Loki 98mm Snap Ring Hardware in DOM Tube

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Loki Research

Loki Research

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I know there's been several people waiting to see this for a very long time now.

I am seriously thinking about placing an order for 98mm DOM tubing to make snap ring style hardware from. For a long time I have wanted to do 98mm hardware but I'm only willing to do it with DOM tubing to keep in line with the high tolerance and high quality of products that Loki Research has become known for in recent years. There has been a lot of interest in this lately and I have fielded plenty of emails on the subject in the past 6+ months. I have enough customers standing in line now to help cover a large enough portion of material purchasing costs so I think now could very well be the time. For now, these would solely be for experimental use.

If you have a serious interest in purchasing this hardware, please send me an email with the average case lengths you are wanting along with the quantity. Grain lengths would be ~6" long each. The bulkheads would be scaled up from 76mm with much larger smoke grain cavities and they would use the same high quality Iso-molded graphite nozzles used in the rest of the Loki product line. Tentatively, the case ID/OD dimensions would be ~3.55"ID x ~3.875"OD with IR (individual reading) tolerances and of custom lengths, not modeled after anyone else. Lengths would range from 24" to 69~78" in length. Liner wall thicknesses would be around .093" and casting tube ID would be 3.225" for now. The longer cases would (for myself) only be used with single use composite nozzles.
scott *at* lokiresearch ^dot^ com. Yeah I get enough junk mail as it is. No PM's please as I rarely check them and I like to keep all communications on business in one place.

If you know of someone who might be interested that doesn't come around here much, please send them a link to come here.

Thanks :)
 
Tentatively, the case ID/OD dimensions would be ~3.55"ID x ~3.875"OD with IR (individual reading) tolerances and of custom lengths, not modeled after anyone else. Lengths would range from 24" to 69~78" in length. Liner wall thicknesses would be around .093" and casting tube ID would be 3.225" for now.
Click to expand...

This data is great example why all consumer high power reloadable motors have such a poor performance compared to professional motors. Just some quick calculations:
If you start with the same OD diameter- 3,875˝ (98,4mm).Professional motor would most likely have a 2024 or 7075 alloy casing about 0,080˝ thick, plus a rubber liner/insulation about 0,020˝ thick (or even thinner) with case bonded propellant. This means that the diameter of the propellant grain is 3,675˝ versus 3,225˝ for the hobby motor. If you take that both have the same diameter of the core (let´s say about 1,125˝), this means that a cross section surface of professional motor propellant grain is about 33% larger. Which means that the professional motor packs one third more propellant in the same physical envelope and also has a much lower inert weight. Differences like this and a lot of other clever design choices make it possible to get to very high altitudes with small rockets- for example small 3˝ diameter meteorological rocket Metroc flew to 100.000 feet with only a medium size M motor (8000Ns), or boosted darts flying to 100km with only an O motor.
It seems that state of the art in HPR/EX community is just scratching the surface of what is possible with some clever engineering.
Anyway, just saying. I will crawl back in my hole now.
 
Andrej said:
This data is great example why all consumer high power reloadable motors have such a poor performance compared to professional motors. Just some quick calculations.....
Click to expand...

Your observations are not appropriate in the context of this topic. Reusable research motors have additional requirements and limitations that high-performance, single-use sounding rockets do not have. Obviously, hobbyists could design higher mass ratio rockets for special projects (many do), but they are not going to get there without first testing propellant formulas, grain geometries, and flight systems. You need quality casings and components to do this experimentation, just as the professionals do before optimizing their systems.
 
OK, don't get to excited. It's just my observation that most of HPR/EX motors and rockets in general are designed very conservatively and there is a lot of room for improvement.
 
Nothing prevents one from intentionally turning a nice reusable case into a single-use case-bonded wildcat motor. I choose ( to try ) not to use my budget that way, but one certainly could do so.
 
Andrej said:
OK, don't get to excited. It's just my observation that most of HPR/EX motors and rockets in general are designed very conservatively and there is a lot of room for improvement.
Click to expand...

That is obvious without your post to this thread. If you'd like to discuss the merits of high-performance design options, start your own topic. Or search here for other topics where this has been discussed regularly by people who actually build and fly case-bonded motors to high altitudes.
 
I wholeheartedly support anything coming out of the Loki mad scientist lair, but sadly 98mm is way more than I'll fly anytime soon...

29mm... Then we can talk. [emoji6]

Sent from my LGL44VL using Tapatalk
 
Andrej said:
This data is great example why all consumer high power reloadable motors have such a poor performance compared to professional motors. Just some quick calculations:
Click to expand...

This I would say is a great example of a teaching moment actually. :) Is there a difference in comparison of hobby vs pro-grade motors? Absolutely, but you need to continue on past the differences and ask yourself why the differences are there in the first place. The purpose of having hardware that is “for experimental use” is for the individual to develop motors and propellant reloads for their own use. Motor systems such as you described are, as John indicated, the end result of many hours and dollars’ worth of testing, development and refinement. This typically starts out with hardware such as I am talking about here. You don’t start out with a Formula 1 Cosworth engine that can turn 20,000 RPM, make nearly 800hp, weigh under 300 lbs and NOT put a rod through the block on the 5th lap. You develop it starting with a rock solid, overbuilt engine.

All of the specifications I pointed out are in fact “selling points” to those who know what they are looking at. The hardware and the liners as dimensioned offer a high degree of head room for user error while still maintaining high tolerance standards so that the limitations of the materials used are consistent and repeatable, not random and unknown from hardware set to set.

If anyone were selling the kind of “professional grade” motors that you are comparing to, they wouldn’t be trying to sell them on TRF. No offense to anyone, but the reason this is all “hobby use” is because it is affordable enough for the hobbyist, and as hobbyists, many are still learning the art, not mastering it the way the motors you’re describing have. I don’t think most of us here (myself included) could afford the true cost and price tag of a real high performance, reliable and repeatable professional grade motor, let alone the shipping costs that a motor made to those standards is going to require, in the low to mid 4 figure range. Not to mention with the safety margin limitations that the NFPA 1125 puts on hobby motors,(which you're likely not even aware of being outside the USA) it’s virtually impossible to reach the same performance results, thus the difference between hobby and pro-grade. Sure there's room for improvement, but that level of improvement is not needed, not in this market and as I said, not for hobby prices. It's just not doable here.

So when you say that the “state of the art in HPR/EX community is just scratching the surface of what is possible with some clever engineering”, you are not considering “why” there is a difference between the two, only that there is a difference, which isn't really fair. It's not that we can't reach it. We're even not trying to because we're not allowed to. Hopefully you understand the “why” now and can see where both have their place in their respective markets. Hopefully you (and others) also have a better understanding now for the value and the place that these 98mm snap ring motors have in this market place.
 
Scott - can we specify how many grains we want and then you will figure out the required length based on what's needed for the nozzle and forward closure? If not, can you post the lengths of the nozzles and forward closures?

Thanks for making these available,


Tony
 
Tony,

Yes, giving me the number of grains you want for each hardware set would be the best thing to do. I mentioned above that the grain length would likely be about 6" long. That makes for a slightly progressive thrust profile, but it is consistent with the legacy 98mm Loki hardware.

Thanks for asking.
 
For that matter, 7075 is not a good choice for case material. It doesn't like elevated temps...

Gerald
 
Andrej said:
OK, don't get to excited. It's just my observation that most of HPR/EX motors and rockets in general are designed very conservatively and there is a lot of room for improvement.
Click to expand...

It's almost as if hobby casings are designed to be used more than once....
 
Loki Research said:
This I would say is a great example of a teaching moment actually. :) Is there a difference in comparison of hobby vs pro-grade motors? Absolutely, but you need to continue on past the differences and ask yourself why the differences are there in the first place. The purpose of having hardware that is “for experimental use” is for the individual to develop motors and propellant reloads for their own use. Motor systems such as you described are, as John indicated, the end result of many hours and dollars’ worth of testing, development and refinement. This typically starts out with hardware such as I am talking about here. You don’t start out with a Formula 1 Cosworth engine that can turn 20,000 RPM, make nearly 800hp, weigh under 300 lbs and NOT put a rod through the block on the 5th lap. You develop it starting with a rock solid, overbuilt engine.

All of the specifications I pointed out are in fact “selling points” to those who know what they are looking at. The hardware and the liners as dimensioned offer a high degree of head room for user error while still maintaining high tolerance standards so that the limitations of the materials used are consistent and repeatable, not random and unknown from hardware set to set.

If anyone were selling the kind of “professional grade” motors that you are comparing to, they wouldn’t be trying to sell them on TRF. No offense to anyone, but the reason this is all “hobby use” is because it is affordable enough for the hobbyist, and as hobbyists, many are still learning the art, not mastering it the way the motors you’re describing have. I don’t think most of us here (myself included) could afford the true cost and price tag of a real high performance, reliable and repeatable professional grade motor, let alone the shipping costs that a motor made to those standards is going to require, in the low to mid 4 figure range. Not to mention with the safety margin limitations that the NFPA 1125 puts on hobby motors,(which you're likely not even aware of being outside the USA) it’s virtually impossible to reach the same performance results, thus the difference between hobby and pro-grade. Sure there's room for improvement, but that level of improvement is not needed, not in this market and as I said, not for hobby prices. It's just not doable here.

So when you say that the “state of the art in HPR/EX community is just scratching the surface of what is possible with some clever engineering”, you are not considering “why” there is a difference between the two, only that there is a difference, which isn't really fair. It's not that we can't reach it. We're even not trying to because we're not allowed to. Hopefully you understand the “why” now and can see where both have their place in their respective markets. Hopefully you (and others) also have a better understanding now for the value and the place that these 98mm snap ring motors have in this market place.
Click to expand...

Well said Scott.
 

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