NateB
Well-Known Member
Not approved by the rocket groups, but black match or thermalite works for the old ways.
Gonna’ ignite like the rocketeers of old
- Thread starter brockrwood
- Start date
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Or cannon fuse.
Just take those old records off the shelf!
Cineroc! ;-)
Where has the photomat gone?
Where have the theodolites gone?
Where have the 1/4 rods gone?
Anyone got some dope?
Die cut fins?
Where have the theodolites gone?
Where have the 1/4 rods gone?
Anyone got some dope?
Die cut fins?
1/4” rods come from Denver Hardware, Colfax and Monaco.
OK. I have created a loop in a piece of 32 gauge nichrome wire. The wire is 3 5/8 inches long - about the same as an Estes igniter. The ohmmeter days it is 3.3 ohms of resistance. Hmm. That is a bit more resistance than I was expecting.
Ah. If I shorten the leads by about 50 percent I get 1.7 ohms. That’s better. Hmm. I guess if I am using pure nichrome wire as an igniter, I need the leads to be as short as I can make them.
Hmm. It is hard to tell if the little coil of nichrome wire is actually touching the propellant or not.
What size spitball of wadding should I use? The throat of the nozzle looks pretty narrow at the bottom.
(Golly, how did the old-time rocketeers ever get an igniter to work?)
(Golly, how did the old-time rocketeers ever get an igniter to work?)
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Well, resistance is going to be proportional to length (for that wire, about an ohm per inch it would seem).
In general, the wire will heat up evenly along its length. So ideally, you only want the nichome itself to be the part that heats up and ignites the propellant. Any additional length of wire is just generating waste heat.
So yeah, shorter is better.
Like this?
1.4 ohms at this length. About as short as I can make the leads and still be able to get clips on them.
Sorry, my previous comment was a bit dunderheaded... it's not the length of the wire that matters, it's the length of the wire between the clips. So you can make the wire as long as you like (for convenience) and just apply the clips as close to the motor nozzle as possible. The extra wire pigtails don't have any effect on anything.
Good point.
The commercially made Estes igniters are just two ordinary wire leads (very low resistance) with a short (about 1/8 inch) piece of nichrome wire connected between the two leads. How they get the nichrome wire to stay connected between the lead wires, I have no idea.
Solder, presumably. Then embedded in cornstarch (or whatever they use on the new ones) to strengthen and stabilize.
OK. Here is the same homemade nichrome wire igniter with the clips on the leads as close to the nozzle as I can get them. The measured resistance is 0.7 ohm. That is about the same as an Estes igniter.
The clips will get blasted by the engine exhaust.
If you're firing with a 12V system (or a LiPo, or something similarly powerful) then I would guess a little extra length won't hurt, if you want to at least move the clips out of the way of the exhaust blast. Something in the 1-1.5 ohm range would seem to be fine, based on a quick bit of mental math. That should still enable several amps to flow.
Raw nichrome ignition veterans can comment further.
Raw nichrome ignition veterans can comment further.
What I could do is wrap some regular 24 gauge solid wire onto the nichrome wire leads right where the leads come out of the nozzle. Then I could attach the clips onto the regular wire leads well out of the way of the engine exhaust.
Of course, at that point, I am NOT launching like the rocketeers of old and I might as well just use the Estes igniters that came with the engines.
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It's spot welded. The machine that has rolls of two different types of wire and two rolls of sticky paper tape as an input and completed igniters (including the pyrogen or other protective dip) as its output is about the size of a big office desk. There are two of them in Penrose. Those of us who got to go on the NARAM-60 tour got to see one of them in action. Quite fascinating to watch.
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Make the ball whatever size is a firm fit in the nozzle you have (press it in with a piece of small dowel or a blunt pencil) just like the plastic plugs and a regular igniter.
I still use the "spitball" technique when holding Q2G2s in motors for clusters. Much more secure than the little plastic straw that comes with them.
I'll let YOU suggest that to Mallory Langford or Bill Stine or Dave DelVecchio.The “Mabel” for igniters.
Of course, they may have names (good or bad) and we just don't know them.....
@neil_w I have tested the homemade nichrome igniter with a 12 volt Sealed Lead Acid battery. The battery was charged to 13.2 volts.
When I used the 32 gauge nichrome wire, the wire glowed white hot for about a 10th of a second and then broke.
When I used the 28 gauge nichrome wire, the wire glowed white hot for about 1/2 second (or maybe 1/3 of a second) and then broke.
As you can see from the picture, I attached the clips fairly far down the nichrome wire. As @neil_w said, it did not matter much. With 12 volts, the igniter burned in half in short order.
This begs the question: Will these nichrome igniters break so fast that there is no time to ignite the black powder in the rocket engine?
Only one way to find out…
When I used the 32 gauge nichrome wire, the wire glowed white hot for about a 10th of a second and then broke.
When I used the 28 gauge nichrome wire, the wire glowed white hot for about 1/2 second (or maybe 1/3 of a second) and then broke.
As you can see from the picture, I attached the clips fairly far down the nichrome wire. As @neil_w said, it did not matter much. With 12 volts, the igniter burned in half in short order.
This begs the question: Will these nichrome igniters break so fast that there is no time to ignite the black powder in the rocket engine?
Only one way to find out…
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Ladykate
Well-Known Member
We make them in the pyro world. 22 gauge solid copper wire with the insulation off 1/4 inch or 6mm or less. mate two wire stubs parallel and wrap the nichrome around each one (separately). You can solder nichrome but it doesn't like it much - but you need to. Dip them in a pyrogen - search for pyrogen on YouTube.
Here is a guy who makes them with safety matches from a small book of matches. He uses fine copper wire instead of nichrome.
Here is a guy who makes them with safety matches from a small book of matches. He uses fine copper wire instead of nichrome.
So, use regular 22 gauge wire for the leads but wrap some coils of nichrome around the ends of the leads you insert into the nozzle?
Trying two different tip coatings. One is Testor’s enamel “Steel”. One is nail polish: “silver storm”.
Getting the paint to stick to the tip of the igniter is harder than I thought it would be.
Getting the paint to stick to the tip of the igniter is harder than I thought it would be.
shockie
High Plains Rocketeer
Before electrical ignition of model rocket motors was independently developed by both G.Harry Stine and Orville Carlise, they stuck a fuse up the nozzle and lit it with a punk.
Well, do you feel lucky punk?
In Germany you can still ignite your. model rockets with fuse. KLIMA sells the fuse.
NFPA1122 prohibits that but what happens in Vegas stays in Vegas.
Wink.wink.nod.
Well, do you feel lucky punk?
In Germany you can still ignite your. model rockets with fuse. KLIMA sells the fuse.
NFPA1122 prohibits that but what happens in Vegas stays in Vegas.
Wink.wink.nod.
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