29mm to 38mm seems like a big jump

[techrat]

This is what I’d like to do, except I’d also like to keep the build light enough that I could test-fly on a G prior to certification. I’m a bit on the cautious side and a rocket like that would have a number of unknowns to begin with.

There are a number of kits out there that state they are "perfect for L1" (search the archives on this forum), but they should all be light enough (if built carefully and not overdone), to be tested out locally on a G motor before you proceed to your H class (L1) attempt. Apogee Zephyr, LOC IV, SBR Fusion, to name a few.

 

[smstachwick]

There are a number of kits out there that state they are "perfect for L1" (search the archives on this forum), but they should all be light enough (if built carefully and not overdone), to be tested out locally on a G motor before you proceed to your H class (L1) attempt. Apogee Zephyr, LOC IV, SBR Fusion, to name a few.

I've seen many of these. I like the Wildman DarkStar Jr. but these are all also good options, probably even better.

 

[Spitfire222]

Exactly. I'm hearing of L1 attempts that fail because they shoot for the moon, and then wind up not being able to retrieve their rocket. Too many people think that extreme altitude is "manly", and rush to join the LDRS club before they really know what they are doing. I plan on playing it safe with a low and slow flight using the minimum motor I can get away with.

It's like when I took the class for my motorcycle license. I was told at the end of the class that everyone was now qualified to ride in circles in a parking lot. Dum-dums then buy the biggest, baddest bike they can afford and promptly wind up as a splat on the road. I bought a small scooter, and worked my way up to highway speeds with the second, larger scooter.

I'm in the same boat, I'm happy to take my time progressing through my hobbies and learning methodically instead of rushing through and attempting things beyond my ability.

 

[waltr]

This thread made my think of a question: do any rocketeers really care about the actual newton thrust of a specific motor, and look down at "baby" motors? I'm getting that vibe from some responses here. I don't see anything wrong with someone being happy/proud that they've moved up an impulse range by using a "baby" motor versus a "full" one of the same impulse class. It's a range; a "G" is a "G", etc.

I do consider the Total Impulse and depending on which rocket, flying conditions and mission I may want a baby G or a full G (or in other impulse range).
In my 2.5 pound LOC IRIS with DD, a mid-G (AT 29/40-129 case- 110Ns) takes it to 1100-1300 feet. On calm days >2000' on our local field is good so then I want a full G (AT G75 in 29/180 case- 155Ns) for a 1700-1800 foot flight. I would like to fly this on an H but local field is restricted to Class 1 rockets.

On the other side: I have a 3" 2-stage with air start. Need enough push off the pad but do not want to go very high, no DD so prefer <1000 feet. Found an F67 (61Ns) gets it off the pad but not really enough velocity (<100fps) for reliable staging, specially if sustainer takes a bit longer to light. Here a low total Impulse G (AT G74 SU- 135Ns) does exactly what I want. Still not too high when staging but >150fps.

Best you can do is do lots of sims with different motors to learn how initial thrust (Rail speed), average thrust, burn time and total impulse has on a flight. Then decide which of the flight profiles fit your field and goals.