Grumman F8F Bearcat US Navy Superprop!

greetings this is greg the grumman f8f bearcat was too late to see combat during the second world war it's what i consider to be a super prop that is to say it's one of the planes that represents the zenith of piston-powered fighters that came out just a bit too late to see action during the war i have a previous video on this category of airplanes which covers the north american p-51h mustang which was not a normal world war ii mustang it's a different airframe they just look similar i also talked about republics xp 72 and others i originally planned on this video covering all of the us navy super props but the bearcat for reasons which will become clear really needs a video of its own so here we are now before we go any farther i need to get this out of the way the bearcat is not an improved wildcat hellcat or anything else this was an entirely new breed of cats so to speak it's hugely different from the hellcat in terms of design philosophy and execution grumman's previous fighter plane the hellcat was a relatively low-cost airplane by us world war ii fighter standards the hellcat was designed to be quick to produce and relatively inexpensive this isn't to say that the hellcat wasn't a quality airplane it was but certain sacrifices to performance were made in the interest of assembly line time and cost now this worked out really well as initially hellcats were around fifty thousand dollars a copy which was a decent deal but the price quickly dropped to about 35 000 a plane as the production was streamlined this was at a point when corsairs and thunderbolts were more than double that amount in terms of value per dollar the hellcat was probably the best u.s fighter of the war not the best fighter overall but in terms of bang for the buck heck in 1944 even a p40 cost more than a hellcat and the hellcat was far more capable now the bearcat was another story it was up around 83 thousand dollars a copy even more than the famously complex and difficult to build corsair i think the bearcat represented a new way of thinking and a new direction in regards to warplane economics at grumman i don't have a source to show this is how they were thinking at grumman but hear me out if you're buying warplanes there is a quantity versus quality equation you have to think about do you want to buy a few really expensive airplanes or a larger number of inexpensive but less capable airplanes there are cases when buying a greater quantity of slightly inferior planes may be the way to go especially if the extra expense is going to be in capability you won't need anyway as an example as compared with the hellcat the p47 thunderbolt is more than twice the price but has significantly more capability at very high altitudes and a lot more range but you have to ask if i'm not going to be fighting up at high altitude anyway say we're going to use these planes in an environment like the eastern front in europe where most of the combat is close to the front and at low altitude would i rather have eight hellcats or four thunderbolts the answer is eight hellcats no question about it provided you've got enough pilots for them but now think about aircraft carrier warfare we can only fit so many planes on that carrier so in this example do i want 20 of the most capable fighters to deal with incoming threats or 20 slightly inferior airplanes i think the answer is self-evident and when dealing with the emerging threat of kamikazes every second started to really count and i think grumman made a shift towards more expensive fighters which continued on pretty much as long as they built fighter planes this line of thinking culminated in the f-14 tomcat which was at least three times more expensive than the f4 phantom it largely replaced in the fleet defender role some say the tomcat was 10 times more expensive but these numbers are a little tricky to pin down it looks to me like that 10 times more expensive number comes from the package deal of tomcats to iran but those included a lot more than the planes themselves either way though the tomcat was very expensive but it sort of makes sense when you consider what was at stake when it was launched to intercept incoming threats to the fleet and due to space limitations on the aircraft carrier launching say three times as many f4 phantoms or f8 crusaders or whatever simply wasn't an option as grumman as grumman was focused on carrier aircraft i think that's sort of how their line of thinking went and i think it started with the bearcat furthermore by the time bearcat development was really rolling they were probably thinking about post-war markets for their products i suspect they realize that in the post-war environment they would be selling far fewer airplanes so it makes economic sense to try and sell more expensive planes history has shown us that of all the us companies that built combat planes in world war ii grumman was one of the most financially successful in the post-war environment so i think they knew what they were doing when they shifted to fewer more expensive airplanes that's enough about my economic theories and that's all that was is my theory let's move on to the plane itself in period publications at the time it was said that the new bearcat was a combination of the best features of japanese fighters combined with the best of us navy fighters the bearcat wasn't mentioned all that often in period publications all the excitement had moved over to the jets by that point but when it was mentioned the japanese influence was often brought up and there was some influence from the japanese but i think there was stronger influence from the german fighters and from the corsair grumman wasn't operating in a vacuum they had been looking at planes from the competition which any prudent manufacturer would have been doing in fact they had on occasion had the opportunity to inspect very closely the xero fw 190 and of course the corsair yes i know some of these opportunities didn't happen until after design work on the bearcat had started but that doesn't mean that the people at grumman hadn't seen these planes before or that they didn't make changes during development as they learn new things now it's said that the inspiration for the bearcat came about from a conversation between jimmy thatch the pilot of thatchweedfame and the vice president of grumman thatch explained that climb rate was of great importance to a carrier-based fighter plane which is true and it's very apparent that grumman focused heavily on climb rate for the new bearcat if you've been watching this channel for a while you may recall that an aircraft's maximum rate of climb is a function of the difference between power available and power required at the time the bearcat was in development the most powerful engine grumman could source to put into a fighter was the pratt whitney r 2800 which was the type already in use in the hellcat and corsair so increasing the amount of power available in the bearcat over those other planes didn't seem like it was possible even if they put in a newer and more powerful version of the r2800 it was likely that version could go into those other planes as well so the bearcat wasn't going to have an advantage there at least not much of one that leaves power required well the best way to reduce power required was to lower the weight of the airplane all airplanes are a series of compromises so what would they be willing to sacrifice in order to decrease the weight they didn't sacrifice armor in fact the bearcat had armor that could stop 50 caliber fighter it's one of the very few world war ii fighters that had armor that tough so no compromise was made there self-sealing fuel tanks add a lot of weight but combat during the war had shown that's a sacrifice to performance worth keeping especially with everybody uh throwing around incendiary or explosive ammunition so they did use a self-sealing tank in the bearcat but only a single 185 gallon tank that isn't a lot to put that into perspective let's think about the fleet defense mission on takeoff and initial climb out it's going to burn about 5 gallons a minute or 300 gallons per hour shortly after takeoff it's going to throttle back to maximum continuous power at which point it's going to be burning around 170 gallons an hour with occasional spikes at war emergency power back up to 280 or 300 gallons an hour thus on internal fuel a bearcat in this type of mission has an endurance of only about 45 minutes from takeoff before the pilot has to seriously think about landing of course if he's loitering at altitude he can extend it a lot by throttling way back flying at an economical speed and manually leaning the mixture under these conditions he can get the fuel flow down into the mid to low 40s range the plane won't be going very fast but this will extend the plane's endurance quite a bit still the range was a big step back from the corsair and hellcat it was actually a lot like the early bf-109 this was a sacrifice they had to make in order to get the performance they wanted i'm not saying this was specifically due to the influence from the german fighters but going with a smaller airplane with less fuel capacity was very much the german way of doing things of course the bearcats range could be extended with drop tanks but remember that only works so well because once in combat with enemy fighters you have to drop those tanks and that means that no matter how much fuel the plane can carry in the drop tanks its maximum distance from base in a combat mission is limited to the amount of internal fuel it carries minus whatever it used in combat that's the reason the thunderbolts had a 300 had 370 gallons of internal fuel laid in the war and even more with the dash n or november models the bearcats burn fuel at a similar rate to the thunderbolt but only have 185 gallons so that was a big limitation now how else did they make the plane lighter well they simply made it smaller i'll put up some numbers so you can see how small it is relative to a hellcat or corsair of course this sort of ties into the issue of smaller fuel tanks a smaller plane has less room for fuel note that the bear cat is more than five feet shorter than either of the other two planes here and it has quite a bit less wingspan as well this decreased size contributes to the bearcat's lower weight it's not the only reason but it's part of the equation for fun let's throw in some european airplanes sadly for comparative purposes there were no proven navalized versions of german fighters there were some experiments and yes i know about the half dozen or so 109 ts show me a picture of one taking off or landing from a carrier and we'll talk the bearcat and fw 190 are actually pretty close to each other in length and wingspan with the 109 being a little bit smaller but i would say still in the same ballpark so while the bearcats dimensions were small for a u.s fighter they were about par for the course for a german fighter if we compare weights well the germans are lighter but that's largely because they were not naval variants no folding wings no arresting gear no need to reinforce the structure for the abuse of a catapult or a resting wire also the germans were pretty good at saving weight and simplifying production in fact the single best feature of the bf-109 is one that's almost never mentioned they were cheap and easy to produce of course they were also pretty light which really helped the climb rate next let's throw in a supermarine seafire but not just any seafire but the nearest thing supermarine had to a bearcat this is very much a british super prop it's actually quite a bit faster than the bearcat the sea fire may look really heavy here and it is by seafire spitfire standards but this version has the rolls-royce griffin it has dual contra rotating props and hydraulically powered folding wings as well as all the other naval type stuff so it's a lot heavier than a typical spitfire but it has the performance to make up for it so the bearcat is the lightest naval fighter here but not too much heavier than the land-based fw190a8 size had a lot to do with that but there's so much more some of the next weight reduction methods may surprise you one of them in particular i think is absolutely insane at least in my opinion but you can be the judge of that way we get to it you might want to be sitting down before we get to the insanity let's talk about the engines there were two different engines in the bearcat as a general rule if it's a dash one variant it's packing the r2800-34w if it's a dash 2 bearcat it uses the 2800-30w so the later-2 bearcat uses the lower dash number engine i want to start off by talking about that first one the dash 34 used in the earlier airplane note that the higher dash number in this case 34 versus 30 is the earlier engine opposite of what they normally did thanks brad and whitney so the 2800-34w was the latest and greatest of the mighty r2800s at the time it's a very rare engine in fact i don't think it was ever used in any plane other than bearcats here's the power chart for the dash 34 engine it makes 2300 horsepower at 58 inches of manifold pressure and at 2 800 rpm that by itself isn't news the p47s with earlier r2800s were making the same amount of power at the same manifold pressure but at only 2700 rpm and two years earlier the difference here is that the bearcats engine is doing this without water injection i don't know what changes they made to these later dash numbers used in bearcats these are such rare engines that i can't find any specifics on them i do know of course there's still 18 cylinders same bore and stroke but i suspect the valve timing changed slightly along with improved superchargers but i'm not sure of course 2300 horsepower is still pretty good but when it goes into war emergency power which the navy was calling combat power at this point the water injection kicks on and it allows a maximum of around 70 inches of manifold pressure and around 2750 horsepower i'll show the difference this makes in speed later on it's very eye opening for now we're still talking about weight now you might say what does this have to do with weight an r2800 engine is an r2800 engine as far as weight is concerned true they may vary a little bit in weight from one dash number to another but not much the weight savings in the case of the bearcat is in what they did not add to the engine the bearcat has no second stage supercharger and associated drive mechanism now you might initially think that's crazy the wildcat hellcat corsair spitfire mark 9 thunderbolt lightning all had two stages of supercharging a single stage system is very 1937 and would normally be thought of as hopelessly obsolete in 1945-46 however as with all this stuff it's just not that simple by the way if you haven't already seen it you may want to watch this video it covers all the basics of these different supercharging systems i can't really go over all the fine points of these systems in every single video i make so i assume for the sake of brevity in these videos that the typical viewer here has already seen this video or maybe my p47 series which also lays the groundwork for all the subjects i tend to cover on this channel if you didn't watch those other videos then for now just know that multiple stages of supercharging allows for more power through a greater altitude range than a single stage system so why a single stage system in the bearcat well it's quite simple by 1943 it had become pretty obvious that almost all naval air combat was taking place below 20 000 feet attacking aircraft would have to come down well below that to attack ships so there just wasn't much need for naval fighters to have a lot of high altitude performance but they didn't know that when they designed the wildcat and the corsair at that time there was concern that level bombers would be able to attack ships at sea from very high altitudes 25 000 feet or so that very rarely happened and the axis didn't have any bombers that could do it anyway by the time the bearcats development was underway understanding of naval air combat had evolved why add the weight of a second stage system if you wouldn't ever use it now if bearcats had to fly over germany or escort b-17s this would have been foolish but it didn't have the range to do that anyway so why bother with the second stage supercharger instead save a bit of space and wait now if you don't have a second stage what else don't you have well you don't have an intercooler and that's by definition because an intercooler is defined as a charge cooler between the stages now you could possibly have an aftercooler but i don't know of any radial engine that did and the bearcat doesn't have one anyway note that today in the automotive world people call after coolers intercoolers don't let that confuse you the point is that the bearcat has neither what it does have is a good water injection system with a 16 gallon tank let's take a look at the speed chart here line number five is for maximum continuous power and it shows 307 knots at sea level line four is for combat power 331 knots at sea level line two is for war emergency power and they kept changing these times just know that the names of these power settings just know that line two is all out which means the water injection is spraying and we can reach 366 knots which is 421 miles per hour or if using the metric system 678 kilometers per hour that's massively fast for a world war ii era airplane at sea level now as we climb the engine loses power at around 12 to 13 000 feet the pilot will switch the supercharger over to high speed to regain some of that loss power once the plane is above twenty thousand feet it's down below fifteen hundred horsepower remember from twenty seven fifty and power will continue to decrease as the plane climbs nothing can be done about it because there's only one stage and two speeds on the bearcats dash one engine now we should note that at 25 000 feet even though power's down it's still pretty fast 365 knots is about 420 miles an hour so it's not amazing up there but it's not exactly slow however it should be clear that that the plane is optimized to be a low altitude fighter below 15 000 feet it's a monster but to get that performance they sacrificed quite a bit up high in fact up at 25 000 feet many run-of-the-mill 1944 fighters are just as fast and most 1946 super props will outrun it up there with ease of course the airframe contributes to the speed as well if you walk up behind the previous fighter from chrome in the hellcat especially if you were just looking at say a p47 or a corsair the hellcat looks like it was built by a boilerplate manufacturer who made parts for ships or locomotives there are raised rivets all over the place then you might notice that instead of using compound curved panels they just used a bunch of small flat panels and attached them with a zillion raised rivets look at the fuselage here especially above the insignia and you should be able to see what i mean this is in stark contrast to a corsair with its complex compound curves and flush surfaces pretty much everywhere but then when you walk around to the front of the hellcat you might notice a big difference there was a method to grumman's madness now the surfaces all have nice curves and everything is flush grumman understood the law of diminishing returns and they really applied it to the hellcat they made everything flush where it counted the most then where it didn't they focused on ease and speed of construction this worked the hellcat performed well and as i pointed out was relatively inexpensive however the bearcat is not like this it's more like the corsair it's flush riveted and spot welded everywhere it's a very smooth airplane of course this drove cost way up but they were clearly trying to get all the low altitude performance out of it they could law of diminishing returns be damned take a look at the front of the hellcat the lower part of the cowling has three inlets the center is for carb air and oil cooling the outer pair are for intercooling in almost every test hellcats failed to make their rated levels of power with the engine installed in the airplane and i think these inlets are a big part of that i talk about that in another video which covers the corsair and hellcat performance in relation to each other in quite a bit of detail so i'm not going to rehash that here but just know that the hellcats air inlets and chunky fuselage cost a little bit of power and added quite a bit of drag but simplified construction as compared with the corsair the corsair had its oil cooler carb and intercooling air inlets in the leading edges of the wing roots normally the later corsairs with more power move the carb air to the cowl because they simply needed more air than they could get through the wing root inlets but in the pre-4 corsairs it was all through the wing roots this is more complex to design and build but superior now guess how they did it in the bearcat they're in the wing roots like the corsair and unlike the hellcat that contributes to the bearcats more sleek fuselage they provide ram air to the injection carb and those inlets that is they can brought on the bearcat they provide ram air to the injection carb and cooling air to the oil coolers of course since there are no intercoolers those inlets can be pretty small on the bearcat that's another downside to intercooling it's not just the weight it's the drag normally it's worth the wait and drag penalty especially up at high altitudes where indicated airspeed um and parasite drag are low for a given true airspeed and discharge temperatures from the supercharger which has to work really high at high altitude discharge temps are very high under those conditions so an intercooler does extra good however the bearcat isn't designed for fighting up there and at low altitude its water injection does the job of anti-knock protection really well so down low it has all the power of the intercooled engines but without the extra cooling drag and of course that extra cooling drag is an even bigger penalty at low altitudes than it is up high because of the extra parasite drag at the high indicated speeds down low now the rest of the plane has some factors that made it lightweight for example i actually think they saved weight by going with lighter brakes a carrier airplane can get away with minimal wheel brakes because they rely on the arresting gear to stop the airplane brakes work by changing the motion of the airplane into heat smaller brakes have less area to absorb the heat thus they get hotter bearcats did suffer from break fires which indicates to me that they saved weight by going with really small breaks and took the concept maybe just a bit too far the next thing i'm going to talk about is a weight savings technique that i think was just crazy to create a lightweight structure the bearcats wings had to be a bit weaker than normal the plane's maximum g loading according to this chart from the pilot's manual was about 6.3 g some sources put the limit at 7.5 this chart shows 6.3 either way it's generally lower than other world war ii era fighters most could pull 9gs or slightly more than the pilot could handle before blacking out in the bearcat the g limit was below the point at which the pilot would likely blackout however it gets worse because the g limit is much lower if the ailerons are used this is from the manual quote the maximum acceleration of 4.5 g applies to aileron operation when flying without external stores unquote i'll highlight the g limit lines for you here in blue so if you're planning to use your ailerons during a turn fight you have to keep the g loading below 4.5 while doing so have fun trying to beat someone in scissors maneuvering at high speeds in a bearcat these g limits are a big deal because turn performance at high speeds is g limited and the bearcats lower limit means that nearly all other world war ii era fighters can out turn the bearcat at high speeds now at low speeds that's not the case and in terms of sustained turn performance the bearcat is going to be at or near the top of the list but in turn performance at high speeds generally above 250 knots the bearcats turn performance is subpar however it's about to get worse that's not even the crazy part so let's suppose you're an engineer at grumman you know your new fighter has a low g limit so low that pilots are likely to exceed it how would you solve this problem i can almost guarantee that whatever solution you're thinking of isn't what grumman did they knew that wing failures due to over g would happen so they designed the wings to break off in such a way that the plane would still be flyable the wingtips would break off at a point about here this would leave the plane with enough wing and aileron to limp back to base and land in the near perfect world of mathematics and engineering both tips would break off at the same time in the real world with production tolerances and asymmetrical loading of things in flight they often didn't break off at the same time sometimes only one would break off rendering the aircraft very difficult if not impossible to control now when do you think this might have happened if you guess at low altitudes during pullouts from dives you guessed right it happened when pilots would have so little time to deal with it that regaining control of the airplane would be difficult or impossible in fact when the blue angels flew bearcats they had just such a failure during a demonstration and the pilot was killed so i'll ask you again if you were an engineer at grumman and at this point it had become clear that bearcats were crashing because the wingtips were breaking off individually and not in pairs as designed how would you address the problem well you might decide to strengthen the wings at this point but grumman's answer was to double down on this breakaway plan they decided to link both wingtips to explosive charges so that when one wingtip broke off explosives made sure the other one separated as well and voila no asymmetry at least not in theory that didn't work either asymmetry was still a problem due to system malfunctions and at some point the explosives went off with a plane parked on the ground and it killed somebody nearby at this point reason returned to grumman and they decided to abandon the whole idea they strengthened the wings and did away with the breakaway wingtips the manual isn't clear about this but i think at this point the plane was cleared up to 7.5 g's which was a reasonable limit pretty normal for a naval fighter of course the plane gained weight about 250 pounds so yes all this insanity was in an effort to save about 250 pounds most of it uh involving strengthening in the area of the wing folding mechanism on the subject of wing folding for the bearcat grumman abandoned their patented stow wing folding system famously used on earlier airplanes like the avenger which resulted in the bearcat taking up more space laterally than the much larger grumman avenger but they really had to do that because the farther out you move the folding mechanism the less stress it takes from the g-loading and remember they were trying really hard here to build a lightweight structure of course this also helped with the landing gear problem the bearcat uses a pretty complex inward retracting landing gear it's a quasi-telescoping type it sort of unfolds on itself as it extends to gain some extra length so the giant aero products propeller will clear the ground on the subject of that prop it was selected because the aero products prop was lighter than the curtis or hamilton standard constant speed units now the bearcats most outstanding performance feature by far is its rate of climb the early-1 planes at war emergency power had a climb rate at sea level of 5600 feet per minute the rate would decrease to around 4 200 feet per minute at 8 000 feet which was still pretty good so good in fact that the bearcats held the record for time to 10 000 feet for about 10 years during that time jets were trying to beat it but could never quite match the bearcats 94 second time to 10 000 feet that's an average climb rate from brake release to 10 000 feet of 6400 feet per minute now you might notice that the official climb rates for the plane don't support such a fast time to ten thousand feet that's because when manufacturers go after these climb records they usually use specially set up airplanes grumman certainly did that as well it's said that grumman used a production production-one bearcat for these tests of course nobody says what they did to the production plane before the tests um i'm not even so sure it was a bearcat they may have used what was technically a grumman golf hawk the golf hawk was a civilian version of the bearcat yeah there was such a thing it was built with no guns no armor and almost certainly no self-sealing fuel tank i'm not sure if that's what they did for these records and only two golf hawks were built but in any case it was clearly if not a golf hawk a specially prepared production bearcat that set the climb record i suspect the weapons and armor were removed at the least just to further confuse things though golf hawks were almost always while the two of them were almost always referred to as bearcats and there was another earlier grumman airplane called the golf hawk golf hawk or specially prepared bearcat either way you might be asking why the jets had such a tough time beating the bearcats climb record i mean for a record to last 10 years back then that was a huge amount of time well i suggest watching my video on the f-14 tomcats horsepower the short version is that rate of climb is a function of power available minus power required and the faster a jet goes the more power it has which in itself is a pretty complex subject so to reach their best climb speeds jets have to accelerate quite a bit keep in mind we're talking about rate of climb not angle of climb now propeller airplanes have their best rate of climb speeds quite low so almost right after takeoff right after liftoff the bearcat can start heading up to ten thousand feet at its best rate the jet has to accelerate for a while to reach its optimal speed during that time the bearcat gets in the lead and the jet just can't catch up until now the race is over at 10 000 feet they kept announcing these bearcat versus jet contests in period publications yet those same publications never published the results of these contests after they happened in their subsequent issues i think that's because they were expecting the new jets to win and it may have been embarrassing for their biggest advertisers that the bearcat kept beating the new jets on this particular page i think it's a funny coincidence that the page opposite has an ad for sodium filled valves the bearica the bearcat does have sodium fill valves although i have no idea if they were made by eaton or not now i must say that the bearcat beating the jets in these contests was partially a function of the way the contests were held they went from break released on a runway to ten thousand feet that's how they had been doing it since before the jet age and i think that's still still how they do it and it does make sense to do it that way but had these contests been done in almost any other way the jets would have beaten the bearcat from fairly early on for example if both planes were starting from cruise speed or from maximum speed or even with both planes at the same speed say 300 knots the jets would have taken that record much earlier this is really a question of that power versus thrust equation i explained in at least two other videos so no need to cover it here i should mention that a lot of these period magazines including some of those in this video as well as the bearcats pilot manual and some other u.s navy bearcat data are in the patreon section so if you want to do more research on this or just read the same stuff entire in its entirety from the original source i've made it pretty easy for you now let's move on and cover the changes for the bearcat dash 2 variant i'm not going to break down every sub variant frankly i think that would be a little bit dull i'm going to generalize here the dash twos usually have the following upgrades although some of these features can be found on certain dash one sub variants there's some crossover here so again generally speaking the dash twos have quad 20 millimeter cannons instead of the quad 50 calibers often found on dash ones quad 20s were a huge upgrade as the quad 50s were so 1942 and not really up to the job anymore the dash twos also have a taller vertical stabilizer and rudder personally i find this really hard to see in pictures when i look at two pictures side by side i can kind of see it if their angle is right from the side but in any case the size and shape of these things in the dash 2 is a bit different in this magazine from january of 1949 it said that the bigger vertical stab and rudder were related to the upgrade to the 20 millimeter cannons keep in mind that while these trade publications are technically primary sources they are not 100 percent reliable and certainly not equal to official navy or grumman documents but i include the magazine stuff sometimes because it's interesting and often it's the only way to date certain events speaking of dates i'm not sure when the bearcats all had the strengthened wing the blue angels cat crash was in 1946 so i imagine the wing improvements happened shortly after that the dash twos came out in 1948 so i strongly suspect all the dash twos were built initially from the factory with the stronger wing the big change for the dash 2 was the engine it had the pratt whitney r 2800-30 like the engine in the dash 1 it runs a single stage supercharger no intercooler but water injection instead of the dual speed supercharger though it uses a variable speed drive unit the dash 2's engine also features an automatic engine control unit usually called an aec in principle it's a bit like the german systems used during world war ii this is an engine management system that reduced pilot work workload the throttle which was called the boost control lever on an aec equipped bearcat which again is just some of the dash twos that was used to set manifold pressure values say you set it at 42 inches and when climbing or descending the system would use the hydraulic coupling of the variable speed supercharger to maintain the manifold pressure setting in other words when climbing or descending the pilot didn't have to constantly adjust the throttle lever aka boost control lever in order to maintain a given manifold pressure value it had other workload reducing functions as well for example in many cases the pilot could adjust engine rpm without having to move the throttle first or vice versa this is all very similar to what was in the 109 and to an extent the fw 190s dash 2 bearcats with the aec would not have supercharger speed controls on the instrument panel as supercharging supercharger compressor speed was controlled by the aec via the supercharger's hydraulic coupling the dash ones did have a supercharger speed control in the cockpit in those planes the pilot had to shift the supercharger speeds manually from high to low now the dash twos without eec had a three position supercharger switch marked low intermediate and high but the dash two with eac and i know this is a bit confusing but the dash two with aec um which also means that a variable speed supercharger drive mechanism had what was essentially like what the germans had been using on the bf109 a single stage system with a variable speed drive i have an entire video about the 109s supercharger speed control and it's kind of funny to me that the anti-109 crowd often criticizes the system saying that if variable speed drive was so great why didn't the allies copy it well they did the later bearcats use it the xp-72 used it and the later corsairs used it it was superior it just took a while to adapt that technology to u.s engines of course there is a penalty in drive cost for the variable speed supercharger so in some ranges it costs you a bit of power but throughout the altitude range it provides an overall advantage which is why it was used the dash twos with aec have 2500 horsepower um at war emergency so that's 250 less than the dash ones but they do it with a bit less manifold pressure and still have more power throughout the altitude range in spite of having 250 less peak horsepower of course the dash 2s are also heavier about 330 pounds heavier that's not too much but it's not nothing either let's graph the speeds of these two planes side by side the dash 1 versus the dash 2 with the 30w engine and aec the green line shows speed for the dash 1 the orange line is for the dash 2. as you can see the extra power of the earlier dash one version's engine plus less drag from the smaller tail and to a very small extent the lower weight all combined to make the original variant quite a bit faster down at sea level at least based on the test data that's available however from about nine thousand feet on up it's all dash two that variable speed supercharger pays big dividends note that on the actual navy chart for the dash two that line has a bit of a more smooth curve to it due to the variable speed drive i'll post the original chart at the end of the video my graph skills are not all that great but this chart is accurate to within about two knots of the original anywhere on it and of course this makes it easier to do side by side comparisons so yes the bearcat was influenced by japanese fighter sure in the sense that keeping weight down was a priority however i would say that the plane's construction and drag reduction techniques are very much like a corsair its supercharging system that is to say its single stage system with no charge cooling and driven by a variable speed hydraulic coupling backed up by water injection is very much bf109 also the bearcat uses a single spar wing design also very bf-109 i suppose there's some fw 190 influence in there as well at least in terms of the plane's general layout in conclusion the bearcat was one of the first super props it had amazing klein performance and great speed below 20 000 feet it was an expensive airplane and did have some real sacrifices in its design to get the weight down and the climb performance up some of these sacrifices paid off some of them like the breakaway wings really backfired on them the us navy never flew this plane in combat however the u.s navy did deliver bearcats to the french in saigon where the french used the plane in combat during the french indochina war which would we later know what happened with that little is written in the english language about the bearcats performance in that war but i don't think they saw any air-to-air combat i could be wrong but i haven't found a shred of evidence for that of course like nearly all fighters the bearcat could deliver air-to-ground ordnance but it didn't carry all that much furthermore it had very short range so it was really only useful and highly effective in that close in fleet defense role for which it was designed with its low altitude speed climb rate and firepower it could do that really well but with the new jets coming in the bearcats place in the u.s navy just didn't last very long bearcats production ended in 1949 now the bearcats primary us rival was the corsair and the corsair was a more attractive option for most buyers both planes were on the way out but the corsair stayed in production three years longer into 1952. it's hard to say just what version of the corsair i should compare to the bearcat in fact deciding what version of anything to compare to anything else is always a touchy subject the corsair dash iv was the final version to see combat during world war ii but it did see combat in the war and the bearcat didn't so for comparison i'm going to go with the corsair dash 5 which came out in late 1945. i'd really call it a 1946 airplane the corsair dash 5 had the pratt whitney 32w which is a bit like the 30 w in the bearcad dash 2 because both are r2800s and both use the variable speed supercharger drive however the corsairs supercharger is a two-stage unit and it's intercooled interestingly the only picture i can find of the 32w engine shows that it drives the extra stage at a 90 degree angle to the crankshaft how german of them i'm not sure if it was actually set up like that in the corsair or not i haven't been able to find a left side picture of the corsair dash 5 with the cowling off now you can probably guess what's going to happen when we add the corsair dash 5 speed to our chart here you go sure the bearcat is a lot lighter but that two-stage and intercooled supercharger setup in the corsair just dominates the bearcat except against the dash one version when down below 6000 feet furthermore the corsair can carry far more ordinance has a lot more range has a much larger water injection tank so it can run at those higher power levels longer during world war ii one of the corsair's biggest faults was its horribly non-user-friendly cockpit i'm not going to say it had the worst cockpit of world war ii fighters because there is some real competition for that title but it was really bad but starting with the dash 5 they fixed it and it became really good about equal to the p51 or maybe even the fw190 and that's saying a lot i don't want to turn this into a corsair dash 5 video and that's not even the last or greatest corsair but i think that the comparison shows that the bearcat was awesome within the confines of its very specific fleet defense mission but in the big picture it really couldn't compete with the contemporary corsairs in fact they kept hellcats around because um after the bearcats were in service because of the range issue i would argue that while the bear cap may have been one of the first super props well it was one of the first ones but it just didn't have enough capability to be called the best one however grumman had another super prop to throw into the ring and the british had several so we're gonna see how those stack up in future episodes on this channel the british sleeve valve technology was really starting to mature in the super prop era so there are going to be some interesting comparisons uh coming on this channel thanks for watching and extra thanks to my subscribers i really appreciate you guys i appreciate all the comments and especially i've got to give thanks to my supporters on patreon they're really the ones paying for this channel and driving the direction it goes patreon supporters of course get early access to the videos that way i don't miss their comments and they get access to the original source documents used in the production of the various videos on this channel that's all for now have a great day goodbye you

Channel: Greg's Airplanes and Automobiles

Views: 382,122

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Id: Nv-sEmEGPL0

Length: 46min 49sec (2809 seconds)

Published: Wed Jan 19 2022