Sport Pilot Drifter story

[facthunter]

If you have a particular engine in front of you and it turns clockwise from your viewpoint, and you turn it around AND mount it behind you it will still blow wind AT YOU. To make it do the right thing you have to fit a prop with a different HAND (rotational direction) and the flat part of the blades still faces the tail. I reckon the Drifter engine/ tail relationship gives a bit of wind to both sides of the rudder. Different side at the bottom to the top.. It still swings ( not much) due to application of power. RESPOND to swing fairly quickly rather than anticipate it ( where you can get it wrong). It could be a wind gust or a stuck brake, or soft soil on one side. A drifter is a pleasant sort of thing. The most obvious aspect to it's control is a bit of adverse aileron effect when you try to roll quickly. which you get used to and plenty of aircraft have.

 

If it got tail heavy it would be something different. If you are light ( Like Tomo) you need a weighted cushion under you in the front. Nev

 

 

[farri]

If my original posts have been read correctly the reader will see that I`ve talked about an engine with gearbox and shaft turning in the same direction not an engine where the prop is being driven directly off the crankshaft.

 

What I havn`t talked about is Weight and ballance and the four forces created by the rotating propeller.

 

Frank.

 

 

[facthunter]

I think most English direct drive engines are anti- clockwise from the cockpit. I prefer to consider it from the drive end., having #1 Cylinder at the drive end too...American direct drive are usually the opposite. Geared engines can be anything but they normally reverse the engine's direction, ( with some exceptions like a Pobjoy). Just a bit of useless information for you. Nev

 

 

[farri]

I`ve gone over all the posts I`ve writen previously, in reply to other posters on this thread and the conclusion I`ve come to, is, " I wish some of you guys who have replied to my posts would read them carefully before replying."

 

I got back into this discussion because when I loged on today there was an optimistic symbol on my post #21. It left me wondering " Why optimistic?" .... Though I`ve asked, I haven`t got an answer yet from the guy who put it there or anyone else. I`d still like to know.

 

Can anyone please tell me just what the topic of this discussion realy is?

 

This thread should be in 'General Discussion

 

Frank.

 

 

[skeptic36]

Can anyone please tell me just what the topic of this discussion realy is?

Frank.

It is about why the prop slipstream makes rudder input necessary on a drifter.

In your post number 11 you say : the slipstream will rotate around the aircraft and strike the verticle fin and rudder on the left hand side,causing the aircraft to yaw/swing to the left, on applying power on take-off.

 

That is exactly what I didn't get, it's rotating so why is there not pressure applied to the port side of the rudder at the base and similar pressure applied to the top of the starboard side. Having looked at a pic of a drifter I'm thinking it is because slipstream on the starboard side is going over the top of the rudder.

 

Regards Bill

 

P.S don't lose too much sleep about the optimistic thing its easy to press the wrong button on an iPad if your fingers are big.

 

 

[farri]

It is about why the prop slipstream makes rudder input necessary on a drifter. In your post number 11 you say : the slipstream will rotate around the aircraft and strike the verticle fin and rudder on the left hand side,causing the aircraft to yaw/swing to the left, on applying power on take-off. Regards Bill..P.S don't lose too much sleep about the optimistic thing its easy to press the wrong button on an iPad if your fingers are big.

Bill thank you for your reply, it allows me to clarify a few things. I`ve copied these two paragraphs from my post, number #11. Take a look again at what I did say in that post. I apologise if I worded my post in a way to give you or anyone else the impression that I was talking about the Drifter when talking about the slipstream striking the verticle fin on the left hand side. In fact, I was talking about an aircraft with a front mounted engine. All the Drifters I have seen have had a clockwise ( When looking forward ) rotating prop and I didn`t see the need to point that out.

 

"Havn`t read the article but anyone who knows their theory will know that a right hand rotating prop on a front mounted engine, is furthur away from the verticle fin and rudder than the rear mounted engine on the Drifter,therefore, the slipstream will rotate around the aircraft and strike the verticle fin and rudder on the left hand side,causing the aircraft to yaw/swing to the left, on applying power on take-off."

 

"Due to the engine on the Drifter being so close to the verticle fin and rudder, most if not all of the spiral of the slipstream will strike the fin on the right hand side and the AC will yaw/swing to the right as power is applied....Yaw is not corrected, simply by applying left rudder...Both feet have to work in coordination to keep the AC going in a straight line."

 

I can assure you I will not loose any sleep over the 'optimistic' or any other symbol placed on my posts, however, it concerns me if I`ve posted something that is incorrect or misleading. I would rather be corrected by someone, than left wondering what is meant by some ambiguous symbol on my post.

 

Then there`s the issue of the pusher/tractor prop. Someone might like to elaborate furthur on that subject.

 

Frank.

 

 

[Teckair]

Most modern Rotax engines have a reduction gearbox with two gears being used meaning with that set up the prop will always rotate in the same direction, opposite to the crankshaft rotation.

 

With a pusher set up when viewed from the rear the propeller will rotate in a clockwise direction, with a tractor configuration the prop will will be rotating in an anti clockwise direction when viewed from the the back.

 

Changing to a tractor configuration if the propeller fitment is not changed it will still act as a pusher and try to push the aircraft backwards. If the propeller is refitted facing the opposite direction the rotation direction will not change but now the propeller will be rotating the opposite way it is designed to this means the trailing edge of the blade becomes the leading edge and the leading edge becomes the trailing edge. The result will be the propeller will still act as a pusher and try to push the aircraft backwards but due to the prop rotating the opposite way it is designed to it will be highly inefficient.

 

 

[Teckair]

Frank is correct with what he has said about the swing of a drifter when power is applied and the height of the propeller is factor. Because the prop is close to the vertical fin/rudder and mounted high mainly the bottom half of the prop wash affects the fin/rudder with the right hand side going down the right side of the fin is affected causing the plane to want to swing to the right

 

 

[facthunter]

I don't think there is any disagreement with those two posts Teckair.

 

Regarding Farri's concern with clicking the icon as "optimistic or amusing" when one is trying to make a serious point can be taken as disparaging of the post. The last time I mentioned this it was said that an error or slip of the keyboard is nothing but If one does that, a qualification/explanation is not too much to ask.. We do try to address some very personally held beliefs and explanations here and go to some effort at times to get the message across so it is not ambiguous. Not always an easy task. (Much easier if you are doing a Power point presentation or such). Nev

 

 

[farri]

Assuming the shaft is rotating in the same direction, (both pusher and tractor), the prop is bolted on one face of the hub for the pusher and the othere face of the hub for the tractor. In both cases the the prop will face and spin in the same direction.Frank.

It`s going to take a bit more to convince me that a prop that can be bolted on either the front or the back face of the hub, can`t be used as either a pusher or a tractor, provided the prop shaft in both cases is turning in the same direction.

 

On the rear mounted engine ( Pusher ) the front face of the hub of the prop is against the flange of the prop shaft.

 

On the front mounted engine ( Tractor ) the back face of the hub of the prop is against the flange of the prop shaft.

 

If the prop is taken off the pusher and move forward to the tractor, nothing about the prop has changed other than it will be bolted from the front face of the hud. The aircraft must go forward.

 

Frank.

 

 

[Teckair]

FH said... I don't think there is any disagreement with those two posts Teckair.

 

Looks like you are wrong about that.

 

 

[facthunter]

I agree with you, anyhow. Also I have been wrong before. Regarding farri and the prop, I also agree with him, provided the two faces of the hub are appropriate it should work as a tractor or a pusher as long as the flat face faces toward the back and the rotational direction is correct for the prop. If you keep talking about this for long enough you will go crazy. Nev

 

 

[Teckair]

I agree with you, anyhow. Also I have been wrong before. Regarding farri and the prop, I also agree with him, provided the two faces of the hub are appropriate it should work as a tractor or a pusher as long as the flat face faces toward the back and the rotational direction is correct for the prop. If you keep talking about this for long enough you will go crazy. Nev

That is so true you have to know when to walk away, as Frank said this thread should not be here anyway.

 

 

[farri]

If you keep talking about this for long enough you will go crazy.

This is a public forum that can be viewed by anyone connected to the internet, anywhere on the planet. It is not a conversation between a couple of blokes on a street corner. If incorrect information, be it mine or anyone else`s is posted then by talking it through, hopefully the correct information will finaly emerge.

 

That is so true you have to know when to walk away.

I will not walk away from an issue when I know I am correct and I hope others don`t either.

 

Frank.

 

 

[facthunter]

And I trust you don't Farri. I just found myself being in a difficult place trying to explain it easily. With a model or blackboard it would all be a lot easier. The written word is hard to exclude ambiguity from. Pretty easy to have misunderstandings on a forum . I'm sure you have noticed that yourself..Nev

 

 

[Teckair]

And I trust you don't Farri. I just found myself being in a difficult place trying to explain it easily. With a model or blackboard it would all be a lot easier. The written word is hard to exclude ambiguity from. Pretty easy to have misunderstandings on a forum . I'm sure you have noticed that yourself..Nev

That is very correct Nev in post 32 I explained step by step why it would not work and still we have this.

 

Frank I probably should have mentioned this before but the reason why I know is because I have tried it many years ago while I was still at school with a model aircraft. Back then I had the same response from the school teacher who thought the same as you and a black board was used to demonstrate how it works. At the time I was trying to make a flying saucer for filming purposes and found that tractor props are different to pusher props. I suggest you read post 32 and understand it as it explains what happens.

 

Sooner or later you will find you are wrong about this.

 

Richard.

 

 

[farri]

Regarding farri and the prop, I also agree with him, provided the two faces of the hub are appropriate it should work as a tractor or a pusher Nev

Nev, Have you changed your mind?

 

With a pusher set up when viewed from the rear the propeller will rotate in a clockwise direction, with a tractor configuration the prop will be rotating in an anti clockwise direction when viewed from the the back.

Richard, I have said from the very begining, the prop shaft must be turning in the same direction in both configurations.

 

At no time have I sugested putting a prop from a shaft turning clockwise to a shaft turning anticlockwise and expecting the same result. I am aware that not all props can be bolted on either side of the hub.

 

Sooner or later you will find you are wrong about this.Richard.

My first prop was an Ultra Prop. My second prop was a Brolga. Both props could be bolted on either side of the hub as both sides were flat and exactly the same.

 

This is not a game to me. I`m not about trying to proove who is smarter than who, I`m only interested in the facts and so far no one has given me an explanation or facts, to the reason why a prop that can be bolted from both sides of the hub, can`t be used as a pusher or tractor.

 

Frank.

 

 

[facthunter]

Franco, I think we are saying the same thing. Nev

 

 

[Teckair]

My first prop was an Ultra Prop. My second prop was a Brolga. Both props could be bolted on either side of the hub as both sides were flat and exactly the same.

 

Yes but you would never have tried to use them as a tractor prop or we would not be having this conversation. Can I ask you to tell me what part of post 32 you don't understand or think is wrong?

 

 

[farri]

Yes but you would never have tried to use them as a tractor prop or we would not be having this conversation. Can I ask you to tell me what part of post 32 you don't understand or think is wrong?

 

Richard, What makes you think I don`t understand your post *32 or that any part of it is wrong? I learnt what you are saying 30 years ago.....It appears to me that you havn`t understood what I`m saying, and have said, from the begining of this thread.

 

I`ve just got off the phone to Brolga-Bolly Aviation and my question to Peter was very specific, " Can you use the same prop for a pusher and a tractor, provided the prop shaft rotation is the same in both cases?".....His answer was "Yes, you can."

 

Wheather or not I have tried to use my prop as a tractor prop, has no relevance to what I`m saying. I know for a fact that it can be bolted from both sides of the hub face. Performance of the propeller is another issue completely and to discuss that we need all the factors involved in the particular situation, not just a general discussion, without any facts.

 

Frank.

 

 

[Teckair]

Frank I do not wish to have a falling out over this. I do under stand what you are saying about bolting the prop on either side of the hub face but it will still act as a pusher for the following reason.......

 

With a pusher set up when viewed from the rear the propeller will rotate in a clockwise direction, with a tractor configuration the prop will will be rotating in an anti clockwise direction when viewed from the the back. Taken from post 32. In that post I explained step by step why it would not work and think the only reasons why you would not accept that would be if you thought the theory was wrong or you did not understand it.

 

What amazes me is nobody has jumped in here and contributed to this. Is the general knowledge really that light on in this area? Looks like I will have ring Bolly and try to find out why he told you that.

 

I don't know if you can some how rearrange the blades on a ground adjustable prop but I don't think so. Certainly with a one piece wooden prop it has to be either pusher or tractor and will not work as both on the same engine/reduction drive configuration.

 

Richard.

 

 

[facthunter]

If you put a prop on backwards it still works in the same sense but with the efficiency reduced. Like a lifting wing section flying upside down. The wing should have the flatter side to the bottom, The prop should always have the flatter sides of the blade to the rear, regardless of tractor or pusher. Then you have to determine if the helix of the prop is right for the engine's direction of rotation. nev

 

 

[Teckair]

OK spoke to Peter at Bolly who explained that yes a Bolly prop will do both tractor and pusher but you have to rotate the blades 180 degrees in the hub as well as refit the prop with the opposite hub face towards the gearbox to make the change.

 

If you cannot do that (as with any fixed pitch prop) it will not work.

 

Richard.

 

 

[Karl]

Hi teckair I'm new to this side and new to flying and normaly only read and not commend on post because my limited piloting time

 

However I also get a bit frustrated with this.

 

I can compare turning a propeller around and trying to go from tractor to pusher with a fan I had in my piggery and with not much thinking turned the blade around to try to change it from sucking to blowing.

 

When I turned the power back I found that the air was still moving the same direction.

 

I think you could only use a propeller form a tractor configuration on to pusher if the pusher engine turned the opposite direction of the tractor engine viewed from the fly wheel end,or the engine has a flywheel on both ends where a prop could be bolted on.

 

Karl

 

 

[Teckair]

Yes Karl you are correct.