Build Log Discussion - ksatter26

[ksatter26]

F2 kit with electric start Polini 303, cowl, and Oratex ordered last November (hopefully due in May). North Texas (Dallas) area. 4th A/C project (including a MiniMAX 1103R). New home with 30' x 40' hangar/shop and 700' grass strip. Retired Industrial Engineering Prof. Kurt Satter, PhD

[mrpilotron]

Sounds like you have a nice setup. If you're anything like me, that shop will be WAY too small within 2 years.

[Badland-F5 Pilot]

Wow - this is great. I would like to ask and volunteer to provide any assistance. I live in Rowlett and am waiting on Chris to build my kit, an F5. Since all the F series are identical in construction I would greatly appreciate the opportunity to even just document the build for you and any other help I can provide. Hope to hear from you soon.

Todd
Badland-F5 Pilot

[LA F2 Flyer]

Kurt, I'm envious of the size of your workspace. I built my F2 in a (barely) two car garage. It's a squeeze for sure! I'm in Los Angeles.

[ksatter26]

I'll be picking up my naked F3 kit on 8 Sept. I managed to get a cheap Southwest one-way flight from Dallas to Minneapolis-St. Paul and decent rate for a 16' Package Truck 0ne-way from to Dallas. Slightly more expensive than the $975 crating fee, but it keeps me off of the roads pulling a 16' converted flat-bed round trip. it seems that no company in the Dallas area has a long-bed cargo van for rent to an individual. I certainly tried.

Will do pictures and document the experience.

[Badland-F5 Pilot]

That is so cool Kurt. I'm really happy you'll be getting your kit soon, and that you found a way to get it home! I'll get a build log set up here for you unless you plan to do that somewhere else. I know that Chris would apprecate you showing your build as well I would too. I don't know how many times I've read the build manual that I have in PDF format, just waiting for my build to get started. Also, if you need a hand at any time (sometimes four are better than two), just let me know. I'm happy to help. I live in Rowlett, so I don't think I'm too far from you. Now I'm in envy of you! See what you did

[Badland-F5 Pilot]

OK Kurt, forgive me for just noticing your PhD - so you just earned the callsign "Doc"!

Todd
Badland-F5 Pilot

[Badland-F5 Pilot]

Kurt, I like the white powder coat airframe. That should look good if you go with the half-naked look like Peer has gone with. His is black, and he's gone with yellow Oratex which really makes it all pop nicely.

I'm going to have to talk to Chris about the titanium. I know he offers the powder coat with it. However, the rust that forms on bare Tatanium is clear and becomes inpervious to water, basically retaining its high metal shine. I'll have to see if the welded areas are a problem. Those I might have to be painted at minimum for protection.

You chose that Polini 303, very nice engine. They had a little trouble with it and US gasoline I at first, but from what I've been reading that issue has all eleminated and nothing but strong reviews now. I do like the water cooling. That alone is a big draw. Thermal shock is almost eliminated with a water cooled engine. I love the Hirth F-23, but it is air cooled. I've rode two stroke dirt bikes a lot when I was a kid. I never had any problems with them - other than the usual from neglect. Of course on a bike that just left me stuck on a dirt road or fire trail, not coming down and hoping to find a place dead stick land. Plus there was no weight issue (for the most part) with a two stroke on the ground, so they were built a little tougher. At least I would think that would be true.

I've been looking at both 2 and 3 blade props by E-Prop. Their carbon fiber props have a good rep. Matching up the prop with the maximum power of the engine and rotation I guess is the trick. Too big a bite out of the air and the engine never gets up to full power, not enough bite and energey is just being wasted because the prop isn't pushing all it could.

I'm going to have to take a deeper dive into Stewart Systems. There are a lot of older pilots that swear on the Stewart Systems. So far I've not been swayed away from Oratex, but that could change. Any particular item you like about one or the other?

Thanks,
Todd

[ksatter26]

Check out the U-tube later posts from John Croke on building the Affordaplane. He covers the tail surfaces and wings using the Stewart System and exterior latex house paint. My original order indicated a preference for the Oratex but I have since been sold on the Stewart System. A limited selection of Oratex colors vs even Ho

me Depot paint department matching any color sample. I covered my MiniMAX 1103R using lightweight Dacron and Home Depot paints:

With the white power coat and blue chasing red color scheme I'm definitely leaning towards the bare-bones configuration.

Currently finishing up my PVC "rotisserie" in preparation for the fuselage. Should make the fuselage work somewhat easier. The PVC contraption is rather contrived using some wire bracing but I believe it will be usable. I'll post pictures once I get the fuselage installed.

[Badland-F5 Pilot]

I'll certainly check out Jon's videos. I have watched many of them but not all through from start to finish. I've got the same concern about the limited colors from Oratex, so the Stewart System may be the way to go. I've read that the Oratex is paintable, and if no primer is needed, then that may be a better way. Of course if the Stewart System doesn't need primer, that also works. I'm thinking of going white with red highlights and trim. I really like the yellow and black, but I also want something that stands out a bit. I like the darker colors too, which isn't too great for longevity in the sun. I have a lot of time to decide. Those pictures of the max are really nice. And yes, please post the PVC rotisserie. I think Peer mentioned it would have been nice to have something like that set up when he was doing his wrap and working on the plane before assembly. I'm noting all the ideas from you, Tracy, and Peer so I won't have to re-invent the wheel so to speak!

Thanks,
Todd

[Badland-F5 Pilot]

I think Chris posted he's up to #19 so far on the builds. I am looking forward to getting mine. Is the serial number just a number.

Those rims sound pretty tight, but that also sounds pretty solid once together. Bummer on the pinched tube, but as you said - Walmart to the rescue. I'm getting the larger tires but may need to contact you about that shop if they are as difficult to assemble. Your adventure to find someplace that would assemble them reminds me of when I needed my truck's heater core replaced. For many Chevy's the entire dash must be pulled to replace the heater core. Many shops I went to told me nope, we don't do that. So much fun finding service from the service industry.

You're making great progress. Once it cools down a bit more I'll be you'll be really moving fast.

And yes on those pictures of the rotisserie please!

I'm still looking at the Stewart Systems and Oratex. I like both but even though the Oratex isn't going to give a shine like I would rather have, the lighter weight compared to the Steward Systems and then paint may be the swaying point. Oratex does make a wax to help shine up their fabric. Still, having some gloss paint on the Stewart Systems fabric would be so nice. It may come down to getting the assembly all together minus the fabric, then doing a weight check. If I'm clearly light enough, then the Stewart Systems may win me over.

Nice job so far Kurt. I'm enjoying living vicariously through your build.

Todd

[Badland-F5 Pilot]

Kurt, that rear wheel is looking pretty good, and interesting. You say it's a solid rod spring design. So is it solid, or does it flex like a spring? Interested in knowing how it takes the shock of landing? It also looks like it holds that tail up pretty high, or is that just the angle of the camera picture?

It looks like you went for heel brakes, is that correct? Never mind I just looked at your log post, and you have heel brakes listed.

You are really going at it, making good progress.

Todd

[LA F2 Flyer]

I was wondering the same about the tail spring. I'd love to see more pics of it. Also, how high does it lift the tail? I believe mine lifts it maybe three or four inches.

[Badland-F5 Pilot]

I was looking at it and it appears it really pushes the tail feathers up pretty high. That might just be the angle of the picture, but yes, I'd also like to know how high it raises the rear up.

https://badland103forum.org/phpBB3/viewtopic.php?t=142

Todd

[Badland-F5 Pilot]

"Kurt, so I take it you're not using the cables to hold the stabilizer? Instead, you're using rods?"

I would be inclined to test them for strength. I only mention this because someone recently told me that using aluminum tube struts for the wings has less strength than using cables. I'm not sure if it's true, but definitely worth investigating.

Also, what will the weight difference between rods and cables end up being? My kit ended up at the furthest rear portion of the CG range when build exactly to plan, so something to consider. Of course I am also using the lightest engine, so there's that!

[Badland-F5 Pilot]

Those tires seem to be troublesome at best. At least the one shop was willing to refund your money.

Todd

[ksatter26]

The solid rod tail-spring is a new feature from Chris. Goes together much more easily than the flat spring. Probably is the norm for all new kits.

Finished up the 3/16" 6061T6 rod flying wires today. The long delay was waiting for the left hand thread die. I bought 2 on-line, @ $4.50 each. I could not get them to stick the 2 Oz dies in a padded mailing envelope for USPS. The SOBs charged me $15 for FedEx ground but took 9 days to process the order. Anyway, the dies showed up and were only 3/4" wide ... good steel and cut threads well ... better than my Harbor Freight set of right hand dies. Will post pictures tomorrow on the build log.

I mounted the firewall to the fuselage today and the two piece welded engine mount from Chris. I think I have a problem ... the Polini aluminum mounting ring only aligns with 4 of the 6 mounting positions. I fired off pictures to Chris this afternoon but haven't heard back as yet. I hope it is merely an alignment error on my part.

I have done a trial fit on most of the flight controls and had to bend the elevator push rod from the stick housing to the reverser arm. I also had to trim the nose bushing on the stick housing down considerably in order to have the stick centered for all the control arms attachments. More pictures tomorrow in the Build log.

[Badland-F5 Pilot]

I like the new rod tail-spring. Looks great.

OUCH! $15.00 for shipping when they could have done it for a heck of a lot less. Well at least you got what you needed, and yes, most everything is better than Harbor Freight. With care, much of their cheap stuff will last a reasonable time, but cutting tools of any type (blades mainly) are not so good. HF however is my favorite toy store.

Certainly hope the issue with the mounting plate is simple, or does the manual cover mounting with all six bolts? Maybe that is a somewhat universal bracket for different Polini engines? I'm not sure on that one though as I thought I read somewhere that all Polini engines use the same mounting bracket (done originally for PPG rigs making it easier for them to swap Polini engines)?

You may want to talk to Peer (LA F2 Flyer) on his routing of the aileron cables. While Chris was making a few runs to Peer's home in Southern Cal. he noticed that Peer didn't run the cables the same way as in the manual, and also noticed that the control was much smoother. I recall Peer mentioning that Chris liked the routing better and was going to look at incorporating Peer's routing method into the manual. With how busy Chris has been that may not have happened yet. It may be something you want to check with Peer on though, just a thought.

Looking forward to the pictures!

I was going to head out to the Alliance Expo air show today, takes some pictures/video and post them in the multimedia forum. I screwed that one up though. Last Wednesday I figured I had better get my ticket purchased. I went to the ticket site and all the tickets were sold out! Sort of shocked me – an air show where tickets sell out? Never heard or that before. I kind of understand it since Alliance field is a depot airfield for both civilian and military aircraft. I suppose they have a lot of military guests, so they limit the civilian attendance. Kind of bummed out about it. I wanted to get the F-22 Raptor demonstration team on video. Oh well – the miss on the purchase of the tickets though did prompt me to get over to the Wings Over Dallas show coming up next month. I have my ticket and will be going to that show.

[Badland-F5 Pilot]

I do like those rods over the use of cables. I wonder how well tubing would work?

Todd

[ksatter26]

Chris took one look at the pix of the Polini mount ring positioned on his beautifully welded, 2-piece mount and said that it appears Polini has changed tge configuration of the mount ring. He's going to check and either get me an older version or fabricate one for me.

With the mount stumbling block, I spent the afternoon working on a template for the floor-boards. I took a lot of measurements and diagrammed-out a pattern in VISIO (my only drafting tool). I have some Hobby Lobby poster-board and will attempt a real pattern tomorrow (Sunday).

I have 2 nice, stainless, marine turnbuckles that I may try in tge rudder cables. I have a good niccopress snagging tool, but have no idea of where to find the use of a cable-tension meter.

Will try to get more pix tomorrow.

[ksatter26]

Sure enough, Chris has heard from Polini and we have the wrong mounting plate. He has the replacement and is sending it out today. I'll return the one I have to him.

[Badland-F5 Pilot]

It's funny in a way. I found Polini support for simple questions pretty poor. I've heard and read of others having difficulty from the same as me, simple questions, to very serious complex issues to be pretty poor. Sad that such a fine engine builder has a not so favorable support service. Sending the wrong part is not something new from Polini either. Great engines, not so great in other areas. Glad Chris is taking care of the issue for you.

I recently contacted Hirth about their F23. They promptly sent me .pdf's of all the documents I asked for and cc'd the American distributor, who sent me even more documentation. I found answers to all my questions. Just waiting now for an airplane

Your build is looking great.

Todd

[ksatter26]

Hirth makes a good engine. I had the F33 in my MiniMAX 1103R. Ran really well with a 3-bkade Ivo prop.

[Badland-F5 Pilot]

I think the Hirth will be nice. Chris offers several good engines, and I've looked at many of them, even the rotary. The price is a big factor, but I also like HP and long TBO's. I found some other engines that I like the design and power of, but the TBO's are half of the Hirth's. I like the Polini's, but there's one big thing I really like about the F23 over even other Hirth engines, that flat 2, pancake, boxer, whatever you want to call it. I want my forward view to be as unobstructed as possible and the F23 offers that.

[LA F2 Flyer]

The view over my hood COULD be a little better with the Polini, especially since my tailwheel is a few inches higher than it would be without the tailwheel dolly. I haven't added a seat cushion yet, which I think will help quite a bit.

However, if you are at least 5'10" (which I am just a hair above), you should be able to see over the cowl with only the slightest crane of the neck. That being said, there is something about that opposing twin that appeals to me as well. The sound is a lot more pleasant, and it carries the Piper Cub look just a little further.

[Badland-F5 Pilot]

Oh how I wish back to the days when I was 5'11". I've shrunk over the years as age has caught up to me. I'm 5'9" if my back is out of wack and 5' 9 1/2" if not

I do like the Polini's soft or wet clutch (don't recall if that's what they call it). I'm sure it's smooth both on the ground and at idle. It looks to be a lot more compact than a gear or belt drive, and I'd lay odds they simply don't fail.

With both you and Kurt using Polini's it'll be interesting to hear how well they perform. I expect only exceptional since Chris has been using them for some time. Kind of crazy that we'll be flying planes that don't have much more HP than the Wright brothers had. Of course our HP to weight ratio is miles better, but still, pretty cool that it doesn't take much to get off the ground.

[LA F2 Flyer]

The wet clutch is a definite plus in my opinion. Since I'll be taking my Badland to a local lakebed which also hosts ATVs, dirt bikes, and families camping, the idea of a stationary prop at idle appeals to me greatly. I wouldn't want to be responsible for a dog or child running into the spinney bit at the front of my UL.

As for the height, I think with a cushion the visibility will be fine for most of us. And a cushion WILL be desired after you spend some time on that aluminum plank.

[ksatter26]

Still waiting on my replacement Polini mount ring so no progress on mounting the 303. The engine comes in a nice welded tubular steel box frame so it is really ruggedized for shipping.

Chris says the tailwheel angle should be near 58.8 degrees mine is 56.9. He says that should be fine. I can slightly bend the rudder/tailwheel arms forward to gain a bit more than the 5.5" I have fir spring length. What I did was get to a good hardware store and got a pair of shorter springs with long hook ends which seem to work well

Just came in from the shop after swagging the nicopress sleeves on the pedal ends if the rudder cables. I'm going to get a good measurement on where the rudder and brake pedal springs should anchor and will pop-rivet a bracket to the firewall to make the attachments.

I'm also getting all of the strut and flaperon mounting parts together for a to the local powder coating guy. He can handle the 8' strut lengths. He has a minimum charge of $100 so I want to get all the smaller bracket parts in as well.

Not looking forward to the cold weather. The shop/hangar is not heated except for my rather small propane contractor's heater.

[ksatter26]

The replacement mounting plate fixed the positioning of plate-to- engine mount holes BUT the shock mount holes were bored oversize. Chris has made the CAD fike fix and I expect a good one in a week or so.

I got all the lift and jury strut parts off to the local powder coater. I expect those back next week as well.

Found a substitute for the Locktite Hysol 9460 epoxy. The distributors say Locktite us having major production problems with the product. The E60HP epoxy works well on securing the trailing edge to the flaperon ribs. Both left and right done. I also spliced the additional 2' of trailing edge material to the std 10' lengths in preparation for installation on the wings.

Started plumbing the fuel lines by installing a T-fitting from the tank. One path is almost straight down to a quick-disconnet fitting at the lower cross-member for draining the tank. Naturally the other runs to the engine. Trying to decide where to place the in-line fuel filter (probably on the engine side of the firewall) and the primer squeeze-bulb ( probably along the port-side of the cockpit just forward of the flap handle). Hope to post pictures later.

Weather has been nice and warm, but forecast is for a cold front this weekend. I'm afraid my shop hours will be somewhat reduced.

[Badland-F5 Pilot]

Wow, sounds like Polini just wanted to mess everything up!

Is there any noticeable difference in the dry times or strength of the epoxy?

Smart on putting the filter on the engine side of the firewall. I like the idea of having as few connections inside the plane as possible. Reducing it to, what, 3 connections not including the one at the tank is far better than adding to more in for the filter. And glass filters are nice but don't take vibration well (if they come loose), and plastic – I don't care for them. I've seen many leak. There are some good ones, but just keeping the filter outside sounds like a better idea.

Yes, the rain came in didn't it! The backyard had just dried up enough from our last storm front that the dogs were no longer bringing mud into the house from the backyard. And what happens? Another storm that dumped a mass of water into my backyard! And worse, this storm brought in a big cold front. Looks like we're in the cold for at least a week, maybe a little longer.

The weather keeps the steps small Kurt, but it is progress for sure. Thanks for the update.

Todd

[ksatter26]

The bar positions the rudder Pedal in the neutral position as is the rudder also clamped in the neutral position for setting the control cable length. The L-angle is pop-riveted to the firewall and allows 5 locations for attaching the rudder and brake return springs.

The fuel tank drain quick disconnect is a nylon bulkhead fitting mounted on a bracket pop-riveted to the cross-member behind the seat. The lower portion of the valved fitting will have a length of 1/4" flexible fuel line attached and is inserted into the fitting only to drain the tank.

[LA F2 Flyer]

I like the drain quick-disconnect, as I haven't yet included one in my fuel delivery system. Does the tank sit back far enough not to interfere with the hose or bracket? And I'd love to see your fuel line routing when you are at that point.

[ksatter26]

I'll get better pix of the drain/disconnect ( nylon from US Plastics). I'm re-thinking the fuel line routing to the starboard side. The fuel level transducer wires are on that side.

[Badland-F5 Pilot]

The new motor mount sounds like it's a winner. Also waiting patiently for the pics of the powder coated parts. It's a bit chilly this morning, but hopefully you replacement forced air heater has arrived and is keeping you warm as you continue your build.

Todd

[LA F2 Flyer]

Your build is coming along beautifully! Like yourself, I also wanted turnbuckles for the rudder cables. I mounted mine next to the seat in the cockpit, in the interest of keeping my CG as far forward as possible, since I am using the lightest Polini in my UL.

I also love the mounting setup for your fuel primer bulb. Looking good all around!

[ksatter26]

As requested ...

Elevator Push Rod coated and installed ...

Lift strut and flaperon mount parts (done, but not pictured are the jury struts)...

New 80K BTU shop heater ... now I just need some gap seals on the hangar door-frame.

Will get a better pix of the entire fuel system when I complete the hose connections.

[Badland-F5 Pilot]

Looking really nice Kurt. I really like the way the powder coat came out. You must like it too. Just in time on that heater too. Seems we'll have a wet cold week coming up. I just put on some rubber/flexible seals on my garage door (one for each side), and it does make a big difference. I also took a look at your fuel routing and control connections. They are all really impressive. Do you have any concern over any added weight or is there any with using turnbuckles?

Todd

[ksatter26]

Some concerns. I believe I can make the battery removable since the pull starter is integral to the Polini. Will check the weight once I have the wings on.

I'm going to have to check with Chris. I have been over the manual and few pictures several times and am pretty much in the dark about the use if the piece of aluminum tubing "jig" for the spar ends alignmen; for "trimming" the fuselage mounting tubes and drilling out the mounting holes. Mine seem smaller rather than larger and in need of "trimming". More pictures are definitely needed.

[Badland-F5 Pilot]

Dropping the battery weight will certainly help, and even in a situation where a pull starter cord breaks or something else along those lines, there's always propping it. That's more difficult with a two-stroke, but can be done. As for the pictures, I guess that's part of what this forum is for – to give others knowledge over what we've found in our own builds. However, yes, it would be nice to have more pictures in the build manual. Even then, sometimes we just have to talk to someone as a picture may be worth 1000 words, but understanding (especially when it comes to our lives being on the line) might need verbal communication!

Todd

[LA F2 Flyer]

Can you clarify what you mean by "the piece of aluminum tubing "jig" for the spar ends alignment" and "trimming" the fuselage mounting tubes and drilling out the mounting holes"? I'm not sure I recall either of these processes in my build, but can possibly provide some insight with a little memory jog.

I don't recall a jig for the spar ends, with the exception of a piece of paper that helped define the location of the holes for the rivets.

[ksatter26]

I mean part # 60136 ... Wing Lug Pattern ... it is no more than a short length of tubing. Pictures and description in the build manual don't make much sense to me ... of course I'm not to that point in the wing construction/rigging yet ... just trying to understand.

The jury strut fixture is nothing more than a means to keep the two crimped ends aligned.

Once again the site is not allowing e to insert pictures. Will report the problem again. Hope to post later.

(attachment added by forum admin)

[ksatter26]

Only drilled one end of each for the AN3 bolt.

Trial mount if the engine to locate the positioning of components on the firewall: starter relay, fuel pump, fuel line/ filter, pass-through for throttle,, CHT, AND EGT cables.

[Badland-F5 Pilot]

Pretty nice getting that correct engine mount and getting it in place. Looks sharp.

Todd

[LA F2 Flyer]

Looks good. I love the powder coating.

I think I know what you are talking about now. I didn't have it on my parts list; it was added after my kit. (Mine was the first kit sold.) Chris actually brought the piece of tubing when he came to help me assemble my wings.

If it's the 2.5" diameter aluminum bit, it's a short section of wing spar. The idea is that you can use it to carefully file round the ends of the tubes that the inner wing spars slip over and the wing bolts fit through. Those little tubes (lugs, I suppose?) are slightly longer than the inner diameter of the wing spars.

As I recall, Chris had mentioned that without the little jig, you'd need to lift the entire wing each time for a trial fit.

Be sure to file a slide radius into each lug, in an effort to match the inner radius of each spar as much as possible. File a little, then test...repeat. You want it nice and snug but without gouging the inside of the spar when deploying the wings. A good snug fit = minimal play.

Hope this helps!

[ksatter26]

Most definitely helps ... thanks. Not there yet, but making progress.

Good friends head me complaining about our last cold snap and all chipped-in for a really nice Slaght128 Heater/Air-Conditioner. Along with my *)K BTU propane heater, it ought to heat the hangar/shop nicely. Looking forward to see what it will do next summer in the Texas heat.

Thanks again.

Kurt

[ksatter26]

I have the 55mm E-Prop mounting bolts. The WhirlWind prop on my Viking 110HP used Nord-Lock washers. Thinking of using them on the Polini with locktite and torqueing to 8N-meters (70 in-lbs).

Any thoughts out there?

[Badland-F5 Pilot]

Question about the prop Kurt. Do you know of any online or even in text documentation on figuring out what size and pitch is best for a said engine's RPM and horsepower capability? I'm asking because I'm trying to help Peer with a potential too large or too much pitch prop on his F2 and Polini 202. The engine has his 6100 RPM, but only a few times. I believe that Peer mentioned redline is 7200. We can't figure out if there's a carb/fuel issue or as he and I have been discussing lately, the prop has too much pitch for the Polini 202. I've looked around the Internet trying to find something that will work to determine if there's a prop size or pitch issue. Any ideas?

Thanks,
Todd

[LA F2 Flyer]

Hi there - actually, it's the Polini Thor 200 evo swinging the e-props fixed pitch. 59.1" diameter prop. I am told static timing should be around 7200rpm, but that may be for a paramotor, which has a 51" prop typically. Redline is closer to 8500 or so, I believe.

I seem to be averaging 5400rpm...but that's with 10% ethanol gas. (I'm not sure how much difference it makes, but it may affect max rpm etc.)

I've tried jetting in every direction, checked compression, tested the stator and coil, and checked for air leaks so far...all seems to be good. To be honest, I'm a bit stumped.

[Badland-F5 Pilot]

Thanks for correcting and adding the additional information. I wonder if you're right about the gas. Since alcohol burns slower than gasoline, maybe that's an issue? It would be nice if there's some online calculation - enter HP, prop pitch and size, and get something out of it that'll tell what the expected RPM might be. I know that's asking a lot, but anything at this point I think may help either in a positive or dismissive way. I haven't been able to find anything and at this point even my prop will be a guess, which isn't ideal. Got to love Goole -

A lower pitched propeller will create more power due to more engine RPMs, but the boat will move slower. A higher pitched prop allows the boat to move faster by travelling a farther distance with each rotation. When choosing a propeller, choose a pitch that will keep the engine RPM in its recommended operating range.

This we know, but how? Plus most everything that comes up is for boat propellers! LOL

I did find this website, but the math is beyond my current capabilities - https://aerotoolbox.com/thrust-cruise-speed/

I did find another site that talked about maximum diameter shouldn't be more than 25% of the wingspan because of torque. The calculation was easy enough - Wingspan in inches X 0.25 which is max prop size. Using Chris's reference to wing size, that came out to be a max prop of 6.54 feet or around 78 1/2 inches, way above the size of your current prop. The article didn't give anything for pitch, which sort of makes that only slightly useful information.

This stuff could drive a pilot crazy!

Todd

[LA F2 Flyer]

It can certainly drive a BUILDER crazy! haha