F-100 'Bang Starts'
Exceprts from the F-100 Super Sabre Chat Room
The P&W J-57 had a large chamber to accept a large gas generating cartridge. When ignited by electrical current, the expanding gas from the black powder-like pyrotechnic cartridge drove a starter turbine which brought the engine up to a self-sustaining RPM via a drive system.
This eliminated the need for heavy and bulky ground starting units, but the starter cartridge spewed out a characteristic dense cloud of choking black smoke, which was often mistaken by inexperienced ground crews for an engine fire.
The powder charge for the ground start came in a big sealed can, and on opening and extracting the cartridge, you'd find two small metal tabs on the bottom of the cartridge. These tabs were the electrical contact that fired the cartridge when the pilot moved the throttle outboard on start, before bringing the throttle forward. As soon as a tiny RPM registered on the tach, you brought the throttle around the horn to feed fuel and engine ignition to the rapidly-building engine speed.
Sometimes the big metal receptacle that held the gas generator cartridge would get so dirty from repeated use that the metal tabs wouldn't make contact. Then the cartridge would refuse to fire, and the crew chief would give the starter receptacle a good healthy whack with a wooden wheel chock, usually curing the powder charge of any reluctance to detonate.
We'd often take a can containing a starter cartridge along with us as an alternative starting means on cross-country.
The story is told, of USAF Capt. John Green going into Memphis, Millington NAS or MCAS, in an F-100 way back in the early '70s.
He was met by a couple of young Marine ground crewmen, who asked what kind of plane he was flying. "F-100 Super Sabre" only got him further puzzled looks. One of the ground crew said, "Sir, I don't think we have tech data on this bird. What do you need for start, a huffer or just electrical"?
"Neither one," John replied with his tongue in his cheek.
“If I can get, oh, about six guys to give me a push to start me rolling, I'll just pop the clutch and get the engine started that way."
More and more doubtful looks. "Yessir" was their suspicious response. What else would a young Marine say?
The Hun was pretty finely balanced on the two main gear struts.
When you tapped the brakes, the nose strut compressed so much that the nose took a dip, just like the hood of our cars used to dip when being clutch-started after a similar push from our friends.
So now six Marines are standing at the ready, still doubtful but not about to question an Officer on Procedure. “Just get me going at about a fast walk," John instructed. “I’ll wave you all clear when we're fast enough, pop the clutch and be on my way.”
“Thanks for the good turnaround ! "
With six Marines pushing, they quickly get the bird up to a brisk-stepping speed. John waves his arms, and the Marines warily stand well clear.
The nose dips as John “pops the clutch". THERE IS A BIG CLOUD OF CHOKING SMOKE AS THE F-100'S ENGINE WHINES TO LIFE.
And off goes Captain Green to the takeoff end of the runway, leaving six puzzled Marines in his wake.
The thing that was interesting about that "story" is that we didn't carry shotgun canisters all the time.....in three years at Hahn/WAB I only used them that one time in Wildenrath. Usually the mechanism was so corroded from lack of use you were damn lucky to get one to fire!
Back at Tuy Hoa when I was with the 416th TFS (Oct 69 – Oct 70), we used carts all the time for our alert birds or other quick turn-around missions which were the rule rather than the exception. We kept the cart cans cleaned with JP4, a little elbow grease with a brush and we dried them well with a blast of high-pressure air. (This was VERY unauthorized, but effective!) We rarely had a failure to start and when we did, the chock-whack method worked great. (Actually, most of us used our handy-dandy 6” crescent wrench to give it a sharp tap on the handle.) I think that the only time we used the MA-4 GPU’s for starts were during preflight inspection run-ups, during maintenance or to start the few birds we had that didn’t have the cart-start capability. On the breezy beach at Tuy Hoa, the cart smoke cleared quickly, so that was not much of a factor.
I remember one incident where one of these birds without a cart-starter had a visiting officer (a bird colonel, I think) that was going on a mission for some reason. I was relegated to trash collecting duty that week on day shift when I noticed a large crowd around a revetment. (I was on a minor “punishment” in the sun for out-drinking our first-shirt at the NCO club, I think.) Regardless, the ground crew assigned for this mission were mostly senior NCO’s (TSgt’s and above) who were not recently hands-on. They couldn’t get air to the starter. I watched for a few minute and then I offered my assistance. (I taught engine systems at Sheppard AFB and had a good idea of what the problem was.) They reluctantly accepted my offer. Since I was young and stupid and the senior NCO’s had their private parts on the line, they let me up to talk to the pilot.
The colonel, who was obviously not recent with the F-100, did not press the start button that would normally fire the cart on cart-equipped birds. On non-cart birds, it opens the starter’s air inlet valve/45 PSIA regulator. The brief exchange went something like this:
Me: “Sir, please press the start button.”
Colonel: “This bird doesn’t have a cart installed Sergeant.”
Me: “Then what’s the button for?” I asked. “It’s there for something.”
The colonel and the acting crew-chief TSgt looked pissed-off at me but the colonel pressed the button anyway, the engine turned over and it started. The colonel and the NCO’s were happy and all was well with the world. And I went back to pick up the trash.
I didn’t have to buy my drinks that night. And … they put me back on my regular assignment on night shift doing preflights, servicing and maintenance where I was happy, out of the sun and away from the normal daytime bulls--t.
While at Phan Rang 70-71 I worked the Alert pad most of the time. (Weapons loading). Most of the time when they scrambled 2 birds we were still in the building and went out to prep the bombs soon afterwards so I wasn't there when most of them started but when I was there I think they only used the cart start. I know the "Deuce" was there incase it was needed but I don't recall seeing one being used. I guess the "Chock knock" worked if it was needed. The smoke around the revetments would take a minute or so to clear but down at the alert pad they faced the wind most of the time and the smoke would go out the back rather quickly.
When I was at Luke, we had a pilot going X-country, and thought it would be a good idea to have a couple of carts with him, just in case. He had never done a cart start, so we set one up for him to try before he left. I think half of the flight line had never seen one, as we were surrounded by troops with fire bottles shortly after he hit the button.
It is very interesting the responses on this topic...something you wouldn't bring up over a beer and yet the differences are enlightening. As I mentioned before...Three years at Hahn and Wheelus we never used the shotgun start except the one time I used it at Wildenrath (I think they sent me up there because nobody else had ever seen one much less know how to use it )and yet a few years later it seems like it was the primary way to start the sled. Tech orders DO change!!
Cart starts I remember were on alert pad too. Quicker I guess and you got nothing to unhook before takeoff.
Cart starts were common at Tuy Hoa when I was there,' 67-' 68, and not only on the alert pads.
It seems to me that we used them quite often when we were in the Tac Eval mode and doing max loadouts or doing fast turn-arounds for simulated close air in Germany. Anyway, they were used often enough to very familiar.
.....ahhhhh, the old "shot gun" start ! #10 can full of gun powder. I was flown up to Wildenrath, RAF in a L-20 (U 6A Beaver) to shot gun start a D and an F model......the jocks landed there for a beer without realizing that the British had Canberras with Rolls Royce engines......guess they thought they could push start it !!!