Lakeroadster's "High School Confidential"

[lakeroadster]

I LOVE the staged GDS design! Have you considered using a cluster of D12s in the first stage? If you really want to “Cheap and Dirty” it, what about gluing 2 or 3 motors to the central CHAD booster motor?

I second the desire for Estes to make the C5-0. Up there with the D12 with the best max lift : weight ratio of all the Estes engines (9.6:1).

C11-0 is only listed as 170g max lift. That is going to be close even with 4x 18mm engines. Maybe D12-0 in lowest and C11-0 next.

D12-0 + C11-0 + C6-0 + B6-0 + B6-6

Actually fits into the Highschool thing if you do something like this (how many people had E's instead of F's in their schools)...

E12-0 + D12-0 + C6-0 + B6-0 + A3-6

I agree that would make for an even more awesome launch visual.

The issue is that would push the apogee up so high I'd likely never find the upper stages..... I'm trying to keep the rocket under 800 feet to maximize my chance of recovery of all the components.

Where we launch there is tall grass at the outskirt of the field. A lost rocket, or lost rocket stages & motors, is an opportunity for a fire. Safety 1st!

 

[BDB]

I love everything about this project. One more comment and then I’ll sit back and live vicariously through this thread…You can cant booster motors to minimize the altitude and maximize the awesome.

 

[lakeroadster]

I love everything about this project. One more comment and then I’ll sit back and live vicariously through this thread…You can cant booster motors to minimize the altitude and maximize the awesome.
View attachment 530289

I like it! Are those all booster motors, did you plug any of them? (Note: Keep the comments coming, "sitting back" is frowned upon. )

I've done a triple 24mm canted tractor motor, and I've done dual 24 mm canted sustainer.... but not a canted cluster booster.

 

[BABAR]

Love the cruise missile mode!

 

[BABAR]

…You can cant booster motors.

I am glad you can cant them.

It would be sad if you can’t cant them.

 

[BDB]

I am glad you can cant them.

It would be sad if you can’t cant them.

I was struggling with that sentence when I wrote it. I’m glad someone else noticed the irony too!

 

[lakeroadster]

Started the drawing set.

Since I'm using 24mm to 18mm adapters... I can run a couple really small screws through the BT-50H into the plastic adapter case just to ensure everything is good-n-tight (That's an old world, German term).

 

[jqavins]

Sorry I'm late. And, sorry to say, I think staged GDS is a terrible idea and should be verboten.

Surely you've noticed that, when direct staging, there is, more often than not, a tiny pause. WOOOSH-pause-WOOOSH. GDS is effective only when there's thrust. During that pause, the rocket will tip, just a little bit. During each pause, as the remaining rocket get's lighter and lighter, and all at one end, the moment of inertia will drop a lot and the amount of tip will increase. Either it tips so far that the sustainer crashes, or little enough that you can kiss the sustainer good bye.

 

[lakeroadster]

Sorry I'm late. And, sorry to say, I think staged GDS is a terrible idea and should be verboten.

Surely you've noticed that, when direct staging, there is, more often than not, a tiny pause. WOOOSH-pause-WOOOSH. GDS is effective only when there's thrust. During that pause, the rocket will tip, just a little bit. During each pause, as the remaining rocket get's lighter and lighter, and all at one end, the moment of inertia will drop a lot and the amount of tip will increase. Either it tips so far that the sustainer crashes, or little enough that you can kiss the sustainer good bye.

Ah yes Grasshopper, but you have forgotten the tiny fins that make it .

I've already proven that design with THUNK!... it's stable throughout the entire coasting phase of it's D12-3 motor.

But now that you've made me re-think this design, or should I say re-thunk this design... eliminating the fins on the 1st stage might be a good idea. The first stage may suffer from drag separation.

Thanks for the reply Joe.

 

[jqavins]

Ah yes Grasshopper, but you have forgotten the tiny fins that make it .

I've already proven that design with THUNK!... it's stable throughout the entire coasting phase of it's D12-3 motor.

I see. Yes, that does make sense. It still makes me nervous, but I guess that's my own problem.

 

[lakeroadster]

It still makes me nervous, but I guess that's my own problem.

Why? In any event, doing things that make you a bit nervous is kind of the spice of life.

 

[jqavins]

Why? 1) For the reason I originally stated, and 2) because I irrationally can't let go of that reason even though your response makes perfect sense and is backed up by empirical experience. Thus, "that's my own problem".

 

[lakeroadster]

Why? 1) For the reason I originally stated, and 2) because I irrationally can't let go of that reason even though your response makes perfect sense and is backed up by empirical experience. Thus, "that's my own problem".

I guess maybe if you were there and saw Thunk! fly (which was awesome if I must say so myself) you'd have a point of reference.

 

[jqavins]

That's likely. But not certain. I'm just highly risk averse, so if I can see a reason to think there's more than the usual risk that goes with every model rocket launch, it will make me a bit nervous. For example, with all motors installed this is a lot heavier than Thunk!, so it will not only be going up more slowly, it will also be spinning more slowly. But the gyro stabilization effect should also increase with mass (well, moment of inertia) so maybe heavier and slower cancel out. But maybe not.

It's an experiment, and sometimes experiments go wrong. My inner Safety Officer says "Woah, slow down!" and my (somewhat less) inner rocket scientist says "We learn from failures more than we do from successes, and we have safety practices that make the risk of injury or property damage very, very small" and my (also not so) inner rocket enthusiast says "PUSH THE BUTTON!"

So my three inner selves argue among themselves, and it averages out to a little nervous.

 

[lakeroadster]

That's likely. But not certain. I'm just highly risk averse, so if I can see a reason to think there's more than the usual risk that goes with every model rocket launch, it will make me a bit nervous. For example, with all motors installed this is a lot heavier than Thunk!, so it will not only be going up more slowly, it will also be spinning more slowly. But the gyro stabilization effect should also increase with mass (well, moment of inertia) so maybe heavier and slower cancel out. But maybe not.

It's an experiment, and sometimes experiments go wrong. My inner Safety Officer says "Woah, slow down!" and my (somewhat less) inner rocket scientist says "We learn from failures more than we do from successes, and we have safety practices that make the risk of injury or property damage very, very small" and my (also not so) inner rocket enthusiast says "PUSH THE BUTTON!"

So my three inner selves argue among themselves, and it averages out to a little nervous.

 

[lakeroadster]

I just stumbled upon this post by @AeroTech. I've never seen this technique used, it's ingenious. You (almost) get TTW performance, on a minimal diameter airframe.

I gotta try this on the fin can for this rockets 1st stage.

 

[jqavins]

I love it. just know I'd manage to eff that up if I can't come up with a jig, guide, or some sort of aid. But with my friend and housemate having a new 3D printer, and already turning out rocket parts, I'm sure we'll come up with something.

 

[lakeroadster]

Some subtle changes:

• Roll patterns on the body & nosecone
• Tweaked the fin shapes and size to increase stability > 1.0 caliber during stage 1 phase for all 3 simulated motor combinations.

Event Data:

• 2nd stage ignition at 96 feet - 9 rev/ sec roll rate
• 3rd stage ignition at 278 feet - 29 rev/sec roll rate
• 4th stage ignition at 367 feet - 32 rev/sec roll rate
• 4th stage burnout at 447 feet - 32 rev/sec roll rate
• Apogee at 599 feet - 9 rev/ sec roll rate

​

 

[lakeroadster]

I measured my stock of body tubes and decided to look at making the sustainer body tube longer. It allows me to decrease the ballast a bit. So I end up with a lighter rocket, that has a bit higher apogee.

Which version do you think looks better? Original or Stretched

Original



_____________________________________________________________________________________________________________

Stretched

 

[jqavins]

Mostly, to me it's six of one, half dozen of the other. Not that it doesn't make a difference, but neither is really better than the other. To me.

 

[BDB]

I think I prefer stretched.

 

[Dotini]

I measured my stock of body tubes and decided to look at making the sustainer body tube longer. It allows me to decrease the ballast a bit. So I end up with a lighter rocket, that has a bit higher apogee.

Which version do you think looks better? Original or Stretched

Original

View attachment 533411

_____________________________________________________________________________________________________________

Stretched

View attachment 533416

Either way, it's a mind-boggling design. But form follows function, so the if the longer one works better, it looks better.

 

[emmah]

HS Confidential is a great rocket name.

 

[lakeroadster]

HS Confidential is a great rocket name.

And a tip of the hat to you for knowing the reference.​

 

[jqavins]

Is it something other than a reference to LA Confidential?

 

[lakeroadster]

@jqavins

 

[bjphoenix]

The issue is that would push the apogee up so high I'd likely never find the upper stages..... I'm trying to keep the rocket under 800 feet to maximize my chance of recovery of all the components.

I might have missed it but why are you staging? You don't need staging for 800'.

I remember long ago Estes had 2-stage and 3-stage kits in the catalogs, but back then the biggest motors available were 18mm B although they had C motors for boosters. There was the 3-story Farside advertised to go 2,500 feet, with weight of 2.0 ounce. The recommended engines for the first state were strangely enough 1/4A and 1/2A, and the core burning B. With heaviest recommended motors the total weight would be just under 4 ounces, and they didn't recommend a C motor in the first stage. I thought the 1/4A and 1/2A were odd recommendations but each of these would have a short duration of high thrust but no length of lower thrust after that so they are counting on the short high thrust then getting to the next stage of short high thrust to keep it going.

 

[lakeroadster]

I might have missed it but why are you staging? You don't need staging for 800'.

With all due respect... did you even read the first post?

 

[jqavins]

I might have missed it but why are you staging? You don't need staging for 800'.

The staging is the point of the whole thing. Then, to ensure all the pieces are found, the altitude must be kept down despite the staging. Of course staging isn't needed to reach 800 ft.; he could fly the sustainer alone with an 18 mm composite D motor and reach 1000 ft. or better if that were what he wanted.

Lake, I see above the D-C-B-A engine sequence, and that the apogee is below 800 ft. as you're wrote you're trying for. So good. But, if the true goal is "keep it low", with 800 ft. as a maximum allowed (and that's truly an "if") one could go something like D-A-A-½A. That sim could be titled "You'll find it EASY."

 

[bjphoenix]

With all due respect... did you even read the first post?

I did, but then when I got to the 800' part that wasn't consistent with staging and I forgot all about the first post.

I've been through this type of conflicting goals a couple of times recently-
1. I have a lot of C6-3 motors to use, so I was looking for a rocket light enough to fly with a C6 but with enough drag to work with 3 sec. delay time. There is such a thing, and there have been several Estes kits with recommendations for C6-3. The Fat Boy kit with 18mm mount was one. I ended up scratch building a rocket, that I haven't had a chance to fly yet.
2. I found a pack of D12-7 in my old stuff. I was wondering what size rocket launches with this motor but would not get so much altitude that recovery could be compromised. I found that the HiFlier XL was the kit so I bought one and built it.

The problem of launching a 3-stage or 4-stage and keep it under 800' seems like you would need something reasonably light but with a lot of drag, maybe BT80. I've never gotten into staging because I usually was able to get all the altitude I wanted with a single stage.