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RE: WACO YMF
If your fuse is nose down with the wings at zero incidence then you have positive incidence with the fuse level. That's the same problem I had. The fuse (crutch) should be level first and then check/set the wing incidence. That's why I had to raise the trailing edge of the wing to get zero. I'm sure the plane will fly like that but I wanted to get mine exactly right. The full size WACO flies nose down at cruise. Of course it all depends how the pilot trims it. Flying 'tail down' is not fuel efficient in the full size as already touched on by KHODGES. STICKBUILDER- What about all this all this noise about incidences realative to the crutch? Seems you're the only one here who has experience with this bird. |
RE: WACO YMF
I have managed to reach:
2 degrees positive on the stab, engine is exactly 0 degrees and the fuse is dead level (although still in its humble position;)) nose down (normal) The left side of the lower wing is exactly 0 degrees and the right side is roughly 3/4 of a degree positive inboard o degrees from the aileron to the tip. I can not for the life of me get the right side down to 0. No warp at all when I rest the wing on the bench and measure, wing is square in the fuse. I am going to allow myself to be happy with this setup and cover. If the humidity is different on the day I setup before paint, well we'll see :D If I am going to suffer at all with this setup (top wing will be exact) I would like to hear about it! |
RE: WACO YMF
ORIGINAL: damifino The full size WACO flies nose down at cruise. Of course it all depends how the pilot trims it. Flying 'tail down' is not fuel efficient in the full size as already touched on by KHODGES. STICKBUILDER- What about all this all this noise about incidences realative to the crutch? Seems you're the only one here who has experience with this bird. Mine all seemed to fly nose down at cruise. I want the plane level at cruise, therefore the exercise with the adjustable stab. My wings are at 0 deg relative the crutch. the leading edge of the h-stab will be up 2 deg to start, and we will see where I wind up with the setting when all is said and done. I want the model to fly at this angle of attack without adding trim to the elevator. Of course, I don't want the plane to balloon under power either, so that will probably require a stab change for high throttle, of course that is a bump with the index finger on the flap dial. I watched a real YMF take off from the local airport yesterday evening. His climb-out was pretty steep, but you could see when he trimmed the bird out. Dead level, and not laboring to fly. Dang, It sounds pretty too. Bill, AMA 4720 WACO Brotherhood #1 |
RE: WACO YMF
[link]http://www.airliners.net/open.file/1083388/M/[/link]
What flying attitude does this look like?? Notice the postion of the foreward h-stab carry-through and the incidence of the H-stab. |
RE: WACO YMF
Looks to me like it's flying level. The H-stab seems to have positive incidence as the model calls for.
Bill Hogue WACO Brotherhood #21 |
RE: WACO YMF
Hughes500E
Are you talking about your fuse being nose down relative to the stab? Otherwise, I don't understand how it can be dead level and nose down at the same time. If the crutch is level then the fuse is level. The crutch is parallel to the thrust line on the plans, therefore that is the datum line and all incidences should be relative to this line. BTW, I wouldn't worry about those small differences between wing panels at this point. You can 'warp' them even during the covering as long as they aren't too far out. Bill Hogue WACO Brotherhood #21 |
RE: WACO YMF
According to my level (bubble level glued right to the crutch) I am dead level. According to my eye, the fuse will be flying nose down. Maybe it's just the taper in the forward fuselage that makes it look like it's nosing down
[:-] |
RE: WACO YMF
I agree with you.
I printed out the side view (from pdf file) of the pica waco fuselage print on 11x17 and held it up in front of me with the crutch level. No doubt about it, with the crutch level it looks like it is flying nose down. I think your right, it may be that forward taper in the fuselage that makes it look that way:eek:. However, since the wing is parallel to the crutch, and at moderate speeds, isn't the angle of attack of the wing always a little positive anyway? That would make it look like it is flying level. I do not know how common this is in powered craft, but I flew alot of sailplanes and they all fly nose down in level flight ( and no, it is not because a sailplane is always decending). It is very noticable in sailplanes. ORIGINAL: Hughes500E According to my level (bubble level glued right to the crutch) I am dead level. According to my eye, the fuse will be flying nose down. Maybe it's just the taper in the forward fuselage that makes it look like it's nosing down [:-] |
RE: WACO YMF
1 Attachment(s)
This is my 1/6th Dave Platt Waco in flight. We can see it is flying level but have a look at the elevator :D
I never built this one, I was just fortunate enough to own and fly it. There are a lot of variables but that is a lot of elevator! I must say, I had my hands full a few times [X(] |
RE: WACO YMF
They say a picture is worth a thousand words, but that picture raises a thousand questions. I can see that while flying level the wings are at positive attack, just like I thought. If that plane is at sustained level flight, then it would indicate that the stab needs to be a negative incidence (leading edge down), not positive.
That picture is very confusing to me. It does reinforce my desire to get rid of the wrap around style elevator though. It just looks aerodynamically dirty. My waco is not scale anyway. Heck, my pica kit wasnt scale either come to think of it. ORIGINAL: Hughes500E This is my 1/6th Dave Platt Waco in flight. We can see it is flying level but have a look at the elevator :D I never built this one, I was just fortunate enough to own and fly it. There are a lot of variables but that is a lot of elevator! I must say, I had my hands full a few times [X(] |
RE: WACO YMF
Now you know why I'm asking so many questions and revisiting :D
It was indeed level flight. The builder was watching as I passed by, this is when they took the pictures. CofG could of been nose heavy is the first thing that came to my mind. My knowledge back then was extremely limited, gaining everyday but I could not comment on the exact setup. What ya mean dirty [X(] |
RE: WACO YMF
1 Attachment(s)
BVW Update.
Fuselage work is progressing, along with the tail feathers, and I've started to "build" the bottom wing so I can accurately create F21. So far, everything is fitting pretty well. I've had to tweak a few former outlines here and there to get them to flow together from above to below the crutch. I'm still debating whether or not to create laser-cuttable files when I'm done. Would anyone be interested in that? I might just cut all the parts by hand... Chris |
RE: WACO YMF
ORIGINAL: Hughes500E This is my 1/6th Dave Platt Waco in flight. We can see it is flying level but have a look at the elevator :D I never built this one, I was just fortunate enough to own and fly it. There are a lot of variables but that is a lot of elevator! I must say, I had my hands full a few times [X(] |
RE: WACO YMF
ORIGINAL: Skinny Bob Looking at the picture tells me that the CG was to far forward or the top wing incidence was negative. Ether condition would require up elevator to maintain level flight. Bill, AMA 4720 WACO Brotherhood #1 |
RE: WACO YMF
I might have to build another one [X(]
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RE: WACO YMF
I think the variable incidence H-stab is a good idea. I would like to incorporate that in mine also.
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RE: WACO YMF
1 Attachment(s)
Hey
Has anyone seen this website on the Proctor YMF-5 ? Looks like a nice setup. They make a 1/3 kit 118" Here is the link: http://www.proctor-enterprises.com/p...SPECIFICATIONS Another with scale flying wires http://bredavik.se/flyingwire/wire_gallery2.htm kit cutters http://www.kitcutters.com/Pep/PepYMF35WACO.htm Larry |
RE: WACO YMF
If that plane is at sustained level flight, then it would indicate that the stab needs to be a negative incidence (leading edge down), not positive. That picture is very confusing to me. It does reinforce my desire to get rid of the wrap around style elevator though. It just looks aerodynamically dirty You guys are beginning to confuse me! In the picture; Maybe the engine's thrust line is way off, perhaps there was a tail wind pushing it, wing incidences screwed up, why would a WACO need negative H-stab incidence? If all I had to go on was this photograph, I'd honestly say the bird's wing incidences were off. Make drastic changes to a proven model? I wouldn't do that based on the evidence presented. The variable incidence H-stab exercise is not intended to be a band-aid for a poorly aligned model, it is to help us fly it in a more scale-like manner, to take off and climb realistically, to present landing approaches that will be (hopefully) beautiful, and yes, to fly at a pitch attitude that is pleasing to the eye. It is my honest, informed opinion that if built according to the plans, aligned properly and balanced correctly this bird will fly right. Build it with 2+ on the H-stab and 0 degrees fixed for the bottom wing and you've got the easy option of adjusting the top wing incidence if needed as flight testing progresses. My goal is to achieve decent pitch attitude at cruise speed with the H-stab at or close to 2+ degrees and with neutral elevator. I feel adjusting the top wing incidence is the proper way to achieve this and may also help eliminate the model's known tendancy to 'quit flying' abruptly at slow speed. |
RE: WACO YMF
I don't think any of us want to "change anything" we are just in pursuit of the best setup!
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RE: WACO YMF
OK, if no one else is going to ask I guess I have too. In order to compare my planes with yours and try to make sense of this, what is the crutch. thanks, Jim #9
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RE: WACO YMF
Jim,
If you look at the top view on the plans, the crutch is the basic frame (F-17A,B,C, the 3/16" x 3/8" crutch "stringers" and F-26) you attach the bulkheads to. From the side, the crutch connects the tail section to the front section (F-1, 2 and F-4T & B) and is the reference (datum) line for the wing/stab incidences and thrust line. See ChrisMH's post # 1537, first picture, the 2 stringers shown are part of the crutch. |
RE: WACO YMF
I think you guys are getting too wound up about this flight atitude/trimming issue. You can't force these things to fly `at this pitch attitude' at some cruise speed `cause that just isn't the way it works. If you have ever flown full size you will know that to fly at a straight and level cruise speed you first set the horizon at the right place with elevator, wait until the ASI tells you that you are at the aispeed you want, set the correct RPM (power) then trim the stick forces away with the elevator trim. The angle the fuselage flys at is set by the relationship between the rigged angle of the wing/fuselage, and the angle of attack required to provide enough lift AT THAT AIRSPEED to maintain height. If you want to fly faster, then the new trimmed attitude will be `tail high' (less AOA), conversly if you fly slower then the attitude will be tail low (more AOA). The trick with your model is to choose the correct rigging angle of the wing to the fuselage to give the right flight attitude at your chosen cruise airspeed. Tailplane trim is only an airspeed control, not an attitude control. If you now fly your model faster, you will have to trim nose down to stay S&L (tail high) etc, etc. A heavy model with the same rigging angles will seem to fly tail low compared to a light version with the same set up. I prefer to set my models up to fly S&L at around 50% throttle barrel movement. This way to climb I merely open the throttle, and to descend just close the throttle a bit. This eliminates, for me, the necessity to re-trim for differing airspeeds as I aint going far/long enough to need to worry about stick forces present at cruise for hours at a time...:-)
Evan, WB#12. |
RE: WACO YMF
ORIGINAL: pimmnz I think you guys are getting too wound up about this flight atitude/trimming issue. You can't force these things to fly `at this pitch attitude' at some cruise speed `cause that just isn't the way it works. If you have ever flown full size you will know that to fly at a straight and level cruise speed you first set the horizon at the right place with elevator, wait until the ASI tells you that you are at the aispeed you want, set the correct RPM (power) then trim the stick forces away with the elevator trim. The angle the fuselage flys at is set by the relationship between the rigged angle of the wing/fuselage, and the angle of attack required to provide enough lift AT THAT AIRSPEED to maintain height. If you want to fly faster, then the new trimmed attitude will be `tail high' (less AOA), conversly if you fly slower then the attitude will be tail low (more AOA). The trick with your model is to choose the correct rigging angle of the wing to the fuselage to give the right flight attitude at your chosen cruise airspeed. Tailplane trim is only an airspeed control, not an attitude control. If you now fly your model faster, you will have to trim nose down to stay S&L (tail high) etc, etc. A heavy model with the same rigging angles will seem to fly tail low compared to a light version with the same set up. I prefer to set my models up to fly S&L at around 50% throttle barrel movement. This way to climb I merely open the throttle, and to descend just close the throttle a bit. This eliminates, for me, the necessity to re-trim for differing airspeeds as I aint going far/long enough to need to worry about stick forces present at cruise for hours at a time...:-) Evan, WB#12. |
RE: WACO YMF
Wound up! Wound Up! Whose Wound Up:D?!Remember that I said that picture would raise a thousand questions.
About Drag I think this is the best discussion of the whole thread, passions are high, and people are thinking hard. I am finding out a whole lot of new info and also learning about the personalities of you all. Good Stuff. I enjoy this incidence dialogue better than reading a whole page of threads on non-Waco issues[:'(].There has been allot of that on this thread. So far I have been treated with good info from both an aeronautic engineer and a full scale pilot. Without this over the top discussion on incidence I would not have heard from either of those gents. I was very interested in damifino's thought that the low speed "stop flying tendency" of this plane could be the wing incidence. Anyway, about drag, I change allot of stuff on my planes. It makes my model personal and I enjoy it. Just because this is a bipe does not mean that I give up all considerations on parasitic drag or induced drag. If drag is a throw away issue on bipes, why does the real one have a cowl and wheel pants? To reduce drag I'm only using one set of flying wires and no wires on the tail. I also left off those crossed sticks between the landing gear legs. Those forward points on the wrap around elevator create allot of vortex turbulence at both high and low speeds when not aligned flat to the stab. I probably would not go out of the way to get rid of them but I have to strip the covering on my tail feathers to redo my ribs anyway, it might be a good time to go with the typical stab, elevator layout. |
RE: WACO YMF
ORIGINAL: ronj10 why does the real one have a cowl and wheel pants? To reduce drag I'm only using one set of flying wires and no wires on the tail. I also left off those crossed sticks between the landing gear legs. Those forward points on the wrap around elevator create allot of vortex turbulence at both high and low speeds when not aligned flat to the stab. I probably would not go out of the way to get rid of them but I have to strip the covering on my tail feathers to redo my ribs anyway, it might be a good time to go with the typical stab, elevator layout. 2. You may find the model is short lived without the tail braces., and the, "Crossed Sticks" are again part of the WACO thing. 3. As to what you refer to as a wrap around elevator, this is actually a counter balanced elevator, and is again part of the WACO shape. It appears to me that you are not going to wind up with a WACO YMF, but rather a *******ized WACO (excuse the expression) and it will probably not fly as the YMF should. Ron, this is not a put down, but if you were going to do this to the model, why not start with something else? There are tons of bipes out there that will accomplish what you are wanting to do with far less headaches involved. Just wondering why go through all the gyrations and not wind up with a recognizable plane, nor one that flys within the scale envelope? :D Bill, AMA 4720 WACO Brotherhood #1 |
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