RE: 2 death 4 wounded in model airplane crash

RE: 2 death 4 wounded in model airplane crash
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RE: 2 death 4 wounded in model airplane crash - 5/15/2006 9:57:17 PM

ravill

Posts: 1915
Joined: 1/24/2003
From: Redwood, CA, USA
Status: offline

After reading this, I have been moved to add another layer of safety to my blossoming turbine career. Just as I have a spare pair of hearing guards, I will go straight to wal-mart and buy an air powered blow horn to hand to my spotter along with the hearing protection......

After being dumbfounded at watching my turbine fall into the ground (engine was shut off when model was deemed uncontrollable) I was soooooo relieved that no one got hurt. I learned many lessons that day and today I have learned a few more. I will set all my prop airplanes to engine off with failsafe.

Just for thought, what if, we could make a speed and altitude limited parachute deployment upon failsafe? A speed sensor can be bought from jetcat. A gps that senses altitude is also available. Yes, these are expensive (cheaper technology is out there, just look at some of those awsome casio watches...) but, I would pay $400 to save anyones life! Even those people on RCU that just love to start fights!!!

With some luck, the parachute would slow the model down giving it a more predictable trajectory and if just tore the airplane in pieces, then maybe the resulting increase in cross section, would slow the pieces down.....But again, if this were to happen among a group of spectators, then this would transform one falling piece into many falling pieces, albiet smaller pieces with less mass!!

I wish I had the capitol, ingenuity and the time to design something like this. From what I've been able to gather, when these turbines go into failsafe, there is not much we can do to save them anyways.....

I suppose a solution would be to set failsafe to snap with a parachute deployment....The snap would slow the airplane down and the parachute would give it a predictable trajectory....

Hey, I think I'm on to something!!!

sorry, I'm just rambling...

But, truthfully, every flying day should be a day in which we can scrutinize, atleast, our own behavior into a safer one. Safe and happy flying to all.

Raf

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RAVjets Demo Team. All We Do Is Fly.

(in reply to pcsol)

Post #: 76

RE: 2 death 4 wounded in model airplane crash - 5/15/2006 10:03:13 PM

Gordon Mc

Posts: 6709
Joined: 1/30/2002
From: San Jose, CA,
Status: offline

quote:

ORIGINAL: paf
A PCM failsafe to kill/idle an engine is a desirable feature and should be demonstrated at every event involving large number of people. However, that in its own will not prevent accidents - looking at the hungarian video, it would have made no difference there

On what basis do you make such a claim ?

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"He who establishes his argument by noise and command shows that his reason is weak." - Michel de Montaigne

(in reply to paf)

Post #: 77

RE: 2 death 4 wounded in model airplane crash - 5/15/2006 11:27:44 PM

paf

Posts: 79
Joined: 11/20/2002
From: New York, NY, USA
Status: offline

quote:

ORIGINAL: Gordon Mc

quote:

ORIGINAL: paf
A PCM failsafe to kill/idle an engine is a desirable feature and should be demonstrated at every event involving large number of people. However, that in its own will not prevent accidents - looking at the hungarian video, it would have made no difference there

On what basis do you make such a claim ?

To me, the model seems to have went out of control approximately 5 seconds before impact. That's not enough time to bleed off enough kinetic energy to make it non-lethal, even with the engine at idle. However that's no excuse for anyone to not have a PCM failsafe go to idle.

To me, the main reason for PCM failsafe is to prevent energy buildup when uncontrolable model flying at high altitude gets into a nose down attitude with WOT. It's not a cure-all.

P.

P.S.
Did anybody notice the ING commercial shown just prior to the accident report with kids peacufully flying model gliders ???

(in reply to Gordon Mc)

Post #: 78

RE: 2 death 4 wounded in model airplane crash - 5/15/2006 11:29:08 PM

Woketman

Posts: 4005
Joined: 12/6/2001
From: Slidell, LA, USA
Status: offline

ING commercial? What video link were you looking at? Please post.

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(in reply to paf)

Post #: 79

RE: 2 death 4 wounded in model airplane crash - 5/15/2006 11:34:47 PM

paf

Posts: 79
Joined: 11/20/2002
From: New York, NY, USA
Status: offline

quote:

ORIGINAL: Woketman

ING commercial? What video link were you looking at? Please post.

It was posted on the first page of the thread:

mms://stream.publishing.hu:1755/tv2/video/tenyek/tenyek_0513_low.wmv

(in reply to Woketman)

Post #: 80

RE: 2 death 4 wounded in model airplane crash - 5/15/2006 11:40:36 PM

Gordon Mc

Posts: 6709
Joined: 1/30/2002
From: San Jose, CA,
Status: offline

quote:

ORIGINAL: paf

To me, the model seems to have went out of control approximately 5 seconds before impact. That's not enough time to bleed off enough kinetic energy to make it non-lethal, even with the engine at idle. However that's no excuse for anyone to not have a PCM failsafe go to idle.

5 seconds is more than enough time to stop a prop by having failsafe set to engine kill

_____________________________

"Facts do not cease to exist because they are ignored." - Aldous Huxley
"He who establishes his argument by noise and command shows that his reason is weak." - Michel de Montaigne

(in reply to paf)

Post #: 81

RE: 2 death 4 wounded in model airplane crash - 5/15/2006 11:57:42 PM

EddieWeeks

Posts: 1131
Joined: 12/27/2001
From: Baton Rouge, LA, USA
Status: offline

I switched back to PPM 10 years ago and I am much happier with it... I did crash a jet
with the PPM in Deland but I had some control all the way to the ground.

I get a lot more bumps and hits than everyone else but I see them all and when I get
two in a flight I land... no big deal...

I can't say if PPM (FM) would have helped in this case, but if it was like my crash he would
have %50 control at first.... Then %20... more than enough time to chop the power and
have the engine power back.. Way better than lock out at full power...

Eddie Weeks

(in reply to Gordon Mc)

Post #: 82

RE: 2 death 4 wounded in model airplane crash - 5/16/2006 12:02:19 AM

EASYTIGER

Posts: 7676
Joined: 12/7/2001
From: nyc, NY, USA
Status: offline

quote:

ORIGINAL: EddieWeeks

I switched back to PPM 10 years ago and I am much happier with it... I did crash a jet
with the PPM in Deland but I had some control all the way to the ground.

I get a lot more bumps and hits than everyone else but I see them all and when I get
two in a flight I land... no big deal...

I can't say if PPM (FM) would have helped in this case, but if it was like my crash he would
have %50 control at first.... Then %20... more than enough time to chop the power and
have the engine power back.. Way better than lock out at full power...

Eddie Weeks

I thought I was the last person on the planet to not belive in PCM. I fly PPM, and don't plan to change. I will gladly change to spread spectrum pretty soon, when that gets refined. But if I did fly PCM, the failsafe would be set to kill the engine! Anything else is nuts.

(in reply to EddieWeeks)

Post #: 83

RE: 2 death 4 wounded in model airplane crash - 5/16/2006 12:17:45 AM

EddieWeeks

Posts: 1131
Joined: 12/27/2001
From: Baton Rouge, LA, USA
Status: offline

The funny thing is, when I range check my plane, with the engine running (PPM) I walk
until things start to chatter, and the engine quits right away sometimes... as the receiver gets
bad frames, it only takes one frame where the engine run channel goes to the stop engine... and
the engine quits... Also.. If I turn the transmitter off... The turbines quits right away.. A sec or less...
If the AMT ECU quits getting frames it shuts down really fast... The IPD system with multiplex is very
similar. Something to think about... I don't think if anyone will change back to PPM because it requires
less expensive radio gear...
Eddie Weeks

< Message edited by EddieWeeks -- 5/16/2006 12:23:44 AM >

(in reply to EASYTIGER)

Post #: 84

RE: 2 death 4 wounded in model airplane crash - 5/16/2006 12:20:55 AM

wojtek

Posts: 3017
Joined: 12/25/2001
From: old bridge, NJ, USA
Status: offline

quote:

I doute if anyone will chage back to PPM because it requires
less expensive radio gear...

lol ...

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Post #: 85

RE: 2 death 4 wounded in model airplane crash - 5/16/2006 12:26:11 AM

paf

Posts: 79
Joined: 11/20/2002
From: New York, NY, USA
Status: offline

quote:

ORIGINAL: Gordon Mc

quote:

ORIGINAL: paf

To me, the model seems to have went out of control approximately 5 seconds before impact. That's not enough time to bleed off enough kinetic energy to make it non-lethal, even with the engine at idle. However that's no excuse for anyone to not have a PCM failsafe go to idle.

5 seconds is more than enough time to stop a prop by having failsafe set to engine kill

From my experience (failed throttle servo, killing the engine using electronic kill switch in order to land), it takes around 15 seconds for a 32x10 CF prop to actually come to a stop during level flight.

20kg model at 80 mph (33 m/s) has 10890 J kinetic energy. Your average, relatively high-drag, giant scale model will slow down to approx. 55mph (23m/s) in 5 seconds, dropping the energy down to 5290 J.

A 32" prop has has moment of intertia approx. 0.025 kg/m^2, so spinning it at 5000 RPM gives you 3152 J kinetic energy.

A 9mm bullet right at the nozzle has approx. 500 J kinetic energy.

Either scenario is a losing proposition.

Although not intuitive, you're better off falling into a stationary 32" prop at 5000 RPMs rather than getting hit by 20kg glider at 55mph. Your worst nighmare (like the accident in question) is a spinning prop on a nose of a heavy airplane

P.

(in reply to Gordon Mc)

Post #: 86

RE: 2 death 4 wounded in model airplane crash - 5/16/2006 1:58:41 AM

causeitflies

Posts: 226
Joined: 1/1/2003
From: Steubenville, OH, USA
Status: online

15 seconds!? That's a loong time. My 26" prop stops in about 5 seconds.
Sounds like you need a set of rings

_____________________________

Mark P
An Expert has made every mistake - A Master has made every mistake twice

(in reply to paf)

Post #: 87

RE: 2 death 4 wounded in model airplane crash - 5/16/2006 2:12:38 AM

ghost_rider

Posts: 4265
Joined: 12/11/2001
From: Ft Wayne, IN, USA
Status: offline

It is said that “Charity beings at home” and such how many of you that have attended a jet event this year
had your AMA engine kill checked by the club or event organizer?

We should make it a must at every major / non-major jet event with no exceptions.

_____________________________

.....ghost_rider....out....
AMA 9119
“Beware of your so called friends because you know your enemies”

(in reply to paf)

Post #: 88

RE: 2 death 4 wounded in model airplane crash - 5/16/2006 2:24:38 AM