Kent Ashton

16. BURRING THE AIRFOIL PROFILES - Align the end of the burr with the template follower (pic 4). Pic 1 shows the result with the burr. When both sides have been profiled, return to the band saw and cut away as much excess wood as you dare. The more you can remove, the better. You might get down to 1/8" to 3/16" of wood left to remove by hand. I nicked a piece out of the profile (pic 3) but it was no problem to fill later. I used a wide-tooth wood cutting blade in the bandsaw. Go slow. The blade drag still stopped my bandsaw several times. On my first prop, I took a picture of a hub and imported it into CAD, drew over the picture and scaled it as required and make a template for rough-shaping the hub (pic 5). I didn't do that for this prop and it was a mistake. It made the hub harder to blend into the blades and I didn't get the blend symmetric on both sides. Sigh.

15. USING THE PROP CARVING MACHINE - (pic 1) I glued my extra paper templates to 1/2" MDF, cut them out and floxed them to a 1/2" board to become a template in the carving machine. Obviously you will also need a 1/2" board under your prop blank. I was afraid I might rough out the profiles too thin so I put a thin sheet of formica under the template to raise it a tad. This would make my rough cuts about 1/16" thicker than the basic template and the entire prop would rough-out two formica-thicknesses thicker. Necessary? Maybe not. I left some extra wood on the end of the tip (pic 2) and left the tip at the full thickness of the blank for now to aid in clamping the blank. Note that your blade centerline make must remain on the end because you'll cut away the centerline mark down the blade. Before starting with the machine I removed some excess wood with the bandsaw, otherwise the router would not go deeply enough in the blank. This is tricky because you could cut into the finished profile. I marked up the blank with various lines and marks to show the general thickness of the blades at each station. Difficult to describe how to do that. Pic 3 - I found it was useful to use a drill bit initially and drill holes for the profile. The drill removed wood a little easier than my burr. The drill got hot! Pic 4 - shows the other template for the flat side and roughed-out drill holes.

14. MAKING AIRFOIL TEMPLATES - I printed out two copies of each airfoil. You need two because your bandsaw will remove a bit of the chord line if you just cut between the upper and lower. I glued them to some formica and cut them out on my bandsaw. Pic 1 shows the result. A couple of things to note: The tops and bottoms of the templates must be accurate for using a level to check the incidence at each station while carving. I needed to add marks for the end of the trailing edge. Station 10 is almost too thin to work. I was afraid to carve it that thin and it came out thicker than than drawn. A biggie: The leading edge of station 3 is higher than the laminated prop blank. Without some blending, you will have a sharp corner slightly behind the leading edge at Station 3. That station has to blend into a flat hub surface so it's not a big deal to smooth it after carving. Just to claify, the hub is 6 boards thick and there is an extra margin added above and below the hub added for Station 3, 4 and part of 5 & 6. The magenta lines show the extent of the hub. Pic 2 is the planform template used to rough-cut the blade profile. CAUTION: It is very easy (I have found) to get confused about blade orientation and wack off the wrong wood. I mark the hub "Forward face" and draw a pic of the blade orientation on the ends of the blank. I mark places "LE high here" and "TE low here" on the forward side and "LE low here" and "TE high here" on the aft face. (pics 3, 4)

13. DRAWING THE AIRFOILS - This was a bit tedious. I copied each scaled airfoil upper and lower ordinates calculated in Sheet 2 into a plain text file for each station. I called up a drawing of the hub and one-by-one imported the station ordinates into my hub drawing as a "spline". Magic! A to-scale airfoil appeared. To this I added a chord line from L.E. to T.E. and overlaid it on the hub with the midpoint of the chord centered on the hub. I used the CAD's "rotate it" function to rotate the airfoil and chord (grouped together) to the correct pitch angle. Frankly, I have forgotten the exact steps but once the spline function draws the airfoil it is pretty easy to manipulate. Now I had a drawing like the third pic in Step 7 above. At this point, I could have moved the airfoil to make a straight T.E. blade. As I said earlier, that would have made it easier to carve. Label these airfoils several place so when you start cutting out upper and lower profiles to make carving templates, you will know which one you're working with. Here is the text file for station 7.5 (75%). On the left are the chord stations and on the right, the upper and lower (minus) ordinates. 67x80Sta7.5.txt

12. INTERPOLATING BETWEEN STATIONS AND SCALING UP THE ORDINATES - Here is an explaination of the spreadsheet I used (pic 1). It has two sheets to it. The first sheet takes the Selig data for stations 10, 5, and 3 and interpolates between them for stations 9, 8, 7.5, 7, 6 and 4. Sheet 1 computes the various Y ordinates for each station for a chordlength of one (the X ordinate (one unit) is known from the Selig data). Now those X and Y ordinates must be scaled up to the actual chord lengths at the stations. The actual chord lengths are plugged in near the top of Sheet 1 but they don't get used until Sheet 2. Sheet 2 takes the X and Y ordinates from sheet 1 and scales them up to the actual chord lengths plugged in at the top of Sheet 1 (pic 2) Here is the actual spreadsheet. If that format isn't readable, let me know .PropbladeInterpolator

10. SIZING AND BLENDING AIRFOILS – Ah, here is some work. The three Wortman airfoils must blend together down the blade, and the chord length must change to fit the planform. With a 2D CAD program here's how I did that. 11. Each airfoil has “Selig data” in the description which defines the X, Y ordinates for a chordlength of One. For example, here is the Selig data for FX84W140 (pic) found here http://airfoiltools.com/airfoil/details?airfoil=fx84w140-il The data "wraps" around the airfoil from T.E. back to T.E. So I had the ordinates for three airfoil stations (10, 5, 3) and I needed to scale those up to the actual chord length at those stations as well as interpolate between those three for stations 9, 8, 7.5, 7, 6, and 4. I had the chord lengths for all the stations from Step 9 above. I plugged those into another spreadsheet.

8. The planform drawn at Step 6 gave me the length of the X-axis at each station and I had the angle of the chord at each station from Step 5. I made a little spreadsheet to trig out the chord length for each station. (Pic). Now I knew, for each station, the angle of the chord and the chord length, but what airfoil shape? 9. CHOSING AIRFOILS: Clark-Y and R.A.F. 6 are standard flat-bottomed airfoils commonly used for props. These airfoils are easy to carve and the flat side can be quoted for the pitch but eyeballing what current designers appear to use for airfoils, I chose three Wortman airfoils that looked similar to what I saw in use. At the tip I used an FX84W97, at station 5 (50%) I used an FX84W140, and at station 3 (30%) and FX84W218. These are of the same airfoil family but thicker towards the root. (http://airfoiltools.com/search/list?page=f&no=5)]. There is no science here. Just a WAG. These Wortman airfoils are not exactly flat-sided and there is an angular difference between the flat-side and the chord line but they are relatively easy to carve. There is a small reflex (curve) on the bottom surface at the trailing edge but that can be disregarded. Now I had the chord angle and chord length for each station but I had to blend (interpolate) the three airfoils for the intermediate stations.

5. DESIGNING THE BLADES: With the pitch angle and blade stations determined in step 2, I drew the 75% station pitch angle in CAD and additional lines converging on the same point on the Y-axis to determine the geometric twist (pitch) at the remaining stations. (pic 1) No fancy adjustments here for washout or “slowdown” near the hub—just a straight geometric twist. BTW, there is no use trying to draw any station below 30%--the inner part of the blade will have to blend into the hub. 6. PLANFORM: Then I drew out a planform of the blade shape and taper I wanted (pic 2) . This planform is the shape you would see looking straight at the prop from the center of rotation. The planform drawing is useful later for rough-carving the wood blank. I glued the planform drawing to some scrap Formica and made a template it to rough-out the blade shape on my bandsaw. The diagonal lines in the planform drawing are just to align the sheets of paper out of the printer. 7. I wanted to try tapered blades such that the blade tip would be aligned with the center of the hub as in pic 3. This turned out to be a harder prop to build than a prop where the trailing edge is straight and aligned with or in-plane with the face of the hub. Hertzler props are an example of these straight T.E. planforms. With a straight T.E., all the chord trailing edges are aligned on the builder's table and it is easier to locate the airfoils as you carve. This difference caused me a problem later because I was sloppy checking the tip alignment and built in a small tracking error between the two tips.

4. DRILLING THE CENTERHOLE AND BOLT HOLES: I made a 7” diameter steel template of the hub pattern (O-360 Lycoming: 6 holes, 1/2”Dia on a 2.375 radius) and an aluminum plug. First I checked the perpendicularity of my mill head and table and drilled the centerhole with a brad-point drill, then the 2.25” hole that fits on the prop flange. I put the aluminum plug in the 2.25” hole to located the steel template and the prop bolt radius. (In the pics below, I am using my aluminum crushplate and 3/8" bolts for the first prop but later I used the steel template). As I drilled the prop bolt holes, I inserted short 1/2” bolts to hold the template in position. Here I made a minor mistake by not drilling the prop bolts exactly in line with the blade centerline. That required a small azimuth correction later when using a Dynavibe.

Here's how I built a couple of props. The first one was good right out of the box--credit beginner's luck. The second one which I will discuss here took a lot of adjusting; you might find it interesting. At the outset, I will admit that it's easier to just buy a prop but what fun is that! There are probably easier ways to draw prop blades with a 3D CAD program but this is was my method. 1. The first thing is to decide what length and pitch to build. I kept a list of props I read about that a people were using with a given HP and speed range and put them on a spreadsheet. (pic 1) Comparing pitch is tricky because a prop builder might be quoting the pitch of the flat side or the pitch of the prop's chord line. There can be several degrees difference. I just assumed that every pitch was quoted at the chord line. 2. Pitch is quoted in inches at the 75% station. It is the geometric distance a prop with no slippage will advance forward in one rotation. However, a builder must know the chord pitch angle. My spreadsheet converted pitch-inches into a pitch angle. I chose 26.8° chord pitch angle for my 180 hp engine and a 67“ length. From some previous experimenting, I believe length is not too critical. Pitch and tip thinness make a big difference. 3. I used six nice maple boards, 3/4” thick, so the hub thickness would be 4.5”. I scraped them as recommended to open the pores and glued them together with Weldwood Plastic Resin glue, rolling glue on both surfaces and flipping the growth rings for each board, and clamped them tight for a couple of days. (pic 2) The Weldwood product was recommended because it has a more generous working time than Resorcinol.

Pretty good deal today at B-stormers: N575WA https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=575WA LONG EZ • $19,900 • GREAT BUY • Long Ez 0-235 797 hrs cruise 160 mph. Flys great, Basic VFR, King 135A GPS/Com, Ellison Fuel, Electronic Mag, Dual Controls very well built by NASA rocket scientist paint 6 interior 6 sold with fresh annual. Selling to pay for college Contact Steve Burkett 703-307-2428. • Contact Steven Burkett, Owner - located Virginia Beach, VA USA • Telephone: 703-307-2428 • Fax: 703-935-8311 • Posted June 9, 2019

Just to clean up this weight discussion, here is the final adjustment and the visual depiction of the weight vectors. I installed a 3 ounce rod (cut-off bolt) in the hub at a 3" radius and with four more engine runs, I added a .35 oz washer and a .75 oz, washer under prop bolts. This gave an IPS reading on the Dynavibe as follows: 1073 RPM: .07 IPS at 260 deg 2228 RPM: .04 IPS at 302 deg, in the "Excellent" range In theory I could eliminate the washers by adding a bit more weight in the bolt in the hub. I flew the prop and it felt good. I could get 2750 RPM at 8000 feet at peak power--an overspeed condition--but at the lean setting I usually use, it ran about 2650 rpm and did not throw a blade so it looks like it will be a good prop and I am calling this experiment a success. 🙂 I was surprised to see such a high RPM at peak power since the static seemed lower than I'm used to. It is interesting that no amount of static balancing around the centerhole would have put this prop in balance. It was only by trial and error with the Dynavibe that it could be worked down to a good vibration level. I am happy to have most of the weight in the hub which minimizes coupling imbalance For reference this is a 66" X 80" (26.87° chord angle) prop.

By experiment, I ended up with a bunch of weights shown in the pic above to balance my prop and pondered how to distill that down to one or two equivalent weights. I want to put my weights in or on the hub. Here's an idea for using a CAD program to do that: To illustrate, at the prop hub in the pic above I have two extra washers weighing 1.65 oz at 180 degree azimuth (from the Dynavibe reflector) on a 2.375" radius. Multiply 1.65 oz. X 2.375" to get 3.92 oz-inches at azimuth 180. Plot that vector on the CAD drawing. Do the same for all the weights, connecting all the vectors. You will see in my drawing below that the sum of all my weights came to 13.01" oz-in. at azimuth 207.71 deg. Any weight you substitute that gives a 13.01" oz-in at 207.71 deg result will be equivalent. Putting 4.33 oz. of weight in the hub on a 3" radius at 207.71 degrees is the same (4.337 X 3 = 13.01) . Or if you wanted to place weights under two prop bolts, draw the azimuth of the two prop bolts, one azimuth from the origin and the reciprocal of the other azimuth from the 13.01@207 point and measure their length where they cross. Prop bolts are on a 2.375" radius so divide the length (oz.-inches) of each vector by 2.375" to get the weight to place at each prop bolt. Neat huh! There is probably a way to do this with trig but the CAD program seemed like a good way. I statically rebalanced this prop and started over with a new bunch of weights, trying to keep them at the hub. (pic 2) After much fiddling today, adding and moving weights, I could get the Dynavibe reading down to .13 IPS which is in the Fair-to-Good range and a big improvement over the 2.00 IPS I had initially. My prop bolts were not long enough to accept a stack of washers so I made the angle seen at the bottom which is heavy by itself and added one more 1/4" bolt on it. This arrangement of weights is about equivalent to the pic above. You might ask "What is the radius of the angle + bolt?" I will hang it from a string in two directions and where the strings cross, that's the CG of the part, then measure from the part-CG to the center of the prop bolt hole to find the radius. BTW, I have Lightspeed ignition Plasma 1 trigger bolts in my flywheel that I never thought to balance. They total about .35 oz so today I put an equivalent stick-on weight inside the flywheel opposite the trigger bolts. I rebalanced my Performance Prop used one extra AN960-417 washer under a prop bolt and showed 04 IPS at 2490 RPM which is in the "Excellent" range. Finally, it appears my new prop is not going to give enough RPM. Static was only about 2300 but flying it will tell the tale. It should certainly be usable as a spare prop if it holds together.

Been going backward on my project prop. To review, the tips did not track in-plane--I had a 5/16" to 3/8" error at the tips. I shaved the face of the hub to correct the tracking error. My first try with the Dynavibe showed about 1.96 IPS vibration. Real bad. Then I had the idea discussed here https://www.canardzone.com/forums/topic/18661-kents-long-ez-project/?do=findComment&comment=63426 that shaving the hub might put the the crush-plate and mounting bolts a slight angle so I rebalanced the prop on my static and hanging balancer with the prop-bolts and crush plate installed on the prop. I ran the prop again with the Dynavibe and it was even worse: 2.33 to 1.86 IPS at idle. I was afraid to run it up it up with so much vibration. Adding various bolts to the flywheel and washers under the prop bolts began to bring it down so that I was able to see .32 IPS at idle and .11 IPS at 2051 RPM. (pic) The "Good" to "Fair" range is .07 to .15. It felt a lot smoother but all this weight was a puzzle. After all, it is the prop that is screwed up; adding weight at the flywheel, some 12 inches forward does not seem to be the ideal solution. One would think the weight change should be made at the prop. (BTW, I put my trusty Performance Prop on for a check and it showed .09 IPS ("good" is .07 IPS). I modified this prop some years ago and have only balanced it with the static and hanging balancer.) So I have abandoned my idea about crush-plate and prop bolts being off center (although they well could be) and rebalanced it through the center hole like a standard prop. The centerhole is not exactly on center anymore but rebalancing caused me to drill out a bit of the lead weight I had put in the hub from the last balance. That lead was on the heavy side, according to the Dynavibe, so drilling it out should help.) Next test, I will try to add weight at the prop bolts using large washers or maybe washers with extra welded weight on them. We know that a one-blade prop can be balanced and run satisfactorily so I believe if I get the weights right, this prop will be usable.

This EZ today. N55PM No cockpit pics. https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=55PM LONG-EZ RUTAN O-235-HC 125 HP • $38,000 • FOR SALE • Updatd Long-EZ - O-235-L2C 125 hp Hi Comp Lycon pistons, Ni plated cyls, LSE Ign, B&C Altr/strt/volt Regr, LSE III EI Mag on lower), K&N oil air filter, freshly rebuilt engine. GRT EFIS, LED Lts, Flown regularly and recently.New uphlstry with Shpskn inserts & Impact protection fm st cushns. Flown regularly fm AK to the Bahamas. Based KARR. Aerodynamic upgrades - Sam James Wheel pants, Lamb tires, and gear leg fairings. GU Canard (don't fear it -it's faster) Light Speed Silver Bullet Prop. on 6 inch extension. Tvl Pods. IFR&Nt cert aircraft Comps: 78/80 77/80 78/80 77/80. Cndl Insp 6/19 • Contact Dave Mey, Owner - located Geneva, IL USA • Telephone: 6306606258 • Posted June 1, 2019

Today's Barnstormers: RUTAN LONG EZ • $10,000 • AVAILABLE FOR SALE • AW cert, airframe log, O-235, gauges, trailer, plans, extra parts. Flown 400hrs. No prop. Project. • Contact Kevin Provost, Owner - located Manassas, VA USA • Telephone: 7602075101 • Posted June 1, 2019 No pics for the EZ. Also this Q2, N95LR QUICKIE Q2 • $18,000 • FOR SALE TO GOOD HOME • 1985 Quickie Q2, N95LR, 285 TT SN, Revmaster 2100D-75 HP-with new heavy-duty cylinder heads, Prince prop, Narco AT150 transpond with encoder, echoUAT ADS-B, IC A210 radio with intercom, MGL Xtreme EFIS with full engine monitoring, fuel flow and magnetometer. toe brakes and reflexer, new exhaust • Contact Hardey McDaniel, Owner - located Marion, IN USA • Telephone: 765-506-1167 • Posted June 1, 2019

Saw this Varieze scoop arrangement on a FB page. I can't repost the entire discussion but the OP said Yep, 170 KTAS is a good speed but it's hard to say what's the reason without a lot more info. It seems logical that more square inches of inlet is going to improve cooling but if it uses more air to do it, that would seem to increase cooling drag. A mass of air enters the plenum, slows down through the fins, then is returned to the freestream in the low pressure behind the engine. All that slowing and accelerating of the air mass uses energy. Perhaps the greater air mass here does not slow down so much. Perhaps the aircraft has more HP than usual, or was run at full rich down low. Heck, my airplane will go pretty fast if I run at full rich down low. That doesn't mean much. I am not knocking the cooling idea, just saying that I don't understand it.

If you do your own maintenance--which you are allowed to do--the main cost will be an annual condition inspection at $500-$1000. It seems like most insurance companies are requiring a CFI checkout and 10 hrs in type. There is some wiggle-room there. They might accept a checkout in a Cozy or with an experienced LEZ pilot. Liability insurance around $700 per year. My liability was $533 this year. Hull could run a couple thousand.

From the Cozybuilders Group: I post this to show that even some of the shabby-looking projects we see in the Sales thread are very repairable. Of course, they may turn out to be as much work as just building new but most can be fixed. This Vari (pics) got hit by an opposite-direction taxiing Pitts. Nice repair job here from the shop of Marc Zeitlin. My buddy in Europe has rebuilt a Cozy with a similarly-damaged nose. I have cutoff and replaced a winglet. People regularly replace instrument panels. Just get out the Sawzall and go to work! 🙂

You You got info from Aerocomposites. yes? Personally, I think I would build the rest of the nose and wait for a Cozy strut to become available. If the MKNG-6 is installed squarely in the NG boxes and operates in-plane with the aircraft centerline, it should be quick work to install the strut and wheel later. I believe the EZ strut is lighter and shaped a little differently at the top for the EZ NG-6. Jack Wilhelmson sells two versions of the NG-6--one EZ, one Cozy IV--which seems to confirm that. There is discussion in the Cozybuilder group archives about dimples in the lower casting to retain the casting, or drilling for a bolt. No opinion there. One thing for sure, the lower casting pivot should tilt slightly aft at the top when you're done on the wheel will be prone to shimmy.

The $9K EZ project above likely has sold; disappeared from B-stormers. Yeah, I thought that one was a great deal with_an_engine! The $10.5K ex-military EZ (Ebay) project above did not sell-way overpriced--try cutting the price in half. The $79,000 "Gorgeous Long-EZ" above has not sold. The $2.1K Quickie with the broken canard is still up. The $40K "red seats" EZ is still up. The $39.K silver EZ is still up The $49.K apple-green EZ is still up The $45K Ortel Ez is still up. The $25K Raleigh Craigslist EZ is still up. The $48.5K San Diego Craigslist SQ2000 is still up. BTW, if you are search Barnstormers for EZs. You will have to search for Longez, Long-ez, long ez, and long-eze. There is also a "Rutan" catagory but no "Puffer" catagory. 🙂 No Cozys seen.

This EZ today. Looks pretty good. Heck, an engine alone is $9K. Cowls and canard included but I did not copy all the pics. It would be a LOT less work than the ex-miitary project above. I see 38 people watching that one. LONG EZ • $9,000 • ACCEPTING OFFERS • Long easy for sale. lots of work completed. I acquired this project from my neighbor, but I have done none of the work. I am a little to big to fly this aircraft, but it would make someone a great project to finish and fly. It looks good and appears to be complete. the engine is a 1800hr. o-320 E2D. It turns over but did not start. There was no spark from the slick mags.This project is offered as is and the prop does not go with it. I don't have much more to offer except this project was always inside, has a full electrical system, lycoming engine and plenty of potential. Thanks • Contact Steve Behrends located Livingston, TX USA • Telephone: 8324437664 • Posted May 24, 2019

The Pennsylvania EZ-on-the-lawn project sold. This one. https://www.canardzone.com/forums/topic/21972-sales-ive-seen/?do=findComment&comment=63492

Interesting Ebay EZ in North Carolina: Patch on the nose says "Joint Project Unmanned Aerial Vehicle" and it has the look of a military experiment. I could not find any info on the N-number N999T_ but it looks to be all there. Item 323812386004 if you want to look it up. Lots there. I expect it could be flying again. Wow, we are seeing a bunch of these sad EZ projects lately but as long as they are sound, they can be resurrected. That's the nice thing about the Rutans: Everything can be rebuilt. Edit: Ya know, we have seen flying, attractive O-235 EZs on this list for around $25K. This project will take a $15K engine and still need a year of hard work to be made presentable. Maybe you call the owner, explain the reality to him and make an offer in the $3K-5K range https://registry.faa.gov/AircraftInquiry/NNum_Results.aspx?NNumbertxt=4SY

Seen on the Facebook Hombuilt Aircraft Exchange page. In California