Hydra (Semroc) 54 MM Upscale Build

[markjos]

My wife would have already kicked me out of the house if I even thought about using the dining room table to build rockets!!!

My son and I have a running joke along these lines. When my wife goes away on the occasional weekend, parts of rocket projects tend to appear on the the kitchen table, then magically disappear just before she returns.

This looks great, Gary. Thanks for putting so much time into these posts. I can't wait to see the latest Hydra fly!

Mark
Central Illinois Aerospace
L2

 

[dixontj93060]

Mark
Central Illinois Aerospace
L2

HEY, THE LURKER POSTS!!!!

:jaw:

 

[gary7]

Spent about half the day Saturday repairing my electric car window. A cheap piece of plastic that works with the regulator (that motor that runs the windows up and down) needed replaced. About a 3-4 hour job. Ususally. Lost a piece inside the door and it took a couple of hours to get it out. So, more time was spent working on the car window than the rocket.

Got the remainder of the strakes and 1/3 of the ringtail fins epoxied on.

The rest of the time I spent working on a stand for this thing. 1st pic (used by permission) is one of the more common PVC rocket stands we see on this forum and in the field. That will not work with this rocket very well so I made my own, 2nd and 3rd pic's. I know, on this stand it looks like something out of "Star Wars" or "Battlestar Galactica".

Next pic is to show relative perspective of my current Hydra and the new upscale.

Obviously, I did not meet my self imposed deadline to get this project ready for paint by the 17th and I even took two days off work to do so.

Last pic, just more electronics bay work. Julie, my wife insisted.

 

[gary7]

All the fins and strakes are on, only thing left to do is reinforce the attachment points of the three main strakes with some epoxy at the ringtail then fillet and body finishing before paint.

As promised, here was my solution to getting the screw/hole into the pod for the rail button. Used one of my wife's craft punches to make a hole in the pod. Drilled the pilot in the oak button anchor block then lined them up. We have all seen right angle screw drivers like this one. It fit nicely in the pod tube so that I could secure the button. You can clearly see the button in place in the last pic. Yes, a 1010 rail will fit thru the ringtail.

 

[gary7]

... and thought I still did.

I really like the fillets I've seen made using microballoons. Have never tried it. Talked to people about it, looked it up on this forum. Never have seen it done. My two pics here prove I don't know how it's done either. Save your self some trouble and don't post a how to for me here and now, it's too late. Eventually, someday I'll learn how to do it the right way.

Until now, I have used Elmer's Carpenter's finish glue or epoxy clay for fillets. I think with my time limits, I would like to complete the three main fin external fillets like I did these two sides, then do the smaller ringtail fin fillets with the Elmer's. I would only hope the Elmer's sticks to the glassed ringtail. It probably will not since it is wood glue. We'll see but will probably spend the 9+ hours it will take to use the microballoons on the the ringtail fins too.

This has to be done and ready for primer in less than two days.

 

[dixontj93060]

This has to be done and ready for primer in less than two days.

Gary, what is the deadline for?

 

[gary7]

Gary, what is the deadline for?

Tim, if I don't get this flown at Thunderstruck, it will not fly before MWP in Oct. I can get it done if I sleep only 4 hrs/day for the next week. Or maybe if I don't paint it. I don't want to drive to IN with wet paint that has not had at least a couple of days to dry. I also know, I can't compromise build integrity either. My comment about the Elmer's was just that, a comment. I think I know better. And probably will be sleeping only 4 hrs/day. I appreciate your concern too! Thanks.

 

[gary7]

Good friends know how and when it is time to step in. In spite of my plea for no "how to" on fillet finishing, my CIA friend, Tim Dixon sent a personal note on fillet work and more. Thanks to Tim for his words of encouragement and instruction. His tip worked for me and I got done in half the time. The fin fillets are now complete. The only thing left to do is minor touch-up and fine sanding then I can start priming.

I might get this done in time for Thunderstruck afterall, without the odor of fresh paint in the Jeep on the way.

Thanks, Tim!

 

[dixontj93060]

Good friends know how and when it is time to step in. In spite of my plea for no "how to" on fillet finishing, my CIA friend, Tim Dixon sent a personal note on fillet work and more. Thanks to Tim for his words of encouragement and instruction. His tip worked for me and I got done in half the time. The fin fillets are now complete. The only thing left to do is minor touch-up and fine sanding then I can start priming.

I might get this done in time for Thunderstruck afterall, without the odor of fresh paint in the Jeep on the way.

Thanks, Tim!

Great to hear Gary!! :handshake:

 

[gary7]

The fillets have been still too tacky to paint today. Maybe I didn't mix it properly even tho I used measuring cups.

Anyway took time away from working on this version of my Hydra, to work on my other one. Actually, that work was prepping a J350. After one previous attempt, a repaired zipper, struggling with delay decisions and more, as of about 2pm today, I am now an NAR L2! It was a beautiful straight up flight with perfect apogee deployment.



Since this rocket under construction requires a 54 mm ride, thought it just might help to have that L2 before I went to Thunderstruck next weekend.

Spent about five hours with the local group flying on a perfect afternoon for doing so.


Need to change my forum signature to L2! Now, back to work, right after I go celebrate.

 

[jungmann1]

That's awesome, Gary! Congratulations! John.:clap::clap::clap:

 

[gary7]

My good friend grimracer turned me on to these push pin switches. Set side by side as seen, one pin inserted thru one of the avionics bay port holes, will activate both switches which in turn activate both altimeters when pulled out at the pad.

I know, many of you do not subscribe to having the same kind of altimeters in the same bay. That discussion can be seen elsewhere on this forum so no need to open that here, thank you.

 

[gdjsky01]

Congrats on yer L2! :clap:
And thanks for a fantastic build thread.

 

[fyrwrxz]

My good friend grimracer turned me on to these push pin switches. Set side by side as seen, one pin inserted thru one of the avionics bay port holes, will activate both switches which in turn activate both altimeters when pulled out at the pad.

I know, many of you do not subscribe to having the same kind of altimeters in the same bay. That discussion can be seen elsewhere on this forum so no need to open that here, thank you.

Craftmanship at it's finest, sir! Really interested in the pull pin switches so when you get a chance (after you launch!) could you give a little more info? I've used rollers for safety in a two stage, but those break the circuit. What are these that complete the circuit when the pin is removed? Much more elegant than the typical screw or positive detents I'm currently using. Thanks for the great build thread, I know they are a real pain to document. I don't have the patience nor camera savvy to post! Best of flights to ya!

 

[gary7]

Thank you for remarks, fyrwrxz. These switches can be found here at PerfectFlite. I just removed the activation lever and replace it's action with the pin.

 

[gary7]

You never know just how bad things are with your finish until the primer goes on. Then everything shows! A couple of the ringtail fin fillets look pretty awful, the rest is ok. But finish work isn't now nor has it ever been a strong point in my rocket building as I mentioned before.

But, it'll still fly and I want to fly it this week. So I'll finish it tomorrow and Wednesday then if I ever have the time or the inclination to repair the fillets, I'll do so. For now, here is the primed Hydra XL 77. Hydra, because it is; XL, because it is and 77, because it is about that tall and it corresponds to a very special date in my life.

In the background you can see some of my fleet, some of which will accompany this beast at Thunderstruck!

 

[qquake2k]

Anyway took time away from working on this version of my Hydra, to work on my other one. Actually, that work was prepping a J350. After one previous attempt, a repaired zipper, struggling with delay decisions and more, as of about 2pm today, I am now an NAR L2! It was a beautiful straight up flight with perfect apogee deployment.

Need to change my forum signature to L2! Now, back to work, right after I go celebrate.

Congrats on the L2! I'll spare you the usual wallet jokes. LOL

 

[qquake2k]

My good friend grimracer turned me on to these push pin switches. Set side by side as seen, one pin inserted thru one of the avionics bay port holes, will activate both switches which in turn activate both altimeters when pulled out at the pad.

I know, many of you do not subscribe to having the same kind of altimeters in the same bay. That discussion can be seen elsewhere on this forum so no need to open that here, thank you.

I really like that switch arrangement. A lot. You can get a "Remove Before Flight" flag for the pin. That would be cool!

 

[qquake2k]

You never know just how bad things are with your finish until the primer goes on. Then everything shows! A couple of the ringtail fin fillets look pretty awful, the rest is ok. But finish work isn't now nor has it ever been a strong point in my rocket building as I mentioned before.

But, it'll still fly and I want to fly it this week. So I'll finish it tomorrow and Wednesday then if I ever have the time or the inclination to repair the fillets, I'll do so. For now, here is the primed Hydra XL 77. Hydra, because it is; XL, because it is and 77, because it is about that tall and it corresponds to a very special date in my life.

In the background you can see some of my fleet, some of which will accompany this beast at Thunderstruck!

You won't see the flaws when she's in the air. That is one beautiful beast!

 

[gary7]

Thanks, Quake.

 

[gary7]

Got the paint done but with a little added something extra. I had lined the wrapper on my other Hydra as well but with smaller lines.Those lines aren't in this picture because I had to remove them when it zippered last fall after taking off an unstable pad then flying in a near horizontal path. This one isn't as eye appealing as I would have liked. Should have used more narrow lines.

Anyway, the thing is all but done. Here my two Hydras are side by side one more time for comparison.

I am leaving for Thunderstruck soon. Forecast for the next couple of days is "iffy" for me as far as flying this thing. Depends alot on the wind. I just don't like flying in the wind.

Weather permitting, I'll fly both this weekend. Planned is a first flight on a K550, if I can find one at the launch for the new one. Hope to have flight pics when it is all said and done. Wish me luck please!

 

[markjos]

I don't know whether you'll see this from Lafayette, but Gary, not only did you make your deadline, but the rocket really looks great. We know how hard you've worked on this project, and now that I've seen the rocket in person, there's no doubt that the craftsmanship is really outstanding. Congratulations.

I won't make it to Thunderstruck until late on Friday, but I'm looking forward to seeing you and your fleet there - hope I catch some of your flights.

Mark

 

[gary7]

Well, sort of. Wonder what this rocket would do with a 75 mm MMT??? Please, no one tell my wife I asked that question!

Flew this thing at Thunderstruck today. More stressful and exciting at the same time than I can ever remember in my entire life. I think it was a crowd pleaser as well. Had planned to light a K550 under it but the Wildman only had a K540. It worked.

Have posted some teaser pics. Thanks to the Smith family of Ottowa, IL. Will have a video as well later.

Thanks to everyone involved in getting this built and ready for my flight. Special thanks to my wife, Julie for putting up with me these past few weeks and my two youngest daughters for me not listening as much and not seeing them as much either.

 

[gary7]

Video of the first flight of the Hydra XL: https://www.youtube.com/watch?v=IrBNasFR4Nc&list=FLMFZSB1jcTMCaLUj_BR6xwQ&index=1&feature=plpp_video

This was my first L2 flight! I just certified on my smaller version a week ago.

Hydra came within a couple hundred yards or so of the pads. No damage and will fly next time at MWP in October!

Two on-board Adept 22 altimeters reported an altitude of just over 3100 feet and were within 20 feet of each other. Rocksim predicted an altitude of just under 1900 feet on that K540. Any ideas or suggestions why such a discrepancy? It was too overcast and the rocket got lost temporarily in the clouds so unable to get an eye ball estimate of the altitude. I thought that maybe the wraps just above the ports may have caused those readings but surely the deployments were fine. Again, we couldn't see it happen due to the overcast sky.

Thanks for viewing this thread. It was work but fun posting the results. I appreciate everyone's comments. Thanks again, Gary

 

[qquake2k]

Awesome flight!

 

[DAllen]

Video of the first flight of the Hydra XL: https://www.youtube.com/watch?v=IrBNasFR4Nc&list=FLMFZSB1jcTMCaLUj_BR6xwQ&index=1&feature=plpp_video

This was my first L2 flight! I just certified on my smaller version a week ago.

Hydra came within a couple hundred yards or so of the pads. No damage and will fly next time at MWP in October!

Two on-board Adept 22 altimeters reported an altitude of just over 3100 feet and were within 20 feet of each other. Rocksim predicted an altitude of just under 1900 feet on that K540. Any ideas or suggestions why such a discrepancy? It was too overcast and the rocket got lost temporarily in the clouds so unable to get an eye ball estimate of the altitude. I thought that maybe the wraps just above the ports may have caused those readings but surely the deployments were fine. Again, we couldn't see it happen due to the overcast sky.

Thanks for viewing this thread. It was work but fun posting the results. I appreciate everyone's comments. Thanks again, Gary

Check your over-all weight that the simulation shows and make sure it matches the real world. If that proves to be correct then it will probably mean RS is not correctly predicting Cd which doesn't surprise me too much with that ring-tail. To fix it I suspect you will have to lower the Cd until the simulations match real world...unless someone has a better idea that I am missing.

Nice build by the way.

-Dave

 

[ECayemberg]

Great build and sweet flight Gary!

Regarding altitude, I agree with Dave, adjust the CD (masses if they need to be) until it matches the performance of the flight, then use that adjusted CD for future simulations.

I believe the Adept 22's readings, based on several flights before the cloud cover departed, I think the cloud base was about 1600' or so. Had the Hydra hit *only* 1900', it would've been fairly slow by the time it disappeared into the clouds; it was still honkin' pretty good when it disappeared.

Re: like altimeters and especially Adept22's, I flew a pair of Adept22's in my Magnum about an hour after the Hydra flight. Love the Adept 22's!

Again, great job on the accelerated build schedule!

-Eric-

 

[gary7]

Case closed. Well, sort of. Wonder what this rocket would do with a 75 mm MMT??? Please, no one tell my wife I asked that question!

That's right, the 54 MM version just wasn't quite big enough. Rough fitting some parts to show some perspective. I already have the L2200. It is going to need it. The ringtail alone weighs about 2 pounds.

Now tell me I am crazy if you want to but I know there are some of you out there just dying to do this sort of thing yourself. So "grow some" and get busy!

See you at Thunderstruck.

 

[qquake2k]

View attachment 119276

That's right, the 54 MM version just wasn't quite big enough. Rough fitting some parts to show some perspective. I already have the L2200. It is going to need it. The ringtail alone weighs about 2 pounds.

Now tell me I am crazy if you want to but I know there are some of you out there just dying to do this sort of thing yourself. So "grow some" and get busy!

See you at Thunderstruck.

You might be crazy, but in a good way!

 

[gary7]

Making progress.

The half cones for the pods need to be epoxied on.
Need fillets on all the fins.
Afterwards some filler, lots of it, then sanding, lots of that too of course.

The weight keeps going up. Finished weight with the L2200 should be close to 45 pounds. Ouch!