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What a difference a prop can make

Arcfyre

Elite member
#21
To get the cub to fly sweet and take off/land just as sweet you need to firstly consider the extra drag of the floats and so a bit more thrust is highly desirable.
Next there is the weight to consider and so you may need a slight bit more main wing incidence, (not too much though(.

And finally the floats should have a "Step" to help break surface tension and allow the plane to rise up on the "Plane" when running at speed over the water. The step is the point of contact with the ground in the same manner that wheels are the point of contact with the ground for a normal ground take off. The Step should be slightly FORWARD of the planes CG for a nice take off.

The biggest issue with flying off of floats is that they are fitted incorrectly and often too far to the rear. In the extreme if the step is too far aft the plane can somersault nose first into the water on landing or even on take off.

Just what I was taught!

Have fun!
I was using the FT designed floats for the scout and cub. The main issue I had with them was that the stock landing gear attachment did not set the correct incidence angle of the aircraft relative to the floats. The nose of the aircraft was too low and it was very difficult to take off, even once planing on the step.

I increased the size of the foam holder for the front mount of the landing gear and it gave me the proper incidence angle. Handling was much improved and I've had several successful flights.

The reason I like the scout better than the cub for floats is just because I feel the scout flies better to begin with, and is better able to cope with the additional drag of the floats.
 

Sero

Elite member
#22
And finally the floats should have a "Step" to help break surface tension and allow the plane to rise up on the "Plane" when running at speed over the water. The step is the point of contact with the ground in the same manner that wheels are the point of contact with the ground for a normal ground take off. The Step should be slightly FORWARD of the planes CG for a nice take off.

The biggest issue with flying off of floats is that they are fitted incorrectly and often too far to the rear. In the extreme if the step is too far aft the plane can somersault nose first into the water on landing or even on take off.

Just what I was taught!

Have fun!
I'm not sure about the Sea Angel or the Otter, both the Sea Duck and the floats for the Cub have the step 1/2" behind the CG.
 
#24
Ok, so I've been scratch building FT designs for exactly a year now. It's been one heck of a ride, and I've learned a huge amount about this hobby.

I've had a love/hate relationship with the simple cub since day 1. My first ever thread on this forum was about my cub. Check it out here if you're interested. Long story short, it was ridiculously overweight, with an oversized battery and prop, made of the wrong material and built as a 3 channel. Anyone that knows about the cub knew that this thing had zero chance of flying like the one in the build video. Anyway it didn't last more than a few flights before it was destroyed.

I didn't let it get me down. I got a speed build kit for a Storch and a simple soarer, built my flying skills for several months, and after going through a few mini mustangs and discovering a love for flying wings, I circled back to a simple cub.

I had learned a lot by now, especially about scratch building. I had the proper DTFB material, and was much much cleaner with my cutting out. I was also much more careful with gluing. I wouldn't call myself a professional builder by any means, but definitely proficient. Anyway, with my level of skill at the time, I felt confident to try the cub again.

I built a nice clean airframe and wired it up as a 4 channel. I used a much more appropriate motor, and a much smaller 1000mah battery to keep weight down. It was adequately powered and well within specs for AUW. It should fly just fine, right?

Well, it didn't. Even with a stabilized RX I just couldn't keep the stupid thing in the air. I was at the point where I could thread needles with my Storch or Versa wing, but I couldn't fly the cub? A trainer? Really? The fault must lie with the airplane.

After a particularly nasty landing which removed the landing gear and most of the nose, I scrapped that airframe and sat down to do some reading. I finally discovered that I wasn't the only one who had issues with the cub. I want to give credit to @Hai-Lee for finally mentioning that the wing incidence angle needed an adjustment before the plane would fly. I steeled my nerves and sat down to build another simple cub.

I built this one as light as I possibly could. I modified the wing incidence angle and even stretched the wingspan a bit to give it more lift. I powered it with a tiny little lightweight motor and used my smallest battery possible. I used a "soft" 8x4.5 slowfly prop and went for a maiden flight.

The thing barely flew with that power setup. No balls whatsoever. Totally unable to cope with any wind. Another disappointing cub. Part of the problem was that at any power setting above 60%, the prop would overspin and flatten out, basically producing no thrust at all. This basically made the plane unflyable, UNTIL yesterday I put an APC 8x3.8 slowfly prop on.

Oh my word, what a beautiful flying airplane! Just about silent, uses barely any power, and has a great rate of climb if it needs it. Lands in a few feet and can fly at walking speed. Can handle a little wind too. I'm blown away. Finally, I have a cub that flies!

It's only taken me a year, but I finally have a simple cub that flies. I'm thrilled lol. I'm blown away the difference that the right prop can make to the flyability of an airplane.
 
#25
Ok, so I've been scratch building FT designs for exactly a year now. It's been one heck of a ride, and I've learned a huge amount about this hobby.

I've had a love/hate relationship with the simple cub since day 1. My first ever thread on this forum was about my cub. Check it out here if you're interested. Long story short, it was ridiculously overweight, with an oversized battery and prop, made of the wrong material and built as a 3 channel. Anyone that knows about the cub knew that this thing had zero chance of flying like the one in the build video. Anyway it didn't last more than a few flights before it was destroyed.

I didn't let it get me down. I got a speed build kit for a Storch and a simple soarer, built my flying skills for several months, and after going through a few mini mustangs and discovering a love for flying wings, I circled back to a simple cub.

I had learned a lot by now, especially about scratch building. I had the proper DTFB material, and was much much cleaner with my cutting out. I was also much more careful with gluing. I wouldn't call myself a professional builder by any means, but definitely proficient. Anyway, with my level of skill at the time, I felt confident to try the cub again.

I built a nice clean airframe and wired it up as a 4 channel. I used a much more appropriate motor, and a much smaller 1000mah battery to keep weight down. It was adequately powered and well within specs for AUW. It should fly just fine, right?

Well, it didn't. Even with a stabilized RX I just couldn't keep the stupid thing in the air. I was at the point where I could thread needles with my Storch or Versa wing, but I couldn't fly the cub? A trainer? Really? The fault must lie with the airplane.

After a particularly nasty landing which removed the landing gear and most of the nose, I scrapped that airframe and sat down to do some reading. I finally discovered that I wasn't the only one who had issues with the cub. I want to give credit to @Hai-Lee for finally mentioning that the wing incidence angle needed an adjustment before the plane would fly. I steeled my nerves and sat down to build another simple cub.

I built this one as light as I possibly could. I modified the wing incidence angle and even stretched the wingspan a bit to give it more lift. I powered it with a tiny little lightweight motor and used my smallest battery possible. I used a "soft" 8x4.5 slowfly prop and went for a maiden flight.

The thing barely flew with that power setup. No balls whatsoever. Totally unable to cope with any wind. Another disappointing cub. Part of the problem was that at any power setting above 60%, the prop would overspin and flatten out, basically producing no thrust at all. This basically made the plane unflyable, UNTIL yesterday I put an APC 8x3.8 slowfly prop on.

Oh my word, what a beautiful flying airplane! Just about silent, uses barely any power, and has a great rate of climb if it needs it. Lands in a few feet and can fly at walking speed. Can handle a little wind too. I'm blown away. Finally, I have a cub that flies!

It's only taken me a year, but I finally have a simple cub that flies. I'm thrilled lol. I'm blown away the difference that the right prop can make to the flyability of an airplane.
The first plane I built was the simple cub, I've just flown it for the first time and it flew great, I ordered the power pack b that came with 2212 1050kv motor, 35amp esc, and 9x4.5 props, very stiff props, I never used over 60% throttle, plenty of power, my problem is that I break a prop every time I land, getting expensive,
 

mayan

Legendary member
#26
The first plane I built was the simple cub, I've just flown it for the first time and it flew great, I ordered the power pack b that came with 2212 1050kv motor, 35amp esc, and 9x4.5 props, very stiff props, I never used over 60% throttle, plenty of power, my problem is that I break a prop every time I land, getting expensive,
Try APC props if you haven’t already they work great for me and tend to have a long life span.
 

Bricks

Master member
#27
The first plane I built was the simple cub, I've just flown it for the first time and it flew great, I ordered the power pack b that came with 2212 1050kv motor, 35amp esc, and 9x4.5 props, very stiff props, I never used over 60% throttle, plenty of power, my problem is that I break a prop every time I land, getting expensive,
When landing at the last moment try and flair the plane and kill throttle at the same time so it flops down more then lands.
 

moret

Well-known member
#29
The reason I like the scout better than the cub for floats is just because I feel the scout flies better to begin with, and is better able to cope with the additional drag of the floats.
Yes, Yes, and yes again. Also the scout is easier to get off the ground. You may need some right rudder but that will keep it from ground looping. ON both, You also need slow throttle advance and full up elevator if flying from grass until you get some speed up
 

PoorManRC

Master member
#30
THANK YOU!! This was very educational. I just finished, and CRASHED colossaly, my "Simple" Cub. I checked, checked, and went over the whole thing again before the Maiden...
But IGNORED a catastrophic failure of the Rudder!! I had creased it slightly, installing a Tail Wheel Wire...

~ I should note here that I had done quite major modifications to it, to attempt to iron out some of its shortcomings. Particularly its propensity to NOSE OVER on Landings. Not even the Bix could land it without Nosing Over!! 😲😜 ~

I never even got the chance to test my extensive research...
After 2 minutes of some beautiful, smooth Flight, the Rudder buckled, locked Right, spiralled, and nose dived into HARD Soil. 😭
IMG_20190813_150523.jpg

I was running a slightly larger than C Pack sized Motor (2218-10), 1800 MAh 3S Batry and a 10x4.7SF APC Prop. Being a former 1:1 Pilot and Race Car Driver, I always like to err on the overpowered side. You can always Throttle DOWN, but if you get in a jam, and can't increase Power that you DON'T have, that's a whole other issue.

I even listened to the great advice of @Hai-Lee and added a bit over 2% of up Incidence to the Wing.
She was 780g AUW. Yes heavy, but very balanced. Quadruple checked that too!

The main problem was MY stupidity and over anxiety to PROVE to a couple of other People my proof of concept - INSTEAD of Flying for the joy and satisfaction of Flying for Myself!!

Like you, I'm not giving up... Just stepping back, reviewing and licking my wounds before trying again.

I'm building and Flying the Scout next. The consensus is that it's just a better flying Aircraft!

Also, a question for anyone... I'm not going to ASSUME that I got the Balance perfect! This is a quirky Bird.

WHERE is the optimal Balance Point on the Wing for YOU?
 

PoorManRC

Master member
#32
On any plane I build, even an exact FT 1on1 build I aim for 1/3 from the wing LE. Don’t know if it’s right or not but it tends to work for me so far :).
I like that figure.... 😉
My Cub was marked at about 20-25%.
Maybe I WAS a little Tail heavy after all?? 😲
 

mayan

Legendary member
#33
Another thing if I do end up a bit past it I’ll just toss in a bigger battery. I don’t like the idea of blast weight any where on the plane for CG balance. Just me.
 

PoorManRC

Master member
#34
Another thing if I do end up a bit past it I’ll just toss in a bigger battery. I don’t like the idea of blast weight any where on the plane for CG balance. Just me.
I agree with that. Being in RC Ground first.... I've got Batteries from 1800 to 8000 MAh!! 😲