Tee Dee Performance Crank

The readers of this topic may have realized that this evolved from a TD crank discussion into a building thread...I hope the plentiful information that the replies from 1/2A Nut, Surfer Kris , Mark Bosen and others carried - whom I again thank for the help - will be appreciated notwithstanding the detour from the original topic.

1/2A Nut wrote:50% CG is very bad need 25% from leading edge. 1.86 degrees is just fine simply adjust your CG and trim your elevator in flight and you will have a tame plane.

Lol yes its of no matter now as results had been carried through with the crank testing.

Yes off leading edge per the last two photo's I posted. Your next flight should be more rewarding!

20-25% from leading edge with tank empty...like its going to be when your landing!

Remember the farther forward the weight the less you'll need and don't worry a small amount is not really going to change anything other then having a plane that flies well. I think Bernie had at one time some heavy hubs Cox used on the AT-6 and a Star Wars plane.
Probably the easiest would be to attach lead to the firewall or add a 1/4" fire wall and bring the whole powerplant out forward?

I am having a new set of AAA batteries soldered in series for 4.8 volts and 800mAh and tucked under the baloon tank in the nose thus the extra weight will not only advance the cg position but also add practical value.

Those are big batteries for 3 micro servos how much does it weigh?

I measured round about 30 grams = 1oz for the 4 altogether...I need about 40 grams to balance the plane, put in the nose...so the AAA battery weight is in the right ballpark

Ok great! Does that make it happen with the lighter 049 with a throttle sleeve?

I just got a digital scale and in fact the battery weighs 52gramms so it should also suffice for the 049 with throttle ring.

I'm still surprised that you need that much weight in the nose, but one cannot compromise with the CG position.
Another option would be to move the wing, but that is not an easy job on a low wing plane.

For the wing incidence you can trim on that later, with the rubber bands you can simply shim the wing at the leading edge and see how that affects the flight. There is no need to carve into the fuselage until you are happy with the flight characteristics.

Just as a comparison, below is an example of one of my planes and the distribution of things in order to get the CG at the right place. As you can see the battery ends up pretty far back in the fuselage with the Cox 05RC in the front. Even with this layout the CG position was very conservative.

Surfer_kris wrote:I'm still surprised that you need that much weight in the nose, but one cannot compromise with the CG position.

Thanks, Kris,

one should not forget that my plane was made based on rough measurements of pics posted on this forum, and the dimensions were not always seen in a right angle so the disproportional tail or nose sections are a consequence of this.

As far as carving the wing saddle is concerned, I have the same idea that I will put termporarily some bands in between the saddle and the wing so as to vary the angle of incidence and only carve the saddle if needed.

The weight I need is easy to calculate: i want to put it in a distance about 10 times the distance between current and the desired CG position, and because the moment by the added wight on the new CG should be the same as the moment of the entire weight of the plane, the ratio is inversely proportional with the distances: thus I need to add 1/10th of the planes weight in a distance of the said 10 times...this is rughly 40 grams

But I am sure you are aware of this.

To be sure you invert the plane when checking the CG correct?
Remember flight test one change at a time.

1/2A Nut wrote:To be sure you invert the plane when checking the CG correct?
Remember flight test one change at a time.

You mean turning it upside down when checking the CG because the plane is a low-winger and the CG is located close to the belly?

Yes sir fast way to confirm static balance at the wings airfoil

I seem to have completed the settings before the next flight planned for Saturday. I ended up with a CG position around 25% off the leading edge. The plane with tank empty weighs 14 ounces.

Thank you all for your continued suppprt. i will post another video on the - hopefully less hectic -flight on Saturday.

So you're up 1oz at 14oz, given the amount of wing area available should this next landing prove stable and you get to enjoy a nice glide in let us know how well it floats in to base camp. Dont forget to fly closer to the pilot so the camera can get some plane action

I re-maidened the SEED (Skortch Eastern European Dragster) today, and can tell you the plane flies super stable and even glides with the engine off very safely.

1/2A Nut, thanks fior the inspiration, the design that I stole from your pics and the numerous advice you gave me. I also thank Kris (I hope I did not offend him with the TD051 rpm discussions), Rusty,Mark for their useful advice, and all other readers who took the hassle of following the building thread of an enthusiastic amateur..

Now it is high time I tried to remove the CA spots from the kitchen platform for an all-around satisfaction including that of my wife...

Fantastic Andras!!!! Any vid???

1/2A Nut wrote:Fantastic Andras!!!!  Any vid???

I was alone in the field today (let alone a bunch of people walking dogs) and tomorrow my wife cannot join me either. The next time I have a co-pilot I will have him/her shoot a video.

It flies straigh and does wingovers equally easily.

I am comtemplating to change out the TD050 with a more powerful, exhasut-throttled TD051.

I have some different cox powered options for the Skorch.
In the pic:
- Galbraith head
- Nelson plug
- Tornado carb with air bleed
- Red anodized aluminum carb body
- Tatone muffler with pressure tap
- Tornado grish 5x4 prop with TD .09 spinner
- Phenolic thrust washer
- Non SPI .051 cylinder

I sourced some finishing supplies online:
I have applied 7 coats of fuel proofing gloss clear coats over the ply fuselage. I first filled in the grains with 2 part Z-poxy finishing resin squeezing off all excess resin off the fuselage so primarily only the grains were filled in then applied the gloss thinner coats using LustreKote by Top Flite. This method allows for a lighter finish without the need of fiberglass and a thick coat of the more heavy epoxy resin. With the drying / curing times involved the whole process took about a week to finish.

I have some other hopped up cox engines and a stock TD 050 RC that will get a pressure tap on the muffler to try for the fun of it but the reality is the modified engine in the pic will provide statically additional
rpm 1.2k to 2k and serve the plane well as it can idle low for stunt flying and with pressure maintaining great fuel delivery at full throttle.  

I like the natural wood finish. Good job Nut!

Thank you Cribbs!

Agreed I just couldn't bare to cover up all that lovely wood grain.

Do you fuel-proof the tank compartment as well just in case leakage occurs? The plywood will absorb castor and get stained.

Yes good point, I fueled proofed the inside just past the landing gear former.

- First with Z-poxy resin pressed into the grains
- After 24hrs wiped clean of residue
- Finished up with 7 thin coats of the LustreKote.

The process seems to have kept the weight down nice glossy hard finish. After the 6th coat I fine sanded everything smooth and applied the last coat.

The Lil Speedy TD .020 version did not get its grains filled with Z-poxy a mistake on my part. The fuselage had 4 coats of the LustreKote yet the sneaky castor oil has stained the front end thru migration or time, lucky for me I have used ply so its still very strong. The inside was clear coated the oil appears only on the outside surface.