Question about engine placement

[Tony Williams]

We have to assume that the traditional front-engine layout was best for single-engined fighters, simply because nothing else tried worked as well.

However, for certain specific purposes, other layouts might have worked better. The P-39/63 was an interesting attempt, but I would have like to have seen a twin-tailboom pusher. Various examples of this were tried, but I think only the Swedish SAAB 21 made it into significant service, and that wasn't a particularly wonderful design.

The advantages of such a design ( unlike the SAAB, I am assuming a forward cockpit with gun actions/ammo storage behind the cockpit, and the gun barrels running underneath or to one side - think DH Vampire with a piston engine) include:

1) Excellent forward/downward visibility (particularly useful in ground attack or carrier planes)

2) Concentration of heavy armament in the nose without the penalties of synchronisation.

3) The possibility of mounting one heavy cannon in the nose for anti-tank purposes (possibly with the barrel running through the cockpit - all sorts of Freudian advantages here:) )

4) It would need a tricycle undercarriage, greatly improving forward visibility on take-off and landing (particularly useful in naval aircraft, or in close-support planes which need to use small forward airstrips - both of which also call for a tough, long-stroke undercarriage).

5) Variable weights (ammo and fuel) could be concentrated over the wing so the handling wouldn't be affected as they were used up (a problem for the P-39 with its forward ammo supply).

6) The engine (preferably an air-cooled radial) would provide a lot of added protection for the pilot from the most dangerous zone of attack - the rear.

Disadvantages?

1) Not too comfortable to bale out of (an ejector seat, or an explosive charge to blow off the prop, would be required).

2) Not too comfortable to crash into anything in a bad landing - the engine might end up in your lap, having passed through the rest of you....

3) Handling might not have been as good as a conventional fighter, although I don't think enough designs with this layout were tested to reach any definitive conclusions.

So, you could have ended up with a plane in two versions; a carrier-borne fighter-bomber, and an armoured ground attack/anti-tank fighter-bomber. It might have been a useful addition....

Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
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[RightF00T]

ahhh Tony this is what you want

http://www.aeroflight.co.uk/profile/d335hist.htm

[fdiron]

I've heard that the Do335 is the fastest piston engine production aircraft in the world.  Now I think the world record for the fastest prop aircraft is held by a highly modified Tempest.  

The U.S. used some mid and rear fuselauge mounted engine aircraft in the Vietnam War.  These were not high performance planes though.

[Tony Williams]

Originally posted by RightF00T
ahhh Tony this is what you want

http://www.aeroflight.co.uk/profile/d335hist.htm

No, definitely not - the Do 335 was a horrible plane! It had all of the disadvantages of a front-engined in terms of visibility and gun mounting, plus the disadvantages of a rear-engined plane! It had to be made very big because the fuel had to packed into the fuselage as well as two engines, a pilot and most of the armament.

If I wanted a heavy fighter, I would have chosen the DH Hornet - beauty versus the beast. The drag disadvantage of a conventional twin layout obviously wasn't that great as it could still manage around 470 mph...

Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
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[HoHun]

Hi Tony,

>If I wanted a heavy fighter, I would have chosen the DH Hornet - beauty versus the beast. The drag disadvantage of a conventional twin layout obviously wasn't that great as it could still manage around 470 mph...

Twin-engined fighters were known for a poor search view due to the engine nacelles blocking much of the view. With the pilot being located far behind the propeller disks, the Hornet certainly was affected by this.

The Hornet achieved its speed on 4120 HP, by the way, while the Do 335 only required 3500 HP for the same speed. With later, more powerful engines of the DB603 series, the Dornier would have been even faster.

Here's what Eric Brown of the RAE had to say about the Do 335 (from "Wings of the Luftwaffe"):

"The combination of features embodied by the Do 335 Pfeil rendered it unique at the time of its birth and it was destined to remain so, but had the Dornier warplane not appeared at the tailend of the piston-engined fighter era it is more than likely that its configuration would have been plagiarised."

Regards,

Henning (HoHun)

[Tony Williams]

Originally posted by HoHun
Hi Tony,

Here's what Eric Brown of the RAE had to say about the Do 335 (from "Wings of the Luftwaffe"):

"The combination of features embodied by the Do 335 Pfeil rendered it unique at the time of its birth and it was destined to remain so, but had the Dornier warplane not appeared at the tailend of the piston-engined fighter era it is more than likely that its configuration would have been plagiarised."
 

I have my doubts about that; I think that the layout was just too inconvenient. If more power was wanted, then other nations usually just fitted a bigger single engine. I don't know of any plans for a Do 335 look-alike.

I think a better twin-engine solution was the one used by the Douglas Mixmaster bomber, with two engines in the rear fuselage driving pusher props. This left the nose clear for a good view, armament etc.


Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
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[HoHun]

Hi Tony,

>If more power was wanted, then other nations usually just fitted a bigger single engine.

How many 3500 HP engines were there in 1944? :-)

>I think a better twin-engine solution was the one used by the Douglas Mixmaster bomber, with two engines in the rear fuselage driving pusher props.

Dornier documents indicate that they were thinking along the same lines - project P. 252 outlined an aircraft of just that layout. However, while the Do 335 was ready (and displayed top-notch perfomance) in 1945, P. 252 would have required quite a bit more development time.

Regards,

Henning (HoHun)

[Tony Williams]

Originally posted by HoHun
Hi Tony,

>If more power was wanted, then other nations usually just fitted a bigger single engine.

How many 3500 HP engines were there in 1944? :-)

Not quite that simple, Henning, as you well know! The penalties associated with two engines (even for the Do 335, you still have the extra weight plus the aft prop losing efficiency through working in air disturbed by the front prop)  means that you could design a single-engine fighter with the same overall performance as the Do 335 on a lot less power.

Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
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[HoHun]

Hi Tony,

The Do 335's high speed shows it was ahead of all other propeller-driven fighters at the contemporary level of engine technology. Its performance was only matched by later designs with advanced engines that resulted from additional development time. It was an exceptional design that could have competed with every other piston-engined fighter on an equal level of technology.

However, the era of the piston-engined fighter had just ended with the advent of the jet fighter.

Regards,

Henning (HoHun)

[funkedup]

There were contemporary fighters at the same stage of development in other countries that had the similar speed performance plus equal or better climb, maneuverability, range, and load carrying capacity.  Gimme an F7F or P-47N or F4U-4 or P-51H any ole day of the week.  

[fdiron]

Wouldnt mounting 2 englines in the fuselauge eliminate the drag penalities that an aircraft with engines on the wings had?

[Tony Williams]

Originally posted by fdiron
Wouldnt mounting 2 englines in the fuselauge eliminate the drag penalities that an aircraft with engines on the wings had?

That was the whole idea, and it worked to that extent. There were penalties associated with this solution, however, as indicated in earlier posts.

Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine
guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/

[HoHun]

Hi Funked,

>There were contemporary fighters at the same stage of development in other countries that had the similar speed performance plus equal or better climb, maneuverability, range, and load carrying capacity.

The corner parameters of the Dornier Do 335 were about 600 km/h at sea level, 760 km/h at 6 - 7 km altitude, and roll-out of the first series aircraft in November 1944.

I don't think any of the other high-performance fighters matched this combination.

Regards,

Henning (HoHun)

[funkedup]

P-47N-1 were coming off the line in September 1944, P-47M were delivered in December.  M and N were just as fast as the 335, although I think the 335 could climb better than the fuel-heavy N.

P-51H was capable of almost 490 mph, and was produced starting in January 1945.  It could easily outclimb and outmaneuver the 335 as well.

F4U-4 and F7F were ~20 mph slower than Do 335 but superior in all other aspects, starting mass production in April and September 1944 respectively.

I agree that these aircraft all had better engines than the DB 603, but they were definitely contemporary designs.  I think the most impressive thing about the 335 is that it was able to fly so fast with what was basically a dog of an engine.  Compare it to the Me 410 and it's a hell of a machine.

[2Late4U]

Originally posted by fdiron
The P39, with its engine behind the pilot, had a very streamlined shape.  This also allowed the P39 to have a 37mm cannon mounted in the nose.  Why didnt other U.S. fighters have their engines placed behind the pilot?  It seems this would have many advantages such as lower drag and better aiming for weapons.  It could also possibly protect the engine for hostile fire. If the engine was mounted over the center of gravity I dont see any negative effects of this arrangement.

Why dont you try and bail out of an aircraft with the props behind you....hmmmm....seems like just a slight problem:eek: