Why have American DH.4s such a bad climb?

**Honza** · 04-17-2022 04:12

Why have American DH.4s such a bad climb? I thought they were equipped with 400hp Liberty engines.

**Jager** · 04-17-2022 09:02

There's not a lot of difference between the 400hp Liberty and the 375 Eagle engine that most of the UK DH-4s were powered with.
Karl

**Honza** · 04-17-2022 09:13

And what made the difference?

**Angiolillo** · 04-17-2022 11:50

I have these data for the D.H.4.

Engine	time to altitude (minutes.seconds/meters)	Ceiling (meters)
230hp B.H.P	3.18/608, 11.48/1520, 24.36/3040.	4114
200hp R.A.F. 3a	1.25/304, 8/1981, 25.15/4267, 41.3/5181.	5334
230hp Puma	7.3/1981, 14/3040, 28.3/4560.	5303
375hp R.R. Eagle VIII	4.5/1828, 9/3040, 14.45/4267, 23.3/5486.	6705
400hp Liberty 12	8.3/1981, 14.48/3040, 33.42/4560.	5334

**Diamondback** · 04-17-2022 15:11

IIRC, weight. The Liberty was a powerful engine, but its power to weight ratio was hot steaming garbage. Might as well pack the nose full of boat anchors...

**flash** · 04-18-2022 02:20

The DH.4 started with 250 hp (190 kW) Eagle III engines and subsequently built with improved versions of that engine until the 375hp R.R. Eagle VIII was developed. It was the shortage of supply of that later engine that led to it being fitted with the Liberty L12 and other engines listed by Andrea. I wonder what the stats of those earlier RR types would look like ?
Currently the model uses the fast deck H - fitted with the Eagle VIII the (wiki) stats suggest it could be used with the very fast A* deck - 143mph (230kph) at sea level so, potentially, maybe this model could be used at different times with different deck speeds ? (*sans Immelmann)
I've used it in the past with the average speed K deck as a loaded weight, switching to the H deck once it dropped it's eggs for a fast getaway. It worked well and allowed the intercepting Fokker D.VII's a chance to catch their targets on the way in.

**Honza** · 04-18-2022 03:58

Thank you guys!

**john snelling** · 04-18-2022 06:59

Originally Posted by Diamondback

IIRC, weight. The Liberty was a powerful engine, but its power to weight ratio was hot steaming garbage. Might as well pack the nose full of boat anchors...

I agree with this assessment.

**Jager** · 04-18-2022 12:58

Originally Posted by Diamondback

IIRC, weight. The Liberty was a powerful engine, but its power to weight ratio was hot steaming garbage. Might as well pack the nose full of boat anchors...

I should have remembered that

That's why the Liberty-engined Bristol fighter was such a failure!
Karl

**Flying Helmut** · 04-18-2022 13:19

The Liberty might have been rated at 400 HP, but in practice it delivered considerably less.

Its power-to-weight ratio was very poor.

**Jager** · 04-19-2022 12:46

Originally Posted by Flying Helmut

The Liberty might have been rated at 400 HP, but in practice it delivered considerably less.

Its power-to-weight ratio was very poor.

But, hey; made in the USA, so it's all good

Karl

**Diamondback** · 04-19-2022 18:19

Originally Posted by Jager

But, hey; made in the USA, so it's all good

Karl

That's what Detroit said until Toyota and Honda beat them up and took their lunch money, too...

**Bobsalt** · 04-19-2022 18:57

Originally Posted by flash

The DH.4 started with 250 hp (190 kW) Eagle III engines and subsequently built with improved versions of that engine until the 375hp R.R. Eagle VIII was developed. It was the shortage of supply of that later engine that led to it being fitted with the Liberty L12 and other engines listed by Andrea. I wonder what the stats of those earlier RR types would look like ?
Currently the model uses the fast deck H - fitted with the Eagle VIII the (wiki) stats suggest it could be used with the very fast A* deck - 143mph (230kph) at sea level so, potentially, maybe this model could be used at different times with different deck speeds ? (*sans Immelmann)
I've used it in the past with the average speed K deck as a loaded weight, switching to the H deck once it dropped it's eggs for a fast getaway. It worked well and allowed the intercepting Fokker D.VII's a chance to catch their targets on the way in.

You bring up something here I’ve wondered about. Has anyone ever created some sort of table for switching decks when a plane drops its bomb load?

**Jager** · 04-20-2022 09:32

Originally Posted by Bobsalt

You bring up something here I’ve wondered about. Has anyone ever created some sort of table for switching decks when a plane drops its bomb load?

Not that I know of, but I've often downgraded a bomb-carrying 2 seater to the next slower deck.
What Dave mentions above with the K deck for a loaded DH-4 is exactly what I do.
I find this works much better than a required stall move in each turn; that's very jarring.
Karl

**Honza** · 04-20-2022 10:13

Do you guys play steep maneuvers while loaded?

**Flying Helmut** · 04-20-2022 10:14

Of course!

Climb, Dive and Stalls are all "steep", and can all be played while "loaded".

**Honza** · 04-20-2022 12:53

Steep 90 turns and wide side slips may be too much.

**flash** · 04-21-2022 02:26

Originally Posted by Honza

Steep 90 turns and wide side slips may be too much.

I've only used it with tandems, more as a mechanic to allow the interceptors to intercept and as Sam says it makes thing a bit smoother than using a stall every turn. The only tandem with a steep 90 turn is the Hannover & I'd allow it as its few bombs are carried internally. None have a wide sideslip, steep or otherwise. It's not steep but I wouldn't allow the Immelmann card for the few that have it.

**Flying Helmut** · 04-21-2022 05:18

Originally Posted by flash

I've only used it with tandems, more as a mechanic to allow the interceptors to intercept and as Sam says it makes thing a bit smoother than using a stall every turn. The only tandem with a steep 90 turn is the Hannover & I'd allow it as its few bombs are carried internally. None have a wide sideslip, steep or otherwise. It's not steep but I wouldn't allow the Immelmann card for the few that have it.

Agreed.

In WGS, the Immelmann is banned for planes carrying ordnance.