Increasing Wing Loading
 

Hey Guys.....need your input here. I'm just in beginning to build Adrian Page's GeeBee R2 kit. I'm want to put a radial in it and am leaning towards a Saito 170. The only down side is this. The wing loading in it's original form works out to 25 oz per sw ft. If I put a radial in it'll jump to 30 to 31 oz per sq ft. I would like your opinions on how you think this is gonna fly. I'm pretty much thinkin like a lawn dart huh?


Let me know,


Thanks

Scott J. Wolke

Increasing Wing Loading
 

You'll have only two problems.
Takeoff and landing.
If it gets in the air, it will fly OK.
Let it accelerate a LOT on the ground.
If it gets in the air, it will have to land.
It will come down like a brick.
Let it.
If you try to land it slowly, it WILL tipstall!

Increasing Wing Loading
 

31 oz/ft/ft sounds like what you'd find in a warbird.

I noticed greatplanes GeeBee has a loading 36 oz/ft/ft, and it is only 60 size plane. My understanding is that a larger plane should be able to handle a relatively larger wing loading and still fly well. Relative to Great Planes' ARF, your situation does't seem so bad.

What does the cubic wing loading work out to?

Cubic wing loading = (weight in ounces)^3/ (wing area in sqft)^2

7 or less is a considered a "floater"
8 to 9 a good flier, still in aerobatic territory
beyond that is pushing into heavy flier territory


Refer to this thread: http://www.rcuniverse.com/rcarchive/19/2002/06/1/31859

Increasing Wing Loading
 

Buy a LOT of props! I've never seen a Gee-Bee fly (except for Delmar's). Groundloops and turnovers for the models.
Short coupled, narrow gear, high ground angle... not a good combination.

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Oh great! Yet ANOTHER "expert" who has never flown a model Gee Bee willing to give advice.

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In addition to Gee Bees, add T-6s, A-26s, P-38s, Mosquitos, Comets, P-40s... all are poor fliers at best, and short-lived. Seldom see one a year old.
High wing loadings demand a lot of expertise, especially when landing. Any attempt to 3-point usually tip-stalls the poor thing.
I has spoke! :D

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Adrian,
Your comment (and your icon) seem to suggest you have considerable experience with this plane. Yet you offer no help other than to heckle others who are kind enough to try and help this fellow.

Thanks to Jim and Paul for taking time to write.

Tom

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Three different G Bees at our field; all fly very well.
I do not use the same formulae for Wing volume loading; I believe that the correct one is Weight in Ounces divided by Wing area in square feet raised to the 1.5 power. And yes, a 7 is a floater and anything less than 10 can be a good flyer. Anything over a 10 starts to have the characteristics of a lead sled.

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"Anything over a 10 starts to have the characteristics of a lead sled"

Sheesh, at 13.+ it's no wonder the Extra I fly now flies like crap.

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I tend to agree with the need for speed. I have seen Delmar fly his GeeBee and was very impressed. I seemed to remember though, reading about it later, that he had to be very aware of the airplanes speed and not get tooooo pushy near the limits. He also has the skills to recognize when and where those limits are.

I have a GeeBee on a much smaller scale, http://www.fan-tasticmodels.com/, that is quite nice. However the wing loading is really really light. I had seen video of the original model flying and was impressed. It is neat to see an airplane that you expect to be a tiger turn out to be a *****cat. You get all the looks and thrill of the airplane without any of the crummy flying characteristics of the big one - yes I said crummy.

Adrain - I have seen a couple of model GeeBees at scale meets, flyins, etc., but they were never flown. There was probably a reason for that.

There is a difference between having the beast strapped to your butt, with the flying ability of Delmar Benjamin producing a great show and having a model whose characteristics seriously degrade with small scale being flown from the side of a runway with visual feedback only.

A lot of the bad press that GeeBee models get is from a combination of the scale effect, being too heavy due to structure in the large fuselage and not having the CG correctly located along with not very precise radio equipment (at least in the old days) and imprecise piloting techniques.

But note that something like my old CG Falcon or Curare doesn't suffer from the same press as a GeeBee . Why? My guess is that all of the above comments about the GeeBee would also fit a discription of the Falcon - except the relatively poor aerodynamics of the GeeBee has been replaced with good aerodynamics. The Curare is a good design for everything including speed while being absolutely fine flying at all corners of the envelope.

Even though the GeeBee can be made to fly and fly nicely, it is not a good design in the forgiveness department. That doesn't make it bad for its intended purpose or mean that a model can't be flown. It doesn't mean that it is a model that can't be loved (people like bulldogs afterall). It just means that it is not very forgiving - a good airplane is forgiving, the GeeBee isn't.

It doesn't take an expert to work that out.

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The Gee Bees have excellent aerodynamics. If I understand your emails above you have never even seen a model Gee Bee fly, let alone flown one yourself. How could you consider yourself an expert on their flight characteristics if you've never flown one? Fly one of mine that was built properly, then tell me they don't fly well.

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.
Obviously you read more into messages than is there.
I have seen several model Gee-Bees attempt to fly. All failed. This is due to the narrow landing gear track, and the steep ground angle. About the same reasom my Fokker Dr-1 is a handful to takeoff. Similar configurations behave similarly.
That's the "expertise" I pass on.
I can't comment on the flight characteristics of the model, having never seen a model Gee-Bee fly, but if the c.g. is in the proper position, the control surfaces don't move too much, and there's no warps, once the thing is in the air, it should fly well.
I've seen Delmar fly the real one.. It flies well, but he's a superior pilot!
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Planes I've flown (and photographed while flying them) in 2003...
http://www.angelfire.com/indie/aeros...ultipix-01.htm

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Adrain, the GeeBee configuration doesn't have excellent aerodynamic characteristics. As we have seen even bull dogs can be loved and the GeeBee is loveable in the same kind of way. However, you have to allow yourself a scale that has the worst airplane on one end and the best on the other. The best (excellent aerodynamics) airplane is probably a cross between a F-15, SR-71, 3 meter RC glider and a TOC type 30+ percent airplane. The worst is a lot of the bricks I tried to fly 35 years ago.

Once you have established the poor and excellent ranges then fit the airplanes you are aware of in between those ranges. Do it dispassionately and without bias and make full use of the total range between poor and excellent. The GeeBee is not in the excellent range.

A good thing about aerodynamics is that it is possible to predict the flying qualities of airplanes before they are built. There are manual methods available (which I hated to do) and also computer simulations that make this possible. What I have learned from these tools is that the human brain is also a good predicter of these kinds of qualitites. When our brain indicates that the airplanes is going to have problems it isn't wrong too often. It can be yes, but not all that often.

In addition to those things that Paul mentioned is the effect that the monster fuselage has on the directional stability as well as possibility of blanking out the horizontal tail in certain maneuvers. A rudder mated to the end of the fuselage is not as good as a rudder mated to a fixed surface (I know I am exaggerating but it is almost that bad). The GeeBee is a compromise of wrapping a fuselage around a big motor. If it were even in the "good" category I would think that we would see more of that configuration flying today than we do. There weren't a lot of manufacturers line up to copy the configuration. Why not? If I remember Delmar's writings on the airpane there were a lot of things that he had to do very carefully.

The one model GeeBee that I have direct knowledge of besides my little one is the Great Planes version. My friend flew it once, seemed eternally grateful when it landed OK, said never again, and hung it up in his shop for a display model. This is a person that is reasonablely experienced. He did not have nice to things to say about it. It flew, yes. Did it fly well, maybe, he might have been having an off day or the CG was wrong (but I doubt it) - after all it did fly and land successfully.

Whether or not the GeeBee configuration is going to work well depends on the wing loading involved. My little model is a feather and is great, the Great Planes version is heavy and apparently wasn't. A larger model with light wing loading is going to fly better and may be fun to fly. I will probably build one of the Great Planes GeeBees my self some day because I like the unique look and I enjoy a challenge as well as the next guy.

But excellent, maybe not.

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Ben,

I can respect that. I still say the aerodynamics are sound, but I have only flown Gee Bees with low wing loadings.

Adrian

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I've always loved the GeeBee since the first time I saw it at Oskosh Air Venture ( I have been there every year since I was born except 2, am 26 now ) and love to see it fly. One thing you will notice watching him fly the full scale one is that with those little stubs for wings he NEVER EVER pulls on it very hard. Only rolls and inverted passes, knife edge... never seen a loop or anything that would put more than about 1.5 G's on it for fear of a high speed stall, if that doesnt say anything about the wing loading of the full scale one I dont know what does :D Beautiful airplane though, every aspect of it... planes dont come much more wicked than that big radial with wings. Getting bolted in doesnt leave much hope in the event of a "mishap" though [&o]

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In his book, Delmar says he has no intentions of ever looping it!

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I guess I don't really see why you couldn't loop it unless the wing loading is out of sight - I guess if it flies at an extreme angle of attack at one g then maybe.......

Certainly if the fuselage lift will allow true knife edge flight the wings should be able to haul themselves around!

My little one will loop but that is comparing cake and oranges.

RE: Increasing Wing Loading
 

I can assure you that model Gee Bees loop very nicely. I do avalanches with mine. If you get the CG too far back or use too much elevator throw they will snap out of the top of the loop....(same as any plane) Just reduce the elevator throw until it stops the snap at full deflection. The Gee Bees I fly have 25 to 30 oz wing loading.
The knife edge is amazing. It only requires the wings to keep it from spinning wildly about its axis...and for landing and take off.:D
BTW the rudder is very powerful and requires only a small amount of throw. Too much rudder in knife edge will cause the plane to sink. Too much angle of attack I suppose. Or not enough power.
To get an idea of the Gee Bees aerobatic potential you might want to compare the tail moments of the Gee Bee with modern aerobatic planes like the Extra and Sukhoi. I think you will be suprised at just how close they are. Most of this type of plane seem to have about one wing cord between the stab and TE of the wing. Pitch stability is dependent on other factors anyway. Flying wings come to mind.
Ben, is that your sons Cub in the AMA mag page 66?

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I was refering to the full scale Gee Bee R1, as far as looping that goes the loop would have to be so big that you would run the risk of running out of airspeed durring the 2nd quarter of the loop if making it large enough to keep the G's under about 1.5 to stay on the safe side of a high speed stall. The full scale planes touch-down speed on a landing is around 95-100mph, not terrible by todays standards of jets and high performance, high altitude propeller driven planes, but when you consider that landing speed is for a 17ft long plane with a 25ft wingspan it is quite insane. Weighing in fully fueled at around 3900lbs with those little wings the loading is around 37lbs per sq. ft. which is extremely high given the small amount of wing area carrying that amount of weight. To make a comparison, a full scale Cessna 150 has a 33ft wingspan, weighs 1600lbs fully loaded, lands at 45mph and has a wing loading of 10.2lbs per square foot. The old rule of "With enough power, anything will fly..." is the key to the GeeBee R1's flying ability. A tiny plane with a supercharged, 800hp Pratt and Whitney "Wasp" radial... it flys, but only safely in an extremely limited flight envelope which includes high speed, low G maneuvers. Many pilots who raced one more than a couple times were buried in them :eek:

Brian

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Adrain, that Cub belongs to my nephew, Mark. He is the son of my brother (the black sheep of the family although he worked at World Engines for 20+ years while it was in Cincinnati). He is now advertising manager for Model Aviation and an avid model builder/flyer. I was his mechanic this summer at the scale part of the nats. He has sworn off Cubs. Wind got us the first day and literally blew it over on landing. He rebuilt that night and the next day flew fine except that the motor would cut out about 2/3 of the way through a flight. It turns out that there was a tiny little slit in the fuel tank caused by the crash and it was spraying fuel inside the airplane with great abandon. He put two or three flights on it before taking the wing off. It is now a soggy mass of balsa held together by Monocote. It looks good but don't squeeze it or the juices will come out!

Speaking of hard to fly airplanes. I have had 3 RC Cubs over my lifetime. One was a big fiberglass fuse beast (my brother gave it to me after he couldn't get it off the ground) whose only claim to fame (for me at least) was its ability to ground loop! I am an experienced modeler and aero eng. for a living and I couldn't make it get off the ground. Tried wheel toe in and CG adjustments but to no avail. Finally one of the ground loops cracked the aft fuselage and I threw it away. The second Cub is still flying and is a really overweight World Engines model made of mostly plywood. It is overengined (blame that on me) and flies like a pylon racer with no low speed ability, it will also snap with too much elevator throw even at high speed. Definitely not Cublike. The third is a little 7 ounce Herr Cub converted to RC. Ailerons, elevator, rudder, motor. It flies very nicely and the ailerons do work.

On snapping out of a loop. I have a GWS Zero and Cosair that will do that at a given elevator setting. It is interesting to watch them go from a great looking loop to snaping. It is not a wide overlap. Just a few degrees of elevator.

It certainly points out that the same design can have many manifestations depending on builder and a lot of things. I certainly agree about the moments of the GeeBee being adequate. I worked that out years ago when I first read about it. There is a tendency to mentally switch over the the body diameter as a reference when it gets fat enough.

Brian's notes about the landing speeds kinda put it into perspective. Can you imagine having that monster nose up in front of you at those landing speeds while landing on a grass field! The pilots certainly have my respect but don't you know that they were having more fun in those few hours lapping the other airplanes in a race than most of us have in a lifetime. Of course landing might have scared a few years off their life expectancy.

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Only one pilot was ever killed in a R series Gee Bee...Russell boardman in the R1.

I find it hard to believe that a plylon racer would only pull 1.5 g's in a race. I can't find any info on how many G's were pulled in a race by a Gee Bee. Where did you get that spec? I did read that they were designed to withstand 10 g's.

As I understand it, the R1 had a large fuel capacity to allow it to get to the city that was sponsoring the race. It would only carry enough fuel during the race to complete the task at hand....typically 50 or 60 gallons. That would lower the wing loading to about 25 lbs. per square foot. The R2 held 300 gallons but it was designed for cross country racing where high G manouvers would not be an issue. It would only carry a small amount of fuel in a pylon race. I believe Delmar Benjamin flew his R2 in the same manner.

I have read more than one account of these planes being "floaters" on landing. The models certainly bear this out if they are built light. I suspect that the huge amount of wing area in the fuselage give it some sort of ground effect.

Adrian

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I agree...take a really nice flying model plane and move the CG back about 4" and see what happens.:D

Adrian

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When Delmar published his book several years ago, he mentioned his plane has more flight time on it than ALL the Gee-Bees ever made accumulated! I expect he knows the plane. :)
On its first flight he took it inverted it handles so well. The secret to his success is the c.g., I believe. It's a tad forward of the specified location. (And his inborn caution to NOT be a smoking hole in the ground.)
I would expect models of the Gee-Bee to fly well, once the difficult part of ground-handling is overcome. No reason why they shouldn't. But short-coupled steep ground-angle models can be prop eaters and wingtip scuffers. I've had and seen too many of them to want to go thru that "learning experience" frequently!

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Ben,

It just sank in where I knew the name Mark Lanterman from. He's the guy I place my adds with at Model Aviation Magazine. That's been driving me crazy! I new I knew the name! BTW,
I checked out your photography links (That's my other hobby)....nice work.

Adrian

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Adrian - Not exact G load numbers, just using a light load as an example to prove the point, I'm not sure how many G's it can handle before snapping out. Been a few years but I talked to the full scale pilot at Oshkosh for about 10 minutes by the airplane and I asked about his flying style and accelerated stalls, he said the less you pull on it, the safer you are... he said accelerated stalls are easy to get into, hence the light G demo's, no loops, no pulling turns. The airframe was stress proven to 12 positive G's on the ground as a test to see how well the plane was built, which it passed... it is an unbelievably strong airframe for the era, but there's no way it would ever see anything close to that in the air as it would stall long before that from lack of wing area.

I am looking forwards to flying one on G2 when Addons 5 is available :D Just to see the plane in action on my moniter should keep me happy for a while :D