Whistle mix

[PhPyro69]

Good day pyros, i have a problem regarding my whistle mix. When im using hot whistle composition i got no whistle and weak thrust but when im using toned down composition it whistles nicely. Hot whistle using 76:23:1:4 kclo4:Na.Benz:Red Iron Oxide:mineral oil. 70:30:1:4 this is the composition that whistles. What seems to be the problem of this. Im from philippines where raw materials are expensive and hard to find. My tooling is diy using 12mm Id 6mm core and 1.5inches core length. 20t hydraulic press was used but no pressure guage, i only rely on my senses. 
 

also, when using 70:30:1:4 the core seems to strobe or like flickering producing less thrust.

[Zumber]

Whistle is coreless right?

I have not heard about core burning whistle.

[PhPyro69]

13 minutes ago, Zumber said:

Whistle is coreless right?

I have not heard about core burning whistle.

What do you mean coreless? It has a core shorter than that of a bp rocket motor if im not mistaken. My problem is when using hot mix i wont whistle and when i got it to whistle it is strobing or flickering generating less thrust. Both fuel and oxidizer are ball milled separately to almost airfloat and no gritty feel.  

[Zumber]

58 minutes ago, PhPyro69 said:

What do you mean coreless?

Composition pressed having no any gap in center or no any core in center.

End burning.

Please post image of motor.

[DavidF]

Whistles have no core. Whistle rocket motors usually are cored, except for bottle rockets and whistling girandola drivers with very hot whistle. Most folks use Vaseline (petroleum jelly) instead of mineral oil. Some folks  use wax. For solvents, folks use lacquer thinner or naphtha. 4% seems high for the oil. Most folks use 3%. I use 2 1/2% wax. Benzoate whistle on a spindle like that won't give a lot of thrust with iron oxide. The 76/23/1 formula can give a lot of thrust with copper oxychloride. The 70/30/1 formula is what's usually used with benzoate whistle. It's described as 'raspy'. Tiny chunks of whistle blow off as the core burns, which is what gives that sound. The raspiness goes away when the whistle above the spindle burns, after the core burns out. Usually a lack of whistle sound is due to the benzoate not being fine enough. 

Wichitabuggywhip website that Kevin recently copied for us has a lot of whistle info and tests that might be helpful.

 

[PhPyro69]

2 hours ago, DavidF said:

Whistles have no core. Whistle rocket motors usually are cored, except for bottle rockets and whistling girandola drivers with very hot whistle. Most folks use Vaseline (petroleum jelly) instead of mineral oil. Some folks  use wax. For solvents, folks use lacquer thinner or naphtha. 4% seems high for the oil. Most folks use 3%. I use 2 1/2% wax. Benzoate whistle on a spindle like that won't give a lot of thrust with iron oxide. The 76/23/1 formula can give a lot of thrust with copper oxychloride. The 70/30/1 formula is what's usually used with benzoate whistle. It's described as 'raspy'. Tiny chunks of whistle blow off as the core burns, which is what gives that sound. The raspiness goes away when the whistle above the spindle burns, after the core burns out. Usually a lack of whistle sound is due to the benzoate not being fine enough. 

Wichitabuggywhip website that Kevin recently copied for us has a lot of whistle info and tests that might be helpful.

 

So the correct term for the strobing like effect is raspy? Sometimes when i got the pressure in the fuel grain right i got a wooshing sound rather than a so called “raspy sound” and much better lift. As for the composition, it seems that the 76:23:1 is for short cored whistle motor using copperoxychloride and thats why my rocket wont whistle at all and only whistle when im using 70:30:1. Can i increase the core/spindle to compensate for the weak thrust? Ive seen here in the forum that says 3x of the ID is the max of the core so i went 1.5inches for the core. My 1/2” id can only lift a total of 60grams at a decent height. Much higher if it is not a raspy launch.

[DavidF]

That's the term people use, yes. I think it's also due to imperfections in the grain, just one guy's opinion. Also, it would be good to know your loading pressure. If it's way too high, you will likely see or feel ripples on the outside of the tube corresponding to the increments. I assume a tube support is used (and shield?).

The 76/23/1 is generally a salicylate-based whistle, using iron oxide. It's used on a short spindle. 'Regular' 70/30/1 benz whistle is very weak on a short spindle. The 76/23/1 benz whistle that has a lot of power uses copper oxychloride. You can increase the spindle length, but maybe try a little less pressure first? 

Here's a thing that can reduce your thrust too: Sometimes the propellant grain at the bottom has cracks in it from too much pressure and maybe too dry air. It just happens sometimes. If your bottom of the grain has cracks, it will break away without giving any thrust. If this condition was bad, it might make a strong 'strobing' effect like you witnessed. If you mount a motor upside down on a stick and video it, you can see how many chunks are blowing off during the thrust phase. That's what I did anyway. 

[PhPyro69]

23 minutes ago, DavidF said:

That's the term people use, yes. I think it's also due to imperfections in the grain, just one guy's opinion. Also, it would be good to know your loading pressure. If it's way too high, you will likely see or feel ripples on the outside of the tube corresponding to the increments. I assume a tube support is used (and shield?).

The 76/23/1 is generally a salicylate-based whistle, using iron oxide. It's used on a short spindle. 'Regular' 70/30/1 benz whistle is very weak on a short spindle. The 76/23/1 benz whistle that has a lot of power uses copper oxychloride. You can increase the spindle length, but maybe try a little less pressure first? 

Here's a thing that can reduce your thrust too: Sometimes the propellant grain at the bottom has cracks in it from too much pressure and maybe too dry air. It just happens sometimes. If your bottom of the grain has cracks, it will break away without giving any thrust. If this condition was bad, it might make a strong 'strobing' effect like you witnessed. If you mount a motor upside down on a stick and video it, you can see how many chunks are blowing off during the thrust phase. That's what I did anyway. 

Yes, tube support was used using pvc pipe and couple of hose clamp. My hydraulic press doesnt have a pressure guage because its just a bottle jack turned into press. Im planning to add a pressure guage anytime soon but i dont think the measurement will be correct and will have to do a conversion for the force applied. 

i might adjust the spindle length. Do you think 70:30:1 fe2o3 will work on bp spindle? All of my tooling is just diy using a stainless steel tube for the rammer and a solid for the spindle. 
 

Thanks for the suggestion. I will try to video it and check if the core is blowing chunks of the fuel grain. But as for the cracks, i think it will lead to cato rather than lift. 
 

can you suggest a good website to upload a video so i can send the link here. 

[DavidF]

The BP spindle will be too long for straight whistle. Some folks mix BP and whistle to make a hybrid rocket motor. It won't whistle, won't likely CATO, and will have more power than just BP. Another thing that's done is to press BP partway up the BP spindle, and finish with whistle. I've also pressed whistle for delay above the spindle on BP rockets, to have a whistling BP rocket (nozzleless).

Lots of folks set up a YouTube channel. It's free. Then they just post a link here. Another thing some don't know: when selecting the link, it's possible to 'copy link at current time', so the video starts playing at the spot selected instead of everybody watching a fuse burn- not that there's anything wrong with that

[PhPyro69]

 

 

 

 

[DavidF]

Yes, that sound is what folks refer to as 'raspy'. That is chunks blowing off the grain during the thrust phase. #3 was less raspy, and had the best thrust. What was done differently between the 3 rockets?

[PhPyro69]

56 minutes ago, DavidF said:

Yes, that sound is what folks refer to as 'raspy'. That is chunks blowing off the grain during the thrust phase. #3 was less raspy, and had the best thrust. What was done differently between the 3 rockets?

If chucks are blowing off does it mean that it was not pressed to the right pressure? None was done differently. The three of it is from the same batch. I think i should try with smaller increments to properly consolidate the fuel grain. I want to eliminate that raspy thrust because rocket with heavier payload will fall back down in the ground.

[DavidF]

I know that benzoate whistle is raspy and I know chunks are being blown off, but beyond that I'd just be guessing. Obviously, your pressing is inconsistent since all 3 were made the same way. Smaller increments are always suggested with whistle rockets. At least you know your whistle propellant has good potential  For rockets of that size, a small arbor press adapted to accept a click-type torque wrench is what I use. With a larger hydraulic press I use a pressure to force gauge to set the pressure cut-off. Other more creative pyros make their own PtoF gauges or tap their bottle jacks to install gauges, but that's above my pay grade. I think that website I mentioned might have a tutorial on making the PtoF gauge. You are going to need consistent pressure to get consistent performance.

As mentioned before, 4% mineral oil is quite a lot. You might try 2 1/2- 3%, and maybe also try using Vaseline or paraffin wax instead of the mineral oil. 

[FrankRizzo]

I'd refer to that popping more as "chuffing". That is usually a result of whistle fuel that has too much mineral oil or still has solvent (hasn't fully "dried").

[PhPyro69]

8 hours ago, FrankRizzo said:

I'd refer to that popping more as "chuffing". That is usually a result of whistle fuel that has too much mineral oil or still has solvent (hasn't fully "dried").

Ohh i see. But if you can check the video i sent, the three rockets were made from same whistle mix. Why is the first one differ from the rest. For the phlegmatizer, does the performance vary with different oil/wax? I heard that paraffin wax has more thrust than mineral oil and vaseline.

I will try to lower phlegmatizer down to 2.5% as davidf suggested.