Wildman Blackhawk 75

I have 3 out of the 4 sets of fillets complete. It seems like I've been using a lot less Rocketpoxy (by weight) than I have in the past.

This morning I decided to weigh all of the components and update my OpenRocket file. Everything seemed REALLY light. Too light. So I weighed a stack of quarters and they weigh about 1/5 of what they should. Crap! I guess my gram scale is toast. The funny thing is it was consistently off, so I could use it to measure out epoxy to a 50/50 ratio. I just can't use it to actually weigh anything.

I ordered a new 600g .1g accuracy scale from Amazon for $9 shipped. It's more the annoyance than the cost.

I picked up a 2" long 3/8-16 set screw, flat washer, lock washer, nut and lock nut to attach the forward closure to the retainer/hardpoint. I'm planning to use Red Locktite on the setscrew to the motor. I'm not sure that I need a lock washer and a backing lock nut. Is that overkill? Probably.

You should get a Distorted-Thread lock wire nut just for the hell of it, can never be too safe!

ChrisAttebery said:

I have 3 out of the 4 sets of fillets complete. It seems like I've been using a lot less Rocketpoxy (by weight) than I have in the past.

This morning I decided to weigh all of the components and update my OpenRocket file. Everything seemed REALLY light. Too light. So I weighed a stack of quarters and they weigh about 1/5 of what they should. Crap! I guess my gram scale is toast. The funny thing is it was consistently off, so I could use it to measure out epoxy to a 50/50 ratio. I just can't use it to actually weigh anything.

I ordered a new 600g .1g accuracy scale from Amazon for $9 shipped. It's more the annoyance than the cost.

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You may just need to calibrate the load cell, however on the low end of scales a decent calibration weight can easily cost as much or more than the scale.

There's no calibration on this scale. It's gotten worse since I posted. Now the weight is going down as the scale warms up. It's dead Jim.

I finally took the plunge and cut 16.5" off the booster this morning. The booster is 43.5" long. That leaves 7" for the recovery gear. I also epoxied the coupler ring for the retainer into the booster.

ChrisAttebery said:

I finally took the plunge and cut 16.5" off the booster this morning. The booster is 43.5" long. That leaves 7" for the recovery gear. I also epoxied the coupler ring for the retainer into the booster.

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Does that 7" NOT include the nose cone shoulder?

I'm in the beginning stages of a similar project and am currently scrutinizing your fin dimensions.

Yes, that's INCLUDING the NC shoulder. The Main is in the NC shoulder.

I finished the fillets on Thursday. This morning I wet sanded the entire booster with 220 grit. I'm trying to decide if I should clear coat it or leave it naked.

I epoxied the altimeter bay mounting ring into the NC coupler this afternoon. I've decided to attach the NC to the coupler with a pair of countersunk 4-40 screws and PEM nuts. That way I can access the inside of the bay from the top if I need to.

Motor retainer plate attached to the forward closure.


Fin fillets. Not my best work, but they're not too bad.


Paint? We don't need no stinking paint.


As it stands I need to finish the altimeter bay wiring, drill the holes for the shear pins and do some ground testing. I might even get that all done before I leave for XPRS.

That thing looks wicked fast sitting still! are you going to bring it to BALLS this year or just XPRS?

Thanks Slaak. I'm just going to XPRS this year. A bunch of people I know are going to XPRS so it's a chance to catch up with friends. I don't know too many people that attend BALLS.

slaak said:

That thing looks wicked fast sitting still! are you going to bring it to BALLS this year or just XPRS?

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I got the shear pin holes drilled and tapped. I decided to use 2x 2-56 nylon screws on both joints. This isn't a heavy rocket so that should be plenty.

I got the wiring done this morning. Next on my list are ejection charge testing, tower adjustment, and motor grain bonding.

Yesterday I assembled the grains for the M685. For anyone thinking about using this motor I HIGHLY recommend that you make sure that the grains will FREELY slide ALL THE WAY through the liner before you attempt to assemble it. I pushed each grain into the end of the liner before I started assembly and they were snug but slid in. Once I had the grain pairs epoxied together and started sliding them into the liner I found that they would go about 1.5 grains deep before they would start to get really hard to move. I used a board and a dead blow mallet to tap them into place. I wish I had peeled the grains a bit. It would have saved me a lot of cursing.

ChrisAttebery said:

Yesterday I assembled the grains for the M685. For anyone thinking about using this motor I HIGHLY recommend that you make sure that the grains will FREELY slide ALL THE WAY through the liner before you attempt to assemble it. I pushed each grain into the end of the liner before I started assembly and they were snug but slid in. Once I had the grain pairs epoxied together and started sliding them into the liner I found that they would go about 1.5 grains deep before they would start to get really hard to move. I used a board and a dead blow mallet to tap them into place. I wish I had peeled the grains a bit. It would have saved me a lot of cursing.

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Next time bond all the grain faces at once into the liner using R45 thinkened with micro-balloons or a long cure thick epoxy like Aeropoxy ES2609. Using a 5/8" dowel to keep things aligned. Like you said make sure they slide freely beforehand.

Aerotech's bond two at a time is the worst instruction you could give someone. Rarely are the grains square and even if they are - keeping them aligned requires a lot of babysitting. I've always been ripping casting tube off or sanding to get them to fit. Oh and cursing - lots of that...

Thanks for confirming that it wasn't just me. I wrapped a piece of 2" wide masking tape around each pair to keep them aligned. The ends were perfectly lined up when I put them in the liner. I bonded an M1780 with Glue All Max a couple months ago and it was easy by comparison. Everything slid in without a problem and the glue even seemed to help lubricate the surfaces. I was thinking that a low viscosity long cure epoxy would be better. Your method sounds solid too.

Kip_Daugirdas said:

Next time bond all the grain faces at once into the liner using R45 thinkened with micro-balloons or a long cure thick epoxy like Aeropoxy ES2609. Using a 5/8" dowel to keep things aligned. Like you said make sure they slide freely beforehand.

Aerotech's bond two at a time is the worst instruction you could give someone. Rarely are the grains square and even if they are - keeping them aligned requires a lot of babysitting. I've always been ripping casting tube off or sanding to get them to fit. Oh and cursing - lots of that...

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I also tested the ejection charges yesterday. I wound up with a .5g surgical tubing charge placed under the main. I used a 1g vinyl charge placed longitudinally next to the drogue. I modified Tony Alcocer's vinyl tubing charge design charge a little. I epoxied a 1/4" slice of dowel in the bottom, added a pair of 3/8" wide strips of duct tape crossed over each end and wrapped a 3/8" strip around the ends. This charge blew the contents completely out of both ends and shot the nose about 8'.

Not worried about the dowel going through your BT? I've seen a few centrifuge tube parts do that.

The charge is placed axially next to the drogue so it's pointed at the bulkheads not towards the side of the airframe. I could probably just use a plug of hot glue like Tony does.

Last night I built all of my ejection charges. All of my batteries are charged.

I'm thinking about completing assembling of the rocket tomorrow night. Since I've connected the NC to the coupler with screws I can access the electronics with the rocket completely assembled. I'll leave the hookup of the batteries and charges until the morning of the flight (Saturday).

I just posted a new thread and poll about prep work in the HPR forum. I'm curious what everyone has to say about it.

Good luck with the flight Chris.

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On Saturday morning I hooked up the charges and turned on the Telemetrum to get a GPS fix. After I got the fix I shut it down and loaded it into the tower. I turned the altimeters back on and saw that the TM was waiting for a lock. My experience in the past was that it had trouble getting lock in the tower but would get a lock once it went into coast phase. Unfortunately this time around it never got a GPS lock. I'm not sure what happened there.

The launch was clean and the boost straight. It turned to the West and ALTos announced the apogee as 37,789'. :eyepop: That was higher than I had simmed by a fair margin. I got data until the rocket was 200' off the ground but I never did get a GPS location.

On the ground the wind was blowing from the ENE so I headed WSW and drove until I hit the edge of the playa 5 miles away. I never saw it or got a blip on the radio. I drove back to camp and had a friend bring his RDF gear and we headed back out again. Again we never saw it or got a hint of a signal. We decided to head back to camp. As soon as we arrived someone let me know that the rocket had been found 1.5 miles East. Apparently the upper level winds were coming from the West.

My TAP let me know that he found the rocket and told me congratulations on my L3. We picked up the rocket and headed back to camp. Later that afternoon as I was cleaning the rocket up I found that one fin had cracked both fillets about 50% from the bottom and it was flexible.

Sunday morning we finally got together and agreed that the rocket was not flyable without a repair. So, I didn't get my L3. On to attempt #5.

The good news was that I won the AeroPAC Extreme Altitude M Class Competition. I broke the existing AeroPAC M record by 5,778'. It's still a ways off the 45,554' that Nic Lottering got with his TRA record but that was a full M. As a function of feet/Ns I have him beat. :wink:

It was a beautiful weekend and I had a great time. Maybe next year I'll try a full M.

ChrisAttebery said:

On Saturday morning I hooked up the charges and turned on the Telemetrum to get a GPS fix. After I got the fix I shut it down and loaded it into the tower. I turned the altimeters back on and saw that the TM was waiting for a lock. My experience in the past was that it had trouble getting lock in the tower but would get a lock once it went into coast phase. Unfortunately this time around it never got a GPS lock. I'm not sure what happened there.

The launch was clean and the boost straight. It turned to the West and ALTos announced the apogee as 37,789'. :eyepop: That was higher than I had simmed by a fair margin. I got data until the rocket was 200' off the ground but I never did get a GPS location.

On the ground the wind was blowing from the ENE so I headed WSW and drove until I hit the edge of the playa 5 miles away. I never saw it or got a blip on the radio. I drove back to camp and had a friend bring his RDF gear and we headed back out again. Again we never saw it or got a hint of a signal. We decided to head back to camp. As soon as we arrived someone let me know that the rocket had been found 1.5 miles East. Apparently the upper level winds were coming from the West.

My TAP let me know that he found the rocket and told me congratulations on my L3. We picked up the rocket and headed back to camp. Later that afternoon as I was cleaning the rocket up I found that one fin had cracked both fillets about 50% from the bottom and it was flexible.

Sunday morning we finally got together and agreed that the rocket was not flyable without a repair. So, I didn't get my L3. On to attempt #5.

The good news was that I won the AeroPAC Extreme Altitude M Class Competition. I broke the existing AeroPAC M record by 5,778'. It's still a ways off the 45,554' that Nic Lottering got with his TRA record but that was a full M. As a function of feet/Ns I have him beat. :wink:

It was a beautiful weekend and I had a great time. Maybe next year I'll try a full M.



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Congrats on the REALLY impressive flight. Sorry the cert didn't work out, but you had an awesome flight.

I was ready to reply CONGRATS Chris, then kept reading and though ahhhh dang it, I know you've worked really hard for this.
, however looking at that data that is still an amazing flight.
You are also approaching the most L3 motors purchased/flown by an L2 lol. You know I'm just funning you, we all know your skills here.

Something up with the name Chris, long burn M's and L3 attempts lately


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Maybe I'll have two records to my name.

Nick@JET said:

You are also approaching the most L3 motors purchased/flown by an L2 lol.

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Congrats on an outstanding flight Chris. So glad to read that it was found. I'm very much looking forward to your Mobius Mini video! Perhaps it would capture the reason for he fillet issue in the one fin. How much of the flight was visible from the ground?
Sorry I wasn't there to see it. (I'm in Charlotte NC right now.. on my way to Virginia.)

Nick@JET said:

Something up with the name Chris, long burn M's and L3 attempts lately

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At least I'm in good company. You'll get it next time, Chris. I applaud the bold attempts regardless of outcome. Cert what you want to fly, or what is the point.

Bummer about the fin, but congrats on an awesome flight!

Exactly!

Thanks Chris.

Cl(VII) said:

Cert what you want to fly, or what is the point.

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