FlyerInOKC

My Feedback: (6)

Acdii, is right it is a pretty easy build and you do have a choice of clipped or full wingspan. I built the kit gear and then decided to replace it with Robart Cub gear. It looks so much better on the Cub gear and you get some beautiful soft landings with it. Several companies offer Cub gear for this kit I wholeheartedly recommend you consider adding it.

SrTelemaster150

Saito FA-120/150/180 are all the same footprint.

The only difference is the 1mm, 2mm increase in cylinder height & they get 10g lighter W/ea step up in size. 900/890/880g respectively.

acerc

SrT, the SD card was shipped yesterday. Let me know when you get it.

Cub Man

My Feedback: (50)

Guys I have added a Show and tell section to The Cub Den. Now I need you to send me stuff to fill this section. Trying to keep it to scale aircraft only. Thanks also to a couple more donations that have rolled in.
I have a 1/4 scale cub on a Zenoa G38, and one on Zenoa G23. My L-4 is an evolution G26, the G26 has plenty of power to fly a 18 to 19 pound cub. You will not be hanging it on a prop but plenty for scale speed and more.

SrTelemaster150

Will do.

Fly North

Thanks for that Information . I have been flying electric so this kind of info is great and really helps with engine choices.

SrTelemaster150

Here is a handy page that has SAITO SINGLE CYLINDER ENGINE SPECIFICATIONS

Fly North

Thanks I will check that out

Leroy Gardner

Is this really the right place to ask a question and expect that the 200 members would have an answer. I remember the last time. OK, the plane is a 1/4 scale J3 Cub, plans call for 2 deg. down and right thrust on the engine. I read some place that 1 &1/2 down and 3 deg. right provided a scale flight path for this plane. Are the plans right or is there other deg's that work better. Engine will likely be a 30 cc gas, other part of question is, does the prop size have anything to do with it.

Thought I could ask now before I start the build and may ask it again, I'm in a learning mood and any help is good help. I'm ordering the Balsa kit and cowl tomorrow, will post a link when I get started, it's a Super Cub conversion if your intrested.

Thank you in advance,

Leroy

Corsair2013

My Feedback: (2)

I know that a Kit can cost more than an ARF, and as long as she doesn't get on the computer and read these threads I am okay!!!!!!!!!!!!

I have many ARF planes that cost a arm and a leg as I buy it then modify it to make it better or to fix some stupid manufacturing issue. I purchased a Carbon Z Cub and took everything out of it and replaced it with all new components because I had heard about problems and even experienced a servo loss myself. The plane flies great now and I have confidence in it.

Like i said before, you all seem to have most of the answers so if I ask too much just tell me to shut up and go away..............

Keith

bikerbc

Hi Leroy You can buy a pretty nice finished PA 18 cowl from hanger 9 . It is a replacement for their Arf . The Landing Gear is a pretty good deal too and almost as good as the Robart Gear .. I have 2 B.U.S.A. 1/3 Cubs 1 1/4 scale B.U.S.A. Cub And one 1/4 scale Sig Cub I think I like the Sig cub the best . I know I fly it the most . The Big 1/3 Cubs are fun but too much grunting for an old timing man . We just finished our clubs annual ( Fall classic) float fly . It is a week long event . It is Western Canada's largest float fly .We had a great time . The best on the beach trophy went to a a B.U.S.A. Super Cub . I bought a spare cowl for my PA 18 because they are so cheap and I also bought a spare landing gear . If you have a chance to look at their struts it is a great set up and fairly easy to make out of streamline tubing. You can make the little ends on the band saw . Are you going to cover in Stits fabric ? I would skip that myself just because if you have a accident repairs are more involved however the stits looks so cool ..Both of my big Cubs are covered that way . .Gosh I wish you lived closer . I would love to watch this build . You truly are a master builder and I am sure will ,improve the kit . Cubs are my favorite plane . They can teach you a lot about flying ,

JNorton

My Feedback: (2)

I'm not sure I could tell the difference. I'd set the firewall at 0,0 and machine a set of shims. By swapping them out you'd have your answer.
John

John_M_

Leroy, the prop diameter and pitch will increase the torque reaction.

On my 1/4 Sig cub I built the firewall with "1.5" degrees down thrust and "0" degrees right thrust (I always build with "0" right thrust, I can always add it later on if needed) ... the saito 1.30 I originally used, had 1.5 degree right thrust and maybe 0.5 degree down thrust build into the engine mounts... so that gave me a total of 1.5 degrees right thrust, and 2 degrees down thrust... with a 16-6 prop, the cub flew pretty much spot on, with no tendency to pull hard to the left.... it didn't show any sever ballooning as power was applied abruptly... but as with any flat bottom airfoil with built in incidence, as the airspeed increased, so the nose would come up and you would have to re-trim, (or mix a little down elevator with throttle).

I did notice with the above setup for a tendency to slowly "ROLL" to the left at higher throttle settings... I checked for any wing twist warps, and it checked out to be true and straight... so it was clearly induced torque roll; a couple clicks of aileron right trim took care of that, (or mix a little right aileron with throttle).

Rudder trim was pretty good, just a couple clicks of right trim; it was such a small amount that I didn't bother adding any additional right thrust.

The bigger engines with larger, higher pitched props are going to have an exaggerated affect on torque response and trim settings.


John M,

acerc

I went 0,0 with a 26cc gas turning a 18x6 Xoar and have no issues.

Leroy Gardner

Hi Ken it's been a long time, I ordered the FS cowl which is made to convert this BUSA kit J3 to Super Cub and it's a bit bigger than the H9. Wings are longer also so I'm going to have to find some aluminum strut material, I'm not using Spruce which comes with the kit. Also the bottom of this plane is 7" wide where the gear mounts, Robart 1/4 scale gear will be used and the suspension tubes may need to be altered to fit right. Covering choice hasn't been made yet, I really like Solartex but I'm going to look at pollyester fabric at the fabric stores and see what my options are. I'm still gathering info. on the real plane and will have a photo session with a real Super Cub shortly, I need pictures of every detail. kit will ship tomorrow.

Good to hear ftom you Ken, when I get started I'll post a link, would like to have you along.

Take care, Leroy

Leroy Gardner

John thanks for that tidbit, I don't fully understand why some need off set while others don't. My recent 1/4 scale Spacewalker never had any 0-0

Leroy

Leroy Gardner

And you Robert probably know as much about this stuff as anyone, could be that over powering this bird may not be the best idea as well as the right prop and pitch making a big difference.

I did visit the Hanger 9 struts and gear stuff, they never said what the struts are made of, sounds like they fold ? Turns out the H-9 super cub is the same size as the BUSA, anyone building this use those parts.?

Leroy

John_M_

Well I can see the need for down thrust on any flat bottom wing configuration with incidence built-in, but I've never practice the use of right thrust in any of my builds... it just so happened that saito 1.30 had it built into the mount.

I have here a H9 1/4 super cub that has at least 3 degrees, if not more right thrust built into the firewall, and its clearly part of the design, (not a mistake) which I think is a bit overboard, but I'll deal with that when the time comes.

BTW... those H9 struts are aluminum, not soft... they're hardened, but to what spec's I couldn't say... probably just work harden during the forming process... they're airfoil / streamlined with steel pins to anchor the ends... they are quite strong... I put a set on my sig cub.


***EDIT***

And just a heads up, the H9 j3 struts are about 1.5" inches longer than the H9 super cubs struts... I used the H9 J3 struts on the sig cub.


John M,

acerc

Question in regards to the flat bottom, don't most flat bottom winged aircraft have incidence built into the wing therefore offsetting the necessity for the engine?

John_M_

All the flat bottom wing configurations I've seen Ace, all have built in incidence... there's incidence on most wings; full symmetrical without a doubt... the engine down thrust is to offset any ballooning as the airspeed increase, the lift from the combination of the incidence and lift characteristics of a flat bottom wing... all flat bottom airfoils have a tendency to balloon as airspeed increases... I had a sig kadet that I took all the incidence out of... it had great penetration, but flew with the nose slightly high at level flight... partly due to it having 0 incidence.

Thats the way I understand it Ace... I'm sure there's someone here with a better explanation.



John M,

Leroy Gardner

John what do you think of the quality of the H9 1/4 J3 Cubs struts and what did they cost, gear for that cub is $114, not bad if it's as good as Robart's for $150. I don't mind saving $$$ and I'm not up on all that is out there. It's nice to have others experience with come of the hardware and where to get it.

Leroy

John_M_

Both the H9 J3 and SC struts are good quality, the only difference is the J3 struts are a bit longer, same otherwise... they are tough; better than the wood struts I originally had... the only thing I changed was the jury struts, as they were way off scale; 1/2 scale, so I made my own out of some K&S 1/2" streamline tubing, should be 3/8" for 1/4 scale, but the K&S 3/8" is a bit small and thin to work with, with my big hands... the K&S streamline tubing is very soft so I reenforced it by running a smaller piece of brass tube down the inside, it worked out nice.

The struts are close to 1/4 scale; it all depends on how you look at it... if you look at the original full sized struts they are "tear drop" shaped, not true streamline... if you want to recreate those same "tear drop" style struts, then the H9 struts are quite a bit wider... in the real world of cub aftermarket replacement parts, they make available true "streamilne" replacement struts... if you take those RW streamline strut dimensions and scale them down 25%, then the H9 struts are within 1/4 scale... the forward strut being just about 1" wide, and the aft strut being about 3/4" wide... the forward strut is scale, where as the aft strut is somewhere in between 1/4 and 1/3 scale... but they still look great on the model.

I think I paid $89 for the j3 strut kit, and it came with all the mounting hardware... with their super cub, they separated the hardware and struts and sold them separately, if you buy the SC Struts you'll need the hardware pak at an additional $45 bucks.


As for the landing gear, Both the H9 j3 and SC gear sets are decent, the J3 set was $79 bucks at one time... the quality isn't as good as Robart, but its not too bad... one thing to take note of... if you want to go scale, the Robart 1/4 scale gear is off on their fore and aft width... the full sized gear is 21.5" inches between the fore and aft pivot points on the arms (center to center)... 25% of that is 5 3/8"... Robarts is 4 5/8"... Both the hangar 9 gear sets are correct 5 7/16", close enough.... the H9 gear has threaded nuts induction welded to the sides of the tubes to thread long screws through for the bungee cords to wrap around... the nuts are quite small, and appear to be a little on the fragile side, but my inlaws H9 J3 cub gear has held up well.


John M,

Leroy Gardner

John that is alot of well explained information, sounds like the J3 struts are the better choice being a bit longer. As for the gear I expected that some width mods. would be needed because of a wider bottom on the BUSA kit. The days are gone when much more equipment for our planes was more available and just knowing where to get it is a challenge in it's self. I will not even start this build until I get the important parts I need, sometime in October I suspect.

Thanks for your help,

Leroy

acerc

Robart has 1/4 scale Cub gear in two different sizes, 6-1/2" part #690 and 7-3/4" part#690B..
I have installed Robart, H9, and two other no name gear. I would recommend the much more robust Robart, especially if you are one for not having soft landing's.

As for sizing outside of those listed above, the X between the sides is easily separated. Then the length can easily be adjusted with some moderate soldering (or brazing) to yield a perfect fit.

John_M_

Yes the H9 j3 struts fit perfectly on the 1/4 Sig Cub, so I would go with the same on the BalsaUSA cub.


Just to clarify the width issue I mentioned... I wasn't referring to the width, side to side across the bottom of the fuselage... as Ace mentioned Robart makes a set for the BalsaUSA Cub which has a wider fuselage..... I was referring to the width of each landing gear arm at the pivot points... the distance from center to center of the pivots is where the dependency is... robarts is 4 5/8".... 25% scale should be 5 3/8"... other than that, the Robart gear is very nice.

If you're not looking for it to be scale, then you can live with the discrepancy... but that width discrepancy changes the geometry of the strut triangle, because the gear rear pivot, where the strut mount is suppose to go, is now in the wrong location... the width discrepancy doesn't really become an issue if you're adding the landing gear as you build the aircraft... but if you choose to add the landing gear after the aircraft is built, then you'll see, and better understand what I'm talking about... Sig did a pretty good job in positioning all the different mounting locations within the scale locations, so a conflict starts to imerge as you attempt to upgrade to the robart gear... I'm sure the same would occur with the BalsaUSA cub as well... I think you'll be ok as long as you incorporate the gear as you build.



John M,