Composite-Arf 33% Gee Bee R2 - First Flight - Pics - Videos - L@@K
10-26-2013, 07:05 AM
#1601
Both Steve and Tom, the owner of the GB I flew, have made the small modification to tie the two belly bolts together by means of a custom metal part. This distributes the load of the bolts and shares it while relieving the plywood of its torsional load in its stock configuration. I spotted this issue when inspecting the plane and commented that with a positive G load the bolts that tie down the wires to the belly are pulling sideways on blind nuts in wood. Bad idea because this relies on the strength of the wood laminate to hold not the hardware so much. The solution is a simple plate made of aluminum or steel with the bolt pattern. Tom made an inside and outside set of plates. Now the load from the wires is distributed through metal parts and the weak link is eliminated.
Were going back out to fly this Sunday. Ill try to have more video this time too.
Were going back out to fly this Sunday. Ill try to have more video this time too.
10-26-2013, 07:20 AM
#1602
While there is certainly nothing wrong with taking extra precautions, adding reinforcement where you find it necessary, I can tell you that using the stock (4mm?) belly bolts, I have not experienced ANY observable wear and tear or signs of loosening after 50 flights. I like the idea of a 'spreader bar,' but I see no compelling reason for it.
Where I see the most wear is in the wing spars where the flying wire bolts pass. These holes tend to elongate over time due to both the flight loads and flying wire vibrations. Eventually, they will require a brass sleeve be inserted into the wood.
Where I see the most wear is in the wing spars where the flying wire bolts pass. These holes tend to elongate over time due to both the flight loads and flying wire vibrations. Eventually, they will require a brass sleeve be inserted into the wood.
11-24-2013, 06:48 PM
#1607
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I need your input folks.
From my own plans I am building a 33% highly scaled 1933 model R1. I wouldn't enter scale competition, but as fidelity is, to a point, important to me, dimensional accuracy, rivets, panel lines, and mechanical function will be closely adhered to.
Then there is the fin offset.
My research tells me it was designed into the R series to offset the torque of the P&W Wasp engines. I will be installing only an Evo 260 radial or a Moki 250 radial, the torque from either of which a craft of this size can easily handle.
I don't want to offset the fin! Should I, shouldn't I?
What sayest all of you fine gents?
Jules
From my own plans I am building a 33% highly scaled 1933 model R1. I wouldn't enter scale competition, but as fidelity is, to a point, important to me, dimensional accuracy, rivets, panel lines, and mechanical function will be closely adhered to.
Then there is the fin offset.
My research tells me it was designed into the R series to offset the torque of the P&W Wasp engines. I will be installing only an Evo 260 radial or a Moki 250 radial, the torque from either of which a craft of this size can easily handle.
I don't want to offset the fin! Should I, shouldn't I?
What sayest all of you fine gents?
Jules
11-25-2013, 07:46 AM
#1609
I need your input folks.
From my own plans I am building a 33% highly scaled 1933 model R1. I wouldn't enter scale competition, but as fidelity is, to a point, important to me, dimensional accuracy, rivets, panel lines, and mechanical function will be closely adhered to.
Then there is the fin offset.
My research tells me it was designed into the R series to offset the torque of the P&W Wasp engines. I will be installing only an Evo 260 radial or a Moki 250 radial, the torque from either of which a craft of this size can easily handle.
I don't want to offset the fin! Should I, shouldn't I?
What sayest all of you fine gents?
Jules
From my own plans I am building a 33% highly scaled 1933 model R1. I wouldn't enter scale competition, but as fidelity is, to a point, important to me, dimensional accuracy, rivets, panel lines, and mechanical function will be closely adhered to.
Then there is the fin offset.
My research tells me it was designed into the R series to offset the torque of the P&W Wasp engines. I will be installing only an Evo 260 radial or a Moki 250 radial, the torque from either of which a craft of this size can easily handle.
I don't want to offset the fin! Should I, shouldn't I?
What sayest all of you fine gents?
Jules
For scale accuracy, I would say YES to the right fin offset, especially with a high torque engine like the Moki 250 spinning a prop with lots of pitch. But the key is to make sure you do NOT put any airfoil into the fin. It should be FLAT on both the left and right sides so that the only affect is to make the aft end of the aircraft go left (nose go right) at ALL SPEEDS.
Any airfoil built into your fin will create unwanted flight deviations that are speed-dependent.
You may also notice that the AMOUNT of right fin offset can vary depending upon your scale reference.
Having stood literally 6 inches behind Delmar’s R2 at Fof (with Hannes L), I can tell you the amount of right fin is far more than what is shown on the Henry Haffke 3-view (top view). So the question is: WHICH Gee Bee will you replicate?
I have flown the Gee Bee R2 both with and with out right fin and my preference is WITH OUT. But this does require just a hint more of right rudder input.
IF you are building the plane for utmost in scale accuracy and will power it with a big radial, then I would build a “hybrid” right fin offset shown on the Haffke 3-view, making sure that the portion above the cockpit/turtledeck is FLAT on both sides, exactly like Delmar’s. That’s my $ 0.02
Btw: you will also need some engine right thrust! (I have flown the Gee Bee w and w/o and believe me, you NEED right engine offset!)
11-25-2013, 07:55 AM
#1610
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Thank you Steve & Richard. Any other inputs welcome!
Richard,
Why did you prefer flying the 0 offset fin Gee Bee? I presume that was your .25 scale beauty shown on your video?
Jules
Richard,
Why did you prefer flying the 0 offset fin Gee Bee? I presume that was your .25 scale beauty shown on your video?
Jules
11-25-2013, 09:07 AM
#1611
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After reading what I wrote , I see my brain and my one finger typing method did not keep up ( LOL )
I wanted to say the Moki's have Low RPM's but HIGH torque .
I just don't know if the offset in the rudder is needed.
Richard has more time flying the Gee Bee than I do, so I would probably go with his recommendations.
steve
I wanted to say the Moki's have Low RPM's but HIGH torque .
I just don't know if the offset in the rudder is needed.
Richard has more time flying the Gee Bee than I do, so I would probably go with his recommendations.
steve
11-25-2013, 04:20 PM
#1614
I have flown both the CARF and my 25% w/o right fin. Once the proper right rudder is trimmed, the airplane tracks like an arrow at any speed, although acceleration (throttling up) will still result in some ‘crabbing’ to the left IF the aircraft is not absolutely level. This is P-factor and you aren’t going to eliminate it.
Again I must stress that right fin offset is probably OK, but I cannot say that with absolute certainty because I have not flown this Gee Bee with and with-out a right fin with NO airfoil so that I could compare apples to apples.
Unfortunately, the CARF Gee Bee mold creates a fin with an airfoil that does the exact opposite of what you want it to do! I am hopeful Andreas will correct this if and when he remakes the Gee Bee molds!!
Btw: just for grins and the sake of heart palpitations, I have flown the CARF with NO engine right thrust… nightmare!
12-23-2013, 09:04 AM
#1616
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Sir, I would like to know where you ordered your Gee Bee kit from ? I bought one used but never flown and the flying wires on L wing came loose. Pretty much totaled.
La
Larry
La
Larry
12-28-2013, 07:09 PM
#1622
In a perfect world you solve this problem in a wind tunnel because at this scale these decisions make a real difference. An airfoil will be more efficient and less critical of AOA and airspeeds. A flat fin will be more critical of its installed AOA which will be more turbulent in flight.
The Gee Bee has such a short fuse with so much surface area it presents some interesting flight characteristics. If you take advantage of an airfoil then for what its worth its effect can be designed for a broader speed range than a flat sided fin. That would the sweet spot to shoot for. This is in fact what full scale planes like a Messerschmitt 109 employ to compensate in flight. This relieves the pilot of having to trim the rudder as much in flight.
Id go with an airfoil and use the best technical scale documentation you have as to its angle and hopefully airfoil cross section. If nothing else use the same offset angle and then smooth out the shape to the trailing edge of the fin. This would be a guesstimated airfoil but at least it will be more efficient and smooth the flow to the rudder. In cross section it should resemble a semi symmetrical airfoil and the bottom should face the right side from the top view.
Post pics or start a thread, it would be interesting to see your solution and how it works.
The Gee Bee has such a short fuse with so much surface area it presents some interesting flight characteristics. If you take advantage of an airfoil then for what its worth its effect can be designed for a broader speed range than a flat sided fin. That would the sweet spot to shoot for. This is in fact what full scale planes like a Messerschmitt 109 employ to compensate in flight. This relieves the pilot of having to trim the rudder as much in flight.
Id go with an airfoil and use the best technical scale documentation you have as to its angle and hopefully airfoil cross section. If nothing else use the same offset angle and then smooth out the shape to the trailing edge of the fin. This would be a guesstimated airfoil but at least it will be more efficient and smooth the flow to the rudder. In cross section it should resemble a semi symmetrical airfoil and the bottom should face the right side from the top view.
Post pics or start a thread, it would be interesting to see your solution and how it works.
12-30-2013, 06:04 PM
#1623
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Well guys I flew my Gee Bee again yesterday and have come to the conclusion it is a real pig of a thing in the air. It will not track in a straight line no matter how much I use rudder mix or manual input on the sticks. With the rudder mix turned off it crabs to the left pretty bad, with the mix on it is better but will still not track straight and then needs left aileron to compensate for the right rudder. When trying to line up for a straight run even with the mix it wants to creep left even if the plane is pointing right. I must of tried 4 or 5 straight runs down the strip from the left only to end up with the plane banked over on its right side just to stop it moving further away. Coming in from the right it wants to keep moving towards me even if the plane is banked hard over left with a fair amount of elevator fed in. I have watched pretty much all the CARF R2 videos publicly available and my plane certainly does not behave like the ones seen online.
I now believe there is truly something not right with the setup and I have been through everything less the engine dome and its offset. I expected a handful with this plane but not something that is comparable to a shopping trolley with two bad wheels. The plane was purchased mostly built so the engine dome is one thing I had no control over the fitting which is why I am thinking it’s not set right.
On the previous maiden it had trouble tracking straight and wanting to yaw left. It had some right rudder mix in on that flight which did not have a lot of effect. After that flight I went through the plane. Doubled checked the, incidence, dihedral, throws, C.G, and mixed in more rudder movement with the throttle. This flight I was a lot less nervous and had time to think about what was going on and it was not pleasurable trying to keep this beast looking respectable in flight.
The landing was also not so good, it took five or six attempts then on the last it clipped a bit of a rough patch at speed and went over on its back. It sure damaged the ego but the planes relatively fine. It didn’t help that on the finals it still likes to creep left even working all the surfaces to try to get it to track straight on approach.
I am determined to get it sorted so any input is welcome.
Jaz
I now believe there is truly something not right with the setup and I have been through everything less the engine dome and its offset. I expected a handful with this plane but not something that is comparable to a shopping trolley with two bad wheels. The plane was purchased mostly built so the engine dome is one thing I had no control over the fitting which is why I am thinking it’s not set right.
On the previous maiden it had trouble tracking straight and wanting to yaw left. It had some right rudder mix in on that flight which did not have a lot of effect. After that flight I went through the plane. Doubled checked the, incidence, dihedral, throws, C.G, and mixed in more rudder movement with the throttle. This flight I was a lot less nervous and had time to think about what was going on and it was not pleasurable trying to keep this beast looking respectable in flight.
The landing was also not so good, it took five or six attempts then on the last it clipped a bit of a rough patch at speed and went over on its back. It sure damaged the ego but the planes relatively fine. It didn’t help that on the finals it still likes to creep left even working all the surfaces to try to get it to track straight on approach.
I am determined to get it sorted so any input is welcome.
Jaz
12-31-2013, 11:50 AM
#1624
Well guys I flew my Gee Bee again yesterday and have come to the conclusion it is a real pig of a thing in the air. It will not track in a straight line no matter how much I use rudder mix or manual input on the sticks. With the rudder mix turned off it crabs to the left pretty bad, with the mix on it is better but will still not track straight and then needs left aileron to compensate for the right rudder. When trying to line up for a straight run even with the mix it wants to creep left even if the plane is pointing right. I must of tried 4 or 5 straight runs down the strip from the left only to end up with the plane banked over on its right side just to stop it moving further away. Coming in from the right it wants to keep moving towards me even if the plane is banked hard over left with a fair amount of elevator fed in. I have watched pretty much all the CARF R2 videos publicly available and my plane certainly does not behave like the ones seen online.
I now believe there is truly something not right with the setup and I have been through everything less the engine dome and its offset. I expected a handful with this plane but not something that is comparable to a shopping trolley with two bad wheels. The plane was purchased mostly built so the engine dome is one thing I had no control over the fitting which is why I am thinking it’s not set right.
On the previous maiden it had trouble tracking straight and wanting to yaw left. It had some right rudder mix in on that flight which did not have a lot of effect. After that flight I went through the plane. Doubled checked the, incidence, dihedral, throws, C.G, and mixed in more rudder movement with the throttle. This flight I was a lot less nervous and had time to think about what was going on and it was not pleasurable trying to keep this beast looking respectable in flight.
The landing was also not so good, it took five or six attempts then on the last it clipped a bit of a rough patch at speed and went over on its back. It sure damaged the ego but the planes relatively fine. It didn’t help that on the finals it still likes to creep left even working all the surfaces to try to get it to track straight on approach.
I am determined to get it sorted so any input is welcome.
Jaz
I now believe there is truly something not right with the setup and I have been through everything less the engine dome and its offset. I expected a handful with this plane but not something that is comparable to a shopping trolley with two bad wheels. The plane was purchased mostly built so the engine dome is one thing I had no control over the fitting which is why I am thinking it’s not set right.
On the previous maiden it had trouble tracking straight and wanting to yaw left. It had some right rudder mix in on that flight which did not have a lot of effect. After that flight I went through the plane. Doubled checked the, incidence, dihedral, throws, C.G, and mixed in more rudder movement with the throttle. This flight I was a lot less nervous and had time to think about what was going on and it was not pleasurable trying to keep this beast looking respectable in flight.
The landing was also not so good, it took five or six attempts then on the last it clipped a bit of a rough patch at speed and went over on its back. It sure damaged the ego but the planes relatively fine. It didn’t help that on the finals it still likes to creep left even working all the surfaces to try to get it to track straight on approach.
I am determined to get it sorted so any input is welcome.
Jaz
Either I was flying your plane… or you were flying mine on Sunday, as I posted 3 horrendous flights with my “newly redesigned and lighter and more scale Gee Bee”…
What you describe is identical in every respect to what I experienced on Sunday, as well as on MANY other previous flights prior to my recent changes. My plane handled exactly the same as when I had switched from a DA150 to a DA100 (in my first GB) and the CG was at 80mm.
What is worse (for me) is that all the work I had to do to compensate for the removal of nearly 4 pounds of engine in the nose (3W157 to a DA120), paid NO dividends – the handling actually went in the opposite direction! Disappointing?? You bet!!
Post mortem, it has been suggested that perhaps what WAS the accepted CG (73mm – 76mm) is no longer valid on my aircraft, as the nose has grown in length by 5cm (scale cowl). This makes sense and is something I will have to correct and test.
However, as you did not lengthen your Gee Bee, I have to assume you are balancing it within the accepted “norm?” If so, I can only attribute the ill-handling to what I have always suspected on this airplane, and that is the twisted vertical fin. It isn’t so much the fact that the fin LE is offset left (for yaw to the right); it is more that the fin has an airfoil that imposes the exact opposite effect of the offset. Stand over the tail and look down at it and you will see what I mean. With the unwanted and non-scale addition of an airfoil, the vertical fin’s effect on the aircraft is totally speed-dependent and (IMHO) results in an UN trimmable flying thing (like your shopping cart analogy).
That said, there ARE pilots who have managed to program the perfect level of rudder mixing with the throttle such that they have been able to neutralize the fin’s “enigmatic” affects
This requires patience, many flights, and the ability to analyze exactly what is happening with the aircraft’s yaw at every speed; remembering what you want to change in the pits, re-testing, WHILE keeping your airplane in one piece throughout the trial and error testing flights… no small feat!!However, even WITH the perfect amount of mix, what then results is a Gee Bee which is constantly exhibiting instability in pitch, as rudder deflections create negative pitch reactions (nose down). I was once sure this was simply an aerodynamic anomaly unique to the Gee Bee… but have come to believe this is actually gyroscopic procession – exactly what happens with cyclic inputs on a helicopter – caused by the Gee Bee’s short tail moment’s lack of leverage.
- Gyroscopic procession is the imposition of force 90 degrees from the axis of force, which is why changes in yaw result in the nose pitching down. I can only assume that IF our engines were spinning clockwise, the affect would be the opposite, with yaw deflections creating a nose-up reaction. And that, boys and girls, is about the extent of my aerodynamic understanding!
Since you stated that you have re-checked everything, what is your current CG? And how are you checking it? Do you have something accurate like an EZ Balancer?