ajcoholic

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Yup, happens with the digital camera, unlike the film camera that gets a blurry prop.

I have started cutting off the corners, gluing blocks of balsa to the side and bottom sheeting and rounding the corners off. Its starting to look like a Seneca!

AJC

ajcoholic

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Here's what it looks like taking shape after a bit tonight.... SEXY isnt it?! OK, its still boxy but it should look nice when all the fuse curves are done...

AJC

ajcoholic

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I keep plugging away a little at a time...

Tonight more fuse work. Bottom is sheeted and shaped, now installing the formers and hopefully this weekend I will get the control rods installed so I can close up the fuse next week.

The elevator WILL be full flying, as on the full size bird. I am going to make up a pivot with music wire and brass tubing, and the control horn will be inside the fuse. Trying to keep it neat and tidy...

The fellow holding the plane is my friend Dan, he taught me a lot about modelling when I was in my early teens and he was about my age (early 30's).... he just got back into the hobby last year after a 15 year lay-off

AJC

matchlessaero

AJ, your project is coming along beautifully..... Keep the pictures coming....

Andrew

Hi Andrew --

It's looking REALLY good!!!

I'm quite interested in your stabilator approach (lots of pics, please) -- I plan to do the same using a CF tube thru an aluminum bushing -- the CF tubing will also double as a full width spar for the elevator. With the VolksPlane, the pivot point is actually on the very end of the fuselage and I'm a little worried about torsion with the stabilator. The rudder is also full flying, but its pivot point is somewhat forward. My plans are to use the same approach -- CF tube in aluminum bushings -- but I think I will be able to use an internal horn.

Regards,

the "other" Andrew

ajcoholic

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Thanks Matchless, I am more excited on this plane than on any other for some time. Its nice working on a new creation, and no real plans to go by (at least I think its nice ) and free to make changes as I go along.

As for the pivots, Andrew, I know the pivot for the elevator on this plane should be at the 25 -26% point back from the LE. But its a constant chord surface, no sweep or taper. I think for a swept surface you have to find the MAC, and take 25% back from there, then draw your "hinge - line" through the wing. You want it to be just slightly aerodynamically stable, ie, when it flying freely the surface, once deflected should JUST try and return to neutral, if the pivot it too far forward it will require more force to hold it defected, and if it is too far back, it will "grab" and posibly try and go further deflected.

Carbon should be more than strong enough for the spar in your application IMO.

AJC

combatpigg

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Hi AJC! Looks like it might fly if strap on a JATO! What diameter hardware do you figure you'll use for the pivot?

ajcoholic

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1/8th ID K&S brass tubing for pivot with 1/8th music wire for the part that gets glued to the spar, and a wheel collar will be in the center with an arm soldered to it. I will have a straight run to the servo, for a hopefully clean and slop free installation. I have to reinforce the tubing mount area a bit with some ply near the rear.

I think I will have to make the elevator now, and install it before I finish the fuse. Once I close it up, its not going to be able to access the interior near the back.

AJC

DICKEYBIRD

REALLY lookin' good AJ! You're moving along VERY quickly....1 of the benefits of a CAD-less process.

I don't have any scientific calculations to help you with but my one foray into the world of stabilators was almost a disaster. I used the S.W.A.G method of setting the stabilator travel; used way too much and MAN, that thing was a wild ride! Didn't have a dual rate TX and ended up flying it using the trim slider on the maiden. It was a 500 sq. in. slope soarer and if memory serves, I had to reduce it to about 1/8" to 3/16" travel. After that it was a sweetheart.

ajcoholic

My Feedback: (10)

I guess since the area acting on the air is so much larger - you dont need nearly as much throw - right? I will take that into consideration when setting up my bird. I usually have a ahbit of too much throw, will have to force myself to go easy..

I have triple rates on my transmitter and use them. I have saved my *** a few times, after taking off on high, and like you say finding out in a hurry that was WAY too much throw!

I was thinking about 1/8 to 3/16th (measured at the trailing edge) would be lots... what do you think? The stab is 3.5inches wide by about 15 inches span if I remember correctly...

AJC

combatpigg

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HI AJC! DB's right about stabilator sensitivity. I think 1/4" up and 1/4" down will be flyable. Test fly on the ground by holding the model gently at the CG, full power, and have a helper wiggle the stick to see what the reaction is. This is a crude test, but you could experiment with various amounts of throw to see what the difference is while holding the model. I also like ANDREWS' idea about using a larger diameter CF tube, it could be filled with dowel and cross drilled for the attachment points. There are probably many proven designs that the JET JOCKS and THE GLIDER BOYS have executed that I need to look at. Every stabilator that I've ever done ended up like a CHINESE PUZZLE! Having a setup where the elevator halves plug in to the torque tube[after they're covered and finished] seems like the best way to go.

ajcoholic

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OK, I am currently fighting a cold (or the flu, dont know but it hit me today... ) but I thought I better get going on the tail of my plane - its not going to build itself!

I framed up the stabilator, it is 14" span by 3 3/8" chord. Symmetrical airfoil shape.

To do the pivot, I ended up reinforcing the inside of the fuse sides with 1/8 birch ply, and drilled a hole to pass some 1/8" brass tubing through. The tubing is actually two pieces, with a gap in the middle. Thats where the control horn will attach.

There is then a piece of 3/32 music wire 4" long, that goes through the tubing (which I have glued in place). The stab has a groove I cut with the dremel and sits down on the music wire. When I am ready to final assemble, I will CA or epoxy the stab. onto the wire permanently, after covering. It will make a super pivot, and slop free. I am happy with the result.

Here are some pics!

AJC

combatpigg

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HI AJC! You're making good steady progress! Looks like about a pound of wood so far? I didn't know cold germs could survive up where you live this time of year!

MR Flyer57

Really good looking work AJ,
I am worried about the amount of throw that the elevator will need. With the whole appendage moving it will be very slight.
I will be very easy to over control and snap with a full flying elevator. You mentioned in an earlier post that the full size plane has the same elevator system, but I have never seen such a thing short of a military fighter.
MR Flyer57

ajcoholic

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Actually, the entire airframe with the two servos in the wing currently weigh only 10 ounces. I am pretty sure my target weight of 24 oz or under is going to be acheivable.

As for the throw, I stated I will try about 1/8 to 3/16th up/down for starters, with my triple rates set for less throw in case thats too much.

I am not worried about it, please dont be either

AJC

LoneRanger

My Feedback: (1)

yeah, with full flying Stab you wont need much at all throw wise-

looking realy great though! hehe

considering some of us aint even started! LOL



L.R.

BMatthews

Gliders with full flying stabs typically use between + 3/16 to 1/4.

She's lookin' real fine there Andrew. I think we may need to form a special category just for you in the next contest..... or at least give you a starting vote deficit just to give the others a fighting chance....

ajcoholic

My Feedback: (10)

Bruce, thanks for that info - since gliders have a bit longer fuse (generally) than the Seneca therefore a longer moment arm, I should need more or less throw you think??? (I am guessing a bit more since the same deflection further from the "pivot point" (cg) should provide a stronger force - or I am backwards... - if I start with 1/4" I should be in the safe zone. I can allways set one rate higher and one lower than that, and I am pretty good at controlling "out of control" planes... heh heh

I didnt do anything today on the plane, I had 4 diesel conversion heads to make and I helped my buddy convert a 30cc weedwacker motor for him 1/4 scale Taylorcraft... busy day!

Tomorrow I am hoping to finish the stab control, and close up the fuse and maybe start the rudder...

AJC

Andrew

Go with less (or triple rate it) -- if compared to a glider. Its true that the glider would require less force, but the shorter tail moment of the Seneca will make it much more responsive. If you think of the elevator movement being similar to prop pitch, then the elevator on both the glider and Seneca would have the same vertical movement as both planes moved forward a foot, given the same deflection, elevator size, etc.. If the elevator lifted the tail 1" on both planes, the pitch change would be greater for shorter tail moments. Taken to extremes, compare a long tailed glider to a SIG Wonder or Lanier Shrike. Raise the glider tail an inch and get a 5 degree pitch down. Do the same for the 1/2A Shrike and get a 20 degree pitch down.

OTOH, I've been mixed up before .....[sm=confused.gif] Since the VP Sportster also has a flying tail, I've got to deal with the same decision.

the "other" Andrew

BMatthews

In thinking about this a bit more if you consider that regular arrangements are just variable camber and angle of attack wings then if you match the trailing edge LINEAR travel of your full flying stab with the regular arrangement all should be well. Note that we are matching up the vertical travel at the trailing edge and not the angles. So if a regular elevator would use 1/4 inch of travel to either side then the full flying stabilator should use the same. It's the angle of attack of the overall stabilizer that counts and not the control surface itself. At least that's my opinion and I'm sticking to it....

The gliders often don't use much travel because they are usually set up with a close to critical rearward CG for flying efficiency reasons. But this means they don't need much elevator control authourity to have good effect hence the misconception that full flying tails don't need as much throw as measured at the trailing edges.

Other Andrew. Shorter tail moments actually make it less effective. The shorter moment arm has less leverage. But this can be confused by the fact that shorter fuselages often have less weight so they don't have as much resistance to acceleration from the control forces. In the case of the Seneca I suspect the short moment is cancelled out by the larger stabilator.

Even control line stunt models are using longer tail moments and smaller stabilizers these days. Not by much granted but if you compare them to the very short coupled models of the past it's very noticable.

ajcoholic

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Well, its sunday evening and I am feeling like CRAP... colds are not fun

But, something possessed me to get out of bed, and down to the shop today for some building. Works better than chicken soup for making me feel a whole lot better!

A few large Tim Horten's coffee's didnt hurt either You Canadian boys know what I mean

I managed to finish the stabilator linkage and servo install. I have used as I did in the wing, sullivan small cable in the plastic sheath. I rigged up a sweet link on the pivot wire, basically a wheel collar into which I placed a 4-40 bolt that captured an aileron linkage (plastic). Then I secured the cable all along the way to the servo, and the works is easy to move, yet slop free and shopudl work beautifully.

Then I started to sheet the fuselage, and managed to finish cutting the windows and reinforcing the sheeting between the windows, before I had to call it a day.

Here are some pics!

AJC

ajcoholic

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And here is the fuse more or less finished minus final sanding...

I re-weighed the airframe today, after the sheeting was done, with the three servos installed, it is only 10.5 ounces.... so far so good....

AJC

lear31A

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I have been following this thread in amazement-GREAT JOB! It looks like you could put two tails on it and make it a tail dragger and it would look just like a Beech 18..

ajcoholic

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Thanks Lear, I am having a lot of fun with it.

Other than a few aerobatic planes (a Giles and an Extra) I have never done anything "scale" before, even stand wayoff'ish scale like this one. But I must say it is a lot different feeling than just a sport model, as I am continually looking at pictures of the full size bird I printed off the net for inspiration and guidance. Usually when I am scratch building I dont really worry too much what the end result will be, as it is an original. But I am trying to get this to actually look 1/2 way decent like a Seneca!

I think tonight may be the rudder, and/or landing gear. This thing needs some legs!

AJC

ajcoholic

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Tonight I made the landing gear and fin & rudder, and fit the moveable surfaces and hinges.

The mains I bent up from 3/32 music wire, and glued them on. Straight forward. I am using 1 1/2 lightweight foam wheels. They are close enough to scale size.

For the nose gear, I used a left over tailwheel wire from a 40 size ARF! It was perfect size for the Seneca, with a coiled leg. It was 3/32 diameter also. I made a trick bracket for it to mount to the bulkhead and also made it "sprung", with 3/8ths of an inch travel. For those rough runways.. The nose wheel is also the same size as the mains.

The rudder and fin I made up and glued onto the fuse. Pretty straight forward job, bt adds a lot to the look.

I forgot my camera at home, and will take some pics tomorrow and post at lunch....

I just have to install the rudder servo, and run the control cable and steering cable, and then onto the nacelles this weekend.... its all coming together!

AJC