# Bullet proof protection? Do we need it?

Discussion in 'Hangar Flying' started by Mac790, Jun 21, 2009.

### Help Support HomeBuiltAirplanes Forum by donating:

1. Jun 21, 2009

### Mac790

#### Well-Known Member

Joined:
Jun 22, 2008
Messages:
1,529
19
Location:
Poznan, Poland
I was cruising around the internet, and I've found a strange story at Vansairforce.net, it's about a guy whose plane had been a target for some dumb idio... He had a lot of luck a bullet missed his fuel tank by 6", and the pilot by 4'.
Full story here
Bullet Holes - VAF Forums

Seb

btw I was thinking about a few layers of Kevlar at the bottom of a plane many times, maybe it wasn't extremely silly idea.

#### Attached Files:

File size:
56.8 KB
Views:
397
• ###### bullet2.jpg
File size:
38.7 KB
Views:
368
2. Jun 21, 2009

### RonL

#### Well-Known Member

Joined:
Jan 9, 2007
Messages:
450
27
Location:
Texas
I used to have dreams of flying over the superstition mountains, with a backpack helicopter, those pictures are the very reason that dream faded into just something I would never really follow through with.:dis:

The idea of the backpack heli is still very much alive.:gig:

Ron

3. Jun 21, 2009

### pepsi71ocean

#### Well-Known Member

Joined:
Jan 31, 2009
Messages:
191
0
Location:
South New Jersey
you just need self seeling fuel tanks and some plate armor underneath the pilots seat, lol.

4. Jun 21, 2009

### RonL

#### Well-Known Member

Joined:
Jan 9, 2007
Messages:
450
27
Location:
Texas
Not sure if it was this forum (I think yes) a picture and article on how a bullet hit a rotor blade, the damage did not cause a crash, but the rotor had to be replaced.:mad2:

There are some heartless, crazy people down below.:nervous:

5. Jun 21, 2009

### Mac790

#### Well-Known Member

Joined:
Jun 22, 2008
Messages:
1,529
19
Location:
Poznan, Poland
There is a link at vans for a nice Kevlar Ballistic Panels, I've read about 10-12 similar accidents, so it seems like there are more % down below.

Seb

6. Jun 21, 2009

### Lucrum

#### Well-Known Member

Joined:
Jun 10, 2008
Messages:
955
189
Location:
Canton, GA
Too bad the FAA won't let us shoot back.

7. Jun 21, 2009

### flyranch

#### Well-Known Member

Joined:
May 19, 2009
Messages:
109
0
Location:
augusta, ga
I learned this while flying hot air balloons once, the instructor had gotten 'fired upon' many times:

The average hand held firearm (including rifles) cannot shoot vertically more than 2500 feet. There is just not enough energy in the round to make it that far. If you fly at least that high you should have no fear of ground fire.

The trouble is, most ultralight pilots like to stay around 1000 to 1500 agl.

There are exceptions, like the 50 cal., but not many people have those (wish I had one).

In the Air Force (in the early 70's), you could watch the infrared image of the rounds falling off as the enemy tried to shoot at the C-130 gunships.

8. Jun 22, 2009

### Alan Waters

#### Well-Known Member

Joined:
Jun 4, 2009
Messages:
529
79
Location:
Conover N.C.
I believe the 2500 ft max range is incorrect. As a former 1,000 yard benchrest shooter I can assure you a bullet has no trouble going 3,000 feet horizontally. I know shooters who shoot 2,500 yards on occasionally.These are big 30 cal. rifles not 50 cal.

9. Jun 23, 2009

#### Well-Known Member

Joined:
May 17, 2009
Messages:
1,434
892
Location:
Canterbury, New Zealand, Earth, Milky Way Galaxy.
I would beg to differ as will many others. There is a huge difference between the force of air slowing something down, and the force of air AND gravity slowing something down. Gravity slows the bullet at 9.8 m/s2 or 32.2 ft/s2, add to that the air resistance and you have in excess of 1G force slowing the bullet down when shooting vertically. When the bullet is flying horizontal the gravitational force is acting at 90degrees to its flight path therefore not acting to slow it down (It actually speeds it up in a different direction). All that slows a horizontal bullet is air resistance (or a solid object it hits)

Shannon.

10. Jun 23, 2009

### flyranch

#### Well-Known Member

Joined:
May 19, 2009
Messages:
109
0
Location:
augusta, ga
It's a simple physics problem. Take the mass and initial velocity of a projectile going straight up and just plug the numbers into the formula (drag out the old physics books). Bullets can go a whole lot farther horizontally than vertically. If I get the time this evening (and if I can remember, old age is a pain sometimes), I'll see if I can do a 30-06 as an example.

11. Jun 23, 2009

### Alan Waters

#### Well-Known Member

Joined:
Jun 4, 2009
Messages:
529
79
Location:
Conover N.C.
120 mm Gun M1 Anti-Aircraft Gun | World War II Database If I have made the metric conversion correctly this is what I see. A 50 pound projectile launched at 3000 feet per sec. going to an alltitude of 57,000 ft. Not hand held I admit but it makes me believe a 180 grain bullet at the same velocity would most likely make it to 8,000ft or so. Also a bullet never picks up speed after it leaves the muzzle. What would make it?

12. Jun 23, 2009

### flyranch

#### Well-Known Member

Joined:
May 19, 2009
Messages:
109
0
Location:
augusta, ga
AHHH! I may have to stand corrected on this :depressed

I quote from Yahoo

Terminal velocity ended up being about 300 feet/sec. So, it would appear that the info that my balloon instructor told me was not quite correct (at least for 30 caliber rifles).

13. Jun 23, 2009

### bmcj

#### Well-Known MemberHBA Supporter

Joined:
Apr 10, 2007
Messages:
12,704
4,704
Location:
Fresno, California
That sounds more likely to me. The high-end muzzle velocities (4-5,000 fps) would climb over 30,000 feet if gravity were the only player, but you also have to take into account normal drag and mach drag and the effects on drag if the bullet tumbles. 9,000 feet sounds like a realistic estimate.

Bruce

14. Jun 23, 2009

### Dana

#### Super Moderator

Joined:
Apr 4, 2007
Messages:
8,508
2,918
Location:
CT, USA
There was a thing a couple of years back. A guy in [IIRC] Kansas liked taking potshots at powered parachutes (PPC's) flying over his land. This was especially a problem as once a year a major PPC fly-in was held in the area. Fortunately nobody was hurt, but quite a few PPC's came back with holes. He was caught, found gulty, and sentenced to probation... and jail for one week each year for some number of years... the week of the annual fly-in. :gig:

-Dana

People are more violently opposed to fur than leather because it's safer to harass rich women than motorcycle gangs.

15. Apr 5, 2010

### lr27

#### Well-Known Member

Joined:
Nov 3, 2007
Messages:
3,216
463
The gravity is insignificant compared to the air drag. Neglecting compressibility (Mach) effects, a bullet with a terminal velocity of 300 fps that was fired at 2700 fps would have an initial deceleration of about 80 g's. That's enough to take off ALL the velocity in a little over a second, but of course the resistance goes down as it slows down.

Probably 90 percent of the energy is gone in 2,000 or 3,000 feet, though I think you'd want at least 99 percent gone!

I ran a spreadsheet which seemed to suggest that it wouldn't get even as high as 9,000 feet, though perhaps there are some other factors going on.

16. Apr 5, 2010

### Mac790

#### Well-Known Member

Joined:
Jun 22, 2008
Messages:
1,529
19
Location:
Poznan, Poland
The range is one thing, but I don't it's easy to hit a plane at 2500-3000ft.

Seb

17. Apr 6, 2010

### DarylP

#### Well-Known Member

Joined:
Mar 23, 2010
Messages:
352
0
Location:
CO
During bird hunting I stayed at 1000 feet, as the shotgun pellets would not go that high. But during deer hunting, I stayed as far away from the favorite tree stands. Unless it was bow season. :roll:

18. Apr 6, 2010

Joined:
Mar 17, 2005
Messages:
156