# Project Bush Demon

### Help Support Homebuilt Aircraft & Kit Plane Forum:

#### rv7charlie

##### Well-Known Member
Well I live in Westville Ok, due Due Wedt of Fayetteville, just across the state line.... he isn't an CFI is he?
Not a CFI; engineer teaching at the U.

#### rv7charlie

##### Well-Known Member
Here is a question.... how difficult is it to insure a home built?
There really isn't an answer to that.
a/c type: well known will cost a lot less; a 'one off' or relative unknown or one with a bad rep will cost a big percentage of the value.
pilot experience: pretty obvious on this one
insurance industry losses in recent years (not just a/c losses): more losses, even in other risk areas, drive premiums up
investment markets: insurance companies make their real money through investing our premiums. If they think the near future looks good for their investments, rates come down. If they suspect that they've been riding a up-wave for a long time & they think it can't last, they'll start raising rates (that's happening right now).

Unknowns drive the underwriters up the wall. Right now, a brand new pilot in a brand new design homebuilt would likely find it nearly impossible to get hull insurance. He might be able to get liability-only, and a significant premium penalty over what it would cost for say, an RV-x flown by a 500 hr pilot with 100 hrs in type. Now is a tough time for low time pilots. There's an low time RV driver on another forum that was recently quoted $5,000/yr for coverage similar to what I have on mine, for which I pay ~$1150/yr (I've got ~600-700 hrs in RVs).

#### Arkan

##### Well-Known Member
It really is a crying shame... I went to Walmart today to find a few supplies, they used to sell a large graph paper tablet, protractors, compass, etc etc for those who drafted the old way. Anyone want to guess what I found? If you guessed none of the above, your correct.

#### Tiger Tim

##### Well-Known Member
I went to Walmart today to find a few supplies...Anyone want to guess what I found?
That’s okay, you probably have a small teaching supply or art supply store nearby that has what you’re after. Put some money in their pockets instead.

#### TFF

##### Well-Known Member
School is out so about another month before they really care to restock that type of stuff.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
Arkan, even the world's best, most educated, most famous airplane designers usually start by putting a bunch of known components together, then they calculate and test and determine if and why and how any of those components need to be modified.

And like Senator Lloyd Bentsen said to Dan Quayle... Senator, you're no Jack Kennedy.

So whatever the hell you do, start with a known, proven, predictable wing airfoil. The one you drew will not fly well at all, I'm sorry.

Designing an airplane as a mental exercise is a perfectly good pursuit, but it doesn't mean you also have to design a new airfoil, design new tires, design a new type of plastic for the windshield, design new bolts, etc.

#### Arkan

##### Well-Known Member
Arkan, even the world's best, most educated, most famous airplane designers usually start by putting a bunch of known components together, then they calculate and test and determine if and why and how any of those components need to be modified.

And like Senator Lloyd Bentsen said to Dan Quayle... Senator, you're no Jack Kennedy.

So whatever the hell you do, start with a known, proven, predictable wing airfoil. The one you drew will not fly well at all, I'm sorry.

Designing an airplane as a mental exercise is a perfectly good pursuit, but it doesn't mean you also have to design a new airfoil, design new tires, design a new type of plastic for the windshield, design new bolts, etc.
You are right VB, what I drew that day was me screwing around at work, I have been studying different designs, I have been giving thought to an elliptical wing with flaperons.... I know the stall characteristics run with the wing and start at the trailing edge. Using flaperons might off set that seeing that they are lower and in clean air. Might work.... I know the British put a slight twist in the spitfires wing I don't think it helped with stall speeds, but it did make the airplane shake a bit or did something to let the pilot know she was going to stall. Also I do t know what effect VG's would have on an elliptical wing.

#### TFF

##### Well-Known Member
You twist a wing so the outboard stalls last. Ailerons are outside so there might be one little bit of control before the bottom falls out. If you are doing stalling on purpose is one thing, but surprise out of control, you need all the help you can get. Of course if you are a crazy aerobatic show flyer, you want the reverse so snap rolls can be crazy fast alongside anything else you can use to make vertigo fun. That’s why drooping ailerons should be done in stages compared to flaps or limit flapperons so you don’t get hungry for that, if I had a little bit more, wish.

#### Arkan

##### Well-Known Member
I have a chance to buy an old Stinson fuselage. Tube chassis, it is covered with landing gear and wheels for 850. Maybe this could be the basis for my bush demon. I am learning, getting my pilots license, so building a wing for the plane, or even buying a set to rebuild? Stinson 108. Could be a fun build. Could beef up the suspension and tail wheel assembly, or maybe build a scratch built copy... but 850 for a fuselage, that's cheap.

#### blane.c

##### Well-Known Member
HBA Supporter
Stinson 108 had 165hp Franklin engine ... underpowered ... they work well with more powerful engines around 220hp. There are STC's for bigger Franklin 220hp or Continental O-470. Trouble is heavier engine = less useful load and higher fuel consumption so less range. They look cool. You will have more fun in something else I think.

#### TFF

##### Well-Known Member
For experimental, the FAA frowns on using big stock parts. If you want it to be experimental, you will have to change it up some. Restoring it to certified would probably be very expensive. You on a fine line if it’s recognizable as a Stinson. You can copy one to be experimental, but the FAA will want documentation you made every inch.

#### Arkan

##### Well-Known Member
Stinson 108 had 165hp Franklin engine ... underpowered ... they work well with more powerful engines around 220hp. There are STC's for bigger Franklin 220hp or Continental O-470. Trouble is heavier engine = less useful load and higher fuel consumption so less range. They look cool. You will have more fun in something else I think.
Well could base my design off the Stinson, make the cab a little wider, lengthen the chord of the wings, if I built a tube chassis with chrome moly tubing, I could lighten the airplane considerably... something to be said for modern materials. I am thinking on using areomomentum engines. So building around that, and using the Stinson design or at least shape. I could be on to a winner. Maybe round the edges a bit to reduce some drag.... dunno, my ideas are all over the place right now I guess.

I just want to fly... call me crazy, but after finding a flight instructor I can afford, my brain is shifting gears from mental exercise to build a plane. I guess it is a logical progression. Increasing knowledge and figuring out ways to do different things, well this is going to be an adventure.

#### Tiger Tim

##### Well-Known Member
Well could base my design off the Stinson... if I built a tube chassis with chrome moly tubing, I could lighten the airplane considerably...
It’s unlikely that you’ll save weight by making a steel tube fuselage to replace a steel tube fuselage, but I’ve been wrong before.

#### blane.c

##### Well-Known Member
HBA Supporter
Before you buy it, weigh it. And then really think about it.

#### Arkan

##### Well-Known Member
It’s unlikely that you’ll save weight by making a steel tube fuselage to replace a steel tube fuselage, but I’ve been wrong before.
I don't know, the alloys we have today are way lighter than in 1947. Using the Stinson as a base design and incorporating modern build techniques and materials should produce a lighter aircraft at the end of the day.

One idea I had was using aluminum cut bulk heads through the fuselage. Citing them and bead rolling them to add strength, then riveting them to a flange on the lateral runs of tubing down the length of the fuselage. You can round the corners more this way and reduce the amount of steel used. Still thinking this one out in my head..

#### TFF

##### Well-Known Member
If you take the landing gear and fin off and just had the fuselage, it’s probably 150 pounds. If you change to aluminum parts to be structural and have to mechanically attach with rivets or bolts, you will loose lots of advantage just because mounting will be much bigger footprint than a little weld. Most airplane materials are the same from 1947.

#### Arkan

##### Well-Known Member
I had a thought, would there be anything wrong with using carbon fiber for the wing ribs, having a chunk of aluminum precision cut for the outer shape. (Got this idea from Mike Patty's slat design). Then laser cut foam board and cover in the carbon material and use heavy weights to press it into the mold. This could produce a strong wing rib and be light on weight. Only problems I see are, from what I understand, carbon fiber interferes with radio communications?

#### blane.c

##### Well-Known Member
HBA Supporter
I had a thought, would there be anything wrong with using carbon fiber for the wing ribs, having a chunk of aluminum precision cut for the outer shape. (Got this idea from Mike Patty's slat design). Then laser cut foam board and cover in the carbon material and use heavy weights to press it into the mold. This could produce a strong wing rib and be light on weight. Only problems I see are, from what I understand, carbon fiber interferes with radio communications?
Some glues with the carbon fiber corrode the aluminum, so chose carefully. Aluminum immediately bonds with oxygen when a fresh surface is exposed to air, this means the glue is attached to a oxide instead of pure aluminum weakening the bond. There are ways to minimize, less $, and ways to put a coating on the aluminum that is molecularly bonded and to glue to that, more$.

#### blane.c

##### Well-Known Member
HBA Supporter
The whole J-3 cub empty might way around 600lbs. It hadn't enough hp to do work wanted so more hp and more weight were added eventually we have 1400lb with mods and bells and whistles PA-18's. You can have a nice simple experimental cub clone no electric with 160hp engine for around 900lbs and 900lb useful load. It is the useful load/hp part that is important. The aircraft has to support the weight of the work you want to do and the hp drags it out of the bushes. There is not a free lunch here.

#### Arkan

##### Well-Known Member
The whole J-3 cub empty might way around 600lbs. It hadn't enough hp to do work wanted so more hp and more weight were added eventually we have 1400lb with mods and bells and whistles PA-18's. You can have a nice simple experimental cub clone no electric with 160hp engine for around 900lbs and 900lb useful load. It is the useful load/hp part that is important. The aircraft has to support the weight of the work you want to do and the hp drags it out of the bushes. There is not a free lunch here.
I think airplane design in general is a trade-off. I look through everything I can get my hands on. I found a site with a lot of downloadable PDF's Plans for Everything - Aircraft Plans

I look through these, and others I find. Taking ideas from one, adding them to others. I watch probably every build video I can find on YouTube (honestly some of these guys should not be making videos, they either have no personality, no clue or no real information. I love Mike Patey's videos but if your like me, you don't have access to a million dollar precision water jet cutting table. Also I can draft all day long on paper. I have not a clue on how to enter that into a computer. I think the problem is the programs are written by programmers, who have not a clue on how to draft. Lol.

So far it has been a long process to figure out. On another note, it is hard to focus on which way to go in the design right now, got some medical test coming up next week and my Son coming to visit for the next month. He wants to help me with the plans for the plane. He thinks designing a plane is cool and thinks I am brave for taking steps to learn to fly. (He is scared of heights). Honestly, I am trying to find a new balance in my head as well. I my change the bush plane idea to something I can fly to see my kid. He is 750 miles away by road. So maybe something that I can fly down with one stop for fuel, it doesn't have to be super fast. Say 800lb to 1000lb payload two seat airplane. Say it cruises at 120 or so, I could get down there in 6 hours or so plus time for fueling in route. Don't know, this would be a more practical direction.