Thoughts from the workbench of Radical RC. The online retailer of electronics and kits for radio control aircraft. Dave Thacker shares his thoughts and knowledge of electronics, batteries, kit design and overall enjoyment of the hobby.
A customer wanted to know Keith Shaws Modifications of our 1905 Wright Flyer. Keith is an experienced modeler. A member of the AMA Hall of Fame. His advice on any model is well worth reviewing. Here are Keith’s views as written myself and on of our builders:
………….I really didn’t do much of anything to make the Wright fly “better”. Most mods were for convenience and scale appearance.
1) Made the front “head” removable so that I can transport it in my minivan along with other airshow planes.
2) Made the fantasy long range tanks to house the four A123 cells. Voltage/current/power is virtually identical to the 3s Lipo you spec. I just prefer the safety of A123 cells.
3) Used a tan magic marker to draw fake ribs and spars on the bare foam before painting with the Almond High-heat Rustoleum.
4) Made a dummy engine, sprockets and chains. Found a toy fireman that was just about the right scale for Orville. Sewed a suit and made a high collar, tie and cuffs for the figure.
5) My flier seems to need more positive elevator trim than yours at the given CG. I move my CG back to about 7/8″ back of the leading edge to reduce the front surface loading. This could be due to a slightly different camber profile than yours. Hard to guess when using the heat gun, ribs and rubber band method.
6) I used #117 rubber bands from OfficeMax rather than linking two #33 together.
7) I guess there were a couple of improvements now that I think on it. I found the vertical rudder hinge wire far too flexible and was the cause of the slow rudder oscillation. I used 3/32 instead of the spec’ed .055.
8) The roll axis was a little vague, and I suspected that the wing warping pushrods were buckling under load. I sleeved the .055 wire with 1/8th O.D. aluminum tubing. Now the wing warping is *almost* as positive as ailerons. Of course there is still adverse yaw from their use, so I mix in about 10% aileron-rudder coupling.
Hope this helps him,
Note’s from Dave; I do remember Keith mentioning that he runs the CG a bit further back than I suggest in the plans. He may have forgotten to mention that in the above letter. I do advise however that you start with the CG where suggested and only after a couple of flights, start to adjust it rearward. Any such adjustment should be made in careful small increments. 1/4″ is a long way to move a CG. Try to move it 1/8″ per flight until you find the uncomfortable location then readjust slightly forward. This is the method I used to arrive at the instructed location. For me it feels tail heavy any further back. By tail heavy, I mean, the model begins to hunt about the pitch axis. Keith feels that location is a bit further back and perhaps he is correct. Someday I may start moving it back again on my own model. Just bear in mind, you’re not experimenting to start where I suggest in the instructions. I want you to have a successful test flight.
Flew the Wright at a e-fly this last weekend. Saturday was beautiful, cool and calm. One of my friends took these shots of the Wright, thought you might like to see them. Also Dave Grife took a couple of short videos. Sunday was much windier and quite gusty (about 10 mph, gust over 15 mph). The Wright handled it fine with the modifications to the wing warping pushrods and the rudder pivot shaft.
First two minutes is Wright””
Note: Keith has constructed a take off dolly. As he takes of the model turns directly into the wind and leaves the dolly. I have no close up shots of the dolly. It’s a simple square board with two wheels up front, tail wheel on stinger and two pegs that catch a front cross member. Soon as the model lifts, it clears the cross member and leaves the dolly behind. The rear wheel is a smaller tail wheel type mounted to caster freely.
If anybody had a photo from that event they could let me add to this article, please forward. Thanks Keith for a fun story!
I just got back from the big judged scale meet (Central Ohio Scale) in Westerville. They had a great turnout, something like 47 pilots in 6 judged classes. I entered my Yak UT-1 in Designer Scale and got a third place. The first and second place were last year’s NATS winner and the Runner-Up, so not too bad for my first scale meet in about 15 years…
They had a “Fun Scale” class for beginners and experts, minimal static judging, but regular flight judging. I entered the Wright in Fun Scale Expert just for fun. The concept of doing “precision maneuvers” with the Wright in quite a bit of turbulence gave everyone a good dose of Comic Relief. It was like herding a cat around the sky. Surprisingly, I didn’t place last, as I got great marks for Flight Realism and the multi-motor option.
Early Sunday morning it was dead calm and ***very*** foggy. I flew a flight low and slow to the enjoyment of the spectators and contestants while waiting for the ceiling to lift so that the contest flights could resume. I recharged and waited my turn for the first sunday round. When it came time to fly, it was still very calm, and I had high hopes for a really good flight score. However, when I took off the plane pulled REALLY hard to the right, and full left trim on aileron and rudder and half left stick on aileron and rudder were required to barely fly straight. I struggled mightily to do the required maneuvers, and garnished about the same scores as saturday due to the awkward appearance to the flight and turns. Oh well.
I looked it over after a scary, but safe landing. The high humidity and wet grass had made all the joints on the parallelograms lock up solid. Even with the stain on the wood and the candle wax I rubbed on all the mating surfaces. Once it fully dried out in the sun, everything worked great later in the afternoon. Controls were back to normal, but of course, the winds had come up and the flight scores stayed the same as saturday. Can’t win… 🙂
But it got a LOT of attention, and many favorable comments. At the end of the first flight on saturday, it got a large round of applause and cheering from everyone. I think more photos were taken of it than any other plane at the meet. Hope one of them ends up in the contest write-up for the mags.
One of my favorite events. This is a smaller event where I get some time to fly and participate myself. Dry camping is available on site. It’s in the back of a horse farm inside of a practice sulky track. An interesting setting to say the least. It’s a very well groomed grass strip. Yes, you can get a ducted fan in and out on it’s gear here. There are often many scratch built models here to enjoy. See you there.
More info from Keith Shaw who you’ll remember has done some extensive scale detailing to one of our kits. Keith is an AMA Hall of Fame member. He’s tuning and trimming his bird and offers the following.
Now have 8 more flights on the Wright. Two improvements have GREATLY helped the directional control.
1) I found that the aileron cross pushrod was buckling. Increased wire thickness to 1/16th, helped a little. Rolled masking tape around pushrod ends and middle to get it up to the ID of 1/8th aluminum tube. Coated the tape with 5 minute epoxy and slipped the tube on. Wing warping is now very solid and uniform over flight speed range.
2) Mine had the few hertz rudder oscillation like yours. Carefully flexed everything back there and found that the vertical wire was wobbling all over the place at the bottom. The rudder pushrod was very solid in comparison, so side loads on the fins cause large distortion of the bottom inch of wire. Drilled out the boom bearings and plywood fin cross braces to use a 3/32″ wire instead. Rudder control is nice and solid and the oscillation is gone. Might have been able to get away with 1/16″ wire, but went for the 3/23″. Besides, I needed to move the CG back. 🙂
Now flying with CG about 7/8″ behind leading edge, still need to do some small tweaks on the motor thrust line. The plane now has a very solid feeling, with only a slight pitch bobble when it hits some turbulence. Flew it twice yesterday at an airshow in Detroit in 10 mph breeze with some minor turbulence. No problems. Before the mods this would not have been wise.
BTW, the crowd at the airshow LOVED it. More photos taken and questions asked than any other plane there.
At the field. Note the “cross-country fuel tanks”. Each tank contains two A123 cells inline, housing made of 1/64 ply and card stock. The 4 cells and holders weigh about the same as a 4 amp-hr 3s LiPo pack, but produce a little higher voltage. I pull 32 amp at full throttle, but the two flights so have been a half throttle. 6-7 minutes consumes about 1 amp-hr out of the 2.2 amp-hr available.>
Keith, an astounding amount of detail. I love the fantasy tanks. You mention flying it. I’m going through the emails one at a time as I’m posting them in the schedule.
I have noticed that although this model should be very energy hungry, when cruising around at slow speeds, it seems almost magical how little energy is used. Think about all that weight, you have to be around 60 ounces, all those struts, two props, two motors and two no-load currents (something worth a whole blog post to explore), both those wings and your only using about 150mah a minute.
I’ve never seen a mah per minute chart based on weight or style or anything else for that mater. However it seems if there were such a guideline out there, something is wrong. This model in my mind should not fly as long as it does on so little energy and so little battery mass relative to machine weight.
A little quick math shows cruise current should be about 9 amps (150ma per minute x 60 minutes). However, when you deduct the no load current (not sure what it is for those motors) we’re talking maybe only 7 amps at cruise for the pair of motors. Figuring a at load depressed voltage of 3.3v x 7 amps _ only 23.1 watts. Further, it would imply that two 14 watt brushed IPS gearbox’s would be able to keep this machine aloft and still have an excess 4.9 watts for climb. It seems impossible, yet, I know it is true.
You’ll notice a detail here. Keith modified the kit so he could remove the front frame and canard assembly for easier transport. Also notice the rib detail on the foam. Keith told me he purchased a marker intended for furniture finish repair. The marker was just a slight shade darker than the paint recommended to paint the wings. He carefully traced onto the foam all the rib locations and a spar. The idea being that when the wing was painted the marks would show through the pain enhancing the illusion of fabric over ribs. Great Idea! If I build another one, I’ll certainly copy this great idea. Dave
Photos of pilot and dummy engine mounted, along with vertical radiator. Note how easy it is to work on the plane with the “head” removed.
The dummy radiator is 3/32 ply with 1/8th balsa on both sides to make it look like a strut with rear-mounted radiator. Cooling tubes are cheap 16 gauge insulated wire. Additional benefit is that it helps stabilize the center ribs by keeping them from tilting sideways. Note also the 0.1″ carbon rod going between the top three center ribs. It serves several purposes, as it helps stabilize the center rib, gives a convenient CG locator (located 1/2″ behind the leading edge), and serves as a hard point for hanging that is not dependent on rubber bands or foam. I’ll later include a photo of the hanger in my living room, where the Wright now lives.
The removable head took some brainstorming, as I needed to come up with a way to do it so that I could take at least another big plane in my minivan to air shows. Once the head is off, the plane sits front down and occupies only as much space as a normal large plane fuselage. It is still tight, but I can fit my big Bearcat or Stomo or Bugatti or Goon or UT-1 in with the Wright. I’m sure another round of photos will be needed to show everything that had to be modified, but perhaps a Mark II of this kit will include this feature. There are total of eight 4-40 allen cap head bolts that are removed, but are screwed into blind T-nuts instead of the nylon inset capture nuts. I didn’t want to fiddle with a nut driver and the chance of dropping the nuts in the grass. The bottom four connect the sled frame members with a kind of a knuckle joint with the blind nut on the inside. The top four allow the various support struts for the front canard to be disconnected, again with blind nuts on the inside of the inner most strut. The two center vertical struts are kept in place with a short length of aluminum tube to act as a kind of bushing. The mounting holes for those struts and ribs need to be slightly drilled out to accommodate the 1/4 long pieces of tube. I lightly tacked the tubes and struts together with a dot of Loctite Stick N’ Seal, a flexible water-based product similar to RTV silicone rubber. Even though this all may sound complicated, I can remove or reinstall the head in less than 5 minutes. It does have the added bonus of making the plane MUCH easier to work on in my very small shop. All of my big giant scale electric planes that everyone has seen over the years have been built in my tiny 9′ x 9′ shop.
This series of posts created from email correspondence between Keith and I. He’s really done a lot of neat things to this kit. Expect a new report every Thursday for at least 5 weeks. Keith is in the AMA Hall of Fame. He is one of the fathers of modern day electric flight, a superb scale builder and solid modeler in many ways. Read more on the AMA website: Autobiography of KEITH SHAW
You can meet Keith every year at the Mid-America Flies electric fly in where he and Ken Myers of the EFO club host the longest running electric power meet in the country if not the world. Both are AMA Hall Of Fame members. Lots of scale modelers attend this event. Your sure to see many very nice hand built models here. The event is usually held in June and is always announced in the Ampeer Newsletter.
On to the first installment of Keith’s 1905 Wright Flyer Project:
First up is the dummy engine and magneto. Engine is made from foamboard, card stock, bits of lite-ply, dowel, and the chain is a section from a cheap necklace. Magneto is carved from pink foam.
Pilot is from Toys R Us, a “True Heros Fire Rescue, Robert Portman”. Very close to 1/7th scale. Had to use heat gun and some carving to pose him onto the necessary prone pilot position. Figure comes with boots and a bright yellow suit with day-go emergency strips. Fortunately the strips were sewed on, so easily removed. The uniform required some tailoring to make it look more like a 1900’s suit. The collar, tie and cuffs are all thin painted card stock. Toughest thing was trying to dye the bright yellow cloth to look right. The fabric is polyester and not easy to color. Tried RIT, then some aniline dyes without luck. Finally took a black magic marker apart, diluted the liquid, ad soaked the fabric overnight. It came out a black-green, and looks acceptable. I still have to make a cap for Orville, looking for better photos of that type of “Duster” cap he always wore.