Pop at the Top!

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Kruegon

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As my flight apogees continue to rise, I'm exploring dual deployment. Until then, I'm still having to pop at the top. So I wonder:

What's the highest altitude you'd be willing to pop at the top and why?
 
I routinely pop at the top at 2000' or less. My rockets are sized large enough to just be visible to my geezerly eyes. YMMV.
 
Well, you are kinda limited by the delay of the engine. To maximize your altitude with motor deploy, you have to A) Play with it to keep it subsonic (your Cd goes way up in the transonic region) B) punch thru as quickly as possible C) balance the available thrust with optimum mass for coasting. This is fun and interesting all by itself and can keep you busy for years! Keep in mind delays are the 'black art' of motor making and are not all that precise yet. Seems al reloadable motors are fractionally different each time and this affects your ultimate altitude. Straight smoke and good chutes!
 
I've flown to 3250' with motor deploy and plan to go higher. Dual deploy helps above around 2K but you can fly to 4K+ with single deploy if your field is big enough.

It also really depends on the descent rate of your rocket under chute. A FG rocket falling at 30 fps is easier to recover than a less durable rocket that has to descend slower to prevent damage.
 
Launch conditions play a major role in determining maximum motor (single) deploy altitude.

It it windy or calm?
What are the wind conditions at altitude?
Are you launching on a dry lake bed, a farmers field, or in a 1/4 mile square clearing in forest?
What are the air quality and sky conditions like?
How many dedicated helpers do you have watching the flight?


You can be more confident with "Pop at the Top" if you have an RF tracker to help you recover the rocket.

I flew and recovered successfully to about 3500' single deploy and visual recovery at MWP11 (Farmland after the crops have been harvested) Even with a crystal clear blue sky and low surface wind I was pretty lucky to have a good spotting crew. I completely lost sight of the rocket while trying to film it.
 
My 7.5" rocket hit 4200' at our last launch with an unintentional main deployment at apogee. I wound up walking about 1/4" mile to pick it up. Last year at the same launch I launched a Leviathan to 1800' and wound up walking, er hiking, about 3/4 mile.

It really depends on where you are launching and what the wind is like.
 
I think SCrocketfan hit the nails on the heads. It depends on the rocket and the field. I will also add current weather conditions to that. It comes down to learning to fly the field and conditions. I don't think there is any set altitude where you should not pop at the top. As you move up in motor sizes and altitudes, you learn more about flying the field and the current weather conditions. At the same field, I'll use motor eject on +3000 ft flights on some days, but won't try anything above 1000 ft on others depending on wind and weather conditions.

The short answer to your question is really "It depends!". I know that isn't a very good answer, but it depends.....
 
Since I am a devotee of the top popping, I rely on a tracker to get my junk back. Depending on the field, I can and will go to the 3500'-4000' range. I would actually like to go a little more. I have a secret desire to hit a mile with apogee deploy just to say it happened. The conditions and launch site have to be really right though.
 
Never....when flying high power.
I don't like to walk, so everything is DD.

PS: I don't count E's..F's & G's in stuff going 5-600ft. I don't fly these on windy days.

I do have 2 rockets specifically designed for flying "pop at the top" but those have special streamers, are made from FG[so no damage from hard hits] and drop straight, like rocks from over 6000ft. on H's & I's & utilize trackers.


Your question is very "non specific" as to what you are flying.

I did fly one N designed to pop at 40,000. But did not care about any damage, just wanted the altitude.
 
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Don't forget, popping at the top doesn't necessarily mean motor deploy. I've done electronic for apogee only, just to avoid the inconsistency with motor delays. I hate zippers and will do anything to avoid 'em.
I'll agree with Jim. H and above I don't bother with motor deploy. I've done dual deploy under 2k, just to be able to watch the whole sequence unfold (literally) before stepping it up.
-Ken
 
Well the topic isn't about what rocket. I'm just curious as what altitude people are willing to brave popping off and why they will or will not at higher alts.

For the moment, I've been contemplating the flight of an Estes Majestic on an HPR motor. The H128 sims to 3600' but at a speed just over mach. I'm doubting the rocket would survive. Even if it did, drift would probably kill it's recovery. Crashed rocket I can live with. Lost motor I can't.
 
That's pretty much what I was thinking. I've got a bit to learn about HPR SU motors. I did all the learning I needed on HPR RMS but never researched LMS or SU for HPR. I also have never seen the DMS delay tool used. I still have a lot to learn about HPR.
 
What's a no wind day? That sounds like someone's fairytale dream. I have never had a launch with no wind. But this fall I just might brave a 3500' pop at the top.
 
What's a no wind day? That sounds like someone's fairytale dream. I have never had a launch with no wind. But this fall I just might brave a 3500' pop at the top.

We get them a lot in Florida in the summer.
 
What's a no wind day? That sounds like someone's fairytale dream. I have never had a launch with no wind. But this fall I just might brave a 3500' pop at the top.

We have had a few at the ROC launches a few months ago, by no wind I mean the flags were hanging on their poles and the smoke trails just hung in the air. And yes it was a dream and rare. We launched as fast as we could reload, since the kids are my recovery minions they were ex cited to only have short walks.
 
It really depends on the field, conditions, motor, and rocket. If I were expecting to hit 2,000 feet at the Sod Farm, I'd try for DD if at all possible. If not possible, I'd see how other things were flying and make a judgment call on whether I wanted to run it or not.

You might want to revisit your flight strategies AFTER you get comfortable with dual deployment. What seems like a routine, delay-cutting, motor-ejection flight today may well seem overly risky once you're comfortable with DD.


Later!

--Coop
 
What's a no wind day? That sounds like someone's fairytale dream. I have never had a launch with no wind. But this fall I just might brave a 3500' pop at the top.

We had one April '14 at BattlePark. It was "almost" a no wind day. There were 5 mph winds but only below 300 ft.

I had a mishap and popped the main at 6402 ft. The altimeter showed 340 seconds from main deploy to landing (18.8 ft/sec decent rate). The low level winds caught it at about 300 ft and it landed about 500 ft from the pads. It was kind of a weird day. The LPR guys were taking longer walks then the HPR guys flying much higher.
 
Well the topic isn't about what rocket. I'm just curious as what altitude people are willing to brave popping off and why they will or will not at higher alts.

The reason I asked about "what rocket" :

It makes quite a difference in what the rocket is made of & what size when pushing the limit of recovery.
Take a small "mini" style rocket, say 38mm airframe & 29mm motor, when made of paper, is so light it will drift significantly, if just using a streamer.

Take the same rocket made of thin wall fiberglass & it's so much stronger and heavier, you can fly it too the limit with a streamer, still feel comfortable knowing it can survive a hard hit. Being somewhat heavier, drop many times faster & land closer to the pad than the paper version under a variety of wind situations. In this scenario, where the paper rocket drifts so much, I would not fly it over 800-1000 ft...but the glass version would fly easily to 4-5000 ft. and pop at top.

Same thing goes for larger project where you can get by with a tiny chute in the glass version, vs needing a larger chute in paper, for survivability reasons. You can hit the ground safely at 35-45 ft vs 15-20ft with out damage.......once again cutting the recovery walk in half.....that was my reason for asking.
I have several rockets made of glass where recovery was less than optimal, [chute never opened] that hit ground & bounce, with no damage what so ever.:smile:

PS: In O'burg where I fly, in summer months there are many launches with no or very little breeze. So much so, being 90-100 out, you wished there was more wind.lol

On another note: when flying minimum diameter or even light rockets on big motors, many times the delays are not long enough, requiring electronic deploy, even if just doing single deployment at the top. The supplied delay or even drop in long delays would fire[if doing motor eject] while your still going at a high rate of speed in the coast faze,then bad things happen.

You must also remove/not use BP in the motor, to prevent this.
 
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I have one rocket that I like to fly and I routinely dump the laundry at 10k. The furthest walk has been just over a mile. This isn't with a fast descent either - last time it came down at just over 12 feet per second.

Edward
 
What a bunch of wimps, how about 12k? Of course, this in on the salt flats with a tracker:

[video]https://youtu.be/xHuJgLecblg[/video]

Landed two miles away, drove straight to it.
 
I do 4-5k but people think I am crazy.

I'd be fine with altitudes like that with tracking… Probably only 4K with no tracking, but I wouldn't even fly dual deploy to much over 4K without tracking.

At Black Rock, with tracking, it seems like 10-15K is reasonable, but dual deploy still can't hurt.
 
I have one rocket that I like to fly and I routinely dump the laundry at 10k. The furthest walk has been just over a mile. This isn't with a fast descent either - last time it came down at just over 12 feet per second.

Edward

You must have no winds at all in your area.

Here at BattlePark the upper level winds are usually +35 mph at 9K and 10mph at the surface. Using and average of 25 mph and 15ft/sec drop from 10K for a 666 second flight, that would give you a drift of just over 4.5 miles.

Or are you talking about going 10K above MSL and your launch site at over 9.5K ft. above MSL already?
 
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