Perfect use for old FSI F7-4 motors?

Does your field require insurance? These motors are no longer certified. That makes them illegal to fly in most states, and voids your insurance coverage. Probably not wise for a scout demo launch.

I've tried flying such things on F7s back when they were still legal. The sustainer thrust is so low, they have a tendency to fall out of the sky while still under thrust. Not good at all.

There is no need to impress small children with a large or loud rocket. They will be thrilled with any small or medium model rocket that launches and recovers safely.

Many adults make the mistake of thinking they need to "impress" kids or put on a show. This often leads to unsafe attempts at "spectacular" and even injury to the children.

Now to the immediate question: An F7 is uncertified, so if you live in a state that requires certified motors or require insurance this is a No No. Next, a flying saucer is extremely prone to weathercocking and with a pitifully low thrust motor like the FSI F7, it will arc over and hit the ground (or a child's face) while still thrusting. Then several seconds later the ejection charge will go off. if it landed on grass, that starts a fire. if it hit a child in the face, then the rest of the kids who walk over to see what happened or the adult who runs over to help the injured child will then get hit by the flaming ejection charge.

Saucers need the correct thrust motor to fly safely and they prefer plugged motors or a very short delay to eject at a safe altitude.

-Fred Shecter

A member of our club tried to fly an Applewhite saucer on an old Aerotech F14 the other day. After the thurst spike, the rocket fell to the ground, still thrusting. I would think an F7 which is half the thrust and half the total impulse, and which can barely lift itself, would have a much worse time with a high drag saucer.

I say don't waste the motor on that. Find a small, minimum diameter rocket for it and let it do its thing.

Roy nar12605

My thanks to the group for the advice....I guess I'll have to rethink the saucer idea, guess I got caught up in the coolness of the idea. I'll stick with the tried and true...Chrome Dome, Blue Ninja, etc. I still might build a saucer, but I'll stick with the one that flies on a plugged A10 mini motor. (My original idea before I was struck with the thought of trying for altitude at the same time.)

I'm still intrigued by the idea of flying a saucer with an F7, but I'll leave that for my own personal testing and fun and fly it at my normal (and isolated) launch area. Thanks much for the advice. (Special note to Mr. Kaplow...I followed your advice from one of my previous postings and am building my Onyx with yellow glue...haven't flow it yet but I'll let the group know how it turns out. The rocket is now in the final finishing stages and should be ready to fly within a week. Should look kind of neat...it's painted dark orange with a reflective gold nose cone and fins to assist in tracking the rocket during descent.) Craig

Cluster those F7's!

Ted Novak TRA#5512 IEAS#75

Roy Green wrote:

I remember back at a elementry school open house we did a model rocket demo in the school yard. We did all sorts of A, B. C and D motors and for our grand finally we flew FSI F7 in an estes Goblem, which normally works great, but not this time. In front of 100s of parents and childern it took off and at about 100 ft. it started arcing over and under full thrust plowed into the roof of a house about 1/4 mile away, they all loved it and cheered and clapped with yellings of oncore.

Dave

Didn't you sometimes get two or three lift-offs on one F7?

I'm with Dave...

Wrapping up a LOC Viper IV project (pretty healthy stability margin) with some additional side pods mounts to burn up accumulated odds & ends... Will later finish the debate how to be done with all the 10.5 mm bp motors I've got.

Dave - Great pics! The shot of getting stuck at Lucerne reminded me of burying the rental car up to it's axle at Hemet. Even after trips to the car wash, the car never quite drove the same again!!! Andy Woerner pulled us out of the mess that afternoon. Great guy!

Andy

One of the best demo rockets is the Estes "Fat Boy". It has a little size to it and can be flown on a range of motors; from a short delay B motor, for a small school yard, to a monstrous C motor depending on the school yard size.

Fred

snipped-for-privacy@netzero.net wrote:

bob:

I find it both sad and funny all at the same time that you are reading the riot act to this guy about firing off illegal F7-4's. While I agree this is probably not the ideal place and time to fire off OOP decertfied model rocket motors, can you explain to us, if firing off decertfied OOP model rocket motors is probably illegal for this specific person, how can the NAR sanction such activities by its own membership?

It's time to fly some old motors (but see below) NAR Safety Committee Request for Proposals: Expired Motor Flight Testing

Background

The NAR Board of Trustees in its July 2006 meeting authorized a Safety Code Commensurate Compliance Program whereby the Board or its designees may review and approve proposals for commensurate methods of compliance with the Safety Code(s) of the Association for activities that may otherwise be perceived to technically violate some portion(s) of the Safety Code, provided:

. The activities are conducted in accordance with applicable laws......

Notice how the NAR uses the "term" Expired versus using the correct term:Decertfied? Is this another example of NAR "doublespeak'? I've never seen anybody use the term "expired" to denote decertified. And I don't think the NFPA codes use that term either.

Notice "perceived technical violations" ... perceived by whom?

Also Notice they say you can only do these activities IF they are conducted in accordance with applicable laws?

I would submit that theres no way ANY person can legally fire OOP decertfied/expired model rocket motors in any state or locality in which the NFPA fire codes are in place.

I guess the NAR doesn't consider fire code violations, violating any "applicable laws".

I might add that I am all for NAR members or for that matter anybody, to use OOP decertfied/expired model rocket motors unless they were decertfied for safety reasons.

terry dean

nar 16158

Good thing I fly under the SIAR flag, we don't mind seeing those engines flown at all.

Is it time to break out the old USR motors? I still have a 29mm Buttkicker reload around somewhere. Also, it has some nice voids in it to increase the kickin.

Phil

So the SIAR doesn't have any problems with violating the law? What does your flight insurance company think about that?

Speaking of USR...... Naaa, let's not go there.....(:-)

Fred

I used to call those "power voids"

Anyone know where to get thrust curves for their motors? Sent Jerry an email but he didn't respond. Not surprisingly, they do not show up on the NAR or TRA web sites.

Phil

Good luck!

Some curves do exist from early TMT thrust stand tests and were published in the Tripolitan.

Which motors are You interested in?