Pull water off your wings
10-22-2003, 10:53 AM
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Pull water off your wings
I wonder how hard it would be to make a device to to simulate pulling water off the wings like the real jets do when they pull high G's. Maybe just a simple valve that would open up under G force, to release water thats under pressure in a tank. Man that would just complete the whole package..High speed pass, pull to the vertical with mist coming off the wings OH YA..
Z
Z
10-23-2003, 09:09 AM
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RE: Pull water off your wings
Actually, the Firebird just leaks fuel out of poorly designed vents on hard pull-ups. So, that would be how to get your simulated vapor too.
10-23-2003, 11:51 AM
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RE: Pull water off your wings
Sorry John - You may debate it all you want,but the fuel isn't coming out the vent on a hard pull up. BVM rumor only
The vapor is originating at the wing tip and I've see it with binoculars when you move the ailerons when the wing is loaded up.
If it was fuel it would happen on all days not just humid ones.
Sure is hard to get fuel to run against positive air pressure (about 10-20 lbs)
I've seen this plane since its very first flight and hundreds since then.
Hey, It did it before Tom put the external vents on.
When your the only one that has a plane that can do it ,I guess everyone has to make excuses.
I hate rumors,just face it, It's COOL!
MO
The vapor is originating at the wing tip and I've see it with binoculars when you move the ailerons when the wing is loaded up.
If it was fuel it would happen on all days not just humid ones.
Sure is hard to get fuel to run against positive air pressure (about 10-20 lbs)
I've seen this plane since its very first flight and hundreds since then.
Hey, It did it before Tom put the external vents on.
When your the only one that has a plane that can do it ,I guess everyone has to make excuses.
I hate rumors,just face it, It's COOL!
MO
10-23-2003, 02:33 PM
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RE: Pull water off your wings
Sure is hard to get fuel to run against positive air pressure
Just my $.02 (in canadian funds...)
Kelly
10-23-2003, 04:51 PM
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RE: Pull water off your wings
ORIGINAL: Marty O
Sure is hard to get fuel to run against positive air pressure (about 10-20 lbs)
Sure is hard to get fuel to run against positive air pressure (about 10-20 lbs)
Assuming a perfectly designed pitot vent, if you are getting 10 psi into the tank as you indicate, then the Firebird is indeed quite a plane, as it needs to be doing 1100ft/sec or about 750 mph to get that kind of dynamic pressure from a pitot. As it is, if the Firebird is doing a relistic but quick 300 mph, the dynamic pressure available in reality would be about 1.5 psi. I'd like to see the pressure measurements where you get your figures from.[>:]
Now, that's assuming you have a well functioning pitot system. However, the pitot vents I've seen on the Firebird are located much too close to the leading edge, and are smoothly faired - like a bullet, which will contribute to the opening easily being subject to suction forces when the wing is at an increased angle of attack. A much better place for the pitot is either on a long boom- like a test airplane, or spaced away from the lower wing skin like many GA airplanes, using the wing itself to keep airflow straight into the tube. And you don't want any fairing around the tube to change the local direction of the air. As designed, the firebird vent does not encourage flow straight into the tube when the airplane is at an angle of attack. Leading-edge suction is a known phenomena which I refered to here, last time I was in a discussion like this:
http://www.rcuniverse.com/forum/m_73.../tm.htm#734222
Not only will you find further expanation from me there, but also admission by a firebird owner that it is indeed fuel venting. Could it still be possible to be seeing actual vapor formation, sure. However, there is no physical reason why fuel would not be sucked out of these vents either. Plus, the pump effect mentioned by kelly would be just miniscule, and not show any effect in such a short time. And with an actual owner of one of these planes saying it's fuel - I can easily take that explanation.
BTW - if there was someone around here to spread a "BVM" rumor, it sure wouldn't be me.
10-23-2003, 10:27 PM
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RE: Pull water off your wings
The phenomenon looks great on Tom’s Firebird whether it is a “poorly designed vents†or not.
BTW, Did you guys know that Tom’s new kit won best sports at Superman this year?
Congratulations Tom.
Regards
Ben
BTW, Did you guys know that Tom’s new kit won best sports at Superman this year?
Congratulations Tom.
Regards
Ben
ORIGINAL: Johng
Actually, the Firebird just leaks fuel out of poorly designed vents on hard pull-ups. So, that would be how to get your simulated vapor too.
Actually, the Firebird just leaks fuel out of poorly designed vents on hard pull-ups. So, that would be how to get your simulated vapor too.
10-23-2003, 11:00 PM
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RE: Pull water off your wings
Sure is hard to get fuel to run against positive air pressure (about 10-20 lbs)
10-24-2003, 09:36 AM
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RE: Pull water off your wings
I get vapor trails on my Roo wing tips on very humid days on a hard turning type manouver.
I've only seen it a couple times, and it was almost ready to rain at the time.
A navy pilot friend of mine was amazed to see a model do it.
I've only seen it a couple times, and it was almost ready to rain at the time.
A navy pilot friend of mine was amazed to see a model do it.
10-25-2003, 01:16 AM
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RE: Pull water off your wings
OK yup, I was probably splitting hairs with the pump comment. Now that I read your explanation it could make sense when the vent is exposed to a sudden impulse in the opposite direction to flow, provided there was some liquid fuel in the line from a previous impulse.. The pump would only serve to clear the line in a near steady state condition.
As for vapor trails, I don't think any one of us can definitively state which side wins this one. I don't know if Tom's fuel system would allow for it in the Firebird, but someone should try installing a check valve to allow flow in only, with a ball valve in parallel to allow air flow out for fueling. The aircraft could theoretically be flown with the ball valve open or closed to simulate both scenarios. If the vapor trails exist in one scenario, but not in the other (in roughly the same atmospheric conditions), I suppose we would have a clearer understanding of the situation.
Personally, I hope someone tries it and gets some pretty serious vapor with the on-way valve functioning...
I know its an entirely different situation, but I've flown a jet that sprung a fire hose leak of kerosene in flight. The fuel was invisible until landing, where it was gushing out of every orifice and the only indicator was the lack in top en power as the leak got worse and worse.
Either way, the JMP Firebird is one fine jet.[8D]
Kelly
As for vapor trails, I don't think any one of us can definitively state which side wins this one. I don't know if Tom's fuel system would allow for it in the Firebird, but someone should try installing a check valve to allow flow in only, with a ball valve in parallel to allow air flow out for fueling. The aircraft could theoretically be flown with the ball valve open or closed to simulate both scenarios. If the vapor trails exist in one scenario, but not in the other (in roughly the same atmospheric conditions), I suppose we would have a clearer understanding of the situation.
Personally, I hope someone tries it and gets some pretty serious vapor with the on-way valve functioning...
I know its an entirely different situation, but I've flown a jet that sprung a fire hose leak of kerosene in flight. The fuel was invisible until landing, where it was gushing out of every orifice and the only indicator was the lack in top en power as the leak got worse and worse.
Either way, the JMP Firebird is one fine jet.[8D]
Kelly
10-25-2003, 07:57 AM
#15
RE: Pull water off your wings
I agree that the pitots on the Firebird do experience negative pressure at times during a flight. The thing that does not make sense to me, is that unless the pitots were plumbed with clunks into the tanks, why would they both produce a solid enough flow to cause the very visible trails? Would not the fuel all be at the back of the tanks in a pull to vertical? Also, it appears that this vapor trail can happen at any time during the flight, which means it is not effected by fuel load.
We've all found fuel residue around our fuel vents. But only the Firebird has a visible trail. There are still too many questions to be answered, for me to be convinced. If I could just win the Lotto, I would buy one and find out.
We've all found fuel residue around our fuel vents. But only the Firebird has a visible trail. There are still too many questions to be answered, for me to be convinced. If I could just win the Lotto, I would buy one and find out.
10-25-2003, 11:09 AM
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RE: Pull water off your wings
[sm=confused.gif]Vapor trails depend on the relative humidity in the air + the sudden depression suffered by the air stream over the minimum press zone over the wing or inside the vortex generated in a wing tip.
[sm=drowning.gif]To make vapor trails, we must increase the airspeed &/or the "G's" to increase the lift force and consecuently the depression in the air that make posible to reach the dew point of the air.
Maybe we can get the required air depression using a specific shape or device that accelerate the air or generates a vortex similar to the one that occurs in the big jets in the wing tips or in the flaps tips.
[&:] Also we can try to lower the temperature in the airflow over the wing, maybe with the sudden discharge of a bottle containing gas under pressure guided through a tube over the wing.
[:@] Finally we can get the vapor trails for sure increasing the airspeed to higher levels, of course in humid conditions.
I think that now there are just a few model jets (military UAV) able to fly at such airspeeds to produce vapor trails. Sometimes the vapor trials are the result of a deep imagination of some spectators or pilots.
[:-]I don't think a fuel leakage in the fuel vent can produce such a vapor trail, if we think that the fuel leak is very small and unusual, almost imposible in a normal flight condition.
[sm=drowning.gif]To make vapor trails, we must increase the airspeed &/or the "G's" to increase the lift force and consecuently the depression in the air that make posible to reach the dew point of the air.
Maybe we can get the required air depression using a specific shape or device that accelerate the air or generates a vortex similar to the one that occurs in the big jets in the wing tips or in the flaps tips.[&:] Also we can try to lower the temperature in the airflow over the wing, maybe with the sudden discharge of a bottle containing gas under pressure guided through a tube over the wing.
[:@] Finally we can get the vapor trails for sure increasing the airspeed to higher levels, of course in humid conditions.
I think that now there are just a few model jets (military UAV) able to fly at such airspeeds to produce vapor trails. Sometimes the vapor trials are the result of a deep imagination of some spectators or pilots.[:-]I don't think a fuel leakage in the fuel vent can produce such a vapor trail, if we think that the fuel leak is very small and unusual, almost imposible in a normal flight condition.
10-26-2003, 09:05 AM
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RE: Pull water off your wings
There is no question that the Firebird leaks fuel from the front of the
Wings...
But if it is producing H2O vapor trails, there is a simple explanation for it..
That Plane has a somewhat high wing loading and I think is more prone
to creating lower pressures.
Eddie Weeks
Wings...
But if it is producing H2O vapor trails, there is a simple explanation for it..
That Plane has a somewhat high wing loading and I think is more prone
to creating lower pressures.
Eddie Weeks
05-15-2008, 09:57 PM
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RE: Pull water off your wings
Explain why a heavy ballasted sloper has left vapor trails off the tips it was flying around 140mph nowhere near 300mph, north face Palos Verdes Ca
05-16-2008, 04:14 AM
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RE: Pull water off your wings
I can't believe that this was dug up from 5 years ago! [X(]
I would like to know though, how you watch a model jet with binoculars so accutely to the point of being able to see the ailerons deflection during high g manouvres and see anything. Ever seen a video taken with a camcorder zoomed in close to the model while flying? Zoomed in that close you can hardly keep up with it and keep it in the viewfinder, and they are saying they can actually see vapor off of the ailerons when they deflect????? Sorry don't buy that.
Post a video and I'll eat my words apologetically; till then, yeah right!
Les
I would like to know though, how you watch a model jet with binoculars so accutely to the point of being able to see the ailerons deflection during high g manouvres and see anything. Ever seen a video taken with a camcorder zoomed in close to the model while flying? Zoomed in that close you can hardly keep up with it and keep it in the viewfinder, and they are saying they can actually see vapor off of the ailerons when they deflect????? Sorry don't buy that.
Post a video and I'll eat my words apologetically; till then, yeah right!
Les
05-16-2008, 08:59 AM
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RE: Pull water off your wings
I wonder how hard it would be to make a device to to simulate pulling water off the wings like the real jets do when they pull high G's
05-16-2008, 10:29 AM
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RE: Pull water off your wings
But the plans for a vapor trail mechanism is ready,
I just need the winter season to experiment and construct it..
- just like my afterburner effect!!
Tor
I just need the winter season to experiment and construct it..
- just like my afterburner effect!!
Tor
05-16-2008, 10:54 AM
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RE: Pull water off your wings
ORIGINAL: Johng
Sorry chief, but those "pitots" are poorly designed to be able to guarantee positive pressure into the tank.
Assuming a perfectly designed pitot vent, if you are getting 10 psi into the tank as you indicate, then the Firebird is indeed quite a plane, as it needs to be doing 1100ft/sec or about 750 mph to get that kind of dynamic pressure from a pitot. As it is, if the Firebird is doing a relistic but quick 300 mph, the dynamic pressure available in reality would be about 1.5 psi. I'd like to see the pressure measurements where you get your figures from.[>:]
Now, that's assuming you have a well functioning pitot system. However, the pitot vents I've seen on the Firebird are located much too close to the leading edge, and are smoothly faired - like a bullet, which will contribute to the opening easily being subject to suction forces when the wing is at an increased angle of attack. A much better place for the pitot is either on a long boom- like a test airplane, or spaced away from the lower wing skin like many GA airplanes, using the wing itself to keep airflow straight into the tube. And you don't want any fairing around the tube to change the local direction of the air. As designed, the firebird vent does not encourage flow straight into the tube when the airplane is at an angle of attack. Leading-edge suction is a known phenomena which I refered to here, last time I was in a discussion like this:
http://www.rcuniverse.com/forum/m_73.../tm.htm#734222
Not only will you find further expanation from me there, but also admission by a firebird owner that it is indeed fuel venting. Could it still be possible to be seeing actual vapor formation, sure. However, there is no physical reason why fuel would not be sucked out of these vents either. Plus, the pump effect mentioned by kelly would be just miniscule, and not show any effect in such a short time. And with an actual owner of one of these planes saying it's fuel - I can easily take that explanation.
BTW - if there was someone around here to spread a "BVM" rumor, it sure wouldn't be me.
ORIGINAL: Marty O
Sure is hard to get fuel to run against positive air pressure (about 10-20 lbs)
Sure is hard to get fuel to run against positive air pressure (about 10-20 lbs)
Assuming a perfectly designed pitot vent, if you are getting 10 psi into the tank as you indicate, then the Firebird is indeed quite a plane, as it needs to be doing 1100ft/sec or about 750 mph to get that kind of dynamic pressure from a pitot. As it is, if the Firebird is doing a relistic but quick 300 mph, the dynamic pressure available in reality would be about 1.5 psi. I'd like to see the pressure measurements where you get your figures from.[>:]
Now, that's assuming you have a well functioning pitot system. However, the pitot vents I've seen on the Firebird are located much too close to the leading edge, and are smoothly faired - like a bullet, which will contribute to the opening easily being subject to suction forces when the wing is at an increased angle of attack. A much better place for the pitot is either on a long boom- like a test airplane, or spaced away from the lower wing skin like many GA airplanes, using the wing itself to keep airflow straight into the tube. And you don't want any fairing around the tube to change the local direction of the air. As designed, the firebird vent does not encourage flow straight into the tube when the airplane is at an angle of attack. Leading-edge suction is a known phenomena which I refered to here, last time I was in a discussion like this:
http://www.rcuniverse.com/forum/m_73.../tm.htm#734222
Not only will you find further expanation from me there, but also admission by a firebird owner that it is indeed fuel venting. Could it still be possible to be seeing actual vapor formation, sure. However, there is no physical reason why fuel would not be sucked out of these vents either. Plus, the pump effect mentioned by kelly would be just miniscule, and not show any effect in such a short time. And with an actual owner of one of these planes saying it's fuel - I can easily take that explanation.
BTW - if there was someone around here to spread a "BVM" rumor, it sure wouldn't be me.
Above mentions the need for the Firebird to fly at around 750 mph to accomplish this.
I have seen a few of them fly and that was about how fast they were going!
Don
