Icarus I: a 38mm minimum diameter build

raptor22 said:

Just to update, things are still moving steadily along.

We got a chance to cast the propellant recently with our propellant mentor, but there are some complications with the mandrels sticking. He has some tricks to get them un-stuck, so stay tuned for details on that process. We ended up going with a pretty aggressive catalyzed propellant that is simulating a delivered ISP of 247 in BurnSim for our motor geometry.

It will be very excited to see how this motor will perform under real-world conditions. We will have enough propellant for two reloads, so we should have an opportunity to post the actual delivered thrust curve after static testing.

Unfortunately, I didn't take any photos of the casting process, so I don't have any visuals to post.

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That's probably better that you didn't as the moderators might prefer that motor making "stuff" be confined to the restricted "Research" forum. I suspect mentioning motor status wouldn't irk any of them in the public forum but details might raise
some eyebrows if placed here. Perhaps one of them would comment to clarify as I am not a moderator. Nice project. You might want to run your antenna through a stiff plastic stent so it lessens the risk of the wire antenna getting squished, lowering your effective range. I run a Beeline GPS in the ebay of a Wildman Jr and the wire antenna projects into the
main chute bay forward through a form fit hole in the forward bulkhead. I use the cardboard tube that the HPR wired igniters come in with AT loads and wrap it in duct tape for flash protection. I use clay to affix the "stent" to the forward bulkhead
and it keeps the antenna from getting squished. Kurt Savegnago

I have some updates to this project. We have been getting a lot done over Christmas break, and have set a firm launch date of February 6th.

The propellant has been successfully removed from the casting apparatus, and our mentor says they appear finely cast with no voids. The EX motor work was, in many ways, the heart of this project. So, it feels awesome to have that done and we can't wait to fire it up.

Construction and wiring of the altimeter sled is complete.



Fins have been cut and beveled to a nice leading and trailing edge. They are cut from a .125" sheet of high-grade canvas phenolic I had lying around. We rounded the contour of the "bevels" out where they meet the body of the fin to prevent airflow separation during the subsonic part of the flight, hopefully decreasing drag. This probably increases the risk of coning a bit, because its harder to keep the fins perfectly symmetrical, but I used to make a lot of balsa gliders and have a pretty decent eye for these things. So, I think it will be a net benefit.



Here is one of our team members drawing out the fin slots using a mini-mill on campus. We originally planned on simply milling the slots, but our smallest mill bit size is 1/4". So, we chucked up a nice roller-ball pin and used the mill to draw perfectly straight lines we cut out manually with a dremel tool.



Aaaannd here is the obligatory dry-fit photo.

ksaves2 said:

That's probably better that you didn't as the moderators might prefer that motor making "stuff" be confined to the restricted "Research" forum. I suspect mentioning motor status wouldn't irk any of them in the public forum but details might raise some eyebrows if placed here. Perhaps one of them would comment to clarify as I am not a moderator. Nice project. You might want to run your antenna through a stiff plastic stent so it lessens the risk of the wire antenna getting squished, lowering your effective range. I run a Beeline GPS in the ebay of a Wildman Jr and the wire antenna projects into the main chute bay forward through a form fit hole in the forward bulkhead. I use the cardboard tube that the HPR wired igniters come in with AT loads and wrap it in duct tape for flash protection. I use clay to affix the "stent" to the forward bulkhead
and it keeps the antenna from getting squished. Kurt Savegnago

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Kurt, thanks for the comments and that is essentially what we plan to do. Bring the antenna into the parachute bay with a stent. I won't be mentioning any motor details that could be used to manufacture motors, but thank you for the warning.

Here is a little teaser regarding our next project, as well. A 29 mm diameter boosted dart, powered by an Aerotek L2200G.



We will be starting construction shortly after the launch of Icarus 1. It is simulated to remain in the transonic realm or faster for a solid 21 seconds, which should be quite exciting.

We are extremely excited for the launch this Saturday! Preparations are at full steam.

Fins are mounted and 'glassed, recovery testing is complete, and our ground station is doing a flawless job with the BigRedBee tracker.

Paint is going on today, and then Icarus 1 will be pretty much ready to go.

raptor22 said:

Here is a little teaser regarding our next project, as well. A 29 mm diameter boosted dart, powered by an Aerotek L2200G.


We will be starting construction shortly after the launch of Icarus 1. It is simulated to remain in the transonic realm or faster for a solid 21 seconds, which should be quite exciting.

Click to expand...

If it spends an appreciable amount of time supersonic, don't expect any stick-on labels or accoutrements to survive the heating.

Once the button is pushed, it always seems like it takes forever before that first position packet shows up. Must be the adrenaline rush that makes it seem so long. Have a good flight. Kurt

ksaves2 said:

If it spends an appreciable amount of time supersonic, don't expect any stick-on labels or accoutrements to survive the heating.

Once the button is pushed, it always seems like it takes forever before that first position packet shows up. Must be the adrenaline rush that makes it seem so long. Have a good flight. Kurt

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Don't worry, the dart itself will be bare metal. We are firing from a private launch site with a lot of safety precautions, so have the luxury of turning the body and tailcone from a solid steel rod.

Thanks for the well wishes. I am very nervous and excited to see how it does this weekend.

raptor22 said:

Don't worry, the dart itself will be bare metal. We are firing from a private launch site with a lot of safety precautions, so have the luxury of turning the body and tailcone from a solid steel rod.

Thanks for the well wishes. I am very nervous and excited to see how it does this weekend.

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Just thinking about this. Have you done any dispersal/splash patterning for the dart? That coming in clean would punch through just about anything. You want to know where it is going to make sure all is clear, and not just for an optimal flight.

markkoelsch said:

Just thinking about this. Have you done any dispersal/splash patterning for the dart? That coming in clean would punch through just about anything. You want to know where it is going to make sure all is clear, and not just for an optimal flight.

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I think the Icarus has a recovery system and the dart is for a future project. I suspect that a dispersal pattern would probably be wise no matter where one is launching from. Question: If the dart has no recovery system and is all metal, how can anyone
track it to know how high it went? (Unless of course radar is being used from the ground.) Kurt

Both rockets will have a recovery system, we definitely won't be doing an intentional ballistic recovery for either project.

Icarus 1 is your standard drogueless dual deploy setup.

The dart project (Icarus 2) will have a hollow cavity milled out of it, containing a fiberglass avionics canister, shock chords, parachutes, etc. At apogee, it will eject the canister and start relaying data to the ground station. Really only the nose and tailcone sections would be left as solid metal.

I would agree that dispersal patterns are a wise plan of action. The SDSU Rocket Project has a rocksim pro license, and we will likely use that to do dispersal patterning.

We threw some paint on last night, so here an update of how the project is looking.

We just got back from the test site late last night. Icarus 1 leapt off the pad lightning-fast with no signs of coning whatsoever. The boost was kicked about 15 degrees off vertical, possibly due to interaction with the fly-away rail guide, but was picture perfect afterwards to achieve a maximum altitude of 12,247'.


There were some hiccups with the flight that we will go over in a complete writeup sometime soon, but overall we consider it a big success. The team learned an enormous amount, the experimental motor performed flawlessly, and we achieved complete recovery of all important flight components and data.


Thank you to our sponsors: BigRedBee, CrownAir, AeroRocket, and K2Engineering. We had a long walk for recovery, so the BigRedBee GPS was a huge boon.
We also owe a huge thanks to our mentor Ron, and to Friends of Amateur Rocketry for supplying such an amazing site to launch from.

*applause*

Coulda kissed it good-bye without the tracker huh? Download the .kml file for review. That's always neat. Kurt

Thanks for the comments, folks.

We almost certainly wouldn't have found it without the BRB tracker. It was moving fast enough that the second we had burnout it disappeared from sight. We started getting packets near apogee and tracked it as it arced up over the neighboring RRS test facility and landed in depression about half a mile away. With the distance, brush, and late hour in the day our chances would have been slim but with the tracking gear we just walked right to it.

Rick Maschek got a great photo as it was leaving the pad:



Video of the launch. You can see a bit of wobble from an impact with the rail guide on the way up:

https://youtu.be/ZrFvOR8uCwc