70 Motor 2 Stage Project > "HellBoy 70"

Here's the video I took yesterday.

http://youtu.be/1bD4Be3m_DE

 

I just love the close-up where you can see the individual flames! It would have been cooler if both stages had fired, of course, but it was nifty that the electronics saved it from an unsafe (or unrecoverable) flight path. Good show!

 

View from the grass.

 

This is the video from my pad and spectator cameras:



Thanks for the other videos gentlemen.

 

Boris, your flights are inspiring. When I look at them, I want to add a ring of 24mm BPs around the central 38mm AP in the 4 incher I'm building.

I wonder if you can share more about your flash pan setup. In particular, I wonder about lighting the AP from an electric igniter and the BPs (or their flash pan) from the main motor's flame. This way if the main fails to start, I can avoid BPs ignition.

Ari.

 

Even though the 2nd stage did not fire... What a great flight! I mean, its awesome seeing that many motors fly! I really do like the fact that the raven did not let the 2nd stage fire because of the conditions. Really shows how well it works... (It did not fire because of that... right?)

 

Spent some time going over the data from the Raven.

Attached are screenshots of the data that I believe is most relevant. All three images show the same graph lines, but each has the mouse pointer (and data detail box ) at different key points:
> max acceleration > 8.84 Gs > less that I expected, resulting in lower
> max velocity > 143 ft/sec
> max altitude (barometric) > 406 ft

The four lines at the very top are the true/false firing criteria used for the second stage.

The only one that never went to true was velocity, the firing criteria was 144 ft/sec and the flight maxed out at 143 ft/sec!

Bill, you almost got to be an RC LCO and fire the safety charge.

The Raven has some very slick capabilities, but this flight weathercocking too much was not the reason it did not fire the second stage. The second stage did not fire because is was accelerating about 30% more slowly than both my sims and direct rough calculations had expected, resulting in 30% lower max first stage velocity.

 

Based on this info....the conclusion is obvious...MORE MOTORS!

For the next attempt in two weeks, an all C11 first stage to be able to stage quickly at 0.9 seconds and

51x motors in the first stage to provide 1.5x more first stage thrust and the same total impulse (as the first stage just fired)

so HellBoy 50 becomes the HellBoy 70

By accelerating a lot faster for half the time, will build into the flight plan a better positioning for the second stage event.

Other thing to change is to reduce fin area on the next booster to make rocket less overstable.

All other safety elements will be fully implemented again, including RC safety ejection charge.

So Bill, you get another shot at blowing up my rocket if it displeases you...er ..I mean flies off course...

But seriously, thank you Bill Spadafora for your help with this project.

 

Thank you. Inspired is the way I feel when I see the video of your amazing glider.

From a visual effect point of view, it will take a lot of BP motors to be visible next to a 38mm motor.

Pic 1: British Electric Thunderbird going up on a Cesaroni F30 White longburn + 10x 24mm BP motors
Pic 2: Soyuz on Cesaroni G125 + 16x 24mm BP motors (15x fired)
Both these flights all motors fired by high output cluster box and Rocketflite igniters. Fired the AP motors alone in other projects to to build confidence in their "instant-on" ignition.

Pic 3: Sirius Rocketry Saturn V on AMW J440 + 4x BP motors
Used a fast igniting big motor with some pyrogen added near igniter. Also rocket was too heavy (16 lbs) for the BP motors to fly, so they were for effect only.

Best approach is to use a very fast igniting AP motor, like many of the Cesaronis that have the pressed BP plug built in.

Quickmatch leading from the back (outside only) of the big AP motor into the nozzle of each BP motor should do the trick. A number of folks in England have done this successfully and posted some pictures.

Another possibility would be to use a timer to airstart the BP motors.

 

Was there ever any doubt that this conclusion would be reached? I see the natural progression of these projects culminating with Boris ordering pallets wholesale from Estes and going for another Carmack prize. I'm thoroughly enjoying following along: impressed, educated, and entertained all at once!

 

Yay! More motors, more margin of safety, more smoke, go Boris!

Ari.

 

I bought this on eBay a few years ago and never thought I'd have a use for it.

 

According to the Handbook of model rocketry, you can use a 12 gauge shotgun just as well...

:rofl:

 

Two things, Bill.
1) When did you every buy something on ebay with the idea that you would have a use for it - other than having cool stuff in your basement for the club meetings? and
B) You'll have to get that calibration brought up to date if you plan on using it at a sanctioned launch. :wink:

 

Thank you for your encouragement Boris. This is the essence of this place, isn't it? Taking inspiration and learning from each other.

The photos in your post show the BP motors quite visibly, even on the 4+J Saturn.

I like this idea. I wonder if you can point me to these people's posts. I'd like to see what they are doing.

The rocket I'm thinking of is very simple. It uses motor eject; no electronics onboard. The simplicity of a quickmatch appeals to me. It only lights the outboards if the main fires.

Ari.

 

You may have to be careful of chuffs, though.

Also, even CTI motors still have a slight delay between the initial burst from the igniter (which may or may not ignite the quickmatch) and the pressurization of the motor.

 

This is the layout for the 51x C11 engines for the booster.

Provides clearance for the launch rail, marked "RB".

Also the three large sustainer fins will be positioned above the three motors that protrude the furthest.

Plan to reduce booster fin area to make this flight less overstable. Six small rectangular fins will be used this time.

 

Repaired the small zipper with 5 small build ups of thin slow epoxy.

Attached inter-stage coupler used previously to 51x C11-0 engines with a generous amount of 5 minute epoxy.