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Hot Rod Nitro FireBall
Amazing Onboard Video - 18 engines fired, 2 stages, 7 rockets, one flight! (flight 2: LDRS - 8MB)

Flown on 9 to 18 engines and launched 6 second stage rockets in flight
Team project by Boris Katan and David Mackiernan of HotRod Rocketry
7 feet tall by 4 inches diameter.   Flight weight 14 pounds.   
Click on any picture to enlarge

     Hot Rod Nitro FireBall     flight 3     9/19/09     CMASS     Amesbury, MA

The flight was a fun one, on a clear and windy day.
My son Paul showing the business end of stage 1.
David, Alan and I up to no good at the pad.

The liftoff sequence of 5 pictures as quick as the Canon XS will go, 3 frames per second.
The H255 fires quickly, only half the D11s are ignited.
Ignition of the 6x second stage Nitros is exciting and mostly successful. 5 are fired and 4 fly upwards
Recovery of central rocket is good, using deployment bag and 7' chute.

The Nitros quickly filled the sky, shooting off in all directions. One even headed straight down and pranged under power. That's why everyone was 200+ feet back.    It may have been bumped, turbulence and wind were big factors too. This Nitro was the only thing damaged in the flight.

Main rocket only went up 448ft, due to a few engines not fired, weather cocking, and planned moderate impulse. Thrust at the pad was reduced 18% due to stage 1 motors not fired, 5 of 6 showed signs that the ematches fired, but not the BP motors. Made sure in advance that BP was visible at the bottom of each motor nozzle.

The Nitro's ematches were held in place with Estes igniter plugs, usually I use tape. The plugs worked well for 5 of the Nitros, but one ematch was damaged by jamming in the plug, and that's the Nitro that stayed with the main rocket all the way back to the ground.

Unfortunately, the onboard video camera shut off before the flight took off.

     Pre-Flight Planning:    
Prepped similarly to the way it was at LDRS for flight 2, except:

1) Less thrust on the main rocket. About 2/3 of LDRS flight, resulting in reduced acceleration and wind speed that the Nitros have to deal with 0.6 seconds into flight when they are ignited.

Stage one has 1x CTI/AMW 29mm 6 grain H255 Blue and 12x Estes D11-P motors. (dual ematches in the H for insurance)

The 6x stage 2 Hot Rod Nitros has the same D12-5 motors as previously.

2) Stage 2 Nitros are slightly more snugly mounted to the stage 1 main rocket.

     Hot Rod Nitro FireBall     flight 2     7/3/09     LDRS 28     Potter, NY

 great sequence of liftoff pictures by Neil McGilvray and Todd Haring

The Hot Rod Nitro Fireball project flew well at LDRS. Fired 18 of 19 installed motors, using 5 different motors from 4 manufacturers:

All motors fired by Rocketflite MF ematches boosted with Rocketflite ML pyrogen, both ejection charges were also fired by MF ematches.

Stage 1: 1x AMW Pro-X 29mm H170 Blue Streak 2x AT G71 Redlines 4x Roadrunner G80-10 (smoky motors, one of these did not ignite, usually these fire quickly) 6x Estes D11-P (at the fin tips) The H was in the center providing the long flame tail, surrounded by the 6x G motors pumping red and black into the flame. The BP motors in the fin tips fed their flame into the AP fireball below the rocket to good effect.

Stage 2: Were the 6x Hot Rod Rockets Nitro rockets each powered by a D12-5.
Fired by a Perfectflite MT3G timer at 0.6 seconds. These all fired and went in an upward direction to cool effect.

However, they appear to have been buffeted hard by turbulence from the main rocket, and were not pointed straight up immediately after separation. We will have to "fine tune" this part for the next attempt.

Fired stage one impulse was J powered at about 840Ns. Stage two added about another 100Ns. The complete rocket weighed 14.0 lbs at RSO inspection.

The main rocket (AKA Ultimate FireBall) reached an altitude of 1272ft and deployed 3ft drogue at apogee. Second ejection charge fired at 400ft, but the main jammed, fortunately the very soft muddy ground prevented any damage due to the quick landing.

     Pre-Flight Planning:    
Updated the long flight setup checklist based on lessons learned from the first flight and replaced timer switch.

     Videos:

Amazing Onboard Video - 18 engines fired, 2 stages, 7 rockets, one flight! (flight 2: LDRS - 8MB)  

same onboard video, cleaner image, but no slow motion replay (15MB QuickTime)

Movie made from sequence of liftoff still images (2MB)

First part of the 8MB video is the launch at normal speed, second part is first few seconds slowed 16X.

In the slo-mo can see:
- the very energetic (and sparky) firing of the Rocketflite MF ematches boosted with ML pyrogen firing 18 of the 19 installed engines
- the flash of blue as the AMW/CTI H170 Blue comes up to pressure first
- 11 other motors coming to life in a flash
- the 6x Hot Rod Nitro rockets firing and separating from the main rocket, several of them tumbling and spinning end over end as they started their separate flights!

     Hot Rod Nitro FireBall     flight 1     4/29/09     CMASS     Amesbury, MA

     Pre-Flight Planning:    
Motors ignited at the pad: 3x G77R, 4x F40W, 6x D11-P. Using the same Rocketflite MF ematches wired in series and parallel configuration described in detail on the Rocketflite page of this website. Initial flight weight 13 lbs.

At 0.6 seconds a Perfectflite MT3G timer will fire the 6x Nitro second stages.
The Nitros have initial separation liftoff weight of 4.8 oz and are fired by 1x D12-5 each.

Thrust curves and rocket weights appear to confirm that the second stage rockets will pull quickly away from the first stage carrier rocket. Did not attempt to use RockSim due to project complexity.

Using the online sim at webalt.markworld.com :

Separation at 0.6 seconds occurs at
> altitude: 50ft
> acceleration: 120 lbs thrust / 10Gs
> speed: 140 mph

at 0.8 seconds
> the main rocket continues to accelerate at a gradually reducing rate
> the 6x Nitros have peak acceleration of 18+ Gs quickly pulling away from the main rocket

Nitros use apogee streamer recovery. Ultimate FireBall uses proven setup of apogee drogue and main at 400 ft.

 
before and after flight

Lift off was slow on a column of fire, reaching only 484 ft.
Main rocket completed a clean recovery using deployment bag.

While the flight was safe, three elements of the flight failed.
> Two of the G77Rs failed to light. This had a lot to do with the low altitude. As they were both on the same series string of ematches, suspect that part of the circuit lost continuity during the complex setup at the pad.
> Two of the outboard D11-Ps failed to light. For the first time, tried using wadding under tape to hold the ematches in place, but this approach did not work well.
> The timer switch failed, so the 6x Nitros did not fire. The Nitros stayed with the main rocket until apogee drogue deployment, then they separated and fell to the ground.

     Videos:     Onboard video (9MB QuickTime)     Pad Cam Video by Bill Spadafora (youtube)

     Hot Rod Nitro FireBall     the build

We took the 7ft tall x 4in diameter Ultimate FireBall, built a "Ring of Fire" and screwed to the fins.
                                                                                                         David and rocket.

Ring of Fire: 1.6" cardboard tubing first stage pods with 1/8" plywood tabs that screw onto fins.
Joined and reinforced the tail assembly with 3" x 1/8" basswood strips just over 4" long.
Reinforced with 3oz fiberglass and painted with epoxy internally.
Then mounted 6x Nitro rockets to it.