Kurfürst

Avgas octane / performance rating was generally not an issue for German/French/Russian engines since they had generous swept volumes and compression ratios, and could achieve high outputs at lower boosts and/or extreme supercharging, therefore not really require fuels with high performance rating. The 87 octane B-4 in itself was enough for about 1,5 ata, or perhaps even more when used with lower compression ratios. Its also not a coincidence that that while C-3 had excellent rich performance rating of around 140-150, the chemist were satisfied with a 96 octane lean performance rating.

It's a good choice IMO, everybody simply gets the 2nd half of 1944 stuff, not the my-late-war-plane-is-überst stuff. Gonna freak some people out, though.

Good suggestion - I heartily invite Friedrich to share his many findings on the 109's nuts and bolts and bits on my own discussion board instead (http://kurfurst.freeforums.org/index.php). He seems to be very fond of discussing aircraft to such depth and I am sure he will find a sympathizing audience there; here some may find this, however much we enjoy it, well, just utterly taxing. Its also a more proper venue for such, this is a simulation board after all and should be, first and foremost, a forum for discussing the DCS sim environment.

Yes, those systems were already present as added weight, as given above. Intercoolers and two stage supercharger system were necessary for the Merlin/Griffon series, since those relied heavily on rather high boost pressures to produce power. MW 50 essentially produced the same effect of charge cooling, just with different methods.

Not the only, by far. There was the weight and drag of the inter cooler system, enlarged radiators to cope with the heat generated and the weight and bulk of two stage superchargers to actually produce the pressure required to make any advantage of the higher anti-detonation rating of higher grade fuels. These systems in effect were responsible for the same thing as MW-50 - cooling the charge and the engine itself. Installing all this resulted in a weight creep from about 6600 lbs of the Mark V Spitfires to 7400 lbs on the Mark IX Spitfires.

Curiously, aileron Flettners appear to be mostly fitted to WNF built G-6s, G-14s and G-10s. Could be a factory specific thing, though Flettners were definietely meant for Ks, as per manual.

Soviet trial results of Spitfire Mk IXLF. The Soviet Union received 1000+ Spitfire IXs during the war and were used for home defense duties in rear. Top speed was found to be 528 km/h at SL, 628 km/h at 5500, top climb rate 22,8 m/sec - quite impressive.

On the related note, how does DCS model the maximum physical főre the pilot can Apple to the stick?

From : "Measurements of the flying qualities of a Supermarine Sptitife VA airplane." NACA Advanced Confidental Report, by William H. Phillips and Joseph R. Vensel. The tests were conducted at Langley field, Va., during the period from December 30, 1941 to January 29, 1942. Sixteen flights and apprx. 18 hours flying time were required to complete the tests. [...] Desription of the the Supermarine Spitfire airplane Name and Type : Supermarine Spitfire VA (Air Mininstry No. W3119). Engine : R-R Merlin XLV Weight, empty : 4960 lbs Normal gross weight : 6237 lbs Weight as flown for tests : 6184 lbs Ailerons (metal-covered) Lenght (each) : 6 feet, 10 1/2 inches Area (total area, each) : 9.45 sq. feet Balance area (each) : 2.45 square feet [...] A stick force of 2 lbs to the right and 3 lbs to the left was required to overcome aileron friction. [...] Lateral Stability and Control Aileron-control characteristics : The effectiveness of the ailerons of the Supermarine Spitfire airplane was determined by recording the rolling velocity produced by abrubtly deflecting the ailerons at various speeds. The aileron angles and stick forces were measured. It should be noted that the airplane tested was equipeed with metal covered ailerons. [...] The ailerons were sufficiently effective at low speeds, and were relatively light at small deflections in high speed flight. The forces required to obtain high rolling velocities in high-speed flight were considered excessive. With a stick force of 30 lbs, full deflection of the ailerons could be obtained at speeds lower than 110 miles per hour. A value of pb/2V of 0.09 radian in left rolls and 0.08 radian in right rolls were obtained with full deflection. Rolling velocity (at 6000 ft altitude) of about 59 degrees per second could be obtained with 30 lbs stick force at 230 miles per hour indicated speed. The ailerons were relatively light for small deflections, but the slope of the curve of stick force against deflection increased progressively with deflection, so that about five times as much force was required to fully deflect the ailerons as was needed to reach one-half of the maximum travel. The effectiveness of the ailerons increased almost linearly with deflection all the way up to maximum position. The value of pb/2V obtained for a given ailerons deflection was nearly the same in speeds and conditions tested. It may be concluded, therefore, that there was very little reduction in aileron effectiveness either by separation of flow near minimum speeds or by wing twist at high speed. Fig 27 shows the aileron deflection, stick force, and helix angle obtained in a series of roll at various speeds intended to represent the maximum rolling velocity that could be readily obtained. The pilot was able to exert a maximum of about 40 lbs on the stick. With this force, full deflection could be attained only up to about 130 miles per hour. Beyond this speed, the rapid increase in stick force near maximum deflection prevented full motion of the control stick. Only one-half of the available deflection was reached with a 40 lbs stick force at 300 miles per hour, with the result that the pb/2V obtainable at this speed was reduced to 0.04 radian, or one-half that reached at low speeds. Another method of presenting the results of the aileron-roll measurements is that given in figure 28, where the force for different rolling velocities is plotted as a function of speed. The relatively light forces required to reach small rolling velocities are readily seen from this figure. The excessive forces required to reach high rolling velocities and the impossibility of obtaining maximum aileron deflection much above 140 miles per hour are also illustrated. From : STABILITY AND CONTROL SUB-COMMITEE. AERONAUTICAL RESEARCH COMMITEE Comparision of aileron control charactheristics as determined in Flight Tests of P-36, P-40, 'Spitfire' and 'Hurricane' Pursuit airplanes. By William H. Philps. N.A.C.A. Confidental Bulletin. 16th November, 1942 [..] The aileron effectiveness of the various airplanes is compared in the following table on the basis of the response obtained with stick forces of 30 and 5 pounds. A force of 30 lbs is somewhat less than the greatest stick force exerted by the pilot. Repeated flight measurements have shown, however, that this forcer is a reasonable upper limit for manouvering at high speeds. A comparision at a stick force of 5 lbs are also included to bring out a rather interesting fact regarding the order of merit of aileron effectiveness for the various airplanes when very light forces are used : Rolling velocities obtained with 30 lbs stick force at 230 mph indicated airspeed at 10 000 ft. (deg/sec) P-36 : 43 P-40 : 90 Hurricane : 64 Spitfire : 63 Rolling velocities obtained with 5 lbs stick force at 230 mph indicated airspeed at 10 000 ft (deg/sec) P-36 : 9 P-40 : 8 Hurricane : 19 Spitfire : 15 A further comparision of the aileron performance of the four airplanes is given in figure 2, which shows how the control force characteristics influence the rolling velocities obtained through the speed range." Full report at: http://jsbsim.sourceforge.net/spit_flying.pdf

It may be possible to borrow one from Prince Harry... :D

You need to read the discussion before commenting on it- the statement that is extremely wrong is that C-3 was only arrived with Fw 190As. In contrast the historical fact is that C-3 was available was already available at the start of the war, if not before. In fact one of driving factors behind the British seeking American import of 100 octane avgas was that while the British had to import it, the Germans were making as much as they wanted from scratch, or rather, coal, through the industrial scale synthetic processes and plants. It is also fundamentally wrong that its large scale introduction was tied with the Fw 190. The fact is the that large scale introduction was in 1940/41 with the DB 601N powered 109s and 110s, well before the Fw 190. Note also that the fact initial Fw 190 models relied on B-4... That's very much a valid point but then again, even He 111 units in late 1944 were relying on C-3, too. Alongside C-3. In fact, during the late war period C-3 was estimated to be the majority of synthetic production. It should be kept in mind that since aviation fuel in German was practically all-synthetically produced and C-3 was basically just further produced B-4.

You extremely wrong in this. C-3 was in fact the premiere fighter fuel as early as 1941, see strenght report of June 1941. http://ww2.dk/oob/statistics/se28641.htm There are no less than 782+ Bf 109s (E/N, T, F-1, F-2 types) listed there running on C-3, having the DB 601N engine. Others may, too, since from the start of 1941 all 109E and F were produced with the DB 601N that used C-3. That's quite feasible too. We need to remember that C-3 just a standard LW fuel type that was preferred to be used for engine operation at higher boost after MW boost was introduced. Using C-3 with methanol never stopped, in fact several manuals ie. G-14's MW instruction manual from October 1944 also mentions it that 150 grade C-3 should be used with MW boost; using B-4 is also possible but its more risky since if the MW system fails, B-4 does not have the required anti-detonation qualities to suppress detonation and such case, engine damage will occur.

I am not sure what the point is - but the usage of 150 grade C-3 type fuel indeed pre-dates the clearance for the DC engine, i.e. it was a standard fuel used by the Luftwaffe in large quantities since 1939/40. The 10 minute duration is also mentioned in the earliest 109K manuals, there is no change in that. It appears this was standard duration for methanol boost conditions. Earliest example of methanol and C-3 being used in combination since March / April 1944 on early methanol boosted G-5/AS. The practically had the same performance as the G-10 and being only a bit slower than the 109K. C-3 and MW 50 was already used by K-4/G-10 before March 1945 as well, but the greater boost pressure (ie. more power) was not allowed yet.

Further on the clipping of Spitfire wings. Apparently the modification was beneficial to those production machines which had a "poor set of ailerons" and at the same time, little improvement was observed on machines with good set of ailerons. The application of sensitive Frise type ailerons used also on the Spitfire may have also contributed, as this type was sensitive for correct balancing and pairing. The clipping of the wings was therefore not recommended, apart from fixing structural issues observed with the Spitfire during maneuvers involving diving. Clipping was probably done to reduce wing twisting reducing roll rate...

Special emergency power C-3 + MW was cleared for 10 minutes of duration, i.e. for a longer period than usual. Between two ten minute (!!) uses a 5 minute cooldown period was recommended. The MW booster carried in the plane was sufficient for 26 minutes of continuous Special Emergency use.

The trouble was not with the engine per se. Development wise, it was fine and did not need modifications. The root of the problem was that in around December 1944 there was an assembly problem at DB's factory. Some 70 engines failed because of two reasons a) being that the valves were not properly secured during installation (i.e. being loose) and b) one of the sub-contractors (IIRC Henschel) was supplying very slightly larger diameter cylinder heads, which caused them to stuck. Hence the reoccurring damage to the pistons and connecting rods... DB already noted and fixed that by December 1944 by properly instructing the assembly personel and ordering proper sized cylinders. They reassemled the failed engines in the proper way and they run fine w/o problems. But RLM wanted to be on the safe side and to perform tests in Rechlin (Ju 52 testbed) and in the field (with II./JG 11 near Berlin with G-10, G-14/ASC and K-4, ie. ASC/DC engines). Both were successful with no particular problems and by early March 1945 and clearance for use has been granted for four Wings (two of JG 27 and 53 each) on the Western front. One unrelated problem to Daimler Benz was that B-4 (i.e. low 87 octane for the 605DB at 1.8ata) fuel quality tended to variate towards the war's end, and not trending towards being better. With sub par fuel not meetiong the specs, white flames could be observed in the exhaust and subsequent engine damage (605 DB configuration only). While various blending methods incl. the use of anilin additive was used to rectify the problem, they kept on the safe side and solved the problem by delayed ignition on the 1.8ata 605DB and also that MW injection would kick in sooner, at lower manifold pressures (1.4ata already instead of 1.45ata). The instructions were given out in March 1945. The DC engine had no such ignition problems because the 150 grade C-3 fuel remained available for use in compromised quality and therefore no modification to the engine was necessary. Its BTW important to note that the only difference between the DB and DC is their settings - the DC had different fuel injection pump and manifold pressure settings (1.98 ata).

GGS Gyro gunsight was not regularly fitted to Spitfire aircraft even in March - April 1945: See "Was Gyro gunsight used - No, Not Fitted." There are a few exaples of the sight being fitted towards the end of April 1945, a few weeks before the war's end. http://www.wwiiaircraftperformance.org/130_Samouelle_24april45.jpg

Yes I agree, its just an interesting tidbit about future development plans. I don't think the 2.3 ata rating was introduced before the end of the war, as testing has been reported to have just begun in January 1945. It shows the potential though. By March-April 1945, it was already decided that piston engined fighters would be gradually withdrawn (a which was over zealously carried out in May by pouring gasoline on aircraft ;)

Its being reported by the last page of DB memo 6730 in January 1945 - available in full at: http://kurfurst.org/Engine/Boostclearances/DB_Niederschrift6730_DB605DBDC_20-1-45.pdf

The DB 605 DC of the G-10/K-4 was being developed to 2.3 ata, i.e. ca 2300 PS output :

Conclusion from the report "Note on the Speed of Production Spitfires". It is concluded that there were some increase in drag from added external equipment, bumps, cannon barrels and the like, and furthermore the production quality was so low at a point that serial production Mk Vs (as opposed to shiny prototypes) could not even reach the top speed of the previous Mk I. The Mark IX saw "some improvement" in the poor quality of surface finish.

Range of Spitfire IX (M 61)

RAAF testing with serial production Mk VIII JF 934.

Dive instructions for the Spitfire II, warning of airframe failures due to control characteristics (because of very light elevator controls, it is easy to overstrain the airframe, even accidentally)

'All care' should be excercised when using the metal covered ailerons in high speed dives because of the 'great strain imposed' on the Spitfire: