Carl Goldberg Ranger 30

[TooJung2Die]

Changes needed, advice appreciated.

This is my first attempt at airplane design. That's why I started with a proven airplane. It has become apparent that designs that are good for free flight don't always work well with RC without modification. I got it up and flew it around a bit. Getting it back down safely was more luck than skill. It flies like it is excessively tail heavy. It wants to point the nose towards the sky and getting it level wasn't easy. Keeping that attitude was impossible.

The CG was at the front of the wing spar. The original assembly instructions for the balsa Ranger show the CG further rear than that. If it needs more weight in the nose then more weight it is.

The wing's incidence angle is less than the original plans. It is currently 2 degrees relative to the horizontal stabilizer. Should I make it zero degrees like the Tiny Trainer? I guess I can try shimming the trailing edge of the wing to see.

I had the motor set to 4 degrees right angle thrust. No down thrust. Should I angle the motor down as well as right?

The vertical stabilizer and rudder probably need to be bigger. Rudder response was like it was on a delay. Nothing, nothing, then it began to turn. Could be because it's tail heavy too?

I'm building the third fuselage. This one has a vertical stabilizer 5" tall instead of 3.75". I think the taller v-stab even looks better. The motor is installed with 4 degrees right and down thrust.

I'm going to use the old fuselage and wing as a chuck glider to experiment with the CG and incidence angle. I hoping if I can get those worked out then all I should have to figure out is the motor thrust angle?



Too gusty to fly even a chuck glider so I'm working in the shop.

Jon

 

[TEAJR66]

TooJung2Die, I would try the incidence at zero and shim from there. The down thrust is more important than the right thrust. The airframe will resist torque roll at cruise once airflow is established. The right thrust helps during accelerations and helps the trims stay constant through a wider speed envelope. The down thrust is to counter the offset of the thrust line from the drag line. The drag is constant during cruise and specially exaggerated during acceleration. Any where from 3 - 6 degrees down thrust is a good start. I looked at the plans briefly, and no thrust angles jumped off the page at me so I might need to look harder.

When it went nose up, was that under power? How did it fly or glide when you powered off?

Looks like the new fuse has a longer nose. If so start at about 3 degrees down thrust.

If you have the resources, stick with it. I would really like to see you get this worked out.

 

[TooJung2Die]

TooJung2Die, I would try the incidence at zero and shim from there. The down thrust is more important than the right thrust.
I looked at the plans briefly, and no thrust angles jumped off the page at me so I might need to look harder.

There's right thrust drawn in the plans copied from the mini-power pod. No down thrust is indicated. That is dependent on how the builder glues in the firewall.

When it went nose up, was that under power? How did it fly or glide when you powered off?
Looks like the new fuse has a longer nose. If so start at about 3 degrees down thrust.

It was uncontrollable until I backed way off on power. The new firewall has 4 degrees down thrust, 4 degrees right. I remember the Cox .020 engine on the free flight was pretty drastically down and to the right. I didn't get to test the glide. I was too focused on getting it back towards me and on the ground in one piece. The nose length hasn't changed. It's already nice and long so CG adjustment shouldn't be too hard.

Your input is appreciated.

Jon

If you have the resources, stick with it. I would really like to see you get this worked out.

I'm a tinkerer. Time at the workbench is as much fun as flying.
So many variables. I'm sure using an FT airfoil wing changed the flight characteristics. The balsa wing was almost flat with very little airfoil. I'm going to focus on getting the glide nice then tackle the power puzzle.

 

[TooJung2Die]

Glider

I glued 46gr of washers in the nose which balanced the glider at the center of the wing spar. Nice flat glide without stalling, tipping or diving. That tells me I probably had the CG and incidence angle right. I weighed the airplane electronics and got 18gr motor, 48gr battery, 22gr ESC and receiver, for 88 grams total. There's more than enough weight to get the nose down and that's not counting the landing gear. Let's put this together with 4 degrees of down and 4 right thrust and see what happens next. The servos are going on the outside of the fuselage this time with z-bends in the push rods for easier adjustment. I'll make a pretty one after it flies well.

 

[TEAJR66]

Good luck. Keep us posted.

 

[jh1985]

It looks good so far. I might build one this week and see if i can help figure it out. My rule is cg First then Thrust angle. I do know with planes this size adding a bigger rudder/elevator is usually a must. You might try a under camber airfoil like old fogey style. just score cut it and glue the cuts while bending to try another airfoil

 

[TooJung2Die]

It looks good so far. I might build one this week and see if i can help figure it out. My rule is cg First then Thrust angle. I do know with planes this size adding a bigger rudder/elevator is usually a must. You might try a under camber airfoil like old fogey style. just score cut it and glue the cuts while bending to try another airfoil

I too began to think the problem is the wing. Since the balsa original was almost flat I made a KFm2 airfoil wing with 2" dihedral. I glide tested it all up weight with the CG about 1.5" behind the leading edge. Nothing wrong with the glide when tossed but it was not as flat as the original.

Under power I got it up and kept it up. The KF wing works. Yay! It wanted at least half throttle. For some reason it was more difficult to control when under low power or gliding. I didn't like the rudder behavior. Anything more than a very gentle turn created a rapid descent to spiral dive. It likes to climb under power when flying straight and needed down elevator to maintain the same altitude. But it was finally flying and didn't have the nose up tendency anymore. It seemed pretty speedy with a 5" prop.

Towards the end of the battery life things began to go south. The motor began quitting briefly. Then longer cut offs. Finally I lost all connection with the airplane. It spiraled nose first into the ground, breaking off the nose right in front of the windshield. I won't be buying used receivers off eBay anymore. Lesson learned.

I'm done with this airplane for the time being. I have the 3ch and 4ch Tiny Trainers. I need much more practice. I suck at video games and RC flying resembles a video game with real life consequences. BTW - How do you take video of the airplane? I need both hands while flying and don't have a photographer friend to help.

I'll attach the plan for the KFm2 wing and taller vertical stabilizer. It's a pretty looking model airplane and deserves another go at working out the bugs in the future.

View attachment Ranger wing KF.pdf
View attachment Ranger vert stab long.pdf
Jon

 

[TooJung2Die]

Ranger RC

It's good to step away from a problem and think about it. Why do the Tiny Trainers fly so well and a pretty airplane like the Ranger 30 is so hard to keep in the air?

I borrowed the airfoil from the Tiny Trainer glider wing and made a 29.75" x 5" constant chord wing for the Ranger. Then I increased the size of the elevator and rudder. I also added 3/8" to the width of the fuselage so you don't have to cram the batteries in there. The wing is set with zero incidence. The DYS BE1806 2300kv motor is mounted straight ahead without any angle. CG is at the leading edge of the wing spar.

It looks a bit different now but it is still a nice looking airplane. I can't call it a Goldberg Ranger 30 anymore. Ranger RC will do I suppose.

Wing:


I used a gift card to protect the bottom of the fuselage where the landing gear are mounted.
Fuselage and landing gear:


Two views:




It had it's maiden flight today and I'm very happy. This airplane flies like I had hoped it would from the start. It is very steady and easy to control. It is as easy to fly as the 3 channel Tiny Trainer if not easier. It will putt around with a 2s battery at half throttle and a 6x4 prop is excellent. I almost wish I had this as my first airplane though the Tiny Trainers were great for that purpose. I ran through four batteries, flew for an hour and took it home without a dent or scratch on it. That is remarkable for this newbie RC pilot! I hardly ever go flying without breaking something.

The motor will benefit from some angle to the right like other small airplanes. It banks slightly left with the motor straight but some right rudder trim will fix that.

I have the first two flights recorded on video. I'll need to learn how to post them so you have proof it flies. I'll upload the new PDF plans too if anyone is interested.

Now that it has proven itself it is time to give it some color. Onward and upward.

Jon

 

[TEAJR66]

Congratulations. I am glad to see that it worked out. That three break wing performs very well. I will be looking for the flight video.

I can't wait to see what you do next.

 

[TooJung2Die]

Added some colored and metallic tape.



Jon

 

[Maingear]

Man that looks great!

Justin

 

[TooJung2Die]

Ranger RC Plans

Here are the plans for the current version. I like to print out the parts separately. Just print them poster size 100% in Acrobat and try landscape and portrait orientation for the best fit.

The notches for the tail feathers in the fuselage aren't exact. You'll have to lengthen them a bit after you assemble the fuselage body. No biggy.

Please make any changes you think will help and let us know how it works.

I see ailerons on this in the future.

Jon

View attachment Ranger fuselage zero incidence wide.pdf
View attachment Ranger horiz stab wide.pdf
View attachment Ranger vert stab wide.pdf
View attachment Ranger wing constant chord.pdf

 

[TooJung2Die]

Maiden flight video

Here's the video of the maiden flight. Sorry about the inane commentary. Talking to myself. Again.

Jon

 

[TEAJR66]

Here's the video of the maiden flight. Sorry about the inane commentary. Talking to myself. Again.

https://youtu.be/7zjE9bUffGM

Jon

Good job brother. There will be no stopping you now. Enjoy.

 

[TooJung2Die]

Thanks, Tommy. I flew it again today. It really rips along with a 3s battery. A 2s is plenty fast enough for my ability. It weighs 9 oz AUW.

Uploading the video to YouTube destroyed the video quality. It is so blurry you can't make out the airplane in half the video. It looks crystal clear on my computer screen and really bad on YouTube. I'll have to find out if there's a way to prevent this. The original was recorded on an iPhone so it's a MOV file.

Jon

 

[TooJung2Die]

Better video

I converted the original MOV video to MP4 before uploading it a second time. There is no way to replace a video on YouTube so I deleted the first blurry one. The new one is clearer but just as boring.

 

[Dreamwalker]

I just caught this tread, WOW!! I too recently downloaded the Carl Goldberg plans from Outerzone to do this very project myself, but you beat me to it. Excellent job sir! Now the only thing left is to build one of these beauties.

 

[TooJung2Die]

Trimmed out, second flight

I just caught this tread, WOW!! I too recently downloaded the Carl Goldberg plans from Outerzone to do this very project myself, but you beat me to it. Excellent job sir! Now the only thing left is to build one of these beauties.

Thank you sir! I can't wait to see your version. This is all new to me so it's a work in progress. Every time I look at the plans I find something that can be improved.

I would like to have kept the tapered wings. I like they way they look. But from what I read, tapered wings are more prone to tip stalling. I think that's a big part of the troubles I had with the first three Rangers.

Here are the last two minutes of the second flight after trimming the rudder and elevator. You can tell I'm happy and relieved with how it's flying. Persistence paid off.

Jon

 

[TEAJR66]

Ailerons next?

 

[TooJung2Die]

Ailerons next?

Enabler!