Extreme Airmail! Mailing Tube Rocket

[Long_Gone]

Those are awfully small and ineffective fins. That thing doesn't do somersaults off the launch rod?

Like I said its a fin can from thingiverse and the string test is fine. I have not been able to fly it yet but it may be exciting.

LG~

 

[Weldo]

Hey guys! It's been a while!

Since the quarantine ended and stores opened up again, I finally got out to buy motors for this rocket.

As stated before I'm going to try the Estes D12-3 first and see what happens. My sister and I had a chance to launch this thing last Sunday!

I present, the footage:



Forgive the shakiness, my camera's image stabilization wasn't turned on...

 

[neil_w]

Now that is what you call low and slow.

How much does the rocket weigh? Clearly too much for a D12...

 

[Weldo]

Haha, yes. I thought the flight was a lot of fun to watch!

The rocket is around 18.2 ounces or so ready to fly. Estes max is 14 ounces for a D12-3.

I feel like if the delay was shorter that it would work. The motors were marked D12-3 but the actual delay was closer to 4-5 seconds. I was hoping the chute would deploy just a few feet above the ground.

So now I'm thinking I need pretty much zero delay since this rocket doesn't really have a "coast" phase. Could I add a small ejection charge to a D12-0 booster motor? I know some guys make their own ejections with a tiny charge of black powder. They are usually ignited by electronic means. What if I sealed a tiny packet of black powder to the top of a booster motor?

 

[neil_w]

What you need, if I may state the obvious, is a more powerful motor. Even an E won't go too high with an 18 oz rocket (and I'm talking a composite E, not an Estes E12 or anything). That flight went straight up, but no guarantee that's going to happen every time when going that slow. One gust of wind and all bets are off.

 

[Weldo]

Oh yea, that's for sure. I want to buy some Aerotech E30 motors for a proper flight, I just haven't gotten around to spending the money on them yet. I will try that in the future definitely. Maybe even F24. The trouble with the more powerful motors is that the altitude may become so high that recovery of the model may be uncertain.

 

[neil_w]

Oh yea, that's for sure. I want to buy some Aerotech E30 motors for a proper flight, I just haven't gotten around to spending the money on them yet. I will try that in the future definitely. Maybe even F24. The trouble with the more powerful motors is that the altitude may become so high that recovery of the model may be uncertain.

Throw it into OR, if you haven't already. I'll bet an E won't go very high. Of course recovery is always a concern.

[edit: sorry I just saw you started off with an OR model in post #1. What does the sim say for E20 and E30 motors?]

 

[Nytrunner]

The trouble with the more powerful motors is that the altitude may become so high that recovery of the model may be uncertain.

This is part of becoming a skilled rocketeer. Flying the field (safely). You may not "need" a waiver for some F flights, but a club may be the only ones with a field large enough to fly it at practically

 

[mbeels]

Or even a composite D, something like a D21 works very well for porky rockets.

 

[jqavins]

Based on the altitude you got from a D12, my guess is that with an E you'll still able to read the lettering at apogee.

 

[Ronz Rocketz]

I was gonna ask how much mail can it deliver and what's the postage...

 

[Weldo]

OR says for Aerotech E20-4:
Launch rod speed (71" rod) - 46.7 ft/s
Apogee - 453 ft
Optimum delay - 3.99 s
Velocity @ deployment - 12.5 ft/s
Time to apogee - 5.72 s

Aerotech E30-4:
Launch rod speed (71" rod) - 56.1 ft/s
Apogee - 578 ft
Optimum delay - 4.82 s
Velocity @ deployment - 35.8 ft/s
Time to apogee - 5.78 s

Based on OR it looks like the E20-4 is almost the perfect engine for this rocket.

I tried the sim for Estes E12 but it's not much different from the D12. Launch rod speed is a few tenths slower and apogee is maybe 40 feet higher.

 

[Nytrunner]

tried the sim for Estes E12 but it's not much different from the D12. Launch rod speed is a few tenths slower and apogee is maybe 40 feet higher.

Sounds right. As mentioned above, the D and E 12 both have the same initial lifting thrust. Heck the E12 has more mass too, so it may even get less off-rail velocity

 

[Weldo]

Just bought a pack of Aerotech E20-4! Hobbylinc has a discount going right now.