Mar 8 update Whistler---Mimi and Nerf Football Whistles

Gary Byrum was doing something called the "Whizzler" but never saw the final outcome
https://www.rocketryforum.com/showthread.php?58981-The-Whizzler&highlight=whizzer

Was thinking about something that probably already has been done, so this is exploration.
If you put a REAL coach's type whistle on a rocket, ducted the flow to create increased pressure at the inlet, would you hear an audible sound? Do you need to put a diverter or guard over the OPENING of the whistle to prevent the airflow over the whistle from distorting or muffling the sound? What kind of whistle was used in the screaming Mimi (I've read mixed reviews on whether it really worked or not.)

my tests have shown that, you need a short burn motor(cause you can't hear anything over the sound of the motor). basically you need to get the rocket up to speed, then you need the motor to shut up at a reasonably low altitude so you can hear the whistle. HTH
Rex

Hi Tom,
I'll be watching this one!
I've tried a few times to get a "whistler" using LPR engines.
If anybody can get it to work - you will!

A metal whistle might be louder, a plastic whistle is much lighter.
It'll take a lot of directed airflow to get it to blow tho -

Rex R is right, you'd only hear a whistle after the louder thrusting portion of the engine burn.
MPR models with split fins seem to whistle the most.

I've never heard a Estes Screaming Mimi whistle.
Every time one is launched we all pause and listen - nothing!

Agree with both Rex and Chris:
Last November for my 65th Birthday I designed and flew a 4-D12-3 Clustered Rocket with 6 Plastic whistles and 3 Fin mounted Sirens. NONE could be heard over the roar of the motors. Was a very KEWL flight anyway

Ducting the airflow directly into the whistle could certainly help, if you could start the duct with say 1/3 of the area around the model reduced to just fit the mouth of the whistle. I'm sure you would still need a high thurst short burn motor as everyone has said to actually hear the whistle.

Thanks gents.
If it wasn't for the safety issues, the solution would be launch to apogee, let return partway ballistic to pick up speed to feed the whistle, and have the thing deploy about 100 feet AGL.

Hey Tom. The Whizzler is like all of my rocketry right now. I haven't done much of anything over the winter months. Too chilly outside for me to sand anything and I can't do that inside the house. Especially when sanding putty coats for finishing. I will get that bird finished at some point and will pick up where I left off. I feel like you do in regards to ducting the air and since the Whizzler is cone shaped, it should keep it from flying too fast. Speed could seize the siren whistles so I am hopeful my take on it will work. I'd be real interested in knowing how your approach plays out.

Okay, here's the rocket

The scoop is a BurgerKing Plastic cup cut into a funnel shape.
It is attached by two struts, the one on the actual whistle side has a gap near the whistle so that air from both sides of the strut can reach the mouthpiece of the whistle.
The shock cord is attached to the tail of the rocket (actually the base of one of the fins.) With streamer recovery it is possible the descent rate will still be sufficient to blow the whistle.
Plan is for launch with an A8-3. Should be a very short propellent burn followed by an otherwise silent (from engine standpoint) ascent.
Some of the pictures have the launch rod in place, the lug is outside the rocket body but inside the scoop.

Design not really RockSimable (one of these days I guess I should actually buy the program) for obvious reasons.
However, CG with the nose weight I have added and C6 engine is FORWARD of the scoop, so should easily be stable on the A8-3,
Hope to fly it Wednesday.

couple more pics. Also note that you can see the shock cord running along the side of the rocket on pic 2 of previous post

I'm looking forward to the flight results!
Hoping for a LOUD whistle.
Good Luck!

I'm actually working on something similar except I'm looking for a certain whistle to even get started.

Does anyone remember the Nerf Vortex football that had the screaming whistles? They are very loud when high speed air moves over them.

I used to mess with my brother in the shop and hook the air hose to them from the shop compressor.... Deafening.


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Joker050608 said:

I'm actually working on something similar except I'm looking for a certain whistle to even get started.

Does anyone remember the Nerf Vortex football that had the screaming whistles? They are very loud when high speed air moves over them.

I used to mess with my brother in the shop and hook the air hose to them from the shop compressor.... Deafening.


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Click to expand...

is this what you're thinking of

https://www.amazon.com/dp/B004XMVZVY/?tag=skimlinks_replacement-20

Here's a thought. If neither of us succeeds in getting our whistling rockets to sound off, maybe looking into these loud easy blow Stadium Horns.



https://www.gotparty.com/horns.htm

Gary Byrum said:

Here's a thought. If neither of us succeeds in getting our whistling rockets to sound off, maybe looking into these loud easy blow Stadium Horns.

View attachment 163419

https://www.gotparty.com/horns.htm

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Only problem with them is that you have to buzz your lips like you were playing a trumpet fo them to work. just blowing into the will not do anything.

conman13 said:

Only problem with them is that you have to buzz your lips like you were playing a trumpet fo them to work. just blowing into the will not do anything.

Click to expand...

I didn't know that....SHUCKS! Well Tom, may the best whistle win. I simply can't think of another worthy whistle besides what the two we're using.

That whistle on the nerf vortex football actually appears to be EXACTLY what i want. Not sure if i want to pay $17 for one. Chris (Banjo) what exactly did the screaming mimi use for a whistle?

Hi Tom,
I don't know for sure, I never built a Screamin' Mimi.
I have seen them fly tho - The whistles were something like these:


https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=Siren whistles

Instructions are here:
https://plans.rocketshoppe.com/estes/est2185/est2185.pdf

In the few Screamin Mimi flights I've seen, there wasn't a whistle.
Lots of spectators listened for it, but nothing.
I think you are on the right track tho. Directing the airflow might be the way to go.

The whistle on the Nerf football requires a hollow area directly behind the whistle head.
I bought a whistle rocket at WalMart thinking I could remove it an glue it on a standard rocket.
It has a whistle much like the Nerf football does.
The hollow air chamber inside would require a 1/2" hole horizontally through the body tube.



When "launched" with the compressed air handle it wasn't loud.
I gave up and threw it away.

Why not use the main body tube itself as the whistle chamber? Lop a bit off the end off the nose cone for air flow, install a balsa plug in the base with a flat sanded on it, and cut a whistle notch in the body tube? Kinda hard to describe, but my prototype works at 65 mph going down the highway! :wink: Just a basic 3fnc, (basically a smaller diameter Alpha III-using BT-20 instead of 50). I just took a whistle design from the Instructables site and modified to a rocket.

It's small enough for tumble recovery, the nose cone is glued in and the ejection gases exit through the whistle opening. A quick drawing so it makes more sense.

Or, you could add pods of the same design (bottom ends plugged) and use standard recovery methods.

Just a thought...:confused2:

ThomasL said:

Why not use the main body tube itself as the whistle chamber? Lop a bit off the end off the nose cone for air flow, install a balsa plug in the base with a flat sanded on it, and cut a whistle notch in the body tube? Kinda hard to describe, but my prototype works at 65 mph going down the highway! :wink: Just a basic 3fnc, (basically a smaller diameter Alpha III-using BT-20 instead of 50). I just took a whistle design from the Instructables site and modified to a rocket.

It's small enough for tumble recovery, the nose cone is glued in and the ejection gases exit through the whistle opening. A quick drawing so it makes more sense.

Or, you could add pods of the same design (bottom ends plugged) and use standard recovery methods.

Just a thought...:confused2:

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great thought. Trying to be clear from drawing. Air comes in thru nosecone, passes through the edge cutout of the bulkhead, and then out thru the notch of the body tube? Is the cut out of the blue bulkhead directly adjacent to the notch?

This would work great with rear ejection?

Chris, can do you have any diagrams of the whistle you are talking about? I am thinking it might not be that hard to fashion out of balsa.

Thanks guys.

BABAR said:

is this what you're thinking of

https://www.amazon.com/dp/B004XMVZVY/?tag=skimlinks_replacement-20

Click to expand...

That's exactly what I'm talking about. I need these. Thanks


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BABAR said:

great thought. Trying to be clear from drawing. Air comes in thru nosecone, passes through the edge cutout of the bulkhead, and then out thru the notch of the body tube? Is the cut out of the blue bulkhead directly adjacent to the notch?

This would work great with rear ejection?

Chris, can do you have any diagrams of the whistle you are talking about? I am thinking it might not be that hard to fashion out of balsa.

Thanks guys.

Click to expand...

You can vary where the plug sits, but it seems to work best with the trailing edge at or just slightly (maybe 2-3mm) in front of the vertical cut in the bt. My proto has a plug the length of the shoulder, and the vertical cut is about 3mm behind the bottom edge of the nc shoulder.

I forgot to mention that the flat on the plug MUST be in line with the notch. Another hard to explain visualization- The bt is laying on the table, with the notch up. The flat on the plug is facing up also. The air coming through the sanded flat passage has to hit the apex of the notch cutout-that's what makes the whistle. The pitch of the whistle is mostly determined by the length of the bt. Maybe you can get a better idea from this- www.instructables.com/id/Simple-PVC-Whistle/

Hadn't considered rear ejection-good idea! :grin:

I'm doing a build thread with rear ejection. Mine is a hpr though. Can't wait to get it finished and see it take flight.


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ThomasL said:

Why not use the main body tube itself as the whistle chamber? Lop a bit off the end off the nose cone for air flow, install a balsa plug in the base with a flat sanded on it, and cut a whistle notch in the body tube? Kinda hard to describe, but my prototype works at 65 mph going down the highway! :wink: Just a basic 3fnc, (basically a smaller diameter Alpha III-using BT-20 instead of 50). I just took a whistle design from the Instructables site and modified to a rocket.
It's small enough for tumble recovery, the nose cone is glued in and the ejection gases exit through the whistle opening. A quick drawing so it makes more sense.
Or, you could add pods of the same design (bottom ends plugged) and use standard recovery methods.
Just a thought...:confused2:
View attachment 163451

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A Ramjet! This might be the answer right here!
I could bet between you and Babar (Tom) somebody will get a loud enough whistle going up!

I would lengthen the body and make the whistle area as a payload section.
There could be another balsa coupler below the notch.
The farther down the couple, the lower the whistle note.
That way you could have a standard parachute ejection.

hcmbanjo said:

A Ramjet! This might be the answer right here!
I could bet between you and Babar (Tom) somebody will get a loud enough whistle going up!

I would lengthen the body and make the whistle area as a payload section.
There could be another balsa coupler below the notch.
The farther down the couple, the lower the whistle note.
That way you could have a standard parachute ejection.

Click to expand...

Excellent idea Chris! (I probably would have gotten there later than sooner with plenty of wasted materials-you saved a bunch of time and $$$!)

Something along these lines-

As you mentioned, the length of the payload section (I call it the whistler tube), determines the whistle pitch. I just quickly threw the idea together in OR to get the idea, so there's no real set lengths yet. A lot of the dimensions will be determined by the stability that OR gives me.

One thing to stress, is that a lot of trial and error experimentation needs to be done to get the sound right. I test mine at 65mph with my hand stuck out the window of the car. (No, I'm not driving-I'm the passenger ). I found there's a HUGE difference between just blowing into the assembly and testing it at higher air velocities going through the port!

I'm still toying with the external pods idea-have 2 or 3 assembly's, possibly slightly varying lengths for different tones? R&D is kinda at a standstill right now-waiting on the IRS to send me my tax $$$, but will definitely keep everybody posted!

Thanks for the ideas guys-saved a lot of head-scratching!

Thomas

My of my later plans (never built) was to have three whistle tubes and have a lower solid coupler that could slide up and down to change the pitch.
Once tuned to a Major triad (Do - Mi - So) the coupler plugs would be glued in place.
I was going to call it the Calliope.

hcmbanjo said:

My of my later plans (never built) was to have three whistle tubes and have a lower solid coupler that could slide up and down to change the pitch.
Once tuned to a Major triad (Do - Mi - So) the coupler plugs would be glued in place.
I was going to call it the Calliope.

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Great idea (and name)!!!

That would work a lot better than tubes of varying lengths for balance, stability & cosmetic reasons.

I'm thinking a BT-60 main with three 50's for the whistle tubes... I wouldn't be able to tune the whistle pods (maybe ship them to you and let you tune them before I glued them to the main tube (hint, hint ). The only issue I foresee would be getting the tubes tuned with the approximate airspeed the rocket will be hitting on the ascent.

I've built the same setup, with two of the tubes ducted for rear chute deployment (a take on the Estes Gemini DC).

I'm definitely switching thought trains and going with your idea of the payload compartment for further testing before I commit to the pod idea though. I have an older Alpha I can use as a test platform, so I won't be out much if it doesn't work like it's supposed to in theory. :wink:

Will keep you informed!

Thomas

ThomasL said:

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Something tells me your nose isn't going to sim very well. I am guessing it is going to be pretty draggy. Makes the idea of tail pods sound more practical.

I am still wondering if the air flow over the vent is going to distort the sound.
Where is a wind tunnel when you need one? Not sure sticking it out the car window is an approved NAR activity (but clever none the less.)


Going back outside the box, what about a rocket intended to come in ballistic with a fixed tennis ball or nerf ball nose cone? You would hear the whistle coming in. For safety purposes you could separate the nose and whistle off so it isn't too heavy. Throw a streamer in back to maintain ball down orientation. Fin can and motor recover with chute.

Would reaaaaaaalllly be cool to tune your calliope to a train whistle!

Ah well, getting a bit ahead. Let me see how the "Whistler" flies and sounds tomorrow!

BABAR said:

Something tells me your nose isn't going to sim very well. I am guessing it is going to be pretty draggy. Makes the idea of tail pods sound more practical.

I am still wondering if the air flow over the vent is going to distort the sound.
Where is a wind tunnel when you need one? Not sure sticking it out the car window is an approved NAR activity (but clever none the less.)


Going back outside the box, what about a rocket intended to come in ballistic with a fixed tennis ball or nerf ball nose cone? You would hear the whistle coming in. For safety purposes you could separate the nose and whistle off so it isn't too heavy. Throw a streamer in back to maintain ball down orientation. Fin can and motor recover with chute.

Would reaaaaaaalllly be cool to tune your calliope to a train whistle!

Ah well, getting a bit ahead. Let me see how the "Whistler" flies and sounds tomorrow!

Click to expand...

Tom-

No, the nose doesn't sim at all-I haven't found a way to have a flat-topped, hollow nc. And only having OpenRocket, I can't sim the external pods idea since they aren't supported, but I'm guessing it would sim three times as draggy since there's three truncated nose cones.

As far as the air going over the vent distorting the sound, it's quite the opposite-that's what MAKES the whistle. It's the same principle as using a blade of grass, or a reed in a musical instrument. That cut out notch IS effectively the reed-without it, it would be soundless.

I'm not sure holding a rocket out the window for air tunnel simulation violates any NAR rules or recommendations , but I AM pretty certain that flying a rocket to intentionally come in ballistic shatters at least a few in the safety code!

Have a small section of BT-20 I'm playing with. If I get a chance tonight, I'll see if I can get a short vid uploaded. I might have a chance this coming Saturday to try Chris' payload section idea-will let you know!

Thomas

This is certainly a creative brainstorming thread!
For experiment purposes I have found a 1/2 inch dowel makes a pretty good "plug" in a BT-5 body tube.

Are we talking two different kinds of whistles here? The "classic" whistle seems to be a horizontal flat tube that opens out to a chamber with a vent over it. I have just been playing with the BT-5 and dowel plug with one edge flattened with sandpaper. But you have to blow into the front.

Is there a second Whistle which makes sound just from air passing over it? And does anybody have a diagram of it?

BABAR said:

This is certainly a creative brainstorming thread!
For experiment purposes I have found a 1/2 inch dowel makes a pretty good "plug" in a BT-5 body tube.

Are we talking two different kinds of whistles here? The "classic" whistle seems to be a horizontal flat tube that opens out to a chamber with a vent over it. I have just been playing with the BT-5 and dowel plug with one edge flattened with sandpaper. But you have to blow into the front.

Is there a second Whistle which makes sound just from air passing over it? And does anybody have a diagram of it?

Click to expand...

Sure there is-it's a pop bottle of jug! It uses what's called the "Helmholtz resonance" (the differences in air pressure and the air oscillations-had to look it up in Wiki :wink: ). Wiki actually has a pretty good description of whistles and a few different types.

Anyway, here's some pics. One thing I've found that's crucial is the size of the flat on the plug. Too little of a gap and air won't pass over the notch fast enough to produce a sound, and too large of a gap causes too much turbulence and once again, no sound is produced. Mine was too toom, so I had to CA a few thickness of heavy paper stock on it to get a good sound.



Any ideas how to attach a short video that's not a YouTube? It's a small (12.5K) .MOV file. Tried it as an attachment, but TRF said it was an invalid file type.

Thomas