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The H410 is a great L1 motor! The 123 is another. Both will leave a lasting impression.
No truer words... The H410 is a beast...on cardboard.. even better... building techniques will be tested and flaws will be found 😂😂😂😂😂😂😚😚

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Base drag. I wondered how those curled-up foam pool noodles flew! I'm not an aero student - or maybe I'm a student of any subject - but I love learning things here.

From cambridgerocket, a fabulous PDF: The aerodynamic forces are complex phenomena and there are no simple analytical solutions for the coefficients. In the incompressible flow regime the forces can be divided into pressure force and viscous force. Pressure force arises through the stagnation of fluid on the rocket forebody, fins, and any other protrusions, and also through a suction force created by a low pressure region at the base of the rocket where boundary layer separation occurs. Viscous force is due to skin friction between the rocket and the air. ... The base drag on the rocket is the drag due to the low pressure region at the base of the rocket that is caused by boundary layer separation. This drag is estimated using equation (42):

BaseDrag1.png
db = max body diameter
dd = base diameter
Cd(fb) = Cd of rocket forebody


From UiO in Norway:

BaseDrag4.png



BaseDrag2.png

UiO also had this super shock wave photo!

ShockWave.jpg

From the Flight Dynamics Laboratory, Wright-Patterson AFB, July 1984:

BaseDrag5.png

The last formula is based primarily on aircraft, but I thought it was interesting to compare the two equations. I couldn't find a definition of Sref, but S in this document is surface area. Clearly a noodle rocket's Sbase must approach Sref, explaining its high base drag and stability.

Andrew: one day you will be applying for a job. Maybe it's time to learn that HR departments these days are very good a combing the net for posts and breaking through anonymity using outsourced big-data correlations. What company wants to hire someone who's posted pix of themselves snorting coke? Every year the search algos get better, so it's only going to get more transparent. You're leaving embarrassing breadcrumbs, unless you're planning a career in bowling ball design.

So imagine yourself applying at Lockheed or Boeing someday, then after a good interview HR calls and asks "Are you Andrew_ASC?" Whatcha gonna say about your posts? That you were too lazy or arrogant to search the net? That you thought you knew everything in your early 20's? For goodness sake, in less than an hour I learned how noodle rockets have stability and why boat tails are so good (which I use for benchrest target shooting)... and it's all about base drag, not pixie dust.

In fluid mechanics for plate drag forces in direction of velocity flow over body, the Aref term represents cross sectional area not surface area perpendicular to velocity flow. The Sref term likely represents the entire body surface area parallel to velocity flow compared to Sbase or tailcone surface area. I never got a chance to learn about base drag as a mechanical engineer student because it is outside of my field and you guys already accuse me of false behaviors. Wow. Don't apply a compressible Mach situation above Mach 0.3 to incompressible flow fluid mechanics formulas. That's why there's an additional course compressible gas dynamics to deal with normal shocks, oblique shocks, Rayleigh, Prandel, heat addition, and reflections of shocks. No HR staff previously ever referenced a single post. I pass my drug tests. Some engineering students did not pass and were promptly terminated. I was employed by VW last summer under a contract. Yet this forum remains hostile. Perhaps I was rude at times. I only studied skin drag on a golf ball versus other spheres with a wind tunnel in fluids lab and plate drag mainly for a senior design project nosecone/airframe/airfoils I've designed with CFD assistance and also for theoretical engineering fluid mechanics/gas dynamics/heat transfer with applied fluid mech problems. Also designed launchpad. The difference between an engineer and a non engineer is the engineer even the dumbest one that graduates is licensed by the state and can take a FE and PE exam to increase pay or ultimately to sign off on designs. The engineer attempts to understand when formulas can be applied in theory to practical problems. The engineer is a human being who can be terminated in a career field for negligence or ethics violations in design that hurts people. Engineering is split into many different disciplines. Don't ask a Aero\IE guy to do journal bearing life cycles on vibration filled impact loaded shafts.

I'm not going to make fun of the guy that designs experimental aircraft without a degree, one company of one dude familar with formula SAE car assembly produced a sparless CF aircraft, but the company went bankrupt when other aerospace companies supposedly allegedly had borrowed the design idea with internal partnership arguments and actually made it with a certified reliable aircraft engine rather than an untested automobile engine. This aircraft looked like the Lancair Evo oddly. The buyers trusted the company with licensed engineeers. Lancair had a rather accident filled learning curve and additional FAA oversight by using air racing wings on light GA aircraft which lead to numerous stall/spin crashes with abnormal spin behavior but the proprietary airfoil was faster than certified mooney. Eventually Lancair had factory training courses to assist pilots and accident rates dropped. The Lancair IV-P turboprop had wonky moments of Inertia causing stability issues. A diploma is a foot in a door to learn. Despite all the problems Lancair had they are a successful light aircraft experimental manufacturer. The sole inventor lost his life savings by not having a diploma or ability to sign off on documents with engineering credibility. There is a difference between an inventor and a engineer. The engineer can lose a career. The days of Wilbur Wright Brothers flying an aircraft from a bicycle shop and turning a profit are over by insurance and legal liabilities by an over-regulated society. Inventors will still invent but they will struggle to profit fighting commercial companies.
 
Well I thank TRF for helping me understand base drag. I hope this guy has a good L-1 cert.
 
He will, if I have anything to do with it. See you at Snow Ranch Randy. Bring your paperwork.

F'in eh. I'm gonna maiden this Smoke for my L1 with you at my side. I hope swatkat will be there too.


Andrew: go away. Go away mad if you wish, just go away.
 
Base drag. Not many people account for it. You think a spool, pyramid or saucer has a stable CG/CP relationship. I think my crayon and "running with scissors" are in the .4 cal range. But simming it with base drag cone adds almost one full cal. And they fly great.

Its kinda funny how a simple "what should I use for L1" draws comments that are obviously misplaced and well about what the OP was asking. And I have read the same comments about a failed rocket launch in 3 different posts...View attachment 341208View attachment 341209

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Only three?! Lucky you! I've got to where I barely read his posts. Hate to be like that but I've never seen so much off topic ramblings.

ill take "what is a rabbit hole" for 500 alex...

Alice in Wonderland. She falls into the rabbit hole and enters the world of shrooms, Hookah smoking caterpillars, the Cheshire cat and one wild tea party. Never heard of it? LOL

The Matrix. Morpheus tells Neo "You take the red pill—you stay in Wonderland, and I show you how deep the rabbit hole goes"

I'm only joking with you of course.

My short stubby Wastelander (Cowabunga) is a regular flier with a stability of less than .5. For my Tembo I had to add 8 oz of lead to get it to .4 CAL, but that is with 54mm Js. If I can get the short stubbies close to 1 CAL using the rear drag cone I'm happy. .9 usually works well enough, drop the cone and the stability goes way down.

Good luck on your cert. We had a guy get his L1 with a Madcow Little John this past Saturday. Of course, I was working and missed it. But scale missiles are too short, stubby, horridly unstable, poorly designed, with not enough interior packing room and not enough packing room for the motor (new one on me) to be able to fly properly. But somehow he made it work.

David mentioned colored skies.

What planet has green skies and blue grass? Hint: It is in the Aldente Nebula in the Andromeda Galaxy?

Again, good luck.
 
Alice in Wonderland. She falls into the rabbit hole and enters the world of shrooms, Hookah smoking caterpillars, the Cheshire cat and one wild tea party.

Lay your head on the Surrealistic Pillow... let Grace fill your soul...
One pill makes you larger​
And one pill makes you small​
But the ones that mother gives you​
Don't do anything at all​
Go ask Alice...
When she's ten feet tall​


And if you go chasing rabbits​
And you know you're bound to fall​
Tell 'em a hookah smoking caterpillar​
Has given you the call​
Call Alice...
When she was just small


When the men who are on the chessboard​
Get up and tell you where to go​
And you've just had some kind of mushroom​
And your mind is moving slow​
Go ask Alice...
I think she'll know​


When logic and proportion have fallen sloppy dead​
And the white knight is talking backward​
And the red queen's "Off with her head"​
Remember what the door mouse said:

Feed your head...
Feed your head...
Feed your head.......​

The Matrix. Morpheus tells Neo "You take the red pill—you stay in Wonderland, and I show you how deep the rabbit hole goes"

"Why didn't I take the blue pill???"

Rob Zombie throbs: follow the white rabbit...

WhiteRabbit.jpg


I know a lot about you. My name is Trinity.

Trinity.jpg


I know what you've been doing.
I know why you hardly sleep.
Why you live alone, and why night after night you sit alone at your computer.

It's the question that drives us.
The answer is out there.
It's looking for you.

Neo.jpg
 
The Troll Room. This is a small room with passages to the east and south and a forbidding hole leading west. Bloodstains and deep scratches (perhaps made by an axe) mar the walls. A nasty-looking troll, brandishing a bloody axe, blocks all passages out of the room.

I still vote for the H410 to be the second flight...
 
I still vote for the H410 to be the second flight...

Even though the sim predicts 59Gs? I'll weigh the NC, multiply by 60, and think about stacking books on the BT. That seems like a huge motor.
 
Not sure if it's still the case but wasn't there a period where you couldn't fly the Vmax motors without electronic back up due to the delay snuffing issue? I never had a single issue with any of my Vmax motors (a shed load) but I seem to remember either NAR or Tripoli weighing in on it.

The H410 is a special load for sure. I chose to cert with it because I was trying to overthink my rocket. In the LOC Onyx, the stability margin is small so I figured the faster I get it up to speed and burn off the propellant, the better off I'd be. It jumped off the rail like it was shot from a cannon and I didn't see it after that. I walked the field where I thought it would be for a good hour or so and was completely dejected when I couldn't find it. Turns out some jamoke picked it up for me and brought it back to the LCO's table. Had I known I could have saved some miles on my legs and stomach pitting from worry. What a special day, it was one of the last NERRF launches in NY and the weather was perfect. Awesome sauce for sure.
 
In the LOC Onyx

H410 in the Onyx? It looks like a Smoke. LOC says its cardboard is thick, but the Estes tube couldn't be called thick. Maybe if I CA in the 2mm CF rods from MM to NC...

BTW with the new weights the sim says 56G.

You folks wouldn't suggest this if it was irrational, would you? When she was 14, my daughter said "Dad, the word gullible is written on the ceiling over you." And I looked up.
 
Last I heard VMax motors are still required to be flown with an electronic recovery. Are you looking at flying the Nike Smoke on an H410?

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56G is a lot. LOC cardboard is noticeably thicker than Estes, and the shortness of the Onyx helps it out too.

Its possible to do a smoke on an H410. I wouldn’t recommend it.
 
Its possible to do a smoke on an H410. I wouldn’t recommend it.

Thank you, David. I would rather do a slow burning motor that I get to watch. Funny thing - thrustcurve.org did not ID the CTI H123SK as suitable when I ran the Smoke yesterday. I wish I could ask it why.
 
Last I heard VMax motors are still required to be flown with an electronic recovery. Are you looking at flying the Nike Smoke on an H410?

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That’s correct. Electronics are still required by both NAR and TRA when flying Vmax motors due to a high rate of delay grains snuffing out.
 
Electronics are still required by both NAR and TRA when flying Vmax motors due to a high rate of delay grains snuffing out.

Steve, where does a person look to find critical information such as this?
 
Doesn't Thrustcurve have a "motors that failed" list as well? And it says why it failed? Haven't used it in while. I usually have some fail because speed off rail is too low for Thrustcurve but not for me. Don't think that is the case here though. It may be that you have specified too short a MMT.

Steve, where does a person look to find critical information such as this?

https://www.tripoli.org/CTI-VMAX-motor-flight-restrictions
 
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Thanks, Mike.

I don't want to sound intransigent, but if not for TRF I wouldn't have known to even look for this info. I wish there was a central clearinghouse, such as Thrustcurve. I looked there before posting, but found no note WRT H410.

I am new in HPR, so please forgive me if I've missed the obvious. I just want someplace I can enter a motor and see if there are any "NOTAMs" issued for it, such as the link you provided.
 
Thank you, David. I would rather do a slow burning motor that I get to watch. Funny thing - thrustcurve.org did not ID the CTI H123SK as suitable when I ran the Smoke yesterday. I wish I could ask it why.

Sometimes Thrustcurve doesnae have da powah. :) You'd be fine with the H123 on the Pro-Series Smoke if built reasonably well. (Given your background I don't have any doubts). The H410 would be another story. I personally wouldn't do it, but it would be entertaining either way, once the candle was lit. :) A great simple series of motors is the 29/180 reloads. The H128 is the good ol' cert standby and BAR (the guy with the trailer at the launches) offers a SWEET deal for the reload case, closures and the H128 reload. Also for that same case is the H165R and H238T. I like those motors a lot for their cost/total impulse ratios and the ability to send the Estes kits to 2000-2800 feet depending on the kit. Smoke would likely end up at 2600-2800 feet. Perfect for keeping it in sight for the duration of the flight. H115DM would be a similar range of heights on a single use motor, but the L! cert deal from BAR is hard to beat. You basically get the H128W for free.
 
H410 in the Onyx? It looks like a Smoke. LOC says its cardboard is thick, but the Estes tube couldn't be called thick. Maybe if I CA in the 2mm CF rods from MM to NC...

BTW with the new weights the sim says 56G.

You folks wouldn't suggest this if it was irrational, would you? When she was 14, my daughter said "Dad, the word gullible is written on the ceiling over you." And I looked up.

some people are into the low and slow, some are in the middle.. then there are a few on the fringe who everyone makes fun of until that button is pressed down......

This will give you "some" idea of what I was referring to with the H410... The first time I launched one, I knew it was a one way trip.. The rocket went buh bye... like.. still not found to this day. I have a few ideas for my next 410 project.. aside from the case.. its pretty much a single use rocket, and the chances of getting the case back.. slim to none.. and im ok with that.... I dream of the day of a single use H410...

This will give you a hint of why I recommend the 410 for your second flight. Not to this extreme..but you'll understand... :lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol:

https://youtu.be/EqNSwOw1myw

p.s. Please feel free to make fun of me..
 
BAR's L1 cert deal does sound nice. I'm committed to the H115DM at this point, primarily for the spark shower and single-use DMS simplicity, but it also has a nice thrust curve; 12.1 Gs and apogee almost 2000'. Funny thing, the H128 pushes 15.4Gs but only 1650' apogee. I don't want to sim my life away, but it's extremely interesting to see how thrust curves relate to performance.

The CTI starter 29mm start set with 3- and 6-grain cases, etc., is also high on my list. Having Mike come to the launches makes CTI affordable in small quantities.
 
Steve, where does a person look to find critical information such as this?

Tripoli has the Tripoli Motor Testing announcement page.
https://www.tripoli.org/TMTAnnouncements

I don’t know where the announcement is on the NAR site. I looked but could not find it.

Motorcato.org has several announcements about motors that have surprised people, but the CTI Vmax announcement isn’t there. It’s obvious that we need a better system. I would love to have a single database that lists all the motors, their test results, and a way to collect mess reports against them, and any announcements. I would have no problem if that were ThrustCurve or something similar. ThrustCurve already exists, but of course it doesn’t belong to either NAR or TRA. That could even be a benefit.
 
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BAR's L1 cert deal does sound nice. I'm committed to the H115DM at this point, primarily for the spark shower and single-use DMS simplicity, but it also has a nice thrust curve; 12.1 Gs and apogee almost 2000'. Funny thing, the H128 pushes 15.4Gs but only 1650' apogee. I don't want to sim my life away, but it's extremely interesting to see how thrust curves relate to performance.

The CTI starter 29mm start set with 3- and 6-grain cases, etc., is also high on my list. Having Mike come to the launches makes CTI affordable in small quantities.

Hmmm, those are values significantly lower than I would expect. I launched a Leviathan (3" tube/four fin/23 Oz w/o motor) on an H165R and it was 1860'. I would expect the Nike to go much higher. Partizon on a H128W (2.6"/19 Oz w/o motor) was 2580...
 
Tripoli has the Tripoli Motor Testing announcement page.
https://www.tripoli.org/TMTAnnouncements

I don’t know where the announcement is on the NAR site. I looked but could not find it.

Motorcato.org has several announcements about motors that have surprised people, but the CTI Vmax announcement isn’t there. It’s obvious that we need a better system. I would love to have a single database that lists all the motors, their test results, and a way to collect mess reports against them, and any announcements. I would have no problem if that were ThrustCurve or something similar. ThrustCurve already exists, but of course it doesn’t belong to either NAR or TRA. That could even be a benefit.

I personally have found that the on site motor vendor (animal motor works) is by far the most knowledgeable and informative resource there could possibly be. With that said, I only use CTI so for me its a simple as a phone call. The onsite vendor had motors that were labeled "checked, passed" for a delay recall/verification and offered to check my older inventory.

Tom
 
Hmmm, those are values significantly lower than I would expect. I launched a Leviathan (3" tube/four fin/23 Oz w/o motor) on an H165R and it was 1860'.

Thanks for looking over my shoulder. That seemed odd to me also, so I simmed the H165R and got an apogee of 1764' at 19G's. Not too far off from yours. Maybe the Smoke's wider NC and transition add enough drag to cause the difference?
 
ThrustCurve already exists, but of course it doesn’t belong to either NAR or TRA. That could even be a benefit.

Agreed. No affiliation, nothing to hide. I wonder how we could chat with them? It would be quite valuable, especially in light of TRA's warning and NAR's lack of notice. If any certifying body has an issue - and some may be see issues others do not - the one entry would propagate to all ThrustCurve users.

Do you know anyone behind the site? If not, I'll just email webmaster and see what comes forth.
 
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