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What if though......


Guest francis777
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instead of pushing you had a puller prop? Forget the practicalities for a moment and think about being pulled instead of pushed. Would the same limitations on thrust apply?

Ok so what are the practical objections?

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instead of pushing you had a puller prop? Forget the practicalities for a moment and think about being pulled instead of pushed. Would the same limitations on thrust apply?

Ok so what are the practical objections?

not sure how pratical it would be, think about it, there will come a point where you will get to the limit of thrust that can be applied due to the fact the wing will no longer be able to move forward as fast as the motor, so until we get wings with massive speed our thrust will somewhat remain limited.

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instead of pushing you had a puller prop? Forget the practicalities for a moment and think about being pulled instead of pushed. Would the same limitations on thrust apply?

Ok so what are the practical objections?

Unburnt two stroke oil in your face :shock:

We would all look like they did in the old films

Pete b

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Uncomfortable prop wash! Not recommended I know, but have you ever stood behind a paramotor at full throttle?

The prop would have to be far enough away so that you could not make bodily contact but this would be unstable and unwieldy, not to mention harder to keep from contacting with the ground.

Thinking of a project Francis?

Best regards,

Ian.

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not sure how pratical it would be, think about it, there will come a point where you will get to the limit of thrust that can be applied due to the fact the wing will no longer be able to move forward as fast as the motor, so until we get wings with massive speed our thrust will somewhat remain limited.

The Bionic? tiny wing very fast needs an aerodynamic solution to the paramotor drag problem. But yes there is a limit (35 knts stall speed SPHG defininityion)

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Uncomfortable prop wash! Not recommended I know, but have you ever stood behind a paramotor at full throttle?

The prop would have to be far enough away so that you could not make bodily contact but this would be unstable and unwieldy, not to mention harder to keep from contacting with the ground.

Thinking of a project Francis?

Best regards,

Ian.

Nice try Ian but an aerodynmaic windshield/visor/fuselage would take care of propwash ans a shrouded prop or ducted fan (oops) would protect the pilot.

I mean what physics would make it a no no.

How far ahead of the pilot would be too far? Wheels and skids are acceptable on Doodlebugs and boosters for "prop protection" so you can put it out as far as you need to. On those machines the prop is well aft of the hang point. Could a puller be that far forard?

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seems interesting but i think it would take some genius to do it without danger and more safer than it is now, i think turbines might be a way forward two jets going over the shoulders to release thrust, or if we had a smaller prop that faced upwards would that be any better? i guess these ideas would at some point have been played with and stopped for bad design or just wont work reasons., i think a proppellor on ya back is very dangerous and would love to see some way of making it without or even covered in and the thrust diverted to were ya want it to go ,

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not sure how pratical it would be, think about it, there will come a point where you will get to the limit of thrust that can be applied due to the fact the wing will no longer be able to move forward as fast as the motor, so until we get wings with massive speed our thrust will somewhat remain limited.

The Bionic? tiny wing very fast needs an aerodynamic solution to the paramotor drag problem. But yes there is a limit (35 knts stall speed SPHG defininityion)

would the setup be any lighter than what we already have? if not then a small wing may not provide the lift to get it all of the ground, and then if it does the performance may be stunted by the extra wieght. then of course if you up the wing size you incur the extra drag

aviation has always had this challenge, how to go faster and further, going faster or further usually ends up adding more wieght to an AC, fuel, bigger engines etc

its general rule of aircraft design that for every 100lbs you add 100hp to keep things equal.

great minds have puzzeled over such problems since man first flew, hence we have such wonderfull creations as lifting bodies and custer wings.

:D

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instead of pushing you had a puller prop? Forget the practicalities for a moment and think about being pulled instead of pushed. Would the same limitations on thrust apply?

Ok so what are the practical objections?

Many many moons ago I read/heard something by http://en.wikipedia.org/wiki/Burt_Rutan and ended wondering why any props were still at the front. Sorry I can't remember the detailed reason or the source/paper/book :oops:

Cheers

Paul

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OK I'll give you that!

Phaeton II is taking form and I suddenly thought why not put the engine and prop at the front?

I have been looking at floating J bars with interest after flying a fresh breeze last month. It wouldnt take much to move the hang points in flight and produce the kind of dynamic weight distribution I've been looking for.

Phaeton I proved a bit cumbersome and too enclosed. I hurt my knee when it fell over and could find no way of redesigning it to prevent a recurrence. So I have turned the system through 90 degrees and the enclosure goes over teh top instead of round the sides'

I suddenly saw a possibility of making it a puller and wondered what the force diagram would look like.

PH20000106153931.jpg

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a) is actually quite simple. HABs are quite unpredictable. They are at the mercy of the wind/weather Gods. Almost more than we are. Get too close at your peril! (They cause their own wake because of sheer size and therefore need to be treated as a mobile hazard) I have planned a few things with HAB pilots for a couple of specific projects in the past.

2357296193_8a60462f0a.jpg

Also, if they need to ascend or descend in a hurry, they can effectively create their own thermal/sink by venting/burning. You DO NOT want to be directly over or under when that happens!

Stay a respectable distance and the pilot will love you because it gives his/her passengers something out of the ordinary to photograph and show their friends later. (My opinion only. Check with your local HAB pilot)

As for b) As I understand it, the ANO says you must not fly in formation unless all relevant pilots agree. Meaning you should all have confidence in the ability of the other pilots to not ferk it up.

As I said, that is as I understand it. Anyone with greater knowledge/experience please feel free to expand

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Definitely don't fly above or below a HAB, their acent and decent rates are very fast!. Can actually climb up to 700fpm!- much faster than a paramotor. In normal level flight with a balloon, generallly don't get too close 500ft would be close enough.

I cant understand how HAB's can generate wake? They're moving with the wind, they have no sensation of wind in the balloon, therefore how could a wake be generated?

GD

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Well unless the balloon was moving at exactly the same speed as the air mass, then you could expect turbulence. This presumably could happen when the HAB encounters slower or faster moving air and the balloons inertia would mean that quite a period could elapse before it accelerated or decelerated to wind speed. Also, as wind direction varies with altitude, then as the balloon climbs or descends it would have a vector that wasn't precisely in the same direction as the wind, so again, turbulence. Similar again if it encounters thermal lift/sink.

I should think that there are relatively few times when a balloon is truly a 'steady state' device. YMMV.

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