bidrseed2

My Feedback: (2)

Hi all,

Our club has recently placed restrictions on flying of large petrol models. An outright ban was suggested, later a phased ban and finally a restriction on the the number of large model flyers allowed.
( 10 members, or 5%)

the reasons spouted were initially initimidation of other flyers, then noise, then model presence. Finally site security was given and as these models were a threat to the site ( in some members opinion) then any action was being justified.

Including not renewing memberships of certain individuals.

I digress, but right now there are two jet flyers in the club. There are another three modellers building jets and my concern is that at some time in the future, jets will be the new nemesis.

Our field is surrounded by crop fields and we do have a club rule about "not overflying ripe corn fields"
Its inpractical not to overfly so this is effectivelly a ban at certain times of the year.

The time of the year when the crops are "ripe" is subjective, and another club member who has nothing to gain from my flight may feel that the risk of flying jets is too high much earlier in the year compared to myself.



This is presumably due to the percieved fire risk, as every jet crash on youtude results in a spectacualr fireball.

Its all risk management as lipos COULD cause a fire also, but are not seen as much of a risk.

Ive been attending jet meets for 5 years now and can recall seeing fifteen crashes. Only one caused a fire.

So my questions are


a) Out of all the crashes, what fraction/percentage result in fires.

b) Does model size determine fire risk- eg is a Wren 44 model as likely as 30lb thrust model including its 4l of fuel.

c) When a model crashs in crop fields, do we know of fires spreading beyond the immediate area.


I need your guys experiences good and bad so that Im armed with information when this debate arises.

Im also keen to avoid a confrontation as occured over the large model debacle so would like to pre empt this debate.


Im also keen to empasise that stating odds of fires may be used by other parties who do not share our interests, so if you dont feel that posting replies on a public forum serves the jet communitys interests please pm me.

It has come to my attention that some of my comments, while intended in the spirit of jocularity, would appear to have caused offence to some club members. So i apologise to anyone offended with these comments.

jason

My Feedback: (1)

I have seen a good few 44 powered L39's crash and not puff of smoke in sight but on the other hand I have seen plenty of Hotspots crash and they all seemed to burn, maybe because they normally have a big engine that sits behind a big fuel tank. So I think you can reduce the chance of a fire following a crash by what you fly. But in saying that, I would never knowingly fly over dry crops.


I remember a couple of years ago a guy crashed a big boomer in a dry field at a European jet meet, there was a 10 ish MPH wind and it set fire to the field big time. Thankfully the organisers of the Jet meet had the forward thinking to have a fully equipped fire engine and crew on hand but even they only just managed to put the fire out when the fire went as far as it could and hit a perimeter wall. If the wind was blowing in the other direction it could have been a lot worse.

If your plane crashed in ripe, dry wheat field and ignites no Co2 extinguisher is going to be much use at all.

Jason

johnls

Which club are you referring to.?

John

aussiesteve

Man that sux.
Our Home club in Oz also got extremely jealous when I introduced gas planes there. They invented a new rule about allowing gas engines only on low fire danger days because they were so paranoid. Fun part was - I asked the club to extend the rule to include the use of LiPos only on low fire danger days but because the club president likes to fly LiPo powered "gliders" that was never going to happen. The best bit is - They've since had a small fire there - Yep you guessed it - It was the LiPo powered glider that caused it.

Take my word on this one though. You are unlikely to win against the "Werthers sucking, Pipe smoking has beens" until time does it's thing and they are here no more. Unless it is a particularly good field to fly at, Do what we did - move to another club where the attitudes are more modern.

Here's the results of a survey that was performed on this exact topic

http://www.georgiajets.org/RMI_html_...Home_Page.html

Here's another thread that might help you

http://www.rcuniverse.com/forum/m_62...tm.htm#6266155

Here's one on LiPo fires

http://www.rcuniverse.com/forum/m_61...tm.htm#6111435

Jgwright

I have had my fair share of crashes over the years, and I am pleased to say that so far none have caught fire. Most of my models have been 44 powered. Usually the engine is sited behind the tank. The tanks are usually nice thick walled Dubro tanks and the engine so far has not ruptured the tank when crashing. I have also been lucky as the worst damage I have had is a damaged starter motor and bracket. The front of the airframe helps absorb the crash, protecting the engine. I have also seen models with large engines that have not fared so well. I asked Sara at Wren today if they have had a burned '44 engine back for repair and she said just one. There are hundreds of engines out there so this may be of help to you.

John

busbi

Hi all,
I could not let this subject go without defending the club in question. This club has one of the best sites in this part of the country, sites in this area are almost imposible to replace if lost. Our club is surrounded by large fields of crops, members are requested not to fly jets over the crops when they are ripe because of the risk of fire in the event of a crash, this is only a few days each year.
One of the two jet flyers, probably birdseed2, was asked not to fly whilst the crops were ripe this summer only to argue that the crops were not ripe, the farmer started harvesting THAT day!
I agree with aussiesteve who recommended that birdseed2 should join another club.

I don't smoke a pipe but have to confess to enjoying the odd Wherthers original.

busbi

brjensen71

My Feedback: (1)

I am not a turbine flyer, but I have started a corn field on fire. But I did it with a bad bearing on a combine ( harvest equipment for the non-agricultural types ). But the conditions need to be right, to be "ripe" all color is gone in the leaves and stalk, and it needs to be dry. In those cases once fire is started, and if there is any breeze, you may need a couple of fire departments to get the fire out. On the other hand, I have seen a combine start on fire in the field and burn to the ground, and never burn the field beyond the combine.

In my case, because of the breeze, the leave burned off and cleaned off the ground, but the fire went fast enough that the stalks were still upright with the ears attached. No insurance claim required.

I have also witnessed a turbine crash that started an alfalfa field on fire. It crashed directly on a cut windrow of drying hay, burn a 15' diameter area, but would have unlikely spread any further. I believe most of that burn area was due to spreading a vaporized fuel. It made a regular mushroom cloud when it hit.

With the exception of a turbine, a fire would more likely to be started by shorting a battery after a crash than by a hot engine, gas or glow. With the turbine, the extra hot engine combined with a very large fiber glass type fuel cell ( easy to crack or rupture compare to a typical gas or glow tank ) and a lot of speed cause the fuel to atomize in the air and ignite in contact with the extremely hot engine starting the fire. But even then, if the corn field has any color left in it, the fire would probably not spread.

Remember, in the fall even after the corn is harvested, the field could still start on fire, 95% of the fuel is still there, just chopped up and shreaded. so until it rains or field is tilled, the fire danger is still there.

A fire can happen, most of the time it is unlikely, but a little common sense goes a long way. If your having a drought and everything is tiner box dry, rubber powered FF might be the only safe bet.


Be nice to the farmer, often he is the one that returns lost models in the fall.

Wayne22

My Feedback: (2)

I have a video of a Grippen going in nose first into dry scrub grass.....nothing happend...not even a puff of smoke...

davo580

my club field here in west aussie is in a nation park {whiteman park} here if it is a extreme fire danger day the park rangers close us down untill it is less than a extreme fire danger day.. it is good here because we can fly 7 days a week 8 am till dusk...over the year due to rain or fire days we only loose about ten days of the year

alasdair

I have a couple of examples.
I crashed a jet in June, airframe completely shattered, but the fuel tank - a 2 litre cider bottle - remained intact and bounced clear of the crash site.
A couple of weeks ago a friend crashed a moulded ARF jet and again no chance of a fire as the moulded fuel tank remained intact, though a small amount of fuel dribbled out of the detached pipes.

I think that in dry weather you had better not overfly highly inflamable trees or crops - just in case - and the same goes for any petrol or lipo powered models.

CHAWKJIM

HI GUY

IS THERE A FUEL TANK THAT IS NOT GOING TO PUNCTURE? I MEAN IS THAT NOT WHAT MAKES THE FIRE ON A CRASH? IF YOUR TANK IS LIKE A RACE CAR TANK WITH A BLADDER OR SOMETHING YOU WOULD BE LESS LIKELY TO HAVE A FIRE. DOES ANYONE MAKE SOMETHING LIKE THAT? IF NOT MAYBE I SHOULD.

Synthetic

My Feedback: (18)

Cape Hobbys,
Your caps lock is on.

Kevlar is all I know of. I have not heard of any "bladder" type fuel cells but maybe someone else has.

Sounds like a good idea.

Harley Condra

My Feedback: (4)

Synthetic,
Years ago, bladder type fuel tanks were in common use.
Basically, they were a I.V. bag that was filled with fuel and bled of all remaining air. A set of them was supplied with my first engine. (RAM 750...1998.

They are mentioned in the AMA turbine regulations........no longer allowed, as they were easily ruptured in a crash.

Harley Condra
BVM REP
JetCat REP

bidrseed2

My Feedback: (2)

Busbi,

welcome to the forum.

I intentionally, did not mention which club i was referring too. That was not the purpose of the thread.

With regards to being asked not to fly during "ripe" crop time, i suspect you got your erroneous info from the individual who threatened to "look into not renewing membership" for those who dared to argue with his suggestions.I can provide you with that email, if you were not on the mailing list.

You stated that i tried to argue that the crops were not ripe, yet they were harvested that day.

I have re read the emails that were exchanged to ensure i had not suggested otherwise. I suspect you should question the reliability of your source. I never stated the crops were ripe or not, nor did i state any intention to fly.

It was suggested in the email that it may be several weeks before harvest occured. I am not a farmer, and i enquired, having not been at the field with the intention of flying my jet for several weeks, before the email exchange, as to how it was being determined that the current state of the crops, was prohibitive to jet flying.

If someone had an objective way of deciding, or knowing when the fire risk was higher, then that is what i was trying to ascertain. If it was purely subjective, and opinion, then how do we balance the concerns of an individual thinking mid may is too risky against another individual thinking early august is the right time.

Answers on a postcard.....

The purpose of starting this thread was to assess fire risk following turbine crashes, not to restart a "flaming" war similar to the large model debacle.

As to your comments regarding losing the site.

For the record, certain members expressed concerns over flying of large models at our site. Initially it was because, some members didnt like them. After it was pointed out that, that wasnt enough, they moved onto noise. After it was argued that most glow models wouldnt pass a BMFA noise level check, and any problem of this being ameliorated by the remote nature of our site, they moved on to site security. After that rallying call was made, it seemed irrelevant acutally HOW large models jeoporidised the site.
I suspect at some point later someone will cry that jets are risking the site, the actual mechanism of such will of course be irrelevant.

Synthetic

My Feedback: (18)

Harley,
Were the "bladders" inside of a fuel tank such as a Kevlar fuel tank or were they just "bladder" bags?
Thanks,
Don

rolsen12

I have in R/C since 1958 and I am presntly flying jets.
You can say that I have crashed my share, and I never have had afire.
That includes the giant gas powered planes of about ten years ago.
If you set your failsafe programs prior to flying ,then there is realy no danger of getting shot down in flames.
The gas and turbine powered aircraft are no more fire prone than the alcahol (glow) powered aircraft.
You hit the nail right on the head when you said jelious.
A good way to shut up the crybabies is to get a good fire extinguisher(co2) and have it with you at the field.
Sounds like the rest of your club would like to go back to 1952.

HarryC

My Feedback: (1)

Some of the crashes at the classic jets meetings have resulted in a fireball or small local fire after the crash. The field is grass, not ripe crops, so it isn't going to burn but I suspect that the flames would have been enough to set ripe dry crops on fire. I would never fly over ripe dry crops as I consider it to be a fire risk in the event of a turbine crash.

I wrote the jet rules at my club as I was the first, and still the only jet flier there. Anticipating resistance and a desire to ban jets from certain members, I pre-empted it by including a rule banning the flying of jet models while the fields immediately next to the runway have dry crops in them - meaning their colour has turned substantially brown. I interpret the rule "wot I wrote" and stop jet flying when they are predominantly brown with a merest hint of green still showing. Until harvest this means no jetting for perhaps 4- 6 weeks which allowing for bad British weather means I lose only a small number of weekends when I can't fly the jet.

I have pointed out at the club that petrol is far more combustible and explosive than jet fuel, that crashed lipos are a fire risk, but since certain sections of the membership use such materials they see nothing risky about it!

We waived the rule for one day this summer for our big scale event, by asking the farm manager his opinion of the risk of the crops burning if the jet crashed and burned, since it was shortly after the enormous floods we had and everything was still damp. He was happy the crops would not burn despite being brown, so we allowed jetting for that one day.

I am happy with the club ban on those few weeks - I would feel uncomfy, like knowing an accident is waiting to happen, if the club allowed unrestricted jet flying. We enjoy an excellent relationship with the farmer and estate owners, one burned field would destroy that and I doubt I would be welcome back at the club, if indeed it continued to exist if it lost the use of the airfield.

Harry

bidrseed2

My Feedback: (2)

II like brjensens statements about the colour going, the green leaving and it all being brown. That sounds like a useful rule, and less open to interpretation than the "ripe" criteria.

Interpretation, i suspect is the issue at my club.

But my concern, is that the state and colour could still be claimed to be subjective by certain members.
(Just as harry aludes to that they wouldnt see a problem with lipo powered ac flying during the same time period)

I expect you can see my concern about the integrity of a very small number of club members, given that a new poster appears on the forum, makes a comment that he would like me to join another club, but then doesnt feel able to reveal his name.

Harley Condra

My Feedback: (4)

Don,
The I.V. bags were the tanks...they were not encapsulated inside another type of tank or container....they laid inside the fuselage and collapsed as the fuel was depleted. The fuel pump suction would collapse them completely when the fuel was depleted.
Obviously, the only time they could have been any more dangerous than a hard tank was when they contained fuel. A sharp object could puncture them, and the fuel would leak out. In the event of a crash, they could rupture and some or all of the fuel would be released, and the hot engine or pipe would set the fuel off.
Their use that the fuselage structure did not contain any sharp edges or objects that could puncture them and cause leakage.I have seen a fuel leak (under pressure) start an in-flight fire that consumed enough of the the airplane to cause a loss of control before the pilot could get it back on the ground. Kevlar tanks were used in that particular airplane.

I don't exactly understand rolsen12's comments, as many turbine powered airplanes contain much more fuel than he has ever pumped into a gas powered airplane at one time. For example, a KingCat contains 168 oz. of fuel....that's more than 5 quarts! An Ultra Bandit contains almost 2 gallons! How much does the average gas powered 30% 3D thing contain? Nowhere near that amount, I'll bet.

A properly set failsafe program won't help if the airplane is "dumb thumbed" into the ground, or if an electrical power loss, etc., causes the crash. There are so many scenarios that can, have and will cause a crash, that no rule such as he describes will ever completely stop the fireball.
I'll put my flame suit on now.....

Harley Condra
BVM REP
JetCat REP