I've never flown a D motor.

[Worsaer]

You have not paid your dues until you have flown, and cato'd a D motor. I have cato'd more than I can count.

I knew I had some old video kicking around somewhere... VHS from 1996.

I had two of these CATO on the same day.

[video]https://youtu.be/h3SbXL7XXQ8[/video]

 

[pyrobob]

I knew I had some old video kicking around somewhere... VHS from 1996.

I had two of these CATO on the same day.

[video]https://youtu.be/h3SbXL7XXQ8[/video]

Yeah, our first ever cato was a D12 way back in the late 80's or early 90's. That video is about what it looked like .

 

[noffie79]

Built an Estes Patriot with a 24mm hole. About two months ago flew my first D & E motors. So now, A, B, C, D, E, F, G and H

 

[K'Tesh]

Over a 3 day period back in September I flew the alphabet from A to I (not in that order though)

 

[noffie79]

Over a 3 day period back in September I flew the alphabet from A to I (not in that order though)

I haven't decided which "I" will be my first. But when it happens, it'll be in my Estes Leviathan. Going to get that bird as close to Mach 1 as possible. It may shred, but I've got parts to build two more. If you haven't seen it, MaxThrust has an awesome video of his going Mach on an I224

[video=youtube_share;JCPzjzWlG_E]https://youtu.be/JCPzjzWlG_E[/video]

 

[DAllen]

Um...no.

Just because RS or OR says mach 1 doesn't mean it happened. 3100' and it hit M1? I doubt it even went transonic.

I've used that tubing in another build and was not impressed with it's strength so I am admittedly surprised it held up to an I.

Edit: Just ran a sim with a Leviathan on OR with an I224 and it says 3400' and Mach .88. If I adjust the weight so it hits 3100' it'll be slower obviously. If you you really want to go mach with a rocket of this size I suggest going minimum diameter or putting a 38mm hole in it with a J. You'll have to glass it up good and get a tracker.

 

[noffie79]

In the video, his RS said he'd be short of Mach. I think 80mph shy. So he wasn't expecting to go that fast. But in another video with the ground view, you can clearly hear a boom shortly after it launched. I don't know if the weather was absolutely in his favor that day, or if it was simply a fluke, but either way, it's pretty impressive for a PSII kit

 

[DAllen]

That Leviathan probably hit 500 mph. It was likely the motor spitting part of the liner and not a sonic boom. You have to go past the sound barrier and have a large aircraft to create a "boom." Rockets make more of a crack if it can be heard at all.

 

[noffie79]

His Jolly Logic Altimeter 2 did say it went I think 674 mph. I'd have to watch the other video again to confirm. It's a ways into the video, 20 minutes or so, but still a great video with a hell of a lawn dart

[video=youtube_share;qVI3EWuuNC0]https://youtu.be/qVI3EWuuNC0[/video]

 

[Reinhard]

But in another video with the ground view, you can clearly hear a boom shortly after it launched.

A rockets sonic boom is a rather unpleasant sound to hear, because it always means the rocket is getting closer. Most of the time, it also means that you've been unprepared for this and it is already to late to react.

The sound in the video wasn't a sonic boom, because the sonic boom is never projected backwards.

Reinhard

 

[DAllen]

A rockets sonic boom is a rather unpleasant sound to hear, because it always means the rocket is getting closer. Most of the time, it also means that you've been unprepared for this and it is already to late to react.

What? If a rocket is going faster than the speed of sound then you aren't going to hear it coming if it is heading straight toward you.

The sound in the video wasn't a sonic boom, because the sonic boom is never projected backwards.

Reinhard

No. A sonic boom is always behind the supersonic object because sound can only travel at mach 1.

https://en.wikipedia.org/wiki/File:Dopplereffectsourcemovingrightatmach1.4.gif

Turn that animation 90 degrees and you can see how a rocket going supersonic would project it's "boom." If you are far enough away and the conditions are right it is entirely possible to hear a rocket break the sound barrier.

 

[grouch]

I've gone well past Mach several times and I never heard a boom. In fact, I have never heard a boom at any launch that wasn't part of a separation event but then again I tend not to stand near the Porta Potty when I fly.

 

[Reinhard]

What? If a rocket is going faster than the speed of sound then you aren't going to hear it coming if it is heading straight toward you.

You're right, the rocket "was" usually approaching when you hear it, but it is possible that the rocket "is" approaching. Rockets can decelerate and change course, therefore it is not necessarily given that the rocket is past you, when you hear the sound. Possible examples are various reentry scenarios.

No. A sonic boom is always behind the supersonic object because sound can only travel at mach 1.

https://en.wikipedia.org/wiki/File:Dopplereffectsourcemovingrightatmach1.4.gif

Turn that animation 90 degrees and you can see how a rocket going supersonic would project it's "boom." If you are far enough away and the conditions are right it is entirely possible to hear a rocket break the sound barrier.

The boom trails the rocket, but it is still projected forward (and outward). The animation demonstrates this nicely. Somebody who remains at x=0, regardless of y, is not able to hear the boom.


Reinhard

 

[Bat-mite]

How interesting that a thread about D motors could evolve into one about the science of sonic booms.

 

[ThirstyBarbarian]

How interesting that a thread about D motors could evolve into one about the science of sonic booms.

Yes, I'm getting this back on track.

I remember my first D like it was just yester-D.

I'd say if you haven't flown a D by this point, then you should just resolve to NEVER fly a D. Life should have some mysteries, and this can be yours. Then when you are gone, your headstone can read "He never flew a D."

 

[boatgeek]

Getting back to the original thread, an 18mm D21 is a perfect solution to the Estes Wizard you are tired of gluing fins back on to. It really makes the problem go away. That was the only D I've flown.

I've never flown A or less, and have only gotten up to I. FWIW, the I was a I140 DMS (thanks pyrobob!) in a minimum diameter and minimum length piece of silliness built from a saran wrap tube. OR said M1.15, but I didn't have enough confidence in recovering it that I was willing to risk an altimeter. Plus I didn't have space. I had to pack the mylar chute something fierce just to get the nose cone on.

 

[Bat-mite]

Yes, I'm getting this back on track.

I remember my first D like it was just yester-D.

I'd say if you haven't flown a D by this point, then you should just resolve to NEVER fly a D. Life should have some mysteries, and this can be yours. Then when you are gone, your headstone can read "He never flew a D."

I like it!

 

[rstaff3]

I think I saw a photo of you flying a 'D' on the cover of the National Inquirer.

 

[KenECoyote]

Okay folks, here's the best reason for flying a D engine...you just have to with this one. :grin:

This is the Estes 36 D Squared and it was originally named "Double D's"...check out the very interesting story about it here (Post #5): https://rocketshoppe.com/forums/showthread.php?t=11946