Quantcast

Long Distance Certification(s)

The Rocketry Forum

Help Support The Rocketry Forum:

joepolicy

Well-Known Member
Joined
May 23, 2004
Messages
139
Reaction score
0
First off, feel free to tell me if I am crazy....

I accepted an invitation to the Freedom launch, 4-5 September in Orangeburg. I figured while I was there, I may as well attempt my L1 and possibly my L2 since it is a 8,400 mile round trip from Germany and I want to make the most out of it.

I am restricted for sizes of packages I can mail to the states, so I am building a PML Ariel and PML Tethys, both have the kwik switch mmt's for 54/38/29mm motors. I can easily mail the completed rockets, but they will just be under the USPS mail size restrictions, so I cannot build/mail anything bigger. I will not have time for any building since I arrive on 3 September and the launch starts the next day.

I am planning on doing my L1 with the Tethys on an H128W, sims to about 936 feet, no problem there. The L2 has me concerned since the J350 motor I want to use will send both rockets to over 5000 feet according to RockSim.

I could really use a recommendation on what would be the best way to recover either rocket from a J350 flight. The Ariel does have a payload bay, but I have not worked with altimeters, drogue chutes, etc. before, so I am trying to do the HPR fast study thing. Tethys has PML stock 48" chute and Ariel has PML stock 36" chute.

I am concerned that if I use a standard ejection charge, I will not get my rocket back as it floats out of site 5000+ feet downrange. I assume I will need some sort of electronics arrangement, the simpler, the better. I am short on time, but I can still get parts if needed. Would love to hear some ideas on what I can do to bring the rocket safely (and visibly) back home.

My other concern is the velocity which sims at over 1,000fps for both rockets. The Tethys will have internal epoxy fillets (after heavy roughing up of course) with 6oz glass and then PML foam will be added to the fin can. The external fillets will be made using West Systems 105/205 with 404 filler material (I also have 405 and 406 filler if one is better then the other). I will not be externally glassing the Quantum Tube since that is not recommended. Will the G10 fins/QT hold up under the launch velocities if I build strong internally?

Appreciate any help anyone can provide. I am +7 hours from central time, so please excuse me if I do not respond immediately to questions.

Thanks!
 

Justin Horne

Well-Known Member
Joined
Jun 23, 2004
Messages
425
Reaction score
0
Well, we've got a tethys with a 54 inch chute. Launches it on an I284 and it was only a few hundred yards away in 10 mph wind.. We did angle it into the wind though...

As for the quantum, PML only recommends 85% of mach... Since i havent flown QT that fast, I can't tell you..

By the way.. Signs you've been doing rocketry to much:
"...since it is a 8,400 mile round trip from Germany...."
indeed...:D
 

xenon

Well-Known Member
Joined
Jan 25, 2009
Messages
698
Reaction score
0
I would not recomend pushing 1000fps with the Quantum tube. PML FAQ says it should not be used in the transonic to supersonic range.
That should be the answer there unless you can get a longer burn motor and keep it slower.
The long burn J90 would be awsome:D but it would be tough to get a motor.
OR, you could use an SRS J144 hybrid, of course that would require electronics.

Good luck on the L1
 

karatekicker271

Well-Known Member
Joined
Jan 25, 2004
Messages
943
Reaction score
0
I hope you can do it..... because I will be witnessing it:D :D :D :) I will get to see it.
 

Rocketman248

Well-Known Member
Joined
Jan 30, 2009
Messages
2,380
Reaction score
8
You could use the Pro38 J285. It's just a baby J. It would probably handle that.
 

Rocketjunkie

Addicted to APCP
Joined
Jan 19, 2009
Messages
4,132
Reaction score
357
A J285 is the smallest J motor available and will help keep the altitude down. If the clouds don't build late in the day, the last 2 hours before sunset are usually calm on the site. The second best time to fly is first thing in the morning when the range opens. If the winds are under 5 mph (about 8 Km/hr), you can recover a 5000 foot flight on the field consistently.
Rocksim tends to be optimistic on the altitude.

There will be motor vendors on the field for the Freedom launch.
 

joepolicy

Well-Known Member
Joined
May 23, 2004
Messages
139
Reaction score
0
Originally posted by Rocketjunkie
There will be motor vendors on the field for the Freedom launch.
Is there a list of vendors who will be attending posted anywhere? I would like to contact them beforehand to ensure availability of motors I might need.

I did the Sim with the J300, looks better on the velocity. Does anyone have the .eng file for the J285?

Thanks for the help so far, there may be hope!
 

HeadHunter

Well-Known Member
Joined
Dec 10, 2010
Messages
248
Reaction score
0
here is the eng files for the newer pro38 stuff, it is a little different than the old stuff. I was going to use this last weekend for my level 2 but the test tripped me up.:(
 

Oliver Arend

Well-Known Member
Joined
Aug 14, 2001
Messages
106
Reaction score
0
Are you German or just stationed there?

Oliver
being in Stuttgart
 

joepolicy

Well-Known Member
Joined
May 23, 2004
Messages
139
Reaction score
0
If I add 2 lb of weight to the fin can (between the Kwik Switch 38mm MMT and the "permanent" 54mm MMT) and another 2 lb to the nose cone, that really brings down the velocity to an acceptable level. The RockSim numbers look much better and I can keep the CG/CP in line. Any pros or cons to doing this? The added weight would be epoxied into place.

Thanks,
 

llobdelljr

Active Member
Joined
Jun 7, 2009
Messages
28
Reaction score
1
I did my L2 with a LOC EZI-65 and a J350. I was told the fins tend to rip off these at high speed so I ran RockSim adding more weight each time till I got the max velocity down to about 750 fps. From the RockSim figures I determined I needed to add 2-1/2 pounds so I went to the hardware store and bought 3 bolts and nuts that together weighed about 2-1/2 pounds (we weighed them on their scale). DO NOT tell the hardware man what you are going to do with them - he will probably give you a really strange look! :)
The EZI-65 coupler is 6" long so I bought 7" long bolts. I drilled 3 holes through two bulkhead plates. I put one plate on each end of the coupler (no glue), put the 3 bolts through the 3 holes, and tightened them. The result was a heavy coupler with bulkhead plates at each end and 3 bolts going through lengthwise. When I put this assembly in the rocket, the added weight slowed the rocket down enough to use a J350.
The advantage of this design is that the weight is not permanent.
If I want to use smaller motors I just remove the bolts and the bulkhead plates from the coupler and the rocket is instantly 2-1/2 pounds lighter.
Hope this helps.
Larry Lobdell Jr.
 

lalligood

Well-Known Member
Joined
Jan 21, 2009
Messages
1,975
Reaction score
0
Originally posted by joepolicy
If I add 2 lb of weight to the fin can (between the Kwik Switch 38mm MMT and the "permanent" 54mm MMT) and another 2 lb to the nose cone, that really brings down the velocity to an acceptable level. The RockSim numbers look much better and I can keep the CG/CP in line. Any pros or cons to doing this? The added weight would be epoxied into place.

Thanks,
Don't forget to add a MUCH larger chute! :eek:

And I would either make the additional weight removable or only add the additional weight in one rocket. Otherwise, you're going to have an underpowered L1 flight...

HTH,
 

Rocketjunkie

Addicted to APCP
Joined
Jan 19, 2009
Messages
4,132
Reaction score
357
Originally posted by joepolicy
Is there a list of vendors who will be attending posted anywhere?
Rocket Science (Larry Smith)
Performance Hobbies (Ken Allen)
Possibly New Horizons Hobbies from Florida.
 

Rocketjunkie

Addicted to APCP
Joined
Jan 19, 2009
Messages
4,132
Reaction score
357
Originally posted by joepolicy
Is there a list of vendors who will be attending posted anywhere?
Rocket Science (Larry Smith)
Performance Hobbies (Ken Allen)
Possibly New Horizons Hobbies from Florida.
 
Top