Upgrading drogue

[smstachwick]

In the process of simming modifications for a WildMan Darkstar Jr, I've come across a few question marks with regard to recovery.

For flights on lower-end 38mm motors (G and H), I've adjusted the file to eliminate the switch band assembly and forward body tube, as I anticipate dual-deploy will not be entirely necessary while flying under, say, 3000 ft. I have, however, added a mass object to represent a Jolly Logic Chute Release, just to reduce drift. Being unfamiliar with how it works and its effects on post-ejection flight, is it entirely necessary to have a drogue parachute while using this device?

While simulating the stock drogue and main together in the motor eject version, the last simulation I attempted gave me a warning that the main will deploy at high speed (45.1 mph). I've been wondering about the possibility of upgrading to a larger drogue and simulating with that, but I'm not sure how I should go about it. I'm mainly wondering who makes the drogue that comes with the kit, what the next size up is, and if there is a way that I can import it into OpenRocket instead of having to define it manually.

 

[bobbyg23]

No need for a drogue at all with the jolly logic

 

[smstachwick]

No need for a drogue at all with the jolly logic

Good to know. I may end up flying some higher flights in my Star Orbiter that way, assuming I can get the JLCR in a BT-60 without too much trouble.

On the other hand, main deployment at 45mph sounds a bit risky, so I’m thinking that using a drogue (and upgrading from the stock one) might be desirable anyway.

The stock drogue appears to be 30.5cm (12 inches) and consistently produces maximum descent speeds in the low- to mid-40s, which strikes me as a bit small and fast.

 

[manixFan]

I’ve used the JLCR on a wide variety of rocket sizes and have never used a drogue. The bundled chute acts enough like a drogue in my experience. 45mph is about 66fps which is about the typical speed for a drogue anyway. Some of my high flying MD rockets come down drogueless at closer to 80-100fps at chute deployment with no ill effects.


Tony

 

[smstachwick]

I’ve used the JLCR on a wide variety of rocket sizes and have never used a drogue. The bundled chute acts enough like a drogue in my experience. 45mph is about 66fps which is about the typical speed for a drogue anyway. Some of my high flying MD rockets come down drogueless at closer to 80-100fps at chute deployment with no ill effects.


Tony

Thanks. That's reassuring.

Looking at some instructions I found, it appears that the rocket possibly doesn't come with a chute? It hadn't occurred to me that this might be typical in high-power but it makes sense, given how pricey large ones are and how strong flyers' preferences can be.

 

[Handeman]

On the other hand, main deployment at 45mph sounds a bit risky, ...

Any decent chute should be able to handle that speed easily. Skydivers deploy chutes at +120 mph. Our deployments are relatively slow with low loading. Zippering should be a bigger concern.

The simulator may consider 45 mph high speed, but I don't consider it high speed until it's over 80 mph. YMMV

 

[sriegel]

If you're coming down under a drogue, it's common to see 75-90 fps on the airframe. A well-built main can handle that. I had a 6' elliptical canopy on a 10 lb bird deploy at 220 fps after a delay anomoly using motor eject (I know, I know, go DD...). The canopy survived.

 

[mtnmanak]

Looking at some instructions I found, it appears that the rocket possibly doesn't come with a chute? It hadn't occurred to me that this might be typical in high-power but it makes sense, given how pricey large ones are and how strong flyers' preferences can be.

This was from a few weeks ago, so not sure if you already have the kit, but these kits do not come with a parachute. I have a few of these DS Jr 2.1" kits - one built standard, one built minimum diameter and one built for the staging kit. Great fliers.

Most HPR kits do not come with parachutes. Some of the Level 1 cardboard kits like the Apogee Zephyr or the LOC IV come with parachutes, but they aren't very good chutes. I have never bought a fiberglass kit larger than 38mm diameter that included a chute (there may some kits out there, but I have not seen one).

If you are going to get into HPR, I highly recommend you start investing in a catalogue of parachutes. I like to stick with one manufacturer to ensure I have an apples-to-apples comparison between chute sizes. A 30" Fruity Chutes Iris is going to be vastly different than a 30" Rocketman chute. Personally, I use Fruity Chutes Ellipticals for drogues and pilot chutes, Fruity Chutes Iris for main chutes up to 120" in diameter, SkyAngle Cert3's for rockets in the 80-100lbs category and then I have a couple big Rocketman chutes for rockets over 100 lbs.

I am not necessarily recommending those manufacturers, there are some really awesome parachute makers out there, but spending money on good parachutes is not wasted. If you care for them, they will last a long time and having a good catalogue allows you to dial in exactly the right parachutes for the given field and weather conditions at the launch.

Once you get past the 2.1" kits, the kits get more sparse in terms of what you get. By the time you get to the big stuff, it is basically just a box of tubes, fins, nosecone and some Bulkheads/CRs. You will have to provide everything else including hardware, shock cords, parachutes, nomex, harnesses, etc.

The Darkstar kits are really great. I have at least one of every single Darkstar Tim makes (the pictures of the 3" and 4" Darkstars on the Wildman site are my builds) and I have yet to find one that doesn't fly straight and true every time.

 

[smstachwick]

This was from a few weeks ago, so not sure if you already have the kit, but these kits do not come with a parachute. I have a few of these DS Jr 2.1" kits - one built standard, one built minimum diameter and one built for the staging kit. Great fliers.

Most HPR kits do not come with parachutes. Some of the Level 1 cardboard kits like the Apogee Zephyr or the LOC IV come with parachutes, but they aren't very good chutes. I have never bought a fiberglass kit larger than 38mm diameter that included a chute (there may some kits out there, but I have not seen one).

If you are going to get into HPR, I highly recommend you start investing in a catalogue of parachutes. I like to stick with one manufacturer to ensure I have an apples-to-apples comparison between chute sizes. A 30" Fruity Chutes Iris is going to be vastly different than a 30" Rocketman chute. Personally, I use Fruity Chutes Ellipticals for drogues and pilot chutes, Fruity Chutes Iris for main chutes up to 120" in diameter, SkyAngle Cert3's for rockets in the 80-100lbs category and then I have a couple big Rocketman chutes for rockets over 100 lbs.

I am not necessarily recommending those manufacturers, there are some really awesome parachute makers out there, but spending money on good parachutes is not wasted. If you care for them, they will last a long time and having a good catalogue allows you to dial in exactly the right parachutes for the given field and weather conditions at the launch.

Once you get past the 2.1" kits, the kits get more sparse in terms of what you get. By the time you get to the big stuff, it is basically just a box of tubes, fins, nosecone and some Bulkheads/CRs. You will have to provide everything else including hardware, shock cords, parachutes, nomex, harnesses, etc.

The Darkstar kits are really great. I have at least one of every single Darkstar Tim makes (the pictures of the 3" and 4" Darkstars on the Wildman site are my builds) and I have yet to find one that doesn't fly straight and true every time.

Good to know.

I’ve still got a long way to go until I feel ready to attempt certification, my goal is to learn everything I can that might be relevant to building and flying a rocket like that (read: make as many of the mistakes one could make with it as possible) in the low- and mid-power realm before I actually buy, build and fly it.

I’m thinking at least a year until a flight, but it doesn’t hurt to sim a few things now since I have that at my disposal already.

 

[mtnmanak]

Good to know.

I’ve still got a long way to go until I feel ready to attempt certification, my goal is to learn everything I can that might be relevant to building and flying a rocket like that (read: make as many of the mistakes one could make with it as possible) in the low- and mid-power realm before I actually buy, build and fly it.

I’m thinking at least a year until a flight, but it doesn’t hurt to sim a few things now since I have that at my disposal already.

Good plan - if you want a relatively low cost trial entry, grab one of the aforementioned Zephyr's or LOC IV's - they come as complete kits, tons of videos around on how to build them, they are very easy to build, and you can fly them on a good variety of mid-powered motors while you master your HPR skills.

http://www.mountainmanrockets.com/index.php/hpr-primer/