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orion

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You think it has enough control surfaces?

Interesting to see that someone has actually gotten this far with this particular concept. From about 1980 on, I've seen maybe seven or eight programs who's goal was a jet-like airplane but with a pusher prop (not counting ducted fan attempts, which would put the total near a dozen). One of these was the ViperJet. There was also a seemingly well financed one in Arizona (tried a conventional prop - had really long gear), among the others. I'd guess about four out of the six or seven were financed well enough to where they should have gotten airborne. But none did.

Their failures seemed to fall into a few basic categories:

1) Prop issues: This covers two primary areas. The first is if you use a standard prop for the engine you selected. Generally this results in a fairly conventionally long prop, which then necessitates a very long gear if you want to make sure the airplane can still rotate. Stowing that gear then becomes a problem in that you not only need to find room but you still need to find a space for the fuel. Since the engine tends to sit close to the CG envelope, the only place left for fuel is now the somewhat crowded wing.

If you then modify the prop in order to have a shorter gear, you often compromise on the airplane's performance. This is especially so if you try to use a conventional prop, just cut down and re-twisted. It seems that this approach compromises the performance so much that it is no longer a viable product.

You can try for a custom prop but I don't know of any of these programs that were willing to invest enough to have this part done right.

2) Drivetrain issues: We've discussed issues of torsional vibration and remote prop mounting here before so I wont dwell on this. One of the programs I mention did run into disintegrating shafts and by the time they corrected the problem they added more than 120 pounds to the drivetrain, which then required a redesigned mounting and airframe structures.

3) Cooling: Buried engines like this require specific knowledge and experience to do this part right. The biggest single problem (with water-cooled engines) is that the designers tend to forget that this engine needs airflow around the block also. Cooling the radiator and oil cooler is not enough.

4) Then all these lead to secondary design problems, which when added up, often result in a program that either fades away or decides that with all this work and time invested (not to mention the invested funds), they might as well build a jet in the first place.

Since we didn't yet see that plane fly, I wonder where in the program they now sit.
 

Mac790

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You think it has enough control surfaces?
Orion,
No I don't, I think that's why they use both the h-stab and the canard, I also think that the h-stab may find it self in the wake from the wing so the elevator may stop working (in some circumstances, like landing approach etc), so it's another reason why the use canard at the front, I also think this plane has the worst access to the engine, I haven't seen worst. On the other hand it looks better than his first airplane pic1 (but of course it dosen't mean anything). Drivetrain, cooling and prop issues we were discusing in the "Personal Design" thread.

Thanks for your opinion.
Seb
 

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djschwartz

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I was at Reno the year that one of the derivatives, I believe it was Pushy Galore, went in. I was actually out on the one of the pylons at the time and saw it happen. We didn't know exactly what happened at first but it turned out it shed a prop blade and that tore the tail off which resulted in an immediate fatal crash. Very sad. For what it's worth, it also did not have a shroud around the prop. It had a more conventional T-tail arrangement.
 
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I notice that this thread is a bit out dated.......

I would like to re-open the conversation if anyone out there is interested in moving forward on the possibilities of a cold jet....

I have a prototype that uses some principles not yet thought about (except for a couple of Experimental Aircraft Scientist) that will eliminate the problems with the DEficiency's of a scale size ducted fan.....

There is one "current" operating model that proves the principles I am incorporating into this prototype are valid and feasable... It is unfortunate that these test on their prototype were much better funded than mine (we're talking millions more) in order for them to proceed with their development and testing quicker than I could.

I am using a similar "theory" for a different type of flight catagory and powerplant arrangement-..... Eliminating any possible copywrite infringments

I will have a working prototype for the non-VTOL powerplant that will bring sport sized military replicas to life for the Experimental conisure within 3-5 years....

Love to talk with open-minded persons about this---- however, any questions with regard to the mechanics or science of the prototype will require a non Disclosure agreement (papework is what is necessary to keep everyone civil and on the up and up in this day and age)

Any thoughts of encouragement are welcomed...
Any naysayers--- Please provide Scientific fact to your negativity and something besides "If it could have been done--- it would have already....."----- I am prepared to be wrong.... But, the argument had better be sound.

Looking forward to hearing what type of interest for my concepts are out there.....

Thanks

Quixote Douglas
aka
Christopher H Uchman Jr.
 

pie_row

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salt lake city Ut
Ducted fans are used on turbofan engines. That's a turbojet that has a fan that drives air through a duct around the engine core, rather than all of it going through the engine as in a straight turbojet. The turbofan makes sense on subsonic aircraft like airliners, and the higher-bypass engines (4:1 or more) are quite efficient.

The duct on these things is there to slow the incoming air and thereby increase its pressure. The fan tips need to stay subsonic, not easy to maintain, and a divergent inlet (cross-sectional area becomes larger as the air moves rearward toward the fan) has the effect of slowing it down.
AIRCRAFT ENGINE TYPE



McDonnell Douglas and one of the engine manufacturers (G.E.?) fooled with the Unducted Fan (UDF) in the 1970s but it didn't come to anything. This was basically a powerful turboprop with a many-bladed low aspect ratio pusher prop. They had a DC-9 with the usual low-bypass turbofan on one side and the UDF on the other. IIRC it wasn't any more efficient than the turbofan and had noise issues. They abandoned it.
Shadowgram of Mach3 Airflow


There was a small racing airplane with a shrouded pusher prop built in the '70s. It wasn't too long before the shroud disappeared and I think it's still flying without the shroud. Can't remember the name of the thing, but it was yellow or gold. Someone with a better memory might know it. I think this is it, or a descendant of it, by Jim Miller:
http://www.insideairracing.com/gallery/2000/IF1/50.jpg



Dan
pushy galore
 

pie_row

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Messages
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Location
salt lake city Ut
I notice that this thread is a bit out dated.......

I would like to re-open the conversation if anyone out there is interested in moving forward on the possibilities of a cold jet....

I have a prototype that uses some principles not yet thought about (except for a couple of Experimental Aircraft Scientist) that will eliminate the problems with the DEficiency's of a scale size ducted fan.....

There is one "current" operating model that proves the principles I am incorporating into this prototype are valid and feasable... It is unfortunate that these test on their prototype were much better funded than mine (we're talking millions more) in order for them to proceed with their development and testing quicker than I could.

I am using a similar "theory" for a different type of flight catagory and powerplant arrangement-..... Eliminating any possible copywrite infringments

I will have a working prototype for the non-VTOL powerplant that will bring sport sized military replicas to life for the Experimental conisure within 3-5 years....

Love to talk with open-minded persons about this---- however, any questions with regard to the mechanics or science of the prototype will require a non Disclosure agreement (papework is what is necessary to keep everyone civil and on the up and up in this day and age)

Any thoughts of encouragement are welcomed...
Any naysayers--- Please provide Scientific fact to your negativity and something besides "If it could have been done--- it would have already....."----- I am prepared to be wrong.... But, the argument had better be sound.

Looking forward to hearing what type of interest for my concepts are out there.....

Thanks

Quixote Douglas
aka
Christopher H Uchman Jr.

Well have you read my thread on M0.7~0.85? In order to make a bucted fan work you need a very high power density out of the powerplant. Not imposible but you need an out side of the box solution. One of my life goals is to build a powerplant that is 1,000hp out off 1.5L that would quite effectively drive a ducted fan airplane to as fast as you wanted to go give or take 25% of the speed of sound.
 

Topaz

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Well, a little search for any more information on the CC02 turned up exactly nothing, but I did find a nice video of the LH-10 Ellipse actually airborne. Nice to see.

 
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BBerson

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Well, a little search for any more information on the CC02 turned up exactly nothing, but I did find a nice video of the LH-10 Ellipse actually airborne. Nice to see.
That looks like a BD-5 with a narrow chord wing. In fact, that is less chord that I have ever seen before on anything. I wonder about the reynolds number effects on such a wing at low speed.
BB
 

Topaz

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That looks like a BD-5 with a narrow chord wing. In fact, that is less chord that I have ever seen before on anything. I wonder about the reynolds number effects on such a wing at low speed.
BB
Depends on their airfoil choice. Someone associated with this aircraft has posted here once or twice. Perhaps they'll join in and clarify the selection.

The airplane itself is a clean-sheet design, from what I understand, bearing only a visual resemblance to the BD-5. You'll note that this is a two-seater, quite a bit larger than the single-seat BD-5.
 

Topaz

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Well, I'll be darned. I found a couple of pictures of the CC02 actually airborne. Can't seem to link them into here, but here's the link to the page they're on. Scroll down a bit, about midway down the page.

Interesting. This guy's gotten a lot further than most of these faux-fighter projects. Of course, just because it flew doesn't mean it flew well, but I wish I could find out more about it! Seems to have flown in 2009 sometime, possibly June if I'm reading the French correctly.
 

Mac790

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bmcj

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Well, I'll be darned. I found a couple of pictures of the CC02 actually airborne. Can't seem to link them into here, but here's the link to the page they're on. Scroll down a bit, about midway down the page.
Neat looking (especially the plan view as seen inflight from the ground). However, when I look at it, it screams to me, "prop in disturbed airflow".
 
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Well have you read my thread on M0.7~0.85? In order to make a bucted fan work you need a very high power density out of the powerplant. Not imposible but you need an out side of the box solution. One of my life goals is to build a powerplant that is 1,000hp out off 1.5L that would quite effectively drive a ducted fan airplane to as fast as you wanted to go give or take 25% of the speed of sound.

Havent read it yet.... But on my way over to do so now....

Aluminum Viper V-10--- 505HP <only 500pds>. and tourque out the wazzzooo (525ft/pds at 3500rpms)
the ultimate Powerplant for experimental aircraft---

But no without a price
 
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