All-electric simulated machine gun?

[Frank Giger]

I got to thinking that a bullhorn itself might be the best solution. Self contained and built to make stuff loud, if not in high fidelity.

The only problem is that they tend to be unidirectional....but if placed behind the seat in a fabric covered aircraft facing aft, it might turn it into a drum-like amplifier (hmmm, maybe to dubious effect?).

Cutting the horn down might do the trick...

http://www.thunderpowermegaphones.co...ALL-Megaphones

[rwanttaja]

I got to thinking that a bullhorn itself might be the best solution. Self contained and built to make stuff loud, if not in high fidelity.

The only problem is that they tend to be unidirectional....but if placed behind the seat in a fabric covered aircraft facing aft, it might turn it into a drum-like amplifier (hmmm, maybe to dubious effect?).

They're cheap enough, on the link you posted...buy two, face one towards ~10 o'clock and the other towards 2 (then have 2/3rds of a Dr. Pepper, I guess). Guns are directional, too ('cept when I'm shooting) so if there's a bit of a null aft, that's not so bad.

The hard part, for any electronic solution, is going to be the tremendous drag on horns. Depending on the engine in the Nieuport, you could perhaps mount them on the firewall below the engine, "firing" through the lower open section of the horseshoe cowl.

Ron Wanttaja

[Frank Giger]

Yep, that's where it would go....on the firewall below the engine, pointed down about 30 degrees. That Nieuport is one big exercise in how to induce drag through design....no need to add to it.

Hmmm, and I am going light on the engine, so adding five to seven pounds would be okay.

[cluttonfred]

Perhaps behind the seat, angled down and forward about 45 degrees? For a WWII type, the megaphone could be disguised as a bomb on a centerline rack.

[Frank Giger]

I was actually thinking of taking the horn off of the main unit and running wire, putting the heavy bits (electronics and batteries) in the cockpit nearest the CG.

Being a skinny little guy sure does help in the W&B.

[rwanttaja]

Okay...time to put the lipstick on this pig and roll it out.

Attached is a PDF file that gives some information, and includes schematics for both circuits. Notice the previous schematic for the audio-synchronizing version had a wrong transistor call-out; this version corrects it.

Ron Wanttaja

[cluttonfred]

Bravo, Ron, thanks so much for all your work on this. Now I just need to decide whether or not I want to go with an RAF hawker Hurricane scheme for ther Taylor Mono, in which case I'll need eight, or the winter white Soviet Yak-1, in which case I'll only need two but will have to figure out how to put one in the spinner. ;-)

[danielfindling]

Okay...time to put the lipstick on this pig and roll it out.

Attached is a PDF file that gives some information, and includes schematics for both circuits. Notice the previous schematic for the audio-synchronizing version had a wrong transistor call-out; this version corrects it.

Ron Wanttaja

I think I might just have to try to build one. Thanks!

[Flyin'Bryan]

Ron and all, just when I thought I might be researching something that nobody else is really doing yet, I run into this group of like-minded individuals, and I am very happy that I did. I had to wait a day or two to get my forum account set up before I could reply. My LED adventure began with the flashing stop signs I started seeing at various intersections around town. Further research lead me to the understanding that these were most likely 3 watt high powered LEDs. Initially I was not really concerned about in-flight visibility as I was with close up on-the-ground visibility, but this thread has changed my "attitude" about that.

My next progression down this path occurred during a visit to a local Radio Shack, when I stumbled across a little Velleman minikit MK102 that has 2 flashing LEDs. It uses a pair of manually adjustable potentiometers to change the rate of either of the two LEDs, and after I soldered it all together it worked great. At that point I figured I would just need to upsize the components to handle higher powered LEDs and duplicate the same module as many times as necessary for my application. While it seem that most of you are working with the WW I gun applications, I am trying to come up with a WW II application with multiple guns firing at slightly different rates.

I then also became interested in adding some sound to the mix, and my current plan was to use a CB PA speaker (or 2) with a looped sound file on a USB stick, with the sound and light modules all wired into the trigger on the joystick. I had not even thought about the possibility of designing something that would actually synch the sound to the flash rate of the guns. Ron you have now opened my eyes to that solution so thank you for that. My current mounting plan was to attach one or two speakers to the bottom of my forward baggage compartment, with a mock grill on the outer skin that would emulate the same rectangular series of holes found on the sides of P-51 Mustang.

I currently have a test bed of a variety of different LEDs coming from Super Brite LEDs, as well as strobe controller unit that really captured my attention when I watched the video. The digital controller has 10 modes, and I am really only interested in one of them that gives a machine gun-like affect. It has a 2 amp max capacity and I was going to try to run it with 4 LEDs. Ron I really appreciate the test videos with the 5 watt light, and you now have me thinking more about in-flight visibility. I will now have to assess the ability to fit lights that are bright enough but may be a challenge to fit into an in-wing gun port installation for my application. All really great stuff on this thread. Looking forward to the sound tests!

[rwanttaja]

Ron and all, just when I thought I might be researching something that nobody else is really doing yet, I run into this group of like-minded individuals....

Good to hear from you, Bryan. Hate to start out with a spelling flame, but I have to point out that "Stupid half-mad b******s" is NOT spelled, "like-minded individuals." :-)

Thanks for your insights and the results of your own research/experiments. One of the things we also haven't considered much is the *directivity* of the light emission. Most of these systems concentrate light in one direction, which means that only the people within ~20-30 degrees of the boresight get the full-power flash. There are really few instances where we would be flying directly at the people on the ground who we want to see the flash.

Guys with the WWI replicas might consider putting their high-power LEDs on adjustable mounts. If you're going to be doing low passes with the crowd on the left, set the LED to point ~45 degrees in that direction. Looks bad close-up, but sure should be more visible to the general (Shakespearian term, doncha know).

Your point about the multiple guns in a WWII fighter not be synchronized is a good one. We're all, again, attuned to the Hollywood machine gun sound, where eight .30 calibers make a single rat-tat-tat sound.

The nice thing is, with those flashers using the 555 timer, the natural variation in the values of the resistors and capacitors will make the firing rates slightly different. If the capacitor value varies by just a 10% variation, that changes the firing rate by nearly 50 rounds per minute! So any two circuits side-by-side are NOT going to sync up, and will be discordant just like a real set of guns.

Along that note, they make a single IC (the 558) that includes *four* of the 555 timers. So a single chip could provide four slightly different gun flashes. You'd still need separate power transistors for each one, of course.

Ron Wanttaja