NEW VERSION OF SU-27 FLANKER

This is a 24" version. I am still using the material from Staples. However, this time I decided to strip the cardboard from the Depron that lies in between the two layers of cardboard.

I did not take pictures of the procedure. It is very easy. Go to the backyard, get the cardboard wet and peel it. Use you garden hose in "Flat" power mode and scrape the remaining cardboard from the foam.  You will end up with a 30" x 20" x 3/16" (5 millimeters) beautiful piece of fanfold or Depron. The weight is just 70 grams (two ounces). Real good!

FOR THE PLANE DESIGN

I followed the tread at http://www.rcgroups.com/forums/showthread.php?t=336697

Those guys are clever and give you the whole thing.

Here are the plans: su-27 stringfly.pdf

Here are the instructions: readme.txt

Here are some of their photos:

Here are my photos:

Bamboo rod

I used a bamboo stick to strengthen the wings. Its weight: 15 grams. The hobby Store did not have Carbon rods at my needed diameter. Bamboo is lighter and as strong as carbon. The only problem is to find a straight rod in the desired diameter. (I found the bamboo at the Cannery Store in Merced for $1.98 and 24 rods)

400 @ 90 grams (a bit heavy). 6 x 3.5

Both surfaces (wing and stab) work as a Delta. Regard them both as stabilizators and ailerons. There is no "wing" per se. It is a very big stabilizator with aileron functions.  (see video: su27.wmv )

I used two Dubros and two short rods instead of a long one and a short one.

AAA battery pack made from Energisers I bought at Walmart(r)

I used two Dubros(r) and two short rods instead of a long one and a short one.

I know... It's a Russian, but I like the US Flag better.

Specs:

Weight Distribution: (1 oz = 28.35 grams)

Wing Load, weight and trust

Wing load is not bad. 19 grams per dm² makes it a light plane. The recommended specs by the designer are: 9 oz weight, and 5.7 oz trust. I have 12 oz weight and 15.2 oz trust (I could weight 10 oz with a LiPo). Case given, I figure I need at least 9 oz trust (255 grams) at my current weight.

Battery

I might need to get a real battery, a LiPo. My current battery is 100 grams (3.5 oz). Too heavy, and too weak. A LiPo is less than half the weight. I would be weighting 290 grams and at 7.2 V delivering 318 grams of trust at 280 grams of weight.

Engine Specs

Specs for the engine are here: http://www.gws.com.tw/english/product/powersystem/edp400.htm  According to this data, I should get 430 grams of trust with a 6 x 3 @ 9.6V. I have a 6 x 3.5, which is greater in trust delivery. Even @ 7.2V I should get 318 grams of trust according to specs. We will see...

Engine tweaking

I might need to time my engine if I cannot get the juice out of it:  http://www.rcgroups.com/forums/showthread.php?s=&threadid=97414

July 31. Plane flew and landed successfully

First flight

The first fly was with 8 AAA 800mAh batteries and 200 g. thrust. The plane was a bit heavy, but if flew. I could notice than on sharp turns the plane lost some speed and lift. If flies great in straight and level path. Turns had to be wide in order not to loose speed. A 25 yard radius turn is OK. You will not loose altitude at that rate. The plane flies similar to the one on the Ikarus Video (although a bit heavier). http://www.hobby-lobby.com/shockflyer-su27.htm

Second Flight

I decided to try another battery. I had 8 AA 1000mAh. The trust with that battery is 250~275 grams. You also have to add 80 more grams to the weight of the plane. Total weight was 420 grams. The plane was definitely faster. I climbed to 50 feet in a couple of seconds. However, I noticed the same problem on turns. This time the plane lost speed and lift much faster on tight turns. Turns had to be ultra wide. I flew at Joe Herb park.

In white, the intended approach
 

I used the runway in the middle of the screen. I flew in the area on the left. As I was bringing the plane for landing (winds are northwest) on the leg parallel and south of the runway; I was coming in fast. I banked to my left and the plane started to come down as a brick. I tried to widen the turn to gain altitude. I was not going to make it. I was impossible to make a 180 degree turn to final. The plane was heading north and a couple of feet off the ground. I still needed to bank more to the left to head North West to the runway. The plane was really heavy. At full throttle and banking slightly to the left, I wasn't gaining altitude and, I was heading towards the trees north of the planes position. The runway was at 9 O'clock still. I decided to kill the throttle and let the bird down. The landing was smooth. The plane landed gently. I decided not to try it again in this very small park. This combo (420 g. of weight and 250 g. of thrust)  might be good for fast straight flies, with very wide turns. When I say wide I mean 50 or 75 yard radius for the turns in order to maintain altitude. TOO HEAVY!

NOTE: THE PLANE DID NOT NEED FOR ME TO PULL ON THE ELEVATOR WITH THE HEAVY BATTERY. THIS MIGHT MEAN THAT ON THE FIRST FLIGHT I WAS TOO HEAVY ON THE NOSE. I AM MOVING THE C.G. BACK AN INCH.

BACK TO THE DRAWING BOARD

New affordable combo

280 ENGINE

5A ESC

READY TO GO

I am trying a new combo. I do not have fancy brushless motors nor LiPo's. This combo might give me what I want. I light maneuverable plane. The engine is going to be a 280 with a EP5043 6 x 3.5 (5 x 4.3 is no good at my current and low RPM's). The battery is still the 8 AAA 800mAh pack. The speed control is a Great Planes 5A. The Specs are as follows:

Specs:

Weight Distribution: (1 oz = 28.35 grams)

Test Results:

To be added when I fly the plane.

The Center of Gravity has been moved to the back one inch. That is, 20" from the nose. I achieved this by putting the battery a bit behind.

 If flew at the RC field. It does not have enough battery nor power. I made a couple of rounds around the field at 10 or 15' of height. Plane is very stable. It responds very well. It is very easy to fly. My battery/motor did not deliver enough trust. It barely flew. I am trying a different combo, and a different wingspan (larger). The power to weight ratio might be much better for my 400 motor and my 240 g. battery which deliver 300 g of trust with a 6x4 prop. I am going to a Meter wingspan. Click Here

New Ideal Combo

When I can afford it, I will get this motor www.balsapr.com/  with a EP-6030 on direct drive ($50 - 600 g. of thrust! 40 g. of weight). I will also get a nice electronic speed control for brushless ($40 - 21 g.) www.balsapr.com and this LiPo ($40 - 54 g.)  www2.towerhobbies.com. A Charger ($25) www2.towerhobbies.com/  This would be the ideal combo (600 g of thrust @ $155 ) . I would be 26 g lighter and with 600 g of thrust instead of just 125 g.  ROARRRRRRR

- SURF -

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