Engine bay fire detection with video camera

[Eric Greenwell[_4_]]

I don't trust the heat sensor on the right side of the engine bay to activate soon
enough to land safely, especially for fires caused by the bearings of the lower
propeller belt drive. It'd be easy to install a small video camera at the front of
the engine bay, and run the wires to a small display in the cockpit where it's
easily seen. This could be used on gas power and FES (for the battery compartment)
gliders. Has anyone tried this?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Kenn Sebesta]

On Saturday, October 10, 2020 at 12:54:55 PM UTC-4, Eric Greenwell wrote:
> I don't trust the heat sensor on the right side of the engine bay to activate soon
> enough to land safely, especially for fires caused by the bearings of the lower
> propeller belt drive. It'd be easy to install a small video camera at the front of
> the engine bay, and run the wires to a small display in the cockpit where it's
> easily seen. This could be used on gas power and FES (for the battery compartment)
> gliders. Has anyone tried this?
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> - "A Guide to Self-Launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1

That's an intriguing idea. How would you monitor the video feed? Would it be part of your active scan during takeoff?

You might do better with a FIR camera than an EO one. I'm just guessing here, but it's probably easier to do background subtraction to highlight heat changes than to see smoke in a very well-ventilated compartment.

[Eric Greenwell[_4_]]

Kenn Sebesta wrote on 10/10/2020 12:09 PM:
> On Saturday, October 10, 2020 at 12:54:55 PM UTC-4, Eric Greenwell wrote:
>> I don't trust the heat sensor on the right side of the engine bay to activate soon
>> enough to land safely, especially for fires caused by the bearings of the lower
>> propeller belt drive. It'd be easy to install a small video camera at the front of
>> the engine bay, and run the wires to a small display in the cockpit where it's
>> easily seen. This could be used on gas power and FES (for the battery compartment)
>> gliders. Has anyone tried this?
>>
>> --
>> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
>> - "A Guide to Self-Launching Sailplane Operation"
>> https://sites.google.com/site/motorgliders/publications/download-the-guide-1
>
> That's an intriguing idea. How would you monitor the video feed? Would it be part of your active scan during takeoff?
>
> You might do better with a FIR camera than an EO one. I'm just guessing here, but it's probably easier to do background subtraction to highlight heat changes than to see smoke in a very well-ventilated compartment.
>
I think glancing at it just before you start the takeoff roll, then again after
you reach a safe height (300 feet, say) and every 20-30 seconds after that would
be adequate. But - I think you are right that detecting the smoke or flame might
be very difficult in the engine bay, which is my problem (The FES pilots might
have success in the battery compartment, though). Probably need to do some smoke
tests on the ground and inflight with the engine running.

I have a FLIR ONE for my iPhone, but mounting it in the engine bay with a
Lightning cable to the front isn't practical, since it can't be turned on remotely.

I couldn't find a cheap camera (<$200) online that could be used the way I'd like
to, either.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[George Haeh]

How about a battery powered home smoke detector?

[Eric Greenwell[_4_]]

George Haeh wrote on 10/10/2020 2:46 PM:
> How about a battery powered home smoke detector?
>
I don't know how it would respond to the high temperatures in the engine bay during normal
operation (ambient temperature in summer + engine heat), or the effect of air turbulence on the
detector, so I suspect it'd take a lot more testing than I'm interested in doing.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[[email protected]]

On Saturday, October 10, 2020 at 4:21:34 PM UTC-4, Eric Greenwell wrote:
> Kenn Sebesta wrote on 10/10/2020 12:09 PM:
> > On Saturday, October 10, 2020 at 12:54:55 PM UTC-4, Eric Greenwell wrote:
> >> I don't trust the heat sensor on the right side of the engine bay to activate soon
> >> enough to land safely, especially for fires caused by the bearings of the lower
> >> propeller belt drive. It'd be easy to install a small video camera at the front of
> >> the engine bay, and run the wires to a small display in the cockpit where it's
> >> easily seen. This could be used on gas power and FES (for the battery compartment)
> >> gliders. Has anyone tried this?
> >>
> >> --
> >> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> >> - "A Guide to Self-Launching Sailplane Operation"
> >> https://sites.google.com/site/motorgliders/publications/download-the-guide-1
> >
> > That's an intriguing idea. How would you monitor the video feed? Would it be part of your active scan during takeoff?
> >
> > You might do better with a FIR camera than an EO one. I'm just guessing here, but it's probably easier to do background subtraction to highlight heat changes than to see smoke in a very well-ventilated compartment.
> >
> I think glancing at it just before you start the takeoff roll, then again after
> you reach a safe height (300 feet, say) and every 20-30 seconds after that would
> be adequate. But - I think you are right that detecting the smoke or flame might
> be very difficult in the engine bay, which is my problem (The FES pilots might
> have success in the battery compartment, though). Probably need to do some smoke
> tests on the ground and inflight with the engine running.
>
> I have a FLIR ONE for my iPhone, but mounting it in the engine bay with a
> Lightning cable to the front isn't practical, since it can't be turned on remotely.
>
> I couldn't find a cheap camera (<$200) online that could be used the way I'd like
> to, either.
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> - "A Guide to Self-Launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1

Possibly a camera and display like used for rear view in RV's might be adaptable.
FWIW
UH

[jfitch]

Eric, the search terms "ir flame sensor" typed into Amazon or Google yields hundreds of results, starting at less than $5. They seem to have a broad angle of detection, a typical claim is sensing the flame from a cigarette lighter at 80 or 100 cm. Seems like it might be worth a try. I think a detector with an alarm is going to be more useful than having to scan a video during an already busy time.

Here for example, are 10 of them for $12 - a lifetime supply!

https://www.amazon.com/LGDehome-Infrared-Detection-Detecting-Distance/dp/B07TV1CZDK/ref=sr_1_1?dchild=1&keywords=ir+flame+sensor&qid=1602372059&s=electronics&sr=1-1


On Saturday, October 10, 2020 at 9:54:55 AM UTC-7, Eric Greenwell wrote:
> I don't trust the heat sensor on the right side of the engine bay to activate soon
> enough to land safely, especially for fires caused by the bearings of the lower
> propeller belt drive. It'd be easy to install a small video camera at the front of
> the engine bay, and run the wires to a small display in the cockpit where it's
> easily seen. This could be used on gas power and FES (for the battery compartment)
> gliders. Has anyone tried this?
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> - "A Guide to Self-Launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Dave Nadler]

On Saturday, October 10, 2020 at 12:54:55 PM UTC-4, Eric Greenwell wrote:
> I don't trust the heat sensor on the right side of the engine bay...

Nor should you, it didn't go off in at least one fire I discussed in Feb.

> It'd be easy to install a small video camera at the front of the engine bay...

More likely to let you know somethings wrong.
Paul Mander had this setup in his ASH-25J, but obviously it wasn't enough.

An inerting system is a great idea, except the airflow through the engine bay...

I don't know if there's a really good solution.

Fires are bad.

[kinsell]

I believe those things are intended for indoor operation, where the
ambient light isn't strong. Outside, with the engine bay doors open,
you're likely to be getting lots of false alarms.


On 10/10/20 5:26 PM, jfitch wrote:
> Eric, the search terms "ir flame sensor" typed into Amazon or Google yields hundreds of results, starting at less than $5. They seem to have a broad angle of detection, a typical claim is sensing the flame from a cigarette lighter at 80 or 100 cm. Seems like it might be worth a try. I think a detector with an alarm is going to be more useful than having to scan a video during an already busy time.
>
> Here for example, are 10 of them for $12 - a lifetime supply!
>
> https://www.amazon.com/LGDehome-Infrared-Detection-Detecting-Distance/dp/B07TV1CZDK/ref=sr_1_1?dchild=1&keywords=ir+flame+sensor&qid=1602372059&s=electronics&sr=1-1
>
>
> On Saturday, October 10, 2020 at 9:54:55 AM UTC-7, Eric Greenwell wrote:
>> I don't trust the heat sensor on the right side of the engine bay to activate soon
>> enough to land safely, especially for fires caused by the bearings of the lower
>> propeller belt drive. It'd be easy to install a small video camera at the front of
>> the engine bay, and run the wires to a small display in the cockpit where it's
>> easily seen. This could be used on gas power and FES (for the battery compartment)
>> gliders. Has anyone tried this?
>>
>> --
>> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
>> - "A Guide to Self-Launching Sailplane Operation"
>> https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Ian Molesworth]

You can buy a car reversing camera that will run off a USB-to-go connector on just about any modern phone.

Install the cable ( usual 4mm USB size ) into the engine box to the cockpit. Perhaps low down and angled up. Plug in to your phone. If it's right you could even see the engine erect so leave it out if there's something wrong.

Some even have an LED light to illuminate a dark engine compartment.

[Kenn Sebesta]

> I think glancing at it just before you start the takeoff roll, then again after
> you reach a safe height (300 feet, say) and every 20-30 seconds after that would
> be adequate. But - I think you are right that detecting the smoke or flame might
> be very difficult in the engine bay, which is my problem (The FES pilots might
> have success in the battery compartment, though). Probably need to do some smoke
> tests on the ground and inflight with the engine running.
>
> I have a FLIR ONE for my iPhone, but mounting it in the engine bay with a
> Lightning cable to the front isn't practical, since it can't be turned on remotely.
>
> I couldn't find a cheap camera (<$200) online that could be used the way I'd like
> to, either.

Depending on how many resources you want to throw at this, the MLX90640 is reportedly a decent 24x32 FIR camera which interfaces over I2C. So you could stream data to a microcontroller, or even an embedded computer such as a Raspberry Pi (although please use an industrial spec variant) and then forward that data to the cockpit. I'd do a static background subtraction so that you're only looking at heat blooms. One of the nice things about this approach is you can have the screen be completely dark except for anomalies. Much easier to set up automated warnings in this case.

A camera can only see what it's pointed at, so if the ignition risk is hidden from view a single camera might not be useful. How that affects things I can't say. However, you might be able to set up strategically positioned mirrors so as to see many sides of the engine bay. Since you don't really care if the image is distorted, it won't bother you.

Testing is probably straightforward, since you could rig up a power resistor glow red-hot while in the air, so you could see what kind of response you actually get when everything is shaking and heating up.

In terms of hardware, this R&D effort will likely cost <$200, including the screen. In terms of time, it's probably pretty straightforward as well, especially if you're comfortable with hacking together various scripts from blogs and stackoverflow.

Before I jumped on the camera train, though, I'd give careful consideration to what it means to detect a fire. You might find that the kind of fires you want to detect are far earlier than would be seen by a camera. I don't have a firm concept of fire detection (What does it mean to detect a fire? How do we even define "fire" in this context?) so I'm at a loss for what are the precursors to a fire.Â*

[Martin Gregorie[_6_]]

On Sun, 11 Oct 2020 07:18:06 -0700, Kenn Sebesta wrote:

> Before I jumped on the camera train, though, I'd give careful
> consideration to what it means to detect a fire. You might find that the
> kind of fires you want to detect are far earlier than would be seen by a
> camera. I don't have a firm concept of fire detection (What does it mean
> to detect a fire? How do we even define "fire" in this context?) so I'm
> at a loss for what are the precursors to a fire.
>
Good point: I know of a Duo that was burnt out on the ground. The fire
source was a binding wheel brake that, while the glider was being towed
out, ignited dry grass in the wheel box. This in turn melted plastic
(factory fitted AFAIK) fuel tubes running alongside the wheelbox to the
fuel cock in the cockpit, The wheelbox fire damaged the fuel tubes enough
to let fuel escape and burn.

I didn't see this: just the glider-shaped black patch on the airfield.
The fire spread fast enough that the owners were lucky to get the car
unhooked and away from the glider before it burnt as well.

I'm not saying that this particular ignition event could occur in the
air, just that a turbo or SLMG may well have potential ignition points
outside the engine compartment.


--
Martin | martin at
Gregorie | gregorie dot org