Streamer(s) Instead of a Drogue Chute on a HPR

Looking for a calculator which would give me rate of descent for a rocket of a given weight and streamer of a given length/ width. Saw a calculator based on Van Milligan's book, but it didn't give the descent speed- it only calculated the streamer size for what I assume to be a safe landing speed for using a streamer instead of a main chute.

Playing around with the idea of using streamer(s) instead of a drogue chute. Rocket weighs 6 1/2 pounds with 38mm motor casing. Will use a main chute deployed by an altimeter. Tried to use Rocksim to calculate streamer descent, but was unsuccessful. I have a two Top Flight 70" x 5" Ultra streamers and one 80" x 6" Ultra streamer. Any suggestions?

Hi
Very glad to see your useing the Ultra streamers
Check out rocketreviews.com/streamer-calculator.html
Gary
TFRLLC

Hi Gary- I was referring to that specific tool which you mentioned- I should have added the link with my post. That calculator gives me a recommendation of 641 inches length for a 6" wide streamer, which I'm sure must be for a descent speed of about 20 fps. But I'm looking for a way to calculate the descent speed using the different sized streamers which I mentioned. Want to use a streamer instead of a drogue chute, so I'd be happy with a descent speed of maybe 80-90 fps.

Btw- beautiful craftsmanship on the streamers!

the rocket-reviews is a calculator based on VM's book. Sunward has a write up on calaculations here: https://www.sunward1.com/images-tarc/Streamer Calculations (Cooke) (Jun 09).pdf You'd have to build your own calculator (could do it in excel pretty easily).

I'd be curious how excessively long streamers increase or decrease the total drag - like 100:1 to 150:1. I only ask because I have one of these (https://www.emmakites.com/50ft-rainbow-nylon-kite-tail_p194.html) I've been dying to put into a rocket. I got it with a spool of lightweight kevlar line I use in LPR rockets, and it just seemed like something I might use. I was going to put it in my WM Jr, but it won't fit into a 2" body tube.

JordanT said:

I only ask because I have one of these (https://www.emmakites.com/50ft-rainbow-nylon-kite-tail_p194.html) I've been dying to put into a rocket. I got it with a spool of lightweight kevlar line I use in LPR rockets, and it just seemed like something I might use. I was going to put it in my WM Jr, but it won't fit into a 2" body tube.

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Did you miss my flight in December when I used a 20+ foot tubular rainbow colored kit streamer in a 5.5" 6' rocket? I didn't fly it dual deploy I flew single deploy and it was flown with a 60" hemi parachute - they didn't tangle but it wasn't as clean as I would have preferred.

JordanT said:

the rocket-reviews is a calculator based on VM's book. Sunward has a write up on calaculations here: https://www.sunward1.com/images-tarc/Streamer Calculations (Cooke) (Jun 09).pdf You'd have to build your own calculator (could do it in excel pretty easily).

I'd be curious how excessively long streamers increase or decrease the total drag - like 100:1 to 150:1. I only ask because I have one of these (https://www.emmakites.com/50ft-rainbow-nylon-kite-tail_p194.html) I've been dying to put into a rocket. I got it with a spool of lightweight kevlar line I use in LPR rockets, and it just seemed like something I might use. I was going to put it in my WM Jr, but it won't fit into a 2" body tube.

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I used a 30 ft x 6" streamer on a 2.5lb rocket instead of a chute and it was too long and it drifted quite a ways. I think you should cut that 50 footer in half. Looong streamers can interfere with your main event.

UncleVanya said:

Did you miss my flight in December when I used a 20+ foot tubular rainbow colored kit streamer in a 5.5" 6' rocket? I didn't fly it dual deploy I flew single deploy and it was flown with a 60" hemi parachute - they didn't tangle but it wasn't as clean as I would have preferred.

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I did miss that one. I have a 25' tubular as well, but it packs to almost exactly the same size as the 50' streamer. I was actually thinking of using the streamer to bring back the 5" Jart on single deploy flights, but wondered if I could expect lower or higher performance. The 10:1 calculator predicts a safe recovery of close to 5 lbs on it.

It's somewhat of a religous argument, but there's no overpowering reason to use a drogue or streamer at all. Just let the parts tumble while tethered together. IMHO the main reason to use a drogue is a) to pull the main parachute out of the body tube. b) make sure the right end is pointed up when the main parachute ejects.

I can't speak to multi-hundred pound projects though.


-->MCS

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If you run a sim with Open Rocket inputting the streamer to deploy at apogee, and the main at some fixed altitude, the "deployment velocity" is the speed at which the rocket will be traveling when the main deploys, i.e. under drogue (your streamer). You can enter the dimensions of your streamer and you will have a good idea if it is gonna work.
I don't have Rocksim, so I can't say if it will give you a similar value.

I know, clear as mud... Hope it helps.
Terry

Thanks- I didn't know about Open Rocket. I'll try designing the rocket in that software and see what the descent speed is under a streamer or streamers.

Seems like I was able to use Rocksim to determine the streamer descent speed a year or so ago by entering the actual streamer dimensions, but I can't seem to replicate the result.

I got pretty close by entering the streamer's dimensions in Rocksim for a few of my projects. If you post the file, perhaps I could take a look and see what the issue is...


Later!

--Coop

Played with Rocksim again and this time I got it to take my streamer dimensions and give a descent speed. At least in my version of Rocksim, there are only four pre-listed streamers. Not all of them seemed to allow me to change their dimensions and also give me a descent speed.

A little different project this time- at apogee (about 2,000 feet per Rocksim), the camcorder section and rocket section will separate and descend on their own small drogue chutes (or streamers). Each will have its own altimeter, which will fire the main chute for each at 400 feet and 300 feet respectively. Curious to see if I can keep the rocket section in view of the camcorder during descent, since the streamer or drogue chute selected for the rocket section will allow the rocket section to descend slightly faster than the camcorder section.

TTRA launch next Saturday at Plant City FL- check out Youtube on Sunday- search for jmomenee for all my onboard videos, including this new one. L3 cert flight in February with a different rocket.

jmmome said:

A little different project this time- at apogee (about 2,000 feet per Rocksim), the camcorder section and rocket section will separate and descend on their own small drogue chutes (or streamers). Each will have its own altimeter, which will fire the main chute for each at 400 feet and 300 feet respectively. Curious to see if I can keep the rocket section in view of the camcorder during descent, since the streamer or drogue chute selected for the rocket section will allow the rocket section to descend slightly faster than the camcorder section.

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Definitely post a link here to your results - that would be a cool video.

Here's the link to my Youtube video from Saturday's TRA flight: https://www.youtube.com/watch?v=vHapXyFey8o

Interesting result from the flight for this 3" diameter Blue Tube, 70" long rocket powered by an Aerotech I300 motor. Had an HD camcorder pointing down on the 39" long camcorder section, which had a tailcone so that it was streamlined. The rocket body section had a keychain camcorder pointed up in hopes of seeing the camcorder section during descent (it did for a few frames just after separation). Both had two streamers- the same sized 70" x 5" and 40" x 4" streamers as drogues.

Not too unexpectedly, the camcorder section descended like a lawn dart at an average speed of 92fps during drogue descent, while the rocket body section descended sideways much of the time and had an average descent speed of 55fps. I used VCL Media Player for each onboard video to determine how many seconds elapsed between the drogue charge firing, which separated the two sections, and the main charges (each section had its own altimeter). If I can assume the altimeter was accurate as to apogee altitude, and that the main charges fired at the preset altitudes, then it was pretty straightforward to calculate the average descent speed for each.

Probably the coolest part of the flight was that, after the camcorder section touched down and was laying in the cow pasture grass, about 10 seconds later you can see the rocket body section descending under streamers and main parachute in the distance (they landed maybe 200 yards apart).

As I expected, the video from the camcorder section was oriented straight down during drogue descent with no pendulum motion(nice view of the parked vehicles for a couple of seconds), while the video from the rocket body section was a combination of horizon and sky as the rocket body descended in a mostly horizontal position but rocked wildly.

And both sections/ camcorders lived to fly another day. I'll try small drogue chutes next time with the intent of having the camcorder section descend more slowly than the rocket section.