Why are a lot of jet models low winger inboard, high winger outboard?
Seems to add unnecessary structural design complications?
Hello Ian
Firstly I have to say that I have not designed any CL pulse jet models but I have built and flown them, so my comments below are from that position.
I would describe the 'on trend' models such as Blue Thunder, Tarfu and Pod Racer as mid inboard and high outboard.
Lets address the outboard wing first, this wing is there for more than a bit of show (I will dig out the aero justification later) but it is not working hard to create lift or anything like that so the structural requirements/demands are low and the fuz/wing joint is more than capable of handling these stresses. I would say that lift generated on the outboard panel is way less than 750 gram's.
Of course the reason for the outboard wing being high is to clear the jet tube.
I like the way that sidewinder jet models handle and in particular on take off, upright models have an 'off axis' thrust line that makes them stick to the ground more than a sidewinder, this can also be seen in some upright models when the jet stops that the model pitches up as the pilot is sub-consciously trimming the model to counteract the 'off axis' thrust.
Moving to the inboard wing, this really would seem to need to be positioned very close to the vertical CG. I think the Jim Booker Pod Racer has the inboard wing offset slightly in comparison with the Blue Thunder and Tarfu, we have seen Ken's Pod Racer bending the inboard wing when flying particularly when higher in the circle, I think Ken's later iterations of this model might have the wing repositioned but don't quote me on that.
I think that about answers the question.
Where is your buddy Jim Hammond?
Regards
Barrie
Hello Barrie.
Makes sense. thank you for the reply.
I think if I was making a jet model I'd leave off the outer wing, as in F2A models.
Ian
First thoughts are that you would leave the outer wing off, as you say like F2A style.
However here is what I think the problem is with that approach, the jets and in particular Fast Jet class models accelerate like crazy upon release and if you have all the model mass inboard of the engine then the model looks like it pivots around the wing tip where the lead out is.
The Morrisey-Hart Big Bird back in 2018 was vicious on take off, always swung in and cut the first 1/4 circle of flight.
The big IC models probably are not as quick off the mark as the jets.
Regards
Barrie
The easy answer for the wing being at the centre line of the model is you do not to have up or down built into the elevator as you would if the wing was above or below the engine. keeping everything 0-0 equates to a faster model. The outboard wing is just for show. The models i build for myself don’t have them as well as not having fins. It was a old wives tail that it helped with tracking. I will build what people want not what is practical. Regards Robert Bolton
You know what I think I'll have a little think about that...
Cheers, M'dears.
Hambone the inevitable.
@doc-james. Another bonus is having the fuel tank on the inboard side is always having a positive pressure when it goes faster.
Cheers
Robert
@noclassmac1972 Hey Robert, actually thats what I would have thought would be the logical layout.
In speed, clearly, the less gubbins you have hanging in the wind, the better.
What s the construction?
How does it fly?
Cheers,
J
