Enlarged 104" Kadet build; flap, dihedral and aileron questions.....
02-08-2015, 04:31 PM
#1
Enlarged 104" Kadet build; flap, dihedral and aileron questions.....
I'm seriously considering building an enlarged 104" to 110" Kadet. It will be a 4 channel with ailerons, wing-tube, and I'm guessing about 15-17 lbs dry weight, and powered by a G38 or DLE 35.
1)
I'm wondering how much total dihedral to build the wing with. While I want the plane to still be a fun and stable kind of a weekend flier (or why build a Kadet?), I'd also like to be able to do modest aerobatics and get the plane to at least roll easy and do other simple stuff without losing it's "kadet" charachtersistics. So how much dihedral would be a good compromise? (To avoid confusion if you tell me 6° dihedral, I'll take that to mean 3° for each wing half.)
2)
a) Should I bother putting flaps in a Kadet?
b) If you suggest I add flaps, then should I consider making barndoor style ailerons?...... since I will be losing aileron length when flaps are installed.
3) Solid strip ailerons or built-up from out of the wing?
Thus far, I have never built a plane larger then my 85" Big Bingo or an enlarged 89" AstroHog .Both had solid balsa strip ailerons. I made the aileron for the Hog by shaping a solid 24" rectangle of balsa block into the usual triangular aileron stock configuration to blend in with the contour of the rest of the wing. The Big Bingo came with solid aileron stock. My question is whether I should just build my 104"- 110" Kadet wing as if it is a 3 channel plane with no ailerons. As I'm building the wing, I will add the lumber into the aileron section of the wing and build the ailerons into place. This way they are the same contour of the wing, and all I need to do is cut them free of the wing and install hinges. Of course I will put the necesary extra cross pieces beforehand and add other balsa pieces in there to beef it up to resist the aero- dynamic stresses. What I'm describing is very similar to the construction used when doing barndoor style ailerons as seen here; http://www.angelfire.com/indie/aerostuff/kadflap.htm
Any other recommendations or input is appreciated and will be taken into consideration for the build.
1)
I'm wondering how much total dihedral to build the wing with. While I want the plane to still be a fun and stable kind of a weekend flier (or why build a Kadet?), I'd also like to be able to do modest aerobatics and get the plane to at least roll easy and do other simple stuff without losing it's "kadet" charachtersistics. So how much dihedral would be a good compromise? (To avoid confusion if you tell me 6° dihedral, I'll take that to mean 3° for each wing half.)
2)
a) Should I bother putting flaps in a Kadet?
b) If you suggest I add flaps, then should I consider making barndoor style ailerons?...... since I will be losing aileron length when flaps are installed.
3) Solid strip ailerons or built-up from out of the wing?
Thus far, I have never built a plane larger then my 85" Big Bingo or an enlarged 89" AstroHog .Both had solid balsa strip ailerons. I made the aileron for the Hog by shaping a solid 24" rectangle of balsa block into the usual triangular aileron stock configuration to blend in with the contour of the rest of the wing. The Big Bingo came with solid aileron stock. My question is whether I should just build my 104"- 110" Kadet wing as if it is a 3 channel plane with no ailerons. As I'm building the wing, I will add the lumber into the aileron section of the wing and build the ailerons into place. This way they are the same contour of the wing, and all I need to do is cut them free of the wing and install hinges. Of course I will put the necesary extra cross pieces beforehand and add other balsa pieces in there to beef it up to resist the aero- dynamic stresses. What I'm describing is very similar to the construction used when doing barndoor style ailerons as seen here; http://www.angelfire.com/indie/aerostuff/kadflap.htm
Any other recommendations or input is appreciated and will be taken into consideration for the build.
Last edited by rustyrivet; 02-09-2015 at 07:05 AM.
02-08-2015, 09:50 PM
#2
1) I would build it flat with no dihedral.
2) No opinion, but a light 104" Kadet with flaps would probably just hover down to a spot landing...
3) I would build the wing with full length ribs then cut the ailerons loose and face the TE and aileron LE from there.
Mark
2) No opinion, but a light 104" Kadet with flaps would probably just hover down to a spot landing...
3) I would build the wing with full length ribs then cut the ailerons loose and face the TE and aileron LE from there.
Mark
02-09-2015, 06:48 AM
#3
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Hi Rusty,
What a great project you are about to tackle. I built an oversize Kadet last spring, and have been having a ball flying it this year. Mine has a 90" span and only weighs 7.5 lbs.
Since I usually fly mostly oversize, overpowered rockets, it was just time to build a slow flyer. It is nice having a plane you can hand the transmitter over to friends - and then grab it back before they manage to crash it. I did not do a whole build thread on the Kadet, just a simple page on my blog with more photos. You can spend hours flying touch-and-goes with the Kadet and never get tired. I highly recommend it.
After the Kadet I built another oversize trainer, a 102" version of an RCM Trainer 60 from back in the early 80s, and that one I did do a whole build thread. The construction is identical to the Kadet. The larger plane has a symmetrical airfoil so it is a bit more aerobatic, and exciting to fly.
To answer some of your questions, I build the ailerons into the wing, then cut them out. That was shown in another build thread.
I added a bit of dihedral to the wing, as flat wings look like they are drooping. For flaps, I use the radio to use air brakes, flip one switch and both ailerons come down 30degrees. Brings landings down to a walk. I would not build the plane without ailerons. Large light aircraft need all the control input they can get. Flying rudder only would not be able to have enough control for some circumstances when landing in a cross wind, or getting hit with gusts of wind.
Sorry to run you all over the web, but that is where the photos are that might help you with your project. I have blown up dozens of favorite smaller airplanes. To me they just fly better. I even wrote a book about it some years ago. Google 'The Sunday Flyer' for many more photos.
Looking forward to reading about your project!
Tom
What a great project you are about to tackle. I built an oversize Kadet last spring, and have been having a ball flying it this year. Mine has a 90" span and only weighs 7.5 lbs.
Since I usually fly mostly oversize, overpowered rockets, it was just time to build a slow flyer. It is nice having a plane you can hand the transmitter over to friends - and then grab it back before they manage to crash it. I did not do a whole build thread on the Kadet, just a simple page on my blog with more photos. You can spend hours flying touch-and-goes with the Kadet and never get tired. I highly recommend it.
After the Kadet I built another oversize trainer, a 102" version of an RCM Trainer 60 from back in the early 80s, and that one I did do a whole build thread. The construction is identical to the Kadet. The larger plane has a symmetrical airfoil so it is a bit more aerobatic, and exciting to fly.
To answer some of your questions, I build the ailerons into the wing, then cut them out. That was shown in another build thread.
I added a bit of dihedral to the wing, as flat wings look like they are drooping. For flaps, I use the radio to use air brakes, flip one switch and both ailerons come down 30degrees. Brings landings down to a walk. I would not build the plane without ailerons. Large light aircraft need all the control input they can get. Flying rudder only would not be able to have enough control for some circumstances when landing in a cross wind, or getting hit with gusts of wind.
Sorry to run you all over the web, but that is where the photos are that might help you with your project. I have blown up dozens of favorite smaller airplanes. To me they just fly better. I even wrote a book about it some years ago. Google 'The Sunday Flyer' for many more photos.
Looking forward to reading about your project!
Tom
Last edited by tomclark; 02-10-2015 at 07:11 AM.
02-23-2015, 08:37 AM
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Greatl Idea rusty rivet! I modified my Kadet Senior with 1/2 the kit's dihedral (what it is i can't remember). I also have flaps AND spoilers, similar to thesehttp://www.hobbyking.com/hobbyking/store/__28455__Glider_Spoiler_Servoless_Left_and_Right_P air.html
The flaps do help to slow down for landing, because this is not the same floaty Kadet like the trainer, with all the added weight. (but it still fly's slow and floats, don't get me wrong!) With both flaps and spoilers out, i can make near vertical decents without gaining much speed, blurp some power as I round out, and if you time it all just right it makes for a SUPER short landing (length or two of itself) from the near vertical decent. If you time it wrong.......well it makes for a good laugh from anyone watching!!
Have fun!!!
The flaps do help to slow down for landing, because this is not the same floaty Kadet like the trainer, with all the added weight. (but it still fly's slow and floats, don't get me wrong!) With both flaps and spoilers out, i can make near vertical decents without gaining much speed, blurp some power as I round out, and if you time it all just right it makes for a SUPER short landing (length or two of itself) from the near vertical decent. If you time it wrong.......well it makes for a good laugh from anyone watching!!
Have fun!!!
02-24-2015, 11:57 AM
#5
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I did the same, an oversize one powered with a Quadra35cc. I built the wing flat and it worked out very well, still very tame but would do decent rolls and mild aerobatics.
02-27-2015, 04:51 PM
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With ailerons you certainly don't NEED dihedral. But as mentioned above often wings with no dihedral at all look like they are drooping. So I'd stick in a couple of degrees just for giggles.
The ONLY good way to do flaps and ailerons on the one wing is to make "barn door" style conventional surfaces. Otherwise both flaps and ailerons suffer and don't work as well as you will desire.
I'd look at making the trailing edge for the hinges of the flaps and ailerons be set at 80 to 85% of the chord. That'll give you nice wide surfaces that fits in with your desire to stunt it a bit.
The wing loading you're suggesting will come out fairly light if you can manage to build down to the target weight. So flaps aren't really needed to slow down and avoid tip stalling like on a heavy model. But with that light a model you may find that it simply does not want to come down well. So flaps gives you enough drag to dive it slightly down to a touch down and the speed won't rise too much.
And with 15 to 20 degrees the short takeoffs will make the effort MORE than worthwhile...
The ONLY good way to do flaps and ailerons on the one wing is to make "barn door" style conventional surfaces. Otherwise both flaps and ailerons suffer and don't work as well as you will desire.
I'd look at making the trailing edge for the hinges of the flaps and ailerons be set at 80 to 85% of the chord. That'll give you nice wide surfaces that fits in with your desire to stunt it a bit.
The wing loading you're suggesting will come out fairly light if you can manage to build down to the target weight. So flaps aren't really needed to slow down and avoid tip stalling like on a heavy model. But with that light a model you may find that it simply does not want to come down well. So flaps gives you enough drag to dive it slightly down to a touch down and the speed won't rise too much.
And with 15 to 20 degrees the short takeoffs will make the effort MORE than worthwhile...
