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lakeroadster said:
I ran a program called "stopwatch" on my laptop... and video taped it. Then looked at it frame by frame to come up with the actual time. :dontknow:

View attachment 565723
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This dead horse offends me, so I will beat it a little more.

What does that total time include? The time on YouTube's progress bar is about 12 seconds (there's only so accurately I can hit pause) from the D12's first hiss to the B6's ejection charge, so obviously it's not that whole. By the same "pause the video" method, the fuse burn event seems to be one second.

Right from the start I found one thing in your numbers odd, and didn't bother to post about it until @BABAR's post, because it is too small to matter.
1677511886876.png
The second row of the burn rate calculations says that 100 frames times 0.033 s/frame is 3.34 s, rather than 3.3 or 3.33. But 100 frames at truly 30 fps is 3.33 s. A tenth of a percent different and unimportant. Today I remembered that in the NTSC spec (old analog TV) the rate is not exactly 30 fps, but ever so slightly off; I looked it up and learned it's 30/1.001, i.e. a tenth of a percent. So I checked and found that it's the same for HD. That would make 100 frames 3.3376 s, rounded off to 3.34. So your numbers are correct on that point. But that leads to 24 frames being 0.8008 s, or rounding to 0.801 s, not 0.802. So, as you say: :dontknow: . That changes my other answers to 48.701 in/s or 4.058 ft/s.

But all this is fiddling around in the fourth or fifth significant digit, and I feel comfortably certain that the fuse's burn rate must vary by more than that not only from batch to batch but from foot to foot off the same roll.

It's all BABAR's fault; I wouldn't have weighed in if he hadn't first. ;)
 
jqavins said:
This dead horse offends me, so I will beat it a little more.

What does that total time include? The time on YouTube's progress bar is about 12 seconds (there's only so accurately I can hit pause) from the D12's first hiss to the B6's ejection charge, so obviously it's not that whole. By the same "pause the video" method, the fuse burn event seems to be one second.

Right from the start I found one thing in your numbers odd, and didn't bother to post about it until @BABAR's post, because it is too small to matter.
View attachment 565858
The second row of the burn rate calculations says that 100 frames times 0.033 s/frame is 3.34 s, rather than 3.3 or 3.33. But 100 frames at truly 30 fps is 3.33 s. A tenth of a percent different and unimportant. Today I remembered that in the NTSC spec (old analog TV) the rate is not exactly 30 fps, but ever so slightly off; I looked it up and learned it's 30/1.001, i.e. a tenth of a percent. So I checked and found that it's the same for HD. That would make 100 frames 3.3376 s, rounded off to 3.34. So your numbers are correct on that point. But that leads to 24 frames being 0.8008 s, or rounding to 0.801 s, not 0.802. So, as you say: :dontknow: . That changes my other answers to 48.701 in/s or 4.058 ft/s.

But all this is fiddling around in the fourth or fifth significant digit, and I feel comfortably certain that the fuse's burn rate must vary by more than that not only from batch to batch but from foot to foot off the same roll.

It's all BABAR's fault; I wouldn't have weighed in if he hadn't first. ;)
Click to expand...

Yeah Joe, but @BABAR had a substantive valid point about an error I made...

And you sir, with all due respect, are "picking the fly **** out of the Carpenters Wood Filler"... to coin a phrase.
 
Finishing: Prepping For Paint My least favorite part of the sport

Applying the CWF

001.JPG 002.JPG​

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After sanding

01.JPG​

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Ready for primer... so to Paint Jail the Mighty Saturn V does go

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Just a single, high power, long burn, 21st century. modern gimbaled motor will solve all yer problems. But no! Have to fly it like it's 1969 with lots of black powder motors all fused and staged up like the real McCoy! That is the ONLY WAY to capture the boyhood sense of wonder last felt during the Summer of Love. We do these things because they are hard! Old school rules! 1960's Christmas at Gimbals rules!
 
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lakeroadster said:
I can, it's that I choose not to. For more data, refer to "Gimbal" .... And I'm not talking about the department store from the movie "Elf".
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It was supposed to be a pun, hence the absence of the ‘ in cant.

I think it is a good plan, somebody remarked on the “severity” of the angle, but given big heavy rocket and itty bitty fins that are only on first stage, they only have a short time and altitude to act.
 
BABAR said:
I think it is a good plan, somebody remarked on the “severity” of the angle, but given big heavy rocket and itty bitty fins that are only on first stage, they only have a short time and altitude to act.
Click to expand...

Agreed. :headspinning: The fins are only on the 1st stage, which separates from the rocket after 1.6 seconds. :headspinning:
 
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BABAR said:
It was supposed to be a pun, hence the absence of the ‘ in cant.

I think it is a good plan, somebody remarked on the “severity” of the angle, but given big heavy rocket and itty bitty fins that are only on first stage, they only have a short time and altitude to act.
Click to expand...
Just plug in the hopesim version where the tiny canted fins do not impart spin while on the pad. Then have them spin up the rocket at speed just before second stage ignition, imparting lovely, stabilizing spin! No pop out fins or ugly, rack rocket conduit braces needed!

All the big and little kids have to do is believe...in spin stabilized spirit! Together we will power the rocket to stability! Send those positive waives man! Oddball rules!

Remember, this is coming from the workshop of Pappa Elf...creator of the Kringle 3000. A powerful strap on engine powering Santa's sleigh with flawless stability! Just sing your favorite Christmas Carole and have a cup of good cheer! :)
 
Golly jeepers the peanut gallery is on fire...no good canted fins blah blah blah. Just wait for Block 2, when all the motors are canted too! All spinning around a central launch lug on the pad. Flash pan ignited, spin stabilized, perfectly timed staging all wrapped up in amazing good looks and scale accuracy! :)
 
Daddyisabar said:
Just plug in the hopesim version where the tiny canted fins do not impart spin while on the pad.
Click to expand...

Okay, I have heard of Thrust Curve, OpenRocket, RockSim, and MindSim,
HopeSim is a new one for me.

Somehow I suspect at sanctioned launches Darth RSO banishes HopeSim rockets to the far pad.

As I am sure @lakeroadster is aware, this puppy will need a stiff rod firmly attached to the ground. That’s a lot of rocket playing “Ring Around the Launch Rod” during those first three feet or so. Given the small fins however, I expect it will be fine.
 
BABAR said:
Okay, I have heard of Thrust Curve, OpenRocket, RockSim, and MindSim,
HopeSim is a new one for me.

Somehow I suspect at sanctioned launches Darth RSO banishes HopeSim rockets to the far pad.

As I am sure @lakeroadster is aware, this puppy will need a stiff rod firmly attached to the ground. That’s a lot of rocket playing “Ring Around the Launch Rod” during those first three feet or so. Given the small fins however, I expect it will be fine.
Click to expand...
When your mindsim crashes in the central processing unit, all that is left is the core hopesim. That's usually good enough until an upgraded version on a CD arrives in the mail. Must be a Columbia House record club member though...;)

Search your feelings. Use the Force!...

Yeah. OK, whatever. Just do it at the far far away pad!
 
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Golly, no love for the canted fins and spin stabilization from the scum and villainy crowd at the cantina! How ironic, they all want the straight and narrow path! Who do they think they are? Some kind of Jedi? No Jedi mind tricks. Only money works on my mind. And I bet my money on the boy!

They tricked! me! The Jedi foresaw the future! :)
 
BABAR said:
Okay, I have heard of Thrust Curve, OpenRocket, RockSim, and MindSim,
HopeSim is a new one for me.

Somehow I suspect at sanctioned launches Darth RSO banishes HopeSim rockets to the far pad.
Click to expand...
The Hopesim is a story the Jedi don't like to tell...
 
BABAR said:
Okay, I have heard of Thrust Curve, OpenRocket, RockSim, and MindSim,
HopeSim is a new one for me.

Somehow I suspect at sanctioned launches Darth RSO banishes HopeSim rockets to the far pad.

As I am sure @lakeroadster is aware, this puppy will need a stiff rod firmly attached to the ground. That’s a lot of rocket playing “Ring Around the Launch Rod” during those first three feet or so. Given the small fins however, I expect it will be fine.
Click to expand...

5/16" galvanized steel launch rod, 72" long, 66" usable rod length, fastened to the launch horse via a steel satellite dish antennae bracket that is hell-for-stout.

But since the launch characteristics of the rocket, due to the canted fins, seems to be a bone of contention... I will clamp (2) pieces of 6 foot long pvc pipe to my launch horse such that the fins of the rocket would rub against them and thus prevent any spinning from occurring until the rocket clears the launch rod.

Thoughts? @BABAR @Daddyisabar @boatgeek @jqavins


Launch Horse Modifications For Saturn V.jpg006.JPG​
 
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lakeroadster said:
5/16" galvanized steel launch rod, 72" long, 66" usable rod length, fastened to the launch horse via a steel satellite dish antennae bracket that is hell-for-stout.

But since the launch characteristics of the rocket, due to the canted fins, seems to be a bone of contention... I will clamp (2) pieces of 6 foot long pvc pipe to my launch horse such that the fins of the rocket would rub against them and thus prevent any spinning from occurring until the rocket clears the launch rod.

Thoughts?


​
Click to expand...
you had me at 5/16”, 72 inches………..

I fear that my attitude in comments is not coming across well, I think your building skills and techniques are amazing (your wood stuff rivals a lot of 3D printing!) and what I mean as suggestions are coming across as criticisms (which when I read them I understand, so I’ll take the hit on that.)

sometimes I justify my comments to myself as, “I am sure HE knows this, but others that might emulate this might not think about……”. due to your creativity, your engineering skills, and your meticulous documentation and drawings, you are becoming one of the “legendary” forum members (somebody had to take @hornet driver ‘s place, since I haven’t seen a build from him in a long time, he also did some amazing stuff). Anyway, you have quite a following and I sometimes see stuff that may deserve some commentary for those who read these. Probably just self-aggrandizement on my part.

i think you will be fine with simply the 5/16” rod, I have never heard of using that thick a rod (although I probably would have had I read your detailed posts more closely, as I suspect you have ALREADY mentioned it several times.) Sounds perfect for this one, since you can’t use a rail.

your internal launch lug that goes straight through a transition is also likely effective rock solid (I would have doubts about an external lug with those canted fins.). Hard to know how much if any the rocket will spin much before it leaves the rod.

in this case, SINCE YOU ASKED for my opinion on the PVC pipe mod (rather than just something gratuitous on my part), I think it is a Brilliant solution, but a bad one.

you are thinking of a launch tower, sort of, but with a launch tower while there is always some drag, there is little force pushing the rocket laterally (or rotationally) against the guides. Here IF there is a significant rotation force (and I am not sure there will be much, as I don’t know how much velocity the rocket will develop in the first 6 feet), but IF there is much force, it’s rubbing against your pipes (although you only need one, it is only going to rotate in ONE direction.) My concern is that you are adding complexity and potentially drag (forcibly “scraping” the fin against the pipe the whole length), bad enough on a single stage, but for a multi-stage, one of the highest priorities is getting it smoothly off the rod at the highest velocity possible. You are better off leaving as is.

if it ain’t broke, don’t fix it. I do hope you have a dedicate relatively high speed camera at the launch fixed on the pad (sort of shades of @Ronz Rocketz ) as it will be more interesting to watch that “rod phase” than typical rockets.

lots of people (not me, but lots) have done scratch Saturn Vs, fewer have staged it, but your use of spin and base drag stabilization of the upper stages is, I think, unique, and I wish you the best.
 
BABAR said:
you had me at 5/16”, 72 inches………..

I fear that my attitude in comments is not coming across well, I think your building skills and techniques are amazing (your wood stuff rivals a lot of 3D printing!) and what I mean as suggestions are coming across as criticisms (which when I read them I understand, so I’ll take the hit on that.)

sometimes I justify my comments to myself as, “I am sure HE knows this, but others that might emulate this might not think about……”. due to your creativity, your engineering skills, and your meticulous documentation and drawings, you are becoming one of the “legendary” forum members (somebody had to take @hornet driver ‘s place, since I haven’t seen a build from him in a long time, he also did some amazing stuff). Anyway, you have quite a following and I sometimes see stuff that may deserve some commentary for those who read these. Probably just self-aggrandizement on my part.

i think you will be fine with simply the 5/16” rod, I have never heard of using that thick a rod (although I probably would have had I read your detailed posts more closely, as I suspect you have ALREADY mentioned it several times.) Sounds perfect for this one, since you can’t use a rail.

your internal launch lug that goes straight through a transition is also likely effective rock solid (I would have doubts about an external lug with those canted fins.). Hard to know how much if any the rocket will spin much before it leaves the rod.

in this case, SINCE YOU ASKED for my opinion on the PVC pipe mod (rather than just something gratuitous on my part), I think it is a Brilliant solution, but a bad one.

you are thinking of a launch tower, sort of, but with a launch tower while there is always some drag, there is little force pushing the rocket laterally (or rotationally) against the guides. Here IF there is a significant rotation force (and I am not sure there will be much, as I don’t know how much velocity the rocket will develop in the first 6 feet), but IF there is much force, it’s rubbing against your pipes (although you only need one, it is only going to rotate in ONE direction.) My concern is that you are adding complexity and potentially drag (forcibly “scraping” the fin against the pipe the whole length), bad enough on a single stage, but for a multi-stage, one of the highest priorities is getting it smoothly off the rod at the highest velocity possible. You are better off leaving as is.

if it ain’t broke, don’t fix it. I do hope you have a dedicate relatively high speed camera at the launch fixed on the pad (sort of shades of @Ronz Rocketz ) as it will be more interesting to watch that “rod phase” than typical rockets.

lots of people (not me, but lots) have done scratch Saturn Vs, fewer have staged it, but your use of spin and base drag stabilization of the upper stages is, I think, unique, and I wish you the best.
Click to expand...

The only rocket I've launched on a 1/8" launch rod is my X-Wing Alpha. My rockets are just to heavy for such a flimsy rod. And a launch rail wouldn't be ideal for my Saturn V either, due to possible binding of the rail buttons, due to torsion from the canted fins.

And in regard to your comments not coming off right.... No worries.

Rod whip at launch due to canted fins is a topic @Daddyisabar has been poking me with a stick about for months. I value his input, but don't always follow his advice. Then you picked up a stick and started poking and I value your input also. So Grumpy Bear started typing out a response... and thinking of the value of eliminating the possible issue.

My mind sim tells me it won't be an issue, simply because of the amount of weight that needs to be rotated in such a short length and the lack of airspeed pre-launch rod clearance. But my sense of reason tells me the last thing I want is a more horizontal than vertical flight, or worse yet a Steve Austin ground impact and the ensuing rocket shredding ground tumbling event. I've had that experience in the 70's with my Christmas Tube Rocket... link here: "High School Confidential".

It would be relatively easy to make a launch tower out of pvc, or even wooden closet rods, for this rocket and that would address the rotation issue.

Thoughts?


Satrun V Launch Tower.jpg Poke The Bear.jpg​
 
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Recognizing that the plural of anecdote is not data...

I wouldn't worry much about wrapping the rocket around the axle, either with a rod or with a rail. I've launched LPR and MPR with more-canted fins off of both rails and rods and had no issues. I don't think that the rocket is moving fast enough off the rail/rod for it to really matter. For reference, LPR was a light 29mm on a B6 an 1/8" rod and MPR was a heavier ~2" on an F36 and a rail. Both flew straight and true.

I agree with @BABAR that drag on a fin is worse than a little rotation around the rod. I would posit that drag on 4 fins is only marginally better (symmetrical, but more drag).

FWIW, YMMV, FLAs all the way down.
 
Your openness to input commendable, but there is the proverb that

A camel is a horse designed by a committee.

Not that I have anything against camels.


Get this painted, take some great glamour shots , and light this candle!
 
Those fins at best will generate so little force at low speed as to induce only a slight roll at best just as it leaves the rod. That actually excited a scale points post I saw on Facebook. Love that NASA roll program call out after clearing the tower. I don't think that poster realized the fins were for stabilization.

Those tiny fins won't spin stabilize anything in my mindsim. So rod whip and tourqe issues effecting ignition and flight angle from such fins are the least of the problems faced by this lovely sports scale machine!

The Facebook peanut gallery posts were calling for clear fins on the upper stages. They just don't get it! :)
 
lakeroadster said:
The only rocket I've launched on a 1/8" launch rod is my X-Wing Alpha. My rockets are just to heavy for such a flimsy rod. And a launch rail wouldn't be ideal for my Saturn V either, due to possible binding of the rail buttons, due to torsion from the canted fins.

And in regard to your comments not coming off right.... No worries.

Rod whip at launch due to canted fins is a topic @Daddyisabar has been poking me with a stick about for months. I value his input, but don't always follow his advice. Then you picked up a stick and started poking and I value your input also. So Grumpy Bear started typing out a response... and thinking of the value of eliminating the possible issue.

My mind sim tells me it won't be an issue, simply because of the amount of weight that needs to be rotated in such a short length and the lack of airspeed pre-launch rod clearance. But my sense of reason tells me the last thing I want is a more horizontal than vertical flight, or worse yet a Steve Austin ground impact and the ensuing rocket shredding ground tumbling event. I've had that experience in the 70's with my Christmas Tube Rocket... link here: "High School Confidential".

It would be relatively easy to make a launch tower out of pvc, or even wooden closet rods, for this rocket and that would address the rotation issue.

Thoughts?


Click to expand...
Just prodding the Cocaine Bear to think about all the issues. Must go over each tiny detail again and again, till your puzzler is sore on such a complex rocket. Rocket Science is HARD!

And it's a tough crowd here on TRF. But underneath the outrageous slings and arrows are hearts of pure Gold... just a little stained from numerous crashes in the past.
 

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