UncleVanya

After reading this and the comment that White Thunder has the highest total impulse of the Pro38 line I realized that there is a 5 grain J motor which seems to violate this. Overall the statement seems to hold true.

What design differences allow for the classic propellant to be the highest total impulse in the 5G case but not in any other in the 38mm line?

Dipstick

The 5G I540 was certified a couple years ago...might be why it doesn't have the same total impulse relationship as the others.

UncleVanya

Just to be clear - are you saying that the White Thunder of today might be more powerful than it was? If so the 5G WT load previously certified as an I540 might be pushing into J territory. As long as the delta is under (20?) a certain percentage the vendor doesn't have to recertify it but this puts the L1 / L2 status into question of this motor.

Interesting. I suspect it isn't that simple. I suspect it is based on some geometry issue - like the J285 is able to operate at a higher total efficiency and squeezes out a little more juice than the I540 at the same max operating pressure in that one case. But I don't have a definitive answer...

Anthony Cesaroni

Conspiracy?

Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

jsdemar

The aliens who landed in Gormley have not yet divulged that information to their keepers.

Anthony Cesaroni

Aliens? The strange lights in formation above the plant were just road flares tied to helium balloons. The ProX crop circles can probably be explained as well.


Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

Anthony Cesaroni

As previously mentioned, the 5G version was originally certified a few years ago. Vmax was a trade name given to one of our propellants for HPR use around the time for lofting bowling balls or something along those lines. We really didn’t retool much on the reload design given the limited numbers involved. In any event, the product was well received by consumers for sport rocketry use in its limited offering at the time.

There are a few reasons for the delta with the new versions. Because of the slower burn rate of the Classic propellant, the nozzle throat diameter is much smaller than for the White Thunder Propellants and the expansion ratio is limited by the molded nozzle for that particular reload/case module. For the larger White Thunder motors the expansion ratio becomes significantly smaller than for the Classic motors, simply because we ran out of room without resorting to a different aft closure and nozzle configuration. Also, the Classic propellant uses a graphite throat insert that keeps the average Pc up during the burn. The larger White Thunder motors have more severe erosion, and hence burn at lower average Pc. The classic load also has a tad more propellant load IIRC. Despite the moderately fast burn rate, 38 and 54mm Vmax motors retain fully adjustable delays and ejection charges and do not contain ferrocene or catocene additives.

We may tune up the 5G a bit in future certification sessions as time permits. It wasn’t a priority in the last go around as it was already in the books as configured.

Clear as mud?

Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

UncleVanya

Argh! I was hoping you'd pop in - but I was expecting a real substantive answer. Now all I can assume is that it involves some conservation of mass from another dimension. In other words... Alien technology stolen from area 51.

Anthony Cesaroni

Area 51 actually stole some of their technology from CTI Gormley. Well at least the road flares and helium balloons.

Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

UncleVanya

I heard that they did that because they like how their voices sounded on helium and they had a party they needed mood lighting for...



Now back to the real topic... Anthony is there a simple reason for the differences I noticed or is this something that you prefer to remain silent on? I'm all for education but if this crosses into an area you prefer not to disclose we are all mature enough to understand that.

EDIT - I can't read in sequence apparently. Anthony did answer this. See earlier posts.

Anthony Cesaroni

Did you not read my previous “clear as mud” reply to you. Post number 8.

Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

UncleVanya

No - somehow my bookmarks and my navigation caused me to miss it. Oy!
Reading now.

Anthony Cesaroni

Number 8, sorry.

Anthony.

UncleVanya

I have a question about that. With the variance in burn times how accurate is the delay tool for fine tuning the delay to the flight? Is there any known variance that could/should be compensated for in the interest of accuracy or is this good enough as is?

I ask because I know another motor vendor (who shall not be named in this thread) who seems to have a similar method of supplying a single delay and cutting this down with a drill. I have seen some evidence that these estimated delay adjustments are pretty loose





Yes this is quite a bit clearer and essentially along the lines of what I was thinking but the details were helpful.

Anthony Cesaroni

What’s one man’s delay is another man’s timer I suppose.

Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

TRASEC

One small correction: The photo is by Neil McGilvray of Rockets magazine.

That is my rocket in the picture: a 3" Wildman, at 84" long and weighed around 12 pounds on the pad. The rocket did a hard right turn at the top of the pad and climbed at about a 70 degree angle. Went to 6503', max velocity around 900 fps at less than 100 feet according to the ARTS2.

Thanks to Rick Boyette for wrestling it away from the gators and returning it to me.

Bob Schoner

Just Jerry

Once you know what the delay is for a particular case diameter, propellant type, and power range, the offset from that value is very accurate. But a Vmax 38mm 1 grain and Vmax 38mm 4 grain may have (slightly) different baseline delays simply because of varying core sizes along the core or even slight differences in initial Kn values due to discreet available drill sizes.

Rocketman

Anthony Cesaroni

No and actually there is hardly any variation in burn since the nozzle erosion rate is very consistent. The resulting delay times are quite accurate. All tested well within specification otherwise they would not have been certified.

Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

UncleVanya

Anthony - thanks for the confirmation. I don't mean to be ornery but given the number of tests done for certification I'm not sure that any degree of accuracy can be implied from the test results obtained on the part of the certifying agency. If we assume they test 1 of each delay choice they are already far in excess of three motors with your adjustable delay. Even if they only pick a single random value how do they get statistically sound information from three tests? (Sorry is my statistical bias showing?)

The certification tests are just to keep manufacturers "honest". I don't think we can assume a great deal of accuracy from 2-3 motor burns vs. the number you as a manufacturer must do long before going for certification. Consequently I have much more confidence in your testing than certification tests.

Thank you again for participation in this discussion. It's nice to have a manufacturer who is willing to speak up about their products interactively here.

jsdemar

3 motors of each delay are tested, or 2 of each for >=M motors.

The CAR Testing manual is here:
http://www.canadianrocketr...Motor_Testing_Manual.pdf

The new NAR S&T manual is based on the CAR manual and is here:
http://www.nar.org/SandT/docs/ST-MotorTestingManual.pdf
(see 10.1 for Adjustable Delays).

NFPA 1125 8.1.7(b) "No delay time shall be measured to have a variation greater than 1.5 seconds or 20% (which ever is greater, but not to exceed 3 seconds) from the labeled value."

-John

Anthony Cesaroni

We test delays on an ongoing basis for QC for starters and more than one setting is used in certification. In addition we test a wide range of settings during development so I think one can conclude that they are accurate, conspiracy theories notwithstanding.


Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

UncleVanya

John - this works rather better when you have set delays. What happens with variable delays like the CTI and LOKI motors use? Do they test three at each possible setting?

ddmobley

Gee Bob, we just can't give you any credit, can we? Thanks, I edited the article.

Anthony Cesaroni

I can only speak for our products and manufacturing methods but Jack Kane of NAR S&T was present for the joint CAR/NAR certification session when our infinitely variable delays were first certified. He reviewed all of the curves and statistical data and found them to be accurate, repeatable and well within standards. Jack is an MIT faculty member and has an impressive aerospace background. I think I’d believe him.



Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

Anthony Cesaroni

My IT manager just confirmed the error has been corrected on our web site as well. Our apologies.

Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

UncleVanya

Anthony - thanks again for the context. I'm not saying that these are NOT accurate. I'm asking John (and you) what the effective testing model really is. With infinite delays you obviously cannot test all delays that are an option. What is the practical model. The CAR manual states 3 of each delay with a minimum of 11 motors. But "each delay" is where my confusion lies.

I repeat - I am not trying to imply these things do not work. I am saying that I am not sure that certification is adequate to answer the question of accuracy - the motor vendor's own testing is bound to be more accurate statistically. Even 3 motors at a given delay would not provide much statistical certainty with such a high level of allowed variance in the standard.

Anthony Cesaroni

2 points can only make a line. 3 points can make a line or a curve. Besides, do you realize that the temperature on the flight line that the motor is exposed to can vary the burn rate of the propellant as well as the delay time significantly? We qualify and certify HPR motors at 70 degrees F. If you run the motor at 90 F for example, the propellant burn time will decrease and the delay will be longer due to the shorter Pc action time. The opposite is true in cold weather. That’s why our commercial/military motors have temperature/ballistic tables. HPR/NFPA only requires one temperature for characterization.

The certification methods have been demonstrated and are accurate. It’s a component in a low cost sport rocket motor not a precision pyrotechnical fusing device. Regardless its accuracy and characterization are exceptional. Why are you questioning this at length? Conspiracy?


Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

propellanttech

Anthony,

I follow the reason for UV's questioning.

For sake of argument, your reply about temperature affecting the burn rate of the propellant and delay is the focus.

We know the certifying methods only require a single temperature burn for certification. But that doesn't help the typical rocket flier when the shock cord zippers his airframe or shreds his chute.

I think what UV is asking.......What is the typical variance of delay dependent on temperature. Do you have a curve?

This would help the rocket fliers in winter, and on those days, there isn't enough water to drink.

I would like to know, just for informational purposes. We would have some basic rule about adjusting the time, based on temperature.

James L

Just Jerry

Anthony seems defensive in this thread, and probably not justified. Nobody was attacking him, his motors, their accuracy, etc. And saying a guy from MIT checked everything simply does not fly when the statistical sample is 3 and the criterion for success is +/- 1.5 seconds or 20% whichever is GREATER. He could be a moron and the same criterion would apply.

NAR/TRA/CAR is in effect pass/fail testing.

That said, the question about not only delay variability but also the baseline delay time claim, around which the allowed variability floats, seems to be the question. Let's not let Anthony take off on a rant, and send email bombs , thinking anybody is in any way questioning the product quality.

To me the original question was about what the delay is BEFORE you begin modifying it with the tool, ASSUMING the tool itself modifies accurately. I essentially verified that in practice the tool does indeed modify accurately. Anecdotal evidence I agree, but given the sheer number of flights I have witnessed and done, good enough.

Now if there are variances with temperature, the biggest culprit is differing motor burn times changing the baseline delay (tail wagging the dog). There are also possible differences in motor length if the same fixed delay length is used in each of 1G 2G 3G 4G 5G 6G due to the factors I posted and others.

Bottom line I think is what I concluded. In practice the "modal" delay for a given range of certified motor is going to vary from the "certified" delay to a degree (within allowed bounds). I think consumers posting experienced delay times in differing altitude and temperature conditions and concatenating them on a website would prove very interesting, especially considering the excellent batch quality of CTI as compared to most past certified motor brands.

Just Jerry

jsdemar

They're tested at the longest and the shortest using the standard 3 samples each. Then they're tested at other delay settings in between, for a max of 10 motors. This is explained in the NAR testing manual that I referred to in my previous message; I assumed if you were so adamant about this subject that you would have looked at section 10.1 which I pointed out.

During the time around apogee, there's about 2 to 3 seconds with fairly slow vertical speed (check a simulation sometime). This is the same magnitude as the motor delay uncertainty, so all is well.

If you want to be sure of an ejection event near apogee, use an altimeter ejection (or MAD) with the motor as a backup, guessing on the long side for the motor delay. This is what I've been doing for about 15 years now.

-John

charger 2039

The J-1055 is a very nice motor i did a demo at the Winter Nats on my Copmetitor 3, 5,688 feet

UncleVanya

John - in this case I looked at the CAR motor testing manual since this topic was specific to CAR certs. The wording in the CAR manual was confusing - test at all delays is not possible with infinite variability or even assuming testing at every setting on the delay tool. My latest question was specifically which delays (in a variable delay system) get tested and how. I think you have answered that question - unless CAR and NAR differ in this - and the answer is that they test the longest and shortest and a few in between. Now that I think about it you said 10 motors max - but the CAR manual simply states "3 of each delay" for high power motors <= 5120 Ns.

I think everyone assumes an agenda here - and there is not one. Idle interest leads to questions from time to time. I was curious if there was any known variance on delays depending on the motor burn rate and pressure using the style delay CTI uses. According to Anthony once baseline is established the delay modification is predictable and linear and has been tested. I made the comment that based on my knowledge of stats - 3 samples is a poor sample space and would not lead to tight agreement between tests and results - but that the motor vendor would likely have good data and be able to affirm the results.

This is not a passion for me. Just a curious romp down the lane trying to learn how motors work and are tested.

Thanks for your response.

UncleVanya

Curiosity and Learning. Simple answer - don't look for shadows here.

jsdemar