Some info on fuel tank boost pumps in the CT-133 Silver Star to detail the challenges in providing positive fuel pressure to the engine driven fuel pump on the venerable Nene 10. There are multiple interconnected fuel tanks in the wings featuring electrically driven boost pumps. Tip tanks use air pressure from the engine to transport fuel to the system. All feed into the fuselage tank behind the cockpit. The fuse tank has an electrically driven double ended centrifugal pump to supply positive pressure to the engine driven fuel pump. The reason it is double ended is to ensure positive fuel pressure under negative G conditions such as when the aircraft is flown upside down or during other aerobatic manoeuvres resulting in negative G. Not something the average airliner typically contends with.
In cars with port fuel injection, yes, the pump in the tank is the only fuel pump. In Direct Injected cars, typically the pump in the tank is just the low pressure "lift pump" (aka: boost pump), which feeds the High Pressure Fuel Pump in the engine bay. On most more modern DI engines, the HPFP is driven off one of the overhead camshafts, most often the exhaust camshaft. Some engines drive the HPFP off of the timing chain.
"Aw, she's a beauty!" ... "I'm not a big fan of football" ... I'm the same, played some team sports as a kid and quickly decided that I'd rather spend my saturdays upgrading the bearings/bushes in my skateboard trucks or maintaining my bike. Sport was just getting up early to run around with a bunch of other kids and then coming home again, the bike and the skateboard meant freedom for the whole weekend. :) Haven't dropped in to the channel for a while and I'm instantly reminded why I subscribed, haha. Lots of content to catch up on, cheers mate
You are not alone..... I was amazed by your commentary during the video you aired tonight during the Super Bowl time slot. With the exception of the number of wheels involved, you could have written my hobby biography. I've always enjoyed the family and friend bonding while watching championship sports but to be honest I've always been drawn closer to watching NHRA drag racing, Formula 1 and recently to a lesser degree Cup stockcar racing. I've raised a family which has produced some very avid professional football, NHL Hockey and Major League Baseball fans and I'm glad my lack of passion for their interests didn't drive them towards resentment. Don't get me wrong - I love to watch my granddaughters and grandsons in their school and travel league sports. However I just don't feel 'connected' watching professional or college athletes. I identify vicariously watching skilled drivers and mechanics ply their skills Finally your description of boost fuel pumps and how they supplement the delivery of a fluid to a jet engine was excellent. My RUclips subscriptions already include all the channels you suggested and I agree they offer more facts than the pundits. Please count me as a devoted Agent Jay Z channel fan. Thanks for all you do.
Automotive fuel pumps are like a not positive displacement pumps but if you dead head one, they will usually stop turning. Most of them produce between 9 and 60 psi pressure depending on the system. There are some that have extremely different specifications with high pressure and rpm. Most of them are returnless and the pump is controled by a fuel pump module that can change the rpm of the pump depending on demand. Some pumps are 3 phase alternating current where the module produces that at a variable frequency to control output. On direct injection cars, the in tank pump feeds a high pressure positive displacement pump that is run from the cam shaft. When the high pressure pump fails, engine oil is contaminated with gas just like the old days. Those fuel pumps you are describing here are similar to the variable displacement A/C compressor on many cars.
Wasn't allowed to have That Poster as I was too young. Haven't watched a Super Bowl in 55 years, but did have an XB70 (and an F-15, 16, 86, 4 with removable J79) hanging from the ceiling at different points. Along with a prized Tamiya Lotus JPS 72D. Here in the U.S., this makes me very strange to the point of possibly being on a list or 2. Naturally I became a professional musician. Greg's Airplanes has deep dives into technically arcane topics, also by an airliner pilot, and Ron Rodgers is another off the beaten path airline pilot channel.
Awesome stuff as always professor Jay. I’m an industrial water chiller mechanic. I’m guessing where as a positive displacement pump is like a screw compressor or scroll type compressor. The centrifugal chillers the impeller works off of the lift of the lift ratio of the low pressure side and high pressure side. Those get out of whack and we get compressor stall followed by surge. Surge is bad news
I've been engineering and tweaking my fuel control design over the past year. I'm in a good spot now, but I can't tell you how much time I've spent contemplating different fueling approaches. Different pump designs, fuel pressure and flow rate relationships at different pump RPMs, regulation, recirculation or dead heading, proportional throttle valves for flow control at constant pressures, variable speed pump throttle control with no regulator. It made my head spin...
Tank boost pumps (the non +ve displacement type) also allow fuel to be drawn through the pump by the engine driven pump in the case of boost pump failure. That ensures that the tank's fuel remains useable even if the boost pump has failed
yep, when it comes to explaining "incidents", Blanco Lirio, a.k.a. Juan Brown, is my favorite! I also enjoy Ward Carrol, especially in regards to naval aviation. I've also been enjoying a small channel called "Diesel Thunder". Most of it deals with working on the Collings Foundation's F-4 Phantom, and a fair amount is about working on the electrical systems. As a former A-4 Skyhawk avionics guy, it does draw me in. Of course, when I'm wanting to learn about the details of jet engines, there's only one source! .... Agent Jay Zed/Zee/etc.
Centrifugal compressors are simpler and cheaper to make, they are tougher and more resistant to stall. They lose efficiency after about the size needed for about a 1000 Hp engine, and they are limited in the ultimate discharge pressure they can achieve. Some exceptions at the upper end of capacity are the PT6B at almost 2000 Hp, and the PW150 at around 5,000Hp. Axial compressors are capable of much higher mass flow rate, and are able to achieve compressor ratios of up to 50:1. They are more complex, more expensive, and require more maintenance, but in the 5,000Hp to 500,000 Hp range, they work really well.
@@AgentJayZ thanks for the answer, I researched a bit and learned that they also have a relatively low rpm limit and you can't really stage them. Always great to hear different sources.
The rpm limit is determined by diameter, exactly as with axials. The limit of the number of stages is usually about 2 for centrifugals, whereas 15 or more is no difficulty with axials.
in cars it depends. in port injection (most common rn?) cars the fuel tank pump is indeed the only fuel pump, but it does something in the range of 50-ish psi. direct injected engines have a further high pressure pump that is lobe driven off the camshaft usually.
The electric fuel pump in a car running on gasoline with a carburetor or port injection supplies fuel that is not pumped again before being used by the engine. But on a diesel or gasoline direct injection car, there is another fuel pump which is mechanically engine driven that supplies fuel to the injectors. This is broadly similar to the engine driven pump on a jet engine. The injectors on older diesels were basically fancy check valves, so the injection pump had to precisely meter the fuel. But modern diesels and GDI engines have electronic injectors that are computer controlled to meter the fuel.
I'm a subscriber of all the channels you named. Juan Brown (Blancolirio) is also an A&P mechanic. I have a question prompted by your discussion of boost pumps. It may be a bit outside of your wheelhouse but I'll ask anyway. The CL 13 Saber, among other fighters often perform numerous acrobatic maneuvers during flight, including flying inverted. How does the aircraft maintain fuel flow from partially filled tanks without interruption during these maneuver? It seems that jet fuel, being liquid, will shift around in the tank during flight with the potential of an air pocket being positioned at the fuel intake? Clearly this isn't a problem for passenger or freight aircraft. Thanks for considering this question.
I don't have access to data on the aircraft fuel system in the Sabre. It's important to watch the maneuver being performed, because inverted flight does not necessarily mean negative G. I believe the Sabre has a maximum negative G endurance of 20 seconds, mainly because the oil is only scavenged out of the bearing sumps in positive G. A swinging pickup in the oil reservoir ensures the oil supply is maintained while flying in negative G, but no oil gets returned, so the supply runs out quick. Since the engine can run inverted at all, I think there is a swinging fuel pickup at least in the main tank, into which the other tanks drain to keep it full. Negative G is avoided, but would be experienced in steady, level inverted flight. Things like barrel rolls and inside loops are positive G, all the way through.
The newer cars are direct injected so they have an electric fuel pump in the tank and a mechanical fuel pump on the engine that raises it to around 1200 PSI so it could be called a boost pump
A bit late to the party, but for reference: the fuel pump system in the C604 is rather elaborate. During engine start, the electric boost pumps provide inlet pressure to the engine-driven pumps. But once running, the engine-driven pumps, besides providing pressure for the fuel nozzles, also create a so-called "motive flow" for the venturi-type "ejector pumps" in the collector tanks, which supply the engine-driven pump inlet pressure in normal operation. So the engine pump, in a way, creates its own inlet pressure, and the electric boost pumps can be turned off. Beautiful system. Only if these ejector pumps fail, the electric boost pumps take over the ejector pumps' jobs. In addition, the main ejector pumps in turn create motive flow for the scavenge pumps, which are also venturi-type, whose job it is to scavenge the fuel from main tanks into the collector tanks. I don't operate these jets myself, but I have analysed numerous accidents and I know how to read manuals. In non-aerobatic aircraft, fuel pickups are usually fixed at the lowest point when the aircraft is straight and level. They always leave a bit of fuel in the tanks, aptly referred to as "unusable fuel", which is the amount that cannot be pumped out in the most adverse "normal "attitudes (especially critical during acceleration and climb).
Fuel boost pumps in an airliner are necessary to ensure a constant supply of fuel to the engine driven pumps at high altitude. The engine driven pumps will not be able to rely upon the static air pressure at high altitude to provide enough differential pressure between the fuel tank and the engine driven pumps to ensure uninterrupted flow - so boost pumps located in the fuel tanks are necessary. Fuel pumps don't "suck" fuel from the tanks; in the absence of a boost pump submerged in the fuel, they rely on atmospheric pressure to do the work. Atmospheric pressure at FL180 (18000 ft.) is roughly one half that at sea level and it becomes proportionally less as altitude increases. In the B727, 757 and 767's I flew for 33 years, the fuel boost pumps were required to be "on" at all times from engine start to shutdown. In the event of a boost pump failure at altitude, we were required to descend to below FL260 (in the B727) to ensure sufficient fuel flow to the engine driven pumps due to atmospheric pressure alone.
Yes. Sorry about using the word suck. It's an easy mistake, even though I try not to make it. In one of the recent Patreon vids, we go through the fuel pressure switch. It's basically there to illuminate a cockpit light indicating boost pump failure. The engine can run without boost pumps, but it's happier if it doesn't have to.
Additionally, the fuel boost pumps in the B727 and B767 were used to "dump" fuel when necessary. None of those aircraft had the ability to transfer fuel from one tank to another in flight so there were no "transfer pumps". The fuel systems were designed so that we could "cross-feed" fuel from any fuel tank to any engine when necessary for balance considerations but we typically ran "tank to engine" as the normal procedure.
Bombardier uses ejector pumps as their main boost pumps with a gear type motor driven pump as backup. Fuel is tapped from the engine driven pump to pressurize the ejector pump supply. The motor driven pump is used at startup and a backup to the ejector pumps.
"The engine driven pumps will not be able to rely upon the static air pressure at high altitude to provide enough differential pressure between the fuel tank and the engine driven pumps..." WTF? since virtually all fuel system components live at the same altitude and air pressure there is no altitude induced pressure differential. The only differential pressure that might exist is due to a difference in height between a pump and the tank from which it draws fuel. That is called "net positive suction pressure head, and yes, suction is a real engineering term used in pumping and fluid flow design. The boost pump is used to assure a positive pressure at the pump inlet. Please consider the fact that all the engines on a 727 are several feet higher than the top of any fuel tank so that should be a clear indication that atmospheric pressure is irrelevant. Another point, the tank mounted boost pumps are centrifugal pumps which like all in that family create a low pressure area at the impeller inlet while rotating, that phenomenon is is why the engineering term for that area is called the pump suction, it is the same if that pump is operated in space or at the bottom of the Marianas Trench.
Sorry for the confusion - I assumed that it was obvious that the differential pressure of which I spoke was the difference between "pump suction" (your term) and atmospheric pressure. I did not say that there was differential pressure solely due to atmospheric pressure. My point was that a fuel pump creates low pressure at it's inlet as it attempts to "draw" fuel from the tanks but then (in the absence of "boost pumps") relies on atmospheric pressure to provide the "push" to move fuel from the tank towards the pump. The most "suction" any pump can produce is 0 psi and, at sea level, atmospheric pressure is close to 14.7 psi - never a problem having enough differential pressure for fuel to flow reliably for fuel systems on the ground. At "jet" cruising altitudes however, atmospheric pressure is much lower; hence the "differential pressure" force available to "push" fuel toward the pump is lower as well.. An extreme example - a fuel pump at 0 psi inlet pressure attempting to draw fuel from a tank (at the same height) that is also at 0 psi will not be able to do so without an "in-tank boost pump" to supply the required differential pressure. There must be a difference in pressure for any flow to occur - that's how pumps work. While it's true that aircraft with engines mounted lower than the fuel tanks can usually, but not always (depending on aircraft attitude), rely on "gravity" to supply some pressure to feed the fuel pumps, even the B757 and B767 aircraft (under wing mounted engines) with which I'm familiar normally require that the in-tank fuel boost pumps be operated continuously from before start to shut down. I'm not saying the engines won't run without the boost pumps on, but the aircraft is not "legal" for dispatch if all the boost pumps in a tank are inoperative. Additionally, if even one (of several) boost pumps in a given tank are inoperative, we're required to carry huge amounts of additional "penalty" fuel in that tank to ensure the remaining boost pumps are never "un-ported". As for the "space or at the bottom of the Marianas Trench" statement - it's true that "pump suction" is the same, 0 psi in both places but the "outside" pressure is vastly different. The pressure in the depths of the Marianas Trench are in the thousands of psi, lots of differential pressure between the "outside" pressure and "pump suction". In contrast, the pressure outside a space vehicle is essentially 0 psi - the same as the "pump suction" (no differential pressure to do the "work" and therefore no fuel flow). Having been employed as a space systems engineer some years ago, my recollection is that to solve this problem, spacecraft fuel system tanks are pressurized with helium or some other inert gas. That gas pressure then provides the required differential pressure for fuel to flow (also, since they live in 0 gravity, there are additional problems related to keeping the fuel at the "pickup" location so that the pumps get only fuel, not the pressurizing gas...).
11:00 like a non centrifugal auto AC compressor, nice info. Regarding sports, i enjoy moto tt on Isle of Man, will be in 2 months or so. Btw, show us again your bike, maybe a story or 2, regardind maintanace. Tkanks for all your work explaning us all this.👍
If I started a series about motorcycles, would you help out? I need questions, that I and a guest would answer based on our experiences in riding, racing, building and breaking. Jet City Moto?
I had a couple tours working on the good old CT-133 Silver Star. Rolls Royce Nene 10 in our Canadair license-built versions, more power than the original Lockheed birds. Anyhow, boost pumps. The fuselage tank behind the cockpit in the T-33 featured a double ended boost pump. Double ended because fighter jocks in training & regular pilots flying them liked to go inverted and/or pull negative G occasionally. Although the fuselage tank is kept full being fed by tip tanks & wing tanks, when those are empty the level in the fuselage tank will drop & if the aircraft is subjected to negative G a single ended pump would cavitate. The wing tanks had single ended booster pumps to move fuel to the fuselage tank, but the tip tanks were pressurised with air to transfer fuel.
@@AgentJayZ Ah lucky you, I'll have to find that vid. On my tour in Baden during the Cold War I worked mostly on the T-BIrd, just a 6 month stint line servicing on the 104. I had the pleasure of many back seat trips in the T-Bird. Never lucked in for a 104 ride though.
3:00 I couldn’t care less for sports either.. and I also had WW2 planes hanging from the ceiling in my room! That’s not so weird… Watching a bunch of 20 to 30 year olds in tights run around and chase a ball.. now that’s weird!
On the D.G. Probable Cause channel from cockpit audio the Challenger pilot didnt ask for Prist when it took on fuel, causing it to gel in the tanks and eventual fuel starvation.
@@AgentJayZYou spoke about the Challenger fuel system and the plane fueling up before it took off. I wouldn't have added pertinent information if you hadn't brought it up first.
OK, I was not trying to figure out why the crash happened. I was only trying to explain what boost pumps were. Because Juan mentioned them without saying much else about what they were.
Hello... Why is it possible for something to malfunction in a car's engine and it stops in the street even though it is new or has been given proper maintenance, but this cannot happen in airplanes where the engines stop suddenly (except rarely)? Is the difference in the nature of the design and maintenance of the parts or in the level of maintenance? Hareth / Iraq
I've had an ignition coil fail on a new vehicle, stopping it in the street. Once running, a jet no longer needs its ignition system. But, yes. Design differences. Jets and piston engines are different in almost every way possible.
@@AgentJayZ -- Well, I "conveniently" forgot to mention that most of the time car engines are at a glorified idle. But I've going up some long "20 minute" grades at times. An aircraft engin operates at 50 to 75% most of the time.
I must live under a rock, not sure what the one thing is, but loved the video. In new cars with direct injection the pump in the fuel tank is a low pressure fuel pump (lpfp) and it feeds another pump that is usually mechanically driven called the high pressure fuel pump (hpfp)....so the lpfp is kinda like a boost pump =) Anyways, good stuff!
8:12 I have to say I've never heard anyone saying gas turbines don't use a lot of fuel. Maybe they're referring to thermal efficiency vs. other engines; more energy output per kg of fuel.
Something small, like a T58, a RR Viper, a Garrett TPE 331, or an Allison 250 C-18. You need to be able to fond the overhaul manual, and a source of parts. Donor engines will save you hundreds of thousands. The used market in the aviation world is still extremely expensive, so you will need to become a detective to find the stuff you need. Check out Darren Duncan's channel where he did an amazing job on his surplus Fairchild J44. The OH manual, and the illustrated parts catalog are an absolute must. Look for those first at places like eflightmanuals.com. If you are an extremely talented technician, and have "all the tools", and think you can figure it out on your own, I wish you luck, but failure and financial loss is a certainty in my opinion. You have been advised by someone who does this for a living.
@@AgentJayZ thanks for the very informative reply! I have a home machine shop and im an engineering student so im more prepared than most. Im not gonna do this to make money, just for fun and to learn how the technology works.
I have a Question, What is the importance of setting a N1 power setting for takeoff and climb i get mixed answers on this some people say as long as you don't exceed ITT or max limits on N1 N2 your fine but in the books there are power setting for takeoff and climb are those just for calculations or hard numbers thank you very much
Don't know what engine you are talking about. With a turbofan engine, thrust is mostly proportional to N1, which is the speed of the LP compressor, which is also fan speed. If you are looking to run the engine at max... right to the ragged edge, then EGT, and the speed limits of both shafts are your "redline". But as I understand it, each flight of each aircraft type, with each type of engine has a calculated optimal power setting. If you underpower, you might not make it. If you overpower, you are wasting fuel and causing more than necessary stress and wear on the engines.
Interesting also that in the small engine world ( I do mostly lawn care- the twin cylinder small engines, up to 1,000cc ) and the lil vacuum fuel pump supplies about the same...3-5 PSI but at a higher volume the engine can use. Any more and it'll blow past the needle and seat in the carb. The fuel injected engines can use the same pump, but that feeds into a high pressure module, the output is right at 39 PSI to feed the injectors. The module is electric, and controlled by the ECU.
So in diesels that have direct injection 50% of the fuel returns to the tank to keep the injectors cool...do jet engines use fuel recirculation to keep the injection system cool?
No. There is a return from the fuel control output to the pump inlet. Fuel flow is high, and generally fuel temp is about room temp, so the fuel control has no specialized cooling ability.
Not all diesel engines return large quantities of fuel or use it for injector cooling. Practically all have a return line to collect leak off fuel (all plunger pumps leak) and return it to the system but that might only amount to an occasional drip. It all depends on the engine design. Turbine engine aircraft often use fuel as an oil coolant so heat is added, not removed. "Room temperature" for an airliner cruising at high altitude may be 60 or 70 degrees below zero and wing tanks rapidly cool in the airflow. Take a look at the bottom (sometimes top) of the wings of an aircraft that has just arrived at the gate after a transcontinental flight and you will almost certainly see frost in the shape of the remaining fuel level. This doesn't apply to SR-71s of course, they had exactly the opposite issue.
Are fuel boost pumps left on once the engine is running I think that fuel supply units are very clever even on older engines no matter what the throttle selection is
It all depends on the airframe manufacturer and becomes part of the Pilot's Operating Handbook or aircraft operations manual. Some say that auxiliary or boost pumps must be on for takeoff and landing then selected off at some point, some are selected on before takeoff and turn off automatically so they remain in a standby condition unless fuel pressure to the engine driven pump decreases. There are any number of combinations and procedures, all of which are dictated by the airframe manufacturer as part of the certification process.
Well, right now, I'm at Heathrow waiting for my flight to Singapore,on a British Airways B.787 with Trent 1000s. BA, please bring back the A380s on this route. The 787 is a noisy little thing, compared to the 380, and the 777s, even those with Trents weren't much better.
Also, yep generally in port fuel injected cars, you're exactly right, the fuel pump in the tank is the only pump. On cars with direct injection (diesels and newer gasoline cars) there's a second high pressure pump mechanically driven off the enine to provide the >1000 psi required for the injectors
So the offensive team (the ones that start with the ball) has 4 attempts to gain Ten yards distance towards their goal line. Normally when they talk about gameplay you’ll hear the number of down which the offensive team is playing, and the distance they have yet to traverse before they can restart the count of “downs”. Now it can be a number greater than ten if the player with the ball runs away from the starting line as well IE “1st and 15”. I only played football because my friend did, otherwise could not care less about the sport.
I subscribe to all YT creators you mention in this video. Wierd coincidence or proof that just pure relevat content pays off? Maybe wrong english but you get the point…
When I describe fuel pumps as gear driven, I mean they are attached to the engine, and driven from a gearbox literally attached to the main shaft of the engine via a radial drive shaft. Boost pumps are in the fuel tanks, and electrically driven. They are nowhere near the engine.
Greeting. I love watching your shows. I have one request / question. Why don't you at least enable automatic translations. Automatic translations from English work well now, so you can understand everything you're talking about. It's not my place to get angry, but you're not a TV presenter to have your voice mixed perfectly. However, while you are speaking, the machines are buzzing, you are turning... and then people who do not speak English as their first language have problems. I would beg you to just open the automatic translation option. You don't have to write your speech in English. The program translates from your pronunciation
I will look into it again, but so far the automatic subtitles are garbage. So inaccurate that they are not useful, and just annoy me. A lot of what I do is to straighten out misunderstandings about how these machines work. The subtitles only add to that misunderstanding. Why would I think audio translations are any better?
Some info on fuel tank boost pumps in the CT-133 Silver Star to detail the challenges in providing positive fuel pressure to the engine driven fuel pump on the venerable Nene 10. There are multiple interconnected fuel tanks in the wings featuring electrically driven boost pumps. Tip tanks use air pressure from the engine to transport fuel to the system. All feed into the fuselage tank behind the cockpit. The fuse tank has an electrically driven double ended centrifugal pump to supply positive pressure to the engine driven fuel pump. The reason it is double ended is to ensure positive fuel pressure under negative G conditions such as when the aircraft is flown upside down or during other aerobatic manoeuvres resulting in negative G. Not something the average airliner typically contends with.
Agent J - Z, I'm always amazed at how sport heads talk about sport like it really matters.
In cars with port fuel injection, yes, the pump in the tank is the only fuel pump. In Direct Injected cars, typically the pump in the tank is just the low pressure "lift pump" (aka: boost pump), which feeds the High Pressure Fuel Pump in the engine bay. On most more modern DI engines, the HPFP is driven off one of the overhead camshafts, most often the exhaust camshaft. Some engines drive the HPFP off of the timing chain.
"Aw, she's a beauty!" ... "I'm not a big fan of football" ...
I'm the same, played some team sports as a kid and quickly decided that I'd rather spend my saturdays upgrading the bearings/bushes in my skateboard trucks or maintaining my bike. Sport was just getting up early to run around with a bunch of other kids and then coming home again, the bike and the skateboard meant freedom for the whole weekend. :)
Haven't dropped in to the channel for a while and I'm instantly reminded why I subscribed, haha. Lots of content to catch up on, cheers mate
You are not alone..... I was amazed by your commentary during the video you aired tonight during the Super Bowl time slot. With the exception of the number of wheels involved, you could have written my hobby biography. I've always enjoyed the family and friend bonding while watching championship sports but to be honest I've always been drawn closer to watching NHRA drag racing, Formula 1 and recently to a lesser degree Cup stockcar racing. I've raised a family which has produced some very avid professional football, NHL Hockey and Major League Baseball fans and I'm glad my lack of passion for their interests didn't drive them towards resentment. Don't get me wrong - I love to watch my granddaughters and grandsons in their school and travel league sports. However I just don't feel 'connected' watching professional or college athletes. I identify vicariously watching skilled drivers and mechanics ply their skills Finally your description of boost fuel pumps and how they supplement the delivery of a fluid to a jet engine was excellent. My RUclips subscriptions already include all the channels you suggested and I agree they offer more facts than the pundits. Please count me as a devoted Agent Jay Z channel fan. Thanks for all you do.
Blancolirio was the channel that pointed me to AgentJayZ when he was talking about compressor stalls. Still subscribed to both channels ;)
Also subscribed to Mentor Pilot, Mentor Now, 74 Gear, Flight Chops, VAS Aviation, Trent Palmer and Experimental Aircraft
Automotive fuel pumps are like a not positive displacement pumps but if you dead head one, they will usually stop turning. Most of them produce between 9 and 60 psi pressure depending on the system. There are some that have extremely different specifications with high pressure and rpm. Most of them are returnless and the pump is controled by a fuel pump module that can change the rpm of the pump depending on demand. Some pumps are 3 phase alternating current where the module produces that at a variable frequency to control output. On direct injection cars, the in tank pump feeds a high pressure positive displacement pump that is run from the cam shaft. When the high pressure pump fails, engine oil is contaminated with gas just like the old days. Those fuel pumps you are describing here are similar to the variable displacement A/C compressor on many cars.
Wasn't allowed to have That Poster as I was too young. Haven't watched a Super Bowl in 55 years, but did have an XB70 (and an F-15, 16, 86, 4 with removable J79) hanging from the ceiling at different points. Along with a prized Tamiya Lotus JPS 72D. Here in the U.S., this makes me very strange to the point of possibly being on a list or 2. Naturally I became a professional musician.
Greg's Airplanes has deep dives into technically arcane topics, also by an airliner pilot, and Ron Rodgers is another off the beaten path airline pilot channel.
Awesome stuff as always professor Jay. I’m an industrial water chiller mechanic. I’m guessing where as a positive displacement pump is like a screw compressor or scroll type compressor. The centrifugal chillers the impeller works off of the lift of the lift ratio of the low pressure side and high pressure side. Those get out of whack and we get compressor stall followed by surge. Surge is bad news
Thanks, I was always wondering about boost pumps. Seriously.
Yeah Blonco ! Love that man's and your knowledge and work. Thanks for sharing with us Peons
I've been engineering and tweaking my fuel control design over the past year. I'm in a good spot now, but I can't tell you how much time I've spent contemplating different fueling approaches. Different pump designs, fuel pressure and flow rate relationships at different pump RPMs, regulation, recirculation or dead heading, proportional throttle valves for flow control at constant pressures, variable speed pump throttle control with no regulator. It made my head spin...
I remember once wacking off to a giant poster of the F-104
Some courage there!
I made a hybrid poster with Heather Thomas piloting an F4 Phantom 2!
Sorry but I don't kiss and tell...
🤣🤣🤣
Jay-z must be your "go to" to "get er done" then
Tank boost pumps (the non +ve displacement type) also allow fuel to be drawn through the pump by the engine driven pump in the case of boost pump failure. That ensures that the tank's fuel remains useable even if the boost pump has failed
True
Juan Browne is bhaddass, but my "airhead" brothers agree that you are an integral part of the general knowledge of aeronautics.
Thanks!
You know, I rode an airhead to Oshkosh in 2023.
BMW R1200 G/S.
@@AgentJayZ ... got me
yep, when it comes to explaining "incidents", Blanco Lirio, a.k.a. Juan Brown, is my favorite! I also enjoy Ward Carrol, especially in regards to naval aviation. I've also been enjoying a small channel called "Diesel Thunder". Most of it deals with working on the Collings Foundation's F-4 Phantom, and a fair amount is about working on the electrical systems. As a former A-4 Skyhawk avionics guy, it does draw me in. Of course, when I'm wanting to learn about the details of jet engines, there's only one source! .... Agent Jay Zed/Zee/etc.
LOL hanging models and watching motorcycle racing was my jam back in the day too!
Q: what advantages does a axial compressor over a radial flux compressor have to justify the size difference?
Centrifugal compressors are simpler and cheaper to make, they are tougher and more resistant to stall. They lose efficiency after about the size needed for about a 1000 Hp engine, and they are limited in the ultimate discharge pressure they can achieve.
Some exceptions at the upper end of capacity are the PT6B at almost 2000 Hp, and the PW150 at around 5,000Hp.
Axial compressors are capable of much higher mass flow rate, and are able to achieve compressor ratios of up to 50:1. They are more complex, more expensive, and require more maintenance, but in the 5,000Hp to 500,000 Hp range, they work really well.
@@AgentJayZ thanks for the answer, I researched a bit and learned that they also have a relatively low rpm limit and you can't really stage them. Always great to hear different sources.
The rpm limit is determined by diameter, exactly as with axials.
The limit of the number of stages is usually about 2 for centrifugals, whereas 15 or more is no difficulty with axials.
@@AgentJayZ We/I have a solutions to the centrifugal/radial machine conundrum but it's unpatented as yet. ヅ
I provided the correct answer on your '...F-35B Lift Fan Drive Question...' page. The answer is simple. The engine is not oversized because the VTOL phase power requirement is obviously not greater than the power required for forward flight which has a drag component that is not present during the VTOL phase.
When I researched the lift fan system some years back, a dog clutch was mentioned in the drivetrain engagement. I don't know if that was an authoritative source so can't vouch for the veracity. With language being imprecise, that could probably mean a one way clutch, sometimes called an overspeed clutch, where metal rollers are located between two concentric rolling elements [somewhat resembling a roller bearing] that wedge themselves between these elements to act as one for power transfer/transmission. I suspect that the clutch requires frequent replacement due to the large forces present. We have patented a torque dense [i.e. compact], infinitely variable [for gradual power transfer], high speed & torque, hydrodynamic transmission/coupler [torque converter] that would significantly reduce this frequent servicing. We have also patented a simple, infinitely variable, torque dense, positive engagement, transmission which does not utilize involute/spur gears. It is called 𝔽𝕣𝕚𝕔𝕥𝕚𝕠𝕟𝕃𝕖𝕤𝕤 𝔾𝕖𝕒𝕣 © transmission and is based on our reformulation of gearing theory. In e-VTOLs the use of either allows significantly smaller motors and batteries for same performance/application. Similar benefits are derived in turbo-engine apps with smaller, lower cost, more efficient engines along with other features & benefits.
FYI, in the near future, we will bring out tech which enables antigravity with propulsion apps including interstellar travel, rendering all else but museum pieces/dinosaurs.
If anyone can hook me up with SpaceX or any of Musk's companies, Pratt & Whitney, etc. to improve many of their offerings, we'd each benefit greatly. ヅ
BTW, I'm a triple engineer, CE, ME, AE with penchant for nanotech, quantum biology, quantum physics, astrophysics and cosmology, among other things. ヅ
PS. Excellent channel. TnX.
Cheers
✈✈✈ 𝕄𝕀𝕃𝔸ℕ✈✈✈
in cars it depends. in port injection (most common rn?) cars the fuel tank pump is indeed the only fuel pump, but it does something in the range of 50-ish psi. direct injected engines have a further high pressure pump that is lobe driven off the camshaft usually.
Need to check out Ron Rodgers. Prior USAF test pilot went on to the air lines and retired. Interesting stories...
The electric fuel pump in a car running on gasoline with a carburetor or port injection supplies fuel that is not pumped again before being used by the engine. But on a diesel or gasoline direct injection car, there is another fuel pump which is mechanically engine driven that supplies fuel to the injectors. This is broadly similar to the engine driven pump on a jet engine. The injectors on older diesels were basically fancy check valves, so the injection pump had to precisely meter the fuel. But modern diesels and GDI engines have electronic injectors that are computer controlled to meter the fuel.
I'm a subscriber of all the channels you named. Juan Brown (Blancolirio) is also an A&P mechanic.
I have a question prompted by your discussion of boost pumps. It may be a bit outside of your wheelhouse but I'll ask anyway. The CL 13 Saber, among other fighters often perform numerous acrobatic maneuvers during flight, including flying inverted. How does the aircraft maintain fuel flow from partially filled tanks without interruption during these maneuver? It seems that jet fuel, being liquid, will shift around in the tank during flight with the potential of an air pocket being positioned at the fuel intake? Clearly this isn't a problem for passenger or freight aircraft. Thanks for considering this question.
I don't have access to data on the aircraft fuel system in the Sabre. It's important to watch the maneuver being performed, because inverted flight does not necessarily mean negative G.
I believe the Sabre has a maximum negative G endurance of 20 seconds, mainly because the oil is only scavenged out of the bearing sumps in positive G. A swinging pickup in the oil reservoir ensures the oil supply is maintained while flying in negative G, but no oil gets returned, so the supply runs out quick.
Since the engine can run inverted at all, I think there is a swinging fuel pickup at least in the main tank, into which the other tanks drain to keep it full.
Negative G is avoided, but would be experienced in steady, level inverted flight.
Things like barrel rolls and inside loops are positive G, all the way through.
@@AgentJayZ - Thank you.
The newer cars are direct injected so they have an electric fuel pump in the tank and a mechanical fuel pump on the engine that raises it to around 1200 PSI so it could be called a boost pump
A bit late to the party, but for reference: the fuel pump system in the C604 is rather elaborate. During engine start, the electric boost pumps provide inlet pressure to the engine-driven pumps. But once running, the engine-driven pumps, besides providing pressure for the fuel nozzles, also create a so-called "motive flow" for the venturi-type "ejector pumps" in the collector tanks, which supply the engine-driven pump inlet pressure in normal operation. So the engine pump, in a way, creates its own inlet pressure, and the electric boost pumps can be turned off. Beautiful system. Only if these ejector pumps fail, the electric boost pumps take over the ejector pumps' jobs. In addition, the main ejector pumps in turn create motive flow for the scavenge pumps, which are also venturi-type, whose job it is to scavenge the fuel from main tanks into the collector tanks. I don't operate these jets myself, but I have analysed numerous accidents and I know how to read manuals.
In non-aerobatic aircraft, fuel pickups are usually fixed at the lowest point when the aircraft is straight and level. They always leave a bit of fuel in the tanks, aptly referred to as "unusable fuel", which is the amount that cannot be pumped out in the most adverse "normal "attitudes (especially critical during acceleration and climb).
Dan Gryder - "Probable Cause " is also a great source of aviation information
Hi there, would you pls list some of channel you followed and enjoy, I would like to see them because I learn lots of things in your video. Thanks
Fuel boost pumps in an airliner are necessary to ensure a constant supply of fuel to the engine driven pumps at high altitude. The engine driven pumps will not be able to rely upon the static air pressure at high altitude to provide enough differential pressure between the fuel tank and the engine driven pumps to ensure uninterrupted flow - so boost pumps located in the fuel tanks are necessary. Fuel pumps don't "suck" fuel from the tanks; in the absence of a boost pump submerged in the fuel, they rely on atmospheric pressure to do the work. Atmospheric pressure at FL180 (18000 ft.) is roughly one half that at sea level and it becomes proportionally less as altitude increases. In the B727, 757 and 767's I flew for 33 years, the fuel boost pumps were required to be "on" at all times from engine start to shutdown. In the event of a boost pump failure at altitude, we were required to descend to below FL260 (in the B727) to ensure sufficient fuel flow to the engine driven pumps due to atmospheric pressure alone.
Yes. Sorry about using the word suck. It's an easy mistake, even though I try not to make it. In one of the recent Patreon vids, we go through the fuel pressure switch. It's basically there to illuminate a cockpit light indicating boost pump failure. The engine can run without boost pumps, but it's happier if it doesn't have to.
Additionally, the fuel boost pumps in the B727 and B767 were used to "dump" fuel when necessary. None of those aircraft had the ability to transfer fuel from one tank to another in flight so there were no "transfer pumps". The fuel systems were designed so that we could "cross-feed" fuel from any fuel tank to any engine when necessary for balance considerations but we typically ran "tank to engine" as the normal procedure.
Bombardier uses ejector pumps as their main boost pumps with a gear type motor driven pump as backup. Fuel is tapped from the engine driven pump to pressurize the ejector pump supply. The motor driven pump is used at startup and a backup to the ejector pumps.
"The engine driven pumps will not be able to rely upon the static air pressure at high altitude to provide enough differential pressure between the fuel tank and the engine driven pumps..." WTF? since virtually all fuel system components live at the same altitude and air pressure there is no altitude induced pressure differential. The only differential pressure that might exist is due to a difference in height between a pump and the tank from which it draws fuel. That is called "net positive suction pressure head, and yes, suction is a real engineering term used in pumping and fluid flow design. The boost pump is used to assure a positive pressure at the pump inlet. Please consider the fact that all the engines on a 727 are several feet higher than the top of any fuel tank so that should be a clear indication that atmospheric pressure is irrelevant. Another point, the tank mounted boost pumps are centrifugal pumps which like all in that family create a low pressure area at the impeller inlet while rotating, that phenomenon is is why the engineering term for that area is called the pump suction, it is the same if that pump is operated in space or at the bottom of the Marianas Trench.
Sorry for the confusion - I assumed that it was obvious that the differential pressure of which I spoke was the difference between "pump suction" (your term) and atmospheric pressure. I did not say that there was differential pressure solely due to atmospheric pressure. My point was that a fuel pump creates low pressure at it's inlet as it attempts to "draw" fuel from the tanks but then (in the absence of "boost pumps") relies on atmospheric pressure to provide the "push" to move fuel from the tank towards the pump. The most "suction" any pump can produce is 0 psi and, at sea level, atmospheric pressure is close to 14.7 psi - never a problem having enough differential pressure for fuel to flow reliably for fuel systems on the ground. At "jet" cruising altitudes however, atmospheric pressure is much lower; hence the "differential pressure" force available to "push" fuel toward the pump is lower as well.. An extreme example - a fuel pump at 0 psi inlet pressure attempting to draw fuel from a tank (at the same height) that is also at 0 psi will not be able to do so without an "in-tank boost pump" to supply the required differential pressure. There must be a difference in pressure for any flow to occur - that's how pumps work. While it's true that aircraft with engines mounted lower than the fuel tanks can usually, but not always (depending on aircraft attitude), rely on "gravity" to supply some pressure to feed the fuel pumps, even the B757 and B767 aircraft (under wing mounted engines) with which I'm familiar normally require that the in-tank fuel boost pumps be operated continuously from before start to shut down. I'm not saying the engines won't run without the boost pumps on, but the aircraft is not "legal" for dispatch if all the boost pumps in a tank are inoperative. Additionally, if even one (of several) boost pumps in a given tank are inoperative, we're required to carry huge amounts of additional "penalty" fuel in that tank to ensure the remaining boost pumps are never "un-ported".
As for the "space or at the bottom of the Marianas Trench" statement - it's true that "pump suction" is the same, 0 psi in both places but the "outside" pressure is vastly different. The pressure in the depths of the Marianas Trench are in the thousands of psi, lots of differential pressure between the "outside" pressure and "pump suction". In contrast, the pressure outside a space vehicle is essentially 0 psi - the same as the "pump suction" (no differential pressure to do the "work" and therefore no fuel flow). Having been employed as a space systems engineer some years ago, my recollection is that to solve this problem, spacecraft fuel system tanks are pressurized with helium or some other inert gas. That gas pressure then provides the required differential pressure for fuel to flow (also, since they live in 0 gravity, there are additional problems related to keeping the fuel at the "pickup" location so that the pumps get only fuel, not the pressurizing gas...).
11:00 like a non centrifugal auto AC compressor, nice info. Regarding sports, i enjoy moto tt on Isle of Man, will be in 2 months or so. Btw, show us again your bike, maybe a story or 2, regardind maintanace. Tkanks for all your work explaning us all this.👍
If I started a series about motorcycles, would you help out? I need questions, that I and a guest would answer based on our experiences in riding, racing, building and breaking.
Jet City Moto?
Ball games are so boring, two things in life I love are the smell of new mown hay, and burning JP 1
I'd love to be a fly on the wall if you and Blancolirio met - it would be so educational and entertaining.
@18robsmith - I agree, Juan is also an A&P mechanic.
I had a couple tours working on the good old CT-133 Silver Star. Rolls Royce Nene 10 in our Canadair license-built versions, more power than the original Lockheed birds. Anyhow, boost pumps. The fuselage tank behind the cockpit in the T-33 featured a double ended boost pump. Double ended because fighter jocks in training & regular pilots flying them liked to go inverted and/or pull negative G occasionally. Although the fuselage tank is kept full being fed by tip tanks & wing tanks, when those are empty the level in the fuselage tank will drop & if the aircraft is subjected to negative G a single ended pump would cavitate. The wing tanks had single ended booster pumps to move fuel to the fuselage tank, but the tip tanks were pressurised with air to transfer fuel.
The CT-133 is the aircraft I'm in during the formation takeoff in my video called Warbird Jets. It was an awesome experience.
@@AgentJayZ Ah lucky you, I'll have to find that vid. On my tour in Baden during the Cold War I worked mostly on the T-BIrd, just a 6 month stint line servicing on the 104. I had the pleasure of many back seat trips in the T-Bird. Never lucked in for a 104 ride though.
3:00 I couldn’t care less for sports either.. and I also had WW2 planes hanging from the ceiling in my room! That’s not so weird… Watching a bunch of 20 to 30 year olds in tights run around and chase a ball.. now that’s weird!
Good you mention blancolirio, I also watch his channel.
Common rail diesels have a low pressure boost pump and an engine driven high pressure fuel pump.
Entertaining as always Agent Jay Z
On the D.G. Probable Cause channel from cockpit audio the Challenger pilot didnt ask for Prist when it took on fuel, causing it to gel in the tanks and eventual fuel starvation.
This video is about boost pumps.
@@AgentJayZYou spoke about the Challenger fuel system and the plane fueling up before it took off. I wouldn't have added pertinent information if you hadn't brought it up first.
OK, I was not trying to figure out why the crash happened. I was only trying to explain what boost pumps were. Because Juan mentioned them without saying much else about what they were.
Hello...
Why is it possible for something to malfunction in a car's engine and it stops in the street even though it is new or has been given proper maintenance, but this cannot happen in airplanes where the engines stop suddenly (except rarely)? Is the difference in the nature of the design and maintenance of the parts or in the level of maintenance?
Hareth / Iraq
Higher safety margins, lower allowed tolerences, better QC, redundant systems, R&D. It's why turbine engines specifically for aircraft (vs. internal combustion engines, or even industrial gas turbines) cost so much.
Well, the only time(s) I've had an engine cut out on me when driving was when I was very sloppy over maintenance.
I've had an ignition coil fail on a new vehicle, stopping it in the street. Once running, a jet no longer needs its ignition system.
But, yes. Design differences. Jets and piston engines are different in almost every way possible.
@@AgentJayZ -- Well, I "conveniently" forgot to mention that most of the time car engines are at a glorified idle. But I've going up some long "20 minute" grades at times. An aircraft engin operates at 50 to 75% most of the time.
@@AgentJayZ Thank you, and thank you to all who responded
I must live under a rock, not sure what the one thing is, but loved the video. In new cars with direct injection the pump in the fuel tank is a low pressure fuel pump (lpfp) and it feeds another pump that is usually mechanically driven called the high pressure fuel pump (hpfp)....so the lpfp is kinda like a boost pump =) Anyways, good stuff!
8:12 I have to say I've never heard anyone saying gas turbines don't use a lot of fuel. Maybe they're referring to thermal efficiency vs. other engines; more energy output per kg of fuel.
Well, you are lucky. those idiots have threatened me.
@@AgentJayZ Sorry to hear that
@@AgentJayZ - Threaten you? Seriously? What a bunch of morons. These are the idiots who believe jet engines don't use fuel, right?
@@wickedcabinboy Of course it's them. The number of conspiracy lunatics drives me crazy and they are generally not nice people.
Ive been watching you for awhile and i want to get into fixing/rebuilding turbines for a hobby. What engine would be good to start with?
Something small, like a T58, a RR Viper, a Garrett TPE 331, or an Allison 250 C-18. You need to be able to fond the overhaul manual, and a source of parts. Donor engines will save you hundreds of thousands. The used market in the aviation world is still extremely expensive, so you will need to become a detective to find the stuff you need.
Check out Darren Duncan's channel where he did an amazing job on his surplus Fairchild J44.
The OH manual, and the illustrated parts catalog are an absolute must. Look for those first at places like eflightmanuals.com.
If you are an extremely talented technician, and have "all the tools", and think you can figure it out on your own, I wish you luck, but failure and financial loss is a certainty in my opinion.
You have been advised by someone who does this for a living.
@@AgentJayZ thanks for the very informative reply! I have a home machine shop and im an engineering student so im more prepared than most. Im not gonna do this to make money, just for fun and to learn how the technology works.
I have a Question, What is the importance of setting a N1 power setting for takeoff and climb i get mixed answers on this some people say as long as you don't exceed ITT or max limits on N1 N2 your fine but in the books there are power setting for takeoff and climb are those just for calculations or hard numbers thank you very much
Don't know what engine you are talking about. With a turbofan engine, thrust is mostly proportional to N1, which is the speed of the LP compressor, which is also fan speed.
If you are looking to run the engine at max... right to the ragged edge, then EGT, and the speed limits of both shafts are your "redline". But as I understand it, each flight of each aircraft type, with each type of engine has a calculated optimal power setting.
If you underpower, you might not make it.
If you overpower, you are wasting fuel and causing more than necessary stress and wear on the engines.
Thank you for the response I was asking for a p&w jt15@@AgentJayZ
Interesting also that in the small engine world ( I do mostly lawn care- the twin cylinder small engines, up to 1,000cc ) and the lil vacuum fuel pump supplies about the same...3-5 PSI but at a higher volume the engine can use. Any more and it'll blow past the needle and seat in the carb. The fuel injected engines can use the same pump, but that feeds into a high pressure module, the output is right at 39 PSI to feed the injectors. The module is electric, and controlled by the ECU.
The only Super I watch is Supercross.
GREAT VIDEO, as usual. You grew up just like me. I LUV B25s too. What's your favorite WW2 Fighter?
P-47 thunderbolt and DH Mosquito are tied for first place, in my ranking.
Would "that thing" be TS?
So in diesels that have direct injection 50% of the fuel returns to the tank to keep the injectors cool...do jet engines use fuel recirculation to keep the injection system cool?
No. There is a return from the fuel control output to the pump inlet. Fuel flow is high, and generally fuel temp is about room temp, so the fuel control has no specialized cooling ability.
Not all diesel engines return large quantities of fuel or use it for injector cooling. Practically all have a return line to collect leak off fuel (all plunger pumps leak) and return it to the system but that might only amount to an occasional drip. It all depends on the engine design. Turbine engine aircraft often use fuel as an oil coolant so heat is added, not removed. "Room temperature" for an airliner cruising at high altitude may be 60 or 70 degrees below zero and wing tanks rapidly cool in the airflow. Take a look at the bottom (sometimes top) of the wings of an aircraft that has just arrived at the gate after a transcontinental flight and you will almost certainly see frost in the shape of the remaining fuel level. This doesn't apply to SR-71s of course, they had exactly the opposite issue.
I watch Hoover and Blancolirio. The other good one is Aviation Safety Detectives
Are fuel boost pumps left on once the engine is running
I think that fuel supply units are very clever even on older engines no matter what the throttle selection is
Boost pumps ensure a reliable source of fuel for the fuel pumps. Fuel pumps are not necessary at all when the engine is not "running".
@@AgentJayZ thank you
It all depends on the airframe manufacturer and becomes part of the Pilot's Operating Handbook or aircraft operations manual. Some say that auxiliary or boost pumps must be on for takeoff and landing then selected off at some point, some are selected on before takeoff and turn off automatically so they remain in a standby condition unless fuel pressure to the engine driven pump decreases. There are any number of combinations and procedures, all of which are dictated by the airframe manufacturer as part of the certification process.
@@oldtugs bell jet Ranger
Alison 250 turbo shaft
Has two of them
A small number of twin engined helicopters were built as the Twin Ranger model. Not very many.
In hydraulics we call them charge pumps.
has to be the flyover... that one thing
A Boost pump can also be found inside a surge tank.
A down is when the ref lays the ball "down" on the field.
Liking the content Jay
Well, right now, I'm at Heathrow waiting for my flight to Singapore,on a British Airways B.787 with Trent 1000s. BA, please bring back the A380s on this route. The 787 is a noisy little thing, compared to the 380, and the 777s, even those with Trents weren't much better.
You might want to check out "Greg's airplanes and automobiles"
That one thing... Could agentJayZ be a swiftie???
Otherwise I'm clueless
Also, yep generally in port fuel injected cars, you're exactly right, the fuel pump in the tank is the only pump. On cars with direct injection (diesels and newer gasoline cars) there's a second high pressure pump mechanically driven off the enine to provide the >1000 psi required for the injectors
I don't listen to her music, but I am impressed with her humanity.
@@AgentJayZ LOL. And her humility. She's practically a monk.
Get schwifty.
Not a fan of sports, a fan of fan's, the big spinny type
A down is the condition of the center being over the ball which is positioned on the ground.
Thanks. "the condition of the center being over the ball"? Gibberish.
The center of what?
So the offensive team (the ones that start with the ball) has 4 attempts to gain Ten yards distance towards their goal line. Normally when they talk about gameplay you’ll hear the number of down which the offensive team is playing, and the distance they have yet to traverse before they can restart the count of “downs”. Now it can be a number greater than ten if the player with the ball runs away from the starting line as well IE “1st and 15”.
I only played football because my friend did, otherwise could not care less about the sport.
Much better. Thanks!
I subscribe to all YT creators you mention in this video. Wierd coincidence or proof that just pure relevat content pays off? Maybe wrong english but you get the point…
Many of the booster pumps are gear drive. They use a spring relief bypass to regulate pressure.
When I describe fuel pumps as gear driven, I mean they are attached to the engine, and driven from a gearbox literally attached to the main shaft of the engine via a radial drive shaft.
Boost pumps are in the fuel tanks, and electrically driven. They are nowhere near the engine.
@@AgentJayZ Sorry, I meant to say gear type, not gear drive.
Greeting. I love watching your shows. I have one request / question.
Why don't you at least enable automatic translations.
Automatic translations from English work well now, so you can understand everything you're talking about.
It's not my place to get angry, but you're not a TV presenter to have your voice mixed perfectly. However, while you are speaking, the machines are buzzing, you are turning... and then people who do not speak English as their first language have problems.
I would beg you to just open the automatic translation option. You don't have to write your speech in English.
The program translates from your pronunciation
I will look into it again, but so far the automatic subtitles are garbage. So inaccurate that they are not useful, and just annoy me.
A lot of what I do is to straighten out misunderstandings about how these machines work. The subtitles only add to that misunderstanding.
Why would I think audio translations are any better?
Moto GP is cool tho' 👍. B-25 Mitchell for the win.
Like you I am interested in airplanes, engines.... etc
❤
Your not weird bud us gear heads are a bit different id rather turn wrenches and study maintenance manuals than watch sports.