Lakeroadster's "Level One"

[lakeroadster]

I've been toying with getting my L1. I've spent some time on a scratch design / build rocket to reach that goal. I'm naming it "Level One".

• 4" diameter with a redwood nose cone, and recovery is via a rear eject combo of spool / motor mount.
• It's a pig, intentionally, designed to apogee around 1,000 feet and work well with a 6 second delay G motor.
• A 3-1/2" inner tube allows for TTW construction

So what do you think? Does this look like a rocket that would be acceptable to NAR as a L1 attempt?

Your advice is sincerely appreciated.

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[dhbarr]

Seems plausible. H97, H115, H135, other?

 

[Sandy H.]

I don't see why not. What does it sim on the intended H motor? I think a lot of people cert on fairly short rockets and I like a functional rear-eject system. One club member flies the 'poop chute' option quite often.

Sandy.

 

[hobie1dog]

Go for it.

 

[lakeroadster]

Seems plausible. H97, H115, H135, other?

I don't see why not. What does it sim on the intended H motor? I think a lot of people cert on fairly short rockets and I like a functional rear-eject system. One club member flies the 'poop chute' option quite often.

Sandy.

H97 ...

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[jmasterj]

< 45fps rail speed on the H97 is pretty questionable. Have you considered your glue and paint weight? Adding more weight won't improve that situation.

Looks fun, though! Could change it just a tiny bit and have an upscale of your Warhawk.

 

[dhbarr]

H97 ...

View attachment 542764

Should be a nice gentle up-and-down with good smoke, as long as you've very little breeze

 

[techrat]

6 fins? The spool is inside the 3-1/2" Tube, I assume, otherwise the rear eject would get hung up. With this design, I am now realizing for the first time that with rear eject in this fashion, the entire outer airframe is the "nosecone", and the actual airframe holding the motor mount is located inside this outer airframe. Neat. I'm going to have to start looking into how to do this properly, as I want to build a WWII Bomb rocket, and need it to have rear-eject so it parachutes down looking like I'm dropping a bomb on you.

 

[MadRocketer]

H97 ...

I like the H135 stats better. Quicker off the rod, slower at deployment.
Great design! If I ever finish the one I’m stalled out on…..

 

[Daddyisabar]

There are several H motors under 125g propellant weight that can be used at local clubs like CRASH or COSROCS at the Peyton site. Use KISS technique, 3-4FNC. NO STINKING ODDROCS! Can do any H or I motor at SCORE. NCR or Tripoli Hartsel.

 

[lakeroadster]

I just wasn't happy with the appearance, so here's a variant that uses NASA salvage yard parts.

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[MadRocketer]

I just wasn't happy with the appearance, so here's a variant that uses NASA salvage yard parts.

View attachment 542852

I really like that! If it wasn’t for the cert attempt, I would suggest an escape tower on the nose!
Great design, seems like it could take a fair amount of abuse.
Run with it!

 

[Sandy H.]

I just wasn't happy with the appearance, so here's a variant that uses NASA salvage yard parts.

View attachment 542852

When I saw your first post, I was a little surprised and thought someone must have hacked your account. The rocket was plain by your standards. Now that I see this version, I know its really you!!! Love the changes! Any thoughts about a corrugated wrap or similar little features to be added during the build?

Look forward to seeing it!

Sandy.

 

[lakeroadster]

When I saw your first post, I was a little surprised and thought someone must have hacked your account. The rocket was plain by your standards. Now that I see this version, I know its really you!!! Love the changes! Any thoughts about a corrugated wrap or similar little features to be added during the build?

Look forward to seeing it!

Sandy.

Yep, I understand your confusion.

I spent some time making wraps and applying them to the model to give it more of a NASA look. I like it, but personally... it's been done to death.

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So, for this one I'm going with more of a "Hot Rodded" version, instead of the "NASA Restoration" version.

I refined the fin size a bit and added a skirt to the spar urethane coated redwood nose cone. At this point I think I'm ready to source materials and fire up the CAD station.

Anybody have a source for 4" O.D. and 3-1/2" O.D. cardboard tube or do I need to look for shipping tubes?

The conical shapes at the base of the fins should help to increase the base drag. I'm planning a spin test... I'm thinking it'll be more stable than the 1.5 calibers Open Rocket shows.


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< 45fps rail speed on the H97 is pretty questionable. Have you considered your glue and paint weight? Adding more weight won't improve that situation.

Agreed.... I didn't have the correct rod length, I increased it to match the usable length of my 5/16" launch rod and that made the "off-rod" speed mo betta.

 

[lakeroadster]

Use KISS technique, 3-4FNC. NO STINKING ODDROCS!

Did your account get hacked?

 

[Daddyisabar]

Did your account get hacked?

Any official level one attempt brings out my inner "Law and Order" RSO. In the good ole days your witnesses watched you build the motor, always eyeing that checklist. No hanky panky. Fly and certify with a sensible 3-4FNC. Only then go to dark arts, high powered oddrocs.

 

[lakeroadster]

Any official level one attempt brings out my inner "Law and Order" RSO. In the good ole days your witnesses watched you build the motor, always eyeing that checklist. No hanky panky. Fly and certify with a sensible 3-4FNC. Only then go to dark arts, high powered oddrocs.

I guess I'll need somebody to define "sensible", because to me, this fits the bill.

 

[Blast it Tom!]

I guess I'll need somebody to define "sensible", because to me, this fits the bill.

Well, none of this hobby is sensible to my beloved , so there is a wide spectrum of what is "sensible".

I think what the good fellow is saying is, for an L1 attempt, just do the simplest, most reliable possible rocket, then once you have your cert you can go back to your dear ol' oddroc self - but with more power available!

 

[Funkworks]

Hey the fins changed in your last few posts. The one thing I've learned about certification flights is that fins are better off being less "pointy", because they take a hit on landing and we want to reduce the risk that they break. In principle, the first fins you had are less likely to break, because of how a rocket lands. (In the later version, there's a tip that's more likely to break off)

 

[lakeroadster]

Here's a sim to check stability due to fin area loss from the conical pieces at the base of the fins.

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[BABAR]

I like rear eject models. One thing that is tricky and I struggle a bit with is shock cord attachment.

Seems this needs to go in anterior “chamber” between nose cone base and forward (of three) centering rings, all of which are glued only to mount. The shock cord gets blasted by the ejection charge (although you could put a sheet or two of wadding in the motor mount tube to catch the larger particles.)

Nice thing for rear eject is no wadding needed to protect laundry.

The attachment to the motor mount is tricker, I recommend running it BETWEEN the forward centering ring and attaching to second or third centering ring. If you attach it to the FORWARD RING, you may kink your motor mount tube.

 

[lakeroadster]

I like rear eject models. One thing that is tricky and I struggle a bit with is shock cord attachment.

Seems this needs to go in anterior “chamber” between nose cone base and forward (of three) centering rings, all of which are glued only to mount. The shock cord gets blasted by the ejection charge (although you could put a sheet or two of wadding in the motor mount tube to catch the larger particles.)

Nice thing for rear eject is no wadding needed to protect laundry.

The attachment to the motor mount is tricker, I recommend running it BETWEEN the forward centering ring and attaching to second or third centering ring. If you attach it to the FORWARD RING, you may kink your motor mount tube.

300# Braided Kevlar attaches to screw eye.

Replaceable Shock chord runs through Kevlar conduit and a noose slips around motor mount near motor exhaust nozzle. A wrap of tape around the noose ensures the noose stays in place.

Same design as I used on the Red Columbine and the P-40.

 

[BABAR]

Yeah, I should have looked at Columbine build. I knew this wasn’t your first rodeo with rear ejection.

 

[BABAR]

Brilliant idea of using temporary rubber band to hold laundry during insertion, then cutting it. I’ve had rear eject rockets with not nearly as much difference in diameter between mount and body tube where space was tight. Packing those was a family forum unfriendly word.

 

[jmasterj]

What are you making the conical sections around the fins out of?

 

[lakeroadster]

What are you making the conical sections around the fins out of?

Pine. They are 1.32" dia., I can turn them on my lathe out of a ripped 2x4.

 

[lakeroadster]

Updated 2022-11-19: Drawing Set Rev 05

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[jmasterj]

What's the biggest motor you want to fly in this? You may not be able to fit an AT 29/360 or CTI 6G in that length of motor tube. Worth checking, at least. I guess you could always drill out the nose later to make space!

 

[techrat]

If you look at the CAD drawing it seems that Lakeroadster has assumed that all 29mm motors are the same length (Item #13)?
What I see is a 29mm x 95mm(?) which may be an Aerotech F20 (single use) or thereabouts. Most G and up motors go into reloadable tubes, and which tubes you have determine which reloads fit into those tubes. I'm just starting to get into this myself, but I don't think even the popular RMS 29/40-120 takes an H reload making it ineligible for an L1 attempt, unless I'm mistaken. So yes, a longer reload may be required, but again, a "Baby H" should fit into the available motor tube space from what I see.

 

[lakeroadster]

What's the biggest motor you want to fly in this? You may not be able to fit an AT 29/360 or CTI 6G in that length of motor tube. Worth checking, at least. I guess you could always drill out the nose later to make space!

Just the min. to get L1 certified.... an H97-6 is a good fit for this rocket.