Deployment Speed

On the average Estes rocket (PSII specifically), what is the maximum speed you'd be comfortable deploying your chute at the top?

I've deployed them at around 50 fps.
[video=youtube;3KwayAJUn_E]https://www.youtube.com/watch?v=3KwayAJUn_E[/video]

Without an altimeter, it's pretty much, how accurate can you drill the delay. You certainly can't pick a speed for the deployment. After a number of flights you will get the delay part down and have a better idea of how the rocket behaves in different speed winds with different motors.

I used a Kevlar cord on my Leviathan that extends about 4 - 5 ft out of the BT. Then I tied on the stock elastic shock cord. I've flown it on HobbyLine G to 4g H motors without any problems and I'm sure some of the deployment speeds were above optimal.

Well you can't drill SU delays. That's my issue. But things can be done. I've never drilled a delay before. I ordered the tool but it hasn't arrived yet. Looks like it's learning curve time.

So here's an interesting query. Assuming you can't drill the delay, as which would you prefer to do? Deploy at 42fps while ascending or deploy at 52fps while descending?

Eeek. I wouldn't want to do either. If I could not drill a delay or add electronics to fix either one, I'd get the hardware so I could.


Later!

--Coop

Why can you not drill the delay? You don't need the delay drill tool, just a 3/16th drill bit and a ruler. https://www.aerotech-rocketry.com/c...tions/RDK_Instructions/rms_delay_mod_inst.pdf

Because the particular motor is an AeroTech su motor.

Kruegon said:

So here's an interesting query. Assuming you can't drill the delay, as which would you prefer to do? Deploy at 42fps while ascending or deploy at 52fps while descending?

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Sounds like those motors with those delays are not right for the rocket. Time to select a different motor if you are going to use SU motors that can't be drilled.

Yeah but I'm running into an issue where there is no matching SU motor that I can find. At least it's a work in progress not a finished product.

if I had to chose between deploying early or late...I would prefer to use an adjustable delay how ever a bit early would be my choice for several reasons. one chutes do not instantly inflate, for a 30" chute you're looking at about a second and at air speeds below say 10 - 15 fps they tend not to open. 42 fps and slowing or 57 and accelerating take your pick it is after all your rocket.
Rex

Kruegon said:

Yeah but I'm running into an issue where there is no matching SU motor that I can find. At least it's a work in progress not a finished product.

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Then don't use a SU motor. Seems the logical solution....


Later!

--Coop

My solution for a not done project would be to use the later delay and increase the rocket weight. If that is not an option, I'd still go with a later delay and use a longer shock cord of different material. In my Ventris, I use 1/8" bungee cord due to long delays on a motor that makes people nervous.

Kruegon said:

Well you can't drill SU delays. That's my issue.

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Ummm.....why not?

I've done it & others I know have. It's an old school method. My L-1 was a H-125 single use[I think 125. so long ago...] anyhow drilled down through BP touch hole.
Remove BP...drill delay....replace BP & cap.

Just got to know how to do it accurately.

Coop said:

Then don't use a SU motor. Seems the logical solution....

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Along these lines, the Aerotech loadable motor system (not the reloadable system) are essentially single use motors that you assemble. Most of those, IIRC, can be delay drilled. I was looking at that for some of my applications, where I'm between stock delays. The other benefit is that the LMS motors mostly skirt the hazmat shipping that impacts larger SU motors.

Personally I'd rather pop early.

A few things to remember, the chute is going to take some time to clear itself, in that time the open rocket is going to slow down.

sims are an inexact science. Delays can have a 20% variance. Between those two things, I wouldn't lose sleep trying to get an exact number, you're not going to get an exact result anyways. I fly my Optima on G78-4, and G78-7's.

Get it in the ballpark and light 'er up.

CJ you know how it is now days if its not on Rock Sims it can't be done.

DizWolf said:

Personally I'd rather pop early.

A few things to remember, the chute is going to take some time to clear itself, in that time the open rocket is going to slow down.

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That's the thought I was having. I just wanted to check the hive mind in case I was missing something. MPR and HPR are rather new to me. I don't count 24mm Estes Es as mid power. 29mm on the other hand counts in my book. And I'm starting into 29mm MPR and HPR now with my eyes on 38mm HPR.