Custer Channel Wing

[eflightray]

There has been a couple of threads running in two other forums, discussing the merits of the channel wing design.

Now I didn't wont to step on any toes there as my knowledge of airfoils and air flow is rather limited, I'm more of 'if it looks right, it'll fly right' designer.

But some of the posters seem to be of the opinion that a channel wing has VTOL capability.

Now for the life of me I cannot understand how blowing air fast through a channel, (half a ducted fan style?), is going to create enough lift to give VTO. Yes air flowing fast over an airfoil will create lift, but isn't it also related to wing area and especially load.
The gist of some of the points raised is that wings aren't needed, only the channel(s).

So is there anyone here with true aerodynamic knowledge that can say whether a channel wing configuration could ever achieve VTOL, no matter how clever or well designed to internal airfoil in the channel is.

[JetPlaneFlyer]

Yes it should be capable of zero length take off run, given enough power.

You are correct that lift is proportional to wing area but it's also proportional to velocity squared, so if you can get the velocity high enough the wing area can be very small indeed (ever seen an F104 starfighter fly?)

[Tom Harper]

The idea looks neat, but if you draw the lift vectors, only one of them points straight up.

[eflightray]

Yes it should be capable of zero length take off run, given enough power.

You are correct that lift is proportional to wing area but it's also proportional to velocity squared, so if you can get the velocity high enough the wing area can be very small indeed (ever seen an F104 starfighter fly?)

But I've never seen an F104 do a VTO.

Are you saying that the channel wing can 'suck' itself into the air, this is what I don't understand.

[nmasters]

Given enough watts per pound anything is capable of VTO. The channel wing worked (not well but it did work) but didn't have any practical application. Nothing wrong with building dumb things as long as you don't delude yourself into believing that you're you're investigating the secrets of the universe. It's fun to make obsolete technology work bu it's just play

[BMatthews]

One of the promo pictures shows a Custer airplane being held back by ropes and the wheels are off the ground. This was supposed to be a proof that the channel wing provides some lift ability. But it's not just the channel wing segment lift. The airplane is also angled up quite strongly at around a 25 degree angle so it's sort of a blend of the channel wing lift as well as the thrust vector.

The Custer wing has always intrigued me. One day I really want to make up a test section and get some actual numbers from it. There's no doubt that a lot of mystery is part of the Custer saga.

[eflightray]

.......................
The Custer wing has always intrigued me. One day I really want to make up a test section and get some actual numbers from it. There's no doubt that a lot of mystery is part of the Custer saga.

You need to have a look at the following two threads - The Custer effect/Foamies /KF airfoil ... ??? (http://www.rcgroups.com/forums/showthread.php?t=813637)

and Custer wing Design in VTOL (http://www.rcgroups.com/forums/showthread.php?t=621903)

They seem to be doing quite a bit of research.

[JetPlaneFlyer]

But I've never seen an F104 do a VTO.

Are you saying that the channel wing can 'suck' itself into the air, this is what I don't understand.

Any wing 'sucks itself into the air'... ie. the pressure on the upper surface is less than the pressure on the lower. The Custer idea is no different in principal. The one practical difference is that on the Custer design the air is moving and the wing is stationary, whereas on a conventional aircraft it's the wing that moves through the air.
Think of the Custer wing to be like a conventional aircraft taking off into a huge headwind... only the Custer makes its own headwind.

The idea is actually used in some modern jet aircraft in the form of blown flaps or over-the-wing-blowing.

Unless the thrust vector was angled steeply upward it would not give vertical ascent, as in true VTO, because the thrust would always cause the aircraft to accelerate forwards... That's why I said zero length take off run rather than vertical take off... there is a difference.

[Tom Harper]

Yes, but:

Only about 60% of the wing produces a vertical vector the remaining area is in the walls which oppose each other.

When the channel produces lift it also produces tip vortices - they would likely fold into a torus that would absorb energy. Might raise havoc with any attached flat surfaces.

I picked up this old Custer stock certificate someplace. It shows the one airplane they made. I understand that the performance was similar to a conventional airplane with similar power and projected area.

[Brandano]

But with a structurally complex and heavy wing spar. It might have better STOL behavior, having a bigger portion of the wing affected by the prop's airflow. However, only the component of lift pointing upward from the wing contributes to flight. In any case, it still has to follow the "no free lunch" rules. For it to take off vertically the motor needs to be powerful enough to lift it vertically. An F104 could take off vertically, if it had an engine with a thrust higher than its weight ans was set up as a tailsitter. Naturally, that's completely impractical

[coosbaylumber]

There was a huge article written by one of the kids of Chester Custer. The airframe is not really new, it was designed in the 1930's but seemed to take a decade from mailing until a patent was issued. According to the article, it was not a VTOL design, but a STOL design. And odd at that.

Per the stock certificate picture, the biggie hope was on the Brigadier. This was built, and then the Gov't refused to contruct more small airports and it stopped funding many small ones it had in the past. Which shot the need for the Brigidier.

Per tests, the Brigidier was taking off the ground in about 200-300 feet, at about 40-50 MPH. fully loaded. It had then to obtain a steep climb out, and then level off, and cruise at about 150 which made it good for the anticipated commuter uses. Was no mention about landing it, only the take off. My suspect was that it landed longer than it took off or was quite rough.

But, find the Wings or Airpower issue of early 1980's done by the kid. It was reported in a follow up edition that the Brigidier was seen sitting for some time at like the Kingman airport. Then disappeared.


Wm.

[warhead_71]

You guys are postulating instead of researching.

Custer made 5 different prototypes (that I know of), and they all flew beyond anyone's expectations, (though controls had to be sorted out since ailerons don't work at zero airspeed). The reason the plane never went into production isn't because it didn't work... it worked exceptionally well. The problem was bad timing and bad politics. Some guy named Sikorsky was promoting a new invention called the "helicopter" at the same time that Custer was promoting the CCW... and Sikorsky had better political connections and was more business-savvy. Custer, on the other hand, was a grumpy old fart. A major manufacturer offered to buy his design but Custer wouldn't sell unless he got to lead the R&D department... egos flared and he lost the offer. Doesn't change the fact that the plane flew well and had incredible amounts of lift per horsepower.

Sort of like Edison and Tesla... everyone knows Edison created the lightbulb, but few people remember that Tesla invented alternating current, AC motors, radio, microwaves, laid the groundwork for quantum physics, ion propulsion, the list goes on (he could even light up a field of light bulbs with no wires... wireless lighting!)-- he was "brighter" than 100 Edisons, but because he wasn't a a good salesman he died penniless and has since almost been forgotten.

I digress...

Anyway... yes, the plane was designed to be SuperSTOL, not VTOL, though it would hover in a nose-up attitude if tethered to a pole. The nose up attitude does have to do with balancing prop thrust with the wing lift...

I just have to comment on this :
"Given enough watts per pound anything is capable of VTO. The channel wing worked (not well but it did work) but didn't have any practical application. Nothing wrong with building dumb things as long as you don't delude yourself into believing that you're you're investigating the secrets of the universe. It's fun to make obsolete technology work bu it's just play"

Bullcrap.

It's worth noting that the CCW produces more lift per horsepower than any "conventional" aircraft to date, while retaining the same cruising capabilities (speed, duration, ceiling) of similarly sized and powered aircraft. Landing was just the same as taking off... slow airspeed, short runway, high-alpha approach. There is no STOL aircraft built today that can beat the lift-per horsepower... the channel is just so much more efficient than a conventional wing. There is video on YouTube of an early prototype in flight. The short take-off is truly amazing.

[eflightray]

So I just have to ask the question, in a world where the cost of fuel to payload is so important, why aren't there any flying today?

I can't believe it's just because of patents.

[JetPlaneFlyer]

So I just have to ask the question, in a world where the cost of fuel to payload is so important, why aren't there any flying today?

I can't believe it's just because of patents.

Like i said in my previous post... 'Over the wing blowing' and 'blown flaps' use exactly the same principal and can be found on many aircraft. The advantage of these methodes over the true Custer Channel is that the wing blowing can be turned on or off as desired. The custor channel however is creating extra velocity over the wing (and therefore extra drag) all the time, whether it's needed or not.
So I guess the fundamental problem with the custor channel wing is that compared to a conventional fixed wing aircraft the efficiency will be low at cruise speed. I cant help thinking also that landing may be a problem because the channel wing depends on the induced 'wind' velocity of the prop. While this is fine for take off when the props are producing lots of thrust, on landing with the the engines throttled back little 'wind' would be created and therefore little lift produced. The solution may actually be to land with lots of power at high alpha but i can see that this may be a tricky ballancing act in practice.

[nmasters]

As far as I know there were only three. The CCW-5 was called that because it was a 5 place, not because it was the fifth in series

The CCW-1 was built in 1942. It had two 75hp Lycomings, I don't know how much it weighed so I can't estimate w/lb. It had wing stubs outboard of the channels that the ailerons were on. The military looked at it but decided they didn't want it.

The CCW-2 used a stripped down Taylor J-2 fuselage and apparently the same engines as the CCW-1. The J-2 used a single 65 hp Lycoming O-145 engine. I can't image that Custer's wing would have been lighter than the J-2's straight wing. I'm guessing that the CCW-1 and -2 had nearly three times as much power as similar conventional airplanes.

The CCW-5 was built on the Baumann Brigadier fuselage and had two 275 hp Lycomings. The production Brigadier had two 170 hp Continental O-300s. Since there obviously would have been a weight gain from the 90 degree bends in the wings It may have needed the extra power the just to maintain the same power to weight ratio of the brigadier but I doubt it. As Jetplaneflyer said, it's basically similar to a blown flap but less efficient. Custer was just turning extra horse power into static lift and claiming greater cruise efficiency. The channel wing probably did cruise at a lower percentage of throttle than the Brigadier but since the engines were bigger they produced more power per percent of throttle setting. The fact is that a wing with all those corners has more drag than a flat wing producing the same lift.



And your statement about his personality (http://www.airspacemag.com/issues/2007/april-may/lunch-with-willard.php) isn't what people who actually did business with him say. Now who's talkn' crap? :rolleyes:

--Norm

You guys are postulating instead of researching.

Custer made 5 different prototypes (that I know of), and they all flew beyond anyone's expectations, (though controls had to be sorted out since ailerons don't work at zero airspeed). The reason the plane never went into production isn't because it didn't work... it worked exceptionally well. The problem was bad timing and bad politics. Some guy named Sikorsky was promoting a new invention called the "helicopter" at the same time that Custer was promoting the CCW... and Sikorsky had better political connections and was more business-savvy. Custer, on the other hand, was a grumpy old fart. A major manufacturer offered to buy his design but Custer wouldn't sell unless he got to lead the R&D department... egos flared and he lost the offer. Doesn't change the fact that the plane flew well and had incredible amounts of lift per horsepower.

Sort of like Edison and Tesla... everyone knows Edison created the lightbulb, but few people remember that Tesla invented alternating current, AC motors, radio, microwaves, laid the groundwork for quantum physics, ion propulsion, the list goes on (he could even light up a field of light bulbs with no wires... wireless lighting!)-- he was "brighter" than 100 Edisons, but because he wasn't a a good salesman he died penniless and has since almost been forgotten.

I digress...

Anyway... yes, the plane was designed to be SuperSTOL, not VTOL, though it would hover in a nose-up attitude if tethered to a pole. The nose up attitude does have to do with balancing prop thrust with the wing lift...

I just have to comment on this :
"Given enough watts per pound anything is capable of VTO. The channel wing worked (not well but it did work) but didn't have any practical application. Nothing wrong with building dumb things as long as you don't delude yourself into believing that you're you're investigating the secrets of the universe. It's fun to make obsolete technology work bu it's just play"

Bullcrap.

It's worth noting that the CCW produces more lift per horsepower than any "conventional" aircraft to date, while retaining the same cruising capabilities (speed, duration, ceiling) of similarly sized and powered aircraft. Landing was just the same as taking off... slow airspeed, short runway, high-alpha approach. There is no STOL aircraft built today that can beat the lift-per horsepower... the channel is just so much more efficient than a conventional wing. There is video on YouTube of an early prototype in flight. The short take-off is truly amazing.

[nmasters]

So I just have to ask the question, in a world where the cost of fuel to payload is so important, why aren't there any flying today?

I can't believe it's just because of patents.

Any patents would have expired years ago

[nmasters]

Ha, found it! (http://www.custerchannelwing.com/04_facts.html)
It weighed 1375 lb. That works out to 78 Watts per pound. As it happens a few months ago I figured out the w/lb at gross weight of several GA airplanes. They are:
BD-17.............. 48-85 w/lb
Piper J-3 Cub.... 44 w/lb
PA-18 Supercub 68 w/lb
RV-7A............. 87-115 w/lb
CH-701 .......... 58 w/lb
Mooney M20J .. 58 w/lb
C-130H .......... 66 w/lb

So, proportionately, the CCW-2 had more power than a fully loaded C-130. I would expect such a power loading to either be a STOL or a pocket rocket. I ounce saw an empty C-130 take off in 400 feet and the BD-17, RV-7 and Mooney are all fast planes

[markschaffin]

Some reasons you don't see this concept in use:
1. Certification. With so much of your lift dependent on your thrust, how will you handle/certify an engine out condition? Dead stick? With conventional twins you can still fly with one engine. With rotorcraft you can autorotate. Without some form of coupling the props I don't see how you could balance this plane. Don't forget, folks, if you can't get it certified, you can't sell it.
2. Pitching moment. Sure you get a lot of lift, but you also get a larger nose down pitching moment that has to be countered by the tail. Furthermore, you are carrying this pitching moment around for the entire flight, not just take off and landing. I believe the early NACA reports documented this.
3. Cruise. Once you are off the ground, you can't dump the unneeded high lift. The spanloading on a CW will not lend itself to being efficient in cruise. Unless you aren't going very far, why would you want to fly with your high lift system always deployed?
4. Structural concerns. We don't build many planes with 90 degree turns in the spars for good reasons. Every additional pound of structure is one pound of fuel or payload you can't carry.
5. Prop loading. With the prop located over the wing, it will experience unsteady loading due to the nonuniform flow field. This could cause additional stress on the prop leading to either heavier props and/or more stringent inspections and almost certainly increased costs.
6. Customers. Are there really that many? There are a lot of interesting ideas out there that never make it into production. The marketplace generally gets it right. An often overlooked rule of engineering is that if the product (and engineers design products) isn't financially workable, it isn't good engineering.

During my days at NASA I did work on a small project that looked at this concept with trailing edge blowing. The TE blowing was intended to vector the prop thrust. I've read some of the early NACA/Army wind tunnel reports. In general, they were not very favorable of the project. Call that politics if you want, but there are serious issues with the concept that I believe would keep it from ever making it marketable.

[coosbaylumber]

Well, that makes more sence to me, than the theories about secret, supressed or Hidden items. I wonder what the the estimated daily operation costs were going to be? Mainly baseed upon fuel mileage of the overpowered engines. We can't blame the Gov't on everything.

And want to quibble about one other point, is that I think there were several single engine aircraft constructed in the 1930's. More than the quantity noted here.

Wm.