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Date:  30th October 2010
Location: Doonside, NSW, Australia
Conditions:  Warm 29C, clear 5-10km/h wind.
Team Members at Event: PK and GK

Launch Day Report

We wanted to fly the Acceleron V booster again, since it was repaired and we hadn't flown it for quiet a while. The sustainer has had a couple of modifications made to it, such as remote arming, smaller fins, and the top 1.25L bottle was replaced with a 2.1L spliced pair. As we arrived at the launch site around 8:30 am, there was early fog but that cleared by the time we had the launcher ready. The weather was great for launching though there was a slight breeze in the direction of the rocket eating trees.

• We set up the rocket on the launch pad, and went through the checklist. When I turned on the back-up flight computer I noticed it had switched into the configure mode. This is normal behaviour when the ARM button is pressed. It looked like there must have been a short somewhere. As part of the Acceleron V servicing we did a couple of weeks earlier we added a set of contacts in parallel with the ARM button to be able to arm it remotely. (To prevent false triggers during pressurisation) It must have been this connection that was shorting out. To check it properly would have needed us to pull the rocket apart and at least 30-40 minutes work. So we cut a larger access hole in the fairing and unscrewed one side of the flight computer and poked a stick underneath the PCB to try to move the wires going to the set of contacts. Thankfully that fixed the problem, but we weren't sure if it would crop up again. In the two launches we did, the problem didn't come back, but I'll need to go back and fix it properly.

• Other than that hiccup, the rest of the tasks on the checklist went smoothly. The booster still used 2.5L of water in each segment, but we added an extra 200mL to the sustainer for a total of 1.5L of water/foam mix. We pressurised both the booster and sustainer to 120psi. The launch was really good and mostly vertical. The sustainer released right on cue or perhaps a little late but vertical, and then powered to 864 feet (263m) on foam. The foam makes it really easy to track the rocket on its way up.  This was our new personal highest altitude to date with the last one at 810 feet.

• Both the booster and sustainer opened their parachutes right on cue and landed reasonably close to the pad. The booster slightly cracked the balsa ring brace, but it looks like it was an older break from the explosion last year. A bit of tape fixed it right up ready for the next launch. We downloaded all the data first from the two on-board cameras and the two on-board altimeters, in case we lost or damaged the rocket on the next flight and we didn't want to loose the data from the first flight. Both cameras and altimeters captured good data.

Flight #1

Booster altitude plot	Sustainer altitude plot

• Within an hour we had set the rocket up again on the pad, but because the wind had shifted around and was now going directly for the trees we angled the launcher slightly so the rocket would fly away from the trees.

• We pressurised the rocket to 120psi again, and launched. The rocket angled over slightly in the intended direction, but the flight was nearly identical to the first. The staging was very clean again and the sustainer powered it's way up to 829 feet (252m). This was partially due to the angle and so did not go completely vertical. Even though it travelled lower, it still flew for 5 seconds longer. I think this was our longest duration flight at 68.6 seconds.

• Both booster and sustainer landed well. In the post landing picture and video you can see that the booster looks damaged. It is actually only twisted and is a result of the boosters design to allow it to flex. Untwisting it aligns everything up again. The slow-mo video also shows the condensed fog coming out of the nozzles just after burnout and prior to staging. We hadn't seen that before in our launches.

• Again both altimeters and cameras recorded good data. The new battery on the FlyCamOne2 is working well and we haven't had any more early  shut downs.

• Many thanks also goes to David, Craig and Phil for helping us with the remote arming, launching and camera operation.

Flight #2

Booster altitude plot	Sustainer altitude plot

 

Flight computer settings:

V1.6			V1.6			V1.6
Primary			Secondary			Sustainer
0.	0		0.	0		0.	0
1.	0		1.	1		1.	8
2.	1	0.1 secs	2.	8	1.8 secs	2.	2	8.3 secs
3.	0		3.	0		3.	0
4.	0		4.	0		4.	0
5.	1	0.1 secs	5.	1	0.1 secs	5.	1	0.1 sec
6.	0		6.	0		6.	0
7.	V		7.	R		7.	V
8.	7	1.12 secs	8.	7	1.12 secs	8.	F	2.4 secs
9.	U		9.	V		9.	0
A.	0		A.	0		A.	V
B.	F	2.4 secs	B.	F	2.4 secs	B.	F	2.4 secs
C.	0	sound OFF	C.	0	sound OFF	C.	2	Sound ON
D.	0		D.	0		D.	4
E.	0		E.	0		E.	5

Polaron G2 - Progress Update

We have been posting day to day progress on our blog of the Polaron G2 development, but I'll do a summary here of all the updates since day 96.

Spliced Quads

We have been reinforcing and testing the spliced quads shown in the previous update. We now have 5 spliced quads made and tested to 270psi. Two more are curing and need to be sanded before testing. We now have enough of the spliced quads for phase 1 of the development. So far we are happy with how these are turning out, but we won't know for sure until they are used on real rockets.

	4 x 2L bottles spliced together with Sikaflex 11FC
	200gsm glass cloth cut to the pattern.
	Wrapping glass fibers into grooves
	Wrapping cloth on to the quad
	We use West Systems epoxy as the resin.
	The quads are then placed on a rotisserie to cure the epoxy evenly and without runs.
	The quad is then sanded to clean up any uneven edges.
	Then it is hydro tested to 270psi inside an old scuba cylinder with the bottom cut off to contain noise and any shrapnel.
	Spliced quads ready for assembly.
	These are joined using tornado couplings with a couple of o-rings to seal them.
	Phase 3 main stage assembled with a representative sustainer on top. Now where did I put that ladder?

Nosecone

We have spent quite a bit of time in the last month making up a nosecone plug so that we can make fiberglass nosecones with the proper shape rather than just tops of bottles. A big thanks goes to the guys on Australian Rocketry's forum and the Yahoo water rocket forum who gave us a lot of great tips for making the plug and nosecone. It's been a very good learning experience.

We made the plug from 10 layers of 19mm MDF. These were first rough cut with a circular table saw, and then individually machined on the lathe to the correct dimensions. These were then glued together with PVA glue, and the whole shape was sanded smooth. We then applied a couple of layers of epoxy to seal the surface, and used putty to seal up any imperfections. We then sprayed the whole nosecone with spray putty and sanded it all smooth again.

Next we applied a coat of Wattyl Estapol 7008 2-pac paint to the plug which left it nice and shiny. We then applied 8 layers of mould release wax and polished it again.

We used 2 layers of 200gsm glass cloth for the nosecone. Because we had trouble removing the nosecone from the plug, we had to cut it length ways. Though it came away from the plug cleanly.

This cut was then patched from the inside and the whole nosecone was covered with a layer of micro-balloon / epoxy mix to fill in any imperfections. We glued half a ping-pong ball into the end of the nosecone and covered it with more epoxy. The whole nosecone was then sanded again and is now ready for spray paining. This first nosecone weighs 70 grams, but we will use the 85gsm cloth on the second test nosecone.

	19mm MDF roughly cut to shape.
	These are then machined individually to the exact dimensions.
	A nice mess is left to clean up. :(
	All 10 disks ready for gluing
	They are glued together with PVA glue.
	The nosecone plug ready for sanding. Sanding is done on the lathe.
	The plug was then coated with a couple of layers of epoxy, and sprayed with spray putty and sanded smooth again.
	We then brushed on Wattyl Estapol 7008 2 pac clear paint to make the surface nice and hard.
	We placed it again on the rotisserie to keep an even coat on the plug.
	We then applied 8 coats of release wax to the surface.
	200gsm glass cloth was then cut out to give us 2 complete layers
	Applying the epoxy
	Nosecone removed from the plug.
	We had a bit of trouble removing it so we had to split it.
	The cut was then patched from the inside and the whole nosecone was coated with a paste made from microballoons and epoxy to fill in all the cracks.
	The nosetip was then added and sanded smooth. Here it is after the first coat of undercoat. Currently the nosecone weighs 70 grams.
	A couple of coats of primer and a further two coats of gloss enamel.

Parachute Deployment Mechanism

We have been considering what would be the preferred  parachute deployment mechanism to use in phase 1, and currently it looks like we are going to go with an in-line design similar to the one we developed earlier. This will allow us to utilize the space in the new nosecone, and make the payload bay a lot shorter for the electronics. The camera and altimeter will be located between the top two spliced-quads, to offer some protection in the event of a hard landing.

In phase 2 we are likely to use a dual-deploy mechanism as we expect higher altitudes and don't want the rocket to drift too far. The main parachute will be deployed the same way as described above, but the drogue chute will be located mid body of the rocket between the spliced quads. We'll use the MAD to deploy the drogue after apogee, since it will be much more difficult to predict how the rocket will perform. This should bring the rocket down horizontal for the first half of the descent, then the main will deploy from the nosecone.

Fins

We have also been investigating different fin materials to use with the G2 rocket. We compared 3 different ones:

• Regular 4mm 3-ply plywood - This fin is very tough, but the main drawback is its weight. At 74 grams it is the heaviest and thickness is 4.2mm.
• Balsa Sandwich - Made out of two 1.5mm sheets of balsa wood glued together at 90 degrees to each other with PVA glue. One layer of 200gsm fiberglass on either side. Epoxy resin was used for this. The fin is quite tough and weighed in at 43 grams. The thickness is 3.9mm but the main drawback is the amount of work involved to do this and the higher cost.
• Corflute - This weighed in at 25 grams, but has a thickness of 5mm. It is quite tough, and has a good finish, but the main drawback is that it is made from polypropylene and hence harder to glue and paint. The leading and trailing edges are made from plastic straws.

We have decided to go with the Corflute fins on the first trial flights to see if they can hold up to the higher speeds and loads. If it turns out we can't use them, then we would switch to the Balsa Sandwich. We have the 3 fins now made and they are awaiting to be attached to the removable fin can.

	Three fins being tested. Left to right: Corflute, balsa sandwich and plywood.
	Corflute fins cut out using a cardboard template.
	Cut Corflute has flat edges.
	In order to embed the leading and trailing edges we use a Dremmel tool with a round sanding bit to cut a channel.
	We then tape on plastic straws into the channel.
	3 fins ready to be mounted to the fin can.

Flight Details