LoonyBob Posted February 1 Share Posted February 1 Re is speed x chord, J160 @ 56kt is same wing Re as T500 @37kt... 1 1 Link to comment Share on other sites More sharing options...
RFguy Posted February 1 Share Posted February 1 (edited) All the Jabiru owners I know who are also gilder pilots reckon their Jabiru's need spoilers ! Yeah on the '382, I noticed the 'inverse' behaviour at low Re. that airfoil is quite ''clever' . 'any idiot ' can make a nice high Re airfloil, lots of fluid inertia, a high CL / low Re airfoil is more finesse. Rod's J230 wing (and J170) seems to just keep on flying , right until the bitter end. There is VERY LITTLE perceptible increase in drag as it gets slow. It just keeps flying. Mind you, a strongly provoked climbing, 30 deg bank, uncoordinated full flapped power on stall putit into a immediate 180 deg spin entry, quite nose down facing the other way .... LOL I will always remember that one... My simultaneous awe of what happens so fast and associated expletive my instructor said was impressive......it was a good lesson is just how much an otherwise well behaved aircraft can bite if provoked Edited February 1 by RFguy 2 Link to comment Share on other sites More sharing options...
facthunter Posted February 1 Share Posted February 1 Re the 230, If it gets SLOW, hope you are low when on late approach. One well timed quick(er) flare in ground effect is all you've got . A lot of the reason they float is high engine idle speed plus being fast. Some who own them and familiar with them used to cut the engine just after the flare when landing on a short field. Nev 1 1 2 Link to comment Share on other sites More sharing options...
Markdun Posted February 3 Share Posted February 3 On 30/1/2024 at 10:49 PM, LoonyBob said: How many RAAus aircraft have much more than 10m wingspan or 12 square metres of wing? Bob, my Bert Sisler Cygnet SF2A comes close with a wing span of 9.1m and wing areas of 11.6m2; stall speed 34KCAS & cruise speed of 92KCAS, empty weight 250kg. Very similar to your D18. Also Jim Maupin tried hard to design a variable geometry wing when he was working on his Carbon Dragon foot launchable sailplane; in the end he concluded that trying to increase wing area (like a roll out sail on the trailing edge) just added too much weight, and he went for a fairly traditional 44’ tapered wing span with full span flaperons that reflexed for cruise. Stall speed was around 15 knots and Vne around 70. Max aero-tow speed was 40kts so towing was only possible with trikes or Bill Moyes/Bob Bailey’ ‘Dragonfly’. Design empty weight was off the Dragon is 75kg…the one I built was a bit more than that, so about 150kg TOW. It flew to the Jim’s specs. The Monett Moni motor glider also demonstrates the difficulties (or large compromises) of design getting low speed, low sink rate with good L/D at high speeds without variable geometry wing. The Moni has a Vso of 33kias, Vy 56, cruise at 90 & Vne of 130. TOW around 220kg. Yet L/D is only 20. The aircraft has a history of stall/spin fatalities ( I think attributed to some extent by pilots without gliding experience, an underpowered 25hp motor and the V tail) and Id expect any improvement in L/D by increasing wing span would not only make it slower but also increase its susceptibility to spins. I’m not sure why you’d want a 250kt RAA Aircraft…. Perhaps a better option instead of a T83 Thruster is a T38. 2 Link to comment Share on other sites More sharing options...
facthunter Posted February 4 Share Posted February 4 A giant step for MAN. Little planes are for fun. If you want to travel GO RPT.. IF you go high it seems SLOW. Compromise is the name of the game. 110 Kts is practical . Clean the plane up where you can and don't let it put on weight. Make it comfortable and controllable rather than stable. Stable is for free flight models. It's better if a plane stays where you put it when in turbulence. Nev 2 1 Link to comment Share on other sites More sharing options...
LoonyBob Posted February 6 Share Posted February 6 On 03/02/2024 at 9:07 PM, Markdun said: Bob, my Bert Sisler Cygnet SF2A comes close with a wing span of 9.1m and wing areas of 11.6m2; stall speed 34KCAS & cruise speed of 92KCAS, empty weight 250kg. Very similar to your D18. Also Jim Maupin tried hard to design a variable geometry wing when he was working on his Carbon Dragon foot launchable sailplane; in the end he concluded that trying to increase wing area (like a roll out sail on the trailing edge) just added too much weight, and he went for a fairly traditional 44’ tapered wing span with full span flaperons that reflexed for cruise. Stall speed was around 15 knots and Vne around 70. Max aero-tow speed was 40kts so towing was only possible with trikes or Bill Moyes/Bob Bailey’ ‘Dragonfly’. Design empty weight was off the Dragon is 75kg…the one I built was a bit more than that, so about 150kg TOW. It flew to the Jim’s specs. The Monett Moni motor glider also demonstrates the difficulties (or large compromises) of design getting low speed, low sink rate with good L/D at high speeds without variable geometry wing. The Moni has a Vso of 33kias, Vy 56, cruise at 90 & Vne of 130. TOW around 220kg. Yet L/D is only 20. The aircraft has a history of stall/spin fatalities ( I think attributed to some extent by pilots without gliding experience, an underpowered 25hp motor and the V tail) and Id expect any improvement in L/D by increasing wing span would not only make it slower but also increase its susceptibility to spins. I’m not sure why you’d want a 250kt RAA Aircraft…. Perhaps a better option instead of a T83 Thruster is a T38. Ye canna break the Laws of Physics, but it's fun to try!!! The Moni has a couple of design features to avoid it being too slippery, which of course impact the L/D; personally, I'd clean it up and fit airbrakes. Yes, V tails have two problems in an incipient or full spin, being (a) spanwise migration reducing the Cl, and (b) the control surfaces moving in opposition in yaw, and together in pitch... you can't get full down elevator with any rudder input. If the "conventional" spin recovery response doesn't work, cycling the elevators with anti-spin rudder is one of the options. In all honesty, if one is serious about going cross-country in an RAAus aircraft, large fuel capacity is more use than insane cruise speeds... 3 1 Link to comment Share on other sites More sharing options...
Kyle Communications Posted February 6 Author Share Posted February 6 Well as of the 9th of this month looks like Class 5 medical is a goer. This may well derail a lot of potential Group G converts. I know for me it will now allow me to re-engine my S-21 if I want or can afford to then run it in VH Experimental. The rules for maint and everything to do with licencing is the same as Group G. This then will make the fixed registration costs much cheaper....Food for thought Mark 2 Link to comment Share on other sites More sharing options...
BrendAn Posted February 6 Share Posted February 6 2 minutes ago, Kyle Communications said: Well as of the 9th of this month looks like Class 5 medical is a goer. This may well derail a lot of potential Group G converts. I know for me it will now allow me to re-engine my S-21 if I want or can afford to then run it in VH Experimental. The rules for maint and everything to do with licencing is the same as Group G. This then will make the fixed registration costs much cheaper....Food for thought Mark I was just going to ask but you did it for me. Why would ga people now go to group g . Link to comment Share on other sites More sharing options...
Thruster88 Posted February 6 Share Posted February 6 I have always said the two would be linked together. Can't have double standards in plain sight. 2 Link to comment Share on other sites More sharing options...
Kyle Communications Posted February 6 Author Share Posted February 6 My whole reason for going Group G was the medical. That now according to the CASA blurb can go out the window. I do not need to do my Austroads medical each year with my GP AND then go to a DAME to get a basic class 2 licence. This takes the DAME out of the situation and of course the cost. I have enough costs every year just to comply with my heavy vehicle licence. I maintain my heavy vehicle licence just for this reason so if I can drive a 64 tonne semi on any road allowed in Australia with my "special conditions" then I can certainly fly a aircraft with 2 people and under 2000kg. Every year I have a double appointment with my Dr to get the Austroads sign off then I have a cardiologist appointment every year with ECG every time. Every second visit there is a cardiac echo and every 4th year there is a stress test..and blood tests every 3 months for HB1AC .all this costs big bucks. With Class 5 well I can drop at least the double Austroads appointment and just do a std drivers licence medical each year with my normal doctor. In my case I KNOW what condition my heart is in and my body and endorine system is in...how many of you out there KNOW this about their own bodies.?..I may have had "some work done" but I KNOW exactly where I stand with my health...do you???? I can now re engine my S-21 with a engne bigger if I want to now and fly at the MTOW of 820kg instead of the Rotax MTOW of 727 kg. I have been thinging about this and think I may actually just do a turbo rotax which will give me between 135 and 145 hp..that will be heaps. The guy in melbourne does it to a std Rotax...not a big bore version like mine but its cheaper for me to do another complete overhaul of a out of time 912ULS and spend the 11K to do the turbo. I like this conversion because its a basic turbo conversion it does not have all the fancy electronic BS or the 915 and other after market engines. A local guy at my airfield has just put one in his Searey. We stuck a 4 blade Eprop on it and it has gone from 75 to 80 kts cruise to 96kts !!!!! at 5240 rpm. He still needs to further adjust the prop pitch which should make even more difference. The Searey is a bigger drag bucket than any savannah. If I did do this conversion I could still stay in Group G but would still be weight limited. The S-21 is HP limited for weight but that did not account for the higher HP Rotax engines. Mark 2 1 2 Link to comment Share on other sites More sharing options...
Blueadventures Posted February 6 Share Posted February 6 36 minutes ago, Kyle Communications said: Well as of the 9th of this month looks like Class 5 medical is a goer. This may well derail a lot of potential Group G converts. I know for me it will now allow me to re-engine my S-21 if I want or can afford to then run it in VH Experimental. The rules for maint and everything to do with licencing is the same as Group G. This then will make the fixed registration costs much cheaper....Food for thought Mark And CTA 1 Link to comment Share on other sites More sharing options...
Kyle Communications Posted February 6 Author Share Posted February 6 You can fly RAA into CTA if you aircraft is equipped with the right gear and you have the appropriate endorsements...apparently you always have been able to..the issue was of course it can be a RAA aircraft but you needed a RPL or a PPL to do it with the assosiated equipment on board 1 Link to comment Share on other sites More sharing options...
Blueadventures Posted February 6 Share Posted February 6 6 minutes ago, Kyle Communications said: You can fly RAA into CTA if you aircraft is equipped with the right gear and you have the appropriate endorsements...apparently you always have been able to..the issue was of course it can be a RAA aircraft but you needed a RPL or a PPL to do it with the assosiated equipment on board even 19 reg? Link to comment Share on other sites More sharing options...
Kyle Communications Posted February 6 Author Share Posted February 6 yes apparently so...I was told this just recently when I was discussing it with shall we say...someone who knows..and they make the rules 1 Link to comment Share on other sites More sharing options...
turboplanner Posted February 7 Share Posted February 7 4 hours ago, Kyle Communications said: yes apparently so...I was told this just recently when I was discussing it with shall we say...someone who knows..and they make the rules Can this person give you a definitive list of what aircraft are permitted,what equipment must be fitted and what degree of training is required? Somewhere like Camden would have what they use, but you can't afford a slip here if more people are to enter CTA. Link to comment Share on other sites More sharing options...
Kyle Communications Posted February 7 Author Share Posted February 7 They told me exactly what I just said above. IF you have all the required endorsements and qualifications and the aircraft is fitted out correctly with all the right gear you apparently are able to. It was a surprise to me as I was always told...by others I must adnit that you needed a "certified" aircraft ..like a factory built etc used for training Link to comment Share on other sites More sharing options...
RFguy Posted February 7 Share Posted February 7 14 hours ago, Kyle Communications said: In my case I KNOW what condition my heart is in and my body and endorine system is in...how many of you out there KNOW this about their own bodies.?..I may have had "some work done" but I KNOW exactly where I stand with my health...do you???? Mark, do you have Borg implants ? Link to comment Share on other sites More sharing options...
Kyle Communications Posted February 7 Author Share Posted February 7 hahahha I may as well have I think. But all that tech hasnt caught up with me yet I think its called paying for the sins of my youth 🙂 Link to comment Share on other sites More sharing options...
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