Leviathan on an E30-4 Motor?

Has anyone ever flown an Estes Leviathan on an Aerotech E30-4? The club my daughter and I fly with has an "E" motor limit, and my daughter and I want to fly our Leviathans. I simmed it in OR, and it looks like it will work to about 390 ft, but am I pushing my luck, or will it be a safe if unspectacular flight?

A lot may depend on how you build it, but I show ~650 grams with an AT E30-4, 30mph off the rail to about 300ft.

I probably wouldn't do it myself, any coning or weathercocking could force that 24" nylon not to open fast enough.

Check the speed of your rocket as it leaves the launch rail. I have lowballed a few birds on their maiden flights with sims giving me a speed of 41 ft/sec off the rail. Great low flight.
Just looking at the thrust curve of that motor, it peaks at 49 N pretty darn quick. That is roughly 11lbs of thrust. 5 to 1 rule and it should lift a bird weighing just over two lbs. If your Leviathan doesn't weigh more than that, it should be fine.

Mike

I'd try it, in calm wind.

I've done it on an F44-4 economax, which isn't much more than an E30 total impulse-wise. It was plenty fast off the 1/4" estes porta rod. My Leviathan is 18.4 Oz w/o motor for reference. 4 seconds put it deploying just past apogee.

Yeah I ran some sims in OR. Saying velocity off rod is at 49.5 ft/s. Sims for my Wildman Sport shows velocity off rod of 40 to 41 ft/s on the motors I fly it on. Straight flights, no problems. The last flight was on a G53 - sims at 40.6 ft/s off the rail. And it flew perfect to just over 1000ft (simmed, no altimeter yet). And it was windy...very windy. But it had a stability of only 1.04, and it didn't weathercock at all. But the wind sure carried it on the chute quite a ways.

If possible, take the top section of BT out and fly it as a Big Daddy! Big Daddies love E20s and E30s. I left my partizon to where I could fly it with or without the top section, and will do the same with my Leviathan, if I ever build it.

Mike

Without knowing your weight and paint finish I can not provide you with any data.
What are the details of your build?

Should work... but with very little room for error. It's ultimately up to the guy with his finger on the button.

TopRamen said:

Without knowing your weight and paint finish I can not provide you with any data.
What are the details of your build?

Click to expand...

Well, since you asked:



I built it with woodglue throughout except for some JB Weld on the motor mount and some epoxy on a u-bolt. I added a u-bolt to the upper centering ring, and have a loop of Kevlar through it. Shock cord is knotted to this, and the other end has a quick link that has the parachute and swivel, and short piece of kevlar tied to nosecone. Small amount of CWF on fins and spirals. Two light coats of primer, sanding in-between. Couple of light coats of white on body, and then slightly thicker final coat, fin can masked and painted red. Couple light coats, then final coat slightly thicker. Nosecone painted green same method. Not the best painter, but looks ok. It has lugs and railbuttons. Weight on my little digital scale come out as 510 grams (17.9 oz) empty.

My daughter's is still in primer, but built the same way. She wants to paint "rainbow swirl," so not sure how much that will weigh.

Flyfalcons said:

I'd try it, in calm wind.

Click to expand...

Too windy today--must have been 15 mph, so just left it at home. Maybe next month.

I've flown slightly bigger on the E20-4, 400' with perfect apogee deploy. Also E12-4 but that belongs in the craziest recovery thread. Doesn't Estes recommend their 29 mm E16 now? BTW I hear the RMS E18's are really loud .

They just recommend composites.

Forgot Estes was out of them, but look at https://www.estesrockets.com/rockets/pro-series/rockets/builder-kits/009712-pro-series-iitm-sciontm
I guess the E16 doesn't get enough altitude for even a -4 though.

The older pages for Ventris, etc. do still just say composites though.

Don't forget to look through launch reports on rocketreviews.com

No substitute for real data.

I tried it last Saturday. Beautiful day with calm wind. It flew great.

Low wind make all the difference. No wind = no weathercocking = no problem.

And the video:

[YOUTUBE]cqSTP_E3F-M[/YOUTUBE]

Love that Also Spach Zarathrusta!