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Starman

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Hi everyone. Now that I've sold my aluminum vette engine and moved to the Southern Ecuadorian mountain wilderness I've started to think of what kind of special plane would be possible to use around here.

It has special needs due to the location it's designed for. There are no small airports around here, only big airliner ports in far away cities. I live in the mountains, very close to the crest of the Andes mountain range, at 7000 feet. There are no flat areas, only narrow ridges and steep slopes. There are times when it is calm, but there are frequent winds and wild wind gusts, that gets pretty serious during the dry (windy) season. I have a small flat area excavated on a local ridge/mountain top but it's exposed to the highest wind gusts there.

In order to fly in an area like this the following kind of aircraft is required.

This would be somewhat like an ultralight, a light weight single place plane of simple construction.

It has to take off and land at 20 mph or less.
It has to have a very fast roll rate even at low speeds.
It needs to have a very steep angle of climb and be able to nearly hang on the propeller(s).
It needs to have very reliable propulsion.
It needs to have great stability be stall proof, and have great ease of handling.
Long range is not needed.

There is a design I've come up with that should work well but I'm wondering what kinds of suggestion there are (besides "don't try it") concerning this type of mission requirement.
 

Hot Wings

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Are your firm on needing an "airplane"? It kind of sounds like a Gyro would be better suited to your requirements?
 

Starman

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The ideas I have so far on this is to use a 50 hp industrial engine driving a generator or alternator which feeds a battery, with the battery sending power to two electric motors, one on each wing. Having electric power to the two motors makes it easy to fold or remove the wings.

The engine, generator, and battery will all be located right behind the pilot in order to put the pilot in front of the wing for better visibility.

It should have large diameter propellers in order to give it a lot of thrust at lower speeds, giving it a nearly helicopter like ability to hang on the props or have a very steep climb angle.

Attached is the cartoon of the idea:
 

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Dan Thomas

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The ideas I have so far on this is to use a 50 hp industrial engine driving a generator or alternator which feeds a battery, with the battery sending power to two electric motors, one on each wing. Having electric power to the two motors makes it easy to fold or remove the wings.

The engine, generator, and battery will all be located right behind the pilot in order to put the pilot in front of the wing for better visibility.

It should have large diameter propellers in order to give it a lot of thrust at lower speeds, giving it a nearly helicopter like ability to hang on the props or have a very steep climb angle.

Attached is the cartoon of the idea:
7000 feet up in rugged, windy mountains is no place to be testing radical designs. The potential for a fatal accident is bad enough even in proven, capable aircraft in a place like that.

Dan
 

Starman

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7000 feet up in rugged, windy mountains is no place to be testing radical designs. The potential for a fatal accident is bad enough even in proven, capable aircraft in a place like that.

Dan
No worries Dan, I don't expect to be building any person carrying aircraft for the foreseeable future. Partly because I spent all my money on land and house construction. This is entirely an exercise in theoretical BS, maybe i should be making noise in the new low aspect ration thread instead.

Anyway, this XF5 copy is THE only real design that is suitable for the type of flying I would need around here. There are more flat and flatter areas not so far away, in the lower altitudes, but this is a dream about how I could get away with storing it and using it out of my own place.
 

Starman

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The RW19 or RW20 is the closest thing I can think of for your requirements at the moment.
Those are impressive in that they have stall speeds of only 15 mph! The problem is that they would not have the very fast roll rate at low speeds that would be needed to deal with mountain wind gusts, and they probably do not have the steep climb angle I would need either.

Also, I would rather not be seen flying in something that looks like those ... unless it was free.
 

TFF

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Aerobatic roll rates will not save you from mountain gusts. People who fly in those places fly like Zen masters. Cubs and Beavers are no aerobatic types and they dance in the mountains. FLying pancakes are interesting, but from the models I have flown of them, they dont handle like airplanes they have the impression of motoring around like boats.
 

Vipor_GG

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Those are impressive in that they have stall speeds of only 15 mph! The problem is that they would not have the very fast roll rate at low speeds that would be needed to deal with mountain wind gusts, and they probably do not have the steep climb angle I would need either.

Also, I would rather not be seen flying in something that looks like those ... unless it was free.
"closest thing I can think of"
I don't know of any aircraft that will cover all of your wants. Light aircraft and strong wind gust aren't a good combination. Fast roll rate at low speed and 20 or less mph stall isn't met by any aircraft I know of either. A 30' take off roll and 1200 fpm climb on 70-80HP is also impressive.

As for looks it looks pretty much like the average STOL.
 

Dana

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Low stall speed and strong gusty winds are a BAD combination.

Dana

Any man who can drive safely while kissing a pretty girl is simply not giving the kiss the attention it deserves ~ Albert Einstein
 

Aircar

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Actually I think that Starman has selected a quite promising configuration for his putative 'mountain top' airplane -- the XF5U was intended to land on platforms of warships and to go from zero (hover) to 500 MPH and would have likely done so if not scrapped prematurely --Boeing also investigated this approach and published a couple of similar designs but did not build them probably for the same reason as Vought ;- the advent of catapult and arrester gear on aircraft carriers and the coming of the jet engine.

The trouble with "storch" types is that they can ONLY land very slow which can be a big problem if trying to land in strong winds --the difficulty of landing 'backwards' is virtually insuperable (keeping flaps and slats up certainly helps but windspeed might even exceed the full throttle cruise speed in Andean winds --check out Antoine de St Exupery's writings on his South American flying for some idea of the velocities --admittedly this was ,mainly about far south South America rather than the milder equatorial region,but still...

The "Zimmerman/Arup" type is insensitive to gusts in that it doesn't stall until 45 degrees or so and even then has no sharp reduction in lift so has no tendency to roll off or snap roll/spin etc --to that extent it fullfills the criteria stated --the extent to which powered lift (slipstream) is to be relied upon determines the allowable wing loading --and thus the primary gust sensitivity . Getting enough forward vision at extreme angles of attack is the other consideration --Zimmerman favoured prone piloting and a transparent underside --one of his proposals had a gimballed pilot (like Nicola Tesla's related VTOL ) it works out best for overall vision and pilot insensitivity to gusts also . You could bury the pilot inside the wing root profile if prone -one of Zimmerman's unflown designs had only 7ft span but still much more wing area than say a BD 5 and of course vectored thrust plus slipstream 'supercharging' of the wing. There is much merit in the basic configuration (you can find quite a lot of data on the web now including the NACA reports on low aspect ratios by Zimmerman --I have an extensive collection of info on these type of aircraft if you find you need something specific and decide to go ahead .
 

BBerson

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"7 foot span" ? Maybe a wing suit would work for you in the mountains. Be the first guy to soar a wing suit :gig:

Seriously, the 50 hp industrial engine is extremely marginal in terms of power to weight ratio for aviation. Add a generator and electric motors, cables and electronic controllers.... Power to weight goes out the window.
 

bmcj

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"7 foot span" ? Maybe a wing suit would work for you in the mountains. Be the first guy to soar a wing suit :gig:

Seriously, the 50 hp industrial engine is extremely marginal in terms of power to weight ratio for aviation. Add a generator and electric motors, cables and electronic controllers.... Power to weight goes out the window.
There you go... a wing suit with a 50 HP industrial engine. :gig:
 

Aircar

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Bruce, --overlooking your incredulity , the thing that made that small a span possible was that (a) it was extremely light by virtue of the stocky shape, (b) the actual lifting area is not that small given that the span and chord are about equal (ca 40 sq ft of wing area) (c) no fuselage weight or wetted area-prone pilot (d) the wing tip props energize the flow over the wing so that lift is developed at slipstream velocity not forward speed (e) the wing planform confers an extended to normal lift curve to around 45 degrees not the usual 15 and it is useable because of the benign 'stall' and other factors -- in the event Zimmerman did not fly it which was due to the unreliability of the two stroke engines as reported (no cross shafting meant no fail safe engine loss ) Because of the 'square effect' it takes only a little more span to double the wing area (~1.4 times --eg 9.5 ft ) --so even if the smallness worries the first generation of pilots it can be 'crept up on' by progressive reductions as they become more familiar with such miniaturization -- the BD5 was a case of less wing area more wetted area and weight ,drag etc --flattening out the BD5 fuselage area into wing area would definitely tame such a 'widow maker' for no increase in drag . If you thought about how much ROTOR blade area there was per passenger in a big helicopter (or small one) you would probably be just as aghast -- yet it works (thanks to V squared) --in a 747 or the like you can unfold your handkerchief and stand on that to get an idea of what is holding you up . The F111 has a wing loading over 250 lbs per sq ft .............. putting the situation into some perspective helps to get a real idea of how 'hot' such an aircraft would be --- and conversely how little material could be used to transport a single person by air for daily mobility . With a new generation of electric batteries we could overcome the assymetric thrust issue and conceivably create something able to be mass produced and mass used --what is certain is that nothing costing remotely near the $250 000 range of typical light aircraft now (or so called flying cars now on offer ) could have any impact on real world transport having long since priced themselves out of the market .

A bit of blue sky thinking is not such a bad thing if it is founded on physical realities.
 

Starman

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Seriously, the 50 hp industrial engine is extremely marginal in terms of power to weight ratio for aviation. Add a generator and electric motors, cables and electronic controllers.... Power to weight goes out the window.
This Arup weighs around 800 pounds and seems to do fine on only 35 hp, and it doesn't even benefit from the wing tip props, see video.

I think with 80 or more hp available this type of design will fly well at it's weight. I guessing you could cruise well on 30 hp total, 15 hp per side. The battery is not for storing a lot of power so it would not be that heavy. It's for providing like 5 to 10 minutes of emergency power and occasional extra power only. The idea is that it will use more power on takeoff and climb, with 40hp per side available from the electric motors. The industrial engine, running at 50hp, will charge the battery during flight and once the battery is full it can be throttled back to 20 to 30 hp to keep the battery topped off.

Using electric motors at the wing tips makes for an easy direct connection, and a belt reduction drive will not have much in the way of resonance problems.

35 hp:

[video=youtube_share;Nxz1UF67EQI]http://youtu.be/Nxz1UF67EQI[/video]
 

bmcj

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Bruce, --overlooking your incredulity....
A bit of blue sky thinking is not such a bad thing if it is founded on physical realities.
Not sure how my wingsuit joke would be interpreted as incedulity toward the Vought, Zimmerman, or Arup designs. Personally, I like the concept of low aspect ratio planes (created and flew many low aspect models as a kid) and I'm a big fan of the V-173/XF-5U... would like to have seen the XF5 at least go through the test flight phase. As to the 7 foot, 2-cycle Zimmerman design, I'm not sure if I am familiar with it.

Bruce :)
 

Holden

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Starman,

Are there any roads in your area? Land on the road... Sorry, I could not resist...

You need push/pull twin. You need High AOA, which is easy with deltas. You need long gear stroke just in case the wind stops blowing.

The front engine is on at 75% during landing, barn door flaps on the delta, and tail(s) in back. The rear engine is used to control glide and is at low power. The front engine gives you CONSTANT power lift. The rear engine is the variable for glide. Barn door flap protects the rear prop from water and rocks.

Delta up top as well as engines. Pilot has great views and can see down and around. In cruise you can shut down front or back engine to get slow economy cruise.

As for the pancake, the twin engine on the sides requires a coupling as least, but that is not the least of the reasons you don't want to use side by side engines.

One engine needs to be on and the other nearly off. Lift needs to be a CONSTANT, but a glide path needs to vary.

It take a very skilled pilot to control an airplane "on the back side of the curve" with power on lift. Notice in the first video that the 23 mph was with the center engine and power on (lift coupled to power). By having a push-pull twin, the pilot sets the front engine power to some setting and applies flaps to counter the power. The drag of the flaps overcomes the power input such that the decent rate is 200-500 fpm as desired. Hence the need for barn door flaps... The rear engine is then used, just like any airplane does, to control glide path. The pilot does not feel like he is on the back side of the curve and can quickly adjust power to extend or shorten glide path and not have it affect the lift. The power on also creates a constant wind and therefore lowers the effect of wind speed changes in the flight path.

Even if you had the electric twin, a pilot will not be able to resist over controlling the power which is coupled to lift in the side by side pancake design.

Moreover, the pancake planform only allows one loading. Say you are alone and no cargo. Can you add or subtract wing? With a delta and panel wings, you can add in wing when heavy, and take them off when alone and light. This makes the airplane useful over a wide range. The power on lift keeps the landings speeds in the 30-35 mph even with light or heavy loads.

A push pull twin allows for a wide range of engines provided that are spaced for and aft equal distance from the CG. Need 80 hp? 150? 300? Not a big issue because is naturally balances. The electric system requires the engine to be on CG to have the option of different engines.

Another thing not realized is that at high AOA, the prop starts to yaw the airplane. The two counter rotating props in the twin pancake balance this, but props don't like to be at more that 15% of flow, hence the use of front engine with barn door flaps to keep the flow into the prop along the axis of the prop. The delta puts the engine out far enough to keep the flow parallel to the axis before it hits the flaps.

Last but not least, you want to use flaps to keep the cockpit LEVEL. The pancake does not have flaps that pitch the nose DOWN. Landing with the nose at 45 degree up is not what people want...



Sounds like what I am working on....

Holden
 
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