# Zenith CH750 build...

Discussion in 'Member Project Logs' started by Taiser, Aug 26, 2012.

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1. Jun 3, 2015

### Taiser

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Now that the flaperons are all tuned up I had to instal the stops for them. I used some old touch up paint and dabbed them on the bolts where the stop goes. These are bolts that hold the carry through bearing for the tube.

Push the stops where you figure they should go and then you can drill the holes out.

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2. Jun 3, 2015

### Taiser

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Drilled the holes and elongated them a bit so you had some side to side adjustment play! The other notch is to clear a rivet...

My big mitts had fun in this spot...

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3. Jun 3, 2015

### Taiser

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Stops installed! Lubbed everything up and re-checked the flaperon travel to make sure nothing is messed up and it still looks good. I have to lockwire an elevator turnbuckle that I undid to get my hands in some spot and go over everything one more time, but that's it.

Parting shot, waiting for inspection!

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4. Jun 13, 2015

### Taiser

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Quick update...

PASSED!!!

<insert dancing jig guy here>

I'll have more info later. He was pretty thorough. Started at 8 AM and finished at around 1 PM. Now I just have to wait for the government paperwork to come. Some people get it in a few weeks others a few months! Lets hope I don't have to wait that long. LOL

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5. Jul 23, 2015

### Taiser

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Took over 5 weeks to get the paperwork back from the government, but yesterday it CAME and today at 7:15 pm "The Silver BB" took to the skies for the first time!!! I'll put a full PiRep on later, but short and sweet, she flew straight and true and hands off. Ball was dead center in hands off cruise!!! Temps all green, did the entire runs at 2600 RPM and the cylinder temps never went over 330F!!! And it was 37 degrees Celsius (99 Fahrenheit) tonight!!!! Put together a quick short video of the first take-off which was pretty lazy because I didn't know what to expect, but it was a non-event... the landing though... WOW that's a bit trickier!!!

At higher altitude we did a quick climb and it showed 800 ft per minute climb, again at 37 degrees Celsius!!! Me happy!!! Me VERY happy!!!! :ban:

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6. Jul 28, 2015

### Taiser

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Initial flight report...

Well, as the happy video I posted earlier showed, the "Silver BB" took to the air on 22 July 2015 at 7:15 PM for the first time. I wasn't comfortable flying this thing myself for the first flight since I had no time in anything like it. My buddy volunteered to take it up with me. He has no time in a 750 but is a 13,000 hour bush pilot and one of the best pilots I've ever seen. He owns a few Pipers and flew everything from Cessna's to Otters and Norsemen and I figured if he couldn't land this thing, nobody could! Only condition was that I go with him. He has limited experience with glass panels and I think he figured if a wing was going to fall off, then he would be taking me out with him! LOL! We put in just over an hour on the first flight with 4 take offs and landings. Here's what we thought of the initial flight...

THE SPECS

Just to go over what I have...

-Second edition CH750 STOL with a mostly standard build.

-115 hp -O-235 Lycoming engine with Zen Exhaust

-Warp Drive 3 bladed 72" prop.

-Mix of Dynon and MGL glass panel instruments

-Dual controls

-Zen upholstery kit

-VG's on the tail

-long range tanks (15 gallons)

-14.6 lbs of ballast in tail

-Empty weight is 905 lbs (yes she's heavy)

-Registered as an "amateur" built here in Canada with a 1440 lbs gross weight

FIRST FLIGHT

I put 12 gallons of fuel in each tank, since I heard that a full tank can cause some leakage around the caps at a high AoA, plus I was heavy enough as it is! With my buddy, myself and the fuel we were close to gross weight! To make it worse, it was +38 C out. It's been unusually hot out for the last week with no end in sight. My field is in Kakabeka Falls, Ontario and is at 1000' ASL. My Dynon showed the density altitude at about 3700 feet!!! Yeah it was hot, but if anything was going to show a flaw it would be in these temps! Only snag was my KX-155 Nav/Com died for some reason. I used a handheld as a backup, but our airport doesn't require a radio and on a Thursday night, it was empty anyways. It's going to the shop tomorrow and I hope they actually find something wrong with it, because taking all my wiring apart to find an issue will suck. We were just staying in the pattern doing circuits for the first flight. Did my third walk around and triple checks and we were good to go. I was terrified, my buddy wasn't. He'd looked it over, knew I use to be an AME and knows it was inspected so he had no qualms... me I kept worrying I forgot a bolt somewhere and the wing would fall off....

Engine fired up and purred with no issues, it warmed up quickly in the 38c weather... wind was negligible, maybe 5 km/h directly from the west. The runway in Kakabeka is 09/27 so that was perfect. We taxied down and I repeated what we talked about before in our pre-flight briefing, be prepared for the nose to come up FAST, keep the front wheel off the ground and let it fly off. Got to the front of 27 and did the run up, no issues... Time to go...

Smoothly and quickly my buddy put the throttle forward, first time in motion so I wasn't sure how the tach would read. I set the prop to about 10.5 degrees that gave me a 2250 static RPM. By my guesstimates that should give me around 2600 RPM in flight. Engine can go to 2800 but I saw no need to set it that high for the flying I was doing. I planned on resetting it to 2800 when I put it on floats. Turns out I was bang on. RPM maxed out at 2610. As expected the nose came up FAST, Wheel was off the ground in maybe 20-30 feet... playing with the stick (as seen on the video) my buddy got the nose to where it should be and it accelerated fast. Nose was kept lower than it should be, just to be safe. I'm guessing the take-off run was about 350-400 feet and it didn't take off like I thought it would, seemed to "mush" a bit, but once it hit 60 mph it jumped into the air and smoothly climbed out. We both guessed the high heat and humidity was really affecting performance, but the engine was running strong and the leisurely climb was still showing 400' per minute! Put the nose down a hair and the climb out was at 70 mph... just to be safe.

A few things really impressed me when I took control. The ball was dead center on hands off! I had no heavy wing, no left or right tendencies... in the smooth air it was flying straight and true! Pitch is INSANELY sensitive. It seems I have ZERO rigging adjustments to make!!! Very smooth in the turns and the rudder is unbelievably effective. I'm guessing I was pushing maybe 1/4" max, just light foot pressure really to keep the ball centered in the turns. I had no issues with the rudder being "stiff". It felt fine. The engine blew me away. Since it's basically been sitting for 3 years during the build, we left it at max RPM for the entire flight just to burn it in and re-seat everything. Oil pressure was 62 psi, oil temp around 155F and the max cylinder head temp I got was 330F!!! This is in 38 degree weather!!! Fuel burn seemed to be about 9 gallons an hour at full power and went down to 5.5 in cruise, but I haven't fully calibrated the fuel flow sensor yet, but that should be fairly accurate.

I was worried that my baffling would keep it too hot, or I hadn't calculated the openings on the cowl properly but if anything I'll have to baffle it more in the colder weather to warm it up! The trim stayed neutral for the most part, maybe adjusted it once or twice with a light tap. We did a few medium turns and after about 15 minutes came in for the first landing. Set up on final, at 60 mph but the sink rate seemed a bit high so we came in at 70 mph, again at near gross weight and 38c was the likely cause. I had informed my buddy of what to expect, and told him the best way to land it is with the power on and just do it like a glassy water landing...riding the power curve. He followed through but he flared just a hair high, saw the sink and corrected.

The 235 engine is heavy, but the balance I have is perfect. I added 14.6 lbs of lead to the tail to compensate and the CG is perfect on all my W&B calculations for all loading configurations. In retrospect I could have put a heavy battery back there, but I have a lithium on the firewall so I added the lead. Not fun, but I saved probably $25,000 installing this engine over a Rotax. It's probably a good 80 lbs heavier than the 912, but 25K is not peanuts, plus it sounds big and mean flying overhead, can't put a price on that! Landing turned out smooth and worked out well... his 13,000 hours came in handy! Only thing he thinks will be an issue is to make sure the rudder is neutral on touchdown, due to the steerable nose. After touchdown he looked at me and said "Holy ^&*%, you weren't kidding about the nose dropping!" LOL. We took it off the runway and parked it for a check-up. No leaks, no damage, no missing bolts and both wings were still on!!! Had a drink of water and went back up, mostly doing light air work, turns, a few steeper climbs that showed 800' per minute, not bad at near gross and so hot out! Did some other minor stuff. Max power speed seemed to be around 85 mph during light maneuvers. I didn't check it on straight and level but I doubt it got higher than 90 mph. I'm guessing it will cruise around 80-85 mph. I can live with that at about 5.5 gal/hr. Total flight time 1.3 hours. That was enough for the first flight. Three more landings were done, all but one were decent. One had a bounce. My confidence in the nose gear increased a lot after this flight... I kept thinking it was like a matchstick, just waiting to snap but it handled everything well. More flying was suppose to happen today, but we had another super hot day and thunderstorms rolled in. We're hoping for some cooler weather to see how much effect it has on the performance, but it's suppose to be hot all week! Now that my buddy is comfortable flying it, I'll have him up with me while I get a dozen or so circuits in. One thing I will say is that so far this is a KICK-ASS PLANE and I couldn't be more please with how it turned out!!! The fact that the rigging turned out perfect is a nice bonus. If you are building, keep at it. Trust me, it's worth it! That's about all I can think of for now, I'll add more info as the flights continue. Hoping to get back up tomorrow. I have some more video taken of the landings. I'll work on those to post them when I get a chance. Cheers, Smilin' Mark First take-off... First flight... 7. Jul 28, 2015 ### Taiser ### Taiser #### Well-Known Member Joined: Nov 28, 2010 Messages: 1,154 Likes Received: 973 Location: Ontario Canada First flights, take off from the cockpit. During the flight... visibility is INSANE!!!! Joe Fisher and steveair2 like this. 8. Jul 28, 2015 ### Taiser ### Taiser #### Well-Known Member Joined: Nov 28, 2010 Messages: 1,154 Likes Received: 973 Location: Ontario Canada Updated first flight video here... This one is edited from the start-up to the take-off with footage from interior Garmin Virb! This one is just some flying around getting familiar with the aircraft AND getting back into practice myself. This thing lands WAY different than a regular airplane and I haven't flown since last fall so I'm out of practice as well. Good to have a drinking buddy who flew bush planes for a living! Best instructor I've ever had! Also trying the different aviation overlays that the Garmin can put on the screen. I've got just over 5 hours on her now. Landings still tricky, but getting better. This thing is ROCK solid in cruise and super stable in flight. Visibility is out of this world. Leisurely climbs are about 400-450 FPM, pushed it a bit and got 800 FPM without trying... and still at over 35C here all week. I'm guessing once I push it and figure out the speeds it will get about 1000 to 1200 FPM in more normal temp air. Busy at work this week but hope to get back out this Thursday if the weather holds. Plan on re-pitching the prop this week-end and will go for the full 2800 RPM just for fun. Only problem I've had so far was a binding carb heat cable. Easily fixed that problem. Engine has been FLAWLESS. Hasn't missed a beat. Max cyl temps are still about 330F in 37C (about 100F) insane hot weather, Oil temps are 155 ish, insanely cool, thanks to the oil cooler and good baffling to it. I'll probably have to make some sort of shield for it in colder weather. Oil pressure perfect at 62 PSI. No oil consumption to speak of, over 5 hours and the oil level on the stick went down maybe 1/8 of an inch... One issue of caution I learned is to not fuel on a slight angle. I had one wing lower than the other by maybe 6" because I fueled on the side of the runway. Put 12 gallons on each side and went for lunch. Came back and found fuel coming out of the top lower wing but dripping from the flap area! Thought I had the dreaded crappy sender leak, but turned out the tanks cross fed to the lower one and it gushed out the top. Next time I'll fuel level or shut the fuel valve off. At least it proves the tanks should drain evenly in flight! Next flights I will determine what the stall speed is and see if I can get the landings slower. It's still a weird landing airplane and I have to get use to the unusual attitude on landing. Figuring out the stall speeds should make me comfortable coming in at high angles! Last edited by a moderator: Mar 20, 2019 9. Aug 2, 2015 ### Taiser ### Taiser #### Well-Known Member Joined: Nov 28, 2010 Messages: 1,154 Likes Received: 973 Location: Ontario Canada Still working on fine tuning things. Take-offs seemed a bit longer than I expected and climb performance was good, but I expected more considering the HP my engine was putting out. I had the Warp-Drive set to a "starting" pitch as recommended and tuned to the static RPM on a Lycoming, but that was mostly guess work since there aren't any official tables for a three bladed Warp-Drive. I decided to drop the prop pitch about 1 degree. You can tell in this short video of the first trial run and our reactions to the change... it was pretty impressive! It added about 150 RPM giving me 2650 in flight. Can only imagine what 2800 would do... The final tuning continues!!! Loving this thing more and more. Still no issues to speak of. Landings are still a hair tricky, just because of the decent attitude, but getting easier... take offs are now AMAZING and will most likely get a lot better with practice! It doesn't take off or land like what I'm use to, that's for sure! Warning... bad language, mostly because it surprised the hell out of us... Last edited by a moderator: Mar 20, 2019 CDNRV7 and steveair2 like this. 10. Aug 8, 2015 ### Taiser ### Taiser #### Well-Known Member Joined: Nov 28, 2010 Messages: 1,154 Likes Received: 973 Location: Ontario Canada Finally got my 10 hours in, which allowed me to solo and be insured! Finally got the hang of landing this thing, it sure is different but flies great, although a bit slow. I'm cruising at 80-85 mph at 2300 RPM. Here's a short video of my first solo on the plane. I hit 10 hours and changed the oil and filter, only because it's been sitting for a few years, so I ran it pretty hard to reseat everything in the engine but it has been running really well. I cut open the filter and there is nothing in there (no metal) worth noting. I took some photos and will post them later. Only snags so far was a binding carb heat cable and my left mag stopped grounding. Thought it was the switch, but turned out the P-Lead was a bit crummy. I cleaned it out and it works fine. Hoping the weather is nice this weekend. Want to pile on some serious hours quick!!! Last edited by a moderator: Mar 20, 2019 11. Aug 17, 2015 ### Taiser ### Taiser #### Well-Known Member Joined: Nov 28, 2010 Messages: 1,154 Likes Received: 973 Location: Ontario Canada I'm at 21 hours now! Only 4 more to go (trouble free) and I can start flying off to where I want. Took it out in some decent head wind yesterday and it handled them well. Landing are going well and much improved. Going to try coming in with some major flaps on and see how it acts that way. So far no major issues. Mag problem came back, added a small shim to the ground and it seems to have done the trick. If it happens again I'll pull the mag cover off and add some tension to the ground spring. Pretty common problem. Still no oil consumption to speak of. Sweet spot is right at 5 quarts. It's been sitting there for about 3 hours and has gone down maybe 1/16th of an inch. Lots of power and flies great. Hoping to do a climb test this week (need one for the final paperwork) but I'm getting about 800 feet per minute by myself without effort, should be close to that at gross with a decent angle. Engine temps are all perfect. Still get 330F max cylinder, around 60 psi on oil and oil temp is steady at 160F or so. Bit low but with the colder weather coming I'll block off the oil cooler a bit and see what that does. Probably install a damper with a control in the cockpit over the oil cooler so it can be adjusted as needed. She's not fast, about 80 mph cruise but flies great! Still loving the view on the 750 STOL! Don't get much better than this!!! 12. Aug 23, 2015 ### Taiser ### Taiser #### Well-Known Member Joined: Nov 28, 2010 Messages: 1,154 Likes Received: 973 Location: Ontario Canada Update! Got my 25 hours in... paperwork is back with Transport Canada for my final CofA. That will lift my flight restrictions and allow me to carry passengers and fly anywhere. Hope to get that early next week. Wife is anxious to go up, but I go out of town at the end of next week for my annual fishing trip so I'll be gone for a week... Fishing and buddies = but no flying = LOL One of the requirements for the final CofA was a "climb" test. Not sure about other countries, here there is a chart that is referred to that you plug in pressure altitude and current temperature and it calculates how much altitude you have to get to pass the test. In my case it was about 1100 feet in 3 minutes. BWAHAHAHAHHAHAHAAA Sorry, just seems like a pretty sad number. The plane has to be at gross weight. I got this with full fuel, couple of sandbags in the baggage area and weight plates. Was pretty easy to get 1440 lbs. Did the test, even if the wind at altitude was a bit higher than expected. I actually left the flaps on a bit longer than I should have, just because writing things down distracted me. Could have redone the test, but 3000' feet above my airport turns into controlled airspace, I hit that easily and averaged about 700 FPM. Good enough for the paperwork. I think with some playing around with angles and prop pitch I should be able to hit 8-900 FPM easily at gross... Don't really need that though. Worth looking into when I put it on floats maybe. Recorded the climb test if anyone is interested. It's the video below! Last edited by a moderator: Mar 20, 2019 13. Sep 18, 2015 ### Taiser ### Taiser #### Well-Known Member Joined: Nov 28, 2010 Messages: 1,154 Likes Received: 973 Location: Ontario Canada Well, little bit of dancing with Transport Canada... when I dropped off my paperwork, I had over 25 hours on the hobbs, which is what I thought they wanted, but turns out they wanted 25 actual flight (in the air) hours! Luckily, I had kept flying and all that was needed was an updated copy of my journey log. Had to confirm a few things in the log as well and pay a$35 fee... there is always a fee, and that was is! Transport dude (regional inspector for this area) was actually pretty cool. He took my updated paperwork and filled out my new CofA on the spot and I was good to go! Only restrictions now are "VFR Day flights only" and "No aerobatics". I can get the plane certified for night flying, but that's for a later date, if ever... Aerobatics... don't think so!

First passenger!

First one up was the Missus! She was pretty nervous, although she's been up with me before, but it's been a few years. Once we got up though, she loved it, but she's not a great flyer, don't think she will make a regular habit of coming up in this build, too much of a view and the fact that she can see straight down makes her uneasy! LOL

Virb action shot, cruising at 1000' AGL at a whopping 92 mph!!! That's actually pretty good, usually cruises at 78-80 mph... fast the 750 is not! Can't beat the view though!

Winter is now coming, but the weather has been spectacular. Think I can get another month of flying, that's about it. Maybe a bit more if I decide to start using some pre-heat, but flying in the cold is always a pain, not to mention hard on everything.

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14. Oct 6, 2015

### Taiser

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Changed the oil last week, just went to a lighter weight multi-oil (20w50) for the colder fall days. The bungee seemed fine on the right side, where I inspect it through the oil stick hatch. When I popped the cowl off, I noticed this happening to my Bungee! :mad2:

I never trusted this thing, so luckily I have a spare one I can install next week-end but this seems to be a common issue after posting this on the Zen site. They don't like heat and they don't like oil, both of which are plenty present in the current spot. I'll install the spare for now and get a steel viking "bungee" in the spring. I'm not going through this every 30 hours!!! :mad2: :mad2:

Everything else is beautiful though! The bungee did give lots of warning, the ride got softer and more "springy" on the ground and I could feel something wasn't right so it doesn't just snap, although that's been known to happen, it's rare.

I also have the custom made bungee install tool, but I'm not sure if it will work because I have a throttle bracket that I think it will interfere with the install. I'll post how the changeover goes! The steel bungee will add about 3 lbs to the nose... cry!

15. Dec 22, 2015

### Taiser

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Thought I would do a quick update! I managed to keep flying up until about a week ago!!! That was pretty sweet, but then it rained and it froze, then it snowed. What a mess!! Luckily I borrowed a buddies hangar until next year when I will build my own. I did manage to change out the bungee. As suspected, when I changed my oil and it dripped on the bungee it basically ate through it less than a few weeks. The oil coated side was easily sliced in half, the other, clean side, I couldn't even scratch it with my Olfa knife! Anyways, it's obvious that the bungee in this area is bad idea with the Lycosaur. I put in the new bungee for now (not fun) and will get a Viking Steel Bungee next year...

The old bungee in place, starting to disintegrate, but it held. Lots of warning, the steering got super easy and you could "feel" something was wrong...

Better shot of the oil damage...

16. Dec 22, 2015

### Taiser

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Bungee tool won't fit on my setup, too much junk in the way, including the Mags, and the throttle linkage...

Here's the tool... waste of money in my case, but I'll see if I can mod it somehow...

17. Dec 22, 2015

### Taiser

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Had to take the nose gear off anyways to get the bungee in behind it so I took it right out for inspection. The nose gear always made me nervous. No issues though, even after some pretty "sporting" landings, trying to master the STOL. It held up well...

Just some paint issues where the bungee rubbed on it, I can live with that!

18. Dec 22, 2015

### Taiser

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Inspected the nose gear channel too, nothing wrong with it. I thought for sure there would be something amiss in there with all the crap landings I did, but it's holding up fine. Seems I was worried for nothing.

New bungee going in... this was NOT fun! :mad2:

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19. Dec 22, 2015

### Taiser

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I used the "ratchet" method to put it on, only choice I had, but because it's so tight, it had to go at a weird angle (sorry no photo of the ratchet, just a large 1/2 drive one) and it took two of us to force it up. It basically chewed up the retaining tube!!! That tube is 4130 steel, so I can only imagine how much I was torquing on the thing to do this! Luckily it won't affect anything...

The bungee clears the damage. When I put in the steel bungee, I'll dress this area up. Zen, on a new video, recommends you change this thing once a year during annual now!!! Not a chance this is happening on my setup. The steel bungee will be cheap in comparison, not only for the \$50 bungee, but for my patience as well.

I kept flying until last week. I got about 48 hours on the hobbs now, not bad for a late summer start, weather is still unusually nice up here, but there is too much snow to fly now.

20. Dec 22, 2015

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