of the Hobby.

Do you have the Floating head piston drawing with all the part numbers and sizes? I'm pretty sure the pdf file is available from the equipment files section on the MicroMaxRockets yahoo group. I may also have uploaded a Jpeg version sometime ago here?

I seem to recall doing a 13, 18 & 24mm metal head piston pictorial build a couple years back. I think it should be in the Archive TRF-1 files perhaps. If you need any help when you get around to them let me know I still have the pictures and perhaps a Club newletter article on piston production? It's been awhile.

Click to expand...

Yes sir I do have the drawing from the MMX forum and I've spent several hours today reviewing the archives. I've found alot of good info. I just need to order a few things to get started.

Thanks again

I've been turning a 7/32 brass tube on my electric drill for about 30 minutes now using 150 grit. I've knocked off about 1/1000 of an inch. This is gonna take a little longer than I thought lol.

JPVegh said:

I've been turning a 7/32 brass tube on my electric drill for about 30 minutes now using 150 grit. I've knocked off about 1/1000 of an inch. This is gonna take a little longer than I thought lol.

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yes it does indeed LOL!!!! I did 8- 12" long lengths during the design phase building. My hands looked like I'd been guilded before I was done.
It's possible to speed the process up a little by using 120grit for the heavy metal removal, then removing the scratches with 220, 320 400 and finally 600girt to repolish the surface. You will be wearing out a few sheets of Sandpaper, not to mention your finger tips from the friction LOL!!!

It will also help to have a few 2" long pieces of Clean, new, unstretched T2 tubing to test the fit and smoothness of the support tube(s). The T2 tubing should glide freely to about 1" of the base of the support tube.

It didn't take long to figure out that leather gloves are a good idea. I decided that a paper mask might be a good idea as well after a blast of air from the drill blew some brass dust into my face. Face fitting goggles would also be good idea unfortunately all I have are safety glasses. I may hold off on going any further until I can get some goggles. I know from experience that metal dust in the eyes is no fun.:no:

Yeah, I'm a pretty impatient guy, it didn't take long before I broke out the 100 grit. I'm down to .212" now and the T2 slides easily with just the light pressure from one finger. Should I have a totally frictionless fit? Should the T2 slide on its own if the brass is tipped up and down? I'm prepared to go all the way down to .199" but want to maintain as much wall thickness as possible.

Thanks

JPVegh said:

\
Should I have a totally frictionless fit? Should the T2 slide on its own if the brass is tipped up and down? I'm prepared to go all the way down to .199" but want to maintain as much wall thickness as possible.

Thanks

Click to expand...

Wall thickness is not a problem at .199". Yes! when inverted the T2 should slide effortlessly off the brass tube.