Streamer Recovery

Hey All, apologies in advance for the uninformed question that I'm sure has been asked countless times:

Is there a rule of thumb as to the safe use of a streamer recovery system? I ask, being at least aware of the variables involved (weight, profile/drag index and associated terminal velocity, number of streamers/size of streamers and associated drag coefficient, etc.). I'm working on learning the mathematics and rocket science, but for the time being, I was wondering if anyone had a good rule of thumb on maximum safe weight for a streamer recovery.

My reason for asking:

I would more than likely like to modify my Estes Short Round to a streamer recovery system, and I am completing an Estes Alpha III tonight and will be starting an Estes Alpha tomorrow and am interested in streamer recovery for the sake of weight savings and maximum Delta V/altitude and a reduced recovery zone. If the wind is light or calm, I don't see a reason to ever NOT use a parachute as it results in the highest drag coefficient, lowest terminal velocity, lowest decent rate and softest touchdown, though I'm interested in options with different wind conditions, aloft and at the surface. Thanks in advance!

if there is enough room for it, I don't know if there is an upper limit. I've heard of streamer birds thermalling out of sight.
Rex

I suggest trying your alpha on an A8-3 1st or a B6-4, you would be surprised how easy it is to lose sight of an alpha at 800'
Rex

Rex R said:

I suggest trying your alpha on an A8-3 1st or a B6-4, you would be surprised how easy it is to lose sight of an alpha at 800'
Rex

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Yup, that's the plan. I'm going to first flight it tomorrow morning on an Estes A8-3. If all goes well, I will run an Estes B6-4. As long as the wind is calm, I MAY get saucy if it's going good and run a C6-5 on the third flight, but we'll see if I get cold feet when the time comes The plan for now is to utilize the standard 12" parachute and make a go/no-go call based on winds in the morning.

That being said, I'm intrigued by streamer recovery and want to look more into it for lightweight rockets.

A streamer produces less drag than a parachute, therefore the rocket will drop more quickly and land harder, so the first question is what sort of surface will the rocket hit? If it's relatively soft, e.g. grass, then a streamer is fine; if it's hard, e.g. concrete or dry-baked earth, dropping a rocket on a streamer is likely to result in fins needing to be glued back on, at the very least.

One compromise is to have a parachute with reduced surface area. The easiest way is to cut a spill hole in the parachute. Or you can get a smaller parachute - perhaps cut that 12" parachute down to 9" before attaching the shroud lines. Top Flight make some nice small parachutes:
https://topflightrecoveryllc.homestead.com/page1.html
https://topflightrecoveryllc.homestead.com/thinmil.html

I've used both their 9" standard and 10" X-form in small rockets successfully. And nylon lasts a lot better than thin plastic. Rather than each rocket having its own parachute, I have a few good nylon parachutes, one of which is loaded into the rocket before flight and removed shortly after - on some occasions I launch a rocket, remove its parachute, install the parachute into the next rocket and then launch that. The X-form in particular is a good compromise between the quick descent of a streamer and the safe descent of a full parachute.

I fly quite a bit of competition at the NAR chapter I belong to, and that almost always includes streamer and/or parachute duration. Here are a few observations about flying tha Alpha on streamer vs chutes:

1) if your Alpha will be landing in tall or medium grass (we fly in a cow pasture), the Alpha doesn't need either. We fly Alpha's for Spot Landing with just nose blow recovery all the time with no damage.

2) if you are landing on short grass, a streamer will often be sufficient, and will bring the model down faster (and, hence, less subject to wind drift). The puny streamers that Estes includes in their kits won't do much. A cheap alternative is flame resistant crepe paper - get the kind in the 2 or 2-1/2" wide rolls. You can get a lot of colors, so get either bright orange or black for visibility. Using crepe paper, cut a piece about 6 feet long, fold in half and attach at the center to your shock cord near the nose cone.

3) Chutes can drift a lot. If it is breezy (and consider there may be little wind at the ground, but a couple hundred feet up, the wind could be a different direction and considerably stronger) you might want to either cut a spill hole or reef your chute (wrap a small piece of tape around the shroud lines about half way up - this will keep the chute from opening fully and can be removed if need be). If you are landing on hard packed dirt or pavement, however, you want a fully open chute. Be aware that even with a decent sized chute, landing on pavement may still result in broken fins - it is a hazard of the sport.

I have a 12"-ish streamer on my Alpha. Works fine although occasionally the rocket will land in hard dirt and break a fin. Keep in mind though that the rocket is 20 years old and I didn't glue the fins on as well back then as I do now. I fly it in my back yard with ! motors, plenty of performance for backyard flying but it doesn't get too far away on the descent.

I would highly recommend getting the book, Handbook of Model Rocketry, by G. Harry Stine and Bill Stine. There is a lot of information in there about the principals of rocketry, that are a applicable to model rockets as well as high power rockets.

https://www.amazon.com/dp/0471472425/?tag=skimlinks_replacement-20 to order or check out your local library.



Greg

GregGleason said:

I would highly recommend getting the book, Handbook of Model Rocketry, by G. Harry Stine and Bill Stine. There is a lot of information in there about the principals of rocketry, that are a applicable to model rockets as well as high power rockets.

https://www.amazon.com/dp/0471472425/?tag=skimlinks_replacement-20 to order or check out your local library.

View attachment 269883

Greg

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It will arrive today actually! I ordered it a couple days ago on Amazon along with a 12 pack of Alphas and an Estes Tube Marking Guide. Thanks for all the wisdom, guidance and advice all! It is logical, makes sense and is greatly appreciated.

If you build scratch, or if you don't mind modifying kits, position your fins so that the tail end of the rocket is the furthest back part, (therefore the engine will stick out a bit more if you used engine hook or tape retention).
Specifically, if you can stand the rocket on its fins, by this technique the fins are too far back.
Reversing the fin sweep will accomplish this in a lot of cases. Point is, when the rocket hits the ground, the butt edge of the engine is what takes the impact. This works with streamer or chute recovery.
Be aware this will alter the center of pressure (CP) a bit, might change your stability I/2 caliber or so.
This greatly reduces fin breakage due to landing stress.
Plus, IMO, forward swept fins just look cooler!