First Attempt at a 38mm Minimum Diameter Launch!

[charrington]

Alright so heres the update on the flight yesterday:

First thing is that it was successful and I am now L2 certified! Really excited and can't wait to get started on my L3 sometime during the summer. The people at TRASD were extremely nice and helpful. So much so that my friend and I bought yearly memberships there and plan on making it our primary launch site. Couldn't recommend this prefecture enough.

So here is the flight video:


Here is a picture of the flight

 

[charrington]

Here is recovery:
View attachment IMG_1832-2.jpg
View attachment IMG_1834-2.jpgView attachment IMG_1835-2.jpgView attachment IMG_1837-2.jpg

The next thing is that it went straight as an arrow
apogee 14,184
Max velocity: 1393 fps / Mach 1.24
There is quite a difference between the velocity values from the featherweight and the rrc3. Featherweight gps shows 1393 fps on the excel sheet and missileworks shows 1846 fps.




All in all, a very fun and rewarding flight. This was definitely the most difficult build I have done to date, 38mm is not a lot to work with. Thank you all for your input during this and I cant wait to get started on my L3!


... Something else is in the works first though.

 

[charrington]

Oh and heres the mandatory prelaunch photo. Once again, thank you TRASD!

 

[charrington]

Shoulda recalled you've been to FAR with your university projects...
I greatly enjoyed your thread, it was interesting to see how you handled the same problems I encountered with ebay space constraints. One trick I discovered on the forum was "finger trap" for a robust, compact eye-bolt connection. View attachment 555676View attachment 555678

How did you manage to get the kevlar looped on to the eyebolt like that? I did something similar to get rid of the quicklinks but I just did some overhand knots. Yours looks like its has been attached by sewing.

 

[David_Stack]

How did you manage to get the kevlar looped on to the eyebolt like that? I did something similar to get rid of the quicklinks but I just did some overhand knots. Yours looks like its has been attached by sewing.

That is often referred to as a 'splice'. You can search here in the forum, and there are also 'how-to' videos on YouTube, etc. on how to terminate hollow braided kevlar in that way...

Nice certification flight!

 

[b.wieting]

How did you manage to get the kevlar looped on to the eyebolt like that? I did something similar to get rid of the quicklinks but I just did some overhand knots. Yours looks like its has been attached by sewing.

It's a "finger trap", taught in a post by Lowpuller.
https://www.rocketryforum.com/threads/finger-trap-technique.137003/
Slickest tip I've seen in a long time.

 

[b.wieting]

Here is recovery:
View attachment 555819
View attachment 555820View attachment 555821View attachment 555822

The next thing is that it went straight as an arrow
apogee 14,184
Max velocity: 1393 fps / Mach 1.24
There is quite a difference between the velocity values from the featherweight and the rrc3. Featherweight gps shows 1393 fps on the excel sheet and missileworks shows 1846 fps.
View attachment 555823

View attachment 555824

All in all, a very fun and rewarding flight. This was definitely the most difficult build I have done to date, 38mm is not a lot to work with. Thank you all for your input during this and I cant wait to get started on my L3!


... Something else is in the works first though.

Extraordinary! Ambitious cert project, impeccably executed!
(Mine was simple low & slow motor eject...).

 

[GrouchoDuke]

Gorgeous flight! Congrats on L2!!

 

[charrington]

Extraordinary! Ambitious cert project, impeccably executed!
(Mine was simple low & slow motor eject...).

Thank you I appreciate it a lot! It was well worth it, that J570 rips off the pad @AeroTech ! Nothing wrong with low and slow btw! Some of the best flights are ones that you see all the way to apogee. The anticipation as its arcing over at apogee and you are praying that those chutes deploy… especially when you get big roaring motors in super large and heavy rockets. They have a time and place too!

 

[charrington]

Gorgeous flight! Congrats on L2!!

Thank you! You helped a lot during this build and I appreciate it very much.

 

[GrouchoDuke]

Thank you! You helped a lot during this build and I appreciate it very much.

It's great to see you got your photo with the rocket - gotta have that! Enjoy L2!

 

[AeroTech]

Thank you I appreciate it a lot! It was well worth it, that J570 rips off the pad @AeroTech ! Nothing wrong with low and slow btw! Some of the best flights are ones that you see all the way to apogee. The anticipation as its arcing over at apogee and you are praying that those chutes deploy… especially when you get big roaring motors in super large and heavy rockets. They have a time and place too!

Great job!!

 

[Buckeye]

Very nice build and flight.

Here is recovery:
View attachment 555819
View attachment 555820View attachment 555821View attachment 555822

The next thing is that it went straight as an arrow
apogee 14,184
Max velocity: 1393 fps / Mach 1.24
There is quite a difference between the velocity values from the featherweight and the rrc3. Featherweight gps shows 1393 fps on the excel sheet and missileworks shows 1846 fps.

Both the RRC3 and FW are differentiating position data to get velocity, which is not a very accurate approach. Integrating accelerometer data to get velocity is a better measurement but still not perfect. The best estimate of max velocity is actually the numerical simulation.

Did the FW GPS maintain lock for the whole flight? If it is missing data, you may not be comparing the same flight time as the RRC3. Also, the RRC3 samples at 20 Hz, the FW at 10 Hz. The GPS is excellent at measuring apogee when the velocity is near zero, but probably not at Mach 1.4.

 

[charrington]

Very nice build and flight.



Both the RRC3 and FW are differentiating position data to get velocity, which is not a very accurate approach. Integrating accelerometer data to get velocity is a better measurement but still not perfect. The best estimate of max velocity is actually the numerical simulation.

Did the FW GPS maintain lock for the whole flight? If it is missing data, you may not be comparing the same flight time as the RRC3. Also, the RRC3 samples at 20 Hz, the FW at 10 Hz. The GPS is excellent at measuring apogee when the velocity is near zero, but probably not at Mach 1.4.

After looking over my sim and adjusting it I believe you are correct and the sim is more accurate for velocity. I have my OR pretty close in apogee to what the FW suggests and its showing a much higher velocity than the FW. The FW gps did lose lock for a few data lines during the boost.