Friday, January 3, 2020

Test Shots

Happy New Year!

If you've listened to the latest episode of The Rocketry Show podcast, you know that I recently bought myself a nice, entry-level digital SLR camera. I'm hoping to get better photos of my family, of my rockets for this blog, and better video for my YouTube channel.

Here are just a few of my first shots - taken without totally knowing what I'm doing yet - that I took with my Canon Rebel SL3 - or 250D.

(It's known as an SL3 in the US and Canada and a 250D elsewhere. I bought it from a discount distributer in Brooklyn from eBay, and I got a non-US branded 250D. It's the same camera.)

No real sense to these. I'm mostly just playing around with the focus and depth of field.

With a wide aperture, I can focus on a specific point, separating it from foreground and background objects. See here how I focus on the N00b Tube in the first photo, then on the Astron Sprint XL decal in the second. This will be good for showing specific details in blog posts.

Shooting through the fleet to pick out just the Dr. Zooch Saturn V.

Even in pretty low light, I think this closeup of R2D2 looks pretty good. This action figure is only about 2 1/2 inches tall.

Some of Mrs. N00b's giraffes, mentioned on the show. Again, I'm just trying this thing out here. I don't even know how to do any post-production stuff on photos yet, so I have to say, I'm pretty pleased how well a quick shot like this comes out.

This fidget spinner was moving quite fast, but even in relatively low light, I was able to nearly freeze it with a fast shutter speed. If this were a rocket, and outdoors in brighter light, I'd probably get a nice still shot - if I managed to actually catch it with the shutter!

An artsy-fartsy photo of the Rocket Room (it's finally organized and clean!!)

Andy the Penguin hopes you had a good holiday season. Now, get to building rockets!

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Friday, December 13, 2019

Estes G40-7 Is Discontinued

I knew this was coming. I knew it for a couple years. I expected it to come sooner, and when it didn't, I started to think maybe it wasn't happening.

But it has happened. The Estes G40-7 composite motor is gone.

This 29mm single use motor was manufactured by AeroTech, like all Estes composites. The G40 was the highest impulse Estes motor you could purchase. I really like the motor, especially for flying Estes Pro Series kits, as well as for things like my North Coast Rocketry SA-14 Archer.

It was a simple motor to use, and performed really well.

I'm pretty sure I heard that the motor had been discontinued a couple years ago, when we spoke with Estes' designer John Boren on The Rocketry Show podcast. They had some left in stock - a couple thousand, perhaps - but when those were sold, the G40 would be gone forever.

Then Estes changed hands, and the G40 did not sell out as fast as I had assumed it would. Because of that, I was secretly hoping that they had decided to continue producing it. I bought a small stockpile of them, just in case, but I hoped I'd be able to pick some up for a long time to come.

Well, my stockpile is the last I'll be able to fly of this motor. I checked AC Supply today, and they finally had the motor listed as Discontinued. You can no longer find them on the Estes website. It's really, finally gone.

There are plenty of other mid power composites to choose from, of course. And I still have a stash of G40's, so I won't be out for a while.

But I really like this motor, and I'm sad to see it go. It makes me wish I'd grabbed even more when I could. I don't think it was a terribly popular motor, but I love it. In fact, I've probably flown more G40-7's than any motor other than the C6-5!

It's simple, has a relatively long burn, and you can fly it without a waiver or high power certification.

G40 thrust/time curve, from

It was also cheap, if you got it from the right source. AC Supply sold them at 40% off, which put them at just above $16 per motor. There was a HAZMAT fee to pay, but if you bought a large bundle of them, the shipping was free, so the HAZMAT became negligible. $35 is a lot of HAZMAT to pay for one motor. But if you buy a lot of, say twenty (I did that once), you're only paying an additional $1.75 per motor.

Time will tell if Estes gets back into composite motors. I won't hold my breath on this - I don't think Estes motors were as popular among APCP flyers as AeroTech or Cesaroni. But Estes definitely has plans on releasing new motors, and who knows what the future may bring?

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Wednesday, December 11, 2019

Estes Nike-X - Part 2

This is a little tool I made. I made it to help me create perhaps a dozen or so little rockets and build them all as close to exactly the same as I could. It's just a used motor casing with a 1/4 inch length of BT-20 body tube glued around the base of it. A second 1/4 inch length of body tube is not glued on, but can slide on and off the motor casing.

See, I have a project I've been thinking about for this blog, which may never come to fruition, but it's been in the back of my mind for a long time. And for it, I need multiple rockets built as close to precisely the same as I can get. This tool is to help me build multiple copies of Flechette, a skinny, high-flying two-stage rocket I designed.

I flew - and lost - the prototype a couple seasons ago, but the proof of concept flight went well, and man, did it go high!

The booster stage of Flechette has a motor overhang - that is, the motor hangs out the back - by 1/4 inch, while the sustainer (upper stage) has an overhang of 1/2 inch. Since I wanted all my Flechette rockets to be the same, the tool I made is for pushing an engine block or thrust ring up into the tube a precise distance. With the basic pushing tool, I can get all my boosters to have the engine block set into the tube so all booster motors hang out 1/4 inch. If I slide the loose ring onto the pushing tool, now I can install a thrust ring that will leave 1/2 inch overhang. It'll be exactly the same every time.

I like precision, if I can manage it. I was never good at precision before I started building rockets. Making stuff was not something I was good at. So, while I don't have the knowledge of a maker who's been using tools or crafting things for a couple decades, I do my best to make things more precise if I can think of a way to do it.

Which is why I did this:

The Estes Nike-X instructions say to place the engine block inside the motor tube with a 3/8 inch overhang. My little pusher tool wouldn't work for that.

Look, friends, I know. I know... This is fussy and silly, and a totally unnecessary step. I'm not suggesting that you need to do this.

But wanted to, because I like precision, so I did it.

I measured the pusher tube supplied with the kit, marked 3/8 inch from the bottom, and wrapped it with tape. No need to put my thumbnail on the pencil mark - I could push the engine block precisely into place, and now that I have this in my tool box, I can use it for another build which uses the same measurement.

Look, don't make fun of me. Just use your thumbnail and you'll be fine.

Or, if you like this idea, use it.

Actually, this isn't a terrible idea if you're building with kids for the first time. More than one of my rocket camp kids pushed their tubes all the way into their rockets, leaving no overhang, because they forgot to keep their thumbnail on the mark. Your thumb is supposed to be what stops you from pushing the engine block too far into the rocket. Kids - or sloppy adult builders - might forget this and shove it all the way inside. You really need the motor to hang out the back a little bit, or you won't get it back out of the rocket after its first flight. If you're teaching a rocket class to kids, making a few of these with used casings might come in handy.


If you look at the motor mount for the Nike-X I'm building, you'll notice that the engine hook has no thumb tab.

I first learned that people sometimes cut this tab off from Chris Michielssen's Model Rocket Building blog. I didn't understand why you'd do that when I first started building rockets. I used to like the tab. It made it easy to pull the hook out of the way and insert an engine into the rocket.

But the more rockets I built, the more I realized that the tab can be in the way more often than not.

If you buy motor hooks from other vendors, for building your own, you usually won't have a thumb tab. And some companies' kits don't come with them - Semroc, for example.

You can cut the tab off, which involves using some wire cutters and a lot of force to score the bend in the hook where the tab starts, then wiggling it back and forth until it breaks off. I use needle nose pliers for this.

You can then either sand or file the rough end you've cut, or use that as the top end of the hook. The tabless end now becomes the bottom and holds the motor in.

I used to file the rough cut, but I found it tedious. I followed Chris' advice and simply turned the hook around on this one, and it works great.

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Saturday, November 30, 2019

The Thrifty Rocketeer

This month, I succeeded in re-starting this blog through my #NaRoBloMo effort. I didn't seem to make an impact on social media. I think I'm the only person who used that joking hashtag.

But one reader did join me. Kirk G, a longtime listener and supporter of The Rocketry Show podcast, as well as reader of this blog, has started his own rocketry blog, The Thrifty Rocketeer.

It's always good to see more rocketry blogs out there. We always love seeing other people's builds and techniques.

CLICK HERE to check out Kirk's new model rocketry blog!

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Thursday, November 28, 2019

Estes Nike-X - Part 1

Once I got the Semroc Bandit all glued together, the next kit I semi-randomly pulled from the build pile was the Estes Nike-X, another nice BT-55 kit.

I like BT-55 rockets. It might be my favorite low power tube size. I'm not sure why. A BT-55 tube (1.325 inches in diameter) feels nice and sturdy, and it's versatile. Some BT-55 kits look like little rockets, and others are surprisingly big.

All I know is that a lot of Estes kits which grab my eye happen to be made of BT-55 tubes.

The Nike-X is loosely based on the Nike Zeus missile.

Several missiles in the Nike family, with the Nike Zeus closest to the camera

Here are the parts to the Nike-X kit.

You can see from the decal sheet that the black parts of the rocket are all decals. That means painting will be easy - the whole rocket will be done in gloss white. Sometimes, it's nice to have a simple paint job.

Just below the sheet of balsa fins, you see the motor tube. This is longer than a lot of motor tubes you get for 18mm A/B/C motors. A beginner might wonder why the long engine tube?

That's because this rocket has what's called a stuffer tube. The motor mount is longer, with the forward centering ring farther up in the body.

With the centering ring closing off the body tube much closer to the nose cone, the volume of the inside of the rocket is smaller. This is to aid in ejecting the nose cone.

With a large volume rocket, sometimes a small ejection charge can have trouble pressurizing the entire inside of the body tube enough to successfully eject the parachute. By using a stuffer tube, you make the inside of the rocket effectively smaller, meaning there's less space for the ejection charge to have to pressurize.

Truly, though, for a rocket of this size, I don't think that's really necessary. I have plenty of BT-55 rockets the same length as the Nike-X, and some larger rockets, none of which use a stuffer tube, and I've never had an issue with recovery.

The Big Bertha is an interesting example.

It uses a BT-60 body tube, and so is larger in diameter than the Nike-X. Some Big Bertha kits come with a stuffer tube, and some come with a standard 2.75 inch long engine tube. Mine has a short tube - no stuffer. And I've never had a problem with the nose cone ejecting.

But using a stuffer tube here isn't going to hurt anything, so I guess it's better safe than sorry.

The fin sheet was warped slightly.

Warped fins can drive you crazy, but they can be fixed. CLICK HERE for my post on different methods of fixing warped fins.

When I examined the fins more closely, it looked like the balsa sheet had warped in the bag. While the sheet had a bend in it on one side, the fins looked like they might actually still be flat.

In the above photo, you can see the underside of the sheet. The sheet curves away but the fins stick out.

Once I cut the fins loose and stacked them on the table, they looked like they were fine.

I wouldn't need to break out the glass cleaner this time around.

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Friday, November 22, 2019

Brodak Is Back

A few months ago, I learned from Bill Cooke's Rocketeer's Corner blog that my favorite sanding sealer, by Brodak, was out of stock.

I learned about Brodak from Bill's blog, and I love using it to seal the wood grain on balsa fins.

Everyone has a favorite method of hiding wood grain on balsa fins to make them nice and smooth for painting. The top three favorites include sanding sealer (which goes back to the early days), Elmer's Carpenter's Wood Filler, and papering fins. I did a detailed study here on The Rocket N00b blog a while back, focusing on how much weight each method added. CLICK HERE to read that post.

While I use each of these methods occasionally, by far my favorite is sanding sealer. Not only does it add the least weight, I find it the least frustrating.

This is just a personal taste thing. There is no "best" method.

A popular brand of sanding sealer in the past was Aerogloss, but it went out of production a few years ago. There are other brands of sanding sealer out there, but Brodak is my favorite to work with of the ones I've tried.

Brodak was out of stock for a while, and I worried it was simply not coming back, so I emailed the company to ask when it might be returning.

Patti from Brodak replied:

Hi Daniel,

We are waiting on the metal cans to come in. This should be back in stock within the next 2 weeks.

Sorry for the delay.

This was in early September. It must have taken longer than anticipated for the cans to be resupplied, because I kept checking the website, and long past a two-week period, the sealer was still out of stock.

But it's finally back, so I ordered more.

Sanding sealer, particularly this one, is more expensive than other methods of hiding wood grain. It puts out fumes, and should therefore only be used in a well-ventilated area. And, unless you can find a local supplier of it, you'll have to order directly from and pay shipping. But I like the stuff, so I consider it worth the price tag.

Also, I like the quality of it. Every time I opened a new jar of Aerogloss, if I didn't use the whole thing up in a few days to a week's time, it would crystalize and become useless.

I've used an opened can of Brodak on multiple projects for nearly a year, and only at the end did it start to thicken up. A dash of lacquer thinner made it useable one last time.

Brodak comes in 4 ounce or 16 ounce cans. The 16 ounce is a far better deal.

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Monday, November 18, 2019

Sounding Rockets; Cutting-Edge Science, 15 Minutes at a Time

At 2pm today, NASA live-streamed an hourlong program on sounding rockets - research rockets which carry scientific payloads on short, suborbital trajectories.

Here is the video:

If the player does not work for you on this blog, CLICK HERE to go directly to the video on YouTube.

I like sounding rockets, because of all launch vehicles, they're the ones which most closely resemble what we do in hobby rocketry. They're usually fin stabilized, they usually use solid propellants, and rather than go into orbit, they go up and come back down.

Sounding rockets look much like sport models, and doing a scale model of one is often much simpler than doing an accurate scale model of, say, a Saturn V or Mercury Redstone or Falcon Heavy, or Atlas Something.

In fact, one of the earliest model rocket kits, the Aerobee Hi, was a scale model of a sounding rocket which looked so much like a sport model, that when you see a scale model of it, you'd be forgiven for thinking it was just another model rocket.

The Aerobee Hi sounding rocket

I've been wanting to see more on YouTube about sounding rockets from NASA, but until today, I didn't find a lot that was terribly informative. Now that I have time to sit down and enjoy it, I'm hopeful it will have some interesting stuff in it.


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