Wildman Blackhawk 75

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Chris's rocket as I found it..

36500309483_5975fea0fc_z.jpg


Tony
 
You can CLEARLY see that nothing is cracked in that photo. The damage must’ve happened later. L3 COMPLETE!! ;)
 
Do you have any idea what caused the crack, like ground impact or something else?

Heckuva consolation prize though. Well done!
 
The main velocity of 44 ft/s looks way too high for a properly inflated 48" Fruity Chutes Iris. However, it is laying there perfectly in the pic Tony uploaded. Was there any evidence of tangled lines?
 
no tangled lines. It was picture perfect. Hence me taking a photo.

I did pack the chute into the body tube ..to keep it from taking off..even though there was no wind at the time.

Tony
 
Best "failed" L3 cert flight ever! Impressive build and flight sir, thanks again for taking the time to share the details. :)
 
BTW: From the video it appears that at least one of my primary charges was undersized. If you listen you can hear a pop at apogee, silence, and then another pop and the chute came out. From looking at the video and data from the Telemetrum I'm not sure if the main came out at 1200' and just took a while to fully deploy or if the backup charge was needed there too. Gene at Fruity Chutes advised me to use a slider ring on the main chute in case of a high speed deployment and that may have caused it to take a while to fully deploy.

I had ground tested and then increased my primary charges by about 20%. The backups were another 50% larger.
 
The main had a slider ring on it to protect it from a high speed deployment. I'm not sure if the ring caused it to take a while to deploy or if the the primary charge wasn't strong enough to deploy the main. I think the descent rate on the data chart is the average from deployment to landing. The data suggests that the rocket was slowing down during most of that period.

The main velocity of 44 ft/s looks way too high for a properly inflated 48" Fruity Chutes Iris. However, it is laying there perfectly in the pic Tony uploaded. Was there any evidence of tangled lines?
 
BTW: From the video it appears that at least one of my primary charges was undersized. If you listen you can hear a pop at apogee, silence, and then another pop and the chute came out. From looking at the video and data from the Telemetrum I'm not sure if the main came out at 1200' and just took a while to fully deploy or if the backup charge was needed there too. Gene at Fruity Chutes advised me to use a slider ring on the main chute in case of a high speed deployment and that may have caused it to take a while to fully deploy.

I had ground tested and then increased my primary charges by about 20%. The backups were another 50% larger.

Hi Chris, great video and congrats on that flight. It sounds like the perfect flight for my likes, good end result but some anomalies to dig into. I would agree with your first observation that the main apogee charge popped but failed to separate. Possibly a bit more ground testing would confirm that. As far as the slider ring, I also just started using the slider ring on my Iris Ultras coming out of my D-Bag, but I only have one flight under my belt with this config. I will have to take a closer look at the data to see if it shows any retard affect that the slider ring had on full deployment. One thing I did catch on my on-board video was a few frames of the main deployment where you can see the ring sliding down the shroud lines.
 
Hi Chris, great video and congrats on that flight. It sounds like the perfect flight for my likes, good end result but some anomalies to dig into. I would agree with your first observation that the main apogee charge popped but failed to separate. Possibly a bit more ground testing would confirm that. As far as the slider ring, I also just started using the slider ring on my Iris Ultras coming out of my D-Bag, but I only have one flight under my belt with this config. I will have to take a closer look at the data to see if it shows any retard affect that the slider ring had on full deployment. One thing I did catch on my on-board video was a few frames of the main deployment where you can see the ring sliding down the shroud lines.

I have to ask why a deployment bag and the ring?The bag should force the lines to be straight, which should negate the need for the ring.


Sent from my iPhone using Rocketry Forum
 
In this case it had a parachute liner not a full bag. The liner is basically an open topped cylinder with a split down one side. The liner was attached at the shock cord/shroud line connection point.

The ring is there to prevent a shock opening during a high speed deployment.
 
The bag forces the lines straight, the ring gradualizes(?) the opening. I think.
Correct.

The purpose of the ring is to slow the chute from inflating fully, it is more of a gradual opening vs. the sudden stress of a pop.

The purpose of the D-bag is to control the deployment. So lines are pulled out first, and away from the rocket and chute is last.

Generally it is much more controlled and also helps to mitigate against an inverted deployment.

Sent from my ONEPLUS A3000 using Rocketry Forum mobile app
 
The main had a slider ring on it to protect it from a high speed deployment. I'm not sure if the ring caused it to take a while to deploy or if the the primary charge wasn't strong enough to deploy the main. I think the descent rate on the data chart is the average from deployment to landing. The data suggests that the rocket was slowing down during most of that period.

Gotcha. If you zoom in on the drogue portion of the descent you should see the point at which the parachute is fully opened, i.e. ring stops sliding. Up to that point you should see the descent rate decreasing until it is fully inflated at which point the descent rate should stabilize.
 
I took a close look at the video with DashWare so I could see the altitude. The chute came out at around 1200'. I found a couple frames that had the cap for the bay in them. I also saw one frame where the chute was deployed but still wrapped in the parachute liner. It took 300-400' to fully deploy. The landing was at ~15mph so I guess I just need to improve the strength of my fin attachment.
 
I took a close look at the video with DashWare so I could see the altitude. The chute came out at around 1200'. I found a couple frames that had the cap for the bay in them. I also saw one frame where the chute was deployed but still wrapped in the parachute liner. It took 300-400' to fully deploy. The landing was at ~15mph so I guess I just need to improve the strength of my fin attachment.

Chris, how were the fins attached?


Sent from my iPhone using Rocketry Forum
 
I took a close look at the video with DashWare so I could see the altitude. The chute came out at around 1200'. I found a couple frames that had the cap for the bay in them. I also saw one frame where the chute was deployed but still wrapped in the parachute liner. It took 300-400' to fully deploy. The landing was at ~15mph so I guess I just need to improve the strength of my fin attachment.

Man, that is some unforgiving ground to knock one of those fins loose at 15 mph (22 fps). Bad luck, but you'll get it. Maybe 1 layer of t2t after the fin is back on?
 
I used a 1" diameter tool to create the fillets. After the first couple pairs I considered using a 1.25" tool. I wish I had now.

I don't think T2T is necessary to handle the flight stress. I also thought about adding a strip of CF over the fillets and partially up the fin and body tube, maybe 1/2" overlap on each side.

Man, that is some unforgiving ground to knock one of those fins loose at 15 mph (22 fps). Bad luck, but you'll get it. Maybe 1 layer of t2t after the fin is back on?
 
I used a 1" diameter tool to create the fillets. After the first couple pairs I considered using a 1.25" tool. I wish I had now.

I don't think T2T is necessary to handle the flight stress. I also thought about adding a strip of CF over the fillets and partially up the fin and body tube, maybe 1/2" overlap on each side.

Yes, I meant as landing insurance. You are clearly good on the flight stress. Your proposal of 1/2" overlap CF would do the same thing as far as landing damage prevention...just something to tie everything together. I was just thinking that as it wouldn't require replacement of the other fillets. There are a ton of ways to sure it up, and I'm still surprised that what you did wasn't sufficient. That stuff me be like landing on concrete.
 
Last edited:
Chris, if I understand how you rigged the parachute liner, there was nothing to positively extract the parachute from the liner as the shock cord was being pulled out of...wherever it is pulled from with head-end deployment. (I've not figured that out yet but it is next on my list.) The first time I used the Fruity Chutes liner, I had a significant delay (4 seconds) between the deployment event and the time the main set. Same as you. And it was pretty unnerving because we were watching as the main event happened right on schedule, but the rocket fell from 700 feet to around 350 before the main inflated. An unnerving 4 seconds, to say the least.

What I've done since then (two successful deployments including my cert flight on Friday) is to secure the tether of the liner so the shock cord, low enough that it stops while the rest of the shock cord and NC are still moving. This extracts the parachute from the liner with certainty. A wrap of duct tape is enough to hold the tether fast to the shock cord.

The liner is a nice way to protect the parachute and most of the nylon shock cord, but I found that it's not inherently unstable like a burrito is. My burritos want to unroll on the table...so dumping the main when it's shot out of a tube is pretty much gonna happen every time. With the liner, that's a bit more random. The chute will probably come out sometime after the main deployment...but "probably" is very bad, and "sometime after" is nearly as bad. Taping the liner to a spot low on the shock cord seems to have fixed the problem for me.

Sorry to hear about the outcome of that flight. You were explaining it to me on the playa right as my last rocket of the day was going off, and I apologize that my attention was drifting away...I think you were telling me that the telemetry said it was down, but I'm not sure if you had found it yet. Sounds like you were on a bit of an emotional roller coaster out there.

Any of us can build a 3FNC kit, and maybe add a bit of reinforcement..my cert flight on Friday afternoon was not really a big deal, just a bigger rocket and motor, and a second altimeter. Your stuff is totally bad-ass, so just keep pushing the envelope. Can't wait to see what you come up with next!

-Reed
 
Hi Reed,

You're right, there was nothing to ensure that the parachute would be pulled from the liner. I deployed my chute at 1200' to give it extra time to extract itself from the liner. I'll take another look at it to see if I can attach it in a manner that will help pull it free of the parachute. The one I use on my Punisher is attached to the top of the chute so that just the drag of the air flowing over the liner will pull it free.

I understand being distracted at the launch. Believe me, I lost track of a few names over the weekend. I never did get a good GPS packet from the Telemetrum. I think I understand why, but I'm not very happy about it. I could have fired up the altimeter with the NC clear of the tower and lowered the rocket into the tower after it got a GPS lock, but it makes me really nervous to be bumping the airframe around with live charges aboard.

Saturday was definitely a emotional roller coaster. I had the high of a clean flight, followed by the low of losing track of the rocket, to finding out it was found intact and thinking I had my L3 wrapped up, to finding the fin cracked loose.

I'm not going to stop doing what I do, but I'm hoping that I've learned enough lessons over these last few flights to cover me for a while.

See you at lunch,



Chris
 
I kept thinking about why my primary charges didn't appear to be strong enough. I decided to load the video in DashWare and verify where the events actually happened. I found two frames that disprove my earlier thoughts.

First, I found a frame after apogee that clearly shows the intact backup charge.
Black Falcon 75 Apogee Charge.jpg

Then I found a frame that clearly shows that the main was ejected at ~1300. The backup was set for 800'.
Black Falcon 75 Main Charge.jpg

Clearly the primary charges worked. I'm not sure what the clunking noise followed by 6 seconds of silence was at apogee. I'm pretty sure I understand why the main took so long to fully deploy.
 
Back
Top