Safety (Lack of injury and death) is my prerequisite and priority

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Power required goes up with velocity cubed, so reducing overall drag 10% will shift cruise speed upwards only 2.15% max, but the increased weight means it is less than that.

It is my understanding that power required goes up with velocity squared, not cubed. I can't do symbols on this Mac, but I think you'll find the drag to power relationship is defined as: Drag D = drag coefficient Cd x density Ro x velocity squared divided by 2 x area A

Edit: just found the formula to copy - makes it tidier:

F = 0.5 Cd ρ A V2 (Where F is drag force)

Bruce

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If you're talking about being too high on final, that's another discussion.

This is what I had in mind, for an forced landing approach across obstacles (Safety). Normal landings per your post Nev, which I pretty much knew.

Examples of Bill's belly-flap and the Quickie belly-board are two hits showing/describing how these air-brakes work for anyone interested.

I will post to aircraft builders threads/boards from now on, as this is no longer to do with Bass Straight Crossing safety and thread followers are getting upset. I get the impression some pilots don't like left field hypotheticals and floating ideas much.

Thank-you to those who have helped me sort out my path

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It is my understanding that power required goes up with velocity squared, not cubed. I can't do symbols on this Mac, but I think you'll find the drag to power relationship is defined as: Drag D = drag coefficient Cd x density Ro x velocity squared divided by 2 x area A

Bruce

Thanks Bruce. Drag is squared. Power is cubed. Drag is force. Power is energy per unit time.

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The Australian Victa Airtourer has a flap that carries across beneath the fuselage. There are still plenty around of this 1960s manufacture.

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The Victa flap extension has been restricted (I think) as has the Cessna single series. The last notch of flap was very effective at getting it down. (steep approach angle.). One of the best in the business. Nev

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I can't believe this crap thread is still going!

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Well it’s BS trolling but a lot of good information came out.

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Well it’s BS trolling but a lot of good information came out.

I'm not trolling....If you want to fly across Bass Straight safely buy a bloody JET.

I wouldn't fly across in a single engine Aircraft as long as my freckle points South.

Why ask the question if you don't have the money to purchase an Aircraft fit for the job and if not aren't prepared to take the risk in a singe engine Aircraft ?

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I'm not trolling....If you want to fly across Bass Straight safely buy a bloody JET.

I wouldn't fly across in a single engine Aircraft as long as my freckle points South.

Why ask the question if you ain't got the money to purchase an Aircraft fit for the job and if not aren't prepared to take the risk in a singe engine Aircraft ?

I wasn’t referring to you Butch, I agree with you.

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I wasn’t referring to you Butch, I agree with you

Sorry mate.

Took it the wrong way !

Just think it's pointless...you either take the risk or you don't.

cheers

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I guess before you even take that risk path, you have to learn how to fly and get a licence/certificate.

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Discussing thing s increases awareness of the task and your overall concept of the situation. If you are not time constrained the more you do research the better the end result is likely to be.. How you learn to fly has a big effect on the final outcome re skills base. I've repeatedly said you don't do your ab initio flying many times. You do it once and some incorrect concepts may lurk there ready to emerge under pressure and ruin your day later if the.foundations aren't sound. .Nev

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Discussing thing s increases awareness of the task and your overall concept of the situation.

Thank you for your tolerant and informative posts that have helped me far beyond my original enquiry about risks associated with crossing Bass Straight.

There has been a lot of thread views, and strong responses, suggesting I am not the only one trying to calibrate the risks involved. A problem with the opinions offered is they vary from those who see little risk with RAA aircraft, right through to those who suggest buying a jet aircraft to do it.

I indicated my decision was made in post #83 and several times, so I don't get some narks.

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The Australian Victa Airtourer has a flap that carries across beneath the fuselage. There are still plenty around of this 1960s manufacture.

Thanks PM. A very interesting arrangement I had not noticed before: "This system also provides an air brake under the fuselage which provides lift at lower flap settings and increased drag at higher flap settings and can also be used as an aid for short field landings." The rapid decent on full stage flaps was noted in articles I found after reading your post! A very interesting implementation of the belly flap I was musing over, but probably should be on the 1965 Victa Airtourer 115 thread.

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If it do

Thanks PM. A very interesting arrangement I had not noticed before: "This system also provides an air brake under the fuselage which provides lift at lower flap settings and increased drag at higher flap settings and can also be used as an aid for short field landings." The rapid decent on full stage flaps was noted in articles I found after reading your post! A very interesting implementation of the belly flap I was musing over, but probably should be on the 1965 Victa Airtourer 115 thread.

If it does do what you say Jethro, I never managed to hold my tongue in the correct position to notice any advantage. I'd say I could land a Cherokee in a much shorter distance.

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My reference to steep approaches was more in respect of the Cessna models but the fact that last notch of flap is not used in either type makes the "commendably good" performance academic. You can't use it. The Fowler flap gives a big lift increase as well whereas the Victa, Piper and Beech planes are more % of drag with their "simple" flap...Nev

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If it does do what you say Jethro, I never managed to hold my tongue in the correct position to notice any advantage. I'd say I could land a Cherokee in a much shorter distance.

It was quoted direct from the link (click on it) TP! Clearly the manufacturers/designers thought it was worth providing. I was hoping some one who has flown a Victa Airtourer may care to comment. I suspect the changed flight characteristics and aircraft attitude of the final flaps stage is more difficult too handle, making it of little value for normal landings. I was musing the steeper glide angle may be helpful in forced landings over obstacles (not standard landings) in the hands of a pilot able to use it. If your reply refers to your own Victa Airtourer landing assessments then it is case closed Your comment about the Cherokee suggests the Airtourer needed a way to slow it up!? It could be that carrying the flaps under the fuselage improves flap efficiency and it has little to do with belly flap justification on other aircraft.

I agree with Nev it appears academic to most pilots, and this arcane theoretical discussion belongs on aircraft builders sites. I am learning all the time

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It was quoted direct from the link (click on it) TP!
Looked at it

I suspect the changed flight characteristics and aircraft attitude of the final flaps stage is more difficult too handle, making it of little value for normal landings.
You have to look at the overall aircraft profile; it's got a bulky fuselage, but excellent elevator and rudder control. I spent 28 hours in Victas and went through training in flapless, and shortfield landings, normal landings were full flap; a lot easier to fly than a Jab.

I was musing the steeper glide angle may be helpful in forced landings over obstacles (not standard landings) in the hands of a pilot able to use it.
You might be able to find some full flap glide angle data somewhere, but in my opinion visibility on shortfield landings was a bigger advantage than any noticeable glide angle. It stalls at 45 kts with full flap and we were trained at 50 for shortfields.

I

Your comment about the Cherokee suggests the Airtourer needed a way to slow it up!? It could be that carrying the flaps under the fuselage improves flap efficiency and it has little to do with belly flap justification on other aircraft.
No, no problem in slowing it up, just lift the nose like any other aircraft. What I was getting at was at normal approach with full flap, I can still land the heavier four place Cherokee in a shorter distance. The approach speeds are about the same, so when you take the feature in the Millicer design, it doesn't make much different aircraft to aircraft (it nevertheless still could make the Victa a better aircraft than it would have been without it).
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I think the Millicer design had airflow interference with the tailplane requiring the locking out of the last flap position . I never found the flap particularly effective on the Victa and I don't think it's a particularly good short field aircraft in average pilot's hands. Laminar flow wings also tend to drop their bundle rather abruptly particularly with small radius leading edges. (General comment.) Nev

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The last flap position was removed by CASA (their predecessor actually) via AD due aileron overbalance at low airspeed.

This later AD introduced springs into the aileron to increase the force required to deflect the aileron - the last flap position could then be reinstated but I am not aware of any which did. http://services.casa.gov.au/airworth/airwd/ADfiles/under/vat/VAT-034.pdf

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It was in the 60's I think or perhaps later. Thanks DJP. All flap was available when I flew them. Why would one use a lot of aileron at low speed , could be asked? Making a foolproof aeroplane is a big challenge. Also people will seek to justify their jobs if they have little to do. Nev

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I said I would post if I found any useful crash statistics, so here are some hot of the press LSA Accident Review: Nothing to Celebrate - Aviation Consumer Article, or the

if you don't want to look at the graphs so much

It relates USA LSA to "offer some perspective on LSAs compared to legacy stalwarts like the Cessna 150 and 172" and places the Jabiru aircraft about where I suspected they would fall (due to reported engine TBO IMHO). It still makes you wonder about the recent CASA actions.

It clearly indicates landing LSA is THE BIG issue (Why I have explored the belly flap/spoiler/airbrake, deciding it looks like training, not more gadgets, is a better route, though IMHO a foolproof way to drop lift (too late for other techniques) before a over hot landing becomes a bounce into a low level stall would be helpful).

It also makes clear that most pilots crashing LSA are well experienced! The need for thorough training on type is their main conclusion, and seems well founded. The final paragraph mentions Cirrus training, which may be part of their excellent record, not just their BRS as mentioned by @Jabba-who post #72

Hopefully others find it helpful calibrating their risk exposure. It suggests RAA, especially eRAA on average carry a significant risk increase over legacy GA.

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Certified aircraft are much more predictable than stuff built under less strict rules. The BUGS are removed from GA light aircraft pretty well by keeping well away from contraversial features and handling quirks. A C-172 should be extremely hard to crash but people still manage it. It's about the most docile and predictable plane out there. The Gazelle would be close to it in the RAA ranks but don't overspeed it and pull "G" at the same time.

. Flapless planes are not ruled out for reasonably short strips if you fly them appropriately. I reckon the Citabria 7 ECA I owned would get into most what people would call "short" strips . If a flap only knocks off 3 knots or so. it's not worth the complexity and weight, unless you Have to use it to meet the stall speed requirement .Very low wing loading planes are gust sensitive. The only way to pin a plane on the ground is pitch forward with a tailwheeler or have spoilers and that's not generally practical but gliders have and need them. They are not differential in that case. Differential is a rat's nest for UL's. I would not recommend flapperons either. I was a fan earlier on but they do require more flying skill than most appear to posses. and consequently they appear in the statistics more with near ground events.. Tubular steel tube is an excellent fuselage construction method but bordering on too heavy for the current weight limits. we are restricted to. Nev

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Why I have explored the belly flap/spoiler/airbrake, deciding it looks like training, not more gadgets, is a better route, though IMHO a foolproof way to drop lift (too late for other techniques) before a over hot landing becomes a bounce into a low level stall would be helpful).

Why worry.....Just do a go around !

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Why worry.....Just do a go around !

Jethro has virtually no flying experience, which he explained in Post 1, so he’s missing the compensations we would use without even thinking about it. On the other hand he has a prodigious appetite for reasearch which is going to do him no harm at all.