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Dan Thomas

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It's power to weight ratio. I checked the C-150 manual. It needs twice the runway at 7500 feet and 32°.
So an ultralight that can take off in 50 feet at sea level would need 100 feet. Landing run is about half. The problem is takeoff.
Can you fly down a valley after lift off?
Landing run will be longer, too, as the true airspeed (and therefore groundspeed in zero wind) is higher. More momentum to dissipate.
 

blane.c

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Indicated airspeed required for flight remains the same, while ground distance for landing and take off will increase it can be amortized if taking off down hill and landing up hill. Of course climb performance will be affected by altitude in relation to sea level performance but any aircraft capable of normal cruise at 7 or 8 thousand feet will have normal performance after takeoff and would be able to climb albeit not as smartly as if taking off at a lower altitude.

There are trained fixed wing alpine rescue teams that cross a ridge and do a timed turn and land on or near the ridge top. This is much more daring than a well planned upslope runway.
 

Starjumper7

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It's power to weight ratio.
Ya, I know about power to weight ratio, which is why I brought up two stroke engines. It's also about reliability, fuel consumption (fuel weight), and the horrible noises that come from two stokes.

Can you fly down a valley after lift off?
Only by making an immediate 180 degree turn to the right after lift off.
 

blane.c

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I have taken off from ridges in my Cubby, Sometimes after landing and poking around for a few hours I would decide to spend the night and take off in the morning when (usually) the winds were calmer and it was more prudent. I would look for a slight depression in the area near were I landed and push the plane over so the main wheels were in the low spot and I would deploy and lock my spoilers to further thwart lift. Tying the plane down was often problematic but I always carried plenty of strong rope and tie downs which used along with local vegetation (usually bushes) always proved sufficient as I was serious about not having my plane ruined overnight. The tranquility of sleeping sometimes a hundred miles from the nearest village or settlement was unexplainable to those not so fortunate. The view in true dark of the night sky is awesome.

I have taken off under a lot of conditions.

After taking off I never remember feeling the necessity to do an immediate 180 degree turn, but that's just me.
 

blane.c

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If in a remote location and doing it from scratch today and both range and short field being a priority, I would build a motor glider of some kind. A glider typically has the lift needed and also spoilers which are truly under appreciated for bush work especially in high wind conditions. The glider portion of the aircraft is also a form of redundant power and I would like closer to 30 to 1 than 25 to 1 for glide more would be of course better. Personally being a multi-engine nut case I would have at least two sources of power because of the remoteness and because some places want asymmetrical thrust engines to both fail simultaneously they would need to be tandem.
 

Dan Thomas

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The tranquility of sleeping sometimes a hundred miles from the nearest village or settlement was unexplainable to those not so fortunate. The view in true dark of the night sky is awesome.
That there. That night sky on a moonless night is absolutely white with stars. Most city people have no idea. Sleeping in a tent in the rain or a thunderstorm is awesome, too. And eggs and sausage and spuds fried over a fire, with a bit of ash in them, washed down with with cowboy coffee, can't be beat.
 

Pops

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I grew up until 15 years old on a mountain ridge 7 miles from the nearest road and about 20 mile from a very small town. We didn't have electric until the county got a road right-a-way and built a gravel road in 1950, so getting a road and electric in the summer of 1950 was like going to heaven. In the summer the old shack of a house with 1/2" cracks in the floors and walls would be hot in the evening and grandfather and I would lay a blanket out in the grass and sleep outside under the stars until the house cooled off in the early morning. Always got up at 4 am to do the milking and feeding of all the farm animals. After the work, come to the house and fix breakfast on the wood burning stove at about 6AM.
 

Starjumper7

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That sounds ideal. When the house was being built here I lived in a little 10' by 10' wood shack with a tin roof. There was no electricity except for occasional generator use, no internet, and no woman. I think that was the best time of my life.

These days sometimes during the dry season I move a bed outside on the upstairs patio and sleep under the stars, which can be intense when you are closer to space, like we are.

Getting back to flying, there are times of the year when there is no wind and/or the winds are very mild.
 

blane.c

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It depends on your budget and concerns. The early plans built Slepcev Storch used engines other than the expensive one's more prevalent today. You could use a more reasonably priced power plant like an Aeromomentum Aircraft Engines, LSA, Experimental, Airboats, Aircraft Gearbox, 1300cc, 100hp, for instance but among many others. The Cub with modifications is an awesome performer and the Cessna 180/185 as well or more exotic the Helio Courier. All of these are single engine and engine failure in the Andes or surrounding area could lead to a forced landing or crash in inhospitable terrain. The DoubleEnder Project - Home (bushplanedesign.com) provides a viable solution and the idea could be grafted to many designs like the Storch for example which would be less expensive largely due to the fact that you can use less expensive engines.

Depending on the availability and ability to store aviation gasoline, engines that dependably use readily available car gas may be desirable. I have cruised many times at 15,000ft on car gas without problems. It is more difficult to detect water in the gas on preflight at least partially due to the fact that car gas isn't died like aviation gas but there are methods to overcome this AC20-125.pdf (faa.gov) .
 
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Starjumper7

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I like the idea of two engines, the engine choice is wide open since this is just a dream project, but my first impulse was to use an industrial V twin and add a powerful two stroke to help takeoff and initial climb as was suggested.

I made a sketch, maybe this will be worth a thousand words. This is my idea of a modified Zimmerman style which would be easier to build due to the straight lines.

The span is 20 feet, the center section is eight feet with removable six foot wings for ease of construction. Depending on balance, the V twin might be able to go as far forward as between or above the pilot's feet (or under the knees) The two stroke can be under and behind the seat with a drive shaft, which would be a flexible drive shaft to avoid torsional resonances. The wing area is around 300 square feet. It shows big giant all flying ailerons, for as fast as possible rolling ability.

A wing span of twenty feet is still a rather low span loading, so it should float rather well with the large wing area.

a2.JPG
 

blane.c

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People concentrate so much on "the wing" and "how slow it will fly aka their interpretation of stol" that they forget some of the more mundane and important aspects of a "Bush Plane". How does it handle in the mud? You will encounter mud and it is going to be all over the plane especially in the slip-stream and around the gear. Is your plane going to be able to take off so you can go somewhere and wash it or are you going to be stuck there until the mud hardens like an adobe brick and you can scrape off enough of it to go somewhere and wash it? Ground handling, is your plane going to be smooth all over and nothing to hang onto that wont break off or otherwise be ruined by ruff handling or will it have protuberances and handles that can be used to push it around on the ground especially when you are standing in mud the consistency of grease or ice and snow or possibly something unforeseen? When mud, bugs, ice, snow, or even rain are covering critical surfaces are you going to fall out of the sky or will the plane maintain lift? While no one should fly in such conditions on purpose situations unforeseen can develop and a sturdy craft that can trudge along is worth the penalty of some drag compared to a plane of cleaner design that won't trudge along. Aviation is a compromise remember. Metal props are widely considered superior for bush work. If you bend one you can often straighten it well enough to get you home vs a wood or fiber prop that may be shattered. Sturdy tall gear and tires is mandatory Alaskan Bushwheels | Original Off Runway Tires from Airframes Alaska "notice the valve stem in the sidewall of the tubeless tire" this prevents the valve stem from shearing off and the tire losing pressure when hard braking and the tire slips/rotates on the rim. BRAKES CANNOT BE OVER EMPHASIZED as well as the ability to kill lift as you cannot put the brakes on 3 feet in the air, so raise the flaps a little on flap equipped planes to get down a tich sooner or employ spoilers on non flap equipped planes. Also the ability to use the brakes without ruining the tires or nosing over is highly desirable. A cockpit designed to save the occupants is also desirable (any landing you can walk away from is a good one) this should include floor pan re-enforcement to avoid being stabbed to death by broken stubs of vegetation.
 

Starjumper7

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The wing is the thing, and this airplane is all wing. Mud is not a problem here except for in the parking area in front of the house, and the horses cause it by milling around. Mill, mill, mill. The airfoils would not be laminar, so the lift will not change much due to rain, and I wouldn't want to fly when it is rainy anyway. Bugs are rare at this altitude during the day. Grab handles for ground handling is a good idea, as are oversized tires. There is no where to land for a hundred miles except for the flat spot we made with an excavator, so this plane would not be for 'going places' and buying things, it is envisioned as being just to fly around the local area, taking off from and landing in the same place.
 
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