Greetings! New member buying LOC IV with lots of questions!

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Curtis Enlow

Well-Known Member
Joined
Mar 24, 2019
Messages
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Location
Western Washington
Greetings!

I am a new member here, so some personal background: I grew up as a 60's 'space kid' and used to fly rockets as a kid (in my day 'D' motors were HUGE, as well as the only thing available here at that time), and then, again, as an adult with my son. I have pretty extensive tech experience - I built airliners for 15-years, worked in aviation ground support and radial engine overhaul shops. I am restoring a wooden sailboat (I know a lot about epoxy! LOL) I fly R/C planes and work in the audio/video industry as a sound person and camera op, so electronics, software, etc., is something in my skill set. I have also watched more YouTube videos on rocket construction, etc., than any normal, responsible adult should...

I am very close to pulling the trigger on a LOC IV as a mid-power flyer to get back in to the hobby. I plan on adding an e-bay and body extension to fly as a high-power, dual-deploy L1 Cert machine at the high-power site 4 hours from my home in Western Washington later this Spring.

As of now, this is the hardware I am considering for the LOC IV (this includes HP hardware that will not necessarily fly in the MP configuration):
  1. Missile Works RRC3 Altimeter
  2. Aerotech RMS 38mm Reload Adapter System
  3. Aerotech 38/360 RMS case
  4. 9/16" tubular Nylon shock cord with 200lb BB swivel hardware
  5. 4" X 12" body tube extension with an 8" coupler to make into my e-bay.
  6. RMS Delay drilling tool
  7. 38mm Aeropack motor retainer
I plan on vacuum bagging a layer of fine glass & epoxy onto the fins, with an additional tapered form layer to produce asymmetric airfoil fins, as I know the fins are a weak spot on the IV, and I want them tougher for desert landings as well as high-power flight.

I guess my first question would be, is the 360 case long enough to fly the full range of H-I motors after I get my L1? Also, do I need forward and aft closures for the 38/360 RMS case if I am using the RMS Reload Adapter kit? (I'm a little sticker-shocked at the prices of relatively simple fittings and don't want to buy them if I don't need them).

Also, will a single-use 38mm 'G' motors simply fit the IV's 38mm MMT with no additional hardware other than a motor retainer?

Also, is there a problem with using aluminum hardware, U-bolts, etc., where possible instead of steel? An aluminum 1/4" U-bolt is still pretty indestructible for small HP rockets and the difference in weight if you use several in a build is considerable...

I am concerned about the 1500g weight restriction a my local mid-power restricted field, but am also concerned about recovery, especially as our local field is a large athletic field complex, but still surrounded by roads, trees, other people, etc., within drifting distance of a main/apogee release on a windy day. In anyone's experience would a dual-deploy set up, as I have outlined above (with special care taken to minimize epoxy with chopped glass strengtheners, micro-balloons in aerodynamic fillets, etc.) on a LOC IV, still be too heavy to meet the maximum weight standards? I considered the ChuteRelease system, but the price...yikes...

I know this is a lot, and thanks to those who are still reading! Any thoughtful responses and experiences regarding my parts selections of planning will be appreciated.

Warm regards,

Curtis
 
Welcome Curtis! Glad to hear you're back in the hobby.

I can't answer all your questions but can give a little info. The 38 mm 360 case will be limited to around 360 Ns of impulse. I'm not aware of single-use 38mm G motors but they may be out there.

No specific problem with aluminum hardware at the impulse levels you're looking at.

Apogee provides instruction on making your own chute release system at https://www.apogeerockets.com/education/downloads/Newsletter277.pdf

Best regards -- Terry
 
Thanks, Terry!

I appreciate your response.

Ahhh, I see looking at the Aerotech RMS reload kit cross reference document that the 'I' motors go up to a 600-size case. I don't know that the reload adapter kit supplies enough spacers to use the smaller motors in that long of a case, however, plus I am concerned about excessive & unneeded weight for mid-power operation. I imagine it will be a while before I work up to the bigger 'I' motors and will probably want to go to phenolic or fiberglass(ed) bodies for that...? So a 360 case will probably be fine, for now.

Thanks, again,

C
 
The Loc rockets are all great choices. I suggest you hold off on the fiberglass and other extreme mods to start, but if you're inspired to try, don't let anyone stop you.

I put together a video showing the mods I think are good for the LOC IV:
jcrocket.com/certify-level-1.shtml

John, I love your rocket videos, and have watched them all (a few more than once!). (I recently commented regarding your Nike fins vacuum bagging video and talked lav mics. I am chasing down a Foodsaver on CL as we speak).

I plan on starting with, essentially, the base I kit for the mid-power flights but will retain the option for dual-deploy/e-bay/extended body for a high-power L1 attempt later this Spring.

Curtis
 
I recently built an Apogee Zephyr with the same plan to use it as a mid power as well as a L1 ship. It quickly found that it is near impossible to add a 29mm motor adapter and an Aeropack retainer and still stay under the 1500 gram weight limit for mid power. Once I decided that 1500 wasn't going to happen, I beefed it up and wound up at 1608 grams without motor. It went about 650' on a G80 for a test flight and then about 1340' on a Aerotech H135 Single Use for my L1 certifications flight. I'm building a new center section now to convert it to dual deployment for a L2 attempt on a J270. I'm probably going to build something with 54mm or 2.6" airframe as a mid-power "frequent flyer". I think it will be easy to stay under 1500 grams with the smaller airframe while still building it tough enough for a "I" or small "J" motor.
 
I am very close to pulling the trigger on a LOC IV as a mid-power flyer to get back in to the hobby. I plan on adding an e-bay and body extension to fly as a high-power, dual-deploy L1 Cert machine at the high-power site 4 hours from my home in Western Washington later this Spring.
Welcome back to the hobby. I built a LOC IV as my return into rocketry since the long break from my childhood. The LOC IV is a fantastic looking rocket.
I plan on vacuum bagging a layer of fine glass & epoxy onto the fins, with an additional tapered form layer to produce asymmetric airfoil fins, as I know the fins are a weak spot on the IV, and I want them tougher for desert landings as well as high-power flight.
I broke fins and repaired them on two occasions during many flights. I did fiberglass the fins during the second repair, and never had another broken fin again. However I shortly treed it in the middle of a swamp in FITS (Mansfield, WA) not long after. :( But I think its worthwhile for tough landings, but overkill for flight stresses of an H or I motor. Others might argue for a larger parachute, but not when you have to chase it in the wind, more so when its being dragged across the ground.
I guess my first question would be, is the 360 case long enough to fly the full range of H-I motors after I get my L1? Also, do I need forward and aft closures for the 38/360 RMS case if I am using the RMS Reload Adapter kit?
Yes, you will need the closures. If you go to Aerotech's webpage, on the products tab there is a Motor Matrix that shows the loads that fit the case. Go down a size (or two) if you put in the spacer (or two). If you look at the Resourses tab, you can find instructions for each motor, and it will tell you all the hardware you need (although modified appropriately if you use the RAS). You can also look at CTI or Loki. For G motors in a LOC IV, I always loved the Loki G69 Spitfire (Loki's sparky).

Also, will a single-use 38mm 'G' motors simply fit the IV's 38mm MMT with no additional hardware other than a motor retainer?
I don't believe there are any 38mm sigle use G motors. Plenty of 29mm, but you'll need an adapter. LOC makes an inexpensive 29mm to 38mm adapter that works. More expensive, Aeropack has an elegant and simple to use adapter if you have an Aeropack retainer.
I am concerned about the 1500g weight restriction a my local mid-power restricted field, but am also concerned about recovery, especially as our local field is a large athletic field complex, but still surrounded by roads, trees, other people, etc., within drifting distance of a main/apogee release on a windy day. In anyone's experience would a dual-deploy set up, as I have outlined above (with special care taken to minimize epoxy with chopped glass strengtheners, micro-balloons in aerodynamic fillets, etc.) on a LOC IV, still be too heavy to meet the maximum weight standards? I considered the ChuteRelease system, but the price...yikes...
My opinion: Yes, I think if you add the tube extension with dual deploy hardware, you're very likely to go over 1500g. Otherwise, its its original configuration, its quite doable to stay under 1500g if you don't overdo the epoxy and glassing. Again, my opinion, the Chute Release is a bit pricey, but it's very appropriate for flying the LOC IV with an H or I motor, or even a G.

I'd recommend keeping your LOC IV simple, then experiment with dual deploy on your next rocket. Welcome back to the hobby, have fun!
 
Thanks, dwightr,

Yeah, I am very concerned about weight for the local field.

I've been restoring a 16' wood sailboat, and have learned a few tricks - using chopped glass fiber greatly increases the strength of epoxy allowing you to use less for the same effect. Also, using micro-balloons in non-structural, aerodynamic fillets is a great way to cut weight. It ends up being almost as light as Styrofoam, but hard like plaster when mixed to peanut butter consistency. That, and using aluminum hardware where possible and paint for R/C aircraft instead of heavy rattle-can enamel are some things I will try.

There was a pioneering engineer & inventor named William Bushnell Stout whose motto was "Simplicate and add lightness" that many highly successful aerodynamic engineers adopted as their own. I keep that in mind constantly when working with anything that flies. Watching tons of YT videos on the subject it seems to me that there is a lot of over-engineering done in rockets in areas that are structurally non-critical, or where they are strengthened in directions where the forces are not great enough to warrant them. (Don't get me started on people shoveling on dollops of epoxy!) Heavy steel U-bolts, for one; on some of these big stratospheric monsters they are certainly needed, but an aluminum U-bolt with an aluminum backing plate will still be intact when the rest of the cardboard and craft plywood of a smaller craft is shredded beyond recognition. Steel in a smaller, lighter, slower model is just not a necessity, IMHO.
 
I think you are on the right track. Building heavy is easy, building light takes constant attention to detail. I agree there is a lot of over engineering. Carbon fiber this and titanium that on a mid power or L1 bird is just money that could be better spent on more motors.
 
I broke fins and repaired them on two occasions during many flights. I did fiberglass the fins during the second repair, and never had another broken fin again. However I shortly treed it in the middle of a swamp in FITS (Mansfield, WA) not long after. :( But I think its worthwhile for tough landings, but overkill for flight stresses of an H or I motor. Others might argue for a larger parachute, but not when you have to chase it in the wind, more so when its being dragged across the ground.

I'm in WA (Arlington), as well, and if work & life don't interfere hope to go to FITS this year, as well as more 60 Acre events. I will be joining the Washington Aerospace Club shortly. In fact, it was a visit to a recent fly at 60 Acres that got me fired up (pun intended) about re-joining the hobby.

Yes, you will need the closures. If you go to Aerotech's webpage, on the products tab there is a Motor Matrix that shows the loads that fit the case. Go down a size (or two) if you put in the spacer (or two). If you look at the Resourses tab, you can find instructions for each motor, and it will tell you all the hardware you need (although modified appropriately if you use the RAS). You can also look at CTI or Loki. For G motors in a LOC IV, I always loved the Loki G69 Spitfire (Loki's sparky).

Tim on the Apogee videos is sometimes confusing; on his video regarding the Reload Adapter Kit I believe he says you won't need the aft closure, so i got confused about that. And, i am still a little confused about some of the differences (other than size) regarding 29mm vs. 38mm. If I am understanding it correctly, many 29mm motors are not considered HAZMAT, when the 38mm equivalents are...? I'm having a difficult time find simple & straightforward explanations regarding performance comparisons between the two.

Aeropack has an elegant and simple to use adapter if you have an Aeropack retainer.

I do plan on buying the Aeropack retainer, so I really need to look into this, especially if i can get good flights for less $$.

thanks for the comments!

C
 
I am very close to pulling the trigger on a LOC IV as a mid-power flyer to get back in to the hobby. I plan on adding an e-bay and body extension to fly as a high-power, dual-deploy L1 Cert machine at the high-power site 4 hours from my home in Western Washington later this Spring.[...]
I am concerned about the 1500g weight restriction a my local mid-power restricted field, but am also concerned about recovery, especially as our local field is a large athletic field complex, but still surrounded by roads, trees, other people, etc., within drifting distance of a main/apogee release on a windy day. In anyone's experience would a dual-deploy set up, as I have outlined above (with special care taken to minimize epoxy with chopped glass strengtheners, micro-balloons in aerodynamic fillets, etc.) on a LOC IV, still be too heavy to meet the maximum weight standards? I considered the ChuteRelease system, but the price...yikes...

Curtis,

Welcome back to the hobby!
I've never heard of any club declaring that mid-power is somehow weight-limited to 1500g (vs. motor impulse), but if yours does, Loc IV is probably a not the best candidate.

LOCs own web site declares it as a 3 lbs (1360g) rocket without motor, so you will bust through 1500g limit as soon as you insert a motor. Or apply glue. Or even think of adding dual-deploy eBay.
https://locprecision.com/product/loc-iv/

If you like LOC, look at any of their other options at < 2.0 lbs dry weight.
Or something paper+plywood from www.madcow.com.

Maybe even < 1.5 lbs if you want to fly dual deploy at the mid-power field, as battery and eBay weights add up quicker than you think.

The rest of your hardware choices are perfectly fine.
AT has 38/120 case that accommodates four (4) G-motors. Or you can buy 38/360 and fly with 38-mm RAS adapter on G through I motors. I've done it both ways, prefer 1 case for each motor size, but that costs more money.

JL ChuteRelease is a wonderful device, that makes dual-deploy superfluous.
I still build and fly dual-deploy for larger rockets, but for anything < 10 lbs, JL CR + JL altimeter 3 are far far easier, and require way less prep time. If you are having fun with one, you will end up doing both approaches, eventually.

For the first mid-/high-power build after a hiatus, I would consider starting with something simple. Then complicate things later. Unless you enjoy a challenge from the get go.

And yes, this hobby is not the cheapest. But also not the most expensive.
If budget is somewhat constrained, consider pursuing challenging builds in low-power space, of which there are plenty!

Good luck,
a
 
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Curtis: Welcome back to the hobby. Just want to recommend that you download a copy of Open Rocket or maybe RASAero (freeware) or buy Rocksim, I'm assuming after all that you haven't already. You'll be able to answer a lot of your own questions.
 
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I did both my level 1 and level 2 with a 4" Madcow Torrent Dual Deploy assembled with titebond wood glue, no epoxy with no problems.
Weight was 4 lb. 2 oz. before motors. Yep, a lot of heavy steel hardware, which kept it low which made it more likely I'd get it back.
You might want to consider single use motors. Big selection and price isn't bad, especially when that expensive motor hardware disappears into a swamp.
 
1500g is the upper limit for a class 1 rocket.1501g is a class 2 rocket and requires an FAA waiver. there are 2 loads for the 38/120 case (G61 and G67). 2" - 3" diameter rockets are usually good choices for midpower rockets(less than 1500g pad weight and less than 125g of propellent). my suggestion is to stay with 24 - 29mm motors (G and below) for your midpower rockets.
Rex
 
The LOC IV is a bit big for a mid-power rocket. You can easily exceed the weight limit of 1500 grams without adding any mods. Your plan sounds great for Level 1! You could even test the rocket and RRC on a G61 or G67 before certifying on an H. (The LOC IV flies great on an H123.)

The Reload Adapter System is the front closure for your motor casing, so you would also need a rear closure. It allows you to fly reloads for 38/120, 38/240, and 38/360 in the 38/360 case by adding spacers for the shorter reloads. It is a bit heavier than a standard front closure, and using a G reload for a 38/120 case in a 38/360 with RAS adds considerable weight compared to a normal 38/120 motor. For a LOC IV you would typically be flying 38/120and 38/240 motors.

I like the RAS for the versatility and ability to use available reloads, but I would suggest a bit of reloadable motor experience before trying one. I have them in 29, 38, and 54mm versions, and they are useful, but add a bit of complexity.

You might look into other mid-power kits that use 24mm or 29mm motors, and save the LOC IV for when you are ready to certify. Perhaps a LOC Graduator, which will fly on anything from D to H. Well under 2 pounds ready to fly, and great on small fields with a E30.

I avoid aluminum hardware and any use of swivels, since they are consistent failure points. Appropriately sized steel hardware works better for me. And I have not had any problems with not using a swivel.

The shock loading on even a small rocket can be considerable it deployment is not right at apogee, so you can go stronger and have a zipper, or go lighter and have a separation.
 
Dont forget about Eastern Washington we have one of the best (the best IMO) flying fields in the NW, hundreds of acres of sod farm. Tri-Cities Rocketeers NAR #736, and Tripoli Southeast Washington call it home, we have upcoming events April 6th, May 4th, and a 3 day event June 7th-9th, 2019.


A view of the field at last years SodBlaster event, ironically there was no sod on the field we launch from normally.
SodBlaster 2018 HPR Pads Saturday2.jpg

www.tricitiesrocketeers.org
 
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Tim on the Apogee videos is sometimes confusing; on his video regarding the Reload Adapter Kit I believe he says you won't need the aft closure, so i got confused about that. And, i am still a little confused about some of the differences (other than size) regarding 29mm vs. 38mm. If I am understanding it correctly, many 29mm motors are not considered HAZMAT, when the 38mm equivalents are...? I'm having a difficult time find simple & straightforward explanations regarding performance comparisons between the two.

I misunderstood what you were getting at earlier. The Reload Adapter System (RAS) includes a forward floating closure (with threaded retaining ring) that can substitute for the regular forward closure. The Aft closure is still needed with or without spacer/RAS. See the 38mm RAS instructions from the Aerotech webpage. The Apogee website has a good photo so you can see the parts. So at a minumum you could just order the case, aft closure, and RAS.

https://www.aerotech-rocketry.com/u...f01c8f083_38mm_reload_adapter_anchor_inst.pdf

HAZMAT Shipping is not really straightforward, but it boils down to the weight of an individual separable grain. Something like <30g, if each grain is packaged individually. Most (not all) Aerotech 29mm RMS motors meet this, and some 38mm Aerotech RMS motors meet this. Single use motors don't have seperable grains, so any motor with >30g will have HAZMAT shipping. Most LOKI 38mm motors are not HAZMAT. The obvious way around HAZMAT shipping is to buy from your onsite vendor, if the field has one. Or get in on large group orders to minimize HAZMAT.

This thread has some more details: https://www.rocketryforum.com/threads/list-of-motors-that-dont-require-hazmat-charges-to-ship.70480/
 
Wow, thanks everyone! I really appreciate the input! There is a lot of food for thought here, and I really appreciate the time that you have all taken to respond.

Dont forget about Eastern Washington we have one of the best (the best IMO) flying fields in the NW, hundreds of acres of sod farm.

It's nice to hear about the Tri-Cities launches and it's a possibility, even though that is a bit of a hike for me. I worked on a video shoot at the LIGO Observatory in Richland and, man, that was a long drive! On the other hand, I just watched the FITS video from last year and, frankly, Mansfield looks fraught with danger & difficulty for recovery (even if you don't count wading through waste-high sage brush in rattle snake & tick country). There must be a better place to launch rockets in all that prairie and it sounds like you have it :)

Welcome back to the hobby. Just want to recommend that you download a copy of Open Rocket or maybe RASAero (freeware) or buy Rocksim

Thanks, Wallace, I did download Open Rocket, but haven't played with it too much yet. I understand that using profiles for RockSim in it produces errors...? But I will find the LOC IV profile and see how it does. It should get me in the ball park or at least give me a good idea of relative performance with different motors regardless of any possible errors providing they are consistent.

I also appreciate everyone's input on the LOC IV. I have to say that I am partial to big, low & slow; the high/fast screamers don't do much for me, and so that was one thing that attracted me to the IV. I was thinking something along the lines of the Mad Cow Super DX3 as an L1/L2 ship, but then figured I would pretty much have that if I added a 8" e-bay and body tube extension as a high-power conversion to the LOC IV.

Complexity does not scare me off, frankly. I have played, studied or worked in aviation pretty much my entire life and have very good fabrication & mechanical skills, and really enjoy the challenge of diving into the deep end end of the pool without water wings ;) I'm already considering dual-altimeter redundancy for dual deploy and wondering how one might mount a small 360/VR camera on a rocket; I think putting on some goggles and experiencing a rocket flight in that way would be especially intense...

I like the RAS for the versatility and ability to use available reloads, but I would suggest a bit of reloadable motor experience before trying one. I have them in 29, 38, and 54mm versions, and they are useful, but add a bit of complexity.



DaveW6DPS & wjmoser, thanks for the information - it will be very helpful! I am going to have to get out the calculator, info sheets and make a spreadsheet on weights & performance of various motors and mounts and figure out how I am going to power this thing and make the mid-power limits. I was hoping that with the convertible configuration I could have my cake and launch it, too, while keeping with my penchant for big, slow & low, but I guess the bottom line is what it weighs in at after it's built as to whether or not it is feasible.

Thanks, again! I am usually leary of hobby forums on the 'net, as...well, I'll just leave that there, but this seems like a good group :)

Curtis
 
I'm already considering dual-altimeter redundancy for dual deploy and wondering how one might mount a small 360/VR camera on a rocket; I think putting on some goggles and experiencing a rocket flight in that way would be especially intense...
That I have not heard of being done yet; cool idea.
 
DaveW6DPS & wjmoser, thanks for the information - it will be very helpful! I am going to have to get out the calculator, info sheets and make a spreadsheet on weights & performance of various motors and mounts and figure out how I am going to power this thing and make the mid-power limits. I was hoping that with the convertible configuration I could have my cake and launch it, too, while keeping with my penchant for big, slow & low, but I guess the bottom line is what it weighs in at after it's built as to whether or not it is feasible.

Thrustcurve.org is useful for running batch simulations on all motors available for that size rocket.
 
If you are only interested in G-I, no need for 38mm motors. 29’s cover that gap, are lighter and a fair bit cheaper. Plus if you fly AT motors, you can get the majority of them without hazmat. The only downside is you can’t get your L2 with it but most will tell you that should be a different build anyway. BTW, long 29mm I’s are crazy impressive.
 
The cost of rocketry makes it painful to "learn from your mistakes," however, I often find that this is necessary. But with your background in building things, epoxy knowledge, etc., you are way ahead of the game. Keep asking good questions, and you will keep getting good answers. The folks here are great.

In the end, I hope you look back and say, "That was easier than I thought!"
 
That I have not heard of being done yet; cool idea.

This one is small and light enough to do the trick. Spin stabilization would have to be spot on, or actively guided (better yet) to keep the viewer from getting sick, and you would have to find an optically clear dome for a nose cone, but all of this is very doable.

How cool would it be to sit on the top of your rocket and go for a ride in 360 VR...?

https://www.insta360.com/product/insta360-onex
 
This one is small and light enough to do the trick. Spin stabilization would have to be spot on, or actively guided (better yet) to keep the viewer from getting sick, and you would have to find an optically clear dome for a nose cone, but all of this is very doable.

How cool would it be to sit on the top of your rocket and go for a ride in 360 VR...?

https://www.insta360.com/product/insta360-onex
Have a barf bag handy....if the rocket has much roll you might need it.
 
From Seattle, Tri-Cities is just as much driving time as Mansfield. I'm not sure how that balances for Arlington since you're a bit closer to Highway 2. Anyway, it takes a while to get to either one from the green side. Recovery in Mansfield isn't really that bad, you just have to look down as well as out so you don't put a foot in a tumbleweed or a gopher hole. I have seen one tick, but no rattlesnakes there.

If it was my rocket and I was planning on mainly flying F-G, I'd put a 29mm motor mount in. That will cover you for F-I motors and will be a lot easier to fly and recover at 60 Acres. Not sure how much those weigh dry, but you might need to do some fancy footwork to get an F to have enough thrust to fly. You'll still be able to put an H or I to get an HPR cert and fly under an FAA waiver.

Another nice thing about 60 Acres is that when it's not soccer season (November-late May/early June), you can come down and fly any time with your own launch gear. I'm there most every Sunday morning with the TARC team I'm mentoring. Also, if you're flying F motors or smaller, the south side of the field is a lot less swampy than the north side in the rainy season.
 
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