Behold the Loki 38mm 1200

I just got this Loki 38mm 1200 case in the mail today, and I might add that it's a fine high quality piece of work! That's 25" inches of pure J motor there, it doesn't get any better than that!

I built two rockets around this motor and I cant wait to let her fly.

And soon there will be many new reloads for this case. (no pressure Scott):wink:


TA

Than is one beautiful case.

Flew one this last Saturday at Thunderstruck. Scott provided a pre-release J-1127 Blue which I flew in my "Blue Hawk 38" (yes, Black Hawk painted blue). Mach 1.4 (although it looked much faster than that) to 13,308 ft.

dixontj93060 said:

Flew one this last Saturday at Thunderstruck. Scott provided a pre-release J-1127 Blue which I flew in my "Blue Hawk 38" (yes, Black Hawk painted blue). Mach 1.4 (although it looked much faster than that) to 13,308 ft.

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Was that a Raven flight?

I flew the J1000 on the same rocket, we should compare data.

That is an Great looking motor and it is a blast to fly.

GRIFFIN said:

Was that a Raven flight?

I flew the J1000 on the same rocket, we should compare data.

That is an Great looking motor and it is a blast to fly.

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Yes it was (using your recommended Ch3/4 as backup). I have a J1000 also, but opted for the Blue. BTW, did get some "expert" comments from Reese regarding non-linearity of accelerometers and such as he also doubted such a low velocity readout. If I do just an altitude vs time plot I get something like Mach 9 right before burnout, but that has to be flawed somehow too. Wish we just had a SUPER ACCURATE acel-based alt for these speed contests (are you listening Jolly Logic? This is the chance to expand your market share with the Altimeter 3 "Extreme" ).

dixontj93060 said:

BTW, did get some "expert" comments from Reese regarding non-linearity of accelerometers and such as he also doubted such a low velocity readout.

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Yah, I did a bad job of summarizing this post by someone who knows far more than I do about these sorts of things: https://www.rocketryforum.com/showthread.php?47042-Electronics-at-100-000&p=458319#post458319 (et seq.)-- it appears it's not just the accel that's in doubt but also the ADC...

daveyfire said:

Yah, I did a bad job of summarizing this post by someone who knows far more than I do about these sorts of things: https://www.rocketryforum.com/showthread.php?47042-Electronics-at-100-000&p=458319#post458319 (et seq.)-- it appears it's not just the accel that's in doubt but also the ADC...

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Well, unfortunately David Schultz is not designing an altimeter for sale to the public (as far as I know). I have a number of altimeters from a variety of manufacturers... It would be great to know if at least one of them could do accurate velocity measurement (certainly much better than +/-20% on any 1/3rd) ;(

Turns out mine was flow with an SL100. Oh well, here is the data.


Sorry for de-railing your thread.

View attachment BlackHawk 38 Loki J1000 MWPX.pf2

My flight from Saturday:

View attachment Blue Hawk.FIPa

Sorry for de-railing your thread.

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Derailed, rolled at least three times before bursting into flames and basically totally destroyed. It is a nice motor though.

Steve G

dixontj93060 said:

Well, unfortunately David Schultz is not designing an altimeter for sale to the public (as far as I know). I have a number of altimeters from a variety of manufacturers... It would be great to know if at least one of them could do accurate velocity measurement (certainly much better than +/-20% on any 1/3rd) ;(

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No altimeters perform a direct velocity measurement. They can integrate the accelerometer data to get velocity or take a derivative of the barometric data to get velocity. To obtain a direct measurement of velocity of a rocket you need to incorporate a Machmeter which requires a pitot-static system.

Bob

bobkrech said:

No altimeters perform a direct velocity measurement. They can integrate the accelerometer data to get velocity or take a derivative of the barometric data to get velocity. To obtain a direct measurement of velocity of a rocket you need to incorporate a Machmeter which requires a pitot-static system.

Bob

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Bob, I do understand that, but with a combination of a "premium" accelerometer and an A/D convertor could we get more accurate results than we have today? /Tim (as BTW, in general in these velocity contests the derivative of baro data is not accepted).

Well all I have to say is if you want to get to mach 2 the loki 1200 might be the way to get there!

TA

dixontj93060 said:

Flew one this last Saturday at Thunderstruck. Scott provided a pre-release J-1127 Blue which I flew in my "Blue Hawk 38" (yes, Black Hawk painted blue). Mach 1.4 (although it looked much faster than that) to 13,308 ft.

Click to expand...

These high l/d ratio motors always look faster because of erosivity at start up. The acceleration is quite startling to those who are not used to it. I've had some 38mm motors that smashed launch pads even though they've been launching M's and N motors off of them all weekend.

...I think this is the reason for me to want L2 and not just L1.

Just watch the video of the violet and tell me that you don't have to have one! :headbang:

[video=youtube;ku6vyZoPEbY]https://www.youtube.com/watch?v=ku6vyZoPEbY[/video]

TA

Want... Can't afford... Would do anything to get one... (except pay full price)

blackbrandt said:

Want... Can't afford... Would do anything to get one... (except pay full price)

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So you won't do literally the easiest thing to get one...yet you'll do anything?

That's stupid.

However, I can't afford one of these.... All I can do is watch them...

dixontj93060 said:

Wish we just had a SUPER ACCURATE acel-based alt for these speed contests (are you listening Jolly Logic? This is the chance to expand your market share with the Altimeter 3 "Extreme" ).

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I hear ya...

I just have to say, as someone who loves the 'lectronics--I've got mixed emotions about putting some love and attention into a product that you FULLY intend to be so mean towards. You realize those narrow diameter rockets and XL short-burn motors are like hitting them with a hammer, right?

;-)

As for accuracy, a rocket is a straight shot, and integrating an accelerometer is by far the most cost-effective way to go, especially when you factor in installation costs and portability versus pitot-tube systems. The accuracy is not bad if the mount is sensible, the vibration is managed, and the rocket doesn't corkscrew. Most mach+ rockets that don't fly straight have bigger problems than innaccurate speed measurements, as you know.

Be careful differentiating pressure readings unless you've got a really well-vented payload section and you're sure you're not getting a rapid venturi effect (low pressure) during boost. A reading that seems to really jump up crazy fast (like mach 9) is probably due to this effect. It's not low pressure due to altitude, but rather due to the low pressure zone beneath the bow wave. If that makes sense.

John Beans said:

I hear ya...

I just have to say, as someone who loves the 'lectronics--I've got mixed emotions about putting some love and attention into a product that you fully intend to be so mean towards. You realize those narrow diameter rockets and XL short-burn motors are like hitting them with a hammer, right?

;-)

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As they say, "No pain, no gain!"