The workings of an Engineered Air Trap, Diffuser and Self Bleeding Filter
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The workings of an Engineered Air Trap, Diffuser and Self Bleeding Filter
This is a short video made by Intairco and shown on the Final Modellbau stand at Jet Power 2016 showing just what you can get away with a well engineered solution.
https://www.youtube.com/watch?v=zI-xuGCEbk4
https://www.youtube.com/watch?v=zI-xuGCEbk4
#3
Totally convincing so my Intairco trap and filter go into my SkyGate Hawk, Olympus powered, (complete with the super Intairco gear and door valve unit) this winter (it's a pig of a job to get to the engine on this aircraft so no easy job) . Shame it will not be visible because the units are so beautifully made, wouldn't be out of place on a RR Trent !
Should convince the doubters about Festo fittings, too.
Sorry I missed you guys at Jet Power.
David.
Should convince the doubters about Festo fittings, too.
Sorry I missed you guys at Jet Power.
David.
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Yeah David. We had our eyes open for you but heard you could not make it. Can tell you that there is something huge coming out of the Intairco Fuel sytem camp in the next 4 weeks or so when we finish flight testing.
Shane
Shane
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It is all about the size of the bubble. Large bubbles that enter the fuel pump compress halting the fuel flow to the engine. Large bubbles entering the engine can knock out the flame front. The demonstration clearly shows that if the air is broken up into smaller packets then the interuption is minor. We are by no means suggesting that you should fly with a low level in your air trap on the contrary any air in your trap could mean that you have a fuel pickup issue. However if you practice extreme aerobatics or you do suffer an inflight air leak into your fuel system then a well engineered design will help to keep the engine running and give you a better chance of a safe landing.
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It is all about the size of the bubble. Large bubbles that enter the fuel pump compress halting the fuel flow to the engine. Large bubbles entering the engine can knock out the flame front. The demonstration clearly shows that if the air is broken up into smaller packets then the interuption is minor. We are by no means suggesting that you should fly with a low level in your air trap on the contrary any air in your trap could mean that you have a fuel pickup issue. However if you practice extreme aerobatics or you do suffer an inflight air leak into your fuel system then a well engineered design will help to keep the engine running and give you a better chance of a safe landing.
Nicely engineered unit and interesting video.
All you need to do now is make the pick up flexible to reach all the fuel and insert it into a normal tank and do away with the air trap altogether as i have done since I started in jets 20 years ago.
I have only found it necessary to add a small hopper tank in my latest plane because the tank is u shaped and the pick up in the main tank does not always go where it should when inverted. There would have been no problem if the tank had been made as 2 separate tanks or with a divider in it.
John
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This is a short video made by Intairco and shown on the Final Modellbau stand at Jet Power 2016 showing just what you can get away with a well engineered solution.
https://www.youtube.com/watch?v=zI-xuGCEbk4
https://www.youtube.com/watch?v=zI-xuGCEbk4
very impressive!
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Bart
Nicely engineered unit and interesting video.
All you need to do now is make the pick up flexible to reach all the fuel and insert it into a normal tank and do away with the air trap altogether as i have done since I started in jets 20 years ago.
I have only found it necessary to add a small hopper tank in my latest plane because the tank is u shaped and the pick up in the main tank does not always go where it should when inverted. There would have been no problem if the tank had been made as 2 separate tanks or with a divider in it.
John
Nicely engineered unit and interesting video.
All you need to do now is make the pick up flexible to reach all the fuel and insert it into a normal tank and do away with the air trap altogether as i have done since I started in jets 20 years ago.
I have only found it necessary to add a small hopper tank in my latest plane because the tank is u shaped and the pick up in the main tank does not always go where it should when inverted. There would have been no problem if the tank had been made as 2 separate tanks or with a divider in it.
John
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I can attest to the above described findings. Between Peter Ayache and myself, my 1/4 scale MB-339 has 25 flights. Zero problems, running a Behotec SB-220. Since this was my first experience with the Intairco system, I ran extensive tests, similar to the prior videos. No evidence of cavitation and amazing resistance to shutdown from air in the large airtrap and the small filter in line.
The super clear cylinder makes it easy to see even the smallest contaminants.
The super clear cylinder makes it easy to see even the smallest contaminants.
Last edited by Tom Antlfinger; 10-02-2016 at 08:39 AM.
#13
My god, Tom, You are using Festo fittings and Tygon. According to some here on RCU they can't possibly work and must be avoided ! You must be very lucky! ( or just know what you are doing !)
Perhaps one day I will describe the unique but simple and very cheap dual air trap system I have used for 17 Seasons in my BVM F4, zero flameouts , essential for a model which gas the gliding characterstics of a cast iron manhole cover.
David.
Perhaps one day I will describe the unique but simple and very cheap dual air trap system I have used for 17 Seasons in my BVM F4, zero flameouts , essential for a model which gas the gliding characterstics of a cast iron manhole cover.
David.
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You are right David. I never mix Tygon with Festo Female sockets. My first photo obscured the fill fitting. It is a nipple with a 6 mm clip, not a Festo fitting. I like to run my fill lines well out of the fuse with flexible Tygon rather than PE tubing.
Cheers....TA
Cheers....TA
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" essential for a model which has the gliding characterstics of a cast iron manhole cover"
Actually my BVM F-4 floats like an ASW-15 glider when compared to my BVM F-100/AMT Pegasus, out of gas with Flaps and Gear Down, Slats Out, Speedbrake Deployed, with Draggy Wing Tanks hanging in the Slipstream. Still cleaning the shorts after that brain fart.
Actually my BVM F-4 floats like an ASW-15 glider when compared to my BVM F-100/AMT Pegasus, out of gas with Flaps and Gear Down, Slats Out, Speedbrake Deployed, with Draggy Wing Tanks hanging in the Slipstream. Still cleaning the shorts after that brain fart.
Last edited by Tom Antlfinger; 10-02-2016 at 04:27 PM.
#16
Do the same video at something over 60,000 on the turbine. I'm sorry it shows what we already know, that at constant rpm and low power modern turbines will cope with a bubble. Vary the throttle or ask for full power and then see what happens...
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Dave. If you look at the video the turbine rpm was up to 75 k. It was set at that speed as it showed max air draw for that level in the air trap. I struggle to think you believe that this extreme display is normal, i know your a lot smarter than that. I guess if you feel your prefered trap performs better then i would be keen to see it.
#18
You can't replicate flight situations on the ground easily, but a held power setting is very rare!
I still have not worked out why people needed to re invent the wheel (Other than really rare big turbine models which require a completely different approach anyway)
I do think my preferred choice is the best...that's why I use and sell it. If I had any doubt I'd not be risking hours of work and thousands of pounds in flight!
With the right fuel tank installation a container with a tube in the middle will work as there will be no air supplied to the trap, people seem to look at the various huge capacity bubble traps as a Elastoplast for poor tank engineering-its not.
Constantly supplied with fuel this and other traps will work 100% as long as it does not develop air leaks from the multiple joints.
I still have not worked out why people needed to re invent the wheel (Other than really rare big turbine models which require a completely different approach anyway)
I do think my preferred choice is the best...that's why I use and sell it. If I had any doubt I'd not be risking hours of work and thousands of pounds in flight!
With the right fuel tank installation a container with a tube in the middle will work as there will be no air supplied to the trap, people seem to look at the various huge capacity bubble traps as a Elastoplast for poor tank engineering-its not.
Constantly supplied with fuel this and other traps will work 100% as long as it does not develop air leaks from the multiple joints.
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Thanks Dave but i still think you maybe missing the point, i am not saying that this is how the trap should work, only what would happen in an extreme circumstance. The ONLY reason i see for an air trap is to highlight a developing problem such as a suction air leak. This would show up as a bubble in the trap that is now alot easier to see. In extreme circumstances of air in the trap then it is highly unlikely to cause a flameout if a diffusser is fitted. Even better if this diffusser is custom built to limit pressure drop.
#20
Originally Posted by Tom Antlfinger;1226356d9
You are right David. I never mix Tygon with Festo Female sockets. My first photo obscured the fill fitting. It is a nipple with a 6 mm clip, not a Festo fitting. I like to run my fill lines well out of the fuse with flexible Tygon rather than PE tubing.
Cheers....TA
Cheers....TA
Really, I must stick to just one glass of red after a good days flying ( my SkyGate Hawk) which uses lots of Tygon and several Festo fittings Both in suction and pressure !
David.
#21
Thanks Dave but i still think you maybe missing the point, i am not saying that this is how the trap should work, only what would happen in an extreme circumstance. The ONLY reason i see for an air trap is to highlight a developing problem such as a suction air leak. This would show up as a bubble in the trap that is now alot easier to see. In extreme circumstances of air in the trap then it is highly unlikely to cause a flameout if a diffusser is fitted. Even better if this diffusser is custom built to limit pressure drop.
I thought we had by now established through the countless threads that a perfect fuel pickup is impossible to achieve in every flight condition and the function of a header tank is to provide some buffer for these moments when air gets inevitably sucked in without letting it get to the engine.
Pleated paper filters allow the header tank to do this a while longer for the same volume of fuel because they do not let air through while they are partially submerged.
The intairco filter looks interesting though because I've had friends flameout because of a bubble of air stuck in their filter. Transparency allows quicker inspection without removal and is only available on the festo filter which is reportedly unreliable.
So these two seem like good reasons to install a filter but I still dont see any but the bling for the header tank.