Ye Olde Rocket Forum - How long does a Model Rocket last?

traveler

08-01-2009, 01:02 AM

BEC

08-01-2009, 01:33 AM

I'll be interested to see the more recently experienced answers to this. Projecting the condition of my most-flown model since I became a BAR (a simple Semroc Boid which is currently up to 15 I think) I'd have to say that 100 flights is quite feasible. Doing repairs/maintenance as needed and not crashing should lead to literally hundreds of flights I would think. The trick would be replacing a dying shock cord before it failed, for example, and making sure the fins are secure after any hard landing and fixing as needed.

I suppose it could get to the point of the old joke about George Washington's original hatchet (though the handle's been replaced five times and the head four times) or some such...but that's a bit extreme. :)

Royatl

08-01-2009, 02:01 AM

The assumption here is that the Rocket is always launched and recovered successfully, launch after launch. Never a crash or mishap.

With that being said: How long does a Model Rocket last (to be flown again)?

I am thinking of the heat from the engine, especially the ejection charge. Does the inside of the tube eventually deteriorate from the heat? The components? Shockcord? And how about shock and stresses? Do parts crack or lose shape over time?

What would be the maximum number of launches before a Rocket would "break" on the next launch?

:confused:

Yes, heat damage does occur. Yes, paint and glues age, shrink and crack over time. Paper tubes can get damaged by humidity and mold. Balsa generally holds up pretty well, except where influenced by paint. or weathering. And flight stresses can take a toll.

How long they ultimately last depends on how much TLC you are willing to apply to any particular rocket. The best verifiable record AFAIK goes to Jim Flis's Estes Sprint (at least I remember it being a Sprint), that he kept going for 500 flights, the 499th flight being launched by Gleda Estes and the 500th flight launched by Vern Estes at NARAM 47 in Cinncinatti, after which he gave the rocket to Vern. Jim can best tell you what he had to do to keep it flying for that long.

Vern's original Big Bertha (built in ?? 1962 or 1964??) may have more flights than that and it is still flying, at least as lately as a year ago at NARAM 50.

I have an Estes SPEV that I've kept going for over 200 flights since it was built in the mid 70's (lost exact count a few years ago). It has had severe nose cone and transition dents that were filled, engine mount and a balsa transition replaced after hanging on a power line for a week, fins all re-attached at least once, and one fin eventually replaced. Repainted twice, around the original decals. That's not to mention five or six recovery system replacements.

garmtn

08-01-2009, 02:04 AM

I built a "screaming eagle" a few years ago, and launched maybe 6 times. Not one of my better paint jobs but, still have it. The end of BT that nosecone goes into is starting to get soft. To say it will last a 100 flights is ludicrous! With this one, I'll keep launching till it's dead or gets lost. Otherwise a good rule of thumb is 6-10 times then retire it or sacrificeto the "rocket tree god." Glenn NAR89197 ;)

Mark II

08-01-2009, 02:09 AM

Well, each one of mine lasts until I build a new one that I want to fly more. And most of the time I'm building new ones. Flying a rocket many dozens of times without losing it or damaging it beyond repair is no small feat, requiring:

excellent components in the kit and decent skills in assembling it
luck
access to wide open, flat, treeless flying fields
a big box of luck
having lots of eyes on hand to help you track it every time you launch it
luck in spades
using only fresh motors that have good, cato-free track records
an abundance of fortuitous chance
consistently good, low wind conditions and excellent visibility when you fly it
consistent good fortune
conservative (but not too conservative) motor choices
winning the luck lottery
always insuring that the recovery system is in good condition and packed correctly
a heapin' helpin' o' luck
proper storage of the rocket at home and suitable protection of it during transport to and from launches
beaucoups de chance
A whole host of things other than the factors you list can bring an end to the flying record of a rocket. Most of them are much more likely to come into play, and much sooner, than the types of things that you talk about. IOW, "stuff" happens. At least they do with my rockets, anyway. :rolleyes:

MarkII

Mark II

08-01-2009, 03:29 AM

None of the rockets that I had in my early rocketry period in the mid to late 1960's have survived. The oldest rockets that I have are several Micromaxx and mini engine-powered cardstock saucers and pyramids designed by Art Applewhite that I built in early 2004, shortly after I became a BAR. I also have several Micromaxx-powered Bic Stic rockets that I built from plans that I downloaded from Art's site. I have flown some of the Micromaxx saucers and Qubits as much as a dozen times (I haven't kept an exact count), yet they show very little wear (just some soot around the ejection charge ports). After I built each one of them, I sealed the cardstock with 2-3 coats of clear coat to protect them from humidity, and I keep them on a rack on a desk away from any windows and out of the sun when I am not flying them.

My mini-engine powered cardstock saucers and Qubits are flown with Estes A10-PT plugged engines (when I can still find them) and so they never get exposed to ejection charges at all. All of these rockets fly low and slow, so they are always easily tracked and recovered, and they have no recovery systems that need to be replaced. I haven't flown my Bic Stic rockets as much, but they are made of materials that will not break down from exposure to the ejection charges of Micromaxx engines.

Unless I lose them or leave them out in the rain, none of these rockets are ever likely to wear out from being flown. The cardstock Micromaxx and 13mm saucers and Qubits and the Bic Stic rockets can probably survive as many as a thousand flights or more. I also have several larger Art Applewhite rockets (up to a 38mm Cinco) that fly on plugged black powder or composite propellant motors, and these can theoretically be flown indefinitely, too. Because of their size, though, the largest ones naturally land a smidgen harder than the micros, but the only time that any of them would be damaged would be if they landed in the lake.

I also have a number of Micromaxx rockets built from kits by FlisKits and ASP. Because they are so small and fly so high, I usually only launch them if I have exceptional visibility or when I can have help with tracking them, so I don't launch them as often. They are not quite as indestructible as the cardstock rockets, but they are close. Micromaxx motors put very little stress in most of the rockets that are built for them, so these kit rockets can potentially survive many hundreds of launches.

MarkII

jflis

08-01-2009, 06:21 AM

How long they ultimately last depends on how much TLC you are willing to apply to any particular rocket. The best verifiable record AFAIK goes to Jim Flis's Estes Sprint (at least I remember it being a Sprint), that he kept going for 500 flights, the 499th flight being launched by Gleda Estes and the 500th flight launched by Vern Estes at NARAM 47 in Cinncinatti, after which he gave the rocket to Vern. Jim can best tell you what he had to do to keep it flying for that long.

That was a fun one, actually :) You can see the photo album of that model and its 500th flight here: http://fliskits.com/photo_album/2005/naram47/index3.htm

I built it in 1973 and got those 500 flights over 32 years. The fins, body, engine mount, nose, paint and decals were all stock (original). The streamer and shock cord got replaced a few times over the years and I think the launch lugs got replaced once.

The body tube suffered the most (of the original parts) and there were a few times I had to seal up the spiral with some CA. Other than that it really heal up quite well...

tfischer

08-01-2009, 09:39 AM

I have about 6-7 rockets from my original kid-stint as a rocketeer (mostly early 80's, with a few around 1990 when I was in college and a few of us made/flew some one May term). All of them held up perfectly except for the shock cords, which are now repaired, and all are in flyable condition today, save for one I flew last launch and had a mishap (but it will fly again after repairs).

The only other issue I had was the parachute shroud "discs" didn't hold up on many of them. So I just cut little pieces of black electrical tape and all was well again...

Now as to how many flights you can get out of a single rocket, that's another question. But time-wise, they should last a LONG time...

-Tim

JoeLaunchman

08-01-2009, 07:46 PM

Another, more esoteric, question in this discussion is: When is the same rocket no longer the same rocket? If you replace the parachute, shock cord, shock cord mount, nose cone , and engine mount, and replaced a couple of broken fins, can you still count it toward the total number of flights for that rocket?

It's like the cliche about "Grandpa's Hammer." Well sure, he's replaced the handle 3 or 4 times and he's replaced the head 3 or 4 times, but it's still the same old hammer he's always had...or is it?

Royatl

08-01-2009, 08:10 PM

It's like the cliche about "Grandpa's Hammer." Well sure, he's replaced the handle 3 or 4 times and he's replaced the head 3 or 4 times, but it's still the same old hammer he's always had...or is it?

Yea, but our bodies essentially get replaced every year, so are we not the same person as we were last year?

LeeR

08-01-2009, 08:14 PM

I had a rocket with dual 24mm mounts in a BT-70, and after about 15 years, the motor tubes were crumbling, they had badly corroded. I've never flown anything that lasted that long, and it could still be flown, it is just a little ragged at the ends of the motor tubes and body tube.

My oldest rocket is an Estes Saros, which I built around 1976. It has not been flown in 15 years, and I see no reason to tempt fate. It is a nice rocket to just keep on the bookcase with the younger ones.

Bob Kaplow

08-01-2009, 10:58 PM

That was a fun one, actually :) You can see the photo album of that model and its 500th flight here: http://fliskits.com/photo_album/2005/naram47/index3.htm

I built it in 1973 and got those 500 flights over 32 years. The fins, body, engine mount, nose, paint and decals were all stock (original). The streamer and shock cord got replaced a few times over the years and I think the launch lugs got replaced once.

The body tube suffered the most (of the original parts) and there were a few times I had to seal up the spiral with some CA. Other than that it really heal up quite well...

I was going to mention Jim's Sprint but he beat me at it. That's the most I'm aware of for one rocket.

One of my happy meal conversions made it to about 190 before I had to retire it. There wasn't enough plastic left for the duct tape to stick to.

I've actually got a competition A RG that has eeked out about 3 dozen flights. Last one spent 3 hours floating in a pond before it was recovered. And an A HD model that's not far behind, and has collected about half a dozen NARAM trophies along the way, in spite of twice being lost overnight and returned the next day. Some competition models DO get to make a lot of flights.

Mark II

08-02-2009, 05:14 AM

My parents tossed my original fleet of Estes rockets, supplies and launch equipment from my first stint as a model rocketeer in the mid to late '60's into the trash as soon as I was safely out the door and off to college, before my bed had even gotten cold. And they did so without telling me about it. That is why I have nothing but memories from those days. It is just one example of the kind of "other factors" that limit the lifetime of many rockets. It often isn't wear and tear that brings them down; quite often it is some non-rocketry event or series of events that does it. This has proven to be the case with nearly all of my rockets during both of my stints in the hobby, from 1967 right through to the present day.

MarkII

garmtn

08-02-2009, 08:16 AM

To bad. Although a factor, now u have incentive to start a new fleet. I've discovered with a new initiative, more creativity can abound! Good Luck! ;)

Nuke Rocketeer

08-02-2009, 09:33 AM

I built a Cherokee D during my first BARdom in 1982 that had over 200 flights on it before it floated off to Nirvana in 2004. It still had the original fins and nose. The paint was really faded and the decals were tattered, but the tube was still in fairly good shape.

I hated losing that one...

Mark II

08-02-2009, 09:42 PM

To bad. Although a factor, now u have incentive to start a new fleet. I've discovered with a new initiative, more creativity can abound! Good Luck! ;)
Oh, that happened a very long time ago, back in 1972. But that is an example of why some rockets don't last very long! :chuckle: And it is why I don't have anything from my early days in the hobby. I have been building a new fleet since 2004. :D

MarkII

Bob H

08-02-2009, 10:14 PM

When I moved out of my parents house I took all of the unbuilt kits, motors, and parts with me.

I also took some of the built kits and I had intended to come back for the rest at a later time.

A while passed and I went back for the rest of them and found that my younger brother had decided that since I hadn't taken them with me, that it was alright if he launched them.

His idea of launching rockets was to put the largest motor that would fit and then launch them from my parent's back yard (about an acre).

Needless to say, most of them only lasted one flight.

traveler

08-08-2009, 03:02 PM

I appreciate everyone's reply.

Yes, heat damage does occur. Yes, paint and glues age, shrink and crack over time. Paper tubes can get damaged by humidity and mold. Balsa generally holds up pretty well, except where influenced by paint. or weathering. And flight stresses can take a toll.

[snip]

Repainted twice, around the original decals.

[snip].
Is there something to spray coat the inside of a body tube to make it more durable? Does anybody do that? Is there a good coating for the outside?

[snip] .... The trick would be replacing a dying shock cord before it failed, for example, and making sure the fins are secure after any hard landing and fixing as needed.

[snip]
What are the early signs of a soon-to-fail shock cord?

I built a "screaming eagle" a few years ago, and launched maybe 6 times. Not one of my better paint jobs but, still have it. The end of BT that nosecone goes into is starting to get soft. To say it will last a 100 flights is ludicrous! With this one, I'll keep launching till it's dead or gets lost. Otherwise a good rule of thumb is 6-10 times then retire it or sacrificeto the "rocket tree god." Glenn NAR89197 ;)
Why did the end get soft? Defective body tube? Bad landings? Something else?

Good advice Mark II. Thanks!

I had a rocket with dual 24mm mounts in a BT-70, and after about 15 years, the motor tubes were crumbling, they had badly corroded. I've never flown anything that lasted that long, and it could still be flown, it is just a little ragged at the ends of the motor tubes and body tube.

My oldest rocket is an Estes Saros, which I built around 1976. It has not been flown in 15 years, and I see no reason to tempt fate. It is a nice rocket to just keep on the bookcase with the younger ones.
Were the motor tubes made fom a defective material? Is there something that can be used to coat motor tubes?

That was a fun one, actually :) You can see the photo album of that model and its 500th flight here: http://fliskits.com/photo_album/2005/naram47/index3.htm

I built it in 1973 and got those 500 flights over 32 years. The fins, body, engine mount, nose, paint and decals were all stock (original). The streamer and shock cord got replaced a few times over the years and I think the launch lugs got replaced once.

The body tube suffered the most (of the original parts) and there were a few times I had to seal up the spiral with some CA. Other than that it really heal up quite well...
Nice! Great! The Original Body Tube! Any special coatings or such on it?

:cool:

LeeR

08-08-2009, 04:24 PM

1. Is there something to spray coat the inside of a body tube to make it more durable? Does anybody do that? Is there a good coating for the outside?

2. What are the early signs of a soon-to-fail shock cord?

3. Were the motor tubes made from a defective material? Is there something that can be used to coat motor tubes?

1. I'd find long-handled swabs and coat the inside with CA, all the way downto the motor mount. But at the rate I fly, I do not imagine a need to do this for any of my rockets.
:)

2. If it is visual, like soot or charring, that's pretty obvious. If it starts losing it stretchiness, it is starting to break down. I use metal fishing line leaders anchored to the motor mount, and bring them up close to the top of the tube. If they have a swivel, I remove that, and install a small split ring (like you put keys on). Then I can tie the sock cord to this, and then to the nose cone, optionally adding a swivel there, if you want. Makes shock cord replacement easy. I never glue a shock cord directly to the body tube, such as with the fold-up style typcially found on kits. Much easier to add a pre-made leader, and you can find these in 6, 12, and 18 inch lengths at Walmart with the fishing equipment.

3. I'd say I should have wiped off as much of the residue after flight. I'm sure it was the corrosive effects of the motor exhaust.

dwmzmm

08-08-2009, 05:37 PM

I've got models built since 1969 that have lasted up through this day.....many built in 1970 or so are still on my active fleet.....

Mark II

08-11-2009, 05:24 PM

One sign of premature heat-induced wear on an elastic shock cord is stiff or hard spots spaced along the length of the cord. These are caused when too much heat from the ejection charge reaches one end of the shock cord bundle while it is still in the body tube. Since the cord is usually coiled up, excessive heating applied to the lower end of the coil produces characteristic damage at relatively evenly-spaced intervals along part of the cord's length. These hard spots will never get any better and one of them will eventually be the site where the cord separates. An elastic shock cord that is in good shape will be strong and stretchable along its entire length with no visible damage and no hard spots.

Another warning sign is overall browning of the shock cord (as opposed to just small black or gray soot spots). The cord should immediately be replaced if you see this, because it will definitely break on the next flight. As mentioned, a few small and scattered black or gray soot spots are usually OK, but if the cord has extensive areas of them, that is also a warning sign.

I see these two signs most often on 1/8" flat elastic shock cords. It is tempting to use that size of elastic because it can be easily packed into the smaller sizes of body tubes, but it is easily damaged by ejection charge heat. If you can fit it in and are reasonably sure that it will deploy, use 1/4" elastic instead. This size is fine for anything from BT-55 to BT-80 sized tubes. For BT-50 and BT-20, you can use oval elastic, but make sure that the piece you use lies flat and has no permanent twists in it when you roll it out onto a table. There are other materials that can be used for shock cords, too, but that would be fodder for a completely new discussion thread.

MarkII

Jeff Walther

08-12-2009, 03:53 PM

Is there something to spray coat the inside of a body tube to make it more durable? Does anybody do that? Is there a good coating for the outside?

I haven't tried it, but you could try Rustoleum's high temperature spray paints. I know they have a flat black. I think they also make a kind of rust orange. The chrome was discoloring and scratched on motorcycle pipes, so I stripped them thoroughly and painted them black with the black Rustoleum (my MC is black) high temp paint and it has lasted about 20 years now. My pipes aren't shiny, but they just kind of fade into the motorcycle background.

jetlag

08-13-2009, 04:46 AM

As Lee said earlier, thin CA is a great 'coating' to use on the inside to strengthen body tubes if you sense a problem with longevity issues. I dribble a little in and wipe it around with a wood-sticked cotton swab. You can also dribble some in and twirl the BT aroun to spread the glue (for long BT's). Medium CA works well also and allows you a little more time for the procedure. Again, as has been said, this is really not necessary for most rockets, but it won't hurt anything to do; it won't add very much weight (depending on the size of the BT). Just remember more CA is not necessarily better.

When I do it, I only use CA (or epoxy) to coat around the BT area just forward of the engine mount to protect the BT from the hot gases as they exit the top of the motor. I may also use a little CA around the forward opening of the BT to help wear protection from the nose cone and recovery; this helps keep the BT paper layers from fraying and delaminating as the # of launches increase. This is especially helpful if you are restoring an old rocket, and the forward end of the BT is worn.
Hope this helped!
Allen

Jeff Walther

08-13-2009, 12:23 PM

As Lee said earlier, thin CA is a great 'coating' to use on the inside to strengthen body tubes if you sense a problem with longevity issues.

My experience is that CA causes some shrinkage in body tubes which are treated with it.

jetlag

08-13-2009, 01:35 PM

My experience is that CA causes some shrinkage in body tubes which are treated with it.

I have never experienced shrinkage due to the use of CA this way(cold weather, maybe :rolleyes: ).
I don't use accelerator for this application; perhaps this is the shrinkage cause you experienced? The chemistry of cyanoacrylates does not really lend itself to shrinkage. Perhaps a slight buildup of material is definitely possible, though, which might mimic 'shrinkage,' as the interior wall of the BT fills with CA.
Some of the surgical CA's might shrink slightly, but I do not know. The material we use here at the Heart Center does not shrink.
Allen

traveler

08-13-2009, 02:33 PM

Good to see more information on rocket longevity being posted.

1. I'd find long-handled swabs and coat the inside with CA, all the way downto the motor mount. [snip]
I just spotted that very technique in a rocket building techniques website by Chris Michielssen. He does only the tube ends though.

http://www.howtobuildmodelrockets.20m.com/BuildingTipsStartKitPage3.html

I haven't tried it, but you could try Rustoleum's high temperature spray paints. I know they have a flat black. I think they also make a kind of rust orange. [snip]
That's interesting. (On a separate thought: I think that's the color needed for the external fuel tank on my upcoming space shuttle build.)

[snip]

When I do it, I only use CA (or epoxy) to coat around the BT area just forward of the engine mount to protect the BT from the hot gases as they exit the top of the motor. I may also use a little CA around the forward opening of the BT to help wear protection from the nose cone and recovery; this helps keep the BT paper layers from fraying and delaminating as the # of launches increase. This is especially helpful if you are restoring an old rocket, and the forward end of the BT is worn.
Hope this helped!
Allen
Those are the exact two places I had in mind when I first started this thread, engine heat and BT end wear. You only coat just forward of the engine though?. Wouldn't the same heat go all the way up the tube?

:cool:

Jeff Walther

08-13-2009, 03:28 PM

I have never experienced shrinkage due to the use of CA this way(cold weather, maybe :rolleyes: ).

I don't use accelerator for this application; perhaps this is the shrinkage cause you experienced? Perhaps a slight buildup of material is definitely possible, though, which might mimic 'shrinkage,' as the interior wall of the BT fills with CA.

I don't use accelerator either. The build-up hypothesis is possible though. I treated the engine tubes in my cloned Midget and afterwards, I could not get engines into the thing. It took a lot of work with a rolled up piece of sand paper before engines could be inserted again.

Mark II

08-13-2009, 07:15 PM

I don't use accelerator either. The build-up hypothesis is possible though. I treated the engine tubes in my cloned Midget and afterwards, I could not get engines into the thing. It took a lot of work with a rolled up piece of sand paper before engines could be inserted again.
If you treat the insides of motor tubes with CA, that will happen. The reason is not that it causes the tube to shrink, but rather that it causes the tube wall to swell slightly. The solution is simple: sand the tube after you have treated it with CA. It will sand very easily. Treating paper parts with CA is actually a common technique for making them sandable; once the paper has been impregnated with cyanoacrylate, it can be sanded without getting shredded, like untreated paper would do.

Sanding the inner wall of a paper tube in order to increase the ID is hard, tedious work under any circumstances, even if no CA is involved. Been there.

MarkII

jetlag

08-14-2009, 03:57 AM

If you treat the insides of motor tubes with CA, that will happen. The reason is not that it causes the tube to shrink, but rather that it causes the tube wall to swell slightly. The solution is simple: sand the tube after you have treated it with CA. It will sand very easily. Treating paper parts with CA is actually a common technique for making them sandable; once the paper has been impregnated with cyanoacrylate, it can be sanded without getting shredded, like untreated paper would do.

Sanding the inner wall of a paper tube in order to increase the ID is hard, tedious work under any circumstances, even if no CA is involved. Been there.

MarkII

Ditto!

Jeff Walther

08-14-2009, 11:27 AM

If you treat the insides of motor tubes with CA, that will happen. The reason is not that it causes the tube to shrink, but rather that it causes the tube wall to swell slightly.

Ah, thank you for the explanation. Needless to say, I resolved never to do that again. :-)

However, wrapping the sand paper around the handle of a no.1 handle Xacto knife makes it not-too-painful to sand the inside of a BT-5 engine tube. A larger engine tube would have been a much bigger pain--although if it had been a BT-20 I could have just resolved to fly the bird only with Quest's slightly smaller diameter engines...

Mark II

08-15-2009, 12:07 AM

Ah, thank you for the explanation. Needless to say, I resolved never to do that again. :-)

However, wrapping the sand paper around the handle of a no.1 handle Xacto knife makes it not-too-painful to sand the inside of a BT-5 engine tube. A larger engine tube would have been a much bigger pain--although if it had been a BT-20 I could have just resolved to fly the bird only with Quest's slightly smaller diameter engines...
Coating the insides of motor tube walls with thin CA is actually not a bad way to toughen them up and make them more durable. It turns them into something that is kind of like phenolic tubing. You just have to remember to sand them out afterward and you may need to do a second application and sanding after the first in order to get the paper thoroughly impregnated. But do not lean over the tube and breathe while you are applying the CA :eek: (lean back or hold it out away from you and make sure that you have plenty of ventilation and De-Bonder handy) and don't insert anything into the tube until all of the CA is fully cured! In the meantime, enjoy the pretty clouds that come off of the tube as the volatile water-thin CA evaporates. :D

MarkII

j.a.duke

08-15-2009, 10:27 AM

The assumption here is that the Rocket is always launched and recovered successfully, launch after launch. Never a crash or mishap.

With that being said: How long does a Model Rocket last (to be flown again)?

Well, if you don't let your children handle it, a pretty long time.

Each time one of my kids wants to "hold" a rocket until we're ready to launch means that we'll be placing that one in the repair pile when we get home. They're old enough to be careful, but something always happens....

But, back on topic, I've got 30 year old rockets that can still fly; I've replaced the shock cord and they seem to do quite well. That said, most of them are in "emeritus" status now-still able to fly, but I want to keep them intact for my nostalgia and for display, since they look a lot better finished than most of what I've built since becoming a BAR. Must have had a lot more time as a kid to do all this stuff :) .

As an aside, isn't Vern Estes still flying an early (original?) Big Bertha at NARAM and other special events? If so, that's got to be at least 40 years old, if not older.

Cheers,
Jon