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Old Mar 05, 2011, 12:57 PM
Falling with style!
Rick Ludtke's Avatar
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46" Pitts Special S1-S

I've been looking for a nice sized scale looking S-1S park flyer for some time now. With the exception of the Banana Hobbies S-2B ARF, there just doesn't seem to be anything out on the market, in any form. Not wanting to give Banana Hobbies any more of my money, and because I would rather have an S-1S like the real one I once flew competition with, I decided to build it from scratch.

Actually, I commissioned my father to build it, as he is retired and has more spare time than I do, and likes to stay busy building models. The Pitts is currently under construction, so I have posted photos of the build progress to date. I will add to the pictures as they become available.

Both my father and I have a lot of experience building full scale sport and antique airplanes, so we have a natural eye for accuracy, and expect our models to appear authenticly scale and correct. But we are more interested in sport flyers than those magnificent intrinsically scale detailed airplanes that grace RC Groups. There are few S-1S designs on the market, and I haven't found any that truly look right to me. This project was inspired primarily by Mike Tully's Pitts S-1S build, who, in my opinion, very accurately captured the true essence of the Pitts S-1S: http://www.rcgroups.com/forums/showthread.php?t=642548

The tail feathers and wing tip bows are all built up from balsa strips laminated around forms.

The tail will receive a fish-line brace wires for added rigidity, and scale appearance. The wings will probably not receive brace wires, as the one piece lower wing shouldn't require it. This will make disassembling the wings much easier.

The plan for the cowling is to wet out one or two layers of lightweight fiberglass on a flat sheet of aluminum, then trim to match the upper and lower cowling patterns. After finish and paint, these panels will then flat wrap the structure, and be held in place with screws. This will allow great access to the battery and electronics, and avoid the need to create molds. The original airplane used flat wrapped aluminum sheet, so this method should appear very authentic.

<<EDIT>> Ultimately we used clear plastic viewfoil sheet material cut out to the shapes of the flat wrap pattern for the cowlings, and simply covered them with film. Durable, light weight, and simple. <<EDIT>>

The canopy in the pictures is trimmed down from the Great Planes Skybolt canopy. This was a left-over from another project. It is cracked, so we used it as a proof-of-concept. It should work nicely, so I need to order a new one for the final part.

I am really looking forward to flying this bird, although my skills are probably only just up to this airplanes speed. This will be my largest scale model yet.

Cheers,

Rick
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Old Mar 07, 2011, 08:00 AM
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Methuen, MA
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Can't wait to see more on this project Rick!

P.S. Maybe you can get a moderator to move this into the scale forum.
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Old Mar 09, 2011, 08:51 PM
Falling with style!
Rick Ludtke's Avatar
USA, WA, Freeland
Joined Nov 2010
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Update: The structure is getting close to cover time. The I-Strut details are complete. The wing leading edges are skinned, and so is the fuselage.

I decided on Ultracote ParkLite for covering material. The plan is Red base, white sunburst trim, and black pinstripe outline; the traditional Pitts scheme. This is our first experience with Parklite, but my reading on materials suggest that it may be the most advanced of the films out there. I like the multi-temp aspect. We'll see.

The structure with servos, reciever, ESC, and motor now weighs 45 ounces. With cover, wheels, wheel pants, cowlings, canopy, etc yet to go, my Dad's original estimate of a 55 ounce flying weight is beginning to sound about right.

Covering materials, 3" wheels, fiberglass cloth, and assorted hardware on order.

Cheers,

Rick
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Old Mar 10, 2011, 09:34 AM
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This is looking great Rick! What did you decide on for a power system?
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Old Mar 10, 2011, 09:45 AM
Falling with style!
Rick Ludtke's Avatar
USA, WA, Freeland
Joined Nov 2010
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Hi Mike,

My Dad and I disagree, he wants to use equipment on hand rather than purchase new. My compromise position is that we'll try out the power system we have left over from the MX-2 wreckage, and then retrofit something else if this proves unsatisfactory.

So, the First Flight configuration will be powered with the SHENG TENG ELECTRIC R/C MODEL PLANE CO.,LTD MX-2 airplane power system:
Motor: 1000 KV, 330 watts
ESC: 30amp
Lipo battery: 3S, 1800mah 15C (11.1V)
Propeller: 13X4 inch

Cheers,

Rick
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Old Mar 11, 2011, 07:02 AM
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Hi Rick,

Try to get some performance benchmarks from ground testing that power system first. It should be sufficient, but limited (kind of like 0-235 power in the real thing). There is no way a 1800mah battery should be used in an application like this, unless it is in parallel with another 1800mah battery. It is the weak link in this system. Get a 2200 mah 20C battery minimum. If you anticipate upgrading the motor, then look for batteries in the 3000mah range. I suspect you are going to need extra mass forward anyway.

P.S. Spend an extra $20 for an external BEC. You don't want to leave this plane at risk from the cheapo ESC from the MX-2
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Old Mar 11, 2011, 08:38 PM
Falling with style!
Rick Ludtke's Avatar
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I will Mike. I gotta admit that I am uncomfortable with our plan.

I started researching alternative power systems, and this is what I am leaning toward:

3548-09 Specifications:
Weight = 5.8 ounces (165 grams)
Diameter = 1.4 inch (35 mm)
Motor length = 1.9 inch (48 mm)
Shaft = 4 mm x 0.7 inch (18 mm)
Voltage = 7.2 - 17.0 (2, 3, or 4 cell Lipo)
Current = 40 amps or 550 watts maximum for 60 seconds
KV = 900
3-cell Lipo Data: The following data was obtained using a Power Up 11.1v 4400 mah 15C (66 amp) Lipo battery:
APC 13 x 6.5E: 70 oz thrust @ 36 amps
TP 13 x 4E: 66 oz thrust @ 32 amps
APC 13 x 8E: 64 oz thrust @ 37 amps
TP 12 x 6E: 60 oz thrust @ 30 amps
Master Airscrew 12 x 6 x 3: 61 oz thrust @ 31 amps with a pitch speed of 48 mph (3 blade prop).
APC 12 x 8E: 56 oz thrust @ 31 amps with a pitch speed of 54 mph
TP 11 x 5.5E: 50 oz thrust @ 24 amps with a pitch speed of 44 mph.
APC 11 x 7E: 52 oz thrust @ 27 amps with a pitch speed of 53 mph.
PRICE: $29.95
http://www.headsuprc.com/servlet/the...lectric/Detail

11.1 volt 3300 mah 35C Lipo Specifications:
Dimensions: 5.3 x 1.7 x 0.8 inches
Weight: 8.9 ounces (252 grams)
Output: 115 amps continuous, 165 amp burst
Charge rate: Up to 3C (9.9 amps) amps. We recommend a fast charge rate of 2C (6.6 amps), and a normal charge rate of 1C (3.3 amps) for longest battery life.
Connectors: A T-Plug connector is installed. The balance connector is the JST XH series 4 pin with 2.5mm pin spacing.
PRICE: $39.95
http://www.headsuprc.com/servlet/the...-35C-EZ/Detail

APC 13 x 6.5E Composite Propellers
Two Each
PRICE: $9.80
http://www.headsuprc.com/servlet/the...-x-6.5E/Detail

50 Amp EZ Flite ESC Specifications:
Weight: 1.9 ounce
Dimensions: 2.2 x 1.3 x .4 inches
Battery: 2, 3 or 4 cell Lipo,
Current: 50 amp (60 amp burst)
BEC: Linear mode, 3 amp, 5 volt (2 cell Lipo = up to 5 micro servos) (3 cell Lipo = up to 4 micro servos) (4 cell Lipo = up to 2 micro servos)
Connectors: A male T-plug connector is installed for the battery connection, and 3.5mm female bullet connectors are installed for the motor connection. Male bullet connectors are included for a motor.
PRICE: $21.95
http://www.headsuprc.com/servlet/the...ite--50/Detail

Thoughts?

Cheers,

Rick
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Old Mar 12, 2011, 11:58 AM
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Methuen, MA
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Looks like a power system that should do the job. I still would spend the extra $20 for an external BEC. That or buy a Castle Creations ESC.

It says that the EZ Flite ESC is rated for 4 micro servos on 3 cells, but you will be needing bigger servos for elevator and rudder.
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Old Mar 13, 2011, 12:21 AM
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United States, PA, Grove City
Joined Jan 2011
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Quote:
Originally Posted by Rick Ludtke View Post
I've been watching and looking for a nice sized scale looking S-1S park flyer for some time now. With the exception of the Banana Hobbies S-2B ARF, there just doesn't seem to be anything out on the market, in any form. Not wanting to give Banana Hobbies any more of my money, and because I would rather have an S-1S like the real one I once flew competition with, I decided to build it from scratch.
......

Cheers,

Rick
If you can build like that, then I don't know why you ever gave them any of your money. Keep up the excellent scratch building!
Bill
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Old Mar 13, 2011, 02:00 PM
Falling with style!
Rick Ludtke's Avatar
USA, WA, Freeland
Joined Nov 2010
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Quote:
Originally Posted by Onna Vakkation View Post
If you can build like that, then I don't know why you ever gave them any of your money. Keep up the excellent scratch building!
Bill
Thanks Bill, but I can't take any credit. Your looking at my fathers handiwork. He never ceases to amaze me.

Cheers,

Rick
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Old Mar 13, 2011, 05:52 PM
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Rick,

At 55 ounces or nearly 3.5 pounds, you will need at least 350 watts for mild sport aerobatics. I'm liking the bigger power systems, and not just because underpowered airplanes are against my religion or something.

The workmanship is very good. I look forward to seeing more!
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Old Mar 13, 2011, 05:57 PM
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Curious - what is the wingspan?
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Old Mar 13, 2011, 06:36 PM
Falling with style!
Rick Ludtke's Avatar
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It has a 46" wing span Eric, or 4.5:1 scale. It's just a little smaller than 1/4 scale (52" span).

I'm glad you asked about the power system Mike, because it sounds like I would be very disapointed with 330 watts, despite how powerful that motor feels. I'll place an order for the new power system after my next payday.

Rick,
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Old Mar 16, 2011, 10:10 PM
Falling with style!
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Status Update 3/16/11

Wheel pant plug and molds complete, ready to lay up parts.

Cheers,

Rick
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Old Mar 20, 2011, 12:50 PM
Falling with style!
Rick Ludtke's Avatar
USA, WA, Freeland
Joined Nov 2010
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Status Update 3/20/2011

Well, new power system is on order. We decided against using the power system I had laying around.

Here is the Power System description:

3548-09 Outrunner Brushless Electric Motor
Weight = 5.8 ounces
Current = 40 amps or 550 watts maximum for 60 seconds
KV = 900
3-cell Lipo & APC 13 x 6.5E = 70 oz thrust @ 36 amps

11.1v 3300mah 35C EZ Flite Lipo Battery
Dimensions: 5.3 x 1.7 x 0.8 inches
Weight: 8.9 ounces (252 grams)
Output: 115 amps continuous, 165 amp burst

APC 13 x 6.5E Composite Propeller

EZ Flite 50 Amp Brushless Motor ESC

3 Amp Universal Battery Elimination Circuit (UBEC)

The airplane is ready to cover, but the Ultracote Parklite I ordered turned out to be not opaque enough, I plan to return it. Regular Ultracoate is on order.

Wheels, wheel collars, canopy, and fiberglass cloth has all arrived from suppliers.

Wheel pant parts are popping out of the molds.

Rick
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