Smallest L3 Motor

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M1297W a thing of beauty....

View attachment 308555View attachment 308557View attachment 308556

iirc 37lbs RTF, 7800' max altitude, and 908fps. It jumped off the pad in a blink, the first two photos are consecutive frames.

Hah, you still beat the heck out of my consecutive frames -
hME0pAY.jpg
 
Hah, you still beat the heck out of my consecutive frames -
hME0pAY.jpg

In my case it was entirely the fault of the igniter, it was a custom igniter so the photographer got zero warning beyond the announcers countdown, the countdown went from 1 to rocket moving as there was a small pop and motor instantly went to full pressure. Yours is impressive, was it a minimum diameter?
 
I use video capture, this is a J350W

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You can pick what you want or anything in between.......
 
In my case it was entirely the fault of the igniter, it was a custom igniter so the photographer got zero warning beyond the announcers countdown, the countdown went from 1 to rocket moving as there was a small pop and motor instantly went to full pressure. Yours is impressive, was it a minimum diameter?

4 inch rocket, so nearly but not quite minimum. Although the camera lacks the clock resolution to tell for sure, I figure I must have let up on the trigger. It certainly was an awesome flight, but a little bummed to miss a liftoff shot of my L3 flight.
 
Don't let these guys discourage you. You are planning and that is good. I did this for 12 months before I built my rocket.

One recommendation: plan the rocket then buy the motor. You need to know the weight before you pick an average thrust. Impulse is important, but not as much as the average thrust and burn time to keep in on a small field. A higher average thrust is also not that important with a heavy rocket with lost of drag.

I simulated my flight hundreds of times before I purchased a motor. I tested flights with about every M motor I could purchase.

What rocket are you planning to fly and what is it's estimated final weight? Keep in mind that most flyers add about 10% of weight to their level 3 unexpectedly. I expected mine to weight about 52 pounds based on my build plan and it came in at about 58.

I hope this helps. I can SIM it for you if you send me the rocket type and you projected weight.

I planned mine over 7 years due to a period of lack of interest.
I had signed up for a Procrastinator's Anonymous class but I put it off another year.
 
It would not be number of grains. I am not certain if it was better density or smaller core

As I recall, it was a slight shift in density or chemical source that surprised everyone when TMT went to re-cert the L-1297 that it bumped over the threshold and was now a 0-1% M....
 
With the M650 you will have a slow liftoff unless you build a light rocket. That long burntime under a gravity turn on a slow rocket can put you a long way downrange. Launching in anything but calm conditions would exacerbate the problem.
 
With the M650 you will have a slow liftoff unless you build a light rocket. That long burntime under a gravity turn on a slow rocket can put you a long way downrange. Launching in anything but calm conditions would exacerbate the problem.

It's only 9 seconds, that's nothing.
I did my L2 with a K125, 20 second burn.
 
But with new motors being introduced, the answer could change. Is it considered improper to revisit a question?
Well, for the sake of general knowledge, of course not. I was just pointing out that the OP probably already has his answer.
 
But with new motors being introduced, the answer could change. Is it considered improper to revisit a question?

Actually, I am considering an L3 attempt myself ( Searching for motor info when I found this thread ) . . .

6" diameter PML Phenolic ( doubled with coupler ) . . . 10 - 11ft long . . . Scratch-Built . . . 75mm mount . . .

Looking for a "nice, gentle motor" . . .

Considering AT M650 / GORILLA M745 / AT M1297 / CTI M1101 . . . Also, looking to remain Sub-Transonic, at all costs !

Dave F.
 
I used the CTI M1101 for my L3. The rocket was a stretched Formula 150 and weight 52 pounds on the pad.It flew to 5800' AGL. It had a nice white flame and good smoke trail on take off.
M86RsfP.jpg
 
Actually, I am considering an L3 attempt myself ( Searching for motor info when I found this thread ) . . .

6" diameter PML Phenolic ( doubled with coupler ) . . . 10 - 11ft long . . . Scratch-Built . . . 75mm mount . . .

Looking for a "nice, gentle motor" . . .

Considering AT M650 / GORILLA M745 / AT M1297 / CTI M1101 . . . Also, looking to remain Sub-Transonic, at all costs !

Dave F.
Sounds like you have spent some time with this already.

This is feeling like a 4 grain , 75mm motor that is an M and not an L... The longburn M650 may start off gentle but will keep building velocity .. and end up going fairly fast before apogee. Use Thrustcurve with a mass estimate and look at the velocity and G of the flight as well as they predicted altitude.

Dont get to bogged down on the most ideal motor.. Motor availability, hw availability, $$$ , flying season may all influence your final selection more than anticipated.

Doing a test flight with a smaller punchy motor may alleviate some fears of the velocity and Gees your bird can take....also seeing the electronics work for a successful flight is always welcome.

Two of my rocket buddies went with the AT 1500G .. Punchy but on the lower side of Ns like the M1101..maybe not your ideal but may add to your short list

Kenny
 
Sounds like you have spent some time with this already.

This is feeling like a 4 grain , 75mm motor that is an M and not an L... The longburn M650 may start off gentle but will keep building velocity .. and end up going fairly fast before apogee. Use Thrustcurve with a mass estimate and look at the velocity and G of the flight as well as they predicted altitude.

Dont get to bogged down on the most ideal motor.. Motor availability, hw availability, $$$ , flying season may all influence your final selection more than anticipated.

Doing a test flight with a smaller punchy motor may alleviate some fears of the velocity and Gees your bird can take....also seeing the electronics work for a successful flight is always welcome.

Two of my rocket buddies went with the AT 1500G .. Punchy but on the lower side of Ns like the M1101..maybe not your ideal but may add to your short list

Kenny

A while back. someone posted a comparison of various motors in a 5" diameter / 30 lb. rocket . . . Below

Dave F.

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simfile2138_650x350lbs.png


simfile2165_650x350lbs.png


simfile2209_650x350lbs.png
 
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