Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > The Golden Age of Model Rocketry > Model Rocket History
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 09-25-2016, 01:04 AM
Initiator001's Avatar
Initiator001 Initiator001 is offline
Too Many Initiators is Never Enough
 
Join Date: Mar 2005
Location: San Diego, CA
Posts: 1,937
Default B6 vs. B14 motor

There have been past threads on YORF discussing the B14 motor.
While there is little if any likelihood of this motor ever being put back into production it's performance has many an 'olde-tyme' rocketeer becoming misty-eyed when remembering the performance of the B14.

I had the opportunity at NARAM-58 this past July to perform an un-scientific experiment comparing the B14 motor with a current production B6 motor. A rocketeer was selling off a quite substantial collection of 'old' rocket motors at NARAM and I made arrangements to pick up all the B14 motors he was selling.

Most of the packs were B14-0 motors but there was a package of Centuri B14-5 motors dated '3-26-73'.

I had brought with me an Estes RTF SkyTrax model. This rocket had a clear payload section into which I placed a current model Jolly Logic Altimeter Two. I would fly the model first with a current Estes B6-4 motor and then a second flight with the Centuri B14-5 motor. The only changes to the SkyTrax model was drilling holes in the payload section so the Altimeter Two could sample the atmosphere and a screw to retain the nose cone on the payload section.
Attached Thumbnails
Click image for larger version

Name:  Estes SkyTrax with JL2 Altimeter.jpg
Views: 46
Size:  60.4 KB  
__________________
Bob
S.A.M. # 0014
Reply With Quote
  #2  
Old 09-25-2016, 01:09 AM
Initiator001's Avatar
Initiator001 Initiator001 is offline
Too Many Initiators is Never Enough
 
Join Date: Mar 2005
Location: San Diego, CA
Posts: 1,937
Default

First up was the Estes B6-4 motor with a date code of 'A1108101'.

The motor ignited promptly and the flight was without incident.

Data from the Altimeter Two:

Apogee: 166'

Top Speed: 66 MPH

Burn Time: .92 seconds

Peak Acceleration: 7.1 G

Ave. Acceleration: 3.3 G

Coast to Apogee Time: 2.8 seconds
Attached Thumbnails
Click image for larger version

Name:  NARAM-58 SkyTrax launch with B6-4 motor.jpg
Views: 22
Size:  45.5 KB  
__________________
Bob
S.A.M. # 0014
Reply With Quote
  #3  
Old 09-25-2016, 01:17 AM
Initiator001's Avatar
Initiator001 Initiator001 is offline
Too Many Initiators is Never Enough
 
Join Date: Mar 2005
Location: San Diego, CA
Posts: 1,937
Default

Next on the pad was the SkyTrax with the Centuri B14-5 motor.

Liftoff was a blur with an otherwise uneventful flight and recovery.

Data from the Altimeter Two:

Apogee Altitude: 191'

Top Speed: 81 MPH

Burn Time: .64 seconds

Peak Acceleration: 19.8 G

Ave. Acceleration: 5.8 G

Coast to Apogee Time: 3.3 seconds

The data clearly show that the B14 subjected the SkyTrax to over twice the acceleration of the B6 motor.

Cool!

I still have a few B14-3 and B14-5 motors plus about a dozen B14-0s.
Hmmm...
Attached Thumbnails
Click image for larger version

Name:  NARAM-58 SkyTrax launch with B14-5 Motor.jpg
Views: 38
Size:  106.0 KB  
__________________
Bob
S.A.M. # 0014
Reply With Quote
  #4  
Old 09-25-2016, 03:08 AM
BEC's Avatar
BEC BEC is offline
Master Modeler
 
Join Date: Feb 2009
Location: Auburn, Washington
Posts: 2,303
Default

Cool!

I'm a bit surprised at the burn time, though. I distinctly remember that the quoted burn time for the B14s - at least back in the late 1960s, was 0.35s.

That's what I see in some old catalogs online as well.

Hmmmmmmmmmmmm
__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE
Reply With Quote
  #5  
Old 09-25-2016, 08:06 AM
mojo1986's Avatar
mojo1986 mojo1986 is offline
Master Modeler
 
Join Date: Mar 2005
Location: Kingston, CANADA
Posts: 1,656
Default

Quote:
Originally Posted by BEC
Cool!

I'm a bit surprised at the burn time, though. I distinctly remember that the quoted burn time for the B14s - at least back in the late 1960s, was 0.35s.

That's what I see in some old catalogs online as well.

Hmmmmmmmmmmmm


Bernard, I wonder if it's the way the data is interpreted. Estes did exhaustive tests on all of their motors back in the day. They may have had a way to estimate the point at which all of the black powder fuel was consumed from their data, or it could have been as simple as knowing the burn rate of the fuel and the configuration of the grain in the motor.

Initiator's altimeter is probably reporting end of burn time as the point at which acceleration goes to zero (in other words, roughly when all propellant gases have escaped through the nozzle). These things aren't necessarily the same thing, and it's reasonable that Initiator's estimate of burn time would be higher.
Reply With Quote
  #6  
Old 09-25-2016, 03:32 PM
tbzep's Avatar
tbzep tbzep is offline
Dazed and Confused
 
Join Date: Mar 2005
Location: TN
Posts: 8,712
Default

There may be some trailing thrust before it gets to the delay as stated by Mojo. The core doesn't go all the way to the top of the grain and could have enough thrust to be recorded for an extra few fractions of a second. As an extreme example, the A10 shows an extremely long low thrust event after a very large initial spike.
__________________
I love sanding.
Reply With Quote
  #7  
Old 09-25-2016, 03:44 PM
georgegassaway's Avatar
georgegassaway georgegassaway is offline
Contest, Sport, it's all good......
 
Join Date: Jul 2008
Location: Homewood, AL
Posts: 380
Default

I saw and used some Estes B14ís in 1970-71. Neat motors but I preferred C6ís when I wanted more than a B6.

But for contest flying I did use a few Centuri B14ís around 1973. They SUCKED. Did not perform at all like the old Estes B14 from years before. IIRC a 2-stage egglofter of B14-0 to B4-6 took off more like a B4-0 booster (no typo, I do mean it did not even seem to take off as fast as a B6-0 would have).

Having found out later about at least one explosion at Estes during B14 core drilling, killing a worker, I wonder if the Centuri B14ís of that time period (1973-ish) were either not drilled or otherwise made differently to avoid the drilling. Obviously they were made on the same machines as Estes but they definitely did not perform like the 1970-era Estes B14. I also do not think the later Estes B14ís performed the same, either.

So, I think your test is too much Apples and Potatoes.

A really good test would be an old 1970-ish Estes B14 vs B6 of the similar time period, or at least an old Estes B14 since the B6 has not changed too much in thrust profile over the years.
__________________
Contest flying, Sport flying, it's all good.....
NAR# 18723 NAR.org
GeorgesRockets.com
Reply With Quote
  #8  
Old 09-25-2016, 03:51 PM
tbzep's Avatar
tbzep tbzep is offline
Dazed and Confused
 
Join Date: Mar 2005
Location: TN
Posts: 8,712
Default

George, now that you mention it, I've seen B14 comparisons where the nozzles are not the same size and different core depth, with later production looking a lot like the B8. I believe the consensus was they quit drilling and started making something like the B8 before Estes ever released the B8 by name.
__________________
I love sanding.
Reply With Quote
  #9  
Old 09-25-2016, 05:39 PM
BEC's Avatar
BEC BEC is offline
Master Modeler
 
Join Date: Feb 2009
Location: Auburn, Washington
Posts: 2,303
Default

This conversation has gone where my thoughts went last night when I saw Bob's posts....that the "B14" from 1973 might have been more like the B8s.

Heck, I have a few B8-5s. I should conduct exactly the same experiment (though I might use an AltimeterThree so as to get the data graphs) as Bob did. I could even use a Skytrax - I have one.
__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE
Reply With Quote
  #10  
Old 09-25-2016, 06:29 PM
hcmbanjo's Avatar
hcmbanjo hcmbanjo is offline
When Pigs Fly!
 
Join Date: Sep 2005
Location: Orlando, FL
Posts: 922
Default

Quote:
Originally Posted by tbzep
George, now that you mention it, I've seen B14 comparisons where the nozzles are not the same size and different core depth, with later production looking a lot like the B8. I believe the consensus was they quit drilling and started making something like the B8 before Estes ever released the B8 by name.


I remember this change too!
__________________
Hans "Chris" Michielssen
Old/New NAR # 19086 SR

www.oddlrockets.com
www.modelrocketbuilding.blogspot.com
http://www.nar.org/educational-reso...ing-techniques/
Your results may vary
"Nose cones roll, be careful with that."
Every spaceman needs a ray gun.
Look out - I'm the Meister Shyster!
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 03:41 AM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2018