Kitfox 7 Apex Build Episode 34 Carbon Fiber update and Throttle Linkage.

[@ik04]

The cable binding as it comes out of the sheath will eventually fail. You need to use a curved cable guide, like the one on the engine. That aluminum arm should have support on both sides of the bolt to avoid wear and binding. An aircraft grade bushing on the pivot would help, too.

[@FatParamotorGuy]

I know this video is quite old now, and you're probably using/flying this build but I did want to mention the airbox. The purpose of the airbox is not to channel one inlet airstream into the four intakes. It's purpose is to ensure equal air pressure on each intake regardless of flow rate through the filter. Just doing a random box will result in differing air pressures and less smooth running engine. Airboxes are tuned by the ridges inside them. I am enjoying the build series though and have been working through each one. I do thank you for taking the time to do them.

[@davidrobins4025]

Attention to the details produces a beautiful finished product. I really appreciate your explanations of what you are doing on this journey.

[@mwiencek9809]

Hello. It may have been covered, but a a few suggestions. First, I'd consider a small drain hole in the airbox. This can be placed at the low point of the airbox in level flight.. to drain any ingested water from flying through rain. Second.. I would definitely mount the throttle return spring to move the throttle to full power if it ever broke. Lastly, the support for the airbox should be routed back to the engine case somehow.. not the mount/airframe.

[@rogerolander458]

Hi Brian, That "reverser" is really a "Bell Crank" which are wonderful devises. Not only can they change direction and length of the movement as you indicated but they also can be designed to reduce wear on cables and/or push/pull cables. You might consider a redesign to that straight bell crank so that it has the appropriate angle between it's arms. As it is now set up you will experience un-necessary wear and friction on both of your cables. The design might benefit if each arm is perpendicular to it's cable at the midpoint of it's range of motion.

[@chrispy104k]

Yes I agree with this point of view. Love the build process Brian, but this looks to be a potential source of failure in time. The bell crank suggestion from others is certainly worth investigating. Could you do something like this by introducing pivots where the cables are attached to the divider bar? That would ensure that the pull or push directions remained in line. www.dropbox.com/s/cg8decgunufeudi/ThrottlePivots.png?dl=0

[@rogerolander458]

@@chrispy104k The pivot on the left of your drawing is correct but I'm not sure about the one on the right because it loads the push/pull wire from the side so the wire will still try to flex at both full power and idle. I think the barrel type of swivel terminal is better because it will keep the loads centered on the wire.

[@chrispy104k]

@@rogerolander458 Yep, fair comment. It was a rough mock-up as a spur of the moment thought.

[@briand3837]

I really enjoy watching you problem solve and generate novel fixes that are of high quality.

[@rixtrix11]

Nice work so far on the cowling. On the throttle reverser, it seems the mount for the secondary cable puts a lot of strain on the secondary cable, pulling it to the side as it actuates. Could you incorporate a pivot where the cable attachment fastens to the reverser lever to allow a straighter pull on the secondary cable throughout the range of travel, so the cable and housing end wear is reduced or eliminated?

[@maleficentcop2752]

Nothing wrong with the content, looks like you got quite a bit done... Anyway good job... Hope you have a great Thanksgiving...👍👍👍

[@alistaircox3363]

Hi Brian Hi from Australia buddy. With the airbox you need to attach that brace to the engine as it needs to move with the engine,if you fix it to the mount will crack due mount solid to AF. Also radiator paint it black and make little fairing either side would help it disappear as it is silver it stands out!! Just some idea 💡 Cheers Alistair

[@BowenAero]

Great ideas, you are totally right about the air box support. Thanks

[@rogerolander458]

One additional thought: The push/pull cable really should be terminated in a "wire pivot" or some other swivel terminal. As you have the throttle linkage set up with those two fixed position cable clamps, the movement of the push/pull wire will cause it to fatigue, crack and fail eventually.

[@jassonhoskins367]

keep up the great work! enjoy your family for the holiday! as for content, i think you do a great job! you deserve a break too! looking forward to seeing more when it arrives!

[@edjcs]

Hi Brian - the way the cable on the engine side of your bell crank is mounted concerns me a bit. It looks like the cable has a barrel end to it which slots into some kind of adjustable connector. When the throttle is wide open, the cable looks like it's putting a lot of angular tension on this adjuster which will probably cause fatigue in the threaded part of it (I think these connectors are generally designed with collinear tension in mind). I wonder if it'd be possible to modify the design to reduce the cable angle and somehow allow the adjuster to pivot?

[@HookedOnUtah]

Bryan, the KF is coming along sweet. In the end, all the hard work and though you've put into this project will pay off big time. Great work!

[@danielbasovitch5087]

You Could opt for a grooved disc with the same pivot point? A radius will work much smoother than a straight aluminum tab. A Phenolic Pulley with a bearing center would work fine. The anchoring point of either cable will give you your differential pull /Push lengths.

[@rustyheaps]

On the throttle...what about the end of the engine cable having a 180 degree cable guide, and the cockpit control being a rod which is attached directly to the engine cable. Many fewer connections/wear points. The rod, as it's pushed in, pulls open the throttles. The engine cable guide would be attached to mounting plate that also had a guide bushing for the rod.

[@KitfoxPilot]

Nice video Brian. One question your airbox mount you are adding on needs to go back to the engine doesn't it because the engine is rubber mounted to motor mount and you will get different movement between the engine and the mount?

[@422904]

I am impressed with the work up to the point of the throttle.... I would not want my throttle to default to closed... bad idea! It’s an airplane it needs to be flying with power, if it defaults open, just shut off the fuel, either with mixture or fuel shut off. It’s not a car that you can pull over to the side of the road, it would be applicable so you don’t run into a fire hydrant. Please get rid of that throttle contraption, and re-bracket your throttlebody to receive it from the other end, and have a normal throttle, Make it airworthy! I mean you the best and would trust my family in the airplane all day long if you can make the normal push pull, Thanks

[@thomasaltruda]

Wow, that carbon looks great after the sanding! That was the right thing to do to sand the high spots, vs filling the low spots.. I don’t think I would have realized that the peel ply was causing the epoxy to pull to the surface like that!

[@jvftools]

That cable going back to the engine is indeed going the start cracking, make a hinge on the fixed peace where the spring is. to much friction going on there

[@kevindrapola7838]

Looks great your content is also great that plane will be awesome !!

[@Stromzilla]

I like your comments on changing the profile around the radiator...excellent and will look much better but do it later.

[@MRJSWORKSHOP]

Hi Brian , your plane is coming together and looking good. I am learning lot.👍🏻👍🏻👍🏻👍🏻👍🏻

[@eiselbay]

loving the progress man, great work!

[@kylanlarsen6752]

Love this project and engine choice!

[@FlyingNDriving]

Enjoy the holidays with the family. We can wait. I enjoy your creative solutions to tackle these little hiccups

[@ec-norsemanzero-drake7031]

Keep up the great work Brian... so glad to see the air box coming together and other amazing thing you have done. Almost called to chat, the radiator thing was getting to my sense abilities. Haha Back to work!

[@dustinalexander4620]

Brian, I stumbled into your channel from the other stol guys. The first vid I watched I wasn't too attached. Well after a couple and a subscription, I found it hard to wait till the next drop. I live your vids and for the last couple months watch your updates as soon as you drop them. P.s. You better beat Mike Patey to FIRST FLIGHT. I know you can do it....! I'm cheering you on. Do It, Do It, Get To Work.....

[@BowenAero]

It will be close. We have been text back and forth egging each other on.

[@jimmonti]

Love your progress with the plane. I am a mechanical engineer, and I have a problem with the way you terminated the throttle cable on the toggle bar. My dad was an aeronautical engineer and not protecting the repeated bending of a push-pull wire is asking for problems, in the future. I agree with the double clamp idea (very good). Can I offer a pivot design that gives you the double clamp and a smooth pivot to protect the cable. The other end of the toggle bar needs help too. Glad to give you free CAD for each end , as something to consider.

[@BowenAero]

I to have considered how to create a pivot on the double clamp side, but unfortunately when a mock up was made, it would pivot instead of pushing the lever arm. A rigid mount on the push side is necessary.

[@jimmonti]

@@BowenAero Brian, Evening. I would like to send you a CAD file (in SolidWorks or in a STP assy), with my thoughts about the cable clamps. Just an idea of how to connect the 2 cables. Let me know. Jim

[@outcold1982]

Looks great! Nice work so far!

[@durlovborgohain9871]

I'm very exciting.... I am Watching each and every episode #One of your Subscriber from India.

[@JPascal61]

Nice work Bryan. Fun to watch. Thanks for posting.

[@RJK50]

Can you remove the spring on the throttle bodies? Love your videos and keep up the nice work.

[@maleficentcop2752]

Ok so I know he described why the spring was needed....I mean with the tensioner why was it needed ?...I guess I didn't understand...🤔

[@BowenAero]

I have discussed that idea with some other APEX builders. I like the idea of removing the throttle body spring completely and having it work more like a Lycoming throttle linkage.

[@alaskanstoneguys]

Great job it’s about persistence man Keep it up 👍

[@Stromzilla]

For a clear coat on the air box, how about a coat of epoxy brushed on followed with a heat gun to flow it out.

[@countryflyer4536]

That body work stuff is the worst, I'm thinking you would agree...looking good!!

[@maleficentcop2752]

Yep it's sure time consuming.... Butt in the end it's worth it...👍👍👍

[@Project2Aero]

Looks sweet!

[@briand3837]

For the throttle - could you place a cam (like on a compound bow) above the linkage to reverse the throttle?

[@TheRedbeardpirate]

For your throttle would there be enough room to mount a bellcrank to pushrod throttle link under the air box? You could adjust the ratio of the bellcrank arms and get a full push type system without the need for flexing the parts to such a degree.

[@BowenAero]

There is a guy working on a straight push setup that maybe an option in the future

[@TheRedbeardpirate]

@@BowenAero cool. The cowl and airbox turned out great! Thanks for sharing

[@patrickdavey9692]

I would put a pivot point where the return spring attaches, the potential for wearon the cable pulling to one side or cutting into the sheath.

[@scottwoodall4622]

Hey Brian get work I have watched all episodes, just wondering about how many hours do you have in this build?

[@BowenAero]

I haven’t been keeping track. I started out tracking and just forget to do it.

[@thomasaltruda]

Instead of using that Cessna style cable, how about using a throttle lever on the side like a Cub or RV-4 or RV-8? Less connections, just the lever for your hand, and connect the throttle cable to the lever under the pivot like you talked about, and get rid of the push cable with the connections? I would also set up the spring so if the cable breaks, it goes to full throttle! Not idle! Could you imagine having a failure if the throttle fell to idle at a critical point on takeoff? I would always rather it fails to full power, the. You can always shut the motor with the ignition or fuel and dead stick it in when you are ready! Sure, if it’s a car or snowmobile, fail to idle is ok, but an aircraft, no way.. fail to go, not to stop.

[@russellsmith3825]

He mentions a fail to mid throttle as a possible setup, this engine will rev extremely high and could go red line

[@JailDoctor1]

Cable linkage. Could you have acheved the same results by attaching throttle cable from the backside of the throttle body with a single miniture throttle lever extension. Add a mounting tab w/bolt holes on the air box when you add airbox support. . Less weight. ..........or not. Hard to see at 1080p. KJZI

[@russellsmith3825]

Do you think the knob side throttle cable will fatigue and break with that much flex? Would it be better to pivot in the bell crank?

[@BowenAero]

Possibly but with the flex in the cable you loose some of the action with a swivel type clamp where the point will swivel instead of push the lever.

[@bretmuldner]

I want mine to fail to were I can fly home safely...

[@Shreyam_io]

LOL, Please edit your About section... I went there to know your name😅😅

[@rixtrix11]

Bryan Bowen, of Bowen Aero, LLC

[@f.dt.f3965]

why don't you let the cable mount pivot where it mounts to the reverser arm so it dosen't bend the cable as bad where it goes into the housing or cable jacket ? be easier on cables....i would let both pivot if possible those snowmobile cables aren't as tough as a guy would like... I've had more than one break

[@danieldrinkwalter2393]

Did you think about using a throttle quadrant? Thy have models that can be reversing and non-reversing. Then you would just need to fabricate a mount for the throttle quadrant. www.aircraftspruce.com/catalog/appages/hbthrquads5.php