Art, the CTI load will light cleaner and if nothing else, it will be easier to clean the casing. Loading it will also be a *lot* faster.

I personally make every effort to fly loads other than AT for reasons that I'll be glad to share in person sometime.

It would appear that they both have a lot of "grunt".

I would lean towards the I600 - incredible motor, lots and lots of punch, and a little cheaper than the CTI load. It'll get your rocket up and moving just fine. Of course, the CTI is awesome too - both of them would do great, but my preference is the I600 (I have more experience with it too).

Personnally I would recomend the CTI as I agree with John in that it is a much easier faster lighting motor. Easier assembly and clean up as well as I belive the hardware is lighter to. Both are roughly the same in Ns to not make much difference. To name some others though.. How about the Loki I405 or even the New Loki I430. They are less Ns but very powerful for their sizes. Another would be the AMW I357. Again not as much Ns as the CTI or the AT but all great fast hard kicking motors. If youve never seen the I405 Loki or even heard one they are awesome. Sound like a lot larger motor then they are. Loki runs the motor at over 1500psi. A real sledge hammer.

Definitely - the I405 is awesome, but it might not get the rocket high enough in this case. It's only around 500Ns, though it kicks about as hard as the I600.

Total/average Newton Seconds are not always everything.. Ive seen PLENTY of smaller motors with less total Newtons out lift larger ones. Its all dependant upon when they use those newtons up. The I405 Happens to do it hard and fast.(the reason why they sound like a K motor to) The new Loki I430 is another one that has more total Newtons then its white formula brother but doesnt run at near the pressure as the I405. They are both fairly fast burns at 1.2 to 1.5 seconds. The I405 was designed to be a bowling ball loft motor. Yet to come from Loki in the near future (or as a little birddie told me with the inside info) is some very new cool Loads. Some that will be in the Perfomance ranges of W9 and other cool stuff.

I think that it will have to be the Cesaroni I540 White Thunder. Looking at the TMT certification list, it shows the I600 with only 597.3 Ns and the I540 is at 635 Ns. I had considered some of the other motors but they are not as big as the I600 and the I540 so that is how I narrowed it down to those two. Plus, I didn’t think about the fact that the Cesaroni hardware is lighter, that is a good thing in this situation. I think that the I540 beats out the I600 in this round. Thanks all!

Art

Total/average Newton Seconds are not always everything.. Ive seen PLENTY of smaller motors with less total Newtons out lift larger ones. Its all dependant upon when they use those newtons up. The I405 Happens to do it hard and fast.(the reason why they sound like a K motor to) The new Loki I430 is another one that has more total Newtons then its white formula brother but doesnt run at near the pressure as the I405. They are both fairly fast burns at 1.2 to 1.5 seconds. The I405 was designed to be a bowling ball loft motor. Yet to come from Loki in the near future (or as a little birddie told me with the inside info) is some very new cool Loads. Some that will be in the Perfomance ranges of W9 and other cool stuff.

The total impulse is exactly and directly proportional to the momentum change of the object, aside from gravity and drag losses. More total impulse almost always means higher total altitude in slower flights (faster ones have more drag losses, and therefore are more dependent on other things too). Yes, the I405 has a lot of grunt, and would definitely lift it safely, but the extra total impulse in the I600 or I540 would add quite a bit of total altitude to the flight, giving better chances of the parachute deploying properly.

Total/average Newton Seconds are not always everything.. Ive seen PLENTY of smaller motors with less total Newtons out lift larger ones. Its all dependant upon when they use those newtons up. The I405 Happens to do it hard and fast.(the reason why they sound like a K motor to) The new Loki I430 is another one that has more total Newtons then its white formula brother but doesnt run at near the pressure as the I405. They are both fairly fast burns at 1.2 to 1.5 seconds. The I405 was designed to be a bowling ball loft motor. Yet to come from Loki in the near future (or as a little birddie told me with the inside info) is some very new cool Loads. Some that will be in the Perfomance ranges of W9 and other cool stuff.

The total impulse is exactly and directly proportional to the momentum change of the object, aside from gravity and drag losses. More total impulse almost always means higher total altitude in slower flights (faster ones have more drag losses, and therefore are more dependent on other things too). Yes, the I405 has a lot of grunt, and would definitely lift it safely, but the extra total impulse in the I600 or I540 would add quite a bit of total altitude to the flight, giving better chances of the parachute deploying properly.

I was speaking in general and not of this situation. But sometimes people look at the TOTAL newtons given by a motor and believe that it would imply as you are speaking

Actually I think you completely over thought what I was saying and misunderstood completely... I was speaking in general and not of this situation of the I600 or the I540 or any others mentioned. if you are looking at the TOTAL newtons given by a motor and believe that it would imply as you have stated thinking so would be a misconception as it is not the case. More total impulse doesn't always mean more altitude nor does it mean even a safe or stable flight. let me see if I can explain this in a better way.

If you have 2 motors in the same impulse class. Lets say H motors(160.1 to 320 ns)...like the Aerotech H669 vs the H112 (even for that matter an I motor in a higher Impulse class yet like the I161). Both are H motors in (except for the I of course) the impulse class they represent, and the H112 has 280ns vs the H669 that has 220ns. By all means of your statement Quote
"The total impulse is exactly and directly proportional to the momentum change of the object" and because the H112 has 60ns more it should be more powerful and achieve a higher altitude with safer deployment because of its higher total impulse. BUT what I was referring to and stating previously that is not the case. Why? because a rocket that weighs in at 15 to 20lbs needs(should have if your flying smart) 5x thrust to weight to have a stable flight let alone achieve altitude. Thats something that neither the H112 or the I161 for that matter are going to be capable to do even though they have higher total impulse over the H669. Thus showing a smaller total impulse motor can out perform a higher total impulse motor in the Altitude and safety factor of a flight. Here is what I was trying to point out..........A smaller motor of given total impulse can outperform a motor of higher Impulse just depending on at what area in the thrust curve it uses it in. The H669 does it all up front. Of course its a better choice for a heavy rocket. The H112 couldn't even fly it as it has no initial kick to get it off the pad safely. While at the same time the H112 would be better suited for a much smaller rocket the H669 can still fly in the smaller rocket. Maybe at that point not as high but plenty safely to deploy a chute at any given field.

Gravity and drag losses can never be taken aside. as for what is weight but yet Gravity's effect of downward pull on us and everything we see. because we don't launch from the moon we have to always take that into effect. I say it every time about Altitude flights the most key important factor is mass and having it Optimal in design. Drag does offer some effects but the strongest one is gravity. Look at the space shuttle at lift off. She is like a flying house. Not all that aerodynamic. the main thing they fight is gravity and thats why all the big power from the SRB's is added to its liquid motors.

Anyhow, Art good luck with your project and I cant wait to see it all in the works.

Note that I was stating that in the case of the rocket having safe thrust off the pad, which in this case both motors do, then the total impulse should be the next thing looked at. Obviously, if the motor cannot safely lift the rocket, then it is not a good choice, regardless of the total impulse.

8) For my 2 cents worth, in a 1-2-3 world, I would go I540, K660 or L730, and finish with a lovely M1400. Pro all the way! 8)

The motor mount is only long enough for the M1297W. Gotta save weight!

Art

Pro all the way!

Tim, we talked about the price of AT RMS casings and reloads, we should talk about CTI and compare costs. You showed me the EASE of using Cesaroni... I don't want to head off in the wrong direction. CTI motors are really impressive... and moonburners with an M burn of over 14 seconds! Suh-weeet! Man, I really hate to say this, but I really don't care about the color of the flame, only performance. So if Cesaroni hasn't joined the rainbow league, that's fine. And, the fact that you can use CTI reloads in AT RMS hardware is really versatile. That way I can use the RMS casings I already have. And, if I decide to go with AT RMS, I can still use certain CTI reloads, in certain casings, right? The way this relates to Art is that I can't find the dimensions of CTI casings, and I want to keep my next booster section long enough to handle everything (including hybrids). You know where I can find the info?

Pro all the way!

Tim, we talked about the price of AT RMS casings and reloads, we should talk about CTI and compare costs. You showed me the EASE of using Cesaroni... I don't want to head off in the wrong direction. CTI motors are really impressive... and moonburners with an M burn of over 14 seconds! Suh-weeet! Man, I really hate to say this, but I really don't care about the color of the flame, only performance. So if Cesaroni hasn't joined the rainbow league, that's fine. And, the fact that you can use CTI reloads in AT RMS hardware is really versatile. That way I can use the RMS casings I already have. And, if I decide to go with AT RMS, I can still use certain CTI reloads, in certain casings, right? The way this relates to Art is that I can't find the dimensions of CTI casings, and I want to keep my next booster section long enough to handle everything (including hybrids). You know where I can find the info?

I can help you there Bruce.. PM me and I have the data for you. Thats how ive designed all of the majority of the rockets Ive ever flown.

AFAIK, all Pro75's fit in the equivalent AT hardware, and that might be true about Pro98 as well (not quite as sure there). So, buy AT hardware for 75mm, and then you can fly both Pro75 and AT loads in one set of cases.