How low can you go?

For a hypothetical l3 flight, what standard manufactured kit with nar approved motor would give you the lowest altitude? Is it possible to do l3 in 5-6000 feet? Just wondering, thanks.

I don't have any particular kits/motors to recommend, but I imagine it would be pretty easy to come up with a combination. Start with a heavy, high-drag rocket. Think large diameter, big fins, shorter/blunter cone, leave the fin edges un-profiled. Use a motor that has just enough INITIAL thrust to make it stable off the rail, but no more, and a short burn at that. A longer rail will make this easier to configure.

s6

Could cover it in shaggy fur. But then you're dancing on the odd roc rule.

I'd think a fat heavy rocket should be able to do it.

DizWolf said:

Could cover it in shaggy fur. But then you're dancing on the odd roc rule.

I'd think a fat heavy rocket should be able to do it.

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...what's odd about a furry rocket? My cats make sure to include their furry component to most of my rockets but I don't think they will go along with the idea of using them as payload ballast...

I simmed a 6" darkstar for L3, adapted to 75mm and flying a low M. You can keep it under around 7K with a 75mm 5% M. A 10 inch or even 12 inch rocket could definitely be kept low.

I've seen a few rockets flying on M's that topped out at 2k' or less, a large tube fin rocket would be a good place to start(IMO).
Rex

There was a thread a few months ago about something like a 22" sonotube rocket used for L3, and it was a pretty cool low and slow flight --- not a kit, obviously.

EDIT: Here, found it. The thread is very long, but here is one of the videos of the flight for your inspiration: https://www.rocketryforum.com/showt...ania!!!-LPR!-MPR!!-HPR!!!&p=721464#post721464 Lots more info in the rest of the thread.

Bandman444 was around 800' on his L3... That was one cool flight.
[VIMEO]98698151[/VIMEO]

WoShuGui said:

Bandman444 was around 800' on his L3... That was one cool flight.
[VIMEO]98698151[/VIMEO]

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That's awesome! Do you have a link to the build thread by any chance? Edit: never mind, Thirsty linked it earlier in the thread. Very cool!

jlnel said:

For a hypothetical l3 flight, what standard manufactured kit with nar approved motor would give you the lowest altitude? Is it possible to do l3 in 5-6000 feet? Just wondering, thanks.

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Scrap the kit, go scratch. My L3 was with a paper rocket, Kosdon M2250 to 4500'

SCrocketfan said:

That's awesome! Do you have a link to the build thread by any chance?

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Here it is: https://www.rocketryforum.com/showt...-o-mania!!!-LPR!-MPR!!-HPR!!!&highlight=squat It's a GIANT Squat!

ThirstyBarbarian said:

Here it is: https://www.rocketryforum.com/showt...-o-mania!!!-LPR!-MPR!!-HPR!!!&highlight=squat It's a GIANT Squat!

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That's great, now I'm getting ideas… Maybe a 20 inch Magg...

Haha!!! Thanks guys for the share! It was one hell of a project.

Why not build a saucer? A darn big saucer...

rharshberger said:

Why not build a saucer? A darn big saucer...

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Been done....but alas, now not allowed for certs

DizWolf said:

Been done....but alas, now not allowed for certs

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Its sad indeed:sad:....but it would still be way cool

Some one did a really cool long burn N in a saucer for a night launch. There is a great video of it that I cannot find at the moment.

Wow, some great builds! Im starting to like the scratch build idea. Anyone have a OR sim they would share? Im not ready for l3 buld would like to start planning!

At Desert Heat last year a young lady form Phoenix did her level three with what appeared to be a 12 inch diameter Crayola Crayon. It didn't appear to get over two-thousand feet. She got her cert.

Be wary of thrust to weight ratios. An 800' flight based on a heavy rocket is likely under the allowable threshold.

Old-school East Coast L3's used to be in the 5,000'-6,000' range using M1315's or M1939's to stay under waivers.

I don't who Bryce is, but that one beautiful flight all the way.
Congratulations Bryce!

patelldp said:

Be wary of thrust to weight ratios. An 800' flight based on a heavy rocket is likely under the allowable threshold.

Old-school East Coast L3's used to be in the 5,000'-6,000' range using M1315's or M1939's to stay under waivers.

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Isn't that what the M4770 and N10000 are for?

CarVac said:

Isn't that what the M4770 and N10000 are for?

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I've got a M4770. Don't forget the M6400!

terryg said:

Some one did a really cool long burn N in a saucer for a night launch. There is a great video of it that I cannot find at the moment.

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This one? :grin:
[YOUTUBE]rsARPcfpPM4[/YOUTUBE]
(Search N800 for more with this motor.)

patelldp said:

Be wary of thrust to weight ratios. An 800' flight based on a heavy rocket is likely under the allowable threshold.

Old-school East Coast L3's used to be in the 5,000'-6,000' range using M1315's or M1939's to stay under waivers.

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When the Kosdon M2240 became available, low lob shots became possible. The lowest I saw was a full scale Phoenix. It didn't quite make 1000 feet.

Rocketjunkie said:

This one? :grin:
[YOUTUBE]rsARPcfpPM4[/YOUTUBE]
(Search N800 for more with this motor.)

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I suspect this will cause a stir.op:

The drag of larger diameter rockets keeps the apogee low more so than weight so fat rockets do not have to be excessively heavy, and lighter (lower sectional density) rockets slow down faster anyway due to lower retained momentum. Several quick sims show that the average 20" rocket will stay under 2500' on any M, a 16" rocket will stay under 3000', a 12" rocket will stay under 4000' and a 10" rocket will stay under 6000' on any M, and many will apogee at ~1/2 that altitude on a minimum M.

Sonotube rockets are strong (in these diameters glass is not required) and cheap to make so have at it. Another advantage of a big fat rocket is that it is easier to see at apogee and track on the way down...... The only disadvantage is that you will most likely have to make your nosecone.....

Bob

Full scale Phoenix (not a kit though) did 1400' cert flight on an M at MWP3. Was on the cover of Extreme Rocketry Issue 52. Kurt

The drag of larger diameter rockets keeps the apogee low more so than weight so fat rockets do not have to be excessively heavy, and lighter (lower sectional density) rockets slow down faster anyway due to lower retained momentum. Several quick sims show that the average 20" rocket will stay under 2500' on any M, a 16" rocket will stay under 3000', a 12" rocket will stay under 4000' and a 10" rocket will stay under 6000' on any M, and many will apogee at ~1/2 that altitude on a minimum M.

Sonotube rockets are strong (in these diameters glass is not required) and cheap to make so have at it. Another advantage of a big fat rocket is that it is easier to see at apogee and track on the way down...... The only disadvantage is that you will most likely have to make your nosecone.....

A 10" Polecat Goblin is a short fat inexpensive kit that would meet your needs. https://www.polecat-aerospace.com/kits/10_inch_kits/goblin.html I calculate an apogee of ~3100' on a Pro98 M1560....

Bob

On the subject of sonotubes, does anyone know how much they weigh per inch? And what are their accurate dimensions? For example, what would a 6-inch length of 12" sonotube weigh, and what are the inside and outside diameters?

If anyone can provide that info, I'd appreciate it. Thanks!