What did you do rocket wise today?

[Grog6]

Today I used the excellent info in the professors book, to make a set of polyurethane bushings, for my Cougar. I ended up with some httb from a manufacturer that's just too hard for rocket motors; you load it with aluminum and perchlorate, and the grains all crack. Bot it seems to make great bushings, lol.

 

[WrRider]

Saturday my Dad,kids and I drove out to the desert for a family launch. We had somewhere around 12 Rockets six of them were made in flights. I had my first dual deployment rocket (even though both flights deploed both chutes at apogee)Katana Jr . My dad scratch built a Nike Hercules and a launch rail for it that one didn't get destroyed but didn't fly right some issues with his CG. My son had boosted Bertha and a Superbird both launched great the Superbird was a 25-30-year-old kit we found in my dad's garage. Unfortunately it was a little bit windy so I couldn't stand up all the models to get a good picture but it was a great day. Forgot my dad also had a Mercury Redstone with the old motor that catoed he was able to fix it on site

 

[lakeroadster]

Mars Lander body (it's a woody) and CAD Model... 29mm

​

 

[frogglicker]

I made the trek out to Ft. Lupton, CO for CRASH with the family this morning. My son launched his Imperial Max 2x, the wife launched her Barbie Pink Max, and I got to send my Mega Red Max.

The Mega tried to take the rail with it to space, which shaved about 800 ft off the apogee. This made for a nail-biter deployment. I think the JLCR saved it from a zipper, as I watched it coming in, I saw the ejection of the nose cone fully extend, then the chute inflated moments before landing. No damage to the rocket.

 

[Antares JS]

Clearcoated Der Squared Max, installed recovery system. It will be ready to fly as soon as the glue on the knots dries.

 

[bjphoenix]

Wikipedia has only a small selection of materials in the Examples section of its article on Young's modulus. It has only one steel alloy, A36, with a modulus of 200 GPa, and only one alloy of aluminum, not specified, at 68 GPa. Of course, various alloys will have values that are closer together or further apart, but I rather any but a very expensive, exotic aluminum alloy (if that) could compete with steel.

Steel alloys are all pretty close together in stiffness, I don't know about alloys for aluminum. Steel alloys that you might encounter in your daily life can vary in strength by around 10 but their stiffnesses will all be within a small percent variation.

 

[Antares JS]

Clearcoated BOSS, installed motor mount and shock cord.

The nose still smells like paint, so I'm waiting longer to clearcoat it. Once it's clearcoated all I need to do is tie the parachute and shock cord to it.

 

[teepot]

If memory serves one of the old Estes mid-power pads had an aluminum launch rod. Is there an aluminum alloy that's stiff enough for a 1/8" rod? Less rod whip than steel. I have my doubts.

I got a 6' 1/4" aluminum rod at Home Depot and it's arrow straight. They have steel too. Their rods start at 1/16th and go up from there.
Friday I received the Eurmax No Matter 10x10 pop up I ordered. It had been on my wish list about a year. IIRC when I first added to my list it was $250. Then $200. When I looked the last time it was $145.98 and I hit the buy now button. It's still listed at that price.

 

[lr64]

Wikipedia has only a small selection of materials in the Examples section of its article on Young's modulus. It has only one steel alloy, A36, with a modulus of 200 GPa, and only one alloy of aluminum, not specified, at 68 GPa. Of course, various alloys will have values that are closer together or further apart, but I rather any but a very expensive, exotic aluminum alloy (if that) could compete with steel.

EDIT: On the other hand, the stiffness of a member (stop tittering) is proportional to the fourth power of it's dimension of interest, so for a given material, a 3/16 inch rod is just over 5 times stiffer that a 1/8 inch rod. There are some metals, e.g. molybdenum, that have greater Young's moduli than steel, but just go with 3/16 steel.

Depending on the application, MANY aluminum alloys can "compete" with steel. Especially if weight is limited, but space is not, and you're worried about buckling or bending. OTOH, if the load is tensile, the part is necessarily stubby enough not to collapse, or the temperature is high, a good grade of steel will be hard to beat. Of course, if you are constrained to 1/8", steel is your best bet.

As per your edit, which I saw just now, an aluminum rod that's 3/16" in diameter will be significantly stiffer than the 1/8" steel rod.

BTW, one can straighten music wire. For 1/8", you'd need a piece that's somewhat longer than you need, a way to grab the ends securely, and a way to apply a bit over a ton and a half of tension*. ;-) It works great if you're straightening .030" music wire, anyway, and I can do that without mechanical assistance. It sure feels weird when the wire starts to yield.

-----------
*On further thought, applying that much force wouldn't be so hard. I own a come along that could do it. Like this: https://en.wikipedia.org/wiki/Come-along I'd need lots of extra music wire at the ends to wrap around things, though. Or appropriate fittings and a torch to braze them on with. It would be important to stay out of line with the wire, in case something broke.

 

[jqavins]

Depending on the application, MANY aluminum alloys can "compete" with steel. Especially if weight is limited, but space is not, and you're worried about buckling or bending. OTOH, if the load is tensile, the part is necessarily stubby enough not to collapse, or the temperature is high, a good grade of steel will be hard to beat. Of course, if you are constrained to 1/8", steel is your best bet.

As per your edit, which I saw just now, an aluminum rod that's 3/16" in diameter will be significantly stiffer than the 1/8" steel rod.

BTW, one can straighten music wire. For 1/8", you'd need a piece that's somewhat longer than you need, a way to grab the ends securely, and a way to apply a bit over a ton and a half of tension*. ;-) It works great if you're straightening .030" music wire, anyway, and I can do that without mechanical assistance. It sure feels weird when the wire starts to yield.

-----------
*On further thought, applying that much force wouldn't be so hard. I own a come along that could do it. Like this: https://en.wikipedia.org/wiki/Come-along I'd need lots of extra music wire at the ends to wrap around things, though. Or appropriate fittings and a torch to braze them on with. It would be important to stay out of line with the wire, in case something broke.

All true, and we're talking about the size constrained case where "if you are constrained to 1/8", steel is your best bet."

Using the particular alloys listed, steel's stiffness is almost three times aluminum's for a given diameter, and going up from 1/8 to 3/16 gives you just over a fivefold improvement, so yes, "an aluminum rod that's 3/16" in diameter will be significantly stiffer than the 1/8" steel rod" by about 71%; I'd still go with the 3/16 steel.

I've just talked myself into throwing out all my 1/8 launch lugs.

 

[lr64]

Are the 1/8 steel rods actually too floppy? There are, of course, several music wire sizes between 1/8 and 3/16, assuming one doesn't need the rod to be 5 times stiffer.

If one can afford iridium, of course, steel is no longer the best bet. And someday we'll get graphene. Then we can all use 0.084" rods.

 

[lakeroadster]

Are the 1/8 steel rods actually too floppy? There are, of course, several music wire sizes between 1/8 and 3/16, assuming one doesn't need the rod to be 5 times stiffer.

If one can afford iridium, of course, steel is no longer the best bet. And someday we'll get graphene. Then we can all use 0.084" rods.

Like the average rocketeer has 11 grand to throw down for a launch rod. Geeze ​

KISS: Keep It Simple Stupid​

​

​

 

[Antares JS]

Like the average rocketeer has 11 grand to throw down for a launch rod. Geeze ​

KISS: Keep It Simple Stupid​

​

​

View attachment 644026​

44 grand, once you get a long enough piece for a 3-foot/1-meter rod...

 

[lr64]

Like the average rocketeer has 11 grand to throw down for a launch rod. Geeze ​

KISS: Keep It Simple Stupid​

​

​

View attachment 644026​

Wouldn't have expected you to be a stoneface. Did you really thing I was serious?

 

[lakeroadster]

Wouldn't have expected you to be a stoneface. Did you really thing I was serious?

Yes, I take you at your word.​

 

[jqavins]

Are the 1/8 steel rods actually too floppy?

For the heavier LP and many MP rockets, yes. On a moderately windy day, maybe. The heavier kits come with 3/16 launch lugs, but rod whip has certainly been a problem for lighter rockets too, from time to time.

There are, of course, several music wire sizes between 1/8 and 3/16, assuming one doesn't need the rod to be 5 times stiffer.

But the launch lugs that come in kits or in bags of lugs don't come at sizes in between. Data and calculation may show that 0.150 is all you need, but your choices, based on the rocket parts that are available with minimal effort, are 0.125 (1/8) and 0.188 (3/16). So what's the downside of using 0.188? 32% greater weight. Some small difference in price. Who cares?

 

[NTP2]

44 grand, once you get a long enough piece for a 3-foot/1-meter rod...

Ahhh well just cancel that L3 project

 

[berlinetta]

This weekend I finished painting my LOC I-ROC and last night I applied the decals and installed the recovery system. Next, I'll start my 1/2 scale LOC Esoteric that I acquired. I'll also be ordering components to do a 4" I-ROC as well.

 

[RokitFlyr]

For the heavier LP and many MP rockets, yes. On a moderately windy day, maybe. The heavier kits come with 3/16 launch lugs, but rod whip has certainly been a problem for lighter rockets too, from time to time.


But the launch lugs that come in kits or in bags of lugs don't come at sizes in between. Data and calculation may show that 0.150 is all you need, but your choices, based on the rocket parts that are available with minimal effort, are 0.125 (1/8) and 0.188 (3/16). So what's the downside of using 0.188? 32% greater weight. Some small difference in price. Who cares?

Exactly! It's just a stinking launch rod for crying out loud. My 1st launch pad as a 12 year old in 1968 was a block of 2x6 with a straightened piece of coat hanger. Hammer forged by me. . Get over it and go ahead and fly a rocket!

 

[Lord Rory Gin]

On Saturday, I launched a number of rockets but the conditions were variable. A storm cloud passed through just as I was launching a Rocketarium Exocet. The winds conditions changed dramatically within a couple of minutes, previously coming out of the south at 14 kph to coming out of the NW at probably 2x that speed. The rocket launched on a D12-5 (ThrustCurve est. altitude of 500') but drifted about 900' into an irrigation ditch. I fished the rocket out and began to let it dry. On Sunday night when I returned home, it was still damp so I stuffed it with moisture absorbing packets. The engine is really damp and swollen so I have to wait until it is dried out before I can remove it.

Luckily the Exocet model has balsa ribs running the entire length of the rocket so the cardboard body tube has reinforcement otherwise it would have crumbled from the weight of the moisture. It has a small crumple just ahead of the baffle and a paint crack right at a tube joint but otherwise it is intact. This rocket will live to fly another day.

P.S. as I am reading the earlier posts, it struck me that I want to get a longer 3/16" rod. Mine is a 36" SS and I want to get a 48" version so its off to the hardware store today. Also to pick up some scrap 2"x4".

 

[ecargmij]

Fixed an issue seeing the astrocam led when inside an inverted pursuits lab mount.. modified the case to open up the led hole in the astrocam.like many have done.. I left mine mostly covered with the top cover .. I dilled a 7/64" hole from the screw retaining hole to the inside of the cover to line up with the led.. I bought some .10" plastic fiber optic off of Amazon (way more than I'll ever need 20').. but I slide that into the drilled hole.. the pics show it better.. it now has a top external indicator and from the front

 

[Tookanforever]

Wildman jr.. Looking forward to flying it at Airfest..

 

[Art Upton]

This weekend I finished painting my LOC I-ROC and last night I applied the decals and installed the recovery system. Next, I'll start my 1/2 scale LOC Esoteric that I acquired. I'll also be ordering components to do a 4" I-ROC as well.

That would be like a LOC EZ-I65 with the payload section left off

 

[Antares JS]

Repaired my Fat Boy XL with a new nose bulkhead. The eyebolt tore out of the old 3D-printed one. Thanks for the help, @DragonRocketry !

 

[lr64]

snip


But the launch lugs that come in kits or in bags of lugs don't come at sizes in between. Data and calculation may show that 0.150 is all you need, but your choices, based on the rocket parts that are available with minimal effort, are 0.125 (1/8) and 0.188 (3/16). So what's the downside of using 0.188? 32% greater weight. Some small difference in price. Who cares?

It's a little known fact that each launch lug was eventually intended as a kit for a smaller one, until someone got cheap. All you need is a heat gun, or maybe just a candle. Each steel rod that comes with a piece of paper is a kit to make a precisely sized, paper launch lug.

Exactly! It's just a stinking launch rod for crying out loud. My 1st launch pad as a 12 year old in 1968 was a block of 2x6 with a straightened piece of coat hanger. Hammer forged by me. . Get over it and go ahead and fly a rocket!

You're ruining all the fun. ;-p
----------
And yes, I did a little more work on the rocket glider today. Adjustable copper hinges for trimming the flight surfaces. Weight is creeping up.

 

[boatgeek]

Ordered parts for some students to do Jr L1 projects. A great use for the club's surplus nose cones! They'll run from 54mm to 4". I think there's a couple of kids looking to do kits as well, so we might have 5 Jr L1s this year.

 

[lr64]

Yes, I take you at your word.​

Strongly suggest that if what I write seems a bit ridiculous, you consider the possibility I'm pulling your leg. Especially if it sounds like I'm solving a problem by throwing disproportionate amounts of money at it.

---------------

BTW, when I win Powerball, I will purchase a large property, not too far out of town. It will have a rocket launching area, a dirigible hangar for indoor free flight and MMX rockets. There will be a pond for RC sailing guys, There will be a weather resistant, solar charged RC sailplane winch always available. Also a solar charged golf cart for retrieval purposes for anyone with limited mobility. The dirigible hangar will be oriented perpendicular to the prevailing winds for slope soaring. Maybe I'll build my subterranean mad scientist's lair underneath. In that case, fire and blast resistant areas with good ventilation and at least two exits will be provided for those who want to make propellant, as well as appropriate magazines for such material.

 

[Jeff Curtis]

Been falling down a certain rabbit hole for a few months now: a metal/silver paint that handles fingerprints, accepts colour, accepts decals and clear coat without mottling.

This may be it. Plastic scale modellers are raving about Tamiya’s AS-12 bare metal finish. I have watched a ridiculous number of YouTube videos about… yes… a can of spray paint.

Anyhoo… scored a few cans from what seems to be a meagre supply here in Oz. Just need some good weather and an appropriate rocket. I’m thinking a V2.

It’s $12.40 a can here, and Tamiya’s little cans only go so far.

View attachment 643376View attachment 643377

I order a couple of cans. I'll try it out on the 3" Dragon Rocketry Wolverine and the Squirrel Works Astrid.

 

[bjphoenix]

BTW, one can straighten music wire. For 1/8", you'd need a piece that's somewhat longer than you need, a way to grab the ends securely, and a way to apply a bit over a ton and a half of tension*. ;-) It works great if you're straightening .030" music wire, anyway, and I can do that without mechanical assistance. It sure feels weird when the wire starts to yield.

Holy tug of war Batman- you would have to pull at 1/8" diameter wire something like 3000# to get it to yield! That's a lot of pull, and it would be a challenge to grip the wire in such a way to pull it that much without causing it to fail at the grip.

Are the 1/8 steel rods actually too floppy?

YMMV, I haven't seen everything, and there can always be exceptions. 1/8" diameter steel rod x 36" length seems sufficient for rockets up to BT60 diameter with single 18mm motor mount. With single Estes 24mm mount generally 3/16" diameter steel rod x 36" length is enough. For rockets that might be slower we have 1/4" diameter rods x 6' long.
I've noticed that Estes stock launch lugs can be a bit tight even on freshly cleaned steel rods. On some of my recent builds I just rolled my own launch lugs and I made them a bit larger. I have a set of drill bits with a lot of sizes so for 3/16" rods I use a 15/64" diameter drill bit. I always use 2 short lugs spaced a little bit apart so a little extra slop in the launch lug doesn't affect anything.

My 1st launch pad as a 12 year old in 1968 was a block of 2x6 with a straightened piece of coat hanger. Hammer forged by me.

Same here but a few years before that. Slightly before 1968 I built an Estes Ranger (3-motor cluster). I rolled some paper launch lugs to use on it and bought a 1/4" diameter x 6' rod at the hardware store. I flew it 3 or 4 times with payloads and it flew great.

 

[lr64]

Holy tug of war Batman- you would have to pull at 1/8" diameter wire something like 3000# to get it to yield! That's a lot of pull, and it would be a challenge to grip the wire in such a way to pull it that much without causing it to fail at the grip.
snip

You may have noticed that I wasn't entirely serious. Nevertheless, this would work if you had enough extra wire, and a big enough pair of pliers, to wrap it around some strong bar, the way you would with smaller wire. And cheap steel might be straightened with only 1,000 lbs of force.