He177 Speed and Climb

[krieghund]

I found this document on Luftwaffe Cockpitinstrumente Homepage Titelseite Instrumente Gertebrett Baumuster

I have found various references to the max speed of the He177 from 480 kph to 521 kph at 6800m. This chart shows about 550 kph at climb and combat power of 2500ps each at 1.3 ata. So how fast does it go at 2710 ps each at 1.42 ata at the same altitude?

 

[Vincenzo]

beautifull charts thank you for sharing

 

[HoHun]

Hi Krieghund,

>This chart shows about 550 kph at climb and combat power of 2500ps each at 1.3 ata. So how fast does it go at 2710 ps each at 1.42 ata at the same altitude?

As a quick estimate, topspeed increases to the cube root of power.

So the speed you're looking for is approximately:

V = V0 * (Pmax / P0)^(1/3) = 550 km/h * (2710/2500)^(1/3) = 565 km/h

In practice, it might be less than this due to decreasing propeller efficiency due to the higher rpm, or more than this due to increased exhaust thrust

Regards,

Henning (HoHun)

 

[delcyros]

as a best guess:
SL:
450 km/h @ 1.3 ata = 462 Km/h @ 1.42ata
6.400m:
550 km/h @ 1.3 ata = 565 km/h @ 1.42ata

Practical top speed will be a bit higher than this due to
A) induced drag is a less prominent factor at all out level speed than at slow speed (the power required to achieve 565 km/h is slightly less than the cube root of power of the two power ratings)
B) the engines critical altitude increases at 1.42ata due to ram effects
C) the amount of exhoust thrust increases due to increased altitude of critical altitude and higher engine ata ratio.

A conservative guess would circle around 570-580 km/h (354 to 360 mp/h) at ca. 6.700m altitude at a gross weight of 26.000 kg. Correspondingly it would be slower at heavier weights (or external stores) and faster at lighter loads.

 

[Kurfürst]

From German type sheets from 1 June 1942.

A-1 (DB 606)

Max speed: 545 kph at 6km (at maximum power, without external loads)
service ceiling: 8,8 km at 24860 kg (=max TO weight - 1/2 fuel - bombs)

maximum range: 5350 km at 415 kph, with 1 t bombs and 8910 kg (11900 liters) of fuel.
maximum load range: 2200 km at 415 kph w. 7.2 t bombs and 2800 kg fuel


A-3 and A-4 (DB 610)

Max speed: 565 kph at 6.5km (at maximum power, without external loads)
service ceiling: 9,4 km at 25000 kg (=max TO weight - 1/2 fuel - bombs)

maximum range: 5300 km at 415 kph, with 1 t bombs and 8900 kg (11900 liters) of fuel.
maximum load range: 2100 km at 415 kph w. 7.2 t bombs and 3100 kg fuel

 

[Vincenzo]

in other thread you attachè a sheet that give max fuel at 12660 liters and with max bombs ~70% of fuel. and commonly i read Max TO weight over 30 tons. max bombs maybe 7 tons (2*1800 and 2*1700)

 

[JAG88]

Question, how can we interpret these numbers when compared with those provided by alejandro in another thread?

It seemed that 550kph was possible at 26t, but the later chart seems to indicate 480kph max at the same weight.

Thx in advance.


JAG

 

[Vincenzo]

Sorry too small for me

 

[Denniss]

The two rows on the right for the A-5 are with Fla-V (flame dampers). A power loss of 5% is noted because of the Fla-V.
The He 177 A-3/R2 of the first row is equipped with HS 293 glide bombs.
The speeds seem far too low and the FTH heights do not really match. 5.8 km is the static FTH heigt for the DB 605A in emergency power, with climb/combat setting the static FTH rises because the engines does not need that many air as in the higher rev/boost setting. RAM effects add even more FTH - max speed should be achieved at about 6.5-6.8 km/h, just like the Bf 109/110 with the DB 605A engine.

 

[Juha]

Hello Denniss
IMHO bombers were a bit different animals than fighters, for ex Hurricane Mk IIs (Merlin XX) achieved their max speed at 21,500ft according to Jane's but Lancaster B. Mk I W4963 (Merlin XXs) at 13.000ft at 60,000lb according to A&AEE report.

Juha

ADDUM Personally I have more faith on GL/C-E 2 from June 44 than Heinkel's data from Dec 42

 

[JAG88]

Sorry, this should make it clearer:

http://www.ww2aircraft.net/forum/at...7083-b-17-vs-he-177-vs-lancaster-p1100048.jpg


JAG

 

[Vincenzo]

ty for the large

the "new" image are for 31 ton heavy 177, the first row sure with external loads (2x Hs293) the other 2 with reduced power and probably ever with external loads
so it's nothing strange that speed is lower of 1st image (550 km/h). afaik weight and drag penalize also altitude so again nothing strange

 

[Juha]

Hello Vinzenco
in fact the only figure given to 31 tons a/c was the fast cruise figures for A-3/R2, also its fast cruise figure at 25,3tons weight is given, all other speeds are those of at Gm, that is at 25,9/25,3tons.

Juha

ADDUM: Rüstungzustand B, the middle row, means medium range bomber configuration, that means max 4 tons of bombs and He 177A-5 could carry those internally.

 

[JAG88]

Hello Vinzenco
in fact the only figure given to 31 tons a/c was the fast cruise figures for A-3/R2, also its fast cruise figure at 25,3tons weight is given, all other speeds are those of at Gm, that is at 25,2/25,3tons.

Juha

Yeah, I understood the same only that I read the Gm at 25,9, with no speed given for Ga or 31t.

Would Gm coincide with "equipment condition B"? Medium bomber?


JAG

 

[Juha]

Hello JAG
yes, sorry, You are right, Gm was 25,9 tons for A-5 and A-6 and 25,3 tons for A-3/R2. The Ga in the first row is the 31 tons figures for A-3/R2, Gm is not connected with equipment conditions, IIRC its theoretical "near target condition", around 80% of AUW.

Juha

 

[Denniss]

I forgot the flame dampers, they probably also affect engine FTH from increased exhaust resistance.
Still doesn't explain why the A3 in row 1 is as slow as the A-5 with flame dampers.

 

[Vincenzo]

Hello Vinzenco
in fact the only figure given to 31 tons a/c was the fast cruise figures for A-3/R2, also its fast cruise figure at 25,3tons weight is given, all other speeds are those of at Gm, that is at 25,9/25,3tons.

Juha

ADDUM: Rüstungzustand B, the middle row, means medium range bomber configuration, that means max 4 tons of bombs and He 177A-5 could carry those internally.

my fault i read too fast the image.

However there is little change in the argument. the first row with 2 Hs 293 external load give a max speed (30' rating) to 480 km/h at 5.8km, it's impossible that the 2nd row give data for internal load, the small gain in the speed of the 3rd row (+10 km/h) probably it's from less drag of the smaller external load

 

[Juha]

...However there is little change in the argument. the first row with 2 Hs 293 external load give a max speed (30' rating) to 480 km/h at 5.8km, it's impossible that the 2nd row give data for internal load, the small gain in the speed of the 3rd row (+10 km/h) probably it's from less drag of the smaller external load

Hello Vinzenco
why impossible? It is clearly stated that both A-5 and A-6 figures are with flamedampers, ie with 5% less power and more drag. so slower than without them. In A-3/R2 the external loads are clearly stated, nothing like that in A-5 and A-6 rows. And normal Rüstzustd. B and C (long-range bomber) are with internal bomb loads, at least in Flugzeugtypenblatt for He 177 dated 1.1.42. A-6 had only the forward dorsal turret, so less drag, it also had a tail turret, so it has a bit different fuselage than A-5.

Juha

 

[JAG88]

Thx to all for your answers, I am astonished to see such a difference between the 1942 Heinkel data prepared after the initial DB610 trials and the 1944 info, I certainly didnt expect it and I wonder if there is further data on this aircraft that may shed more light on the issue.

Any idea regarding its never exceed speed or up to what speed it could "dive"?

Was the 5% less power rating a precaution to prevent overheating?

Crazy idea, was the 480-445km/h its true highest possible speed at that load (which seems low) or the max speed it could attain and still maintain the range indicated for the long range configuration and 3t of bombs?

Is 550km/h its speed for the return trip? ie without bombs and light on fuel?

 

[Juha]

...Any idea regarding its never exceed speed or up to what speed it could "dive"?

I might have Vne somewhere but I don't have now time to try to dig it out

Was the 5% less power rating a precaution to prevent overheating?

Not to my understanding, but I'm historian not engineer. But sometimes the overheating of flamedampers was a problem but Germans put plenty of cooling air into their flamedampers.

Crazy idea, was the 480-445km/h its true highest possible speed at that load (which seems low) or the max speed it could attain and still maintain the range indicated for the long range configuration and 3t of bombs?

480-445km/h was with Kampf und Steig power, that was allowed for 30min, not Start und Not, which was max allowed power for 3min or 1 min, maybe it wasn't very safe to use Notleistung with DB 606/610 anyway.

Is 550km/h its speed for the return trip? ie without bombs and light on fuel?

Dont know but for ex Ju 88 A-4 had max speed of 408km/h at 5500m at 13,75 t (with 2xSD 1000) and on return trip could achieve 453km/h at 10,8 t (bombs dropped) at 5500m
He 111H-16 had max speed of 405km/h with AUW 14t and 435km/h after dropping its bombs and after having used ½ of its fuel load.

Juha