>>> Is there such a thing as a rocket opening parachute?
>>>
>>> In other words a rocket attached to a metal static line that pulls a
>>> parachute out of a bag and makes it open almost instantaneously?
>>>
>>>
>>> I am thinking of safe ways of testing a tilt rotor aircraft.
>>>
>>> Paul Lamar ...No rotor no motor.
>>
>> Paul... isn't that precisely what the BRS (ballistic recovery system)
>> is all about... a ballistic deployment, a slider ring to accommodate
>> fast vs. slow
>> speed filling of the chute.   ????  am I missing something here???
>>
>> Gary Buster
>> N263GB
>> Tyler Texas
>>
>> I am not sure. I don't know how it works.
>>
>> I would not necessarily like to save the airplane. Just the pilot
>> from and open cockpit.
>>
>> --
>> Paul Lamar ...No rotor no motor.
>
> Paul
>
>
> Yep,  I still have the rocket and switch from one of the first units
> BRS made for an ultralight I brought into Japan 25 years ago.  Never

used

it.
> The solid propellant rocket is about shaped in an aluminum pipe is 1.5
> inches in dia and 6 inches long with a rubber nose cone. A kevlar
> strap attaches to the chute and to the rockets stainless wire bridle.
> You wouldn't not want to attach this to a person's harness for reasons
> of sudden stress and the fact that opening a parachute outside the
> plane with the person inside usually results in the person and plane
> being destroyed.
> Better to bring your whole plane down as the pilot has more protection
> from the structure.
>
> My brother was lucky last year when he was flying and one of his jump
> instructors let her pilot chute go out the open door.  All of her
> students gracefully kicked her out of the plane and followed in mass
> shortly after.
> Airplane do not usually survive such an event.  Her partially open
> chute took off the C-182'2 right stabilizer and elevator before she
> was able to cut away.  Somehow he was able to land safely using a
> burst of throttle before contact.
>
>
> Doug Fir
>
> Wow.
>
> I'll have to think this thing through. The big problem is making sure
> the rocket points as straight up as possible with out fouling the
> rotor. Maybe I need a guidance system of some sort in the rocket.
>
> Paul Lamar ...No rotor no motor.

Hi Paul, didn't the Germans in WWII and later the Soviets tackle this
problem already with the rear prop fighter (DE) and the helicopters with
ejection seats (RU) ? I thought they both had explosive bolts on the

blades

for when the pilot bailed.

-dave

That sounds good.
--
Paul Lamar ...No rotor no motor.


This is a good article on ejection seats and systems.   Having experienced

a

"controlled" ejection myself I can attest to their efficacy if not

comfort.

They are tricky animals since they have to deal with all kinds of aspects,
speeds altitudes and bodies.  The current generation of ejection seats

have

their own sensors to determine ejection parameters since the new

generation

of fighters have such a large flight envelope.

I think the extraction systems are the best for single seat or tandem seat
configurations.   They were never really developed since we shifted to
supersonic fighters about the time they were deployed.  The reason I think
an extractor would work is because it would be easy to design an extractor
with the best of the BRS systems patent (slider ring) and the

Yankee/Ranger

system.   As far as the part about disconnecting the pilot from the

aircraft

that can be done with pull pins on the harness just like the Martin Baker
seat does.  As the static line stretches above you it releases the harness
just before it pulls out the pilot.  As far as the shock of the motor is
concerned I can tell you from first hand experience it's not as bad as you
think because the rocket is working on a lot of things before it gets to

the

pilot's butt.  It's a matter of sizing the motor for the job.

Here is a nice discussion

http://showcase.netins.net/web/herker/ejection/eject_paper.html

-Ben

I have not experienced an ejection, however, I can tell you from experience
that ejection seats have to be and are *hard*.  If they weren't, the seat,
when fired, would compress the foam cushion and slam into your butt with
great force and cause injury to your spine.  Even when used correctly they
can injure the pilot - I know someone who was and I am sure Ben has heard of
others.  There are live ejection seats in the civil realm - I know because I
took a ride in an L-39 a couple years ago, however, there is some difficulty
in storing a live ejection seat in a hangar.  If you ever need to remove it
for any reason the BATF wants you to have it in a locked up facility among
other things.  The seats are hard, heavy and expensive.  And that was a
relatively unreliable Russian make.  Martin Baker in the UK and Goodrich in
Colorado Springs, CO make the best IMHO.  But be ready to pay some big $ -
that is, and this is crucial- *if* they will sell you one.

I have not heard of an extraction system before this.  It sounds
interesting - less expensive, and lighter.  The question is, will it work??
Can you avoid the rotor blades? Just some thoughts on it...

Norm

Well there is another possible path and that is air bags. Big for the whole
airplane or small for just the pilot.

Paul Lamar

A person in free fall reaches a speed of about 150 FPS. If he can stop
in only 15 feet that would be 47 G's If my math is correct.

Distance = feet  = FPS x seconds
Acceleration = FPS per second = FPS/seconds

Solving for seconds.
15 = 150 x seconds

15/150 = .1 seconds

Acceleration = FPS per second = 150/.1 = 1500 FPS per second or 47 G's

People have survived impacts of 47 G's. This is worst case from a high altitude.

In a vacuum a person will accelerate after leaving an aircraft at 32 feet
per second per second.  Less due to air drag. First second he reaches
32 FPS. Second second he is doing 64 FPS. Third second he is doing
96 FPS or 65 MPH. Drag will now start to significantly decrease
his acceleration.

Acceleration = FPS per second = FPS/seconds
100 = FPS x seconds >>>> FPS = 100/seconds
32 = FPS/ seconds.  >>>> FPS = 32 x seconds

100/seconds = 32 X seconds

100 = 32 x seconds x seconds

100/32 = seconds^2
3.125 = seconds ^2
seconds = square root of 3.125 = 1.76 seconds before you hit the ground
I think.

FPS is then 32 x 1.76 or 56 FPS per second.

56 FPS x 1.76 seconds is 98 FPS per second or 3 G's.

(One G is 32 FPS per second.)

If my math is correct. So if you are over 100 feet up you need
a parachute but if you are less than 100 feet where a parachute is
unlikely to work (even rocket assisted) maybe what we want is
a 15 foot thick air bag that inflates in a small fraction of a second.
Could be activated by a lead weight switch on the end of a dangling 20 foot
wire. The pilots body orientation could be handled by a small drogue
chute.

Looks like both parachute and air bag would be a good idea for a helicopter
or tilt rotor test pilot.

Check my physics and math. I'll redo this with a QB program for
other than 100 foot altitudes.

For tether testing a swivel fitting could be used on the end of
the mast and a large crane to prevent heavy impacts up to 50 feet or
so. There then must be a large wire cage around the rotor
to prevent fouling of the tether.