With a little help from my friends: 2-stage 54mm min diameter

[waltr]

Wow, all the things that could go wrong.....
At least there isn't much damage.

I do fly a 2-stage and have 2-3 fully successful flights out of a dozen. something doesn't work properly in most.

I suspect you need a bit more N-s in the booster motor. That will get the minimum altitude (LDA) and Velocity needed to keep the Quantum happy.

Add some glue and try it again..

 

[rocketace]

I suspect you need a bit more N-s in the booster motor. That will get the minimum altitude (LDA) and Velocity needed to keep the Quantum happy.

Yeah, bigger motor would make the Quantum much more happy. I will most likely replace this with a Raven so I have more options, and move the Quantum to another rocket.

 

[rocketace]

Again its ben awhile since an update, but here we go.

The 2 main issues on the last flight was not getting enough kick of the pad because I was trying to keep it low and slow, and sustainer recovery was packed tight. I fixed the tight recovery by switching to a TopFlight Parachute and changing out the nylon for Kevlar. Now there is more than enough room for everything to slide around. I used the same sustainer motor G79W but for the booster I used a I435.

I also have a BlueRaven that is in the sustainer replacing one of the RavenV4s. The Blue raven will be used for Primary deployment changes and will also be hooked up to a light for sustainer ignition (not the ignitor for this flight). The RavenV4 will be controlling the back up deployment charges and the actual sustainer ignition.

The flight was great with way too much data to go though. But Ill try to give the highlights.

What worked: Boost was great, separation was good, it stayed within tilt limits, ignitor worked, sustainer boost was good, and all recovery was nominal and not too far from the pad.

Boost all looking nominal! Boost photos by Harry Spears


Sustainer recovery: Cord cutter holding everything together. (The white wire is the sustainer ignitor umbilical)


Sustainer recovery: Cord cutter has cut and main being deployed!



There are still a list of improvements for the next flight.

1) The BlueRaven lit its light right at booster burn out instead of when “I thought” I had it programed. I was overlooking the secondary setting. Both primary and secondary setting needs to be configured. Awesome feature that I will be using but it slipped my mind. That’s what testing is for!
2) I was hoping for a little coast before ignition, but the way I had the RavenV4 programed it lit almost right at separation. Next flight I will put a larger T> value it has to pass before ignition.
3) with the booster in the next flight going +2K I will be adding the cord cutters to the booster as well.
4) I am replacing the Quantum in the booster with a RavenV4. This change will also carry over to the 54mm rocket to reduce space required.
5) Since both sections landed close I was not looking at the GPS systems. Even though I am sure everything worked fine, I could not verify it. This will have to be done on the next flight.

For 2Testys next flight and final needed test flight it will be launching on a J500 -> I205.
-The BlueRaven will control the sustainer ignition. RTOM3 will still ride along for data, but probably wont fly it after this one.


For the 54mm part of the project, I am waiting on a good time to meet up with my buddy to layup the tubes. I am also working on the av bay layout. Switching to the BlueRaven has simplified it and gave me a few options to think about.

Nose cone set up with 2 Ravens, GPS, camera, dual pull pin, and magnetic switch. Still needs several tweaks until I start creating the plastic support however the current idea is to do it in modular sections that bolt together. So there will be a top section for the Ravens&GPS that bolts to a middle battery section and then a lower switch / camera section.

Then this is the interstage coupler with a Raven, AltDuo, GPS, dual pull pin, and a magnetic switch.

 

[bad_idea]

That was a great flight, Jason. Glad I was there to see it. Looking forward to your 54mm!

 

[rocketace]

That was a great flight, Jason. Glad I was there to see it. Looking forward to your 54mm!

Thanks Stephen! Hopefully I can make some building progress someday. I have let this project linger so long. It's been hard to find time to sit down and really work on it.

 

[rocketace]

Starting to finalize the Raven programing for my next 2-Testy flight with the J500-I205.

I start with lots and lots of sims with different delays in separation and ignition to try and find a sweet spot. For my previous flights I wanted to keep it low to the ground so I could see all the recovery so all the events happened pretty quick. Now that I am confident in my recovery set up, time to get a bit higher! For this flight I have a small delay after booster burn out, then separation, another small delay before sustainer ignition. Also, programing a backup to ignite the sustainer right after separation if the angle is not optimal.

I start with lots of simulation from 0-20 degrees with lots of different separation and ignition delays. What I have been doing is starting with a sustainer ignition delay that is way too long and then working back to see where I want it. For this flight I wanted the sustainer to be going no less than 250ft/s when the motor comes up to pressure. I hope the motor comes up to pressure instantly, but I am giving it a full second.


First, the booster motor burns for 1.4 seconds.
I think I have noticed that the Raven has about a 0.15 second delay in sensing or triggering liftoff. So I also account for this.
Next, I wanted a little delay before the separation just to watch it in the sky. I decided on 1 second.
With this set up the sustainer falls to 250ft/s at T=5.5s, so I am setting the ignition to happen latest around 4.5s.

To help keep everything straight in my mind I write the flight sequence out like this. It really helps when trying to figure out the programing.



Now for the BlueRaven programing I am basing it off what Adrian has posted previously in one of this staging threads. Output 4 will be connected to the sustainer ignitor. The Primary will be if it has a nice straight boost. The secondary will be if it starting to angle more than desired. For both the rocket has to have sensed motor burn out, be at lease 1000ft up, currently less than 20 degrees and during the flight has never exceeded 45 degrees. If everything is nice and straight, as soon as the rocket slows to 300ft/s it will tonight. If it is thinking the future angle (+3s from current) is exceeding 12 degrees then it will fire.

The RavenV4 in the booster will control the separation charge and will simply look for booster burn out and flight time > 2.5s

I am still a noob at programing 2-stage flights. So let me know if you see anything out of place.

 

[manixFan]

Great write up! Thanks for all the info on programming, very helpful to us 2 stage wannabes.

I hope to see one of your 2 stage flights at Seymour in person. But the photos by Harry and your in-flight stills are a good substitute.

Congrats on the flight.


Tony

 

[rocketace]

Thanks Tony!
I still consider myself a 2-stage wannabe. Let’s see how this next flight goes… Now I just need to prep the recovery and find a good weekend.

 

[Adrian A]

Now for the BlueRaven programing I am basing it off what Adrian has posted previously in one of this staging threads. Output 4 will be connected to the sustainer ignitor. The Primary will be if it has a nice straight boost. The secondary will be if it starting to angle more than desired. For both the rocket has to have sensed motor burn out, be at lease 1000ft up, currently less than 20 degrees and during the flight has never exceeded 45 degrees. If everything is nice and straight, as soon as the rocket slows to 300ft/s it will tonight. If it is thinking the future angle (+3s from current) is exceeding 12 degrees then it will fire.
View attachment 590756
The RavenV4 in the booster will control the separation charge and will simply look for booster burn out and flight time > 2.5s

I am still a noob at programing 2-stage flights. So let me know if you see anything out of place.

This looks very reasonable to me.

 

[bad_idea]

Starting to finalize the Raven programing for my next 2-Testy flight with the J500-I205.

I start with lots and lots of sims with different delays in separation and ignition to try and find a sweet spot. For my previous flights I wanted to keep it low to the ground so I could see all the recovery so all the events happened pretty quick. Now that I am confident in my recovery set up, time to get a bit higher! For this flight I have a small delay after booster burn out, then separation, another small delay before sustainer ignition. Also, programing a backup to ignite the sustainer right after separation if the angle is not optimal.

I start with lots of simulation from 0-20 degrees with lots of different separation and ignition delays. What I have been doing is starting with a sustainer ignition delay that is way too long and then working back to see where I want it. For this flight I wanted the sustainer to be going no less than 250ft/s when the motor comes up to pressure. I hope the motor comes up to pressure instantly, but I am giving it a full second.
View attachment 590754

First, the booster motor burns for 1.4 seconds.
I think I have noticed that the Raven has about a 0.15 second delay in sensing or triggering liftoff. So I also account for this.
Next, I wanted a little delay before the separation just to watch it in the sky. I decided on 1 second.
With this set up the sustainer falls to 250ft/s at T=5.5s, so I am setting the ignition to happen latest around 4.5s.

To help keep everything straight in my mind I write the flight sequence out like this. It really helps when trying to figure out the programing.
View attachment 590755


Now for the BlueRaven programing I am basing it off what Adrian has posted previously in one of this staging threads. Output 4 will be connected to the sustainer ignitor. The Primary will be if it has a nice straight boost. The secondary will be if it starting to angle more than desired. For both the rocket has to have sensed motor burn out, be at lease 1000ft up, currently less than 20 degrees and during the flight has never exceeded 45 degrees. If everything is nice and straight, as soon as the rocket slows to 300ft/s it will tonight. If it is thinking the future angle (+3s from current) is exceeding 12 degrees then it will fire.
View attachment 590756
The RavenV4 in the booster will control the separation charge and will simply look for booster burn out and flight time > 2.5s

This is extremely informative, Jason. Thank you for posting it. Helps my own thinking as I work towards my airstart testing and eventual staging (nearly two years behind my original schedule!).

 

[rocketace]

(nearly two years behind my original schedule!).

Thanks and glad it helped. And I started thinking about this project almost 3 years ago… somehow life always delays everything.

 

[rocketace]

Next big step done. The first (probably sustainer) tube was laid up. After lots of thinking and guessing I decided to do 6 layers of 3k Twill. I know this is way overkill for strength, but it was needed to get the OD large enough. The larger OD is needed to match up with the NC and more importantly give clearance for the tail cone.

The fun getting started.


6 Layers of CF one and now for the peel ply.


And here it is with the peel ply. Not perfect, but definitely one of my best layups yet.



Matches almost perfect with the NC.


Wrapping a piece of cardstock over the tube to simulate the expected ID of the exterior coupler. Both AT and CTI tail cones slide in without hitting the paper so I know the OD of the airframe should be good for the design. I just hope it's uniform enough to make a coupler that slides nicely.

 

[rocketace]

While waiting for the next launch of the 2-Testy rocket, I have been playing around with the electronics. Sadly I have decided at this moment to eliminate the camera. First off I know with the heat it produces and the heat at most of my launches, there is a low possibility of the camera staying on. Secondly, it adds a lot of complication (arming, port hole, heat isolation) and it takes up a lot of space.

Here was the original that included the camera, RTOM3, Eggtimer Wifi switch and all the pull pin switches.



This was the last update that included the camera. The BlueRaven eliminated the need for the RTOM3 & Wifi Switch. This drastically reduced the volume needed and complexity.


And this is the current configuration. BlueRaven, RavenV4, FW-GPS. Each has its 3.7V battery and a magnetic switch (instead of pull pin). The light grey block is a single pull pin that will be the sustainer ignitor disconnect / shunt.


Next big step will be to actual design the 3D printed structure that will hold all this in place.

 

[manixFan]

Now that all the Featherweight stuff uses 4-40 screws, I’ve been using heat-set brass inserts in all my 3D printed mounts. (Older Ravens used 2-56 screws). I just use a special tip on my soldering iron to press the inserts into place. The versions I found seem to hold better than ones that were originally designed for ultrasonic insertion. I don’t recall if you’ve mentioned using them before, but if not, I think they are worth the small bit of extra effort.


Tony

PS: that mag switch layout might be a bit of a challenge since they are all at the same level. Worth mocking up with balsa or something similar to see if you can get each switch to activate separately before you put a lot of time in the layout.

 

[kjhambrick]

<<snip>>

PS: that mag switch layout might be a bit of a challenge since they are all at the same level. Worth mocking up with balsa or something similar to see if you can get each switch to activate separately before you put a lot of time in the layout.

Adrian's new mag switch is polarized so maybe they could be orientated 180-degrees out of phase ?

New and improved Featherweight magnetic switch

Or something ?

EDIT: I did notice when testing and flying the Blue Raven on a Power Perch that my old steel threaded rods definitely interfered with the mag switch.

Maybe a magnetic shield of some sort would also work ?

-- kjh

 

[rocketace]

Tony,

In the past I have just threaded the ABS plastic for the 4-40. It works decently. If the treads start to strip, then I put some thick ABS slurry in the hole and re drill/tap. I have been doing it this way because my 38mm avbays have just not had the room for insert. This set up might, and it would be nice. I just need to find a short insert. Ill order some for this project and try them out! What ring terminals do you use when your not soldering to the mag switch?

I was definitely planning on testing, but its a good call to do that testing before I spend time designing the plastic mounts. My current idea is that the GPS will be turned on before its loaded on the rail. The mag switch will line up with the rail, but the GPS will be 180 to have as clear of a view as possible. This will leave the other 2 mag switches accessible when on the rail. Then, I will have a telescoping pole with a cradle+magent. This "cradle" will conform to the airframe so I can just slide it up the tube. My biggest concern is making sure the magnet is not too strong to turn them all on/off at once, but I have lots of different sized magnets I can play around with.


KJH,
Trying them out of phase could be interesting, but I think I want to stay away from any shielding. I would be worried about interfering with the GPS unit.
Also, I am playing around with the new mag switch and interesting note, the way they work off polarity is how his original mag switch worked! My first attempt will be to see if I can properly size the magnet to meet the goal. If that works, I shouldn't have to worry about any additional measures, but testing will tell.

 

[rocketace]

Another flight update!

I got to fly 2Testy on a J500G to a I205W. Overall the flight was almost perfect with 1 hiccup that I had to figure out. First off, the flight profile is described in the above post but basically I wanted to demonstrate delayed separation and ignition within specific parameters. The delayed ignition will be critical for my minimum diameter flight and the delayed separation is just because I think its more suspenseful. Here is the flight!


Here are some of the graphs from the sustainer. So much data to process….

This one is of the over all flight from the RavenV4. It matches very close with the Rocksim file


This is zoomed in to the apogee



Zooming in on the apogee deployment is fun. You can see the positive G shock with is the charge going off, then the 3 little negative G shocks followed by the larger negative G shock. The 3 little ones are my 3 different bundles of tape on the recovery harness and the last one is the harness fully extended. Ideally I want everything as evenly spread as possible and lower the better. So what this tells me is that my 3 bundles of tape need to be a bit stronger which will reduce that last shock load for this set up


Here is some BlueRaven data: Altitude and Tilt


Here is the same just zoomed in on the apogee


This is the comparison from the BlueRaven showing Tilt, Future tilt, and roll with the RTOM3 tilt. Sustainer ignition was at around 5 seconds.


So the 1 hiccup was a zipper in the booster, also it was noticeable watching it from the ground that it looked like the apogee ejection happened very shortly after booster separation. Here was the graph from the Raven. You can see that after the motor burn there is a negative G shock which was the booster separation charge then not much longer there was a slight pressure increase (altitude drop) followed by the positive Gs from apogee ejection, then chaos which caused a small zipper and ripped 2 shroud lines . Looking at the RavenV4 data I know it wasn’t the Raven, so it must have been my other altimeter in the booster, the MiniAltiDuo2. I really like the size and simplicity of the this altimeter but it seams it is not fully immune to pressure spikes. Im guessing the pressure spike happened due to the weird air flow caused by there not being a nose cone. I will have to replace it with a different altimeter, most likely another Raven…




Back to testing the magnetic switches, I found a good orientation and magnet that I can get very consistent results of turning on/off each switch without affecting the others. The below is what has worked the best for me. Note: This is for the new magnetic switch, as the older versions might behave different. I don't actually plan to have them packed this tight, I was just seeing if I could get consistent results with them as close as possible, even overlapping bit.



Last bit of update, The second carbon 54mm tube has been rolled. It had a few defects, but they are small enough that the fix should be quick.

 

[kjhambrick]

Jason --

Wow !

Beautiful flight and data but sorry about the zipper in your booster ... as you said, I also imagine a *-Raven will fix that issue ...

Thanks for the GREAT Video and your Mag Switch Test Results !

You showed a magic magnetic wand in post #46

Do you need to flip the magnet in the magic wand to turn off the Mag Switch(es) ?

If so did you come up with a way to flip the magnet in the wand ?

Or maybe it doesn't matter because you'll only want to turn off power after the flight where you can reach the Mag Switch ?

Thanks !

-- kjh( I need to come up with a BullsEye-Like Mag Switch Marker Decal for my Airframes -- maybe it is just about time for a StickerShock order )

 

[rocketace]

@kjhambrick ,
Thank! and its only 1.5" long. Some epoxy should fix it quickly. I did get some other damage. The bottom of the sustainer tube got pretty crispy from the I205. I will have to sand the bubbled epoxy and put a new layer before I can fly it as a sustainer again.

For the magnetic wand, I will either make it double sided or have a different heads for On/Off. I do want a way to turn them off on the pad just in case of a pad abort situation.

I like the sticker idea. In the past I usually use a sharpie to mark the spot, but this time that spot is going to be hard to see.

 

[manixFan]

Tony,

In the past I have just threaded the ABS plastic for the 4-40. It works decently. If the treads start to strip, then I put some thick ABS slurry in the hole and re drill/tap. I have been doing it this way because my 38mm avbays have just not had the room for insert. This set up might, and it would be nice. I just need to find a short insert. Ill order some for this project and try them out! What ring terminals do you use when your not soldering to the mag switch?

<...snipped for brevity...>

@rocketace – Great update! I really like seeing the data and your interpretation – especially the little peaks that correspond to the tape around the shock cord being broken. That's something I'll look for in the future. The on-board video is also fantastic.

Rereading the thread, I realized I never replied to your question – sorry about that! These are the ring terminals I use:

https://www.ferrulesdirect.com/products/rny1-32
And, just for reference, here are the inserts I've used – the ones in this link are very short:

https://www.amazon.com/gp/product/B07BH5X252/
(but unfortunately show as unavailable for now) I've also used these – they are longer but are available and less expensive:

https://www.amazon.com/gp/product/B08P1T5693/
I have a Hakko soldering station, so I bought these heat set insert tips for it:

https://www.amazon.com/gp/product/B09ZHLDPM2/
Looking forward to more cool updates! – and you need to start planning a trip to BALLS!


Tony

 

[kjhambrick]

Thanks for the link to Ferrules Direct, Tony.

Nice !

Lots of good goodies at that site !

I'll be ordering some DRNYB2-0.5 - Nylon Ring Terminal Brazed Seam 26-22 AWG for my mag switches where I've gone with #2-56 brass machine screws instead of #4-40 where the nuts are REALLY close together between Ground and Out ...

-- kjh

 

[rocketace]

Thanks Tony! And I’ll be getting some of those items to try out.

 

[rocketace]

Update: Sustainer AvBay

Tony finally convinced me to try the heat set inserts. Previously I was content with just threading into the plastic. I am very happy with them and even tried something a bit different.
I wanted to eliminate soldering to the Mag switch because it creates a week point if bent. I also did not want to use ring terminals due to their size. I tried soldering a wire lead directly to the heat set insert. It works! It was a bit of trial and error to find a temperature that would allow me to press the inert in easy and not melt the solder. I found on my 750F works well on my Hakko. I did some pull out tests and the wire its self broke before the solder joint or the insert pulling out.



Then I started messing around with how to best rout the wires. This is what I came up with to save space. Part of the channels are in the 3D model the rest is created by melting the plastic with a soldering tip.



The full electronics bay is split up in to 4 section. On the right is the batter mount, in the middle are 2 of the 3 mag switches, and on the left is altimeters / gps. The 4th part is the bulkhead that still has needs work and not pictured.


This is how it looks assembled so far. Its definitely over complicated and I am being too much of a perfectionist with minor details, but its fun to me



And here is what the model looks like so far. The grey rectangular block by the bulkhead is the pull switch for the ignitor shunt/disconnect. Looking at it like this make me ponder replacing it with a screw switch to save space. The same hole for what ever I use for the ignitor disconnect will also serve as the barro pressure hole.


Thats it for now, back to printing!

 

[OzHybrid]

Have you measured the temperature with everything running in there? Are you within the equipment's operating limits? Have you considered a cardboard shield on the launch tower to prevent the sun from heating the nosecone further on the launch day?

 

[rocketace]

Have you measured the temperature with everything running in there? Are you within the equipment's operating limits? Have you considered a cardboard shield on the launch tower to prevent the sun from heating the nosecone further on the launch day?

Great questions! I have not measured the temp and I’m not 100%sure what the operating limits are.

I do know that I have done similar in a 38mm nose cone and the temp at launch has never been more than 107F. And that was a 100 degree day in Texas. I am honestly not worried about it.

However, before when I was still thinking about including an onboard camera, I was very worried about it. That unit put out a LOT of heat. If I would have used that, I would have used cardboard/Mylar to shield the NC on the rail and done lots of testing. I was also looking into including a very small fan.

I do still need to test the GPS signal strength when it’s all finished to make sure I did not compromise it.

 

[StreuB1]

A white sheet of paper towel works extremely well as a heat shield from the sun and the rocket won't even notice it is there when you launch.

I have used this on my mobius camera mounts from Andrew several times in the past. I just tape a piece of paper towel on the side of the rocket so that the paper towel acts like an awning, effectively shielding the shroud. You could do something similar with the N/C in the tower.

Can be seen here in my 5" Super Jart at MMWP this spring.

It literally flutters away like half a second after this picture is shot.

 

[OzHybrid]

Great questions! I have not measured the temp and I’m not 100%sure what the operating limits are.

I do know that I have done similar in a 38mm nose cone and the temp at launch has never been more than 107F. And that was a 100 degree day in Texas. I am honestly not worried about it.

However, before when I was still thinking about including an onboard camera, I was very worried about it. That unit put out a LOT of heat. If I would have used that, I would have used cardboard/Mylar to shield the NC on the rail and done lots of testing. I was also looking into including a very small fan.

I do still need to test the GPS signal strength when it’s all finished to make sure I did not compromise it.

I'd say your batteries are the limiting factor. You could check temp with a thermistor, a resistor, a fixed voltage supply and a multimeter. Or just run it for a bit and use your wrist (baby bottle temp indication method) If you go owwwww, it's too hot.
Manufacturers of Li-ion battery usually gives the operating temperature of lithium -ion battery to range from 0 to 45°C for charging operations and -20 to 60°C for discharging operations The optimal temperature range for lithium -ion battery operation is between 15 to 35°C. (95F)

 

[rocketace]

I just tape a piece of paper towel on the side of the rocket so that the paper towel acts like an awning, effectively shielding the shroud.

That is a nice idea! I might try that in the future when I launch with an onboard camera. Thanks!

I'd say your batteries are the limiting factor.

Good point. I will take some measurements after everything is finished. I already make it a point to keep my rockets out of the sun until im heading out to the pad, I think this helps a lot.

 

[OzHybrid]

That is a nice idea! I might try that in the future when I launch with an onboard camera. Thanks!


Good point. I will take some measurements after everything is finished. I already make it a point to keep my rockets out of the sun until im heading out to the pad, I think this helps a lot.

Don't preheat the oven if you want to keep the ice cream cold.
With the hybrid, I used a damp towel over the whole tank area. Save some expensive gas in the pre-chill.

 

[StreuB1]

That is a nice idea! I might try that in the future when I launch with an onboard camera. Thanks!

I was suggesting it as an idea to help keep your electronics cool as they were in a confined space inside of a dark NC, as that was what was being talked about.....