Herr 18" Taylorcraft

Herr Taylorcraft Kit Review

First Glance: Typical Herr packaging. Stout box, well packaged, plenty of propaganda to fuel the fire for more kit building. Not sure I like the prop that came with the kit. Tissue is nice color, but throw away quality. At first glance the plans are well done (I'll bash on them some shortly), though it shows a prop hook with no winder loop. The Herr Taylorcraft is really a simple scale airplane. I don't feel that it's any harder to build than say a Sig Tiger or one of the Peck cabin jobs. But I'll change my mind on that before I get done too.

Construction: Fuselage construction is of the common "build two sides, glue them to two formers, pinch the tail and fill in the rest" construction. One thing I pondered in depth was the amount of curvature expected of the longerons (both top and bottom) on the fuselage side frames. There is a lot of contour formed to expect them to remain flat when pulled from the board. I'm probably re-inventing some technique (and perhaps this is an unecessary step), but I stress relieved the side frames by wetting the wood slightly after pinning and gluing, making sure not to soak the glue joints. I then left the side frames on the board to dry overnight (I build one frame at a time. I don't have the guts to glue one right over the other, and I don't see how one could build accurately by stacking them with more wax paper. But that's me). The two sides remained perfectly flat and the fuselage built up with out my usual twist, so I'm happy. One step that may save time later is to mark the location of the side stringers on the side frames before building them up. The side stringers are added in one of the last fuselage steps. To have them previously marked would be nice. I managed to chase the locations down by scaling the plans, so it was only a very minor setback.

I had difficulty visualizing one item, and I contacted Tom Herr for the answer. My concern was regarding the forward ending point of the upper side stringer. It is concealed in the side view by the rear strut. One can (correctly) assume that it ends at the back edge of the side windows, but it requires a significant "tuck-in" to make the curve. It seemed odd to me, so I asked "the man". After e-mailing him, I managed to look at the picture of the finished airframe that is included on the instruction sheet (doh!), and you can easily see where the stringer ends. To make the tight curve, I merely glued the front end of the stringer to it's tucked in location with CA. From there it was a simple matter of laying the stringer down along the marks I made and gluing them with a more conventional glue (Duco in my case). The lower side stringer also has a tucked in spot up by the nose block which I glued in the same manner. No problem. The curved in area of the upper stringer does look a little bumpy, but as Mr. Herr said, a few passes with a sanding block and it looks fine. Looks very scale like when covered. I managed to get through the tough step (bending wire) without messing up. Adding the remainder of the stringers was no major chore. A few of the bottom ones needed wetting to lay down without risk of breakage. If someone really wanted to shave some weight off this plane, the side frames could be made from 1/20" stick. Since most of the nose area formers fit into laser cut notches, the obvious choice would just be to go with VERY light stick in those areas. For the real weight freak you'd probably just build from plans anyway, to hell with the laser kits.

The tail surfaces are pretty basic, consisting of a few small laser pieces and the balance is 1/16" stick. I passed up the opportunity to convert them to hinged surfaces. I probably would have ended up with a heavy hack job tail anyway. By the way, I'm under the impression that the tail surfaces have not been enlarged. Certainly not the rudder and fin anyway.

Wings were about as easy as I've built recently. Build a small center section and pull it from the plan. The wings frame up quickly. Beyond thinking through the process a couple of times I'm sure I didn't spend more than half an hour on each, minus wing tips anyway. For those I pre-glued the laser pieces together and then fit them into place. They get blocked up and glued to the leading and trailing edges. I precut the angle on the top wing spars, and tipped the outer portion of the tip surface up to meet. There is some shaping that needs to be done in the area where the wingtip glues to the leading and trailing edges. I simply let the glue get good and hard and hacked away with a sanding block.
The wing panels are then joined to the center section, blocking up the outer wing rib 1/2" on each side. I feel it was one of the easier wing joining jobs I've done yet (that came out straight, anyway). I chose not to add additional dihedral. I think lots of people do this because it feels right, but since they don't build one of each they have nothing to base reality on. My .02

As mentioned, I tossed the tissue and replaced it with some red Peck japanese stuff. I went with the glue stick method on this one. The lower cowling has some pretty significant compound curvature to it. I am not one of the crowd who pre-shrinks tissue and then puts it on in little strips. I say put it on baggy and water shrink the crap out of it. I used four pieces of tissue (one each for sides, top and bottom). It has a few small wrinkles, but hey, so do I. This entire plane is being built as a stepping stone to bigger and fancier scale planes. I want this one to fly well and look okay doing it.

I took my time joining all the big parts together. It was initially very straight, with the exception of some wash in twist to the left wing (probably a result of me sanding the trailing edge too thin). I have since chased the wash in away everytime I've sprayed it with something (water, dope, paint). It currently has just a touch of washout on both wings, no other twists.

Speaking of paint, I tried the suggestion found on the FFML about use of Florist Paint. I'm hooked. Though I've always wanted to find a paint that doesn't cause the tissue to sag with every coat, this may be as good as it gets. The stuff dries quickly, and two coats of it weigh .7 grams. I rather like the translucent look of straight doped surfaces on sport planes, but I find the see-through-to-the-balsa-skeleton look a little distracting on a scale plane. The two coats of paint on this one are just enough to hide the balsa grain. Good enough for me.

My one major bash of mr Herr's plans are the lack of control surface outlines. The ailerons are there, but there are no tail surface outlines, and no doors shown. This was a real pain in the ass at 11:00pm for a guy with pen in hand and no scale docs. I managed to improvise the tail outlines well enough, but I'm having to dig through my jpeg supply for a good shot with an open door. A similar complaint can be lodged against the location of the tail bracing wires. The two points on the stab, and the point on the rudder are easy enough (since they go through the little triangle gussets you install), but the bottom location under the stab is nothing but a guess. I used the thread that came with the kit for the tail bracing wires.

Struts were easy enough. I began by sanding rounded edges on a piece of stock and then cut them to length. Mine are not tissue covered (though my gear fairings are), I merely painted them before gluing them in place. The 1/16" stick that serves as the rear strut is way too big for scale jury struts. I pirated a piece of 1/32" from an old Peck kit and used it, also sanded and painted before install.

Windows are one area I learned something. Namely, that side windows are installed before covering (in contrast to the directions). The windshield pattern is slightly overisized as stated on the plans. A little cut and fit of the paper pattern yields a very scale appearing windshield.

The waterslide decals are nicely done. I managed to screw one of the long ones up (I got distracted watching the '96 FAC nats video and turned around to see it floating in a twisted mess), and Mr Herr was kind enough to send me a replacement.

The supplied prop hook is no where near long enough. It ends about half way into the prop, verified in the two plan views that show the nose block assembly. I took the opportunity to bend up a reverse Z/S-hook (my first), and add the winder loop. I scraped the prop, just enough to clean it up and make it a little more flexible.

So how did it turn out? The finished plane, without rubber or ballast (which it won't need much of), is 15.4 grams. I calculate the wing area at 47.125 sq", for a preliminary wing loading of .327 grams/sq". That doesn't suck for a kit that is bone stock, save for use of jap tissue and the smaller jury strut material. A person could leave off the paint and decals, use balsa wheels, sand the crap out of it, use thinner windshield material, thinner prop and used a simpler prop hook to shave weight off my total.

It was wet and foggy everywhere this morning, so I had no chance to fly it. It's been clearing up in the afternoon's and I'm anxious to see this thing fly. Currently it's set at 0-0 incidence, though I've left the aft edge of the stab loose. I figure I can easily get 3 degrees of positive stab incidence if needed. Thrust is set per drawing.

The Pilot Report

You learn something new every day, don't you? I managed to fit in a 20 minute window of opportunity to see if the little plane flies. Close, but no cigar. Two things kept it from flying well yesterday.
1) In a statement above I happily mentioned that it wouldn't need much nose weight. I made this leap of reasoning based on the fact that it seemed to be so close in balance without rubber. However, a simple step back reveals that the T-craft is one of those short nose, long tail moment planes (meaning that you have to add a LOT of weight in the nose to overcome a tail heavy condition). Add to this aerodynamic conflict a rubber motor that extends well into the tail, which makes the plane even more tail heavy.
2) The dreaded left wing wash-in snuck back in while I was adding struts. With the strut/jury strut combination the wing was very stiff (hey, maybe that's why they put them on real planes!). Why I didn't notice the rather significant twist is beyond me. Worse still is that I still attempted flight in this condition.
Make no mistake, the plane flew yesterday. Flights of 5-15 seconds (depending on the turns in the motor)were achieved with a Carl Malden sized chunk of clay on the snout, and a little dab on the left wing strut too. Flying over a mowed soccer field, in wind, it was amazing that I came home with the plane intact. It is one tough bird. I cut my losses when my brain kicked in. With the twist in the wing, and having no way to lock the prop for an accurate balance check I was really wasting my time and risking damage to my model.

Back at home I cut the struts loose at the outer points on the twisted wing. By re-gluing them one at a time and holding a desired amount of twist until the wing was dry I achieved a balanced pair of very slightly washed out wings. I then used our friend steam to put a healthy dose of very permanent wash out to both wings. So much for that problem (I hope).
Next, I put in about 1/3 turns on the motor and locked the prop with a pin. I HATE adding heavy things to an airplane, and was disturbed to find that it took two dimes sitting on top of the "cowl" to bring the plane level at the desired CG location. I used my home grown method of making a sandwich out of the two coins with some RTV silicone aquarium sealant. Then by lightly goobering up one side of the sandwich I was able to drop it inside the snout of the plane where it is now stuck to the lower cowling. Out of sight, but far from out of mind. The plane now weighs (all up and ready to toss) 22.6 grams. Ouch. It is, however, just barely inside the magic .5 grams/sq." wing loading for a "flyable" plane.

Update 10/16/98

Well folks, it flies. I was getting 30-40 seconds yesterday without pushing the rubber too hard. Unfortunately I did considerable damage getting it trimmed for flight. At first it was experiencing a rather distinct right circle that tightened up as it went, ending with a classic spin entry at low altitude. The plane impacted on the nose and main gear more than one time, pushing the gear fairings into the lower longerons. Also lost in the impact was a main strut and some jury strut material. The main gear wire is plenty strong. If you're building one of these, just leave off the gear fairings until it's trimmed out.
I didn't have any materials to fabricate a wing tab, so I attempted to compensate with a significant amount of left rudder. At about 10 degrees I achieved satisfactory, though a little twitchy, flight. Attempting to pick up a wing with rudder, compensating for some unseen (at the time) wing twist creates a sort of directional declage. It is achieving forward flight (still r/r)in a cross controlled condition, known to full scale pilots (especially ones of no-flap planes like the T-craft) as a forward slip.
The flights yesterday were very consistent after I set it up this way. It flew well until it slowed for landing. At this point the low airspeed reduced the effectiveness of the small vertical area and it would fall off into a spin entry a couple of feet off the ground.
I repaired all the damage last night and added a clear plastic tab to the right wing. Using the tab I should be able to compensate for the inherent roll, and reduce the rudder input.
I mentioned the unseen twist. You can't see it, until you start rubbing your fingers on the covering towards the trailing edge. Apparently when it tightened up, it pulled away from the wing ribs on one side. Having air blow over the underside of the wing probably pushes the covering against the ribs resulting in a roll.
For the record, it does fly at 0-0 incidence, balance point as shown on the plan, thrust as called out.

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