I’m just pondering some things that I read in the DH Hornet book that I bought that was of course co-authored by David Collins from the Hornet project.
I’m mainly wondering about the passages where the Hornet was designed to have a wing-loading of about 42 lb/sq ft. According to the RAF, when tested, the Hornet has a loading of more than 44 lb/sq ft, and that effected it’s turning radius and especially roll-rate against the Spitfire XIV and the P-51B/Mustang III.
I read in the early sections of the book that the Mosquito was comparatively maneuverable to the Spitfire, Tempest, Typhoon and FW-190. Keeping in mind that the Mosquito was larger than the Hornet and of roughly equal wing loading, one would think that the Hornet would be as if not more agile and be easier to fly.
However, it did seem that roll-rate would be a bug bear of the Hornet in terms of agility and handling, having to overcome rotational inertia of having it’s Merlin engines wing mounted. However, that does lead me to wonder about two things.
Firstly, I wonder why power-boosted controls were never considered. The Lockheed P-38 Lighting had power boosted ailerons from late P-38J batches onwards, and those remarkably improved roll-rate and turning radius compared to the Bf-109G and the FW-190A, to the point where it could outmaneuver them, and the Hornet and P-38 were about the same size. So it, in theory at least, would stand to reason that the Hornet would’ve benefited similarly, at least on paper. Also, the DH Venom jet attack fighter used power-boosted controls to overcome a slow roll-rate because of it’s wing-tip fuel tanks.
The North American P-/F-82 Twin Mustang also had power-boosted controls to over come a feared shortcoming in terms of roll-rate and turning radius, and to allow each pilot equal ease of operation. This also was used to overcome the fact that one side of the aircraft weighed more than the other when rolled about one fuselage. And the F-82 was rated as highly maneuverable for it’s size (it was a bit larger than the Hornet and had a bit higher wing loading).
Of course, we can also argue about flaps, such as those of Fairey-Youngman or Fowler design, which was tested on one DH 103 prototype but went nowhere, as the Hornet was fitted for production with more or less conventional split flaps.
I also read late in the book that one DH technician was critical of the RAF’s suggestion about an aileron hinge design, saying that the Mosquito’s was likely better from a feel and function standpoint, and the Venom reverted back to the Mosquito type hinges. Could that have possibly made a difference.
Of course, comparing the Hornet to the Spitfire or the P-51 Mustang is sort of acedemic, as it’s more important to see how it would’ve done against the Hawker Tempest (a single seater in the same broad size class as the Hornet) or the P-47 (as heavy or heavier than the Hornet), and, especially, the Me-109 or the FW-190, which were highly loaded single seaters, and IJA and IJN fighters such as the Kawasaki Ki-61/100, Nakajima Ki-84, Mitsubishi J2M, and of course, the Nakajima Ki-43 and the Mitsubishi A6M Zero, and above all, were the Hornet’s potential enemies.
Of course, the Hornet was judged to be a better interceptor and high-speed attacker of aircraft than a normal dog-fighter, but could it have been improved in that respect without a major redesign, and the only rough allied equals were the F-82 Twin Mustang, P-38 Lightining, and the DH Mosquito, which the Hornet never flew alongside, and neither the Hornet or F-82 saw any WWII combat. And trying to judge how both would’ve done–with or without certain features–may be futile but none the less interesting, as the Hornet and the Merlin-engined F-82s were contenders for fastest piston engined fighters.
By: ChernKStewfan - 15th February 2012 at 16:29
Sorry to try and revive that dead thread, but I think I might have a lead on what John Wimpenny said about the Hornet’s ailerons in the DH Hornet book and why he didn’t approve of the type used on the Hornet.
I was asking about some of the developments of the DH Vampire and Venom in another thread, and the subject of power boosted ailerons were brought up. It seems that DH were investigating that issue shortly after World War II ended, and the DH Swallow research aircraft lead DH to put more research into the project after John Deery flew the Swallow.
This connects to the Hornet’s aileron issues in that DH suspected that as speeds rose that things such as compressibility and flutter (a then little known aspect of transonic flight) would become major issues. The Venom there for was fitted with ailerons that had the convexity deactivated by extending the wing trailing edge back a certain amount.
Could the Hornet’s ailerons been experiencing the effects of flutter at high speeds due to compressibility or some other factor? Because DH went from using convexity ailerons on the Vampire and Hornet, but ditched it on the Venom and also used power boosted controls, in part it seems to counter high speed flutter issues and compressibility, or at least that’s the problem that they were hoping to solve or reduce. It may not have been a big issue on the Hornet (which combined with it rapidly approaching obsolescence is why DH didn’t put a lot of effort into fully solving the issue), but it seems to maybe have pointed out something that would become a big problem later as jet engines became more powerful and new jet fighters and bombers became much, much faster than any piston engined fighter and the WWII era jets.
Edit: I finally found out what convexity is and why it was felt by DH to be a not very desirable feature. Convexity was basically fitting a blunt trailing edge to control surfaces (namely the ailerons) instead of the then more common tapered edge. This was felt, due to production issues related to the design, to be a source of trouble on the Hornet according to Wimpenny’s commentary. How this was remedied on the DH Venom was that the aileron’s TE was extended back to form a tapered edge, like on a wing.
It would be interesting of Mr. Collins was some day able to find a set of Hornet ailerons in good to decent condition and compare them to the Mosquito, Vampire, and Venom ailerons as far as the trailing edges go.
By: ChernKStewfan - 8th January 2012 at 11:33
Well, I did my research after reading though the DH Hornet recollections section, and I found the info I wanted to discuss regarding the “Hornet vs Mosquito” aileron question. This was found in the recollections that John Wimpenny submitted about the design of the Hornet’s control surfaces, Wimpenny being an assistant to Eric Bishop during the Hornet’s design.
John said that the Hornet used ailerons that had had a blunt chord near the trailing edges and piano hinges (?) as opposed to the Mosquito’s set back hinges and more tapered trailing edges. This was an ideal that seemed to be good in theory for drag reduction, but in Wimpenny’s opinion, didn’t work out as well as planned because of inconsistencies in manufacturing. Each aileron ended up being slightly different to the other, with the result that if one was changed out, the aircraft’s handling and characteristics changed slightly as well depending on the aileron’s surface.
He also felt that the the DH Mosquito’s set back hinges allowed for more fluid and consistent feel to the pilots. But the issue he seemed to have was turbulence caused by the inconsistencies with the ailerons and that such items seemed to actually hinder the DH Hornet in the fight against compressibility, which likely reduced the roll rate and, at least to an extent, turning radius because of of the adverse effects that the ailerons had in their function.
It should be noted that the DH Vampire used similar ailerons without major issues until the last 20-30mph of it’s speed range, but with the DH Vampire, de Havilland not only introduced power-boosted controls, but reverted, at least partially, to the Mosquito set back hinges and tapered ailerons.
It seems that Wimpenny’s reservations about the Hornet seemed to be about the hinges and contours/taper of the ailerons and that, though a good idea in theory, didn’t bear the fruit with the Hornet that such changes did with say late Griffon-engined Spitfires, which the Spitfire had roll rate issues caused in part by compressibility which were largely cured by using a stronger wing torsion box (strengthened main and rear spars) and the new RAE ailerons. And in the case of the Hornet, due to the turbulence due to the inconsistent contours of the ailerons on the DH103, compressibility really reared it’s head and tended to reduce roll response dramatically, and probably didn’t do the Hornet’s turning performance any favors, either.
Power boosted controls helped solve the issue for the Venom, but so did “goin’ back to the future” by using what worked in the past with the Mosquito. Could the changes that Wimpenny be suggesting have resolved or at least remedied to an extent those issues he mentioned? That being said, knowing that, he was still impressed with how most of the pilots that flew it liked the Hornet. Maybe an instance of making a great plane even better?
Edit: @dcollins103: This post is actually what I was originally asking about. I wasn’t able to read your post prior to this one going up, as I was probably typing it while also trying to look up RAE’s name for the aileron type that Wimpenny used in his recollections submission. I will grant this that most of the Hornet’s pilots were former single engined fighter pilots (mostly having flown Mustangs, Spitfires and Tempests) who were quick to find fault relative to their former mounts–fighter pilots, like race drivers, after all, are never seemingly satisfied.
But the Hornet needed excellent agility to take on it’s intended foes of the Imperial Japanese Navy and IJAAF, and I’m willing to bet that in actual combat conditions that the Hornet likely, for it’s issues, could’ve likely held it’s own, but we’ll never know, because by V-J day, too few were in RAF hands to be sent out to the Pacific. And it must be remembered that most of these issues came to light in the fall of 1945 (in other words, post-war peace time) when an aircraft can be examined more thoroughly. And to test it against allied fighters (which were in general superior to most axis aircraft) can cloud the results, because an aircraft’s effectiveness relative to the enemy is what matters most.
I apologize for any confusion, but to get back to my original question, could the suggestions that Wimpenny made about the Hornet have changed anything and make a great aircraft even better?
And sorry for the long post–I only caught your message after I posted this originally.
By: ChernKStewfan - 8th January 2012 at 11:33
Well, I did my research after reading though the DH Hornet recollections section, and I found the info I wanted to discuss regarding the “Hornet vs Mosquito” aileron question. This was found in the recollections that John Wimpenny submitted about the design of the Hornet’s control surfaces, Wimpenny being an assistant to Eric Bishop during the Hornet’s design.
John said that the Hornet used ailerons that had had a blunt chord near the trailing edges and piano hinges (?) as opposed to the Mosquito’s set back hinges and more tapered trailing edges. This was an ideal that seemed to be good in theory for drag reduction, but in Wimpenny’s opinion, didn’t work out as well as planned because of inconsistencies in manufacturing. Each aileron ended up being slightly different to the other, with the result that if one was changed out, the aircraft’s handling and characteristics changed slightly as well depending on the aileron’s surface.
He also felt that the the DH Mosquito’s set back hinges allowed for more fluid and consistent feel to the pilots. But the issue he seemed to have was turbulence caused by the inconsistencies with the ailerons and that such items seemed to actually hinder the DH Hornet in the fight against compressibility, which likely reduced the roll rate and, at least to an extent, turning radius because of of the adverse effects that the ailerons had in their function.
It should be noted that the DH Vampire used similar ailerons without major issues until the last 20-30mph of it’s speed range, but with the DH Vampire, de Havilland not only introduced power-boosted controls, but reverted, at least partially, to the Mosquito set back hinges and tapered ailerons.
It seems that Wimpenny’s reservations about the Hornet seemed to be about the hinges and contours/taper of the ailerons and that, though a good idea in theory, didn’t bear the fruit with the Hornet that such changes did with say late Griffon-engined Spitfires, which the Spitfire had roll rate issues caused in part by compressibility which were largely cured by using a stronger wing torsion box (strengthened main and rear spars) and the new RAE ailerons. And in the case of the Hornet, due to the turbulence due to the inconsistent contours of the ailerons on the DH103, compressibility really reared it’s head and tended to reduce roll response dramatically, and probably didn’t do the Hornet’s turning performance any favors, either.
Power boosted controls helped solve the issue for the Venom, but so did “goin’ back to the future” by using what worked in the past with the Mosquito. Could the changes that Wimpenny be suggesting have resolved or at least remedied to an extent those issues he mentioned? That being said, knowing that, he was still impressed with how most of the pilots that flew it liked the Hornet. Maybe an instance of making a great plane even better?
Edit: @dcollins103: This post is actually what I was originally asking about. I wasn’t able to read your post prior to this one going up, as I was probably typing it while also trying to look up RAE’s name for the aileron type that Wimpenny used in his recollections submission. I will grant this that most of the Hornet’s pilots were former single engined fighter pilots (mostly having flown Mustangs, Spitfires and Tempests) who were quick to find fault relative to their former mounts–fighter pilots, like race drivers, after all, are never seemingly satisfied.
But the Hornet needed excellent agility to take on it’s intended foes of the Imperial Japanese Navy and IJAAF, and I’m willing to bet that in actual combat conditions that the Hornet likely, for it’s issues, could’ve likely held it’s own, but we’ll never know, because by V-J day, too few were in RAF hands to be sent out to the Pacific. And it must be remembered that most of these issues came to light in the fall of 1945 (in other words, post-war peace time) when an aircraft can be examined more thoroughly. And to test it against allied fighters (which were in general superior to most axis aircraft) can cloud the results, because an aircraft’s effectiveness relative to the enemy is what matters most.
I apologize for any confusion, but to get back to my original question, could the suggestions that Wimpenny made about the Hornet have changed anything and make a great aircraft even better?
And sorry for the long post–I only caught your message after I posted this originally.
By: TempestV - 8th January 2012 at 11:17
That can be an interesting point of discussion, because the P-38 and the P-61 had the engine nacelles extended to form the tail booms that retained the rudders and tail plane, which given what you’ve said, probably helped those aircraft in that respect, namely the P-38. And like the Hornet, the P-38 used handed engines.
If the engine nacelles caused some areo issues, other than extending them, was there much else that could be done?
And did this buffeting have anything to do with the seeming lack of agility that the Hornet had when it was tested after WWII, or is it simply a deal of it being a twin engined aircraft–after all, the P-38, especially late versions, could out turn and out roll Me-109s and FW-190s, in spite of the P-38 being larger and having a high wing loading. And the Hornet, of course, was about the same size and the same type of long range aircraft.
I think that I’m getting the gist that a lot of this might have to do with the Hornet having unforeseen compressibility issues, and if the P-38 had changes to it’s control surface hinges in addition to power boosting of major controls to battle comprehensibility, maybe answer lies in what could’ve been done to try and control the issue. I’ll try and brush up on the DH engineer’s comments on the aileron tech, and I’ll get back with a summary of his comments, but it seems that what he may’ve said may’ve been issues with compressibility.
Hi ChernKStewfan,
You seem to be drawing lots of comparisons between the Hornet and P38 in your postings. Apart from the fact that they were both twin engined long range escort fighters, the similarities end there.
The P38 used Allison engines, and all of the primary structure was aluminium. Its design was started in 1937, and first introduced in 1941, with over 7000 being made. It seems the P38 experienced a lot of compressibility problems in its protracted development, but had the resources of Lockheed and peacetime to develop it in. The twin boom layout of the P38 is likely to have accentuated its aero problems. The trade off between extending a nacelle to smooth airflow is that your skin area, and skin friction increases.
The Hornet by comparison, first flew in 1944, and entered service in mid 1946.
From what I have read and in discussion with former DH engineers, the Hornet’s design achieved most of what was intended for it. It was developed by a small team, during war time, and only had a projected production run of 1000, in which less that 400 were actually made. It was de Havillands second fighter design (the first being the Vampire) and it shared the same high speed aerofoil with the Vampire too. It is remarkable that its performance was so good, considering most of its primary structure was made in wood from dispersed “furniture factories” with final assembly only taking place at Hatfield, which was well within bombing distance of the Luftwaffe.
The aerodynamics on the Hornet were excellent, and it is only a minor point that one of these DH engineers commented that they could have made it even better given more time and resources. The fact is that when a design has radiators embedded in the leading edge of the wing, the air has to be exhausted somewhere. The best place to do this is on the underside of the wing, as the main spar would prevent you from ducting it further back. The minor down side of this is that the radiator exhaust flap would have the effect of making the airflow slightly turbulent. This was mostly overcome by clever radiator flap shape and extending the engine nacelle. The Hornet achieved its design targets of long range, climb rate, speeds at all heights, and manouvrability.
By: TempestV - 8th January 2012 at 11:17
That can be an interesting point of discussion, because the P-38 and the P-61 had the engine nacelles extended to form the tail booms that retained the rudders and tail plane, which given what you’ve said, probably helped those aircraft in that respect, namely the P-38. And like the Hornet, the P-38 used handed engines.
If the engine nacelles caused some areo issues, other than extending them, was there much else that could be done?
And did this buffeting have anything to do with the seeming lack of agility that the Hornet had when it was tested after WWII, or is it simply a deal of it being a twin engined aircraft–after all, the P-38, especially late versions, could out turn and out roll Me-109s and FW-190s, in spite of the P-38 being larger and having a high wing loading. And the Hornet, of course, was about the same size and the same type of long range aircraft.
I think that I’m getting the gist that a lot of this might have to do with the Hornet having unforeseen compressibility issues, and if the P-38 had changes to it’s control surface hinges in addition to power boosting of major controls to battle comprehensibility, maybe answer lies in what could’ve been done to try and control the issue. I’ll try and brush up on the DH engineer’s comments on the aileron tech, and I’ll get back with a summary of his comments, but it seems that what he may’ve said may’ve been issues with compressibility.
Hi ChernKStewfan,
You seem to be drawing lots of comparisons between the Hornet and P38 in your postings. Apart from the fact that they were both twin engined long range escort fighters, the similarities end there.
The P38 used Allison engines, and all of the primary structure was aluminium. Its design was started in 1937, and first introduced in 1941, with over 7000 being made. It seems the P38 experienced a lot of compressibility problems in its protracted development, but had the resources of Lockheed and peacetime to develop it in. The twin boom layout of the P38 is likely to have accentuated its aero problems. The trade off between extending a nacelle to smooth airflow is that your skin area, and skin friction increases.
The Hornet by comparison, first flew in 1944, and entered service in mid 1946.
From what I have read and in discussion with former DH engineers, the Hornet’s design achieved most of what was intended for it. It was developed by a small team, during war time, and only had a projected production run of 1000, in which less that 400 were actually made. It was de Havillands second fighter design (the first being the Vampire) and it shared the same high speed aerofoil with the Vampire too. It is remarkable that its performance was so good, considering most of its primary structure was made in wood from dispersed “furniture factories” with final assembly only taking place at Hatfield, which was well within bombing distance of the Luftwaffe.
The aerodynamics on the Hornet were excellent, and it is only a minor point that one of these DH engineers commented that they could have made it even better given more time and resources. The fact is that when a design has radiators embedded in the leading edge of the wing, the air has to be exhausted somewhere. The best place to do this is on the underside of the wing, as the main spar would prevent you from ducting it further back. The minor down side of this is that the radiator exhaust flap would have the effect of making the airflow slightly turbulent. This was mostly overcome by clever radiator flap shape and extending the engine nacelle. The Hornet achieved its design targets of long range, climb rate, speeds at all heights, and manouvrability.
By: john_txic - 8th January 2012 at 08:58
“Tempest” title looks interesting…. didn’t know about it.
Thanks!
By: john_txic - 8th January 2012 at 08:58
“Tempest” title looks interesting…. didn’t know about it.
Thanks!
By: MarkG - 7th January 2012 at 23:39
Hi John,
I’m not supposed to advertise on this forum, but if you send me a pm I can tell you all about this book.
I can’t see how it could be classed as advertising, especially compared to some of the blatant advertising that does go on around here.
Anyway, john_txic, it’s this book (4th one down) – http://www.dvpublishing.co.uk/content/content.php?page=1000.
By: MarkG - 7th January 2012 at 23:39
Hi John,
I’m not supposed to advertise on this forum, but if you send me a pm I can tell you all about this book.
I can’t see how it could be classed as advertising, especially compared to some of the blatant advertising that does go on around here.
Anyway, john_txic, it’s this book (4th one down) – http://www.dvpublishing.co.uk/content/content.php?page=1000.
By: ChernKStewfan - 7th January 2012 at 15:06
That can be an interesting point of discussion, because the P-38 and the P-61 had the engine nacelles extended to form the tail booms that retained the rudders and tail plane, which given what you’ve said, probably helped those aircraft in that respect, namely the P-38. And like the Hornet, the P-38 used handed engines.
If the engine nacelles caused some areo issues, other than extending them, was there much else that could be done?
And did this buffeting have anything to do with the seeming lack of agility that the Hornet had when it was tested after WWII, or is it simply a deal of it being a twin engined aircraft–after all, the P-38, especially late versions, could out turn and out roll Me-109s and FW-190s, in spite of the P-38 being larger and having a high wing loading. And the Hornet, of course, was about the same size and the same type of long range aircraft.
I think that I’m getting the gist that a lot of this might have to do with the Hornet having unforeseen compressibility issues, and if the P-38 had changes to it’s control surface hinges in addition to power boosting of major controls to battle comprehensibility, maybe answer lies in what could’ve been done to try and control the issue. I’ll try and brush up on the DH engineer’s comments on the aileron tech, and I’ll get back with a summary of his comments, but it seems that what he may’ve said may’ve been issues with compressibility.
By: ChernKStewfan - 7th January 2012 at 15:06
That can be an interesting point of discussion, because the P-38 and the P-61 had the engine nacelles extended to form the tail booms that retained the rudders and tail plane, which given what you’ve said, probably helped those aircraft in that respect, namely the P-38. And like the Hornet, the P-38 used handed engines.
If the engine nacelles caused some areo issues, other than extending them, was there much else that could be done?
And did this buffeting have anything to do with the seeming lack of agility that the Hornet had when it was tested after WWII, or is it simply a deal of it being a twin engined aircraft–after all, the P-38, especially late versions, could out turn and out roll Me-109s and FW-190s, in spite of the P-38 being larger and having a high wing loading. And the Hornet, of course, was about the same size and the same type of long range aircraft.
I think that I’m getting the gist that a lot of this might have to do with the Hornet having unforeseen compressibility issues, and if the P-38 had changes to it’s control surface hinges in addition to power boosting of major controls to battle comprehensibility, maybe answer lies in what could’ve been done to try and control the issue. I’ll try and brush up on the DH engineer’s comments on the aileron tech, and I’ll get back with a summary of his comments, but it seems that what he may’ve said may’ve been issues with compressibility.
By: TempestV - 7th January 2012 at 13:50
Which Hornet book is this, please?
Hi John,
I’m not supposed to advertise on this forum, but if you send me a pm I can tell you all about this book.
Hi ChernKStewfan,
Both the Mosquito and the Hornet experienced buffet around the rear of the engine nacelles, especially around the inboard flaps. Both aircraft ended up with a longer rear fairing on each engine nacelle accordingly, to try and reduce this buffet.
Also, it is difficult to compare the aerodynamics of these two aircraft directly as the opposite handed engine on the Hornet, really did change its overall flying characteristics.
Other details like the aileron hinges between jets and prop aircraft may also not be directly comparable, as the airflow over the jet airframe is much cleaner, and less stirred up by a prop wash.
By: TempestV - 7th January 2012 at 13:50
Which Hornet book is this, please?
Hi John,
I’m not supposed to advertise on this forum, but if you send me a pm I can tell you all about this book.
Hi ChernKStewfan,
Both the Mosquito and the Hornet experienced buffet around the rear of the engine nacelles, especially around the inboard flaps. Both aircraft ended up with a longer rear fairing on each engine nacelle accordingly, to try and reduce this buffet.
Also, it is difficult to compare the aerodynamics of these two aircraft directly as the opposite handed engine on the Hornet, really did change its overall flying characteristics.
Other details like the aileron hinges between jets and prop aircraft may also not be directly comparable, as the airflow over the jet airframe is much cleaner, and less stirred up by a prop wash.
By: ChernKStewfan - 7th January 2012 at 08:35
@pagen01: That could be part of the reason why the P-38 used powered ailerons, as they were fitted to a lot of -J and all -L and -M models, and they were the fastest of the Lightning family. However, almost all P-38s were fitted with dive recovery flaps (and on the Mosquito, the radiator outlet flaps could serve as such) to prevent that, and I read online, trying to find the info that David had lead me to, that the powered ailerons also helped give the later P-38s a noted reduction in turning radius, and, above all, a massively improved roll rate.
@dcollins103: If I remember correctly, the issues with the hinges were part function and feel, and part aerodynamic. The Vampire used the type of hinge that the Hornet used, and it worked as hoped. The RAF endorsed the use of that hinge to reduce drag as it didn’t protrude on the upper surface of the wing. But the Vampire had an all-metal wing, as did the P-38. However, the Hornet’s wing was part metal (wing main spars, some stringers and ribs, and underside skin), and wood (parts of the main spars, upper skin, and some stringers/ribs). It seems that the metal Vampire wing was more receptive to the RAF’s hinge than the Hornet’s mixed construction wing.
On the aero side of the equation, the protruding (but well faired) Mosquito hinge did likely cause a marginal amount of drag, but probably not enough to make a huge difference (probably less than the Sea Hornet’s wing fold hinges, which likely wasn’t much, either). I do remember, possibly rightfully or wrongfully, that there was an airflow issue over the ailerons that caused issues with buffeting/turbulence that hindered their effectiveness. This may’ve been fixed at a later stage, but we must also remember that most Hornet pilots trained on Mosquitoes (as most Hornet pilots were former Spitfire, Mustang, or Tempest pilots), and I do seem to remember from the book that one pilot did remark that the ailerons did feel different on the stick, and that the Mosquitoes did feel better as far as ease of use and harmony.
I do wonder if that wing/radiator outlet issue played a bigger role in the Hornet’s handling/maneuverability issues, especially early in it’s life, than the aileron issues mentioned. Did the Mosquito have this issue? If not, then it could be a design issue, as both the Hornet and Mosquito radiators did use the zero drag/Meredith effect to generate thrust to offset any cooling drag, and it seems that the Hornet’s radiator fairings extended back further relative to those of the Mosquito, ironically because the Hornet’s radiators had to handle more cooling, as water, oil, and supercharger intercooler were cooled by one main matrix per wing.
Of course, such a thing is of an academic interest now, as this was never fully cured in the Hornet’s decade long RAF career, and with the Vampire and Meteor becoming the RAF’s main fighter element, the Hornet’s issues were of secondary importance, though if the war against Japan wore on, it would’ve become a major importance.
And one more question: In the British Fighter since 1912, the Hornet was quoted as having a roll-rate of 72 degrees per second (highest recorded by a twin-engined piston fighter), though this was most likely achieved by either a prototype, or an early production aircraft partially loaded. For comparison, the Martin Baker MB5 had a roll-rate of 94 deg/second, one of the highest figures for any piston engined fighter. Could this simply be a thing of production aircraft usually being heavier that certain measures didn’t fully compensate for that scenario?
@john txic: DH Hornet and Sea Hornet: de Havilland’s Ultimate Piston-Engined Fighter, co authored by Mr. Collins, of course :). Great source of info and rare photos and technical details.
By: ChernKStewfan - 7th January 2012 at 08:35
@pagen01: That could be part of the reason why the P-38 used powered ailerons, as they were fitted to a lot of -J and all -L and -M models, and they were the fastest of the Lightning family. However, almost all P-38s were fitted with dive recovery flaps (and on the Mosquito, the radiator outlet flaps could serve as such) to prevent that, and I read online, trying to find the info that David had lead me to, that the powered ailerons also helped give the later P-38s a noted reduction in turning radius, and, above all, a massively improved roll rate.
@dcollins103: If I remember correctly, the issues with the hinges were part function and feel, and part aerodynamic. The Vampire used the type of hinge that the Hornet used, and it worked as hoped. The RAF endorsed the use of that hinge to reduce drag as it didn’t protrude on the upper surface of the wing. But the Vampire had an all-metal wing, as did the P-38. However, the Hornet’s wing was part metal (wing main spars, some stringers and ribs, and underside skin), and wood (parts of the main spars, upper skin, and some stringers/ribs). It seems that the metal Vampire wing was more receptive to the RAF’s hinge than the Hornet’s mixed construction wing.
On the aero side of the equation, the protruding (but well faired) Mosquito hinge did likely cause a marginal amount of drag, but probably not enough to make a huge difference (probably less than the Sea Hornet’s wing fold hinges, which likely wasn’t much, either). I do remember, possibly rightfully or wrongfully, that there was an airflow issue over the ailerons that caused issues with buffeting/turbulence that hindered their effectiveness. This may’ve been fixed at a later stage, but we must also remember that most Hornet pilots trained on Mosquitoes (as most Hornet pilots were former Spitfire, Mustang, or Tempest pilots), and I do seem to remember from the book that one pilot did remark that the ailerons did feel different on the stick, and that the Mosquitoes did feel better as far as ease of use and harmony.
I do wonder if that wing/radiator outlet issue played a bigger role in the Hornet’s handling/maneuverability issues, especially early in it’s life, than the aileron issues mentioned. Did the Mosquito have this issue? If not, then it could be a design issue, as both the Hornet and Mosquito radiators did use the zero drag/Meredith effect to generate thrust to offset any cooling drag, and it seems that the Hornet’s radiator fairings extended back further relative to those of the Mosquito, ironically because the Hornet’s radiators had to handle more cooling, as water, oil, and supercharger intercooler were cooled by one main matrix per wing.
Of course, such a thing is of an academic interest now, as this was never fully cured in the Hornet’s decade long RAF career, and with the Vampire and Meteor becoming the RAF’s main fighter element, the Hornet’s issues were of secondary importance, though if the war against Japan wore on, it would’ve become a major importance.
And one more question: In the British Fighter since 1912, the Hornet was quoted as having a roll-rate of 72 degrees per second (highest recorded by a twin-engined piston fighter), though this was most likely achieved by either a prototype, or an early production aircraft partially loaded. For comparison, the Martin Baker MB5 had a roll-rate of 94 deg/second, one of the highest figures for any piston engined fighter. Could this simply be a thing of production aircraft usually being heavier that certain measures didn’t fully compensate for that scenario?
@john txic: DH Hornet and Sea Hornet: de Havilland’s Ultimate Piston-Engined Fighter, co authored by Mr. Collins, of course :). Great source of info and rare photos and technical details.
By: john_txic - 7th January 2012 at 08:33
Which Hornet book is this, please?
By: john_txic - 7th January 2012 at 08:33
Which Hornet book is this, please?
By: TempestV - 6th January 2012 at 15:59
Hi ChernKStewfan,
The Hornet aerodynamic issues were mostly resolved, but as with the other few prop-driven aircraft that were pushing the achievable speeds to the limits a few issues still remained, that could have been resolved given more development time.
The specific aerodynamic issue that was never fully resolved was the partially turbulent airflow between the engine nacelle and fuselage, from the lower lip of the radiator flap and the main wing flap itself. No aircraft design is perfect, and merely the best comprimise to achieve the goals for the type.
If you look at the evolution of the DH twin engined wooden tail-dragger “family” The Hornet had better aerodynamics than the Mosquito, and the Mosquito had better aerodynamincs than the Comet racer, so it can be seen as an improvement/evolution on those particular types.
Comparing the Lockheed Lightning and de Havilland Hornet is an interesting study that could be made. They were both concieved as long range escort fighters, but executed in different ways, using different materials. There are outstanding features on both, but neither is the perfect flying machine.
By: TempestV - 6th January 2012 at 15:59
Hi ChernKStewfan,
The Hornet aerodynamic issues were mostly resolved, but as with the other few prop-driven aircraft that were pushing the achievable speeds to the limits a few issues still remained, that could have been resolved given more development time.
The specific aerodynamic issue that was never fully resolved was the partially turbulent airflow between the engine nacelle and fuselage, from the lower lip of the radiator flap and the main wing flap itself. No aircraft design is perfect, and merely the best comprimise to achieve the goals for the type.
If you look at the evolution of the DH twin engined wooden tail-dragger “family” The Hornet had better aerodynamics than the Mosquito, and the Mosquito had better aerodynamincs than the Comet racer, so it can be seen as an improvement/evolution on those particular types.
Comparing the Lockheed Lightning and de Havilland Hornet is an interesting study that could be made. They were both concieved as long range escort fighters, but executed in different ways, using different materials. There are outstanding features on both, but neither is the perfect flying machine.
By: pagen01 - 6th January 2012 at 15:53
Re powered controls, I’ve been doing a little research into early de Havilland high speed flight lately and one thing that it has unearthered is that the use of powered ailerons (followed by other control surfaces) was driven more by high speed flight than by simply giving increased controllability, or pilots ease of use, on conventional aircraft.
Powered controls allowed for better controlled transonic/supersonic flight as they were irreversible, ie the aerodynamic forces over the ailerons could not overwhelm the hydraulics/mechanics of a powered system, like they could with the conventional mechanical cable and pulley systems which could then experience flutter and incorrect control movements.
What I’m trying to say was that there was little perceived need in the UK for powered systems on a conventional structure and performance aircraft at the time.
DH introduced powered ailerons with the DH.108 & 110, which were of course transonic and just supersonic, the DH.112 Venom came later of and had them fitted.
I know very little about the Hornet or P-38 Lightning, but I wonder if the Lightning had powered ailerons because it could encounter compressibility near the transonic regime in a dive?
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January 6, 2012 at 10:54 am