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Post  GallopingGhostler Sat Jun 20, 2015 4:25 pm

I would have run the pushrod under, also. There is already a well crafted guide midway to minimize pushrod bowing under compression. Smile

Flight loads on the 1/2-A elevator are already light. Even CL combat and stunt aircraft don't go through extra measures by putting horn on top.

In RC, particularly in say large 3D aircraft, where the larger elevator surfaces are prone to causing the pushrod to bow and possibly fail to provide the proper upward motion, option is to go to a pull-pull type arrangement. Other more common tried and true option was the sheathed nylon pushrod cable. The sheathing prevented bending and distorting of the pushrod. Another was use of a round hardwood dowel or square balsa shaft with wire ends. It had less tendency to bend in compression.

Some of the CL stunt aircraft I've seen use a hardwood dowel for rigidity with reasonable weight.

In the 1/2-A RC aircraft I've flown I've never had problems with pushrods deforming. More likely than not, it was my improper input commands (dumb thumbs) that resulted in crashes than any deformation of pushrods. Shocked
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Post  getback Sat Jun 20, 2015 5:13 pm

Keep it simple what works ..... 1/2A stunt trainer design - Page 7 Push_r10  1/2A stunt trainer design - Page 7 Push_r11  1/2A stunt trainer design - Page 7 Push_r12  Don't use this one  1/2A stunt trainer design - Page 7 Push_r13  WOW and I thought it was ready to fly Huh... lol! lol! Thanks for letting me find that Rolling Eyes just bent the wire the other way for top mount . Eric
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Post  rogermharris Sat Jun 20, 2015 5:42 pm

Oh I'm just having fun with this one.  While I understand straighter is better (less points to flex). I don't expect this one to bee a high performance, high speed plane.
If I see any odd stuff going on while flying it, I will certainly move the horn to the bottom and make a straighter push rod. I don't recall ever seeing a wood dowel used. That sounds cool and could certainly bee more rigid. Anything I build that is more sporty will bee as straight and linear as possible


Thanks again for all the history and info!
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Post  roddie Sun Jun 21, 2015 11:43 am

I just noticed the radius cuts at the rear of the ply nose-doublers. That's a nice touch to add a more dimensional look to a profile fuse too.

My 2nd self-designed flying model was a little 1/2A bipe. I've still got it.. but it's "war ravaged". Shown below with flaps which I added later.. but never flight tested. Probably a good thing.. because those two 1/16" wire pushrods certainly added a lot of weight to the tail. It was part of a mod for a Fox .15 that never happened. Plus.. I don't know whether flaps on a bipe would be better on the top wing or the bottom one.
1/2A stunt trainer design - Page 7 Dsc01910

circa 1992 (pre-flaps) with a Babe Bee fitted. The wings and tail-feathers are direct tracings of a Sterling E2 DR1 kit's top and bottom wing and tailplane. The wing-struts are craft (popsicle) sticks CA'd into slots in the sheet wings. I used a vertical 1/4" balsa center support-block between the upper-wing and fuse.

1/2A stunt trainer design - Page 7 Rog_cu13

opted soon after for a product-engine style with an external wedge-tank.

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I had a lot of fun with this model, and often did "balloon-busts" and towed happy birthday banners with it.

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Installing flaps on only one wing, positions them far from the datum line.. and installing upper and lower flaps requires a degree in mechanical engineering for the linkage!  Shocked This would be an interesting topic for discussion. I'm thinking that the airflow over a bipe's tailplane having "elevator-only" control, would be disrupted when the model pitches toward extremes. The Bi-Slob is an example of both wings having flaps. Check out the engine-offset!

1/2A stunt trainer design - Page 7 Bi-slo10


Last edited by roddie on Sun Jun 21, 2015 11:50 am; edited 1 time in total (Reason for editing : flap considerations for a bipe)
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Post  Ken Cook Sun Jun 21, 2015 12:25 pm

Roddie, having built many Bi-Slobs I can tell you first hand that the engine offset on that plane is totally unnecessary. It makes the plane actually fly poorly. While it's become a standard on this plane including the ridiculous amount of rudder offset, it makes the plane bounce on the end of the lines. A better way to state is if you have a dog on a slack leash and let him run until he hits the end. This causes the plane to snap on the end of the lines. The original Bi-Slob was built using a cardboard fuse. A very integral part that's left out on the Bi-slob is that the bellcrank platform is directly glued to the fuse sides. I've seen many rip the bellcrank through the fuse. Ken
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Post  rogermharris Sun Jun 21, 2015 1:22 pm

Thanks roddie. I figured if I was going to add doubters that they should look nice. I also added them to the stunt trainer and that one has them cut to accent the cockpit area.  
I will post a couple pics later
Roadie what about dual stab/ elevators more in line with the wings???
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Post  rogermharris Sun Jun 21, 2015 3:35 pm

Ok... Back to where this thread started before it got way off base. LOL!

Here is the stunt trainer the thread started with. It's mostly a babee ringmaster but built around a piece of sig's air foil.  The cord was increased from 4" to 4.5" per roddie's suggestion.  I have the flaps at 1to1 with the elevator. The LHS was out of small control horns so I made one up from some light weight aluminum angle. I also used a couple aluminum pop rivets with the mandrel removed for bushings

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Post  roddie Sun Jun 21, 2015 5:02 pm

Geez Rog.. that's super cool! Cool I really like the looks! It looks very capable of stunt to me.

I had very good luck running external wedge-tanks with the Cox .049 horseshoe backplate for the reed-valve engines. It also moves the fuel-weight closer to the c of g. You probably have a bee already, that could be converted. I bought the back-plates and needles direct from Cox.. back in the days that you could, but you can still get them from Cox International.

Below are examples of the horseshoe backplate. The firewall mount pattern is smaller.. but the holes can be drilled along with the tank-mount's pattern.. just inside of it. I use "Perfect" brand wedge tanks on my 1/2A profile models, which worked well with this style backplate.

1/2A stunt trainer design - Page 7 Cef_me10

Have you thought about stitch-hinging the flaps on later builds? I'm gonna try stitching sooner or later.. The more I see it done.. the more I like the way it looks.

Have you thought about any names? It's a handsome design.
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Post  rogermharris Sun Jun 21, 2015 5:20 pm

well maybee i will switch the engine out. i do have a couple of those back plates and i think i have an old tank laying around. at the moment its got this one on it mounted with t-nuts.

i will bee sewing the flaps on the next one. much less hassle than hinges.
i think i'm also going to build one with a but longer fuse to move the tail feathers back some just to see how it acts and what version flies better

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Post  rogermharris Mon Jun 29, 2015 5:43 pm

Great News!

Got my wood order today from Sig!!! It was still not showing shipped on the website and never got notification till I got a "delivered" email today.

Ill bee doing some lunch time lawyer'sin for a few days!!1/2A stunt trainer design - Page 7 28952EE6-9251-4538-8FC2-A9D07F61C914
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Post  duke.johnson Mon Jun 29, 2015 6:42 pm

This is awesome news!!!!!!!!!  Can't wait.
bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce
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Post  rogermharris Mon Jun 29, 2015 7:24 pm

duke.johnson wrote:This is awesome news!!!!!!!!!  Can't wait.
bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce bounce
bounce cheers Beer Cheers Thumbs Up Thumbs Up
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Post  roddie Mon Jun 29, 2015 7:45 pm

rogermharris wrote:Great News!

Got my wood order today from Sig!!! It was still not showing shipped on the website and never got notification till I got a "delivered" email today.

Ill bee doing some lunch time lawyer'sin for a few days!!1/2A stunt trainer design - Page 7 28952EE6-9251-4538-8FC2-A9D07F61C914

That's a nice surprise to come home to. All micro-sanded.. ready to cut. I have a lot of wood.. but most of the sheets are rough-cut and narrow (1.75") so.. making a plank-wing requires edge-gluing at least two pieces together. I made fixtures to sand the sheets to three different common thicknesses.. but.. I need to obtain a 24"L. aluminum extrusion (I-beam) that I can face with coarse/fine abrasive for a block. If it works well... I'll probably sand a lot of stock. The fixture sizes are 1/4", 1/8" and 1/16" and are made from pairs of 36"L. gaged steel strips. One serves as a back-fence and the other is held by hand against the sheet's front edge while block-sanding.

1/2A stunt trainer design - Page 7 11-3-110

I hope all goes well with the laser-cutting. I'm really enjoying this thread Rog. Oh btw.. I'd say that the pit-box you designed/built, is of heirloom quality!
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Post  rogermharris Mon Jun 29, 2015 8:16 pm

I was happy with the way the pit box came out. It went together near perfect on the first attempt. Normally there is an issue somewhere.  The glow plug top came after cutting the handle. One of those hmmmm moments. I will tweak it some if I make anymore. If anyone is interested I will make them in kit from as well.


Roddie. Rather than aluminum I been that would need to be milled to bee perfectly flat, use MDF as your sanding surface?  That stuff is pretty much dead flat. You could stack it into an I beam.

I'm enjoying this thread as well. Looking forward to getting these kits cut and shipped. Then on to a couple other requested projects. Hard to focus with so many projects hanging.
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Post  getback Tue Jun 30, 2015 7:33 am

Roger your about to make a lot of people happy and busy Smile did they ship the ply. or still on back order ?,, trainer is looking really good Airplane eric Beer Cheers ( for later )
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Post  rogermharris Tue Jun 30, 2015 7:56 am

getback wrote:Roger your about to make a lot of people happy and busy Smile  did they ship the ply. or still on back order ?,, trainer is looking really good Airplane  eric  Beer Cheers ( for later )

the 1/16" ply was back ordered so i canceled it and will pick it up locally. it's a couple more dollars but, no shipping. will start cutting today at lunch and come in over the weekend if need bee .. hopefully it goes smoothly. cutting 8 kits.Affraid or WOW! Warm

i had hoped to have the stunt trainer painted by now. it's all sanded and sealed..not enough time in the day or at least time in the day that i feel like doing something LOL!! lol!
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Post  rogermharris Tue Jun 30, 2015 2:11 pm

[img]1/2A stunt trainer design - Page 7 E44C00B8-CC1B-40A0-AB96-E10E7666417B[/img]well i extended lunch time today and got all the balsa cut for 8 kits.
firewalls tomorrow and i will pick up the plywood needed most likely Thursday hopefully finish things up.  then its a matter of packing everything....
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Post  getback Wed Jul 01, 2015 6:30 am

Man you were really moving from the times I talked to you yesterday , Looking GOOD !! Airplane
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Post  duke.johnson Wed Jul 01, 2015 9:50 am

I can't hardly wait! I don't understand the why though. I just told a friend about the little pilot last night. It will be a great addition to my ringmaster fleet, and he first RM bipe.
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Post  duke.johnson Wed Jul 01, 2015 9:51 am

After the Beginner RM bipe, we should talk Roger into cutting a short kit for the Baby RM bipe.
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Post  rogermharris Wed Jul 01, 2015 10:14 am

duke.johnson wrote:After the Beginner RM bipe, we should talk Roger into cutting a short kit for the Baby RM bipe.
might you be referring to the stunt wing version???
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Post  duke.johnson Wed Jul 01, 2015 10:37 am

rogermharris wrote:
duke.johnson wrote:After the Beginner RM bipe, we should talk Roger into cutting a short kit for the Baby RM bipe.
might you be referring to the stunt wing version???
The beginner RM has the slab wing like you're cutting now and the baby RM has a built up wing with ribs. Usually the same size plane.
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Post  rogermharris Wed Jul 01, 2015 10:45 am

duke.johnson wrote:
rogermharris wrote:
duke.johnson wrote:After the Beginner RM bipe, we should talk Roger into cutting a short kit for the Baby RM bipe.
might you be referring to the stunt wing version???
The beginner RM has the slab wing like you're cutting now and the baby RM has a built up wing with ribs.  Usually the same size plane.

no comment... Eyebrows Wink Shh Shh
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Post  duke.johnson Wed Jul 01, 2015 10:50 am

I'm sorry Roger, maybe I missed something. I'm all hoped up on allergy medicine. But hears a links to Pat Kings plans on Stunt Hangar's vendors corner.
http://stunthanger.com/smf/index.php/topic,22652.0.html
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Post  rogermharris Wed Jul 01, 2015 10:58 am

duke.johnson wrote:I'm sorry Roger, maybe I missed something. I'm all hoped up on allergy medicine. But hears a links to Pat Kings plans on Stunt Hangar's vendors corner.
http://stunthanger.com/smf/index.php/topic,22652.0.html


LOL!! not missing anything Duke...

i have already had a request for a BRM Bipe kit (stay tuned).

i have a couple of one off kit requests after this run of bipes and then we will see.

one thing i like to do is cut and assemble a kit before committing to cutting a bunch.
that way i have time to make and adjustments and changes along with seeing what i may have forgotten.
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