Dave's XL F-71

[scottiniowa]

Artic, that's the way to do it!  That's the way the Eagles are supposed to be built!  No need for computer modeling and laser jet cutting.

That is so true, if " are supposed" would be traded for "could be"  

Basing most of this on the simple approach that "time is money" for a lot of folks.   in my case, I can cut all the parts out as shown in about 10 minutes... so I could do it  one way, or I can do another way...All depends on what you have and how you use it.  AS in nearly all aircraft there is about 6 different ways to do something.

[wojtekseta]

Dave, I'm not an expert, but I remember from the studies that leaving the rectangles in the structure badly affects of its strength. In my opinion in place of element parallel to the leading edge over your head should be one or two diagonals (like Leonard do in his CE). Just check it with more than me experienced person for your safety. Maybe in this case all is OK.


Do not take it as a critic, your work looks just impressive.

[Tom H]

Hey Scott, I'm not putting down the capabilities of CAD/CAM.  Your clear and precise drawings have been a big help to many, I'm sure.

My comments derive from reading of some who seem to get stalled out trying to get a part made, when all they have to do is "get after it", and, before long, the job is done.

Knowing the Eagles for what they are, I'm still leaning toward the "should be" direction, but, as you say, there are many methods, and each should use what is available.

[ArcticDave]

Dave, I'm not an expert, but I remember from the studies that leaving the rectangles in the structure badly affects of its strength. In my opinion in place of element parallel to the leading edge over your head should be one or two diagonals (like Leonard do in his CE). Just check it with more than me experienced person for your safety. Maybe in this case all is OK.


Do not take it as a critic, your work looks just impressive.

Good eye! I ran out of 1/2" tubing and have to order a bit more. The plan was a diagonal in each of those rectangles.
Never worry about critiquing what I'm doing...that's why it's here. The hope is, someone will spot anything too out of line and say something. I have a pretty thick skin and have been known to make mistakes



Tom...I knew what you meant and I agree. Computers have a place, but so does just doing it! In my 30 year career as a diesel mechanic/ fabricator I have seen many new kids start off in our shop trying to over engineer a simple part. Hell...I was once one of those "kids".  It only took me an hour to fab those gear fittings the old school way.  If a person has access to the programs and cutting equipment, then by all means use it! I don't however, and I don't feel my bird will suffer because of it.

[ArcticDave]

Okay, did something a bit different for the tailwheel. Keep in mind, that when I do something in an oddball fashion...it's normally motivated by the desire to use whats available to me. Well....sometimes I'm just weird. 

So far it's lighter than the 1.5" leaf spring I have sitting here. 
It may not work...only testing will validate it, but so far it appears to be strong enough and the spring rate seems spot on. It will just kiss the bump stop with all my weight on the tail.  It's a Ford valve spring....Lol

[scottiniowa]

Okay, did something a bit different for the tailwheel. Keep in mind, that when I do something in an oddball fashion...it's normally motivated by the desire to use whats available to me. Well....sometimes I'm just weird.

So far it's lighter than the 1.5" leaf spring I have sitting here.
It may not work...only testing will validate it, but so far it appears to be strong enough and the spring rate seems spot on. It will just kiss the bump stop with all my weight on the tail.  It's a Ford valve spring....Lol

Dave, I am just playing devils advocate here.  Not saying this won't work.

But by your photos, when you get side load on the tail wheel (and we know that happens)  the vertical spring with rubber stop, can't do much for your side load, and I don't think you want to transfer this same load to the front cross pin. While I have not done the math on it, that might be a tuff call for the U bracket and front cross pin to NOT bend or wallow out.

second thing to consider- if you can hit the rubber stop with just your weight on occasion,  then you may want to consider what a 1G or even 2 G landing might imply for your tail loads.  YOU won't be able to count on the short amount trailing your Ford valve spring to flex much.

Now I know, money cost for each part of the plane rules a lot, but going how Sam B, did his or some of the Kolb  7075 spring stingers might be something to consider, both way would not put you into a situation like above...

Just food for thought.  

Oh yes, there is also how the back yard flyer did/does their's    NO spring at all.

[ArcticDave]

Scott...your thoughts mirror my own. If you look at one of the pics posted earlier there is a shot of the upside down tailpost. There is a slotted cap that was welded on the bottom. That slot engages a pin that runs through the center of the spring and is welded through the swingarm. That in theory should alleviate the side loads on the pivot pin during turning. Is it enough? Good question...
The spring rate is an experiment. Leonards weight & balance sheet  included with the plans showed ~50 lbs on the tailwheel loaded. I guesstimated a possible 200 lb load back there if I get sloppy with a landing. I'm 220 right now. I think it may be enough but I'll hook it to the quad and pull it around the yard and beat the snot out of it awhile. If it bottoms too easy or wants to bend off to the side,  I do have an 1 1/2" leaf spring I can make a new one. It just felt too stiff in flexing tests.

As always thanks for the input!

[ArcticDave]

Progress on the tailwheel today. Initial results seemed promising. Will do further testing once the landing gear is finished.

[PropMan]

Looking good Dave!

[ArcticDave]

Thank you Frank!

[ArcticDave]

I'm welding the gear fittings to the fuselage and would like some feedback from prior builders. If you look at the pics below... on the rear fittings, the upright(to the seat back) slants rearward causing a triangular shaped gap. I was planning on just cutting a small triangle of .090 to fill that gap.
Is that the proper way to do it? Or do you just leave the gap there?
Thanks!

[Dan_]

Ounces add up to make pounds...

Welding looks awesome.

[ArcticDave]

Ounces add up to make pounds...

Welding looks awesome.

Muchas gracias Dan. 

I didn't want to add something not needed if I can help it. That bracket has a death grip on the fuselage as it is. 

[scottiniowa]

I'm welding the gear fittings to the fuselage and would like some feedback from prior builders. If you look at the pics below... on the rear fittings, the upright(to the seat back) slants rearward causing a triangular shaped gap. I was planning on just cutting a small triangle of .090 to fill that gap.
Is that the proper way to do it? Or do you just leave the gap there?
Thanks!

I am still searching in your photos for this gap?  Are you meaning a gap in a cluster?  or a gap in a bracket after welding, or neither?

[ArcticDave]

This gap Scott. Between the fitting and the cluster.