Dash7ATP

OK, let's try this again.

Still getting the ERRORmessage.

rccrasher65

My Feedback: (35)

Dan. Thanks for all the info. I have all the necessary shop equipment, I've been a woodworker for 27 years, and still have a complete shop. Not that my wife lets me make the dust like I used too!! Thanks again for all your help. George

Dash7ATP

OK, Dan , my photos uploaded this time.One of these gives a good shot of the rear of the wing fairing from the rear. It might be helpful as well.

It is easy to see how the wires enter the wing at the root. It appears we have little choice but to attach them to a bracket similar to what you have done at the N-strut fittings. The one above the gear is another matter altogether. I'm thinkingt of a half bulkhead with a continous aluminum piecegoing from one side to the other. It wouldn't have to be very large.

Joe

FMBB

Hi Tom,

your AoAs of the wings and elevator a definitely wrong. The lower wing should have an AoA of 0° degrees which is correct, the upper should have minus 1° to 2° and the elevator should have an AoA of plus 2° (which is nose up). The CG should be about 20mm in front of the aft center strut assuming the strut has been installed according to my design. Also it seems to me a bit heavy normally with your installed equipment it should weigh in at about 23Kgs which should be about 51pds. But the 6 additional pds do not have any influence to the flight performance only the min. speed will be higher but that's ok. You might not get her to a stand still in the air during a slight windy day.

I hope this helps. I hope your Waco has the original air foil I am using respectively provided in the kit. Believe me its worth to repair the ship if all is correct it has a second to none flight performance and very easy to fly with no bad habits.

Do not hesitate to contact me if you have some more questions. I do not provide plans without kit but if you need you may order spare parts.

KR
Peter

Dash7ATP

This is a general question regarding the measured Angle of Attack (AoA).  The AoA is normally measured along the chord line (most forward LE point to the Trailing Edge). I think this is common knowledge. However, on the Pica kit, it appears to be measured along the line of the flat bottomed airfoil. I realize we are talking about relative differences, but the thin stab is a little different with a almost triangular airfoil.   What should we be looking for when setting up our models. The chord line (of the wing) is already several degrees positive with respect to the flat bottom.

Joe

ceije

jmdunstan, i'm building a Barth 1/4 scale and had sent the prebent wire gear to bruce at century jet and they reproduced it for me. if you go far enough back in the forum within the last 150 pages i posted pictures. his assembly is super can't tell how well it works i'm not even close to finished yet. bruce will set the strut preasure to whatever weight you give him. ho yes, the gear is to scale and if you decide to go with it bruce needs demensions for the size required for your bird (a little leg work on your part) expect about a mont or a little longer delivery time. have fun and enjoy...

chris melhus, ceije 196

ceije

dash7atp,

not trying to stick up for century jet but 90% of his landing gear are retracts and require air kits so i think to make life easy he puts air with all of his gears.

chris melhus,ceije 196

Dash7ATP

.............which of course, he charges you for even though you can't use it .

jmdunstan

I just received a Pica 1/5 scale kit I bought through a want ad I posted on RCU.  They are still out there, and this one turned out to be in perfect condition.  Rather than the die-crushed 1/8" lite ply wing ribs I expected, the kit contains perfectly die-cut 1/8" medium balsa ribs.  I wonder if this says something about the vintage of this kit.  The very beat-up box is white and blue, but it did an excellent job of protecting its contents.

I am currently corresponding with both Abell Hobbies about bent aluminum struts and with Bruce Sanders of Century Jet about oleo struts (with or without an air system).  I have not received any response to my earlier request to "khodges" for the drawing/pattern/template that "Jay" used to produce produce his struts.  I will share the outcome of my exchanges with Abell and CJ.

Jim

tmac48

PAGE 571 They really look great, would be interested in the price for a set to suit the 1/3 scale Barth kit.

pimmnz

Dash, you can't measure AOA's, that is defined as the angle between the wing chord line and the Free Stream Direction, can only be measured while in flight, and is constantly changing, specially with models...but you knew that. The RIGGING angles you are measuring must be related to something, though, and you are being quoted the chord line angles as they relate to each other. So, what you now have to do is to block the fuselage up to the visual angle you would like to see it in the air. Rig the lower wing to about 1deg positive, that is the chord line will be about 1 degree positive to the table top the airplane is sitting on. Now rig the other surfaces to the bottom wing as advised, ie the tailplane at 2.5 deg positive and the upper wing at 0.0 to 1.0 deg negative, all in relation to the table top. These are the riggers angles, as would be specified in the rigging chapters of the maintenance manual. All relate to the section chord line.
Evan, WB #12.

Dash7ATP

Last 15 Posts - reverse chronological order pimmnz, Of course you are correct with respect to the the AoA. It relates to the difference between the relative wind and the chord line. That term was used in a previous post by FMBB in a discussion of someone elses WACO that apparently was set-up incorrectly. In my post Ishould have used the term incidence, which is the relationship between the chord line/s and the main referrence line for the aircraft. My plans mention a zero degree incidence for the bottom wing, but ti shows that angle as being measured using the flat bottom of the wing rather than the actual chord line. That being the case, the actual angle of incidence would be approximately 2 to 3 degrees positive (I haven't actually measured the difference between the chord line and the bottom of the wing). Iguess it doesn't really matter as long as you keep to the same measuring system (chord line vs the bottom surfaceof the wing) and keep the angular differances the same relative to each surface. JOe

pimmnz

Yep, you got it. But the bottom wing being '2 to 3 deg positive at the chord line'...positive to what? I know we bandy words around, but with this stuff we need to be fairly concise, and meanings need to be clear. If you are using a datum, then you need to specify it. Rigging manuals will tell you where to put the level, and how to level the airplane to start checking the rig. 737's used to have a plumb bob and cross in the centre wheel bay, and you jacked and leveled the airplane by adjusting it until the bob pointed at the centre of the cross. Fokkers had a line marked on the fuselage. I mentioned that you could use the surface the model was sitting on. Too often people complain that their model flies 'tail low' and start complaining that the balance is in the wrong place...Consider that, in flight at 'cruise' speed' the wings will be at some AOA which provides the same lift as the model weighs. The fuselage is just along for the ride. Hence my request, 'put the fuselage at the attitude you want to see it at in flight', then rig so that you have a degree or two on the bottom wing, and zero or just a bit on the top. I rig mine to be the same incidence, and have no complaints from me or anyone else who has flown them, to taste then. Rig the tail to the bottom wing as advised. This will ensure that there will be a speed, hopefully less than at full RPM, where the model will just sustain level flight, 'zero trim speed'. Less RPM and it will come down, without trim change, and more, and it will go up, without trim change. Just like the real thing, which is what we are trying to replicate, and it's a very relaxing way to fly them.
Evan, WB #12.

nine o nine

My Feedback: (1)

You're right Evan. What we're talking about as "rigging angles" are simply angles of incidence based on a datum line...usually the top fuselage longeron. Mitch

FMBB

Hi gents,

it´s rather easy. On my Waco you have the bars inside the fuselage just going from the front to the aft a bit below the cut out for the cockpit. So this main bar is your reference plain you are looking for. This bars (rh and lh) should be in parallel to your building board. Now you may start to measure the angle of the wings. Measure just before where the ailerons start (looking from the fuselage to the wing tip) as the measurement close to the fuselage where the short ribs are will of course give you to a wrong result. Do the same for the upper wing. Once again the angles should be 0° degrees for the lower wing and minus 1° to minus 2° degrees for the upper wing. The horizontal stab should have plus 2° which is leading edge higher than trailing edge. This will give you the best flight performance. These are the angles I am recommending also in the building instructions, which was the result of more than 15 years of flight experience with my Waco. All over the world people did build it like that since than and no one ever claimed for problems with the models flight performance.


Kr
Peter Brother #170

Blackwidow

Thanks for the help Peter!

Dash7ATP

Peter, after the previous posts regarding this, it seems the issus I have is what referfance line on the wing are we using for this. Typically on everything Ihave ever flown full size or models, this referance line on the wing has been the chord line. On my plans (Pica KIt) It shows zero degrees with the angle being measured from the flat bottom of the wing. That may be what the designer used for his set-up, but the incidence is not actually zero degrees from the fuselege referance line.The bottom of the wing may be at zero degrees. Iguess as long as we all arrive at the same setting , it's all Ok.

If Iset my wings at zero degrees based on the chord line using an incidence meter, with the fuselege reference line at zero degrees, I would not arrive at the same settings. Iassume that since the wing is flat bottomed, that was easy to use for setup. It was theterms being used that I was questioning

Joe

ceije

dash, sorry i've read about enough , obvisouly there is something you don't seem to understand about this means of setup or your trying to read more into the process then there is. best bet pay attention.

ceije 196

pimmnz

Quite right Dash, if you are using an incidence meter you will have to change the reference angles. The easiest way would be to use the original plan and draw the chord line on the bottom wing, measure it against an obvious datum, such as the upper longeron, as suggested, then measure the rest as Peter has described. The end result will still be the same, but you can use the meter on all surfaces. Personally I don't like using a bit of structure as a reference as it is often hidden by the covering, and I use a table top or other flat surface I can put the model on. That way, so long as I support the model the same way I can take direct measurements from the reference surface and use them any time to check the rig, after heavy landings, repairs, overhauls etc, and be sure that it will fly just as before. Whatever method you use just be sure that it is symmetric, ie the same on both sides. That seems to be more important than the actual surface incidences, so far as flying is concerned. By which I mean that a degree off on incidence has much less effect than a degree difference one tip to the other...
Evan, WB #12.

Dash7ATP

Ok, guys, Iguess I"ve stirred this pot about long enough. Do Iunderstand this ? Yes. Iddo know the differences between all of the angles, etc., and Ido know how to set up the model. Ihave been modelingfor about 60 + years, and retired from the airlines with 25,000 hrs +.So yes, Iknow of which Ispeak. My entire problem was with the plans referring to the bottom of the wing as a referance point rather than the chord line. Of course,you MUSThave a point of reference from which to measure. Onthis model, it's the top longeron So long as the bottom of the bottom wing is parallel to that, or to the building surface, It's at the propper incidence.

subject closed???

pimmnz

Yep, beaten it to death...
Evan

acerc

Ahhh come on. Ya'll can stretch it out a couple more page's. It was just getting interesting. LOL

rcjunky67

HEY YA'LL,what's this incedense thingy ya'll keep on talkin bout? can you buy you some at the hobby store, or do you need one of them there mail order catalogs? INCEDENTLY, ain't perspective a b**ch sometimes.DATUMMMM

rcjunky67

hey ace, what major town is Lithia close to? I'm in Belleview, just south of Ocala. just curious...

ckangaroo70

My Feedback: (51)

I am hoping one of you fellows can help me out. I have an Ikon N'West UPF-7 that I finishing up building, but don't have plans for it and I need the CG for it if somebody can help me out there. Thanks