DO-335 VS TA-152

[HoHun]

Hi Erich,

>the Do and the Ta cannot even be fairly compared

For a fair comparison of the airframes, you'd have to eliminate the engine from the equation.

Equipped with the Jumo 213E installed in the Focke-Wulf Ta 152H, which was considerably more powerful than the DB 603A which drove the early Dornier Do 335, the type could have achieved top speeds of 800 km/h or better.

The Do 335 might not have made a great dogfighter, but it sure was fast.

Regards,

Henning (HoHun)

[Soren]

Still it wasn't fast enough. The Me-262 was allot faster, lighter and carried a more powerful armament.

The Do-335 is an impressive piston engined a/c, no doubt, but another a/c [Me262] already filled out its intended role far more efficiently than the Do-335 could ever hope to do.

The future was coming with the Me-262.

As for comparing the Do-335 with the Ta-152H, well they were two different types of aircraft intended for two different roles. However they both resembled the pinnacle of piston engined aircraft design.

[red admiral]

The Do-335 suffered from cooling problems with the rear engine when running at high powers. The engine would overheat so the rear exhaust flaps had to be opened, which would cause the aircraft to porpoise at high speed. The problems would most likely have been solved with time, but time wasn't available. The Me-262 was probably better for the application anyway.

Compared to the similar sized d.H. Hornet, the Do-335 arrangement doesn't seem to offer a great many advantages for the problems it caused.

[davparlr]

In order to assess the effectiveness of these two aircraft, we need to examine their capability against allied aircraft, not including jets, they would have met in the summer of 1945, the P-51H, and P-47M, and let’s throw in the F4U-4 for fun. Aircraft are listed from best to worst.

Wing Loading, Gross (lbs/wing area)
F4U-4 39.6
P-51H 40.4
Ta-152H 41.7
P-47M 43.1
Do-335 51.0

Power Loading,Gross-SL (wt/hp)
P-51H 4.3
F4U-4 5.06
P-47M 5.1
Ta-152H 5.1
Do-335 5.8

Power Loading-25k
P-47M 4.74
P-51H 5.94
F4U-4 6.9
Ta-152H 7.48
Do-335 unk

Power loading-30k
P-47M 4.74
P-51H 7.11
F4U-4 7.3
Ta-152H 7.8
Do-335 ukn

Airspeed-SL (mph)
P-51H 410 mph
F4U-4 374
Ta-152H 370
P-47M 365
Do-335 ukn

Airspeed 25k
Do-335 474 (at 21k)
P-51H 466
P-47M 453
Ta -152 449
F4U-4 448

Airspeed 30k
P-47M 467
Ta-152H 463
P-51H 448
F4U-4 442
Do-335 unk

Rate of climb, SL (ft/min)
P-51H 4600
P-47M 4000
F4U-4 3600 (at mil rated power, not WEP)
Ta-152H 3445 (only data I’ve seen)
Do-335 2165

Rate of climb, 25k
Ta-152 unk, 2854 at 29k
P-47M 3000
F4U-4 2700 at mil power, not WEP
P-51H 2350
Do-335 unk

Ceiling (ft.)
Ta-152H 49540
P-41H 41600
F4U-4 41600
P-47M 41000
Do-335 37400

Of course, this doesn’t show all the comparison and some I don’t have, especially with the Do-335 and its DB-603E engine. But we can come up with some trends. One, the Do-335 is very heavy, with a loaded weight of 21,120 lbs (about the weight of the A-20 attack bomber) and this shows up in its poor power loading and wing loading. This also appears to impact its rate of climb and time to climb (I only had time-to-climb for the V-1 version which has a slightly less powerful engine. Time to climb to 26k was 14.5 min compared to the 7 min for the P-51H). Also, its ceiling was the lowest of the bunch. It is very fast at 21k ft make 474 mph, but not far off from the P-51H which most likely has quite a superior climb and power loading. This airspeed difference (less than 10 mph) is not enough to make an overpowering aircraft, as the speed advantage of the Me-262 did.

The power curve for the P-47M is amazing with basically a level 2800 hp from10k to 33k+, which shows up on its impressive power loading.

Below 25k ft., both the P-51H and F4U-4 would be formidable opposition to both the Do-335 and Ta-152H. The P-47M really comes into its own from 25k to about 33k due to its large power loading advantage. At around 30k rate of climb drops off.

Ta-152H would pretty well contest the airspace above 25k and dominate above 30k.

There was no need for the Do-335. It did not add enough performance to warrant development. Time, money and energy would have been better spent on the Ta-152H, or better yet all effort should have been on building the Me-262 as a fighter in ’44. Now that would have made a difference.

[Soren]

Davparlr,

As has often been stated the 3,444 ft/min climb rate was achieved when running at Steig u. Kampfleistung. At SonderNotleistung the Ta-152H's climb rate is over 5,000 ft/min atleast, and with the Jumo 213 EB which was ready by wars end this would've increased even further.

The top SL speed varied from 585 - 597 km/h, while top speed at alt was 760+ km/h.

Furthermore the wingloading figures are as we both know useless really, esp. considering the many differences in wing & airfoil designs between these aircraft.

The Ta-152H benefitted from using a very high lift airfoil (NACA 23000 series) whilst it also featured a very high AR wing design, increasing lift even further whilst significantly decreasing drag, esp. in maneuvers.

The Do-335 featured the same NACA 23000 airfoil, however it was a VERY thick airfoil (Root: 23018 Tip: 23012), which means a higher amount of lift, however the AR of the wing wasn't very high, increasing drag in maneuvers.

Do-335
Wing span: 13.8 m
Wing area: 38.5 m^2
Wing AR: 4.94
Empty weight: 7,260 kg
Loaded weight: 8,590 kg
Max loaded weight: 9,600 kg

[AVRoe]

I have to look in to this at work(dornier)

[HoHun]

Hi Davparlr,

>Airspeed 25k
>Do-335 474 (at 21k)
>P-51H 466
>P-47M 453
>Ta -152 449
>F4U-4 448

Good approach to use speeds at identical altitude!

That the Do 335 reaches its top speed below 25000 ft, yet is the fastest in the group shows its main strength: Straight-line speed. With the engine of the Ta 152H, it could - according to my peronsal estimate - probably have reached 500 mph at about 25000 ft, and about the same speed at 36000 ft. (Being slower in between.)

Note that the advantage of the Do 335 over the Ta 152H is greater at 25000 ft than at 36000 ft due to the small wing of the Do 335. It would have benefitted from a larger wing, and I seem to remember reading about plans to implement one.

>There was no need for the Do-335. It did not add enough performance to warrant development.

The Do 335's primary strength was straight-line speed, and it could have exceeded the Allied propeller fighters' performance by a fair margin in that regard. It would not have matched their climb or turn rate. The Do 335 took second place to the jet fighter, but if jet technology had met an unexpected obstacle, the Do 335 would still have meant a technological advantage for the Luftwaffe, albeit of reduced magnitude.

One thing to keep in mind is that early jet engines were not that powerful at high altitude, and accordinlgy, a large-wing Do 335 variant might have been a better interceptor for high-flying B-29 bombers than a Me 262.

Just to show the factors that might have played a role in the development of the Do 335 - it might not have been needed in the "scenario" that unfolded historically, but if history had taken a slightly different road than the one we're familiar with, the Do 335 might have turned out to be a very useful development after all.

Regards,

Henning (HoHun)

[Soren]

Hohun,

You're right about a larger/longer wing being planned for the Do-335, the AR being increased, and with the Jumo 213 EB this would've amde for a very potent high alt bomber interceptor. Armed with two Mk-103's it would've layed waste to the bombers from ranges where they had no hope of firing back.

You can see the planned development on this drawing:

[davparlr]

Originally Posted by HoHun

Hi Davparlr,

>Airspeed 25k
>Do-335 474 (at 21k)
>P-51H 466
>P-47M 453
>Ta -152 449
>F4U-4 448

Good approach to use speeds at identical altitude!

That the Do 335 reaches its top speed below 25000 ft, yet is the fastest in the group shows its main strength: Straight-line speed. With the engine of the Ta 152H, it could - according to my peronsal estimate - probably have reached 500 mph at about 25000 ft, and about the same speed at 36000 ft. (Being slower in between.)

I am not sure as I do not have any data on the DB 603E and its supercharger implementation. The low ceiling, however, tends to imply that the aircraft is more tuned to lower altitude performance (25k and below). As for 500 mph, I think that the piston powered aircraft was pretty well reaching its perfomance limit in speed and several aircraft claimed to have flown 500 mph, all of which I am skeptical of, if nothing more than lack of proper instrumentation. The XP-72, with 3000 hp at 25k, was claimed have achieved 500 mph but apparently the pilot denied it. I believe him. It apparently did go 480-490 mph, which I have some skepticism about, but it did have 3000 hp and the P-47 airframe was proven to be fast. By the time the Do-335 began flying, the XP-72 had been cancelled due to changing need for a escort fighter and not an interceptor, and most likely the promised performance of the upcoming jets. It is interesting to note that the engine in the XP-72, while at the time the most powerful piston engine in WWII, eventually obtained over 4000 hp in later years.

The Do 335's primary strength was straight-line speed, and it could have exceeded the Allied propeller fighters' performance by a fair margin in that regard. It would not have matched their climb or turn rate. The Do 335 took second place to the jet fighter, but if jet technology had met an unexpected obstacle, the Do 335 would still have meant a technological advantage for the Luftwaffe, albeit of reduced magnitude.

True, I did not think of this.

[HoHun]

Hi Davparlr,

>I am not sure as I do not have any data on the DB 603E and its supercharger implementation. The low ceiling, however, tends to imply that the aircraft is more tuned to lower altitude performance (25k and below).

The aerodynamical advantage of the Do 335 is evident from the height differential for roughly equal top speed since at low altitude, it is handicapped by the greater drag of the denser air. If you look at speed over altitude diagrams of WW2 fighters, speed invariably increases with altitude until the full through height of the engine is reached. (Since many engines had two supercharger speeds, they had two full-throttle heights, giving the familiar "sawtooth" look of so many curves.)

In short, if you provide the Do 335 with an engine of equal power but greater full throttle height that matches those of the fighters it's compared against, it will be faster than it was at 21000 ft, where it was as fast in terms of true airspeed as the others at 25000 ft.

(The low ceiling you observed is caused not only by the engine characteristics, but also by the relatively small wing.)

>As for 500 mph, I think that the piston powered aircraft was pretty well reaching its perfomance limit in speed and several aircraft claimed to have flown 500 mph, all of which I am skeptical of, if nothing more than lack of proper instrumentation.

I absolutely agree on the value of caution. In fact, I'd have been disappointed if the 500 mph figure I suggested would not have been met with skepticism

All I can say is that I have calculated it carefully, and don't mean it to be the final word on the type anyway. I just thought quoting an actual figure I personally consider realistic would be better than simply writing "It would have been very, very fast"

>By the time the Do-335 began flying, the XP-72 had been cancelled due to changing need for a escort fighter and not an interceptor, and most likely the promised performance of the upcoming jets.

Quite right - in fact, there was some disappointment among Luftwaffe officers assigned to the secret Do 335 project when they learned it was not going to be a jet aircraft. The technological landslide is also evident from some later Do 335 spin-off paper projects that showed the rear engine being replaced by a turbojet, a configuration which resembles the later (and actually built) Ryan Fireball fighter.

Regards,

Henning (HoHun)

[davparlr]

Originally Posted by HoHun

Hi Davparlr,

>
The aerodynamical advantage of the Do 335 is evident from the height differential for roughly equal top speed since at low altitude, it is handicapped by the greater drag of the denser air. If you look at speed over altitude diagrams of WW2 fighters, speed invariably increases with altitude until the full through height of the engine is reached. (Since many engines had two supercharger speeds, they had two full-throttle heights, giving the familiar "sawtooth" look of so many curves.)

No doubt that the D0-335 was the cleanest of all two engine designs (except possibly one with a counterrotating prop, but I don't know any designs that uses that combination. Several single engine planes tried it, but it was complex).

In short, if you provide the Do 335 with an engine of equal power but greater full throttle height that matches those of the fighters it's compared against, it will be faster than it was at 21000 ft, where it was as fast in terms of true airspeed as the others at 25000 ft.

I just have no idea of the thrust profile of the engine. Also, It would have been nice to have a SL top speed.

All I can say is that I have calculated it carefully, and don't mean it to be the final word on the type anyway. I just thought quoting an actual figure I personally consider realistic would be better than simply writing "It would have been very, very fast"

No doubt about this. It should have been very fast.

[Zarathos]

Also, It would have been nice to have a SL top speed.

SL - sea level? If yes, then its 580 km/h (360 mph).

[davparlr]

Originally Posted by Zarathos

SL - sea level? If yes, then its 580 km/h (360 mph).

Is your data good? Is it the last version, I think, the A? 360 mph is the slowest of the bunch:

Airspeed-SL (mph)
P-51H 410 mph
F4U-4 374
Ta-152H 370
P-47M 365


It is a big aircraft but it has, by far, the most HP, 3600.

Do you have any more performance numbers for the Do-335?

[Zarathos]

It's based on polish book "Samoloty Luftwaffe" ("Luftwaffe airplanes"), by Marek Murawski and is in Poland considered as a good resource about German ww2 planes, so I think it's accurate.

According to the book Do 335A-1 SL speed was 580 km/h (or 360 mph). The Do 335 V1 (CP+UA), flown by Flugkapitan Hans Dieterle, in fourth flight, reached 600 km/h near ground (373 mph), but it was unarmed prototype and before changes made to solve problems with rear engine overheating.

Is your data good? Is it the last version, I think, the A?

Yes, it's for A-1 version. But A-1 was not the last verion of Do 335. The last version was B, or better to say, the pre-production prototype of B-2 version: Do 335 V13 (RP+UP). It made it's first flight at 31 october 1944.

Do you have any more performance numbers for the Do-335?

A little:

Engines: 2 DB 603E-1 engines, take-off power 1825 hp

Armament: 1 MK 103 cannon (30 mm, 70 rounds), 2 MG 151 cannons (15 mm, 200 rounds). Ability to take 1 SC or SD 500 bomb (500 kg) or 2 SC 250 (250 kg) bombs.

Speeds:
0m - 580 km/h (360 mph)
6400m (21000 ft) - 763 km/h (474 mph)
optimal cruising speed - 685 km/h (426 mph) at 7100 m (23350 ft)
best economic speed - 472 km/h (293 mph) at 6000 m (19700 ft)
landing speed - 180 km/h (112 mph)

Time to 6000 m (19700 ft) - 10 minutes
Best rate of climb - 23 m/s (4539 ft/min), but I dont have any data about altitude for that climbing rate.

Practical ceiling - 11400 m (37500 ft)
Range - 1380 km (858 miles)
Empty weight - 7400 kg (16335 pounds)
Starting weight - 9610 kg (21214 pounds)

I have somewhere monography of Do 335 (somewhere, I have to find it - my primary area of studies are VVS and LWP (Polish People Army) planes. When I find it, I'll post more data.

[davparlr]

Thanks for the info. I have very little on the Do-335.