Single-engined pusher planes: any role for those?

[tyrodtom]

Surplus P-51's costing a lot less than building new J-21's might have had some influence on their decision.

[FLYBOYJ]

You have a point but understand that Sweden never intended to procure the P-51, fate determined that. Had the Mustangs not been avainlable or WW2 lasted longer, be rest assured the 484 planned J21s "would have" been produced.

Bottom line this aircraft did work and if you take into account that it did serve at least 4 yesrs did show that a pusher design was developed during WW2 with limited success. Could it compete with aircraft like the P-51 or later model BF-109s? Never. But it did provide Sweden for what was needed at the time, an indigenous fighter that could at least ensure the country's neutrality.

I see nothing in any Internet sources about this aircraft that because of its configuration it was limited by CG issues during normal course of operation. If anything it seems that if it had a better engine it might of performed better, the latter of my statment being my opinion...

[FLYBOYJ]

Surplus P-51's costing a lot less than building new J-21's might have had some influence on their decision.

I believe these were "gifted" to the Swedish Government after hostilities, so yes, such a deal!

[Elmas]

I don't think that money was, and still is, a real concern for Swedish Air Forces, as they prefer to develop their own planes ( with the related costs ...) than to buy foreign material.
By my personal point of view, to buy a bunch of, say, Sabres or F 16s could have been much cheaper than to develop all their machines, excellent as they can be.

In a beautiful book by J. Quill, whose name you certainly know, almost a whole chapter is dedicated to longitudinal instability of the Spitfire, for a CG exceedingly backwards.....
The Spitfire! a machine that was loved by her pilots for the delightful handling.....

By my point of view, instead, a more powerful piston engine means also an heavier one and in a propeller pusher that means a CG more backwards that must be compensated by weight in the front etc.: have you ever heard about the Varignon's theorem, which states that the moment of a force about any point is equal to the sum of the moments of the components of the force about the same point, and about the equilibrium equations?
It's a dog chasing his tail.
That was easily solved by jet engines, much lighter than piston ones.

Et de hoc satis, as the ancient Romans used to say, at least for me.

Cheers

[tomo pauk]

Any plane that received a heavier engine in front (Spit IX -> Spit XIV, Bf-109D -> Bf-109E etc) was subject to what you say. Issues were solved, and nobody looked back at predecessors.

[FLYBOYJ]

I
By my point of view, instead, a more powerful piston engine means also an heavier one and in a propeller pusher that means a CG more backwards that must be compensated by weight in the front etc.: have you ever heard about the Varignon's theorem, which states that the moment of a force about any point is equal to the sum of the moments of the components of the force about the same point, and about the equilibrium equations?
It's a dog chasing his tail.
That was easily solved by jet engines, much lighter than piston ones.

Et de hoc satis, as the ancient Romans used to say, at least for me.

Cheers

The P-51 for the Sweeds was a winfall although they were bending the rules on their own arms policies. Be rest assured that aqusition affected and probably comdemed the J21 program. It did not prevent the Sweedes to continue to design and build indigenous fighters and still deploy the J21.

Varignon's theorem? Know it well - I've done weight and balance on dozens of aircraft of all classes for many years. Have you proven that any WW2 pusher fighter designs was plagued with the limitations stated in your original statement? Agree they did not live up to their tractor counterparts but I have yet to read or hear anything about any WW2 pusher aircraft that had CG/MAC problems because of expended payload issues. Most if not all of them did have stability issues that had nothing to do with expended payload, ie - ammunition. If you have data, please share!

What about the Dornier 335? - a combination of both pusher and tractor. Do you feel that same about that aircraft?

[Elmas]

As you probably know Decimomannu is ( or better, was, before 1991....) one of the most important Nato Airports in the world and it is few miles from my home.......
And for some reasons I had the possibility and the pleasure to have long talks with both Pilots and with my Colleagues Engineers, both Civil and Military, with a beer or a bottle of scotch in front of us....
I have seen the first flights of the Typhoon there, when one of the prototipes was performing the armament trials at the Capo Frasca firing range....... I could tell you some amusing little strories about, but I don’t want to go O.T......

What about the Dornier 335? - a combination of both pusher and tractor. Do you feel that same about that aircraft?

Of course not. But I can't see any similarity in terms of static balancing among the J 21 ( wich had only one engine, behind the CG) and the Dornier 335 ( wich had two, one in the front and one behind).



So, no problems at all for the latter about static balancing ( centraggio, in Italian): all the consumables can be easily placed at, or near, the CG: look at the main fuel thank just behind the pilot’s seat, on the leading edge of the wing, as the main armament, on the leading edge as well.

But, as aeroplanes are real life, and in real life noboy gives you something for nothing......... the distribution of the masses of two engines fore and aft of the CG and at distance from it, gave the Dornier a very high Moment of Inertia (rotational Inertia) in the longitudinal axis so a very careful handling of such an heavy plane was, I think, also needed.
But, of course the Pfeil was designed to be a powerful opponent to the B 17s, and not to make loopings and immelmans.....

[tomo pauk]

What a beauty, the Pfeil.
Wonder if a similar piece would do anything good for Allied cause. Or Axis, for that matter, with 601s (hallo, Dave )New what if topic...

[gjs238]

CAS. A rear prop normally provides superior forward visibility

We've had quite a bit of discussion regarding deflection shooting vs. view over the nose. A rear prop with the pilot far forward might be excellent for deflection shooting.