Loc LaserLoc 163, Mach 1 on Level 1 motors (with modifications)

The Rocketry Forum

Help Support The Rocketry Forum:

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
That looks a little like the bay I built for my 1.63 IQSY Tomahawk. I used a Quark. Plus yours looks neater than mine.
Very nice, I'm not done yet, so there still plenty to that will clutter it up. I also like to run screws through the bulkhead like you did. It keeps it gas tight. I used thumb nuts that make it easy to attach ematch wires by hand.
 

tOD

Sinking in the quicksand of HPR
TRF Supporter
Joined
Jul 31, 2018
Messages
501
Reaction score
223
Location
Pittsburgh, PA
Very nice, I'm not done yet, so there still plenty to that will clutter it up. I also like to run screws through the bulkhead like you did. It keeps it gas tight. I used thumb nuts that make it easy to attach ematch wires by hand.
The pull pin switch wasn't the best choice. I was going to use a magnetic switch, and had ordered them when the Tripoli/NAR rules on switches were revised. It would be nice if they were allowed once they finalize the rules.
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
The pull pin switch wasn't the best choice. I was going to use a magnetic switch, and had ordered them when the Tripoli/NAR rules on switches were revised.
I'm planning on a screw switch, relatively simple and straightforward. I'll be using a Proton, it's a little larger, but I want the accelerometer data.
 

tOD

Sinking in the quicksand of HPR
TRF Supporter
Joined
Jul 31, 2018
Messages
501
Reaction score
223
Location
Pittsburgh, PA
I'm planning on a screw switch, relatively simple and straightforward. I'll be using a Proton, it's a little larger, but I want the accelerometer data.
You're building quite a different animal than mine which putts along on 29 Hobbyline motors. I may get around to putting an H in it.
 

Handeman

Well-Known Member
TRF Supporter
Joined
Jan 18, 2009
Messages
7,613
Reaction score
211
Location
Stafford, VA
I don't know if this really makes a difference, but when it comes to fin flutter, IIRC a flat fin will flutter before a shaped fin because of the different thickness and stiffness in different places.

What I did on my 4" scratch build (75mm MMT) was tip to tip the fins with three layers. The first layer 1/2 as long as the fin length and 1/2 the width. The second layer 3/4 the length and 3/4 the width and the last covered the whole fin. It isn't a lot of shaping, but I thought it might be enough to make the fin survive a few more 0.x mach numbers for a few more second. YMMV
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
The first layer 1/2 as long as the fin length and 1/2 the width. The second layer 3/4 the length and 3/4 the width and the last covered the whole fin.
That makes sense, and seems like a good approach. Changing the stiffness across the spans makes some intuitive sense. I may do that, thanks for the tip.
 

Nytrunner

Pop lugs, not drugs
Joined
Oct 15, 2016
Messages
6,554
Reaction score
1,981
Location
Huntsville AL
Shaping/tapering also reduces the mass at the tip of the fin. (Imagine swinging your empty hand back and forth in the air, then hold a 1 or two pound weight in your hand and do the same thing. Greater inertia at the tip elements lead to greater stresses in your fin (and arm). Although the extra pound isn't "alot of weight" compared to the weight of your entire arm, you can feel the difference )
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
Shaping/tapering also reduces the mass at the tip of the fin. (Imagine swinging your empty hand back and forth in the air, then hold a 1 or two pound weight in your hand and do the same thing.
Is it relative stiffness to mass that matters? Is removing mass at the tips more or less equivalent to adding stiffness at the roots?
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
Three fins cut, and crenalations (castle thingys?) transferred. After a bit of filing, the fit is good. A quick test fit, and then on to shaping the fins and prepping for fiberglassing. There should be enough room at the base of the rocket for a wrap of aluminum tape for additional motor retention.

P5150447.JPG
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
Obligatory fillet shot. I like to use 30 minute epoxy with phenolic micro-balloons, smoothed with a gloved finger dipped in alcohol. It will take a bit of sanding, but it is a good start.

P5160452.JPGP5160453.JPG
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
After a careful aerodynamic analysis with some computational fluid dynamics, I determined that 13/16" dowel was the optimum size for sanding fillets. Actually, I had one in reach, and "TLR".

I took a break from sanding to weigh booster section. I wish I had weighed it before fillets, they feel heavy.

I can estimate it, though. If a 34" length of LOC 38mm tube weighs 4.13 oz, my 22.5" section should weigh about 2.7 oz. The three original LOC fins weigh 0.9 oz. So the original parts weighed 3.6 oz, my current booster plus alternate fins, plus glue, plus fillets weighs 4.1 oz. So roughly 0.5 oz fillets if the fins weigh the same, which is actually less than I thought.

P5170454.JPG
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
Finished sanding. I cut new pieces of 5 oz fiberglass cloth large enough for the new fins, and set aside the original pre-cut pieces from LOC. I'm not sure yet, I may do a second smaller layer of fiberglass. One side down, two more to go...

P5170455.JPGP5170456.JPG
 

C.O.B.H.C.

Well-Known Member
Joined
Jan 26, 2009
Messages
237
Reaction score
9
Location
The Peoples Republik of Kommiefornia
The kit fins get the job done, but it the shape does not really appeal to me. Deltas and clipped deltas are certainly functional (and have their advantages) but a secondary (primary?) goal is to exceed Mach 1 in style. I borrowed this shape from another rocket I really like, does anyone recognize it? They are slightly larger, and I'm shifting them forward a hair, so I expect this will be slightly slower, but looking good is important.

View attachment 416555

View attachment 416557

I cut the fins out of 1/8" ply, transferred the crenelations (??) with a razor saw, and cleaned up the cuts with a scroll saw and small file.

View attachment 416559

I like this much better!

View attachment 416560
GLR Mariah.
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
Fiberglassing is done, the third piece came out quite a bit better than the first. My estimation for the amount of resin needed was much closer to being correct, and I did a better job of removing excess and working it into the cloth evenly. There is little no pooling or air bubbles on this last section. The current booster weight is 4.9 oz, so fiberglassing added only 0.8 oz. That is quite a bit less than I thought it would be.

P5190457.JPG
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
Starting the filling / sanding / priming / sanding stages .....

P5200458.JPG
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
It looks like 18 oz will be a minimum weight. I still have some glue, primer paint, and miscellaneous hardware to add, and I'm over 17 oz.

The AV bay is nearly done, I made recovery attachment points from aluminum angle. I may have to do some testing to see if this is strong enough. The battery is framed out and totally captive, it can't move unless the wood crushes. It sits on the lower bulkhead. One section of 6-32 threaded rod runs through the center.

P5210460.JPG

P5210461.JPG

P5210462.JPG

P5210463.JPG
 

Mugs914

220, 221; whatever it takes...
Joined
Oct 1, 2012
Messages
1,077
Reaction score
572
Location
Temple TEXAS
Really nice av bay! I really like your recovery attachments. Hope they hold up to testing!
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
I've been waffling back and forth on a tower or not. As much as it would be the *right* way to do a mach 1+ rocket, I just don't want another long skinny thing to store and haul to the field with me. So rail guides it is. I ordered a pair of nice ones from Wildman, and installed them tonight. I cut off a pair of 4-40 machine screws to a depth so that it just goes through the LOC body tube, and drilled and tapped the holes for 4-40 threads. The rail guides are epoxied on, but the screws will add a bit of mechanical bite.

I filled in the screw head and gaps with epoxy, that will get smoothed down flat after it cures. I'm nearing the end of the filling / sanding / priming steps.

P5230464.JPG

Next, I need to make some decisions about motor retention and recovery attachment. Ideally, the motor would have positive retention and the shock cord would be inspect-able and replaceable. It is difficult to accomplish both in a minimum diameter rocket.

I'm leaning towards attaching the recovery harness direct to the motor, like Crazy Jim shows for Aerotech (here), or CTI (here). Another possibility is attaching the recovery harness to the 38-29mm motor adapter for 29mm flights, that would more easily accommodate some of the single use and DMS motors I might like to fly.

The other option would be to install a bulkhead in the booster and run a long loop of kevlar through it, so it can be inspected and replaced.
 

o1d_dude

'I battle gravity'
Joined
Jan 18, 2009
Messages
7,729
Reaction score
587
Location
Urff
I can’t find any BT60 coupler tubing in lengths longer than 4-5 inches. I’d like at least a 6” long coupler.

Where did you find yours?
 

HVArcas

Well-Known Member
Joined
Oct 25, 2016
Messages
232
Reaction score
80
laserloc been on my radar, maybe should order one right up..

Your milestones are probably beneath your current skill level. Worry less and push the button! :) seriously tho, i applaud your caution. most of those I work with are quick to turn from a minimal cert flight to some top-spec monstrosity on the next flight (sometimes at the same launch!)
 

HVArcas

Well-Known Member
Joined
Oct 25, 2016
Messages
232
Reaction score
80
I can’t find any BT60 coupler tubing in lengths longer than 4-5 inches. I’d like at least a 6” long coupler.

Where did you find yours?
i have no idea what BT60 means but Mach 1 uses whatever notation that is, and could probably get you a long coupler
 

o1d_dude

'I battle gravity'
Joined
Jan 18, 2009
Messages
7,729
Reaction score
587
Location
Urff
i have no idea what BT60 means but Mach 1 uses whatever notation that is, and could probably get you a long coupler
BT60 is the 1.63” tubing our LaserLOC 1.63 rockets are made from.

I’m trying to put an av bay in mine as you have done but can’t find any coupler tubing long enough (6-7”). LOC only lists 4” long couplers.
 

Mike Haberer

Well-Known Member
TRF Supporter
Joined
Jan 7, 2019
Messages
168
Reaction score
85
BT60 is the 1.63” tubing our LaserLOC 1.63 rockets are made from.

I’m trying to put an av bay in mine as you have done but can’t find any coupler tubing long enough (6-7”). LOC only lists 4” long couplers.
The rule of thumb is to have (roughly) one caliber (rocket diameter) on each side of the connection, so for a 1.63" diameter rocket, you'll likely not find a coupler longer than 4". I've also looked as I'm going to use couplers in my Super Big Bertha to strengthen the airframe to allow larger motors. They don't exist in cardboard. If you don't care about weight, you can use either a Blue Tube coupler (they come in 48" lengths) or fiberglass (8" from Apogee).
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
I can’t find any BT60 coupler tubing in lengths longer than 4-5 inches. I’d like at least a 6” long coupler.

Where did you find yours?
The 4" couplers from LOC were actually 5", which was a good thing, the Proton and battery would have fit within 4", but 5" gives it more room. How long is the one in your LOC kit?

Somebody somewhere has full length couplers, where did I see that....

Rocketarium has full length phenolic. But I think Mike is right:

They don't exist in cardboard.
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,972
Reaction score
897
laserloc been on my radar, maybe should order one right up..

Your milestones are probably beneath your current skill level. Worry less and push the button! :) seriously tho, i applaud your caution. most of those I work with are quick to turn from a minimal cert flight to some top-spec monstrosity on the next flight (sometimes at the same launch!)
Thanks! Yeah, there are so many things to do with Level 1 motors, I'm less interested in "leveling up" than I am in trying new things and seeing what I can do. For me, it is fun to pursue specific goals and try to optimize and learn along the way.
 

HVArcas

Well-Known Member
Joined
Oct 25, 2016
Messages
232
Reaction score
80
Thanks! Yeah, there are so many things to do with Level 1 motors, I'm less interested in "leveling up" than I am in trying new things and seeing what I can do. For me, it is fun to pursue specific goals and try to optimize and learn along the way.
I used to fly with a student who had jr L1, but I swear he had more skill and knowledge than the average L3. He was staging composites, inventing new recovery techniques, and had electronics out the wazoo. He said something about progressing to the point where he could do an L3 project, and i was like "man I would trust you with an O3400 right this minute if you had the cash and had built a rocket for it". It was truly awesome to watch his projects, doing more with small motors than most of us ever do with big ones.

I think lots of it comes down to attitude. The folks rushing for power are often not the ones who should be holding it, both physically and institutionally.
 
2
Top