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- Oct 5, 2011
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Congrats on your level 2 flight! Good looking rocket. I love a sparky motor.
Kevin - a big congrats on your L2!! I remember that nervousness & jitters like it was yesterday (cause it almost was, 6 months ago), you did a great job. Also, a very big thank you for a great build thread, I've just ordered my first all-glass kit (Madcow Frenzy XL 3"), and I'll definitely be rereading your posts for tips as I go... This is truly the value of TRF, sharing information to aide in the success of many... Again, thanks for a great thread!! :handshake:
A case of congratulations to us both! It's a great feeling, isn't it?
Congrats Kevin! Love that nervous feeling during the count down then again editing for the main!
That's really awesome! Beautiful rocket
just SPECTACULAR!!!! way to go!!!!
Thank you very much. Honestly on the way up is the fin alignment. Get them on dead straight; and they pretty much fly dead straight. https://www.payloadbay.com/index.php?page=Tools&action=FINGUIDES Thankfully the payloadbay.com One the way down, the drogue makes the roll; but the main, sized a tad over; seems to really make it float. Maybe it's the type: Loc Angel, more likely luck. I know my Level 1 Torrent was pretty straight on it's maiden flight; but I eyeballed the fins.Great on-board video! No nausea-inducing roll, like my videos. What is the key to minimizing roll?
You're going to have to try harder than that. I just got my L2 today with the Torrent on a J270, going to 4219 feet. Haven't downloaded the data, so I don't have a speed, but OR estimated 715 fps. Of course, OR underestimated altitude by 500' so I'm guessing the speed was a bit higher. That Torrent is a great bird.After the Level-2, we decided to try to rip the fins off last month's Level-1 bird, the Torret, by shoving an I540 in it an hitting 3489ft and the stratologger said 740fps for velocity. It screamed off the pad. SO COOL!
You're going to have to try harder than that. I just got my L2 today with the Torrent on a J270, going to 4219 feet. Haven't downloaded the data, so I don't have a speed, but OR estimated 715 fps. Of course, OR underestimated altitude by 500' so I'm guessing the speed was a bit higher. That Torrent is a great bird.
While I'm on it, I had someone mention at the club event that when flying L-2 and above, you should also put shear pins in the aft portion of the e-bay/body tube like I do with the nosecone. I hadn't heard or read that before; and am curious what thoughts are regarding that. I didn't do that on the L-1; but it sounded plausible to me, and if the ejection forward can shear them; why not the aft. Anyway, curious if anyone has any insight there.
Kevin
In regards to shear pins for your aft/drogue section, that is a matter of preference. People do it both with and without successfully. On the 4" scratch built rocket I used for my L2 I did use shear pins both aft/drogue and nosecone/main. I lean that way because I feel like there is a little less need to mess around with the fit of the coupler, but friction fit will work. Whatever you decide, get it 'dialed-in' with your deployment charges during ground testing.
I was thinking about why the Apogee/Madcow Level2 kit builds stock with with shear pins for the nosecone/payload section, but apparently a friction fit for the aft fin can drogue section. What occurred to me was that if shear pins were used on the aft/drogue section, then when using a motor that has an ejection charge, would the motor's ejection charge be sufficient to provide the redundant droque separation at Apogee should the drogue BP charge fail? I guess it boils down to how much BP is required to shear those pins reliably and if the motors aft closure can hold that amount.
In Tim's videos, his rocket was saved by the motor ejection charge separating the friction fit aft section and drogue... would it have separated if it had shear pins instead?
Most standard motor ejection charges can hold enough powder to shear three nylon screws (2-56 or 4-40, ground test to make sure) in a smaller airframe, my 5.5" Cherokee D only uses 2 grams of BP in the drogue charge and it not only shears three 4-40s but also straightens the z-fold 30' harness to max during ground testing,and during flight (Lower Payload bay is 5.38" by 19").
This time I am weighing EVERY darned part of the system. I'll know what has been added via epoxy so I can keep real close track in my log book. Figure this will only help me later if I attempt an L-3. It's also St. Patties, so I have to enjoy something while working!!!
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I was thinking about why the Apogee/Madcow Level2 kit builds stock with with shear pins for the nosecone/payload section, but apparently a friction fit for the aft fin can drogue section. What occurred to me was that if shear pins were used on the aft/drogue section, then when using a motor that has an ejection charge, would the motor's ejection charge be sufficient to provide the redundant droque separation at Apogee should the drogue BP charge fail? I guess it boils down to how much BP is required to shear those pins reliably and if the motors aft closure can hold that amount.
In Tim's videos, his rocket was saved by the motor ejection charge separating the friction fit aft section and drogue... would it have separated if it had shear pins instead?
Kevin,
I've been following your thread with much enthusiasm. Thanks for all the details and congrats on your successful flight and L2.
I've been trying to get a handle on what the actual finished weight will be without the motor installed. What did your final weight turn out to be?
Thank you.
Kevin K.
Thanks Rich. This is definitely something I need to get a handle on. That's interesting data, seems the 5.5 inch diam helps with force.. but you also have sufficient momentum/velocity to thrust the section 30' is amazing for just 2g BP. I was just watching Kevin's drogue ejection ground test video. I think it showed that 1.4 g BP and three 2-56 pins failed, but 1.7g BP and just two 2-56 pins worked. I guess it all boils down to pressure over area and number of pins.
Kevin,
I was absolutely LESS than what the Rocksim file shows. I weighed every little piece during that build. In Rocksim I did a mass override of 146 oz and the cg at 40". Without the Mass override it stated 148.89oz and 38.6" for the CG. Neither of which was actual. So I left my overrides in place. Hope that helps.
I have to admit, I was surprised that the 1.4 failed. My Bp calculator stated it was the proper amount. I guess THIS is why we ground test! I will say I had three shear pins (I didn't listen to everyone). I removed one and upped the charge and as the video showed got a good separation (not only in ground test, but also in flight).
Thanks Kevin. I just ordered a kit last night, so I hope you don't mind that I'll probably hound you with some questions in the near future. =]
When you put in your mass override figures, mass override of 146 oz and the cg at 40", was that including your motor? If so, which motor?
Thanks Kevin. I just ordered a kit last night, so I hope you don't mind that I'll probably hound you with some questions in the near future. =]
When you put in your mass override figures, mass override of 146 oz and the cg at 40", was that including your motor? If so, which motor?
Just bear in mind that you need to ensure the 5:1 thrust weight ratio. The 250 was close, by the RSO and I agreed it could fly when I discussed my sims. It did well.
snip...
The Aero Pack 54mm L retainer slides right on either side of my 54mm tube. I've noticed that all these fiberglass tubes don't seem to have strict tolerance control. I think I'm seeing up to 0.010" variation in diameters and wall thickness.
...
The L type retainer body fits the thinner Loc style paper motor mount tube. The P retainer fits the slightly thicker phenolic tubing and those G-10 or Blue tube tubes which are sized the same.
Here's the sizing chart:
https://aeropack.net/webstore/partnumbers.asp
If your L type is too loose, how do your centering rings fit? I would expect the L type to be a very tight fit.
Edit: I'm still getting used to the thin wall g10. [emoji15]
Just be sure to sand the OD of the MMT before gluing the retainer body on with JBWeld and you should be fine.
[emoji1010] Steve Shannon, USA [emoji1010]
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