Centerline Thrust Prop Engined What-If

[Scooterman]

That sir is totally bad donkey!
       

[kitnut617]

there are some interesting advanced engine concepts using the concept of the Crecy and these are 'X' configured 24 cylinders and also have theoretical power of 8000 hp.

Do you mean your model would have 16,000hp with a so tiny drag? Which maximum speed? 900km/h? (550mph?) What a thrill with piston engines...

Yes these two stroke engines that Rolls Royce were working on was so that the aircraft would go beyond  500 mph and up to 600 mph.  The limiting factor was propeller design but we know that there were prop driven aircraft that could do around 600 mph.  The Convair XFY-1 Pogo flew at over 600 mph in level flight with only 5800 hp.  The Tu.95's were chased doing nearly 580 mph. Both of these had larger diameter props than what I was thinking off

But it all came to nothing because of the jet engine.

Cheers,  Robert

[Tophe]

But it all came to nothing because of the jet engine.

Dear, please don't say "it came to nothing": it came to THIS model of yours, which is a beautiful monster!  

[Mossie]

Hi Robert, I like it!  It reminds me of the BAe propfan Small Agile Battlefield Aircraft concepts.  What role would your aircraft have had?  Have you thought of a name?



Simon

[Gary]

There is a Russian rig that looks a lot like that too. It was posted a long time ago, and I started cobbling up a Mig 29 with fans on a Seafury hub. Dided in the distraction pile. Should ressurect, but too fricken lazy.

[kitnut617]

Hi Simon,  

I was thinking of it being a fighter or ground attack, it's twin engined but both engines are in tandem in the rear fuselage, the front engine driving the front props by shaft.  I was thinking of a quick firing cannon like what is used on a F.5, (which IIRC is about 3000 rounds p/m) firing through the spinner, like a P.39.

I've read, but someone might be able to correct me, that contra-props are better for quick acceleration so it could be used like GTX has commented on, as a Reno racer.

As for a name, that's a toughy, I'm not sure what to call it, I've not really given it much thought.  Reading one of the posts about how imaginative the manufacturers are getting (not!) it's going to be hard coming up with something original but not silly, like some names that were coming up on the Airfix forum that time, remember.

Cheers,  Robert

[naoto]

For some reason this URL popped into my head...
http://www.stavatti.com/

[kitnut617]

For some reason this URL popped into my head...
http://www.stavatti.com/

Are those ever neat

Where did you find this website?

Robert

[John Howling Mouse]

This is a bit crude as I'm by no means an expert on digital photo-edit but here is how your fantastic idea would look without the nose props (just to compare)...

[kitnut617]

Now that does look neat like that, John.  I'm already thinking of what Jeffry had suggested, four rows of props at the back B)  B)  B)

 Robert

[kitnut617]

One of the ideas I thought about for this was a 'Time-to-climb' record.  Amazingly, the record for an aircraft, from stand-still on a runway to 3000 meters is held by a small Formula 1 Reno racer,  which I can't remember what it's name is, Nemesis I think.

My thought would be to have the front prop set at reverse thrust, the rear prop at full corse pitch, brakes on and full power.  Release the brakes at the same time putting the front prop into full corse.  With a projected 16,000 hp it should just about leap off the runway.    B)

[jcf]

Very neat...but I agree with JJ, the front props look out of place to me. But then again, I know nowt about this centreline thrust concept you speak of.........

The centerline thrust is not a new idea, it being pioneered by Dornier.  Most of their flying boats were this configuration.  I think though the most advanced one was the Do.335.  This was an amazingly quick aircraft where on one occasion a Tempest pilot came across one and gave chase, but was left behind very easily by the German pilot.  It has been used by Cessna on their O-2 FAC aircraft and a couple of others which I can't remember their names right now, one is quite a modern composite business aircraft.

Cheers,  Robert

I believe the proper term is "multi-engined centreline thrust"...as pretty much all single engined aircraft, prop or jet, have the thrust line going through the center of the aircraft. I realize that some publications out there simply refer to it as Centreline Thrust-CTL...but frankly that is laziness on their part.

The Cessna aircraft were the Models 336 and 337(and never was an aircraft more appropriately numbered) and the modern aircraft is the Adam A500:


The Dutch also had a tandem engined fighter, the Fokker D.XXIII, prior to the war, and the Russians built the Moskalev Sam-13.




Cheers, Jon

[kitnut617]

There you go !! that's the one.  And I had fogotten about the Fokker, I seem to remember that you can buy a model of that too.

Robert

[Tophe]

Remember also the RS kit of Marson twin-boomer we discussed at http://www.whatifmodelers.com/forum//index...?showtopic=4080
I have got one, not already built nor started...

[kitnut617]

Looks impressive!  For something that looks like it started life as a MiG-29, this is a real change.  

Personally, I like the rear mounted propellers, but the pair up front are in the way.  Getting all of the propellers installed on the rear would be the best option.  Since you are going with the counter-rotation idea, why not take it a step or two further for the "UNDUCTED FAN" concept and have all four sets of propellers at the rear counter-rotating in unison to create the UDF effect.  

What scale is this and what propellers are you using?

Funny you should mention Unducted Fans, I was just reading in my latest issue of Torque Meter (the Journal of the Aircraft Engine Historical Society) about an unducted fan engine.  This was an unusual design which GE developed as an ultrahigh bypass engine which featured contra-rotating fans driven by a free power turbine in which both the blades and the stators rotated.

The whole design would work very well for a very high powered piston engine, especially one of the 'X' or radial configuration as the exhaust could be piped into the power turbine very easily.  It would work very well in a real thing of my model here.

Robert