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FSI F7-4 - Info?
#1
I have friend and fellow rocketeer that recently came across five or so Flight Systems Inc. F7-4 rocket engines Mfg. June 1982 and I am wondering, what is the consensus on these motors?  Should the motors be used?  Are they safe (I think they probably are, but just to be safe...)?  Do they have any historical or any other significance other than that FSI is (Or was.) out of business meaning they are OOP?

Here are some pictures... (Never saw it, never happened, eh?Tongue)

   
   
   
   

Sorry, a little blurry, they were taken with my phone.

Fyi, I have posted this on TRF as well.
BuiltFromTrash
First RMS Flight: June-17 2015
Pringles Can Rocket
G53-FJ-7 (29-40/120) 92 Newton-Seconds
~1300 Ft
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#2
One big factor is how they have been stored. If they have had temperature cycling, then you probably should use a rocket you care nothing about to fly one!  I've used motors over 30 years old and had normal flights, but they have been stored in my cool, dry basement since purchase.

I have some Centuri B14 and C5 motors from the 70s, but I'm not the original buyer, so I'm not sure if they will have issues.  I've built a few throw away rockets for testing!
Lee
NAR 55948, L2
In Build:   Estes Saturn 1B
Next: complete Semroc Mars Lander, upscaled Orbital Transport
In Finishing:  Interceptor-E 
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#3
Agree with Trident. Since they are NAR certified, probably safe. But if they have been stored incorrectly, watch out.
John S.
NAR #96911
TRA #15253
MDRA
Level 1, 2014-Mar-15 -- Aerotech Sumo, H133BS
Level 2, 2014-Jun-21 -- Giant Leap Vertical Assault, J240RL
Level 3, 2016-03-12 -- MAC Performance Radial Flyer, M1101WH, 13,028 feet
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#4
They are stamped NAR certified, but are not on the combined list of certified motors.
http://www.nar.org/SandT/pdf/CombinedMot...mpulse.pdf
IIRC they would only be able to be flown at a research launch, and definitely heads up.
Dave Greger L3
NAR# 95846
MDRA #65

Hollie L1
NAR# 99687
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#5
The NAR allows for old certified motors to be flown at NAR launches they just want a heads up before hand and a report afterwards.
http://www.nar.org/wp-content/uploads/20...rogram.pdf

The nozzle photo is grainy, does it look that bad IRL?


Bill Clune L3 | NAR#88583
Been a launch Director
Founded a Club
MARS Club|SRC|MDRA - Forever
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#6
Naw. It was taken with a phone camera and I think that it is out of focus. Btw, neither of us are members of NAR or Tripoly and therefore do not launch with clubs.Smile
BuiltFromTrash
First RMS Flight: June-17 2015
Pringles Can Rocket
G53-FJ-7 (29-40/120) 92 Newton-Seconds
~1300 Ft
Reply
#7
(10-28-2015, 08:36 PM)BuiltFromTrash Wrote: Naw.  It was taken with a phone camera and I think that it is out of focus.  Btw, neither of us are members of NAR or Tripoly and therefore do not launch with clubs.Smile

Well then, if that nozzle is not as bad as the  photo suggests you are good to go. 

The thing to watch for is eroded clay in the nozzle and forward plug. And Swelling, swelling is BAD!


Bill Clune L3 | NAR#88583
Been a launch Director
Founded a Club
MARS Club|SRC|MDRA - Forever
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#8
Thanks Bill, I had never seen that from before, while I will probably never come across motors that old, its good to know if someone asks that it can be done following the rules! I for one would like to see some of those old motors fly!
Dave Greger L3
NAR# 95846
MDRA #65

Hollie L1
NAR# 99687
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#9
(10-29-2015, 09:10 AM)dgreger Wrote: Thanks Bill, I had never seen that from before, while I will probably never come across motors that old, its good to know if someone asks that it can be done following the rules! I for one would like to see some of those old motors fly!

A few years ago at an MDRA launch someone flew a few large BP motors that were Sparky and long burning, very cool!
I would love to see a few of those on the market


Bill Clune L3 | NAR#88583
Been a launch Director
Founded a Club
MARS Club|SRC|MDRA - Forever
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#10
The F7-4 is one of the all time great motors. It is legendary. Songs have been written about it. It's known as The Steam Machine.

It is one of the most entertaining motors to fly. It's a black powder motor that burns for 9 seconds with the thrust curve of a C6-7 extended way to infinity and beyond.

It can barely lift its own weight in payload. Put it in anything bigger than a Big Bertha and it will struggle.

Even on the best of days, there's a fifty/fifty chance it will cato. This is not a problem. Just Think of the body tube & fins as expendable, like an igniter. Black powder motors, unlike composites, do not age well. If you fly these things, use a lightweight minimum diameter bird & kiss your rocket good-bye. You'll never see it againg. Stand people way back, have the cameras rolling, and enjoy. Success or fail, people will be talking about it for days.

The igniters are wonderful and rare. You'll never find their like again.

I love these things!
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