There are piston guys in the club (JW, Warren M., Doug Gerrard, etc.), and those who don't use pistons because they can bind.

I'm a *huge* fan of pistons. Much depends on the airframe, but I have used glass airframes on something like my last 9,000 rockets 😆 If your nosecone ever shakes loose and your charge fires, if you don't have a piston you will have a sad ending to your flight, as the ejection charges will blast right by. A piston will get the laundry out 99.9% of the time.

At the end of the day, you must do what is comfortable for you -- this applies to one altimeter or two, EX vs. certified, hybrid vs. AP, drogue vs. drougeless, phenolic vs. glass, plywood vs. G10, conical vs. ogive, carbon vs. glass, Aerotech vs. AMW, snap rings vs. threaded closures, West Systems vs. Aeropoxy, etc. etc. etc. For me, pistons make sense. I'd never use them in Quantum tubing, though -- too much variablility in the expansion of the materials.

I've flown pistons perhaps 200 times, and I've never had them bind. Much of that is because I fly glass, which does not get dinged, which in turn could cause jamming. I also go at least one caliber for my piston length. I can probably count on one hand the number of times when I flew without a piston for the main, and that is when I flew something like a 24mm project which was paper. Bottom line, "dance with who brung ya". In my case, that is pistons. I definitely understand why others would do otherwise, though. And if that is what makes you comfortable, then you should absolutely go that route.

J

The method you guys are referring to is what most call zipperless. Its not the
"norm" as it may think. I don't believe there is a normal way to do alot of things in this hobby. But a lot of preferred ways that people do them.

I like to do the zipperless style deployment because it separates normally the 2 biggest sections.Which also causes the highest drag as the rocket falls back to earth. In doing so it helps slow down the rocket. In fact so much that you can just stretch it out on only a harness making it a drogue-less recovery. Trying to do a drogue-less recovery by just popping the nose off doesn't normally work well as the rocket is still in one main piece and can still come in ballistic. Even with a chute you will then have a large airframe section hanging below and deployment in that state can cause tangle issues with the airframe. Its also easy for a main to blow off a much smaller section then it is a larger section and have it deploy.

So like others you see at NCR that fly DD I to chose to do the zipperless design. Apogee booster and main airframe separate and then stretch out and then the main gets pushed out with the nose cone ejection.

Conway

I haven't done anything but zipperless in 3 years...

Warren

So, correct me if my thinking is wrong. I dont think they specify in the instructions, or at least I didnt see it. Drogue chute in the top at the nose cone and main at the bottom. My thinking is the fins will help keep the rocket flat with the drogue out and eject the main off to the side. Less likly to get tangled ?? Other wise the nose would be hanging down and the main would eject down. Anyone???

Scott e

One issue going with the drogue up top is that if it strips or if it stays inside the airframe (not a problem if you use PISTONS 🙂 ) then you may come in pretty hot - more or less ballistic.

I always break the midsection at apogee (I almost never use a drogue) and then have the main up top.

As an aside, if I do use a drogue, I use a streamer -- even on big honkin' rockets. I have probably used a drogue chute ~3 times, a streamer ~20 times, and neither perhaps 150 times. I actually keep track of this minutia, I'll have to check my logs to see for sure. Really heavy rockets probably benefit from a drogue or some sort. I tend to use really long shock cords that are coiled very tight. So far, so good. I'm going to try a TRA "M" altitude attempt in '08, and it will *not* have a drogue chute or streamer...

JW

A full-sized Nike-Black Brant comes in hot from 900 miles down to 25000' AGL before popping the drogue chute which then pulls the 48' main out directly. The chute pops at Mach 2+. How's that for a justification of no apogee drogue? With the right chute and chute attachment, you can pretty much do nothing other than break the aerodynamic shape of your bird and let it fall down to a reasonable altitude before blowing the main. Personally, I never pop the main below 1000'.

Warren

A full-sized Nike-Black Brant comes in hot from 900 miles down to 25000' AGL before popping the drogue chute which then pulls the 48' main out directly. The chute pops at Mach 2+. How's that for a justification of no apogee drogue? With the right chute and chute attachment, you can pretty much do nothing other than break the aerodynamic shape of your bird and let it fall down to a reasonable altitude before blowing the main. Personally, I never pop the main below 1000'.

Warren

But then again we dont make professional space vehicles. I dont think the government worries either if they will get their cert or not. And for the record, Most if not all vehicles at a high power launch that come in a pretty fair amount of their altitude hot, dont live. They shred a chute and the rocket, or just the chute, at the least a zipper. all things that disqualify a cert attempt. for me it depends on the size of the project, the wind and how far I feel like walking as to when I pop my main. Bigger stuff like my L3 is 1500. Smaller stuff is 800ft.

ok
so the main will go in the nose.
One thing to mention in this rocket, it more like pops the back off (or fin can) than breaks in half. (not much halving there) I did find a place in the instructions that show the drogue in the back.

Scott e

Scott, not a PML guy here. They make great rockets though. I just went a different route. I'm one of those main-out-the-nose guys. But it's so great to have a new member so excited and asking questions. You'll never find a club more ready to help. Sorry I CAN'T help on this one, but it's good to have you aboard!

Well

The forecast for Satuday is HIGHS IN THE 30s! (hope it changes)

Um--do we worry about Um--O-ring failures? 😯
Does the club have de-icing equipment or is the flyer responsable for his own heating system? 😉

Scott e

Well

The forecast for Satuday is HIGHS IN THE 30s! (hope it changes)

Um--do we worry about Um--O-ring failures? 😯
Does the club have de-icing equipment or is the flyer responsable for his own heating system? 😉

Scott e

No you dont have to worry about oring failure. You wont need de-icing either. Yes you are responsible for your own heat.

And no Conway doesnt come out and fly at 30 degrees. He will go to an event where its 120 degrees but not the other direction 😀

Then how am i gonna get my cookie?

Then how am i gonna get my cookie?

Meeting? 😉

Actually if its like today I can hack it.

---racing to finish and maybe even have paint by saturday! 🙂

Scott, was your meeting with Ken informative? Paint, man, paint! Are you going to attempt your L2 on Saturday? Can't be there, gonna be warm and watching Tennessee beat LSU. Yeah, right. 😉

If they are flying Ill be there!
I may be sitting in the car but Ill be there!
I actually use to work outside in the winter many many moons ago.
So as long as the wind aint blowin it wont be bad!!

And yes Kens Carbon Diem is beautiful.
I was impessed too, with the muscles in his arms, from all that sanding! 😉

I really like his double altimiter-ejection thing-a-ma-jig.
Ill have to build one. Would make me feel better than PMLs single CPR3000. The Quantum Leap is starting to turn into a pretty nice rocket.
Id hate to crunch it before I got to try both stages.

I ordered some carbon sleaving from the place who is having that sale.

And finally after 7 -8 weeks got this Thor Rocket from BDS/Just Rockets.
Does any body have any experiance with this guy? Was he just having an off, couple of months???
I was originally gona Certify 1 and 2 with it but it didnt come till yesterday. Glad I didnt wait for it. I ordered it the monday after Octoberfest!
Anyway I might sleave its tubes for practice, it might be the last kit I build.
Every thing else will be probably scratch built.
Got to go sanding myself now.

Scott e