Engine angle on Kingcats, why ???
11-15-2010 | 10:27 AM
#26
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RE: Engine angle on Kingcats, why ???
Xairflyer, I like your explanation, seems intuitively correct. The problem is, when having a casual conversation about it at the field (or on RCU), it helps if everybody is on the same page with terminology. Lots of guys will look at a Reaction and ask, "why does it have so much DOWN thrust?" when it actually has up thrust.
This discussion reminds me about an article I read about early missiles with JATO bottles. IIRC, they would hang the missile in some kind of harness to find the exact CG location, then adjust the rocket nozzle angle to pass directly through the CG. This is an extreme case of power application at low speed, but seems related to our thrust line requirements.
This discussion reminds me about an article I read about early missiles with JATO bottles. IIRC, they would hang the missile in some kind of harness to find the exact CG location, then adjust the rocket nozzle angle to pass directly through the CG. This is an extreme case of power application at low speed, but seems related to our thrust line requirements.
11-15-2010 | 11:07 AM
#27
RE: Engine angle on Kingcats, why ???
ORIGINAL: Square Nozzle
Mike, if I read you correctly then I disagree with your thrust vector analysis. I agree that the nozzle facing down with the engine at the rear of the plane will push the nose down because the plane is rotating about the CG. If I keep that same thrust line and move the engine forward of the CG the nose will rise. Only if you turn the prop and thrust direction around. think about it again without moving the prop or altering the thrust direction, see Xairflyer's explanation post 25 he has explaind it better.
Efflux has been mentioned in several responses. Someone please explain to me what efflux is. Efflux is the high velocity air exiting the turbine exhaust. I think it refers to the effect on the horizontal stab with the high speed nozzle discharge air passing under the stab and elevator. The result, high speed - low pressure air below the stab and relatively slow speed lower pressure air moving above the stab forces the stab down.
ORIGINAL: BaldEagel
Consider the turbine wheel as a prop, does not matter if its in front or behind the C of G the thrust line stays the same whether pushing or pulling the reaction is also still the same.
If the turbine wheel and thrust line is pointing down at the rear, the reaction is for the nose of the airframe to Lower, now put that same thrust line on the nose of the airframe, still pointing down and still the reaction is for the nose of the airfame to lower, but the prop in conventional terms is pointing towards the sky, so its up thrust in conventional teminology with tractor propulsion which is the nomuculture.
Mike
Consider the turbine wheel as a prop, does not matter if its in front or behind the C of G the thrust line stays the same whether pushing or pulling the reaction is also still the same.
If the turbine wheel and thrust line is pointing down at the rear, the reaction is for the nose of the airframe to Lower, now put that same thrust line on the nose of the airframe, still pointing down and still the reaction is for the nose of the airfame to lower, but the prop in conventional terms is pointing towards the sky, so its up thrust in conventional teminology with tractor propulsion which is the nomuculture.
Mike
Efflux has been mentioned in several responses. Someone please explain to me what efflux is. Efflux is the high velocity air exiting the turbine exhaust. I think it refers to the effect on the horizontal stab with the high speed nozzle discharge air passing under the stab and elevator. The result, high speed - low pressure air below the stab and relatively slow speed lower pressure air moving above the stab forces the stab down.
11-15-2010 | 11:29 AM
#28
My Feedback: (1)
RE: Engine angle on Kingcats, why ???
ORIGINAL: BruceTharpe
Xairflyer, I like your explanation, seems intuitively correct. The problem is, when having a casual conversation about it at the field (or on RCU), it helps if everybody is on the same page with terminology. Lots of guys will look at a Reaction and ask, ''why does it have so much DOWN thrust?'' when it actually has up thrust.
Xairflyer, I like your explanation, seems intuitively correct. The problem is, when having a casual conversation about it at the field (or on RCU), it helps if everybody is on the same page with terminology. Lots of guys will look at a Reaction and ask, ''why does it have so much DOWN thrust?'' when it actually has up thrust.
Best solution especially for turbines would be just to say, angle the exhaust down or up whatever suits and forget about the terminology.
11-15-2010 | 02:33 PM
#29
My Feedback: (11)
RE: Engine angle on Kingcats, why ???
I have a bobcat with a jetcat p-120 when I built it I drilled the mount incorrectly for the length of the turbine which caused me to angle the turbine down even more with washers under the front screws. I flew it that way for 4 years with no problems then I started to fly off grass and a cloth material it caused lots of problems burning the grass and cloth runway. I re-drilled the mount and it is now 0 degrees down and it made little or no difference in flying if anything it has a better vertical.
11-15-2010 | 04:26 PM
#31
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From: lage zwaluwe, NETHERLANDS
RE: Engine angle on Kingcats, why ???
Mine flies perfect with a p200 and the original angel.
just look on the video
(on 3 min or 3.55 min it is extreme)
and also the angel of take off is perfect
http://www.youtube.com/watch?v=2QZqlkjFg4A
just look on the video
(on 3 min or 3.55 min it is extreme)and also the angel of take off is perfect
http://www.youtube.com/watch?v=2QZqlkjFg4A
11-15-2010 | 05:42 PM
#32
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From: Latrobe,
PA
RE: Engine angle on Kingcats, why ???
ORIGINAL: butler-campers
Mine flies perfect with a p200 and the original angel.
just look on the video (on 3 min or 3.55 min it is extreme)
and also the angel of take off is perfect
http://www.youtube.com/watch?v=2QZqlkjFg4A
Mine flies perfect with a p200 and the original angel.
just look on the video (on 3 min or 3.55 min it is extreme)
and also the angel of take off is perfect
http://www.youtube.com/watch?v=2QZqlkjFg4A
WOW. I've never seen a turbine take off like a fun fly model.
11-15-2010 | 07:38 PM
#33
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From: ZARAGOZA, SPAIN
RE: Engine angle on Kingcats, why ???
ORIGINAL: butler-campers
Mine flies perfect with a p200 and the original angel.
just look on the video[img][/img] (on 3 min or 3.55 min it is extreme)
and also the angel of take off is perfect[img][/img]
http://www.youtube.com/watch?v=2QZqlkjFg4A
After watch the video I guess you are from "The Throttle Benders Union"
My BobCat with P-120 needs 2 washers on the front bolt to get high speed low pass horizontal fligth.
My Boomerang Sprint with Wren 70 is at 0°-0°-0° and perform high speed low pass horizontal flight.
I guess that the location of the stab, near or far of the turbine flux is the question.
BR
Jesus
Mine flies perfect with a p200 and the original angel.
just look on the video[img][/img] (on 3 min or 3.55 min it is extreme)
and also the angel of take off is perfect[img][/img]
http://www.youtube.com/watch?v=2QZqlkjFg4A
After watch the video I guess you are from "The Throttle Benders Union"
My BobCat with P-120 needs 2 washers on the front bolt to get high speed low pass horizontal fligth.
My Boomerang Sprint with Wren 70 is at 0°-0°-0° and perform high speed low pass horizontal flight.
I guess that the location of the stab, near or far of the turbine flux is the question.
BR
Jesus
