trlambsr

Sure looks like it"s not round to me
TR
Waco Brotherhood # 69

skylarkmk1

TR,

I would cautiously agree with you, since I don’t know the type and/or N-number of that particular of the plane you have shown. The 1987 YMF Classic, NC 14081 is the only Waco I have seen with the round aileron connecting rod, every other Waco that is in the Museum or that attended the Fly In, has had streamlined connecting rods except as noted (SRE, AVN-8).

khodges

My Feedback: (1)

That is a interaileron link on a UPF-7. The giveaway is the squared off rear edge of the cockpit and the horizontal truss member at the bottom of the cabane strut. All the UPF-7's I saw at CCA had streamlined links

I looked through all my YMF pics; like Skylark, almost all I have are the newer Classic/Super, and they all have round links. The couple of pics I have of an original YMF (NC 14132) appears to have a streamlined link. It looks like the forward edge is round, while the trailing portion is tapered, and the heim joints, or whatever, are just slightly offset forward, as they would be if the only streamlining was on the trailing portion of the link.

My guess is that the Classic has the round one just because it's cheaper to make, and streamlining this piece doesn't justify the cost for whatever small aerodynamic benefit it gives. As most of these planes are too new to need restoration, they'd still have what was original to them. Most other airworthy Waco's have been restored to their original specs, which included the airfoiled interlinks.

Hey, John; what can you tell me (and the other Brothers) about the number of existing airworthy SRE's? I was looking at something on the 'net the other day that said something about the yellow/green SRE that we saw as being one of only three still flying. I don't know how up-to-date this statement was. When I think about it, I can think of only one other that I have seen in pictures, the white/red New York News plane.

Jim Henley

Ken,
Do you have any photos of your landing gear legs after you made the last change? Or do you know what post they may be on in this thread? I am looking to add more width to the leading edge of the L/G fairing and to add a little more taper at the rear.
As they say, "imitation is the sincerest form of flattery"
Thanks!

jagnweiner

My Feedback: (1)

Bill-

Of course I'll take your advice. In my case, I'll probably do three tests. The engine is an FA-91S that originally came with the new style (ugly) muffler. I swapped mufflers with an older Saito because the old style will be a better fit. I'll try it with new muffler, old muffler and old muffler with extension. Hopefully the extension won't make much difference, as it will not be very long and the inner diameter will be slightly larger than the ID of the outlet of the exhaust.

khodges

My Feedback: (1)

Jim, I got lots of pics, it's just as easy to re-post them as look them up (and the extra post gets us closer to the 200 page mark)

The first picture is the gear by itself, and I have already cut out the center of the mounting plate to lighten it. The next one shows the gear in place, and the marks show where I will take material out of the legs to lighten it further. Next shows strips of balsa at the leading and trailing edges, to give final profile to the fairing and an attachment point for the balsa skins that will go over the legs. The strips are 5/32"balsa (the gear is 1/8" aluminum. I also cut a 5/32" thick triangular-shaped piece to fit in the cut out portion of the gear legs. Then I sheeted both sides of the gear with 3/32" balsa (I don't know if it mattered, but I ran the grain long ways on the inside of the legs and crossways on the outside). This makes the gear legs a total of 11/32 " thick. I mounted the gear, and cut 1/2" triangle balsa stock to make the transitions to the fuselage, and glued them in place. None of the balsa is actually glued to the aluminum, the triangular piece in the cut out portion of the legs keeps the sheeted portion in place, along with the strips down the leading and trailing edges. There is 1/64" clearance between the balsa and aluminum to allow for flexion, expansion/contraction, etc, so the balsa doesn't split, and the fiberglass also helps. Then I took the gear off and started sanding to shape. The leading edge got rounded off, and the trailing edge is tapered to almost an edge, like a wing. The triangle stock is sanded into a concave curve and the forward edge rounded, trailing edge tapered. You can see in the next photo what I did down at the axle end, just tapered it to the metal. You can also see how I did my wheel pants bracket. After I got it all sanded to final shape (It's not 11/32 thick any more, down to about 9/32), I fiberglassed it with a single layer of 1/2 oz cloth, overlapping at the leading and trailing edges to give it some strength so it doesn't dent as easily from handling, etc. The whole thing after glassing and final sanding weighed 4 oz more than the original stock gear, and is a hell of a lot stronger. The last picture just shows the bottom, with belly pan and struts in place.

Notice also, that when I made the trailing edge strip, I extended the trailing edge back under the leading edge of the bottom wing, and just cut it to fit the curvature of the leading edge where they meet. This is more like the prototype than what the kit shows (at least the ARF)

Jay has the template for this aluminum gear; I won't be so bold as to say he'll be happy to make one for you, but maybe everyone can strike their own deal.

argon622

Tony V. : Maybe there is someone that you know that has a larger pic of the Waco classic logo (black lettering/gold wings). The one you sent me is the correct one but cannot enlarge it clearly.

Best Regards..............BG Brotherhood #48

BigBoy99

Ken,
that looks pretty good, your landing gear solution, l like it.
I´m still considering, to make an independent suspension for my Barth Waco 1/3. The origin plan solution works only,
if both wheels touch together. If a single wheel touches, there´s no suspension.
I want to make , that the spring moves up and down and additionally makes a pivot moving, to equalize the one wheel touch down.
What do you think, does it works?

Bernie

Jim Henley

Thanks Ken, the size stock you used, and the photos, are a huge help. I will post some shots as I get further along with my repair.
Thanks again!

SuperCub Man

argon622 - will these do? You can add colour as you like! If these don't come out good enough over this site, PM me with your e-mail addresss and I will e-mail them to you.

skylarkmk1

Ken,

I took a look at the FAA registry http://registry.faa.gov/aircraftinquiry/defimg.asp and there are only 6 SREs registered with them. They are as listed;

N-Number Ser/Num Location Status

20967 5089 California Revoked
31655 5156 California Valid 1998
1252W 5153 Illinois Valid 2003 (Popular Grove Airmotive)
247E 5081 Louisiana Valid 1977
58785 5155 Louisiana Valid 2004 (attended AWC Fly In)
20961 5086 Missouri Valid 1988

Only one ARE is on the registry;

20953 5080 Wisconsin Valid 2007 (EAA Aviation Foundation)

This is the most current Airworthiness Certificate date, however, it may not reflect the current aircraft configuration. See the FAA site to find out more about the status of a particular plane.

khodges

My Feedback: (1)

BigBoy99, I'm no engineer, but I'm not sure that making the spring assembly swing side-to-side would make any difference in making the suspension work better on a one-wheel touchdown. First, you'd have to have a long slot across the bottom of the fuse to give the spring assembly room to move. Also, as one gear leg moved out (the one touching down) and pulled the spring assembly toward that side, it would pull against the other gear leg, as the struts from the spring assembly to the bottom of the gear legs are the same length and do not extend or collapse. The strut opposite the leg that touches would tend to keep the spring assembly in the same location.

A one-wheel touchdown would impose a vertical force on the gear leg(parallel to the leg itself); the only mechanism that would give shock absorption in this circumstance would be a shock absorber at the end of the gear leg, such as the full scale YMF has, or like the Sierra gear. The struts aren't designed to absorb the landing shock on the full scale, but to prevent the legs from spreading under landing loads or just the weight of the plane. My idea of a spring to allow some "give" is a poor man's way of softening the model's gear a bit while maintaining its ability to support the model, since the wire gear and my design don't have any spring action or shock absorption at the scale location.

And since we're on the subject of shock absorption, I received the Robart tire inserts today, and have been out in the garage playing with them. They are what I thought, a closed-cell foam, like the gray formed pipe insulation you can get at Lowe's. They are cylindrical, and the diameter is the same as the inside of the tire. You remove the tire from the wheel, and stuff the insert into the tire. It is long enough that you have to trim it, and you want to make sure it is stuffed tight and no gap is between the ends, or you'll get a flat spot on the tire which will be softer than the rest of the tire. Screw the wheel halves back together, and you have a much firmer tire. It still has some give that should damp out that initial impact when it touches down, but it is plenty firm to keep the tire from collapsing or going flat under the plane's weight when it is parked. They aren't nearly as hard as my Sullivan tires. Below is a picture of the insert and tire. The small piece is what the cross-section of the insert looks like.

I am confident that these tires, in conjunction with the spring strut on my gear, or the sprung leg on the Sierra gear, will be a definite improvement over what the wire gear can do in giving a damped absorption of landing shock; it won't save a hard landing, though, only practice and technique will do that.

bart5495

Ken
Ok I’ve got a really dumb question concerning the landing gear struts you’re talking about.
If the main struts are mounting to the fuselage without the ability to move or pivot what is the purpose of the inner strut mounted to a spring absorbing shock system?

Thank you

Doug

BH # 11

FMBB

I would not notch the botto of the fuselage toallow the spring to swing aside. If you will do a one wheel landing the piano wire will of course act as a spring and move upwards. The landing force will be distributed also to the center strut and will be be reacted as a vertical force which will load the internal spring and pullout the bolt a bit. Around the center position the wires are not so stiff and give some movement to care also for a one wheel landing.
In case you notch the center you allow the spring to move to rh and lh side. In case of a hard landing the shock load may be so high that it would enlarge the notch. With the current design this is not possible. So I would recommend not to change my design if you do not adapt the soultion of the full scale, which is absorbing the landing shocks close to the wheels.

Peter

Stickbuilder

Doug,

I can answer that one for you. The wire is not rigid. It does have the ability to flex under load. The way the wire is shaped, a hard landing will side load the wire to the point that the gear wants to spread under the load. Using the struts and the compression spring, slows the inertia of the plane trying to collapse the gear, or spreading the gear out. Eventually, the spring reaches full compression, and completely stops the spread of the gear. If you measured the gear tread (distance between the wheels) with no weight on the gear, and then measure the tread with full compression load, you would probably find that the total spread is at least one inch. The struts and spring minimizes the distance that the gear can spread out, and the compression action slows the action down, keeping (hopefully) the gear from completely collapsing. We have all seen models after a hard landing with the gear mangled. this just mitigates the amount of movement.

The Sierra gear will have a shock absorbing unit built into the main gear leg. The top of the gear leg will need to be articulated to allow the shock unit to function correctly. It will still need the struts and compression spring to keep the gear from spreading.

Bill, AMA 4720
WACO Brotherhood #1

Stickbuilder

Still working on the tail group. At least this one won't need to be mounted before the Fuselage is covered (every cloud has a silver lining). All (I hope) the hatches and panels are made, and the installation has been finalized. There is a fairly big one (actually it's two piece) for the tail wheel and the Horizontal stab hardware. I made them from fiberglass, but the cheek hatches are from aluminum. I'm not going to put any cloth on the fuselage, until I hear from Darrell at Sierra Giant Scale. I may go ahead and start on the wing centers while I'm waiting. In fact, if I do the top wing center section, I can finalize the cabane mounting system that Jay (damifino) and I have been working on. It should make the incidence setting easier, and more precise, while gaining a better scale appearence.

Bill, AMA 4720
WACO Brotherhood #1

SuperCub Man

Hey no secrets!! I'm just at that stage now and have put off further work on it until I get the cowl - an excuse to not face the mounting problem!! I have everything scratched together except the landing gear and the cabane system. Any hints???

khodges

My Feedback: (1)

Doug, I think Stickbuilder addressed this fairly well; what I meant when I said that the inner struts don't extend or compress is that they are solid pieces. They just act to transfer the spreading force into a compressing force on the spring assembly. With either the wire gear or my aluminum gear, the shock absorbing ability comes from the gear legs "bending" where they meet the fuselage under the loads impressed on them at touchdown. In the worst scenario, they can completely flatten on a hard enough landing, bending them past their ability to spring back to their original position. The inner struts could be fastened directly to a fixed point on the fuse bottom to prevent this (the other end of course being fastened to the lower main struts), but then the gear would have no ability to give under landing loads. The spring assembly allows for a limited amount of outward movement; as the main struts try to spread, this outward motion is converted to a vertical motion by the inner struts to the spring, which compresses and absorbs the energy of the landing shock, shared by the spring action of the gear legs themselves. Of course, there is a limit as to how much energy it can absorb due to its limited movement, but it should be enough for a "normal" envelope of landing shock. A really botched touch down with heavy loads will exceed the gear's ability to absorb it, but then it would exceed most any other design as well, including the design of the full-scale gear, which the Sierra gear will mimic.

On the Sierra gear (as well as the full scale), the inner struts are firmly attached to the fuse with no spring. The gear is triangulated and rigid. the last section of the bottom of the gear legs, below the attachment of the inner struts, is telescopic and the shock absorption occurs there, as the landing loads cause the sliding sections to telescope on itself, like the shocks on your car.

khodges

My Feedback: (1)

Bill, I have to differ with you on one point above. The top of the gear leg doesn't articulate, all the movement is in the oleo struts. The main legs can't move, as the inner struts are firmly attached both at the base of the main legs and to the triangulated braces at the top. The compression spring at the top of the inner struts is unnecessary.

The difference in the Sierra gear vs the spring strut design is that the wheelbase on the spring strut design gets wider on landing impact, and on the Sierra (and full-scale) it actually decreases; albeit it is a minor change in both cases. See my poor sketches above. These pics are of the scale gear available for the 25% and 33% models, I believe are also made by Sierra.

Stickbuilder

Ken,

I'm talking about where the trunions mount to the plate, and allow the gear to spread. That is what I was talking about as their being articulated. Maybe that was a poor description.

Bill, AMA 4720
WACO Brotherhood #1

Stickbuilder

Instead of using the electrical connectors and soldering them to the cabanes, I am going to shorten the cabane wires, and add an extension that will allow the remaining cabane wires to slip inside one end, and be soldered into position. The other end will be threaded to accept an #8 machine screw. The end of the screw will be blacksmithed to a flat pad that is cross drilled to accept a 4-40 through bolt.

The wing blocks will still use the 4 hardwood blocks. There will be 4 sets of double shear mounts bolted and glued through these hardwood blocks. The double shears will be spaced to allow the blacksmithed ends of the #8 bolts to fit between them, and then be through bolted to the double shears (look at the full scale). This will allow for an almost infinite incidence adjustment, and when you consider that the interplane struts will be mounted in the same way, you will be able to correctly adjust the top wing at 8 different points, simply by screwing the blacksmithed end in or out.

Bill, AMA 4720
WACO Brotherhood #1

skylarkmk1

Ken,

The gear you show with the pink background are from Century Jet and are a bit lightweight (weak) for the big birds from information I have recieved. The Sierra gear will be a lot more robust (stronger) and much more scale in appearence. Bill would know more, but once the prototypes are finished in 1/5th scale, the gear can be scaled up or down as needed.

Skinny Bob

My Feedback: (12)

argon622, will one of these do? If so PM your email and I'll attach them.

Stickbuilder

Bob,

I would vote for the first one. That is a great copy. I am going to reference that post, cause as sure as there are WACO Fans out there, I'm gonna need it.

Bill, AMA 4720
WACO Brotherhood #1

SuperCub Man

Thanks Bill - seems like a great idea - providing I've got it straight. Great description by the way!! I'm quite obviously no artisit or draftsman - but is this the general idea? Things would be tidied up somewhat, not looking like my drawing!