Quantcast

L1 cert motor options

The Rocketry Forum

Help Support The Rocketry Forum:

shinbone

Well-Known Member
Joined
Mar 30, 2004
Messages
104
Reaction score
0
Aside from the obvious cost difference, I am inquiring of the educated and helpful assembly of TRF rocket scientists about the pros and cons of using SU vs. RMS for a Level 1 certification flight.
Please correct me if I'm wrong, but I see a negative on each side:
-- If I go RMS, I have the additional concern of doing a proper assembly at the field as opposed to just shoving an SU in the business end and letting her go, saving RMS for another day.
-- The SU option, however, seems to present a problem with motor availability. As we all have, I've been waiting for AT to get back up to full production. Seems to me there is very little out there in SU "H" motors.
What say ye, gentlemen and ladies? I'd like to make this happen late this summer.
 

lalligood

Well-Known Member
Joined
Jan 21, 2009
Messages
1,975
Reaction score
0
Go Pro38. The 2-grain H153 is the ideal Level 1 cert motor. That's what I used with my PML Phobos...

There are no availability issues with Pro38 & the motors themselves offer easier setup at the field than RMS but are more affordable than SU. (The casings can only be used with Pro38 reloads though.)

Pretty much all you have to do is take off the forward closure (which contains the delay grain & ejection charge, adjust the delay with the ProDAT tool, pop it back into place, & then screw the reload into the casing. The ignitor included with the motor is an electric match & I've never seen one fail to ignite the first time.

Just the $0.02 from a very happy Pro38 user... :D
 

Chilly

Well-Known Member
Joined
Feb 2, 2009
Messages
1,165
Reaction score
1
I'll have to go back and check my TRA guidelines, but doesn't certification include "assembling the motor" or am I just confused?

I'd have gone Pro38 if I'd had anything with a 38mm mount. But I was dying to build the Mini-BBX so went with 29mm for my cert.

That's actually a pretty economical way to go. A Dr. Rocket 180-240 casing set is less than $70 and most reloads average between $12 to $15. The most expensive reload for that Isp is about 22 bucks. So you're not spending much more than you would for a G64. Building AT reloads is really not that complicated. Cleaning them is a bummer, though.
 

shinbone

Well-Known Member
Joined
Mar 30, 2004
Messages
104
Reaction score
0
" ...adjust the delay with the ProDAT tool ..."

How does that work? And what's the best way to determine the optimum delay, besides Rocsim?
 

shinbone

Well-Known Member
Joined
Mar 30, 2004
Messages
104
Reaction score
0
And to Chilly:
The NAR certification rules say that "Single use, reloadable, or hybrid technology motors are permitted." If you choose reloadable, you have to assemble it in front of your witness.
 

shinbone

Well-Known Member
Joined
Mar 30, 2004
Messages
104
Reaction score
0
And for lalligood:
Can I assume the Pro38 comes with fore and aft closures, or are they purchased separately? I know you need to buy the delay tool separately.
 

Johnnie

Well-Known Member
Joined
Dec 31, 2002
Messages
4,289
Reaction score
0
All though the Aerotech L1 applicable motors have more parts to assemble, they are easier to assemble than an Estes Alpha, and cheaper than a PRO38 H!!!!!

H128 all the way...

Borrow a casing from a local flier.

Our club has a set of loaner reload casings for all L1 and L2, to include HyperTEK tanks for L1 and L2 as well. We offer these to qualified cert individuals as well as anyone just needing that casing...you loose it, or blow it up, you buy it.

I likes a good L1 I do
 

Ryan S.

Well-Known Member
Joined
Mar 24, 2003
Messages
3,550
Reaction score
0
the proDat drills away some delay element so there is less space in between the ejection charge and the burning surface resulting in a shorter delay.

For a Pro38 motor you just but the case. The forward closure is machined into the case and the aft screws in so you have no aft closure because the load already has one worked into it.
 

lalligood

Well-Known Member
Joined
Jan 21, 2009
Messages
1,975
Reaction score
0
Originally posted by shinbone
" ...adjust the delay with the ProDAT tool ..."

How does that work? And what's the best way to determine the optimum delay, besides Rocsim?
You determine the delay like you would any other flight...(yeah, for most folks, it's RockSim to the resuce!)

Specifically with Pro38, the delay grain comes with a delay of 13-16 seconds (depending on the size of the reload). The H153 comes with a 13 sec max delay. From there, the ProDAT is a drill bit with a notched handle (hard to describe but when you see it, you'll completely understand how to use it!) allowing you to subtract 3, 5, 7, or 9 seconds from the delay by coring out the grain with the tool. For example, I flew my Phobos with a 10 sec delay, so I subtracted 3 seconds from the delay.

As far as the closures go, they are built into the reload (perhaps explaining why the Pro38 reloads are more expensive than comparable AeroTechs...?) In other words, the delay/ejection cap IS the forward closure held in place by a lip on the forward end of the casing. The rear closure/nozzle is all one piece with the grain(s). Almost sounds like a SU motor, doesn't it?!?

Despite the higher cost per flight, Pro38 gives you great flexibility with setting the delay time. Another knock on Pro38 is that you only have 2 propellant choices--classic (compare to AT's White Lightning) & Smokey Sam (like AT's Black Jack). But if you want easy & adjustable, definitely take look-see :)

HTH,
 

Donaldsrockets

Well-Known Member
Joined
Jan 18, 2009
Messages
3,518
Reaction score
1
Location
Fort Myers, FL
I would personally reccommend any of the Aerotech 29/180 reloads with the exception of the G75J. These reloads cost about $14.00 each. Pretty cheap for an H motor. Heck, some G motors cost more than that!!!

I think the H128W and H165R are great L1 cert motors.
 

edwardw

Well-Known Member
Joined
Jan 10, 2004
Messages
2,116
Reaction score
0
I went the Pro38 route for my L1/L2 certs. Couldn't be happier. Easy to adjust, cleanup is a breeze ( just take out the spent reload assembly). Our club rents Pro38 hardware per flight, so I rented the hardware then bought the reloads. For me it was easier to do that then buy or borrow an AT casing. Also, Pro38's light very fast cause of a pyrodex like pellet at the forward end. For me, I liked not having to assemble something in the field with all the stress of a cert flight. Buy the motor, screw together and fly.

Edward
 

loopy

Well-Known Member
Joined
Dec 13, 2009
Messages
4,570
Reaction score
1
AT's are really not that difficult to build. I've never done an HPR load, just the MPR loads, but I've watched the HPR loads being built, and it's all the same. It takes about three minutes. If you go this route, I would probably do a few MPR loads first, just to get it under your fingers.

I'm hoping to get into NAR this summer, and launch my Small Endeavour on an H165 for my cert.

Whatever you decide, good luck!

I think from this thread, you can kick the SU idea...lol. By the way - I think another problem with SU is that I don't think SU HPR motors have thrust rings, so you'd have to build up a masking tape thrust ring. Not a big deal, but I don't think I'd want to be waiting for my cert flight to launch, wondering if the motor is going to go shooting up through the rocket if the tape doesn't hold.

Loopy
 

BlueNinja

Well-Known Member
Joined
Jan 18, 2009
Messages
2,690
Reaction score
1
Yea, the AT reloads don't take much more time than the Pro 38s but are REALLY hard to clean on the field. They are also cheaper, a H128 is $12.50.
 

shinbone

Well-Known Member
Joined
Mar 30, 2004
Messages
104
Reaction score
0
Lots of great info here, guys. Thanks a lot.
I've already dropped the SU idea and just need to do a little more research on the AT/Pro issues.
Guys like you make this a great forum!
Wish me luck. The Intruder flies in August.
 

loopy

Well-Known Member
Joined
Dec 13, 2009
Messages
4,570
Reaction score
1
I don't think they are that hard to clean at all. As soon as it's cooled off a little, I just take off the closures, dump the contents, and it's still soft enough that I can wipe it out with a baby wipe and be pretty much set.
 

jetra2

Well-Known Member
Joined
Jan 25, 2009
Messages
2,792
Reaction score
2
I have found that a pretty easy way to clean out the threading and smaller areas of the reload casings is to use a toothpick. The round wooden ones will get right in the groove and as you turn the casing around the toothpick, you'll get all the gunk out of the threads, then you can just take a baby wipe to the interior of the case and the other areas.

Jason
 

Donaldsrockets

Well-Known Member
Joined
Jan 18, 2009
Messages
3,518
Reaction score
1
Location
Fort Myers, FL
Loopy

You'll like that combo. I just flew my Small Endeavour on an H165R recently.

Beautiful, beautiful flight, nice bright red flame off the pad and a rather quick straight shot up to about 2,000 feet.

Good luck
 

Stymye

Well-Known Member
Joined
Jan 21, 2009
Messages
7,568
Reaction score
4
yea... the aerotech H reload is a good price
too bad the aerotech 29/180 casing is about $50-60 !!!

the pro 38 2 grain case is only around $32
couple that with the ease of use and it's not such a bad deal to go with pro38 for a cert flight
 

firemanup

Well-Known Member
Joined
May 2, 2002
Messages
1,305
Reaction score
79
The AT 29/180-240 set is only about 60 bucks.. that's two casings and one set of forward and aft closures... heck think mine even came with the seal disk too...

Magnum lists the set for $63.95 right now on his webpage...

So really when getting two casings for 64 bucks is about the same as getting one Pro38 casing for 32 bucks.... to me the casings aren't that much more...

I like the Pro 38's also but I do feel they're a bit more expensive
 

Johnnie

Well-Known Member
Joined
Dec 31, 2002
Messages
4,289
Reaction score
0
My how times of changed...

when I certified L1 in 1998, one of the many perks was assembling your 1st Highpower reload. That was as much fun as the flight. Now most everyone says just give it a twist and go (PRO38).

The next best part was that silly grin on your face as you proudly cleaned your casing thinking about what you have just achieved.

Personally I would rather save $10 bucks a flight to install the (3) o-rings, liner tube (w/ grease), fuel grains, seal discs/fiber washers, delay tube and delay grain, and give a double twist. Seemed to me it was a big part of the high power experience.

I cannot knock PRO38's as I have never flown or assembled one. Watching PRO38's ignite quickly and burn is nice...but Blue Thunder...White Lightning...Blackjack...and the mighty Redline...that is four nicely priced reloads that are hard to beat.

Incidently, an H128 White Lightning reload in 1998 was $9.50. AHHH the good ole days. :p ...remembering in a daydream...
 

edwardw

Well-Known Member
Joined
Jan 10, 2004
Messages
2,116
Reaction score
0
I have to agree with Johnnie, assembling a motor is an experience to behold. With my *sweet tooth*, I have been doing that quite a bit lately. And it is also great to teach someone how to assemble a reload - and watch how the feel when their rocket went up and came down on the motor they put together. The only feeling that beats that is when it is your own motor you made and it actually flew :)

Edward
 

Donaldsrockets

Well-Known Member
Joined
Jan 18, 2009
Messages
3,518
Reaction score
1
Location
Fort Myers, FL
I happen to like assembling AT motors. I used an H128W for my L1 and I have to admit, it felt neat assembling the largest motor that I had ever flown other than the wind trying to blow the parts everywhere.

You could probably imagine my excitement when I loaded up my first I motor, an AT I161W:D

I will admit that the cleanup can be a pain in the a$$ sometimes but I think the cheaper price of the reloads is worth it.

I have only flown one Pro38 motor which was a 1 grain G69 and I sold my case on ROL not that long ago because I really did not want to pay the $20 for the reloads. I had gotten the casing and reload during Cesaroni's "back to school" special that was going on last year:rolleyes:

Just my 2 cents;)
 

Stymye

Well-Known Member
Joined
Jan 21, 2009
Messages
7,568
Reaction score
4
I enjoy building reloads too,and I own both types
I was refering more to a cert flight

I've seen a number of certs die over a poorly assembled aerotch
reload
I personally have not seen this happen with a pro38(so far)
the purpose of L1 is to build , fly,and recover a rocket
regardless of the motor used
thats my reasoning behind suggesting to the original poster
a pro 38 for his L1

plus
If the reload fails you are not only out of a reload but probably a rocket too ...starting to get expensive yet?

it's good insurance for a cert flight in my opinion
but ultimately up to the individual ofcourse
 

gerbs4me

Well-Known Member
Joined
Sep 21, 2009
Messages
3,102
Reaction score
3
Location
Iowa
Go with the Pro38 I212 Smokey sam:D
you won't be disappointed:)
 

Thrasher

Well-Known Member
Joined
Apr 25, 2004
Messages
624
Reaction score
2
I'm probably not the one to listen to because I used a 38/600 I195J for my Level one cert.

AT reloads are easy after the first one. They get easier each time you do it. Cleaning is no problem, I use my gun cleaning kit on the casings. It takes about a minute.
 

Silverleaf

Well-Known Member
Joined
Feb 22, 2003
Messages
1,124
Reaction score
0
Just wanted to say thanks to everyone for posting replies here. 8)

Though I'm no where close to try L1, I've been debating the best way to build the Astrobee D, and I might just try doing research on the largest MMT available, then use an adapter for my H power L1 attempt when the time arrives.

I've been searching the forum and found a few threads on beefing up the Astrobee, so hearing the voice of experience here on Pro-38 (I know nothing about these motors) and the RMS AT does give me pause.

Tough choices..
 

lalligood

Well-Known Member
Joined
Jan 21, 2009
Messages
1,975
Reaction score
0
One thing that always seems to get lost in translation of these "what motor should I use to cert with?" threads is that it's not Pro38 vs. AeroTech. That simply is not the case at all. If your rocket has a 38mm MMT, YOU CAN USE BOTH. The certification process is to safely demostrate that you are capable of building a rocket that can withstand all of the related stresses of launching & recovering when using an H or I class motor. There are no "style points" earned for certification. Certifications make me nervous (even though I had done "shakedown" flights on smaller motors with both my L1 & L2 rockets). I have a personal preference for Pro38 motors because I have found they are easier to prep & ignite. Your mileage may vary. (BTW, I certed L1 & L2 both times on my first attempts... I attribute it to simplicity & careful preparation.) However, the more opportunities for potential failure that can be eliminated or at least reduced, translates directly into a better chance of your success with the certification flight. After that, GO WILD! You earned it :D
 
Top