Loki Research Arts ?

I have purchased a Loki ARTS altimeter recently and have used the supplied software to communicate with the alt. All communications work and function except being able to test fire appogy and main charges from within the software. When I try to test, the alt. it will beep a few times and the software indicates no communication with alt. even though it beeps. This has happened using 2 different computers (laptop & PC).
I can not risk a rocket if I can't verify that the ematches will work with this alt. Has anyone experienced this before or have any suggestions? I thought I would ask on this forum before contacting Loki.

My ARTS works fine. I fired both apogee and main using the computer. As long as I could download from the ARTS, it worked. May want to call Jeff at Loki. They will find out what's going on. Good Luck.

Originally posted by rms
I can not risk a rocket if I can't verify that the ematches will work with this alt. Has anyone experienced this before or have any suggestions? I thought I would ask on this forum before contacting Loki.

Click to expand...

...except that now, some may read this and wonder "Is the ARTS a piece of junk?"

Contact Loki; they're good people and I'm confident will help you out quickly.

-Kevin

Originally posted by rms
I have purchased a Loki ARTS altimeter recently and have used the supplied software to communicate with the alt. All communications work and function except being able to test fire appogy and main charges from within the software. When I try to test, the alt. it will beep a few times and the software indicates no communication with alt. even though it beeps. This has happened using 2 different computers (laptop & PC).
I can not risk a rocket if I can't verify that the ematches will work with this alt. Has anyone experienced this before or have any suggestions? I thought I would ask on this forum before contacting Loki.

Click to expand...

What OS's are you using?

The Altimeter should beep a few times, and then give you an ascending tone, that means it is flight ready, and has never properly communicated with the PC. What communications do work, and what don't?

Feel free to e-mail me at

dwright at d2 dash tech dot com

I'll work with you to make it right.

-D

I have been in touch with Jeff Taylor @ Loki and Erik Hall @ Ozark Aerospace and they have helped me with the problem. It appears as if I may have been using ematches that are not compatible with the altimeter. I'm going to get some DaveyFire ematches and try with those. I probably should have contacted them first but being inexperienced I wanted to be sure there wasn't something simple I was missing, which ironically could very well be the case.
Thanks guys

The Cosmos ematches from Quickburst worked for me. I have had several flights with my ARTS and they have worked everytime. You may want to try those as well.

I am looking at the full boat ARTS (telemetry and GPS) for my next large project.

What is the altitude range for the ARTS? Can't find any detailed info on the Ozark or Loki Web site.

jeff, if you are out there, is there some way for me to download or obtain a user's manual for the entire system? Want to review in some detail before popping for this bad boy.

Hope this is what your looking for

https://www.lokiresearch.com/Programs/ARTS_Manual_V1.1.pdf

And ARTS are good to 50K and 50g's

Tony

Thanks Tony! Have you used the ARTS before? Any feedback appreciated.

I did not get the GPS model, just the basic Bob model. I have not used it yet. I've been using G-Wiz and RC240K. This is my first recording altimeter. It loaded on to the computer easy enough and was simple to program. I got it for a 54mm min dia rocket. Fits nicely on an 'offset' electronics board. I'll be using it later this year.
Tony

Thanks... I am looking at using this (or RDAS) in my BALLs project, a two stager (N-N or N-M) going well over 30K, and would really like to hear from anyone who has used this system. I'll be using an RRC²X as backup.

I've used mine several times on fairly low flights (3000K). Not like anything you'll be doing though. Very easy to use and program. I especially like the recording feature and all of the data you can get. I do not think you will be disappointed. Hope everything goes well with the flight!!

Barry,
Look at AFC-877 or RocketMotion's [Defy Gravity] Control.
These are SUPERIOR units for smart staging.
FredA

Thanks Fred - still looking at all options. Appreciate the suggestion!

Barry

Barry,

Interesting, I have a similar project at LDRS, and I own a Rocket Motion (aka Defy Gravity Control).
As suggested this is an extraordinarily flexible unit which if the menu driven options aren't enough, can be programmed to do **** near anything under the sun. Since we are firing the M from below, the Mission Control will likely get those duties.

I'd be curious and i know this is a bit far afield from the thread, but pertains to the issue. Question is for a very high impulse staged rocket what is the best strategy re flight computers/recovery.

This is still chalk dust, but what I have come up with so far as to guiding principles for this launch:

1) wherever possible KISS principle reigns, all else is subordinate.

2) NO drag separation allowed.

3) booster and sustainer always separate, barring CATO, and then its almost a given, relying on separate altimeters for deployment charges

4) sustainer ignition dependent of vertical trajectory

5) abort mode is default--i.e., w/o user input via R/C or a clear go signal based on gyro/accelerometer data, the sustainer igntion current is shunted.

I'd be curious as to your notions,
JS

Hi DD -

There'a probably as many theories/opinions as to the best way to do this as there are rocketeers trying!

My project is based on a composite airframe I bought from a local guy on ROL. I am making some minor changes to the structure and reengineering the electronics and recovery to suit my own views. It's about 17' tall and is a 6" diameter design made from filament wound 3/32" FG tubing and 3/16" G10 fins, glassed/CFed to the BT's. The booster is a slip fit (with an 8" long coupler) into the sustainer. Both sections have dual deploy with redundant electronics. It has already flown at least once that I am aware of.

I am planning on using drag separation with dual timers in the upper stage, one controlling a separation charge and the other used for sustainer ignition. The sustainer ignition timer(s) will be activated by a trip wire attached to the booster (actually a slip fit 2-pin connector). The booster also has a redundant pair of altimeters (AltACC2C and MAWD) to handle deployment and a single timer (TBD) for redundancy for the separation charge. I have chosen drag separation to obtain maximum altitude; the separation charges are "just in case". An M2400 or N2000 makes a mess of the coupler on ignition. Why do you say "no drag sep allowed?

Have not found a timer that can sense vertical orientation before firing (i.e. for sustainer ignition). I want to use redundant electronics and the budget won't allow the use of a dual flight computer setup that might do this, though it's not a bad idea.

As far as abort mode, in my opinion the conditions that would cause an abort will be impossible to see above 10-15K anyway; barring a CATO on the pad, or a shred (unlikely on the booster), you'd be reacting too late if using R/C.

The sustainer will have one full boat flight computer (to get accelerometer data, baro data, recovery event timing, and recovery GPS telemetry) and a simple backup altimeter for recovery only. I'll also have dual Walson trackers (one for booster and sustainer) in addition to the realtime GPS data on the sustainer.

This is about as simple as I think I can safely get. Biggest fear is getting the timing wrong on sustainer ignition, or too slow a speed on separation, causing an off-vertical trajectory. I'll be very conservative on the ignition delay (still running sims) rather than going for the last 1K' or so.

But I am very open to comment and suggestions - this is still new territory to me.

I've looked at his project, and I believe the reason for no drag sep is that IIRC, the sustainer ignition elecrtonics are in the booster.

Barry,

I suggested a Control for the sustainer.
It can do everything needed.
I have a two-stage in the works with the following setup for the sustainer.

I plan (count on) drag seperation. I've yet to decide if I'm using a CO2-based seperation charge.

The sustainer's Control will be light the sustainer motor only after three events: Booster burnout ; sustainer velocity drops below a threshold (say 300fps) and the MAD-like circuit on the [pyro-4] input says the sustainer is still vertical.

The Control will also handle apogee and low-alttitude deployment for the sustainer.

This is my idea of "smart staging". Watch the burnout, velocity and angle before you light the motor. Use the computer in your flight computer.

FredA

Originally posted by dbarrym
Hi DD -

There'a probably as many theories/opinions as to the best way to do this as there are rocketeers trying!

My project is based on a composite airframe I bought from a local guy on ROL. I am making some minor changes to the structure and reengineering the electronics and recovery to suit my own views. It's about 17' tall and is a 6" diameter design made from filament wound 3/32" FG tubing and 3/16" G10 fins, glassed/CFed to the BT's. The booster is a slip fit (with an 8" long coupler) into the sustainer. Both sections have dual deploy with redundant electronics. It has already flown at least once that I am aware of.

I am planning on using drag separation with dual timers in the upper stage, one controlling a separation charge and the other used for sustainer ignition. The sustainer ignition timer(s) will be activated by a trip wire attached to the booster (actually a slip fit 2-pin connector). The booster also has a redundant pair of altimeters (AltACC2C and MAWD) to handle deployment and a single timer (TBD) for redundancy for the separation charge. I have chosen drag separation to obtain maximum altitude; the separation charges are "just in case". An M2400 or N2000 makes a mess of the coupler on ignition. Why do you say "no drag sep allowed?

Have not found a timer that can sense vertical orientation before firing (i.e. for sustainer ignition). I want to use redundant electronics and the budget won't allow the use of a dual flight computer setup that might do this, though it's not a bad idea.

As far as abort mode, in my opinion the conditions that would cause an abort will be impossible to see above 10-15K anyway; barring a CATO on the pad, or a shred (unlikely on the booster), you'd be reacting too late if using R/C.

The sustainer will have one full boat flight computer (to get accelerometer data, baro data, recovery event timing, and recovery GPS telemetry) and a simple backup altimeter for recovery only. I'll also have dual Walson trackers (one for booster and sustainer) in addition to the realtime GPS data on the sustainer.

This is about as simple as I think I can safely get. Biggest fear is getting the timing wrong on sustainer ignition, or too slow a speed on separation, causing an off-vertical trajectory. I'll be very conservative on the ignition delay (still running sims) rather than going for the last 1K' or so.

But I am very open to comment and suggestions - this is still new territory to me.

Click to expand...

Barry. I have thought long and hard about drag sep. The curious finding with Rocksim at least as I did my best to sim various interstage delays with and w/o the booster, made very little difference. At first I thought this was BS, but on further reflection
decided that while reducing drag I lost so much mo in the process it was sixes. I know many sounding rockets have used drag sep as well as lots of amateur projects. But if the gain in altitude is small, why mess with it. So the set-up I have envisioned with advice from a friend, CJL, is to place a BP charge that will help to separate the two halves on ignition of the sustainer, but in the event of an abort, use the same charge to effect separation and rely on each flight computer tio get the laundry out,
J

Seperating a two-stage ASAP is almost always a good idea if you care about maximizing altitude.

You dump the drag of the booster ASAP.
You let the sustainer fly as long as possible un-boosted.
Drag is proprtional to velocity square - let the sustainer slow down before ignition.

Just need to be smart....
Watch velocity, not just a [crude] tme delay.
Sense vertical and inhibit if not.

Now - I've seen examples where you don't want to seperate ASAP - One was where the seperation would be at near-mach and waiting allowed the entire airframe to slow so that seperation would occur in less turbulent air.

But play with your sims - delayed sustainer ignition will almost always buy you more altitude.

Freda

Fred,

I'll take your advice and look at the sims again and post when I have some good data. I have no doubt about letting it slow, esp if around mach cuz of potential turbulence...
JS

PS: I ran the sims again, dumping the booster at burnout with drag sep resulted in a roughly 3 percent gain with the same interstage delay of 6 sec. The N-M went from 36 to 37k. What I think is interesting is that this is in spite of the fact the booster is 6" diam and the sustainer 4". Maybe some more tweaking might get additional altitude, but unless I'm doing something wrong big time, I stand by my original statement that it just doesn't make a big difference.




JS

Fred's right, I also wanted to slow down below Mach transition speeds to ensure stable separation.

Fred, I'll look into the Control more, was not aware it had an orientation sensor onboard.

DD, I've been told by more experienced flyers that RocSim et al is not all that accurate with sustained Mach plus events, especially if much time is spent around Mach transition speeds. Just what I've heard, again my practical experience at this level is limited at best.

Is there a forum or chat/discussion where more advanced topics of this type can be discussed? PM me if you'd like.

Thanks!

Originally posted by dbarrym
Fred's right, I also wanted to slow down below Mach transition speeds to ensure stable separation.

Fred, I'll look into the Control more, was not aware it had an orientation sensor onboard.

DD, I've been told by more experienced flyers that RocSim et al is not all that accurate with sustained Mach plus events, especially if much time is spent around Mach transition speeds. Just what I've heard, again my practical experience at this level is limited at best.

Is there a forum or chat/discussion where more advanced topics of this type can be discussed? PM me if you'd like.

Thanks!

Click to expand...

Barry,

First, agreed that rocksim isn't that accurate, or rather the methodology used isn't for flights of these types. I am expecting maybe 27.5k. Another 500 or 1000 via drag sep, doesn't mean a whole lot to me as it is so far out of sight who cares unless you're after a record?

Personal pref I guess, I want to tie the two parts together with nylon shear pins, so that if it waggles a bit or hits wind shear, hopefully it wont come apart prematurely as I have only 4 inches of coupler. Plus the brain is in the caboose, tho obviously I could run wires from above.

The control has a single axis accelerometer on board, this by itself won't help you much. I can see a dense smoke trail easily to ten K which is where I stage, I'm not sure I agree with Fred about not using a chicken switch, its there primarily to guard against excessive weather cock. If I don't feel its going vertically enough, no stage. But a sudden event, agreed no way it will help.

There have been threads here before on horizon sensing, etc. In my next project I'm gonna stream the baro and accel data to a small auxillary pic to estimate the AOA and let the computer decide.

And, yes there used to be an advanced topic forum which is the perfect place for such discussions. Gone for dubious reasons IMHO.

I'll PM my e-mail address. We can discuss this more as our projects are so similar and we are both pushing our personal envelopes I suspect.

DD

The Control can use it's 4th pyro channel as an output or an input.

It does not have a "tilt" sensor, but you can make one and wire it to the 4th channel.

You can then program it to watch for the three things I indicated:
- MECO
- Velocity < some value
- Channel 4's input is in the desired state.

Thus "smart ignition" of the sustainer.

Sorry if I missled you.
FredA

Fred,

Can you describe the type of tilt switch one would use?
John

The only tilt sensor that would work is a gyroscopic one. A simple gravity based one would not work, as it would always detect the rocket's postition as perfectly vertical (during motor burn, straight up, during coast phase, straight down).

It sounds like Fred might be using a magnetometer, but will let him answer,
JS

Really? How would that work. It sounds like a possibility, and I certainly hadn't thought of that, but if it works, then it is definitely something to look into.

Fred?

Guess you could use the same magnetometer sensor as used in the MAD "depoyment at apogee" kit that Aerocon sells. Just need to interface it correctly to the input channels of the Control unit. Hopefully Fred can provide some details.

Details here.

CJ,

I imagine an angle of inclination could be dertermined by interpolation/look up tables but you also need a compass function as well as a rocket leaning north would have a different value than one leaning west by the same amount. I'm curious as well, Fred?
J
PS: I'm thinking the cheap and dirty way to do it would be look at the sensor output at x degrees, say this is your max tolerated AOA, in all the compass directions and average them--this then becomes the threshold for abort.