Problems and Errata

Let's help each other keep up with what difficulties we encounter during construction. If you have a problem come up, please email me details and I'll add it here.  Or, even better, ask your question on the Fly Baby mailing list.  There, you'll have access to a number of other builders.

Please note: These are not OFFICIAL notices. These are just problems noted by various builders. Since I haven't built a Fly Baby myself, I can't really judge whether there is indeed a problem or just a misinterpretation by the builder. Where I think a misunderstanding has occurred, I'll discuss it with the builder before adding it to this page. I may also add some editorial comment here and there.  My comments will be in italics.

One important thing to note:  Due to photocopier distortion, the "full size" templates in the plans are probably slightly off... significantly off, in the case of the wing-rib templates.  Builders have generated replacement drawings using CAD packages, and I've got PDFs of the drawings on the Templates page.

Note that the Rib templates are especially effected by this copier distortion!   Fortunately, that's one of the templates available.


 Landing Gear Fitting Problem

Steve Langford reports:

Horizontal Stabilizer Span

A Fly Baby Mailing list participant asks:
Pete writes in the notes that the 8 ft span of the stabilizer is slightly less than optimum. I'm planning to use an O-200 and I'm expecting empty weight to be a little heavier than optimum as well. Has anybody made the span 9 ft? Anybody aware of a single seat 'baby with a tail span over 8 ft? I'm finished with the rudder and I'm ready to build the stabilizer but I'd like to explore this before I do.
I talked to Pete about this one.  The comment in the plans about eight feet not being quite enough was written *before* the fuselage was lengthened six inches! The design change negated the wish for a bigger tail.

Aileron Construction

Drew Fidoe notes:
I have been looking through my FB builders manual, and under "Aileron Construction" page 4-27 the bottom of the first paragraph states that the construction methods (for the aileron spar) are detailed in section 3 for elevator and aileron spars, Figure 4-31.  I think that it's a typo.
Drew has an older set of plans (#285, in fact).  Later sets of plans has the "-31" XX'd out, with "-30" typed below.

Biplane Hole Spacing

A Fly Baby Mailing list participant writes:
Note: Check out the details of figure 10-7 (Detail A) and compare the hole spacing with that of fixture S-4 of page 4 at the end of the biplane plans. Also compare with fixture S-1 of page 12 at the end of the biplane plans. I am in the process of getting 1 1/4" spar hole spacing to mesh with 1 3/4" attachment hole spacing. Neat trick. Next trick is to get 1" thick N struts (plus brackets) to fit the 1 1/4" spar hole spacing and have room for the bolt heads. Hope to have this thing flying before I lose all my hair from scratching my head.
Drew Fidoe answers:
Hi, I'm not a 1B builder, but do have a couple of copies of the bipe' supplement. I looks like there may have been a plans revision somewhere along the way and that all of the info wasn't added to the drawing? There appears that these drawings where drafted in two phases.

Top wing: On drawing 12 at the end of the supplement it appears to me that the dimensions of the 4 vertical holes in hardwood blocks at T-2 has been changed, but not updated on page 10-18 detail "A". Too me, it appears that slightly larger hardwood blocks have to be fitted at T-2 to ensure the same bolt to edge distance as illustrated in detail "A" to fit the holes of S-1 on page 12. I would use the S-1 plate as a drill guide for the four vert holes through T-2 to ensure that everything lines up. If you have to use a hand drill, make a thicker "dummy" of S-1 out of aluminum or hardwood to ensure that your holes are true.

Bottom wing: same thing, I think that a slightly larger hardwood block is required at T-2, front side of spar to fit dimensions shown in page 4. The 1" spacing is the N strut thickness, not including the thickness of strut reinforcement S-5. I would make S-4 as per the drawings and again use the drill guide method to ensure that the T-2 block holes are true to the fittings. You can use double sided tape to help hold your drill guide in place on T-2 to help minimize plate movement when drilling, and place bolts (as temporary alignment dowels) in each hole after each is drilled prior to starting the next.

There are some hand written notes in the margin of one copy of my plans, on Page 10-17: At the end of para 3 there is "CHECK NOTE" (with an arrow to the 'note' a couple of paras down). Here 'Detail "B" is circled and in the margin is hand written "CHECK THE HOLES IN THE (UNINTELLIGIBLE) SECTION BEFORE DRILLING THESE HOLES...MAKE SURE THEY MATCH UP"

I gather that Pete lost his draftsman at some point while putting the biplane plans together, and had to finish them with his own sketches.  As far as I know, there isn't a plans revision for the biplane wings.  Pete occasionally did change pages on the monoplane version; you can tell those by the date across the bottom of the page.

Tailpost Support Channel

A Fly Baby mailing list participant asks:
As I'm constructing the fuselage first, I finally took a look at the necessary fittings more closely.  Right out of the box I have a question regarding the tailpost support.
Fig, 1-11 indicates .032 steel and step 18 on page 1-18 indicates the same.  Yet the Bill of Materials on page 1-2 indicates .063 steel and Fig. 1-2 indicates using .064 steel.  Am I missing something?  I know that most issues are usually solved by thorough review of the whole manual, but in this case I don't see an explanation for the conflicting steel thickness.  Can anyone lead me down the right path?  Thanks.
Steele answers:
If you don't already have an Aircraft Spruce catalog, get yourself one right away. It is most valuable as a reference for materials such as metal. During the period of construction you will need to order several different sizes of 4130 steel plate. Often times you can use steel strap which will save on the time spent cutting and it should also save money. I have found that the thicker the metal the more difficult to get a more perfect fit on bending. Perhaps the .032 will fit the inside of the rudder post/fuselage area better. Also some of the size metals called for by Pete are no longer available and the Spruce catalog will help you select the next size closest to that called for. Happy Building.
Jeff Gray answers:
I scratched my head over the size discrepancy too. An innate conservatism swayed me towards the heavier gauge material, which was a bitch to bend using the hammer and vice method - but doable. Since then, I've peered in the access hatch under the tail of every Fly Baby I've encountered and the vast majority use the .032. If you go with the .064 you'll end up with a hefty chunk of iron, however, depending on the engine you use, a little weight in the tail might to useful to get the weight and balance to work out. With an 0-200 for example, you might need it. Alternatively, I'm considering taking a drill to the thing and turning it into Swiss cheese to remove some heft.

Drew Fidoe answers:

I checked my tail post support, it's .035". It has survived 35 years, 1100 plus hours and a hanger squashing perfectly. Previous owners taught themselves aerobatics in the 'plane, too, so I think that the .035 thickness is perfectly adequate. I built a bunch of new steel fittings (hinges etc.) and heartily agree with Steele in using dimensionally rolled strap/strip instead of attempting to cut out these pieces from plate, which is a LOT more work to finish to size, and more wasteful, too (of course I went the option 2 route as I must do everything the hard way).
My initial cut on this was to recommend the 0.065.  However, Drew and Jeff have convinced me that 0.032" is adequate.  It certainly is a bear to bend it up from the thicker steel.

Rudder Bow Layout

A mailing list participant asks:
While waiting for materials for wing construction I decided to lay out the rudder bow. I did the two inch lay out on the bench as described in the plans on page 3-5 and shown on page 3-7, figure 3-4. I see that the rudder spar is 52 1/2". It looks as if the bow fits tip to tip on the spar. I confirmed the length of the spar with the rudder post in figure 1-10. However, the 2" lay out grid yields almost a 54" bow. Am I missing something? Is the lay out just a general idea or is the 54" accurate? I know that the shape of the bow is not "critical" but I don't want to make it too short or too long.
Joey Robbins responds:
You're not hallucinating Greg. I finished my rudder about a month ago and I found the same thing when I laid the grid out.
The 52 1/2 " measurement is the critical piece of info. The curve of the bow itself can vary as long as the overall area is kept essentially the same.
Luis Hernandez responds:
I also scratched my head when I built my rudder, but after finishing it, I am starting to wonder if some of these "discrepancies" shown in the plans, are there not by mistake but rather by design.

When I measured everything (as the builder quoted above mentions), I decided the bow should match the length of the rudder spar exactly, so I glued the laminations based on the 52½" spar measurements. Well, as you know wood shrinks and expands, and guess what... once you pop the finished bow from the workbench, it contracts an inch or two. So, After carefully trimming the ends (a couple of times), I epoxied the bottom end and allowed it to fully cure, then I gently stretched the bow and glued the top end.

In hindsight, I guess I could have trimmed the bow a bit beyond the ends and that would have helped, or I could have built it a tad bigger (just like Bowers shows in the plans), and that would have worked even better.

After building several Fly Baby components, I, for one, have come to truly respect and admire Mr. Bowers' ability to condense the "how to Build a Fly Baby" in just one book. I'm sure he could have written many volumes just to explain why he did certain things a certain way.

Drilling the Wing-Wire Anchors

A mailing list participant asks:
Well, I can attest to Bowers' statement in the plans about the wing block holes being one of the most challenging aspects of the project.  After several hours of test hole drilling, I still don't have a way to consistently drill straight holes thru those little blocks (I'm using maple). Can someone give me a clue here? What has worked for you guys?
Drew Fidoe responds:
I haven't drilled the FB wing blocks but have done similar jobs on my airplane and shop projects.  Have you tried making a drill guide jig?  I've used pre-drilled 3" thick hardwood blocks, scrap metal plate/angle, and modified C-clamps to keep drills straight and on center. The guide doesn't have to look good, it just has to be rigid.  The guide acts as an alignment bushing for the drill bit and the trick is to have it thick and rigid enough to resist misalignment of the hand held drill.  I've used clamps, bolts, double sided tape and glue to secure the drill guides, what ever is on hand and works.
Bob Babcock responds:
I too have never drilled the holes but can highly recomend using a good quality brad point drill in deep wood holes as it will not wander the way a standard bit will in wood.  Lee Valley makes nice ones, pricey, but you can order a single size.  I have used two squares at 90 degrees to each other as a site guide when drilling long holes.  I wouldn't consider it without a sturdy drill guide though.
Paul Ralph responds:
As regards drilling holes correctly, if you cant get them to a drill press then and you inadvertantly miss, as is usually the case, then you have a very good modern option.  It is called old world craftsmanship in a can, or "epoxy" to the more serious minded.

The procedure is the drill the misaligned hole oversize by at least 1/8", and soak the hole with an epoxy sealer.  IFC S1 is a good candidate.  Then wax the bolt with parafin wax or any "release" wax which is well dried.  Mix up a good stiff mixture of a viscous epoxy  ( IFC G2 is good) with milled glass fibre until a stiff paste and stuff it into the hole with the bolt in place.  Force more in untill you are sure there are no voids and let it set.  It is often a good idea once the epoxy has firmed up for 12 hours or so to gently torque the bolt to make sure it releases.

There are two major considerations. The first is to ensure the new hole does not violate the hole edge distance.  The second is not to use stainless steel bolts.  If you are at all worried about the bolt bearing loads etc bear in mind that the proportional bearing stress in maple is about 4000 psi and in a epoxy/milled glass paste is between 20,000pis and 30,000 psi.  Even at high temperatures (250 deg C)  the bearing stress still way exceeds that of wood.

Wood is a superb composite material that has much exceeds other composites when buckling and cost is factored in but it does not do bolted joints well.  However local fibreglass allows it to overcome this weakness so well that I'm surprised if that evolution didn't diffuse more silicon fromthe soil than it allready does (perhaps a few more million years eh! )  In the good old days they used to use phenolic bushings and/or compreg which is a resin soaked wood.

This is an interesting approach.  I don't have the technical smarts to judge the merits or problems associated with it, but it certainly sounds good.  Keep in mind Paul's warning about not violating the edge distance requirements.

The original poster responded at this point:

Drew, Bob, and Paul,

Thanks for the tips. Late last night, after much head scratching and trial and error, a friend and I hit on success with one of the longest blocks. Due to the late hour, we only got the one done but we think the combination will work for the other seven. Our solution incorporates many of your suggestions.

Here is how we did it - in laborious detail. Sorry for the length but maybe this will help someone else down the road.

First we marked hole locations, top and bottom of the block. We used a nail set to indent the wood slightly. We followed that with a regular titanium pointed bit slightly smaller than the 1/4" to just barely cup the wood surface. We are using a hand held drill motor here. Then we stepped up to the 1/4" size but only drilled about 1/8" into the wood. We then built a jig on the drill press table of heavy angle iron to keep the block square to the bit and the table. We changed to a 3 point brad tip 1/4" bit and drilled VERY slowly half way thru the block. We made sure to back the bit out frequently for hole clearance and bit cooling. Turned the block over and did the same from the other side. As you can imagine, we had a very slight step in the center of the block due to marking inaccuracy and bit wander. We used a 1/4" straight fluted metal reamer to clear the step inside the hole. Bushings went thru fine and holes line up for brackets. Epoxy should take up any voids inside.

Dale Still responded:
You figured it out before I could reply. This is the right way even if you do own a drill press. Now, before you go drilling any more holes, get a good set of spade bits, the kind with the teeth out the outer edge of the spade. the 1/4 and 3/8 sizes will not have them. These bits are the secret to drilling plywood. Drill score the perimeter of the hole on one side, then drill trough from the other. Twist drills inherently make triangular shaped holes, but when you must user them , I recommend TiN coated bullet point drills.

While we are at it, the secret to drilling thick metal is GO SLOW. Set the belts on your drill press for your lowest speed. Once the bit bites and starts a chip, keep up sufficient pressure to make a continous strand. It looks backwards, slow speed and high pressure, but it works.

Comments? Contact Ron Wanttaja .