Shawn’s Page one of two

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The last five weeks have been more detail oriented. We have finalized all of the shapes except for the horizontal tail plane. Some of the work that I’ve done is as follows.

The role the landing gear plays on this aircraft is as demanding as the airframe (Goals 4 & 7). I used a tailing link style because it must handle the harsh landings encountered during short landings where a high rate of decent helps to reduce the role out distance as shown here; Straight and Squished. The nose gear was the most challenging due to the placement of the engine and camera box leaving a very small stowage space. The nose gear also needs to be long enough to allow the prop to clear the ground. Basically a 6” gear needs to fit in a 3” box. As with most RC aircraft the nose wheel also needs to steer left and right on the ground for taxiing purposes. I developed and used a slider/folding technique to accomplish this. If you internet connection is fast than watch this PowerPoint presentation.

The vertical stabilizers have been finalized and their bottom extensions serve three purposes:

1. They distribute the torsion loading of the tail over a larger area.
2. The shape of the center section is such that airflow could roll off the sides and lose effect so the extensions hold this flow in place (Goals 1,6 & 8).
3. They also provide a small degree of yaw resistance in place of a fuselage.

Thicker airfoils stall later than thinner ones and if the outer portion of a wing stalls first than control will be lost. I have also started development of a center section spoiler that will disrupt the airflow over the top of the center wing when the flaps are in the landing configuration, to be sure that the center will stall first. This should cause the center to stall first and allow for a controlled recovery and also serve to increase the controlled rate of decent to reduce the roll out distance (Goal 7).

The design of the wing is now coming together as it’s internal spaces begin to fill in. This view illustrates Goals 2, 4 & 9.

I have also (with input from Michael, Nick, Eric, and Jeremy) finalized the shape of the aircrafts nose to archive goals 8 & 10. The following sketches illustrate the design progression of this piece, including the need to rotate the engine 180 degrees to achieve a workable shape.

Sketch 1

Sketch 2

Sketch 3

Sketch 4

Final Shape

Jet Wing, or version two perhaps, with the modular cargo bay filled with a ducted fan unit. Hey, you never know.

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We are designing and building a blended wing RC aircraft, or flying wing with a tail. The point of this aircraft is two fold.

First is the construction style was derived to alleviate the problem of warped airframes due to uneven construction surfaces.

The second point is the integration of an exceptionally large modular cargo bay for photographing, paint balling, and anything else that we can think up.

So far I have designed the basic framework for the airframe. I used two different Eppler (E197, and E1230) Airfoils in a box style frame.

The Airfoils were downloaded from the internet and scaled to fit the basic silhouette as needed.

Nick sculpted the skin, Eric designed the box, and Michael modeled the engine.

I then put all the components together and sketched some ideas for a cowling.

Some additional pictures are here.

Wing area calculations

Bad ideas that didn’t “fly”

Some communiqué along the way.

Email 1 Email 5 Email 10

My chart Email 6 Email 11

Email 2 Email 7 Email 12

Email 3 Email 8 Email 13

Email 4 Email 9 Email 14

This is a revised list of goals for this aircraft.

1. Heavy lift light weight airframe.
2. Large volume internal cargo bay.
3. Simple construction.
4. Compact internal design.
5. Small efficient engine (direct contradiction to number 1).
6. Short take off run (direct contradiction to number 5).
7. Short landing on rough terrain (direct contradiction to number 9).
8. Efficient fight for good endurance (direct contradiction to numbers 1 and 2).
9. Retractable light weight landing gear (direct contradiction to numbers 3 and 4).

10. Good looks…well we can try at least (direct contradiction to numbers 1 -7).

Clearly a challenge in design.