Estes Recovery Formula?

Ok, I did a quick search and didn't find anything on this topic sooo...Does Estes have an actual formula for determining which size 'chute/streamer to use? Or are these guys just flipping a coin? (Note: I haven't launched a rocket in about 20 years and I am just now getting back into it. Way back when there there seemed to be a bit more rhyme and reason to it.)

Here's why I ask: I just bought an Alpha III and a BLU-97b cluster bomb and BOTH came with a 12" chute inspite of the fact that the Alpha weighs about 1.2 oz which is about 1.9 oz. lighter than the cluster. Needless to say, after watching it drift over 150 yards in calm conditions with a B motor, I have replaced that silly chute in the Alpha with a streamer.

In their 2005 catalog, the Sizzler is a mere 0.8 oz and reportedly flies to altitudes of over 2000' and that uses a 12" 'chute as well. So I guess if you plan on using a c6-3 in that thing you'll find it 3 miles away with a mighty 0.1 mph breeze blowing. Yet the Star Dart weighing in at 0.82 oz uses a streamer.

The ONLY difference is the fin configuration. The Sizzler is a tad pointier. But that logic doesn't work with the Firestreak because it has pointy fins, uses a streamer and wieghs in over .8 oz.

What sort of sourcery do they use to determine recovery?



-DAllen

The star dart has a streamer? When I got it, it came with the 12" chute.

They probably got too many complaints about it getting lost. I think Estes uses chutes as much as possible, like it isn't a rocket without a chute. I also think thet they like their rockets to come down slowly. Most of their recovery devices are too big (with the exception of the Mini Meanie, where the streamer is too small to do anything and the rocket breaks on almost every landing). Actually, the SpaceShipOne uses a 12" chute, which is just a little small. They need some intermediate chute sizes, like 9" and 16".

Do any rockets besaides the Executioner use a 24" chute?

Uses a 24", and there may be others, phenix might of to. I think they do make an 18". If you are just starting out consider some thin mill top flight chutes, will last you forever and are so nice you could use them in multiple rockets, they are like the standard chutes but made thinner so they pack well in smaller rockets.

The Mean Machine uses a 24" - far too big. I use an 18" on mine - works fine, and a lot less walking on an F24 (great motor).

Originally posted by DAllen
What sort of sourcery do they use to determine recovery?

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What matters most is what you use yourself. I recommend RockSim

download a free demo here.

Originally posted by Apogee
What matters most is what you use yourself. I recommend RockSim

download a free demo here.

Click to expand...

No way!

Originally posted by Apogee
What matters most is what you use yourself. I recommend RockSim

download a free demo here.

Click to expand...

Wow...that is positively SHOCKING to hear that from someone that works at Apogee Sorry, just giving you a hard time...I just don't understand why a big 'ol company like Estes wouldn't have this silly issue figured out before selling it to me.


-DAllen

I think I've figured the Estes recovery device formula...

high altitude + oversize recovery device = long distance drift

long distance drift - willingness to travel a mile to recover modroc (or visual loss of modroc) = lost modroc

lost modroc + BAR with too much time on their hands + money burning a hole in said BAR's pocket = ANOTHER MODROC KIT $OLD!

cha-ching!

estes eliminator uses both 12 or a 24" chute. at the option of the builder. a 12" chute is too big, a 24 inch chute is WAAAAY too big.

Originally posted by KevinK
I think I've figured the Estes recovery device formula...

high altitude + oversize recovery device = long distance drift

long distance drift - willingness to travel a mile to recover modroc (or visual loss of modroc) = lost modroc

lost modroc + BAR with too much time on their hands + money burning a hole in said BAR's pocket = ANOTHER MODROC KIT $OLD!

cha-ching!

Click to expand...

Heh...Sadly Kevin, I think you are onto something there. I believe there might be another component to that equation:

Too many kits of one kind in stock = kits that get 'chutes 2x bigger than necessary.

Where's the Estes rep in TRF to answer these questions?

-DAllen

Slightly less cynically, I'd guess that Estes' logic goes something like this:

Streamer or small 'chute -> rocket gets damaged, their fault -> you get a free rocket under warranty.

Large 'chute -> rocket gets lost, your fault for launching in too small an area or too strong a wind -> you buy a replacement rocket.

Large 'chute, which you replace with smaller 'chute or streamer -> rocket gets damaged, your fault -> you can't claim a free warranty replacement so you buy a replacement.

Summary: if they supply a streamer or small 'chute, it costs them money. If they supply a large 'chute, it earns them money. Nor is it any sort of cynical conspiracy. It's Estes' job to make sure the rocket doesn't damage itself. It's your job to decide when/where you can fly it and expect to get it back, or if the ground is soft enough that you can get away with a smaller 'chute.

Talk about big chutes, the Estes Prowler came with a 24" which was WAY too big for a light rocket like that. I always fly it on 12" chutes myself. As for intermediate chute sizes, Estes used to make a 10" chute for their "Mini-Brutes" back in the eighties.

As a rule of thumb, if the fins are swept back behind the rocket, they're more likely to break on landing with a streamer so I'll generally use a chute unless the rocket's obviously too light to use one. Depends on the winds too. Frankly, I'd rather fix a broken fin than lose the rocket.

Originally posted by adrian

Summary: if they supply a streamer or small 'chute, it costs them money. If they supply a large 'chute, it earns them money. Nor is it any sort of cynical conspiracy. It's Estes' job to make sure the rocket doesn't damage itself. It's your job to decide when/where you can fly it and expect to get it back, or if the ground is soft enough that you can get away with a smaller 'chute.

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True, I see what you are saying BUT refer back to my original post. My whole original beef is there is no (apparent) consitant system of recovery method. I wouldn't be complaining if ALL the kits had over-sized chutes but that's not the case. Call me a whiner if you must but when I buy a kit, this garbage ought to be figured out for me.

Hmmm...Quest kits (among others) are starting to look like a good idea...

-DAllen

I have never seen a quest parachute open in my life, flis, havent used them yet, estes open enough but for a very nice chute go with a thin mil top flight chute.

Originally posted by DAllen
What sort of sourcery do they use to determine recovery?

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Parachute Size Calculator





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Originally posted by Mike_BAR
Parachute Size Calculator
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That's really amusing. I ran the calcs for the cluster bomb in question (3.2 oz.) and it told me I should have a 13 to 17 inch chute and guess what came with the kit?! A 12" chute - not bad actually. But the Big Bertha I just bought weighs in at 3.0 oz per the packaging and what does it have? An 18" chute!



I'll bet that parachute calculator ain't the formula Estes uses. Maybe they have a giant roulette wheel in their board room to figure it out. Who knows...

I am done being anal-retentive about this topic and annoying the community with my jackassery. From now on, I am just going to plan on spending a few extra bucks to replace whatever recovery system Estes has in their kits with something reasonable or just buying kits from someone else.

Sunward kits aren't looking too bad either come to think of it...

-DAllen

Fin design effects needed descent speed...

Originally posted by DAllen


I'll bet that parachute calculator ain't the formula Estes uses. Maybe they have a giant roulette wheel in their board room to figure it out. Who knows...

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DAllen,

I missed that you were asking how Estes calculates parachute sizes for their models. I guess only Estes designers know for sure, though you may be correct about the giant roulette wheel.

The parachute calculator does a fair job at calculating an appropriate chute size for a model rocket. Others have mentioned safe decent rates of 10 - 15 feet per second or even 15 - 22 feet per second. You will find a few interesting message threads if you do a quick search of "decent rate" at TRF.

For what it is worth, the 15 fps sounds good to me, for most all low-powered rockets.

Regards,
Mike

If I get around to it, I might make a calculator similar to that, but where you can choose the descent rate. Unfortunately that is not javascript, so it will be a little harder.