Motor Quesion...

[JSP]

I have a question and don't feel like doing the research . :rolleyes:
What are the closest modern engines to the FSI F7 and F100? I know there aren't any black powder F's out there any more (that I know of) but what would be the closest composites?

[ghrocketman]

Apogee has a composite long-burn low-thrust F10? that is close to the FSI F7, but is a full 80ns F instead of only ~60ns of the FSI engine.
As far as the F100, the FSI engine was ACTUALLY around an F80 with 55ns total impulse.
Any composite around those specs would fit the bill.

[rraeford]

I've found the E6 medalist motor to be more like the F7 (when the F7 actually worked). There's no real equivalent though because every F7 flight was both a gamble and a thrill. You're just not going to get that kind of excitement these days unless you pack your own.

As far as the F100, the best thing about this motor was it's high power/short burst personality. Though not as powerful as a composite F (or E for that matter), it was fun and loud! The nearest equivalent I've found to the experience of the F100 is the Aerotech G125. This motor is MUCH more powerful. It has a half second (give or take) thrust duration and even a good sized mid-power rocket – like an Aerotch Initiator–will disappear off the pad with a LOUD bang. Fun stuff!

Apogee also sells a D10 which has a TD of 1.9 seconds. Might be fun to see how that one flies.


Romie

[Nuke Rocketeer]

I've found the E6 medalist motor to be more like the F7 (when the F7 actually worked). There's no real equivalent though because every F7 flight was both a gamble and a thrill. You're just not going to get that kind of excitement these days unless you pack your own.

As far as the F100, the best thing about this motor was it's high power/short burst personality. Though not as powerful as a composite F (or E for that matter), it was fun and loud! The nearest equivalent I've found to the experience of the F100 is the Aerotech G125. This motor is MUCH more powerful. It has a half second (give or take) thrust duration and even a good sized mid-power rocket – like an Aerotch Initiator–will disappear off the pad with a LOUD bang. Fun stuff!

Apogee also sells a D10 which has a TD of 1.9 seconds. Might be fun to see how that one flies.


Romie

In over 100 launches I never had either a F7 or a F100 fail. Maybe I was lucky or the Cato gods just decided that for me the E60 would be the designated destroyer of rockets. In my experience with FSI engines, I had 50%+ cato rate with E60's, about 20% with D20's and D18's and zero with E5's, F7's and F100's.

Those were fun to fly and I sure wsh that there was some way to bring them back. My hobby store going-out-of-business stash from 1986 is down ot the last ones.

Joe W

[tbzep]

To simulate an F100, try a cluster of about 20-25 A10-3T motors. :D

You'd have to calculate the actual specific impulse of the motors to get the right number of motors to cluster. The FSI motor was heavy, so it's no big deal to cluster up a bunch of the little motors. The A10-3T motor produces the bulk of its thrust in a fraction of a second like the F100. It does have a bit of residual thrust after the big spike, but not really enough to care about and the rocket will be long gone from the initial spike. To add to the realism, you get to smell burned sulfur after the launch...something the composite motors just can't replicate. :D

[ghrocketman]

I never had a CATO with the FSI F7 motor....several were "under" thrusters (maybe 10%) that caused my rocket to barely lift off the pad and flop around on the ground, but never a CATO.
I did however have SEVERAL CATOS with the F100, E60, D20, and D18.
In my experience, the E60 had the highest CATO rate of OVER 50%, the F100 was second with a CATO rate of somewhere around 30%. The D20 and D18 were somewhere between 15 and 20%, which is still much higher than anything I'd be inclined to use with ANY regularity in any rocket I value.
I still have several F7, F100, E60, D18, and D20 motors that will NEVER get used.
The only FSI motors that I had a relatively good success rate with were the E5 and F7.
I'm not sure that the E5 actually had any more impulse than an Estes D12....the flights usually were actually lower. I know my RMS24 D9 and D15 reloads fly similar rockets higher than either the E5 and D12.
The FSI large hi-thrust BP engines were very similar to flying the old Centuri Mini-Max offerings....you never knew if you were getting a rocket flight or an M80 kaboom until you hit the launch button.

[tbzep]

Yep...FSI motors were a crapshoot. That's why I really loved the Rocketflite black powder motors. I had a 100% success rate with their "F" motors, and the Silver Streak versions were huge crowd pleasers. I wish they were back in production.

I only have experience flying the "F" motors. I've seen several of the "H" motors cato, but I believe they were older motors well after production had stopped. I never saw any "G" motors cato.

[Nuke Rocketeer]

I never got to fly Mini-max motors. I got into the FSI motors in my first BARhood right after college in 1980. I know as a kid, I often dreamed of getting both Mini-Max's and Enerjets, but the cost of the motor and shipping was WAY over my rather slim rocket budget at that time.

Joe W

[rraeford]

I had a personal record of nearly 100 flights with F100s without a CATO. I did have a couple with overly enthusiastic ejection charges but even those flights ended OK – even if the rockets were a bit charred.

As far as the F7 was concerned. I had few CATOs. Really inconsistant performace was my beef with that motor. The same went for the E5. From batch to batch they would change. I had a few dedicated models for those motors because of the odd MMT sizes. All of the models were lightweight and on the overly stable side. Every once in while (using E5s and F7s) these models would climb maybe 50 feet and fall backwards to the ground and flop around until the “thrusting” stopped. The flight before and the one after might be spectacular but ... you just never knew.

Yeah, I'm to the end of my stash as well.

Romie

[JSP]

I think the problem with the F7's was that the paper casing was just maginal as far as containing the pressure from the long burn. Still, my most exciting cato was from an E6. It blew the bottom half of my FSI Nova to bits. This is a picture of that rocket on an earlier flight (around 1989) I still have one E6 and a D20-0. They're safely packed away in my "collector motor" box...

[ghrocketman]

That's a cool pic !
I didn't remember the E5 having a flame that large.

[Nuke Rocketeer]

I wish I had a photo of a 3 stage F100/F7/E5 rocket I built back in 1988. I launched it and got it back 3 times and lost it to a high wind upstairs on the 4th launch.

Joe W

[JSP]

Thanks! Who knows, maybe that was a "hot" motor. I know the next one was...TOO hot! :eek:

[Green Dragon]

In over 100 launches I never had either a F7 or a F100 fail. Maybe I was lucky or the Cato gods just decided that for me the E60 would be the designated destroyer of rockets. In my experience with FSI engines, I had 50%+ cato rate with E60's, about 20% with D20's and D18's and zero with E5's, F7's and F100's.

Those were fun to fly and I sure wsh that there was some way to bring them back. My hobby store going-out-of-business stash from 1986 is down ot the last ones.

Joe W

Just the opposite here... I;ve never had a D20,D18 or E60 cato.

a few F100's over the years ( still hoarding a pair for someday ).

had lots of E5 and F7 catos.... cost me some cool birds, too like my Collossus, vintage Ace Legal Allegro (at LDRS 5), and my brothers styrofoam cup rocket ( circa 1985-5, these from the 3-2-1 contact tv show filmed at WUBBA 7 or 8, iirc) .

~ AL