Cox Radio Control Cub Trainer

[David Hourston]

Hi,

I got a 1979 Cox Radio Control Cub Trainer No. 9900. It’s a one channel foam model with a .020 Pee Wee engine and servo integrated in the Rx board. Basically, this is a free flight model with rudder control.

The history behind this model is, my mom bought me one when I was a kid but it arrived broken and was returned. That left a sour taste that I always wanted to satisfy. Never saw one again, until now. Oh my Lord, what a nice and wonderful feeling when I found it!

The model I got has never been flown or started. The radio control system works fine. I’m looking forward to fly it.

Any information about this model will be appreciated.

Thanks for reading the post and hope you enjoyed it!

David

[Ken Culbertson]

Hi,

I got a 1979 Cox Radio Control Cub Trainer No. 9900. It’s a one channel foam model with a .020 Pee Wee engine and servo integrated in the Rx board. Basically, this is a free flight model with rudder control.

The history behind this model is, my mom bought me one when I was a kid but it arrived broken and was returned. That left a sour taste that I always wanted to satisfy. Never saw one again, until now. Oh my Lord, what a nice and wonderful feeling when I found it!

The model I got has never been flown or started. The radio control system works fine. I’m looking forward to fly it.

Any information about this model will be appreciated.

Thanks for reading the post and hope you enjoyed it!

David

Is the radio on a legal frequency?

Ken

[Dan McEntee]

  What you have there is pretty rare. You have managed to find two in your life and most of us the actively search out and collect this stuff have never seen any! If you really think you want to fly  it, learn to fly first on one of the more common trainers that are out there and get competent at it. Then if you still want to fly the Cox model, your chances of keeping it in good shape are better. Once that one is gone, you will probably never see another!
  Type at you later,
   Dan McEntee

[Larry Renger]

They fly well, but be sure to have a big field. They make big turns.

[David Hourston]

  What you have there is pretty rare. You have managed to find two in your life and most of us the actively search out and collect this stuff have never seen any! If you really think you want to fly  it, learn to fly first on one of the more common trainers that are out there and get competent at it. Then if you still want to fly the Cox model, your chances of keeping it in good shape are better. Once that one is gone, you will probably never see another!
  Type at you later,
   Dan McEntee

Dan,

Thanks for your comments and for pointing out those important aspects.

I fly RC airplanes and helis, and have experience with Cox engines.

I’m new to FF. I’m reading to learn about its basics. One important tweak of FF is to test glide the plane looking for shallow glide in a high grass and small slope,  with little or no wind. In addition, the model should be fueled for a short flight in the first attempts.

I’m open to recommendations and tips as well.

[David Hourston]

They fly well, but be sure to have a big field. They make big turns.

Hi Larry,

Thanks for the information. I’ll keep that in mind.

The horizontal stabilizer is mounted using a rubber band but the fuselage lacks the hook that holds the rubber band. The model fuselage doesn’t have any mark this part was ever installed. Moreover, I’ve found pictures of the model and none of them have the part installed. Did Cox want to have it glued instead of using the rubber band?

Thanks.

[John Rist]

The horizontal stabilizer is mounted using a rubber band but the fuselage lacks the hook that holds the rubber band. The model fuselage doesn’t have any mark this part was ever installed. Moreover, I’ve found pictures of the model and none of them have the part installed. Did Cox want to have it glued instead of using the rubber band?

Thanks.

It's pretty common for the wings to be held on with rubber bands looped over the wing dowels.  Are  there holes in the fuselage to allow you to insert the wing dowels? looking at the picture of the fuselage in the instruction sheet it looks like the holes are there.

[David Hourston]

It's pretty common for the wings to be held on with rubber bands looped over the wing dowels.  Are  there holes in the fuselage to allow you to insert the wing dowels? looking at the picture of the fuselage in the instruction sheet it looks like the holes are there.

Yes, the main wing is held by rubber bands and the fuselage has the dowels. The horizontal stabilizer is also held by a rubber band, but the hook that holds the rubber band in place is missing. And I haven’t seen this part installed in the planes photos I have found in the internet.

[David Hourston]

This video was provided by member Kim of the coxengineforum. The model owner added elevator and throttle control. The model flies pretty good, as pointed out by Larry.

[David Hourston]

Is the radio on a legal frequency?

Ken

The radio frequency is 49.890MHz.

[John Rist]

Yes, the main wing is held by rubber bands and the fuselage has the dowels. The horizontal stabilizer is also held by a rubber band, but the hook that holds the rubber band in place is missing. And I haven’t seen this part installed in the planes photos I have found in the internet.

Are you talking about the hook that holds the elevator rubber band?  If you have the part epoxy works well on foam and plastic.

[David Hourston]

Are you talking about the hook that holds the elevator rubber band?  If you have the part epoxy works well on foam and plastic.

Yes, the rubber band hook. I don’t have the hook but will install a skid that will serve as the hook as well.

The model in the video posted above has its horizontal stabilizer glued to the fuselage instead. It might be a good thing to do.

[John Rist]

The radio frequency is 49.890MHz.

I found this:
49 MHz R/C transmitters usually use 49.830 MHz, 49.860 MHz or 49.890 MHz. As noted earlier, frequencies may vary +/- several kHz. Baby monitors are usually found on 49.83 MHz, 49.86 MHz or 49.89 MHz. It's common for a set of R/C toys to be sold with one toy using a 49 MHz RC frequency and the other using a 26 MHz or 27 MHz RC frequency.

The 49.82 MHz to 49.90 MHz band allows for personal hobby transmitters up to 100mw output with any modulation as long as the modulation stays within the 49.82-49.9 MHz band. This provision within Part 15 opens up opportunities for 49 MHz beacons, provided an effective antenna is used.

Looks like it is legal but other users may interfere.  All these other users should be low power and probably won't interfere.  As a small airplane it should stay close to the transmitter and be OK.  Looks like a fun project.  Good luck.

[David Hourston]

Thanks John.

I’ll update the thread as the project progresses.

[John Rist]

Per the video above the owner added throttle and elevator control.  I know this would defeat the child dream of flying it out of the box.  But if it were me I would add elevator control.  Not necessarily throttle. A .020 Cox would be a little bit of a challenge to convert.  However Hobby King has radios for under $50 and very small servos for under $10

https://hobbyking.com/en_us/turnigy-t6a-v2-afhds-mode-2-2-4ghz-6ch-transmitter-w-receiver.html?wrh_pdp=2

https://hobbyking.com/en_us/h-king-hk-282as-ultra-micro-digital-servo-0-11kg-0-08sec-2-2g.html?queryID=544443808203fc77a402b866887e1f5d&objectID=86409&indexName=hbk_live_products_analytics

Might be an issue of the plug on the servo fitting the receiver.  the point is  cheep radios and small servos are rudely available.   

[Tim Wescott]

Per the video above the owner added throttle and elevator control.  I know this would defeat the child dream of flying it out of the box.  But if it were me I would add elevator control.  Not necessarily throttle. A .020 Cox would be a little bit of a challenge to convert.  However Hobby King has radios for under $50 and very small servos for under $10

https://hobbyking.com/en_us/turnigy-t6a-v2-afhds-mode-2-2-4ghz-6ch-transmitter-w-receiver.html?wrh_pdp=2

https://hobbyking.com/en_us/h-king-hk-282as-ultra-micro-digital-servo-0-11kg-0-08sec-2-2g.html?queryID=544443808203fc77a402b866887e1f5d&objectID=86409&indexName=hbk_live_products_analytics

Might be an issue of the plug on the servo fitting the receiver.  the point is  cheep radios and small servos are rudely available.   

Everyone has a "what I would do" -- In my case, I own an ACE-R/C single-channel unit that I used to fly with long ago.  Single-channel RC is a considerably different beast than even two-channel, and its own kind of fun.

[David Hourston]

Per the video above the owner added throttle and elevator control.  I know this would defeat the child dream of flying it out of the box.  But if it were me I would add elevator control.  Not necessarily throttle. A .020 Cox would be a little bit of a challenge to convert.  However Hobby King has radios for under $50 and very small servos for under $10

https://hobbyking.com/en_us/turnigy-t6a-v2-afhds-mode-2-2-4ghz-6ch-transmitter-w-receiver.html?wrh_pdp=2

https://hobbyking.com/en_us/h-king-hk-282as-ultra-micro-digital-servo-0-11kg-0-08sec-2-2g.html?queryID=544443808203fc77a402b866887e1f5d&objectID=86409&indexName=hbk_live_products_analytics

Might be an issue of the plug on the servo fitting the receiver.  the point is  cheep radios and small servos are rudely available.   

John,

Thanks for the recommendation and links but I really want to fly it out of the box.

[David Hourston]

Everyone has a "what I would do" -- In my case, I own an ACE-R/C single-channel unit that I used to fly with long ago.  Single-channel RC is a considerably different beast than even two-channel, and its own kind of fun.

Tim, flying RO will be enthusiastic!

[Bruce Shipp]

Going thru my dad’s stuff I found a brand new in the box Ace Pulse commander system.  I haven’t tried it yet but would like to build a nice, polyhedral FF type for electric power. He was a ham so it is on 54 mghz.  Interference should not be a problem however I may be in violation of a few FCC regulations for a few minutes when I test fly it. I hope the FCC doesn’t monitor this board.

Standing by for the local frequency police to chime in  (that was a sarcasm, humor, a joke)

[Steve Helmick]

Somebody I have known for many years always flies on some "wildcat" frequencies and ignores the FCC entirely. Unlike the IRS, they're underfunded...and unarmed, by the way.  Steve

[Dan McEntee]

Tim, flying RO will be enthusiastic!

  I also have an ACE pulse proportional radio in my stash of stuff. My brother and I bought it from St. Ann Hobby back on the late 1960's. We just played with the actuator and such to get familiar with it. The magazines back then were filled with neat small single channel designs. Then there was an article in American Aircraft Modeler on how to install this system in one of those 3 foot span foam gliders. Eldon toy company I think was the first ones to put these out and there are variations of these in stores still today. We followed the instructions on installing the system, then found a hill one evening to test it out. I felt like one of the freaking Wright Brothers as I was able to just S turn back and forth along the hill riding the very weak lift being generated by the breeze. We were actually flying a plane by remote control! We kept our operations to these type of conditions. Before we pout the radio in the foam glider, we flew it a lot free flight by towing it up, and it flew well enough that we damn near lost it twice! We didn't want that to happen with the precious radio on board! Years later I was flying sailplanes and was at a contest that ACE sponsored out in Higgensville, MO and git to know Tom Rungey and Paul Holsten pretty well over the years. Paul offered to upgrade this system to a stronger actuator for free, so I took him up on his offer. I haven't used it yet, but have the hopes of doing one of the small R/O models that Howard McEntee published back then. When I was flying sailplanes at a local park, there was a guy that would come by now and then with some of these small R/O model powered with a TeeDee .020 and he could REALLY make them sing. Aerobatics are possible just on rudder only once you get the hang of it. I credit my experience with flying rudder only for saving a few of mine and some other people's airplanes after they had an elevator failure of some kind. It's like Bob Hoover always said, "Fly the airplane as far into the crash as possible!"  I encourage you to fly it rudder only since you have R/C experience. I think you will have a ton of fun with it!!  I think those 49MHz frequencies are what most of the toy R/C airplanes use and I'll bet any made today are probably some sort of 2.4 GHz. If the system works and range checks OK, fly it. But keep in mind what Larry said, find a large field and be prepared for wide turns!
   Type at you later and HAVE FUN!
    Dan McEntee

[David Hourston]

  I credit my experience with flying rudder only for saving a few of mine and some other people's airplanes after they had an elevator failure of some kind. It's like Bob Hoover always said, "Fly the airplane as far into the crash as possible!"  I encourage you to fly it rudder only since you have R/C experience. I think you will have a ton of fun with it!!  I think those 49MHz frequencies are what most of the toy R/C airplanes use and I'll bet any made today are probably some sort of 2.4 GHz. If the system works and range checks OK, fly it. But keep in mind what Larry said, find a large field and be prepared for wide turns!
   Type at you later and HAVE FUN!
    Dan McEntee

Hey Dan,

What a story; interesting!
Thanks for sharing it. I appreciate the tips and your enthusiasm.

[GallopingGhostler]

I flew rudder only extensively in the 1970's and 1980's, with Ace R/C Pulse Commander using both Adam's Baby Twin (for .020) and Stomper (for .049 - .10) Actuators. Rudder only is a real blast, one can do a lot with only one channel.

My first aircraft, the 27" clipped wing R/C Schoolboy sold as a kit by Top Flite was Pee Wee powered. It was a good trainer, probably flew a lot like your RTF Cub. When it sustained enough crash/repair/wear-and-tear, I gave it away and put the Pee Wee in a Top Flite 20" Roaring 20 single channel. It was like a miniature Top Dawg in styling, but a total blast, flew faster and stunt better than the Schoolboy.

If you want to spare wear and tear on your history Cox Cub, you can build something in balsa, and fly the Dickens out of it with that same Pee Wee. If you fly over a tall grassy field, it will buffer the bad landings and crashes. These smaller planes handle the crashes better than the larger birds, because of their lower weight (spell "inertia") contributes to their survivability. Only drawback is that they tend to be more sensitive to wind, and are best enjoyed in windless or low wind days.

Greatest blast was when I built a T/F 39" Schoolmaster and powered it with a 1965 model OS Max .10R/C, controlled by a KRD sequential throttle servo. (The transmitter had a push button. I tapped it to change engine settings.) The servo wheel would rotated from 0 degrees to 90, moving throttle from High to Mid Range. Tap transmitter button, would rotate from 90 degrees to 180, putting engine in Idle. Tap throttle button, would then rotate from 180 back up to 360 (or 0 degrees), moving engine from idle back to full throttle. With engine (then called motor) control was like having elevator. At full throttle, the plane climbed out at a 45% angle skyward. At half throttle, it had a gentle climb like it was powered by a Cox .049 engine. Then at idle, I could glide in, shoot touch and goes if I wanted. I'd climb, then put the plane into a spiral dive with full rudder, after building speed, straighten the plane and it would loop.

Here's a link that explains how to adjust and do rudder only stunts.

https://www.airplanesandrockets.com/resources/you-can-stunt-your-rudder-plane-jul-1957-aircraft-modeler.htm

[David Hourston]

I flew rudder only extensively in the 1970's and 1980's, with Ace R/C Pulse Commander using both Adam's Baby Twin (for .020) and Stomper (for .049 - .10) Actuators. Rudder only is a real blast, one can do a lot with only one channel.

With engine (then called motor) control was like having elevator. At full throttle, the plane climbed out at a 45% angle skyward. At half throttle, it had a gentle climb like it was powered by a Cox .049 engine. Then at idle, I could glide in, shoot touch and goes if I wanted. I'd climb, then put the plane into a spiral dive with full rudder, after building speed, straighten the plane and it would loop.

Here's a link that explains how to adjust and do rudder only stunts.

https://www.airplanesandrockets.com/resources/you-can-stunt-your-rudder-plane-jul-1957-aircraft-modeler.htm

Hi,

Impressing what a RO model can do, and perform the aerobatics with that equipment.

Thanks for the link.

[Tim Wescott]

Hi,

Impressing what a RO model can do, and perform the aerobatics with that equipment.

Thanks for the link.

One of my favorites was to do barrel rolls the length of the field, turn by doing a wingover, then do barrel rolls back.  You need a plane with a pretty hefty power to weight ratio for that to happen.

[GallopingGhostler]

One of my favorites was to do barrel rolls the length of the field, turn by doing a wingover, then do barrel rolls back.  You need a plane with a pretty hefty power to weight ratio for that to happen.

If I lived in an area with summer low winds (we don't have this since we border the west Texas Pandhandle), I'd put like my Enya .19-VI TV in my early 1960's Frank Zaic's Airco 48" (weird swept wing cabin, since wing is canted rearward actual wingspan is 46") kit that shows an OS Pet .099 in the nose. That would really bore holes in the sky. 

I'm already thinking about putting that .19 on my Hobby Shack 46" The Real Thing.

[David Hourston]

One of my favorites was to do barrel rolls the length of the field, turn by doing a wingover, then do barrel rolls back.  You need a plane with a pretty hefty power to weight ratio for that to happen.

That’s tempting Tim!

If I lived in an area with summer low winds (we don't have this since we border the west Texas Pandhandle), I'd put like my Enya .19-VI TV in my early 1960's Frank Zaic's Airco 48" (weird swept wing cabin, since wing is canted rearward actual wingspan is 46") kit that shows an OS Pet .099 in the nose. That would really bore holes in the sky. 

I'm already thinking about putting that .19 on my Hobby Shack 46" The Real Thing.

“Rudder Class” Love that phrase!

[Tim Wescott]

If I lived in an area with summer low winds (we don't have this since we border the west Texas Pandhandle)

Tie a long string to the landing gear, and don't bother with starting the engine.

That’s tempting Tim!

“Rudder Class” Love that phrase!

That Cox plane won't get you there -- but others will.

[GallopingGhostler]

Tie a long string to the landing gear, and don't bother with starting the engine.

Better, replace engine with my one of my Testor McCoy .35 Red Heads, upgrade to 4 oz. tank, put a 3 inch bellcrank with pushrod to moveable elevator, a set of 60 foot cables. Wind problem solved.

[David Hourston]

Hello guys,

I cleaned the Pee Wee engine. The engine has never been fired, but the piston/rod joint has 0.012”(0.3mm) of play. Can I run the engine or must reset the piston/rod joint?

Thanks.

[Dan McEntee]

Hello guys,

I cleaned the Pee Wee engine. The engine has never been fired, but the piston/rod joint has 0.012”(0.3mm) of play. Can I run the engine or must reset the piston/rod joint?

Thanks.

     If you have the tool and know how to do it, you could, but I don't think that is excessive. I would at least run the engine a few times, or if you are ready, fly the model a few times and them re-evaluate it.
   Type at you later,
   Dan McEntee

[Jim Kraft]

I learned to fly single channel in the 60's on a buddies Cox .049 powered Piper Cherokee foamy. Cannot remember who put those out, maybe Sterling. I would have to look through my old Catalogs.

Shortly after that, I built a Midwest Esquire with an Enya 19lV and pulser galloping ghost rudder only. I flew it for several years that way, then added throttle and elevator with my first EK radio.

I have been toying with the idea of building another Esquire and installing one of my great running Ohlsson 23 side port ignition engines. Maybe a winter project.

I have a scaled down Lanzo Bomber to 60" with one of my Ohlsson 23's, and a Playboy Sr. with a Super Cyclone on it now. It sometimes fly's with that or an Ohlsson 60 side port. Both are very relaxed flying. I really enjoy flying that type of plane in my old age. Back will not let me fly control line for more than a few minutes at a time.

[David Hourston]

     If you have the tool and know how to do it, you could, but I don't think that is excessive. I would at least run the engine a few times, or if you are ready, fly the model a few times and them re-evaluate it.
   Type at you later,
   Dan McEntee

Dan,

I’ll do what you say, thanks.

I learned to fly single channel in the 60's on a buddies Cox .049 powered Piper Cherokee foamy. Cannot remember who put those out, maybe Sterling. I would have to look through my old Catalogs.

Shortly after that, I built a Midwest Esquire with an Enya 19lV and pulser galloping ghost rudder only. I flew it for several years that way, then added throttle and elevator with my first EK radio.

I have been toying with the idea of building another Esquire and installing one of my great running Ohlsson 23 side port ignition engines. Maybe a winter project.

I have a scaled down Lanzo Bomber to 60" with one of my Ohlsson 23's, and a Playboy Sr. with a Super Cyclone on it now. It sometimes fly's with that or an Ohlsson 60 side port. Both are very relaxed flying. I really enjoy flying that type of plane in my old age. Back will not let me fly control line for more than a few minutes at a time.

Very nice and interesting. Thanks for sharing.

[David Hourston]

The horizontal stabilizer is mounted using a rubber band but the fuselage lacks the hook that holds the rubber band. The model fuselage doesn’t have any mark this part was ever installed. Moreover, I’ve found pictures of the model and none of them have the part installed. Did Cox want to have it glued instead of using the rubber band?

Thanks.

Hello,

The answer to the question above is yes.

I found pictures of the model where the horizontal stabilizer came glued from the factory, and the tail skid doesn’t have the notch to hold the rubber band used to secure the horizontal stabilizer to the fuselage (the model in the picture has the tail fin broken as was the case with the one I got in 1979!)

I have to decide if I use the rubber band or glue the horizontal stabilizer.

[David Hourston]

I have to decide if I use the rubber band or glue the horizontal stabilizer.

I already installed a Dubro tail skid and modified it to hold the rubber band. I have an unmodified skid in case I decide to glue the horizontal stabilizer.

[David Hourston]

Hi guys,

I finished fixing and restoring the Cox Cub Trainer and it’s ready to fly!
Following a recap of the work done:

-Decals removed, repositioned and their edge sealed with epoxy to prevent peel off.
-Foam filler applied to the fuselage and wing on areas with noticiable slits and marks.
-Fixed the broken rudder horn, and vertical fin glued to the fuselage.
-Main gear re-glued to the fuselage because it was loose.
-Tie wraps ends installed and epoxied to the main gear ends because ends were broken and tires were not hold properly.
-Tail skid added to the fuselage.
-Horizontal stabilizer straightened, glued to the fuselage and reinforced at the center because it was weak due to the creases produced when it was not fixed to the fuselage.
-Wing rubber bands factory protector tape installed.
-CA applied to the dowels to prevent fuel oil soaking.
-CA applied to the engine firewall screws to prevent them from loosening due to the vibrations.
-Rx antenna cleaned, Rx switch and integrated servo pot, Tx switch and pot, cleaned and lubed. Of particular interest, the Cox/Sanwa integrated servo motor uses cooper brushes.
-Engine broken in.

[David Hourston]

More pictures:

[David Hourston]

Pictures:

[David Hourston]

Pictures:

[David Hourston]

Video of radio system working: