> That is because the glider actually accelerates momentarily on entering lift. > Draw the diagram and remember that the lift vector is at right angles to the > relative airflow. The time constant for this is around 0.5 seconds for a > modern ballasted glider so after a bit over a second most of the effect has > gone away.
Interesting that with model gliders, you can see the tail rise quite clearly. Same mechanics, just more amplified as the tails on HLG in particular, are very light. If you watch a full size glider low and close to the field, when it meets rising air you can see the tail rise. Conversely you can also see when a glider is in sink…dragging its sorry arse all over the place, Once this effect is bought to a pilots attention they can learn to recognise and respond appropriately . The vario however needs to be at very low volume so that the pilot is not swamped its distraction and preventing useful physical signals being recognised while waiting for the vario to bleep well after the aircraft has departed the rising air. > Most people are flying attitude and will automatically pull the stick back to > maintain the attitude. Unless they are attune themselves to the feeling they will miss it. Its a subtle signal that can be made more obvious by design and CoG placement > This results in them feeling like "the tail is being pushed up" as they pull > back. If you are turning and the thermal is strong and you are too keen to > maintain the attitude you can stall the wing(s), spin and try to kill > yourself. Really, and how often does that happen….must be trained otherwise then... > >> The dynamically and statically lighter the tail is, the faster it will rise >> (it rises in response to the change of angle of attack caused by the rising >> air). The faster is rises the easier it is to feel. >> >> A nose heavy CG slows the âriseâ response making it harder to feel the >> lift, this is most prominent when seeking bubbles and lines than big >> thermals. > > > Wrong way around. Forward C of G makes the glider more statically stable. exactly what I said, a fwd CG means more positive force being applied on the tailplane (creating strong stability and resistance to external forces) and making the stick force required to change the A0A greater (giving the glider that heavy feel) A rearward CG makes the controls lighter (which you can easily feel if the CG is back with the controls being lighter and more sensitive) and as such the dynamic forces in place are less, so when the plane goes into rising air the stabilising setup will renormalise the AoA by raising the tail more quickly than if it has a forward CG…ie less signalling to the pilot > I was in Germany in 1988 when the SB13 flying wing glider flew. They were > pretty cautious and had a forward C of G and being a wing it had a low moment > of inertia around the C of G in the pitching direction. It proved unpleasant > to fly like that as it reacted too quickly to up and down gusts so they ran > the C of G aft to make the static stability more neutral. Flying wings are like that. A short moment has its downsides. Building stability into single wing seems to have tradeoffs greater than employing a tailplane (which there days are tiny) A good question to ask is why have tailplanes got smaller and booms lighter and smaller. Easily seen by anything new from the factory of recent design > > Mike > > > > > >> The diana 2 is know to be able to signal lift very well, this is likely why. >> (it has very low tail and boom mass, and less inertial and therefore faster >> to respond) >> >> >> >> >> >> >> >> >> Richard Frawley >> [email protected] <mailto:[email protected]> >> >> We do not inherit the earth from our ancestors, we borrow it from our >> children >> >> >> >> >> >> >> >>> On 17 Jan 2019, at 10:43 am, Nick Gilbert <[email protected] >>> <mailto:[email protected]> > wrote: >>> >>> Mike, >>> >>> Iâm sure this is the wrong answer, but to me it feels more comfortable >>> slightly nose high - so yawstring indicating right rudder required if >>> turning right. I fly with forward c of g which may be a factor. >>> >>> I have no idea if this is more or less efficient, and Iâm under no >>> impression that itâs the optimal method. Just that it feels more >>> comfortable. >>> >>> Nick. >>> >>> On 17 Jan 2019, at 10:09 am, Mike Borgelt < [email protected] >>> <mailto:[email protected]>> wrote: >>> >>>> Yes, to be pedantic it is trailing but common vernacular is to call the >>>> back end of the yaw string the direction it is pointing. >>>> >>>> Now can someone answer the questions please? >>>> >>>> When circling in a thermal, do you >>>> a) keep the string centered >>>> b) fly with it pointing to the outside of the turn >>>> c) why? >>>> >>>> >>>> Mike >>>> >>>> At 09:12 AM 1/17/2019, you wrote: >>>>> Mike, >>>>> In your original question, >>>>> >>>>> Part b, >>>>> >>>>> By "pointing" I presume you mean "trailing" ? >>>>> >>>>> To me, in this case "pointing" could be the direction of the forward end >>>>> of the string.Ã >>>>> >>>>> >>>>> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt < >>>>> [email protected] <mailto:[email protected]> >>>>> wrote: >>>>> So how about answering the questions? >>>>> >>>>> Mike >>>>> At 08:51 AM 1/17/2019, you wrote: >>>>>> >>>>>> and what is the expected differential (gain/loss) with say a 10degree >>>>>> slip indication variation, given all the other factors that determine >>>>>> climb rate. >>>>>> This might b able to be worked out mathematically given the airflows >>>>>> angle on the wing and fuselage drags differences >>>>>> I suspect that are several aerodynamic factors would have to be >>>>>> considered, especially given the the thermal core is dynamic. >>>>>> A question for modern designers perhaps, especially when all aviation >>>>>> design is a trade off >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> Richard Frawley >>>>>> [email protected] <mailto:[email protected]> >>>>>> We do not inherit the earth from our ancestors, we borrow it from our >>>>>> children >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> On 17 Jan 2019, at 9:43 am, Mike Borgelt < >>>>>>> [email protected] >>>>>>> <mailto:[email protected]>> wrote: >>>>>>> At 07:36 AM 1/17/2019, you wrote: >>>>>>>> >>>>>>>> Perhaps the more important question is how to you tell if one >>>>>>>> technique is better than another. What is a useful baseline? >>>>>>> >>>>>>> >>>>>>> >>>>>>> Climbing better than the other gliders is the test but what if >>>>>>> everybody is using the same less than optimum technique? >>>>>>> Mike >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>>> On 17 Jan 2019, at 7:16 am, Mike Borgelt < >>>>>>>> [email protected] >>>>>>>> <mailto:[email protected]>> wrote: >>>>>>>> >>>>>>>>> When circling in a thermal, do you >>>>>>>>> a) keep the string centered >>>>>>>>> b) fly with it pointing to the outside of the turn >>>>>>>>> c) why? >>>>>>>>> >>>>>>>>> Your technique may not be doing what you think it is. >>>>>>>>> Mike >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Borgelt Instruments - design & manufacture of quality soaring >>>>>>>>> instrumentation since 1978 >>>>>>>>> www.borgeltinstruments.com <http://www.borgeltinstruments.com/> >>>>>>>>> tel:Ã <tel:%C3%82> Ã 07 4635 5784Ã Ã Ã Ã Ã overseas: >>>>>>>>> int+61-7-4635 5784 >>>>>>>>> mob: 042835 5784Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã :Ã >>>>>>>>> int+61-42835 5784 >>>>>>>>> P O Box 4607, Toowoomba East, QLD 4350, Australia >>>>>>>>> _______________________________________________ >>>>>>>>> Aus-soaring mailing list >>>>>>>>> [email protected] >>>>>>>>> <mailto:[email protected]> >>>>>>>>> http://lists.base64.com.au/listinfo/aus-soaring >>>>>>>>> <http://lists.base64.com.au/listinfo/aus-soaring> >>>>>>>> _______________________________________________ Aus-soaring mailing >>>>>>>> list [email protected] >>>>>>>> <mailto:[email protected]> >>>>>>>> http://lists.base64.com.au/listinfo/aus-soaring >>>>>>>> <http://lists.base64.com.au/listinfo/aus-soaring> >>>>>>> Borgelt Instruments - design & manufacture of quality soaring >>>>>>> instrumentation since 1978 >>>>>>> www.borgeltinstruments.com <http://www.borgeltinstruments.com/> >>>>>>> tel:Ã <tel:%C3%82> Ã 07 4635 5784Ã Ã Ã Ã Ã overseas: >>>>>>> int+61-7-4635 5784 >>>>>>> mob: 042835 5784Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã :Ã >>>>>>> int+61-42835 5784 >>>>>>> P O Box 4607, Toowoomba East, QLD 4350, Australia >>>>>>> _______________________________________________ >>>>>>> Aus-soaring mailing list >>>>>>> [email protected] <mailto:[email protected]> >>>>>>> http://lists.base64.com.au/listinfo/aus-soaring >>>>>>> <http://lists.base64.com.au/listinfo/aus-soaring> >>>>>> _______________________________________________ Aus-soaring mailing list >>>>>> [email protected] <mailto:[email protected]> >>>>>> http://lists.base64.com.au/listinfo/aus-soaring >>>>>> <http://lists.base64.com.au/listinfo/aus-soaring> >>>>> Borgelt Instruments - design & manufacture of quality soaring >>>>> instrumentation since 1978 >>>>> www.borgeltinstruments.com <http://www.borgeltinstruments.com/> >>>>> tel:Ã <tel:%C3%82> Ã 07 4635 5784Ã Ã Ã Ã Ã overseas: >>>>> int+61-7-4635 5784 >>>>> mob: 042835 5784Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã Ã :Ã >>>>> int+61-42835 5784 >>>>> P O Box 4607, Toowoomba East, QLD 4350, Australia >>>>> _______________________________________________ >>>>> Aus-soaring mailing list >>>>> [email protected] <mailto:[email protected]> >>>>> http://lists.base64.com.au/listinfo/aus-soaring >>>>> <http://lists.base64.com.au/listinfo/aus-soaring> >>>>> >>>>> _______________________________________________ Aus-soaring mailing list >>>>> [email protected] <mailto:[email protected]> >>>>> http://lists.base64.com.au/listinfo/aus-soaring >>>>> <http://lists.base64.com.au/listinfo/aus-soaring> >>>> Borgelt Instruments - design & manufacture of quality soaring >>>> instrumentation since 1978 >>>> www.borgeltinstruments.com <http://www.borgeltinstruments.com/> >>>> tel: 07 4635 5784 overseas: int+61-7-4635 5784 >>>> mob: 042835 5784 : int+61-42835 5784 >>>> P O Box 4607, Toowoomba East, QLD 4350, Australia >>>> _______________________________________________ >>>> Aus-soaring mailing list >>>> [email protected] <mailto:[email protected]> >>>> http://lists.base64.com.au/listinfo/aus-soaring >>>> <http://lists.base64.com.au/listinfo/aus-soaring>_______________________________________________ >>> Aus-soaring mailing list >>> [email protected] <mailto:[email protected]> >>> http://lists.base64.com.au/listinfo/aus-soaring >>> <http://lists.base64.com.au/listinfo/aus-soaring> >> _______________________________________________ Aus-soaring mailing list >> [email protected] >> http://lists.base64.com.au/listinfo/aus-soaring >> <http://lists.base64.com.au/listinfo/aus-soaring>Borgelt Instruments - >> design & manufacture of quality soaring instrumentation since 1978 > www.borgeltinstruments.com > <http://www.borgeltinstruments.com/>tel: 07 4635 5784 overseas: > int+61-7-4635 5784 > mob: 042835 5784 : int+61-42835 5784 > P O Box 4607, Toowoomba East, QLD 4350, Australia > > _______________________________________________ > Aus-soaring mailing list > [email protected] > http://lists.base64.com.au/listinfo/aus-soaring
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