Project Bush Demon

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Arkan

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Jun 6, 2021
Messages
79
Greeting From Arkansas. Currently I am using aircraft design as a way to avoid the What if questions while the doctors figure out what is going on with my health. In the past I have designed and built several RC planes, and the concepts are the same. This is the first time I have ever attempted to design a full sized plane. I am sure you can tell from the name, I am working on a back Country Bush plane. I have several thoughts and ideas for STOL performance. I am for the most part a Arm Chair designer, I don't have any engineering in my back ground, so if i ask dumb questions, please forgive me.
 

Arkan

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Joined
Jun 6, 2021
Messages
79
I thought I would go ahead and update what my design goals for my STOL Bush plane.


Project Goals

To design an experimental aircraft with STOL (Short Take Off and Landing) capabilities.
Target take off weight of less than 1500 lbs.

Features

Rotax 915 SI engine
4130 Chrome Molly frame construction
Dual Wing Tanks
Tail dragger configuration
Deployable leading edge slats
forward facing belly cam (just to help see for Obstructions when on taxiway)
50” wide 50” tall cabin
20 foot length
32 foot wingspan

Safety Features

Emergency GPS beacon
Emergency Parachute for the plane

Questions to Answer

Ailerons, or Flaperons
Dihedral? if so How much?
what size of tubing to use in construction for strength.
What type of coverings to use
Wing Spare material
Wing rib material
Can Carbon fiber be used to make Ailerons or leading edge slats?



 

Arkan

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Joined
Jun 6, 2021
Messages
79
I think you guys are missing the point. So I will explain in better detail. I do not have a pilots license, although I want to get mine. I am experiencing health problems, and my Doctor said there is a possibility of Cancer. We don't know for sure and have no idea what is wrong. So I came up with this idea of designing a plane as a form of mental gymnastics. This keeps me from dwelling on the health issues and the unanswered questions.

now any help would be appreciated. I know I have a lot to learn and I spend a lot of time researching, learning, and and drawing out ideas and designs.

I know I could buy or modify a plane cheaper, I honestly do not expect to build this plane, I don't have the money. But designing, finding solutions, figuring out new concepts and mentality applying what I learn and figure out in design keeps my mind busy. Gives me something to do in idle time to keep me from dwelling on what if's and unknowns in relation to my health.
 

Arkan

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Joined
Jun 6, 2021
Messages
79
What planes on the market are close to your needs?
I have no idea.... I guess if I had the money, I would buy some kit plane and modify it to a back country STOL bush plane. I don't have the money though, hell I have never flown in anything smaller than a commercial airliner, and have never even sat in the cockpit of anything. I got into RC planes because I couldn't afford to take pilot lessons. Flying FPV is the closest I have ever been to in control of an aircraft. Honestly it is something I regret. I get these issues figured out with my Health I plan on fixing that mistake and get my pilots license. Though owning a plane is something I don't think I will be able to afford.
 

Voidhawk9

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HBA Supporter
Joined
Mar 26, 2012
Messages
626
Location
Timaru, NZ
HI there, looks like a fun project!
I recommend you get this book, it'll walk you through the basics of aircraft design, probably exactly what you need.

If you like that one and want even more, then get this one, same author, but aimed more at the professional and is far deeper. Even if you can't follow the engineering math, you'll learn a lot - I did.

And watch Mike Patey's videos on the Youtubes, if you haven't already. :cool:
 

Arkan

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Joined
Jun 6, 2021
Messages
79
And watch Mike Patey's videos on the Youtubes, if you haven't already. :cool:
lol.... watch him constantly, He truely is an inspiration. It was his intro that got me to thinking on this. I am going to check out those books, and thank you
 

TFF

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Joined
Apr 28, 2010
Messages
15,345
Location
Memphis, TN
What planes that are similar have nothing to do with if you can afford them or not, it is a starting place on where to design.

The short answer is everything is a copy of a Piper Cub and modified and shifted to fit; that unluckily is too simple an answer.

I suggest tying to find plans of similar airplanes first to study. There are Cub plans, parasol plans like the Pietenpol, version with steel fuselage, and Acey Ducey, the closest think on the market is the Wittman Buttercup. Asking what size tubing when there is at least ten different sizes mixed together on any plane doesn’t work. I have built RC planes since I was pretty young, and the same thing goes, study like plans so at least you know where all the parts go when you design your first one. This with the more technical side will design an ace airplane.
 

Arkan

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Joined
Jun 6, 2021
Messages
79
What planes that are similar have nothing to do with if you can afford them or not, it is a starting place on where to design.

The short answer is everything is a copy of a Piper Cub and modified and shifted to fit; that unluckily is too simple an answer.

I suggest tying to find plans of similar airplanes first to study. There are Cub plans, parasol plans like the Pietenpol, version with steel fuselage, and Acey Ducey, the closest think on the market is the Wittman Buttercup. Asking what size tubing when there is at least ten different sizes mixed together on any plane doesn’t work. I have built RC planes since I was pretty young, and the same thing goes, study like plans so at least you know where all the parts go when you design your first one. This with the more technical side will design an ace airplane.
Okay I now understand you, I have been looking at not only the Piper Cub J3 and PA11 designs, but also at Fissler Storch, These are the current Plans and drawings i have been pouring over, I also understand that many tube sizes are used. I even watch tons of Mike Pateys videos, and to increase wing strength, I am thinking on his application of two wing spares, a forward and rear spare design. (i believe that is what he is doing on Scappy) So as i am in the research aspect of this at the moment. and trying to learn to use the Auto Cad programs I downloaded. (found FreeCad and Libre Cad online for free. and have 3D blender as well) Most of what i am doing now is pouring over the information, and coming up with a Plan of attack on the design. While i try to learn the programs, i do a lot of Graph paper drawing on ideas, and i have a stack of those.

Basicly, I am looking at any and all plans i can get my hands on for not only Ideas but studying them to get design concepts, even in my shop, I have poured over and even dysected some of the wings off my RC's .
 

blane.c

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HBA Supporter
Joined
Jun 27, 2015
Messages
5,002
Location
capital district NY
A few things to consider.

Most here will agree the most common reason for aircraft engine stoppage is fuel starvation. Sometimes there is no gas in the airplane at all that causes this stoppage and sometimes there is plenty of gas in the airplane but none is getting to the engine either way same dire result. While you cannot cure stupid on the one hand making the fuel system as simple as possible helps on the other hand. Fuel availability in the bush varies from extraordinarily expensive, to logistically difficult to get to the airplane, to contaminated/mixed fuels in storage facility, to not available period. It helps to have long range fuel tanks so that you have enough fuel to get to where you are going, do some local flying, and return. Of course you can always bring cans of fuel in the baggage if you have a place to land and put in in the tanks. Straining fuel that goes into the tanks is imperative but it doesn't hurt to have a good fuel filter system that will not starve the engine of fuel (it bypasses obstruction if necessary).

A crash resistant cabin is essential. Many of the Atlee Dodge Super Cub modifications are to reinforce the cub's cabin structure. Cabin greenhouse brace and lightweight diamond plate flooring to name a couple.

When the tail quits flying the airplane quits flying so it doesn't do any good to design a wing that fly's slower than that speed that can be supported by the rest of the plane.

Ailerons lose responsiveness first in slow flight, then the elevators, and finally the rudder. Conversely the rudders are first to be effective. One of the improvements over the Super Cub in more modern aircraft designs is aileron response is improved at lower airspeeds. Sometimes the ailerons in cub type airplanes at slow airspeed the aileron moving down would stall causing that wing to stall or at least the outboard section of it, this was to often at an altitude to low to recover from the events that followed.

You have to be able to hand prop the engine. Seriously some dumb*** is going to leave a switch on and the battery is going to be dead and there you are in the middle of nowhere.

Tailwheels are under appreciated. They are drug through some awful things and no matter how stout do not look new very long in serious bush usage, but a wimpy tailwheel will disappear ... like magic. Tricycle gear aircraft do amazingly well if the pilot has the sense to get the nose wheel off the ground early in the take-off run and put it down as late as possible in the landing.

The main landing gear must be robust and should include adequate tires for inhospitable terrain and excellent brakes.

In bush operations you will have unexpected adverse conditions. Mud will get all over the aircraft, it will stick to your boots and clothing and get inside the aircraft. Ice is a similar problem or water on the ground that turns into ice in the air and yes similarly mud will freeze too. Plan accordingly, some handles about the airplane will aid in ground handling. Not very aerodynamic but there are some that push out of the airstream into tubes and crevice's unless needed. Insects, birds and rodents cause problems too.
 

blane.c

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HBA Supporter
Joined
Jun 27, 2015
Messages
5,002
Location
capital district NY
Okay I now understand you, I have been looking at not only the Piper Cub J3 and PA11 designs, but also at Fissler Storch, These are the current Plans and drawings i have been pouring over, I also understand that many tube sizes are used. I even watch tons of Mike Pateys videos, and to increase wing strength, I am thinking on his application of two wing spares, a forward and rear spare design. (i believe that is what he is doing on Scappy) So as i am in the research aspect of this at the moment. and trying to learn to use the Auto Cad programs I downloaded. (found FreeCad and Libre Cad online for free. and have 3D blender as well) Most of what i am doing now is pouring over the information, and coming up with a Plan of attack on the design. While i try to learn the programs, i do a lot of Graph paper drawing on ideas, and i have a stack of those.

Basicly, I am looking at any and all plans i can get my hands on for not only Ideas but studying them to get design concepts, even in my shop, I have poured over and even dysected some of the wings off my RC's .
The fixed slots on the Storch do not support flight at airspeeds above about and around 120mph. Late model Storch and Helio Courier had moveable slots to facilitate flight above 120mph.

There are examples like the Stinson 108-3 that have fixed slots and fly faster, but in the case of the Storch in particular there is a problem as previously stated.
 
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Victor Bravo

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Jul 30, 2014
Messages
9,521
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KWHP, Los Angeles CA, USA
Arkan, also remember that the Cub was designed by a very smart, but very small guy, and it was designed during a time when 10% of all Americans were standing in a line for hours to get a piece of bread or a bowl of soup.

So now in this day and age, a normal over-fed American has a lot of trouble getting in and out of the front a Cub. Even getting in the back is a little awkward.

So whatever you design, make sure you can get in an out easier than what a lot of previous designs offer.
 

Arkan

Well-Known Member
Joined
Jun 6, 2021
Messages
79
A few things to consider.

Most here will agree the most common reason for aircraft engine stoppage is fuel starvation.

Straining fuel that goes into the tanks is imperative but it doesn't hurt to have a good fuel filter system that will not starve the engine of fuel (it bypasses obstruction if necessary).

A crash resistant cabin is essential.

When the tail quits flying the airplane quits flying so it doesn't do any good to design a wing that fly's slower than that speed that can be supported by the rest of the plane.

Ailerons lose responsiveness first in slow flight, then the elevators, and finally the rudder.

You have to be able to hand prop the engine. Seriously some dumb*** is going to leave a switch on.

Tailwheels are under appreciated. They are drug through some awful things and no matter how stout do not look new very long in serious bush usage, but a wimpy tailwheel will disappear ... like magic

The main landing gear must be robust and should include adequate tires for inhospitable terrain and excellent brakes.

In bush operations you will have unexpected adverse conditions. Mud
Trying to take all this in order, so if I miss something I apologize.

I am planing on dual wing tanks, I have not figured on the size yet but I am shooting for at least 35 gallons, a fuel filter is definitely on the list of must haves and being able to bypass it is a helpful suggestion.

Crash resistance weighs hard on my mind, I do not currently Fly, and I am sure if I over shoot my weight goals, it is going to be in the name of safety. I used to race dirt track cars when I was younger. I have some ideas on adding strength to cabin from that experience. Things like triangulating impact points, adding gussets and brace plates. Also I am thinking on designing the from the firewall to the rear of the cabin like a race car roll cage. The trick is going to be working within weight restraints so the plane will actually fly.

The tail wing I have not put much thought in to yet, and I am sure there is a formula to determine tail wing size. I just have to find it. I do plan using an airfoil design on the vertical stabilizer. Elevator and rudder size I have not figured out yet.

I am seriously leaning towards Flaperons,from what I have seen and read, they don't wash out in a stall situation like traditional ailerons and flaps. Still making up my mind on this. They are easier to design from everything I have researched, but still debating in my head on the pros and cons.

hand propping is something I would be nervous doing, I am the type of dumb*** who would forget something like that, and actually did give some thought to this problem, I have always had the belief that two is one and one is none. So my thoughts was a back up battery system, but weight is an issue, so I will give thought to hand propping.

Tail wheel and landing gear, for the tail wheel, on the tail wheel suspension I am thinking on twin coil over shocks on a swing arm, also I am going to research the widest wheel possible, made caster style. I have seen on you tube guys burying and even kissing their tail wheels on bush flights. So I have given some thought to it and still thinking on that.

as for adverse conditions, is that not the fun of it all? This actually does give me something new to think on, keeping water and mud from freezing the control surfaces in place. Not being able to control the plane cause a chunk of my block my ailerons in place would be a sick factor I don't want to ever experience. I am planing on using a heater box much like a cars to give cabin heat and defrost abilities.

The fixed slots on the Storch do not support flight at airspeeds above about and around 120mph.
I am actually thinking on a deployable slat. I want to design bottom of the slat to form to the wing shape, and use a torsion arm to push them up and forward. When not in use they stow flat against the wing, the only worry I have is there is going to be a ridge when stowed that runs the length of the slat across the wing and again on the underside. I don't know how this will effect aerodynamic properties of the wing. This may be corrected with vortex generators..... maybe? Still putting thoughts in to this, and I don't even know if it is going to be a problem.


Arkan, also remember that the Cub was designed by a very smart, but very small guy,

So whatever you design, make sure you can get in an out easier than what a lot of previous designs offer.
I could not agree more! I am 6foot and weight 235 lbs, and when I see those carbon Cubs and how tight they can be, I cringe. So, I want a side by side front seating and I know I would want to be comfortable. So I want a wide cabin, and the doors I am still trying to decide. How to build the doors, but yeah, I don't want to have difficulty getting in or out..... I used to want to own a Corvette, until a friend got one and he let me drive it.... back then I was 280 lbs, did you know there is no graceful way for a big man to get in and out of one of those? First time I tried I fell flat on my face.
 
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Arkan

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Jun 6, 2021
Messages
79
Yeah... lol on my phone and auto correct hates me.... I noticed it and edited the post as you was posting
 

TFF

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Apr 28, 2010
Messages
15,345
Location
Memphis, TN
Any Corvette is easier to get in and out of than a dirt car. There is no dignified way to get in a plane unless it has stairs.

Flaperons can’t be deployed as deep as straight flaps and they are not usually as big. They have to accommodate the ailerons first. Ailerons are primary; flaps secondary control. What the real fancy planes do is they droop the ailerons partially and drop the flaps fully. Also all this is under air load. Some with fancy mixers, some with double hinge lines. The pilot only has so much leverage. More leverage means slower response, so there is a balance. No room or weight for power assist. There are some aero tricks to help. All a balance.

A carbon Cub is huge compared to a J3 width wise. Your dirt car analogy, most people are use to cars not sprint cars. Side by side with someone will be knocking shoulders, tandem let’s people have more of their own space. Both have drawbacks and advantages playing against each other. I would save up for a ride in a 172 and a Citabria if you have not experienced either; frame of reference. Fun too.
 
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