Hell Boy > 19 motor cluster

[billspad]

Thanks for the kind words all.



A fair concern.

First I plan to do a Saucer of DOOM (Applewhite 18") test flight with a ProX motor surrounded by 6x BP motors fired by QM to confirm the method.

That will be far more entertaining than a sim.

The last two flights of the Thunderbird had a ProX 24mm motor in the middle of 10x 24mm BP motors and they hit all engines at the same time fired by igniters.

If they were all ignited it the same time it wouldn't worry me. My only concern is how quick quickmatch is. Peak thrust on the F30 is around 11 pounds and I think you said Hell Boy weighs 8 pounds. When you figure in rail friction and drag it's not going to be moving very fast if the BP motors don't light. Actually the best case would be if it didn't move at all until they fired and you may be close enough to that.

 

[delta22]

Thanks to Bill Spadafora for this excellent liftoff picture.

 

[epickett]

Thanks to Bill Spadafora for this excellent liftoff picture.

Geez, Louise! That is SO cool...

 

[troj]

Thanks to Bill Spadafora for this excellent liftoff picture.

That poor blast deflector...I think 30 seconds in a blast furnace would be more gentle....

Awesome picture!

-Kevin

 

[bobkrech]

That poor blast deflector...I think 30 seconds in a blast furnace would be more gentle....

Awesome picture!

-Kevin

That "poor blast deflector" is actually a 1' diameter, 1/4" thick harrow disk. Cheap and virtually indestructible!

Bob

 

[KennB]

That poor blast deflector...I think 30 seconds in a blast furnace would be more gentle....

Awesome picture!

-Kevin

That "poor blast deflector" is actually a 1' diameter, 1/4" thick harrow disk. Cheap and virtually indestructible!

Bob

The yellow paint takes a beating at the first launch in April and it's pretty much carbon-coated the rest of the season. A little wire brush action and a fresh coat of paint over the winter and it looks good again - until April.

 

[delta22]

HellBoy flew a second time at the 11/21/10 CMASS launch.

This time prepped with 1x ProX F30 White and 18x D11-P motors.

Impulse: 1x 73 Ns + 18x 18 Ns = 397 Ns total

Thrust: 1x 30 N + 18x 11 N = 228 N

19 motors = I-228

Shortened the drogue harness to reduce risk of moderate tangling which occurred in the first flight.

Like the first flight, the BP motors were fired by a QM flashpan. Used one Rocketflite ML igniter for the AP motor and another for the flashpan. Flashpan was also exposed to AP motor exhaust to have two ignition sources. Used a small cotton string beneath 3 BP motors to prevent rocket creeping up the rail before the BP motors were pushing hard.

In the first flight the rocket took 0.5 seconds from first visible sign of ignition until it started moving up the rail. In this flight the time was reduced to 0.4 seconds, likely due to the addition of the fast hitting ProX motor. Times were determined by counting video frames in 720 60p video.

 

[troj]

I assume the white on the ends of the motors is tape? What is its purpose? To keep from cooking the motor casings when the pan lights?

-Kevin

 

[delta22]

The flight went very well, firing all 19 motors and reaching 863 ft.

Slight wiggle during boost suggests the need for slightly more nose weight with this engine combination. This flight was in very low winds.

Main chute was slow to unfurl, so I'll pack it to deploy more quickly next time. That's me trying to talk the chute into opening up in the video

Once again, the rocket is in great shape and will fly again next spring. Maybe with the addition of some cool flame graphics....

Video of HellBoy flights 1 and 2:

[video=youtube;m4MqCUMtF1E]https://www.youtube.com/watch?v=m4MqCUMtF1E[/video]

 

[delta22]

I assume the white on the ends of the motors is tape? What is its purpose? To keep from cooking the motor casings when the pan lights?

-Kevin

The tape on the BP motors is to form thrust rings, to keep the motors from sliding too far into the motor tubes.

By not putting thrust rings in the motor tubes themselves a wider range of motors can be used, like the F30 used in the center of this flight.

 

[troj]

The tape on the BP motors is to form thrust rings, to keep the motors from sliding too far into the motor tubes.

By not putting thrust rings in the motor tubes themselves a wider range of motors can be used, like the F30 used in the center of this flight.

Cool, makes sense!

I think you need to haul that beast to LDRS next year -- I'd love to see it fly!

-Kevin

 

[n3tjm]

Wow, nice flight . I am curious how you ignited the F30 with the D11's?

 

[billspad]

The burn string that you used to hold the rocket down sounded familiar to me so I took a look at the first edition of Stine's Handbook. I couldn't find the reference but I found this: "The largest number that has ever been ignited successfully is seven Type B.8-4 engines............Many flight tests showed that one could not count on simultaneous igntion of more than three engines per cluster with any degree of confidence." Stine was using Jetex wick. Not that your flight wasn't impressive but 50 years ago you would have been a rocket god.

For you youngsters, yes it's supposed to be .8. That's the average thrust in pounds.

 

[JAL3]

I'd very much like detail on the flash pan.

 

[stickershock23]

The flight went very well, firing all 19 motors and reaching 863 ft.

Once again, the rocket is in great shape and will fly again next spring. Maybe with the addition of some cool flame graphics....

Very cool Fatboy.. When you are ready for some custom graphics... I'll work up whatever you want.

are you using an igniter to light the central CTI? then the lit motor lites the flashpan in turn igniting the BP motors?

 

[UPscaler]

Very cool Fatboy.. When you are ready for some custom graphics... I'll work up whatever you want.

are you using an igniter to light the central CTI? then the lit motor lites the flashpan in turn igniting the BP motors?

I was about to bring up the fact that it looks awfully naked

 

[delta22]

HellBoy flew a second time at the 11/21/10 CMASS launch.

Like the first flight, the BP motors were fired by a QM flashpan. Used one Rocketflite ML igniter for the AP motor and another for the flashpan. Flashpan was also exposed to AP motor exhaust to have two ignition sources. Used a small cotton string beneath 3 BP motors to prevent rocket creeping up the rail before the BP motors were pushing hard.

Forgot to take pictures of the ignition setup for this second flight. In post 47, first picture shows ignition setup for first flight.

Second was similar except flashpan did not cover center AP motor, instead one strand of QM wrapped in paper jacket (like what sticks out to the side in the picture) sits across the front of the AP motor-but does not block or constrict the AP nozzle in any way.

So two Rocketflite ML igniters were used. One to fire the AP motor, the other to fire the flashpan. The flashpan was also exposed to the AP motor's flame for a second ignition source.

AP motors must be ignited by igniters and can not be ignited by flashpans due to heat and pressurization issues plus the fact that AP motors need to be ignited at the top, not at the nozzle end.

The igniter I put in the flashpan was to try to fire all motors as simultaneously as possible. The AP motor would have fired the flashpan, but probably 0.1 to 0.2 seconds later than the igniter.

As no one motor in this cluster was much more powerful than the rest, they all needed to fire within 0.1 to 0.2 seconds of each other for a quick clean acceleration off the rail.

This was achieved.

 

[delta22]

Very cool Fatboy.. When you are ready for some custom graphics... I'll work up whatever you want.

Yes, I want to get some cool Stickershock flames. Possibly a two color vinyl wrap for the 5.55" diameter body. More than 10" available length from top of body tube to top of fin chord and more than 15" available length between the three fins.

Was thinking about painting the nose cone orange and leaving the body yellow, with the flames as a transition between the two. Possibly the fat curling flame design seen on many hot rods.

Any suggestions appreciated, flames is a fun topic

As the rocket was built in a few weeks, hadn't yet had time for more than a couple hours of priming and paint.

 

[n3tjm]

That Pro24 looks roasted. Did the closure sustain any heat damage?

 

[delta22]

That Pro24 looks roasted. Did the closure sustain any heat damage?

With double layers of masking tape above and below the flashpan, the tape leaves sticky residue.

The ProX 24 case and closure cleaned up very nicely with baby wipes.

 

[stickershock23]

Yes, I want to get some cool Stickershock flames. Possibly a two color vinyl wrap for the 5.55" diameter body. More than 10" available length from top of body tube to top of fin chord and more than 15" available length between the three fins.

Was thinking about painting the nose cone orange and leaving the body yellow, with the flames as a transition between the two. Possibly the fat curling flame design seen on many hot rods.

Any suggestions appreciated, flames is a fun topic

As the rocket was built in a few weeks, hadn't yet had time for more than a couple hours of priming and paint.

Flames are really a fun topic. SOOOO many choices..

How about simple. yet 50's hot rod ish.

 

[UPscaler]

I think tribal orange flames with a black outline would look pretty awesome. Orange nosecone, orange flames, and just a bit of black pin striping.



BTW that's Mark's picture, from his site.

 

[delta22]

Been neglecting this thread...HellBoy has now flown five times, with the flash pan hitting every motor each time, 95 motors in 5 flights.

Last two flights were both powered by a core of 7x E9 motors in the middle and 12x D12s around the outside. Added 4 oz more nose weight before these flights to make up for the added weight of the central E9s, and the flights were nice and stable.

 

[delta22]

In honor of LDRS, finally gave HellBoy the look it deserves.

Thanks to StickerShock for the awesome flame vinyl decals.

Repainted the body yellow. Painted the NC red, and stuck on the flames!!

 

[delta22]

Then added 5.4 oz more nose weight and loaded HB up on 19x E9 motors.

First time all motors are E9s. Looking forward to the longer burn and a little more altitude.

Last pic shows the flash pan ready for launch.

 

[Aksrockets]

Someone give this man 19 E75s. Now THAT would me an awesome flight.

Alex

 

[delta22]

Someone give this man 19 E75s. Now THAT would me an awesome flight.

Alex

Flashpan + AP motors = trash bag recovery

Nothing but little bits to pick up off the field...

 

[UPscaler]

What about those new Estes E12s? That'd give it a ride!


Can't wait to see some footage of this!



Braden

 

[Aksrockets]

Flashpan + AP motors = trash bag recovery

Nothing but little bits to pick up off the field...

Well, CTI motors DO light in a hurry, flash pan would be out the option. The stock igniters might work.
Sorry about my day dream.

Alex

 

[blackbrandt]

19xE75 would be one hell of a flight.