My dad's L2 project....

[Neil]

Well, the parts are coming in for my dad's L2 project. Today we got the shock cord, heat shield, motor retainer (slimline), and motor adaptor. And next week the body tube is coming in. We already have the foam for the nosecone, but we are going to need some more glass. GRRRRRR. we cant do much before the glass comes....

So heres the plan. No electronics (I saw Bill Spadafora's attemt...). I am gonna make him the chute, nosecone, and glass the tube for him. It will have a 4" diameter glassed mailing tube, 60" long, a 15" (I think....) nosecone, a 54MM motor mount, plywood fins (He just went with the ones Rocsim automatically put on for him. Didnt change them a bit. go figure.). The shockcord is 10 yards of tubular Kevlar (thats great stuff....), and the motor mount will be made of fiberglass (no mailing tube in there. Theres plans on how to make em on the Aerocon website). The fins, centering rings ETC are gong to be made of 1/4" 5 (or 7, I forget) ply birch plywood. Ill try to post the Rocsim file. Tell me what you think!

Oh, yeah. I think it will go about 1K-2K feet on a J420R.

 

[daveyfire]

I'd be worried about ripping the fins off on a 54mm motor bigger than a J275W. If you shorten the span a little bit, they won't have such an opportunity to break in flight or during landing. Other than that, it looks like a good plan! Let us know how she flies.

 

[Neil]

Tell that to my dad.... He likes the big fins. Ill try to talk to him about it, though. and if he doesent want too, Ill try modifying the sim and hope he doesent notice That proabably wont happen, though. The cert will proabably be on a J420R or a J350W. Though it would be a good idea to make sure its strong enough for a very small K, just in case he starts feeling ambitious sometime....

 

[Stymye]

... isn't the object of a cert flight to prove the person actually flying the certs, complete construction and recovery skills?
not someone elses

 

[Neil]

Well, he could buy a nosecone from PML, and buy a pre-glassed tube from em too. This just saves money, and gives me something to do. He has fiberglassed many things in his life, and he is really sick of the mess. He just doesent want to spend $200 on pre-glassed tubes, thats all. Especially when he can have me do it for $150 less. If you ask me, its just the same as buying a pre-glassed kit, or buying pre-glassed tubes. I am not doing any of the CONSTRUCTION. That wouldent be good. He has to build it, I think it is OK for me to make some of the parts for him.

 

[Neil]

Here is the rocket with a smaller version of the fins. Do you think they are still too big, or are they OK now? What would be the optimal size?

 

[Stymye]

Neil
sorry ,my bad , I kinda got the feeling you were building the rocket from your post,
nope,, I don't see any reason why you shouldn't glass the tubes and make the cone........good luck to the both of you on the L2!

I wish when Daniel (my son) was your age, he knew how to glass! lol

 

[Neil]

Thats quite alright. (MMHPR Custom glasswork!!!).

I bet you do wish he could glass! Be a good "paid chore"! LOL.

 

[doxiedog315]

What kind of mailing tubes are you using?The ones i find,have very large seams.(staples)........jerry.

 

[loopy]

Originally posted by doxiedog315
What kind of mailing tubes are you using?The ones i find,have very large seams.(staples)........jerry.

That's where the glassing comes in - covers the spirals...

 

[Neil]

Hmmm.... Large seams? Uh oh... Oh well. We are glassing them anyway. It shouldent make too much of a difference. (I hope...)

 

[n3tjm]

Neil,

Does he plan to certify at a CMASS launch? I plan to buy a RMS 38/720 case soon, and I would like to order some loads... I would like to split the shipping as many times as possible. Pm me if you like me to get your Dad his motor.

 

[mark.simpson]

Originally posted by doxiedog315
What kind of mailing tubes are you using?The ones i find,have very large seams.(staples)........jerry.

I've got a few mailing tube rockets. I hate prepping tubes, so I cover them with contact paper, or more recently, wood veneer.

 

[Justy]

Neil, you may want to try a smaller parachute. I simmed it on an AT J420R as you suggested you'd be flying (which is a 38mm motor, so you've got an adapter, right?), and with a 10 MPH wind, it does indeed reach 2,000 feet but you and your dad are going for a long walk to get the rocket back. If you can't find the rocket after the flight, you don't certify... another advantage of the smaller 'chute is that it'll be cheaper. Pre-made chutes are expensive, and rip-stop nylon fabric to make your own isn't cheap either.

What is the purpose of the "body tube" object in the nose cone? Is it an electronics bay for future use?

You can shrink the fins until the static stability margin, with motor loaded, is somewhere between 1.0 and 2.0 (right now it's up around 8). Then, you can make them even smaller if you use 4 fins instead of 3.

Once you've got the tube and nose glassed, go back into RockSim and manually change the weights of those pieces ("mass override"). The stability may change, since these parts are going to be heavier. Plus, it'll give you a more accurate altitude estimate.

You score a million bonus points in the game of life if you do a Carl Tulanko style photojournal of the assembly!

 

[Neil]

Well, the sim is way off on the CG for some reason. The nose is too heavy in the sim or something. Ill fix it sooner or later. (as in tonight...) The chute is just what Rocsim calculated during the oridonal (now thrown out) design. It was much heavier. So yeah, the chute will be smaller. Besides, we have 600 acres of blueberry barrens to recover it on!


So your getting a LEUP too, doug? no point in gettin the case if you cant buy the loads.... I know they are Easy Access loads, but all the dealers are refusing to take orders without LEUPs now, as I am sure you know.

No, my dads not certifying at CMASS. We have had too many bad experiences recovering L1 powerd birds at that field, an L2 is too risky for our tastes.... he is gonna cert at Cherryfield. Great place, Cherryfield. 600 acres of open blueberry barrens, with free snacks! (blueberrys. Huge, succulent, proabably-pesticide-ridden fruits... Ever so delicious, though slightly over-ripe during the labor day laung Its after the picking season, or so I figure. Most of the quadrants have been plucked bare, but they always miss some, which are very quickly picked bare ). Its our preffered place to launch. I was silly enough to launch my little ASP clone (1.5" tube) on a G64 at CMASS... Barely recoverd it. The only reason I got it back was cause I used a longish (for my ASP) delay and a tiny chute. It actually landed upwind from the pads (I had it angled way into the wind), but only because it arced over past apogee and fell for about 3 seconds before popping. I shudder to think what woulda happend to one of those houses if it hadent popped.... Proably woulda put a hole through a roof! Cherryfield is much better, though. No houses, just a very purty view of some mountains, and open space almost as far as the eye can see!

So, have I sold you on Cherryfield yet?



Yeah, we bought a Slimline motor adaptor which comes with a motor retainer build in. Looks pretty cool.

 

[Neil]

Heres the latest version of my dad's L2 project. How fast d'ya think a rocket can go down and still be safe enough for a cert? 20FPS? 25?

 

[n3tjm]

Unless anything has changed (again), we do not need an LEUP for Easy Access loads. Some dealers may require them... but that is their decision. I buy from Magnum, and Ross follows the rules.

CMASS is not good for altitude... 3000 feet is my max with Dual Deploy on that field.

 

[daveyfire]

Originally posted by Neil
Heres the latest version of my dad's L2 project.

Now SHE'S a purdy rocket! Build it strong, bring it out west and we'll stick a 3000 Nsec L3000 in it (yes, that is a 1 second burn time)

I bet if you glassed everything, you could bring that down at ~25 fps. Since the fins are angled up from the bottom, as long as you come down relatively straight, the landing stress won't be too bad. Personally, I'd use an R7 for a chute.

 

[Neil]

R7.... Howbout the MMHPR custom equivilant? You remember I do custom chutes.... Im making his chute; we are proabably going to buy the material today or tommorow. Of course I am not going to charge him full price, cause hes my dad and I know we dont have a ton of spare cash after buying a puppy.


25FPS... Thats pretty quick... Howbout 20-22 just to be safe? not like we dont have a TON of room to land it in, afterall.

Doubt we can bring it out west..... and my dad wouldent want a 1 second burn time, either... Though if there is an LDRS out west sometime, we might be able to make it! If we do, I promise you I will get my dad to bring it!


Now.... One more thing.... The name. Any suggestions?

 

[n3tjm]

That rocket says "Javelin" to me...

or you can give it a goofy name like

"$20 a second"

or

"APCP or Bust"

or


"To Much Chili"



… Wait a second… I like that last one… I might use it myself

Oh… go with the J350… Way cooler motor .

 

[Neil]

Too late, my dad likes redline propellant! He wont go with the J350... J420 lookse better to me, too. to each his own, I guess.


Interesting names... Ill run them by him.

 

[Neil]

the airframe just came in the mail! a dozen 60" long 1/8" thick 4" ID mailing tubes. The seams are about 1/32" wide. Very good, cosidering thier real purpose. And dang, these things are strong! I wont even need to glass em for rockets I want to keep light! Were still gonna glass em for my dad's L2 project, but just so it weighs more. The tube already weighs 2.1 pounds. By my best guess (please correct me, I know I am proabably wrong...) it will be between 3 and 4 pounds (jsut the tube) once glassed. Ive got some pics already, Ill post em once I resize the little buggers

 

[Neil]

OK. I got pics! Heres the faraway pic. Notice the super-nice woodstove!

 

[Neil]

And the closeup. Notice the very-thin seams!

 

[Neil]

And the inside of the tube. Not the best of pics, but hey.

 

[havoc821]

Where did you get those mailing tubes from? I'm interested if they are cheap.

 

[Neil]

They would be cheap if you didnt have to buy em by the case. $90 for a case of 12. So really you get a whole lot of tubes for your money, but you might not use them all for a few years.... If you ask me, its a good idea to buy a pack of every diameter from 1.5-5", so you have plenty to work with for years. Only problem is the price......... They are nice tubes, however.

 

[havoc821]

Wow, that is a good price, but it is a little over my budget for a long while. How strong are the tubes compared to phenolic. What sizes did you order? Was it just the 4 inch tubes? How long are the tubes. The reason I am asking all of these questions is because I am interested in these tubes, but I don't have the money to buy a whole case. I was wondering if you and your dad might possibly sell me a tube or two. I would pay shipping and etc. I wouldn't be able to order one for a while if you/ your dad said yes (have to spend my last $17 on paint for my Horizon and a H165R to fly it ). I was just curious and got into that rocket thinking mood again.......... Let me know what you think about that. Thanks in advance!

 

[Neil]

They are 60" long, strong as heck, 4" ID, 4.217" OD (I think. Let me find my calipers and I can give you a definite on that.), and have pretty tight seams. I have never owned a 4" diameter Phenolic tube, but I am sure this is just as strong or stronger! as we have 11 extras (I know I am not going to have the funds to make 11 4" diameter rockets any time soon), I am sure we could sell one too you. PM me later and we could work out details if you are still interested.