Parachute Vent Holes

[1tree]

Ok, so now I am going to sound wimpy or something. But I am tired of my low power rockets taking such a long journey floating down from the heights. In reading various places I have seen mention of cutting a vent hole in the parachute.

This makes a lot of sense to me. I had been thinking of switching to using streamers for the rockets since they don't go nearly as far anyway. But the thing that I am not sure of is how big of a hole to cut?

I don't know how heavy most of my rockets are, but they are all pretty small. In fact, half launch up decent with a 1/2A3-4T motor.

Along the lines, do most people buy a scale for the purpose of weighing their rockets? (Or simply rely on the kit manufacturer to tell them?)

[fyrwrxz]

Once you get into a little larger birds, a scale becomes almost a requirement. Folks tend to build a little heavier than the 'Pros' do that manufacture the kits. Having said that,there are a number of parachute size/descent calculators available on the net. It's good to have an all up mass for your bird and most should be calculated with the empty casing in place (that what's coming down, right?). So vehicles that are fairly light and can withstand higher impact speeds and some lucky guys can recover on grass or plowed fields. A good rule of thumb is about 15 fps fall speed but YMMV depending on fin arraingements, recovery harness, etc. Start small on the spill hole- you can't add it back in ya know! This reduces the effective lift of the chute but it really serves to ruin the airflow over the canopy which is trying to act like a wing and generate lift over the curved surface as it 'flies' downwind. Straight smoke and good chutes to ya!

[New Ocean]

Many times, these vent holes are just to increase stability (fewer oscillations) and I think they can actually INCREASE drop time if they are the right size. If the spill hole is too big, the 'chute will probably fail to work.

I would suggest streamers in any rocket that is small enough. They are just so much better : ) If your rocket is light/strong enough, go streamer. You can also make your own small parachutes, I have made 'chutes as small as 2 inches for tiny rockets, and they seem fine. So typically I wont modify a 'chute, rather I will make or use a smaller one, or go streamer. After years in the hobby, ive wound up with too many 'chutes (around 25 from 4 inches to 36) and that usually means one will be just right for a given flight.

You could make a really neat X form 'chute for a small rocket by joining two lengths of plastic streamer material. It would be something like a 4 inch 'chute, but it calls for 8 full shroud lines!

There are a few experts in the forum who know a ton about the topic, they will certainly have good feedback.

[[POW]Eagle159]

On some of mine I cut huge holes...a 12'' chute with a 5'' hole, 16'' chute with a 6'' hole. They still work perfect and are easier to roll up cause there is less there.

[luke strawwalker]

There's nothing wrong with streamers... they're probably at least as reliable as chutes if not more so, especially on small rockets...

If you're getting too much drift, you're probably better off with a smaller chute or if you're already down to say an 8 inch chute, you're better off switching to a streamer... I think parachute deployment reliability falls off pretty fast when you get below 8 inch size, though I don't have figures to back it up.

You can do spill holes, but on small chutes it really complicates getting a clean deployment and construction of the chute...

Good luck! OL JR

[Petamocto]

Reviving a dead thread here, but I am at this point myself. I find that in the area I have and the relatively small (C-D) rockets I'm using, the parachutes that come with them seem to be overkill. I guess maybe not if they were landing on a parking lot, but mine have always been fine landing on grass even when the parachute didn't fully deploy.

I don't think I'll go to a streamer on my V2, but I'll certainly be cutting a big spill hole in the parachute. The Vector Force may be getting a streamer, though. The thing is long but so skinny that I have no choice but to wrap the parachute really tightly to get it to fit. I'll maybe try one flight with a spill hole in it first, but if it is still drifting super far I'd go to a streamer.

Worst case scenario I'll have to glue a fin back on, which is a lot better than deforesting the park at the rate I'm going now.

[Devontmp]

On almost all my Estes rockets ,I have droped down one size(18" to 12"- 24"to 18") and have not had any problems.Most LPR companies put
in chutes too big to make softer landings to compensate for consumer inexperience building skills. I built my first Eetes kit when I was 10 yrs old.My skills were bad then(not much better 42 yrs later).Put a lot of fins back on back then. So down size your chutes if possible or go streamer.

[Handeman]

On some of mine I cut huge holes...a 12'' chute with a 5'' hole, 16'' chute with a 6'' hole. They still work perfect and are easier to roll up cause there is less there.

Same here. I have a couple of 12" chutes with 5" holes for windy days.

[Micromeister]

Ditto to most of what the other posters have typed:
The size of the hole depends on the model & weather conditions on the field at flight time.
As Luke mentioned there is Nothing at all wrong with switching to a Streamer with the surface wind speed gets up in the 15-20mph range.

As far as Hole sizes: Generally I'll put a 3/4" Spill hole in 12 to 18" chutes, 7/8" or 1" in 24 to 42". but also have "specials" in most common sizes 12", 18" and 24" parasheets with holes of various size from 2" to 8". I have a Spot Landing 12" chute with a 9" hole that works like a dream

Personally I carry a baggie of different size and length streamers as well as several different size Parachutes, parasheets and X-form chutes to quickly switch out to fit the field conditions. Hand held wind meters and a small scale are also always part of my range box range equipment to make the day a lot more enjoyable.
it is a very good thing to know what your models lift-off mass is as well as the wind speed. If you've sim'ed or calculated the expected altitiude of your models it's also pretty easy to determine how far it will travel with a simple drift rate calculation which can help select the best recovery combination for that flight. This is a scientific Hobby so it is not unreasonable to do the math to know what your model will likely do before sticking a motor in it and see Where it goes.

[DaveCombs]

My solution to this problem is to get a series of ripstop nylon chutes (Top Flight Recovery makes good ones) in different sizes, and I put the appropriate size in the rocket based on conditions. Gather the strings into a locking-style snap swivel and you can exchange them between your rockets in a matter of seconds.

In the rockets you have that don't have enough room for a parachute, use a similar set of streamers of different lengths.