[grosbeak]

Servo test fit (sort of).




I've marked the locations for the (E)ars and the (H)orns... those will be cut out next.

[stegl]

Originally Posted by grosbeak

I will have another look at the horizontal stabilizer... I must admit that I am intrigued by this idea. I'll have to decide before I go any further with the build, though... installing the hstab and the joiner are the next step!

I was a little surprised to see how pricey these are, but then I noticed that they are digital, which I do not need. Is there an analog alternative?

Yes, agreed the airtronics 94761 are not cheap ;exactly . A consideration with the large elevators is flutter when flown fast. As they say with jet turbines it is not always the power that is needed but flutter control is a big concern also. I know we won't have jet speeds here but flutter can develope even at slower speeds.

The hs125 should do the job when smaller amounts of up or down control are needed but when you start to get into larger throws say for more extreme or aerobatic flying, then the 125's may lock up and stall out with not very nice results. I will put it another way..... Do a calculation of the all up cost of your aircraft and then decide if the saving of 50 or 60 bucks is worth it ; if so then go for the 125's.....regarding digital servos that is pretty much all that Airtronics make as once you use them, no going back to analogues, at least I didn't ......so many advantages. Please don't take this as criticism but just other considerations to think about. I definitely like your decision to go with the twin elevator servos. Oops forgot one more.... Even if operating the servos with 6v go with heavier servo wire to the tail to minimize voltage drop.... Like use minimum 22 gauge servo extension wire and that is available at Thunderbolt R/C for sure.

[stegl]

Also you do a real bang up job on the pictures . Been reading the manual regarding heir servo selection and something does not really compute..... They recommend min 50 oz servos min but yet the servos listed are 130 oz at 6v... That's over 250% increase over the 50oz in. Looking at the pictures the flaps, elevators and rudder look pretty darn big with lots of throw and am thinking that 50 oz servos will never cut it. Might be worth it to contact RCGuys and clarify that with them as the 50 oz could be a misprint?

Maybe the hs225mg might be a better choice as according to your measurements, they should fit and they have torque up closer to the Airtronics 94761's...

One more question, have you done a dry fit with the wings pushed onto the wing tubes to see if they are horizontal with the horizontal stab before glueing ? Have had past arf's where slight adjustment needed with the H.stab to make it work as with most wing on tubes don't easily allow any adjustment.

Can't wait to see a maiden video.

[grosbeak]

I've been turning the next step over in my mind but am not yet certain of the conclusion: How to route the servo wires? I will be splicing in an extension of the required length and I would like them to be at least semi-accessible in the event that I have to change out a servo.

Remember that this horizontal stabilizer is a single piece. My best idea so far is to make a small hole in the part of the leading edge that will be inside the fuselage when the stabilizer is glued in place. I don't think it'll be much trouble to route the wires from the servos to the hole; I would:

1. Tie a string to the extended servo wires and tuck them inside the stab.



2. Feed the string through the fuselage as I was sliding the stab into place, and




3. Then slide and glue the stab into the fuselage. Pull the servo wires through with the string.




If I had to change a servo I would do the reverse... tie a string to the connector before removing the servo. Leave the string in place to connect to the new servo.

Other suggestions welcome!

[grosbeak]

Originally Posted by stegl

Also you do a real bang up job on the pictures . Been reading the manual regarding heir servo selection and something does not really compute..... They recommend min 50 oz servos min but yet the servos listed are 130 oz at 6v... That's over 250% increase over the 50oz in. Looking at the pictures the flaps, elevators and rudder look pretty darn big with lots of throw and am thinking that 50 oz servos will never cut it. Might be worth it to contact RCGuys and clarify that with them as the 50 oz could be a misprint?

Maybe the hs225mg might be a better choice as according to your measurements, they should fit and they have torque up closer to the Airtronics 94761's...

I have contacted them and they confirm 50 oz-in servos. Remember, that's for BOTH elevators. I have 49 oz-in for EACH elevator - I think it'll be plenty. All of my other servos are closer to 100 oz-in.

One more question, have you done a dry fit with the wings pushed onto the wing tubes to see if they are horizontal with the horizontal stab before glueing ? Have had past arf's where slight adjustment needed with the H.stab to make it work as with most wing on tubes don't easily allow any adjustment.

I have not... but I will now! Thank you!

Can't wait to see a maiden video.

Hope you're patient... I'm forecasting a spring maiden!

[stegl]

OK If you feel comfortable with the two 49oz servos then go for it. I just have reservations when on one hand they say that 50 are ok ;on those big surfaces and then they go and use 125 +- oz servos. In my mind that's just too much of a difference.
rather than cut a hole at the leading edge for servos wire access; I would go with the hole in the bottom 1/2 inch oval hole should be sufficient rather than leading edge. More room to work. Also if or when necessary to change an elevator servo ; just unplug the elevator servo extension at the receiver with string attached and then remove the servo/cover ; pull out until you access the male/female plug , remove locking heat shrink or what ever means used to keep them together and change. Heat shrink works good or even couple of wraps and tie some string thru the wires and around the plug work great for free. You have great ideas for running the string.

Hope you don't mind the suggestions... LOL.

The other thing I noticed that they use bent aluminum main gear and at 12-14 pounds AUW not so sure. My Top Flite Cessna 182 60 kit had it and after a summer of grass landings didn't hold it's shape well and lost any spring. I was very fortunate to be able to get the fibreglass landing gear that they put in the same thing but ARF version and all I can say is WHAT A GREAT IMPROVEMENT and scale too ! I also got their wheel pants while I was at it. They absorb ground shock 10 times better than the aluminum and make you look like a pro on landing. If you want, I can take some measurements here for you to see if they might fit. They do have the foreword rake as well . Come painted white.

[grosbeak]

Originally Posted by stegl

Also you do a real bang up job on the pictures . Been reading the manual regarding heir servo selection and something does not really compute..... They recommend min 50 oz servos min but yet the servos listed are 130 oz at 6v... That's over 250% increase over the 50oz in.

Could you tell me where you're getting this information from?

Originally Posted by stegl

rather than cut a hole at the leading edge for servos wire access; I would go with the hole in the bottom 1/2 inch oval hole should be sufficient rather than leading edge. More room to work.

1/2" hole in the bottom of what... the elevator? Leaving the wires outside?

Also if or when necessary to change an elevator servo ; just unplug the elevator servo extension at the receiver with string attached and then remove the servo/cover ; pull out until you access the male/female plug , remove locking heat shrink or what ever means used to keep them together and change. Heat shrink works good or even couple of wraps and tie some string thru the wires and around the plug work great for free. You have great ideas for running the string.

There won't be an extension to unplug - I will use solder to splice the extension wire into the original servo wire.

Hope you don't mind the suggestions... LOL.

Not at all!

The other thing I noticed that they use bent aluminum main gear and at 12-14 pounds AUW not so sure. My Top Flite Cessna 182 60 kit had it and after a summer of grass landings didn't hold it's shape well and lost any spring. I was very fortunate to be able to get the fibreglass landing gear that they put in the same thing but ARF version and all I can say is WHAT A GREAT IMPROVEMENT and scale too ! I also got their wheel pants while I was at it. They absorb ground shock 10 times better than the aluminum and make you look like a pro on landing. If you want, I can take some measurements here for you to see if they might fit. They do have the foreword rake as well . Come painted white.

Yes, please do take the measurements... and thank you.

[grosbeak]

While I'm mulling over the elevator servo wire routing, I took a little time to finish cutting the openings in the horizontal stabilizer. I started with a 5/64" brad point bit.




When drilling through covering I spin the bit by hand.




First the bit spins counter-clockwise a few turns... this removes the covering over the hole without tearing it up. Then clockwise to drill the hole.




Covering removed.

[grosbeak]

The hobby knife with #11 blade works very well for cuts with the grain. For crosscutting I prefer the mini keyhole saw.




A little cutting, a little ironing and a little cleanup and the openings are ready.




I thought it would be handy to get some detailed servo dimensions.




The plan is to have the servo mounted flush with the surface of the elevator. To do this I will glue a frame into the bottom of the hole with standoffs for the servo lugs to mount to.

[grosbeak]

I took a little time to correct what I could about the nose gear. I was looking forward to having proper sprung nose gear on this plane but I'm disappointed with what's supplied for the following reasons.

1. Cheap, banged up aluminum
   
2. Misaligned scissors
   
3. Spring way too stiff
4. Cheap, ill-fitting, corroded hardware
   
5. 6-32 (Phillips!) bolt and nut for axle
   

Item 1... well, I'm sure most full-scale Cessna 150s have less than pristine nose gear. I can live with that.
Item 2... Nothing I can do without a metal shop. I'll learn to live with that too.
Item 3 may be fixable with a softer spring... I'll have to look into that.
Items 4 - done (see below)
Item 5 - next on the list (coming soon)