AeroTech Delay Cheatsheet

Discussion in 'Propulsion' started by OKTurbo, Aug 31, 2005.

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  1. Aug 31, 2005 #1

    OKTurbo

    OKTurbo

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    Here is something I thought I'd share. It's a one page "cheat sheet" for the AeroTech 24/40 and 29/40-120 hobby motor delays.

    The delays are drawn full scale, so all you have to do is hold the delay grain up to the drawing. You can do a quick check to make sure you have the right length delay, or pick a shorter/longer delay for the motor you're wanting to assemble.

    For example: You have a G64-4W in your stash, but you need a 10 second delay for the rocket you want to fly. If you have a G33-5J reload that you're willing to break up to fly the rocket....use it's delay in the G64 and you're set with a 10 second delay.

    Note that the 24/40 and 29/40-120 delays are the same diameter, but different lengths. The 24mm delays will work in the 29mm, but you'll need to have the right delay spacer.
     
  2. Aug 31, 2005 #2

    shockwaveriderz

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    I don't know but thats why I am asking: are we allowed to use delays from one motor in another motor? Are delays on Hobby motors allowed to be drilled like on HPR motors? I guess the RMS hobby motors don't use those RDK delays?
     
  3. Aug 31, 2005 #3

    OKTurbo

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    I don't know the official answer....This is just my own cheatsheet.

    As far as I know, the hobby delays are the same formula except for the "slow" delays. No, they are not the same as the RDK delays. The formulas may or may not be the same, but dimensionally they are different.

    The official AeroTech press release on drilling of delays does say RDK, but the info that they give on delay lengths include the hobbyline motors, so I'm not sure if drilling of these delays is approved or recommended by AeroTech. Maybe Gary R. will see this and comment.
     
  4. Sep 1, 2005 #4

    MarkM

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    I don't think this is entirely correct. I'm pretty certain you can use delays from other motors, but I always thought they had to be of the same propellent type since the delays burn differently depending on propellent. If this is right, your example would result in an incorrect delay timing since the G64 is white lightening while the G33 is Black Jack...two very different propellents with very different burn rates. But, perhaps I'm wrong on this.
     
  5. Sep 1, 2005 #5

    cjl

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  6. Sep 1, 2005 #6

    shockwaveriderz

    shockwaveriderz

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    can any of the rdk delay units be used with RMS hobby motors?

    I don't understand how a -5J delay will become a 10 sec delay if you put it in the G motor/

    whats a delay spacer?
     
  7. Sep 1, 2005 #7

    OKTurbo

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    cjl,

    That's the chart I used to make up the drawing.

    shockie...the G33-5J is a BlackJack motor and burns much slower than the G64-10W White Lightning motor. Don't forget that the delay element starts burning at motor ignition also. The delay burns much faster due to the pressure in the motor as the propellant grains burn, then the delay burn rate slows down during coast.

    The delay spacer is the small cardboard tube/spacer that you put in with the delay grain...unless the delay grain is full length like the G33-5J. The delay part of the motor consists of an o-ring, the delay liner/insulator, the delay grain, and the delay spacer (if needed).

    Hope that makes sense. There are some good drawings of the assembled AeroTech motors on their website.
    http://www.aerotech-rocketry.com/customersite/resource_library/AT_rms_assy_dwgs.html

    No...the RDK delay grains are a different diameter and cannot be used in the hobby line motors
     
  8. Sep 1, 2005 #8

    bobkrech

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    Bob
     
  9. Sep 1, 2005 #9

    Rocket Guy 1317

    Rocket Guy 1317

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    I have switched Delay before. I had a F40-7 and a G64-4 so swapped delays and made it a G64-7 and an F40-4.
     
  10. Sep 1, 2005 #10

    shockwaveriderz

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    thanks for the responses guys....I apprecaite it!
     
  11. Sep 1, 2005 #11

    OKTurbo

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    So now that you understand what I was going for, is the cheat sheet useful?

    Maybe it would sound better if I called it the "AeroTech 24/29 Hobby Line Delay Grain Matrix". :D
     
  12. Nov 12, 2005 #12

    shockwaveriderz

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    This thread has been dormant for a while but after doing some thinking I now have some additional questions:

    for example lets look at a F12J has a delay length of .625" (20/32) with delays of 3 (std) and 5 slow.

    Questions:

    1. Can any delay/delay spacer conbination used as long as the length og the dealy/delay spacer equals .625" in length?


    2. WHat is I wanted a F12J with a longer delay than 3 or 5? What kind of delay would I get if I used a 10 sec delay from another motor? a F40-10T or D15-10W or a F52-11T ?

    I obviously an trying to figure out to mix and match different delays to get custom delays times....

    For example if I used any of the above delays , what kind of actual delays would I end up with?

    I am also looking for math formulas so that if I decide to use a delay from one motor I can calculate its delay in the new motor.


    tia
     
  13. Nov 13, 2005 #13

    OKTurbo

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  14. Nov 13, 2005 #14

    troj

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    One thing to be aware of is the scaling that happens when you print.

    Depending on how close two delays are in length and the scaling your driver does, you may end up thinking you have one delay when you truly have another.

    Before relying on such a printout, spot-check your copy for accuracy using know delays or you may cause yourself problems.

    -Kevin
     
  15. Nov 13, 2005 #15

    shockwaveriderz

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    ok: ok lets see if I got this right. The largest delay train/delay spacer combo for the F12 would be.625".

    Lets say I wanted to use the slow -10 delay from the D13 that is .500 in length then I would need a .125" length delay spacer?

    also since the thrust duration of the d13 is 1.5 sec, the math would be:

    thrust duration + delay Time = 1.5 sec + 10 sec = 11.5 sec total delay time .

    to determine the burn rate of the .500 length delay .500/11.5 = .0435" per sec delay burn rate



    The thrust duration of the F12 is 3.6 sec ... so if i multiply 3.6 x .0435 = 0.1566 " of the delay train will be used during the thrust duration.

    If i then subtract 0.1566 from .500 = 0.3434 " delay length left

    If I divide that by .3434/ .0435 = 7.89 sec delay time.

    so I almost get a F12-8 ????? rounding off...

    by the way does anybody have an idea what the At delay train composition is? If its not cool to post that kind of info here please email me direct. tia

    Somebody want to check my math?
     
  16. Nov 13, 2005 #16

    OKTurbo

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    Is there a 10 second delay available for the D15 RMS24/40? It's not shown in the current AeroTech catalog.

    edit***nevermind. I see that you were talking about the D13 for the 18/20 motor.

    Careful....there is one major error in your calculations. You can't just add the burn time and the delay time. The delay grain burns faster when the motor is under pressure....and to complicate it more, the pressure changes during the burn.

    You will have to calculate how quickly the delay grain burns for each propellant type AND each motor since even the same propellant types may have different thrust/pressure/nozzles.

    With the two delay types (Standard and Slow) the longest delay you can get with the F12 is 5 seconds after propellant burn out since it uses the full length of the delay cavity with the slow delay material.

    The chart is simply to show what other motors in the lineup have the same delay sizes. If the pdf file is printed out without any scaling (Page scaling = NONE) the delay lengths will be actual size.
     
  17. Nov 13, 2005 #17

    shockwaveriderz

    shockwaveriderz

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    ok: well double poop!...

    SO now i have to take into account pressure too huh> now how the heck would I be able to do that comparsion between motors?

    also I noticed the AT dadatsheet shows the thrust duratuion of the f12 as 3.6 sec while the www.thrustcurve.org actual test date shows it at 2.93......


    so even if i can figure out a way to introduce pressure I still have to use real versus manufacturer numbers..... and of course the number can be somehwhere in between too....
     
  18. Oct 18, 2019 #18

    John Taylor

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  19. Oct 18, 2019 #19

    John Taylor

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    Sorry to double post. Anybody know the measured delay element length for a G76-7 It states it is a HDK-25.
    I need to know the length please, I have a launch tomorrow. I have a G76-4 now and a supply of different elements and spacers.
    I realize of course realize I will have to use the correct spacer to make it flush.
     
  20. Oct 18, 2019 #20

    Rocketjunkie

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    Here's all the Aerotech HDK and RDK sizes. HDK/RDK number, length, and the motors it's used in. Slow is a different formulation. Do not assume a 1/32" per sec burn rate.

    Aerotech delay kits, Hobby line style
    HDK KITS for 18mm Motors
    HDK-01 .281 D24-4T
    HDK-02 .375 D24-7T
    HDK-03 .407 D13-4W
    HDK-04 .469 D24-10T
    HDK-05 .500 D13-7W
    HDK-06 .500 slow D13-10W

    HDK KITS for 24mm Motors
    HDK-07 .344 D15-4T E28-4T
    HDK-08 .407 D9-4W F39-6T
    HDK-09 .438 D15-7T E28-7T
    HDK-10 .500 D9-7W F39-9T
    HDK-11 .531 E18-4W F24-4W
    HDK-12 .625 E11-3J E18-7W F12-3J F24-7W
    HDK-13 .625 slow F12-5J

    HDK KITS for 29mm Motors
    HDK-14 G71-4R
    HDK-15 .375 E23-5T G76-4G
    HDK-16 .406 F52-5T G71-7R
    HDK-17 .500 E23-8T F52-8T F40-4W G71-10R G33-7J
    HDK-18 .531 F52-11T G64-4W
    HDK-19 .562 E16-4W G76-10G
    HDK-20 .657 G64-7W G33-10J
    HDK-21 .657 E16-7W F40-7W G64-10W
    HDK-22 .750 F22-5J F40-10W
    HDK-23 .750 slow F22-7J
    HDK-24 .750 G33-5J
    HDK-25 G76-7G

    Aerotech delay kits, High power style
    RDK01 .314 G77-4R/LMS, G77R-S, H238T-S, H220T-S
    RDK02 .375 G79-4W/LMS, F62T-S, F62T-S, G104T-S, H165R-S, H210R-S, H268R-S
    RDK03 .438 G79-7/LMS, F37W-S, G54W-S, G79W-S, H128W-S, H180T-S, I200W,S
    RDK04 .469 F20-4W/LMS, F62T-M, G77R-M, G104T-M, H238T-M, H220T-M
    RDK05 .563 F20-7W/LMS, F37W-M, G54W-M, G75J-S, G79-M, H128W-M, H97J-S, H180W-M, I200W-M
    RDK06 .594 F62T-L, G104T-L, H238T-L, H220T-L, H165R-L, H210R-L, H268R-L
    RDK07 .656 F37W-L, G54W-L, G79W-L, H128W-L, H180W-L, I200W-L
    RDK08 .719 G75J-M, H97J-M
    RDK09 .406 G67R-S, H242T-S, I357T-S, I300T-S, I435T-S, H148R-S, I218R-S, I285R-S, I366R-S, J420R-S
    RDK10 .469 H242T-M, I357T-M, I300T-M, I435T-M, I600R-M
    RDK11 .500 G61W-S, G67R-M, H123W-S, I161W-S, I211W-S, I284W-S, J350W-S, J570W-S
    RDK12 .594 G61W-M, H123W-M, H242T-L, I161W-M, I211W-M, I357T-L, I300T-L, I284W-M, I435T-L, J350W-M, J570W-M
    RDK13 .625 I195J-S
    RDK14 .656 H73J-S, H112J-S, I154J-S, H148R-L, I218R-L, I285R-L, I366R-L, J420R-L
    RDK15 .719 G61W-L, H123W-L, I161W-L, I211W-L, I284W-L, J350W-L, J570W-L
    RDK16 .781 H73J-M, H112J-M, I154J-M, I195J-M
    RDK17 .531 H148R-M, I218R-M, I285R-M, I366R-M, J420R-M
    RDK18 .500 G77-10R/LMS, G77R-L, H165R-M, H210R-M, H268R-M
    RDK19 G77-7R/LMS
    RDK20 G79-10W/LMS
    RDK21 .432 J460S,J800S,K1100S
    RDK22
    RDK23 .547 J460M, J800M, K1100M
    RDK24 .593 J180S
    RDK25 .616 J275S, J415S, K550S, J540M, K695M
    RDK26 .639 J460L, J800L, K1100L
    RDK27 .685 J180M
    RDK28 .708 J275M, J415M, K550M
    RDK29 .761 J315L, J460X, J540L, J800X, K695L, K1100X
    RDK30 .778 J180L
    RDK31 .803 J275L, J415L, K550L
    RDK32
    RDK33
    RDK34 1.014 J90S, J135S, K185S
    RDK35 1.106 J90M, J135M, K185M
    RDK36 1.175 J90L, J135L, K185L
    RDK37 .524 J540S
     
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