Va and fantastic plastic

[RFguy]

I see there is alot of fantastic-plastic aircraft coming out of Europe.

 

you can have it all it seems, speed, low weight, full MTOW, low drag etc

 

But I can't help wondering, in comparison with the Jab airframe what sort of ultimate loads can be tolerated for the fantastic plastic when they are building them to be, - well - super fantastic plastic.

 

The jabs are "said to be'" designed for >= 2x spec load - IE up to +8G. But in all I read, every single Jab fail I can find , and I can find no record of any airframe failing anywhere , nor engine becoming detached......(until it collided with terrain).

 

What I see in the fantastic plastic is low Va numbers compared to Vcruise.. IE if its bumpy, you slow down alot..

 

The Jabs, (actually with the except of the J230, for whatever reason ???) Va at MTOW is all well above Vcruise .

 

But we don't hear too much either of too much fantastic plastic breaking up. Technology does stride ahead, although usually attempts to do more with less often lead to more brittle systems.

 

I have read more of aluminium breakups. I certainly know from ALuminium frames on road and mountain bicycles, they fail in catastrophic manner once they get a little old (due to the aluminium finite deformation fatigue life)

[pmccarthy]

Carbon fibre is amazing stuff. Watch Mike Patey's videos to see how it is laid up, how to strength test and so on, as part of his Scrappy build.

[onetrack]

Here is a relevant crashworthiness comparison of the various materials. Note that fire is not even considered in the article below.

Not only are the composite materials more flammable, the smoke from burning composite materials, is quite toxic.

 

https://journals.sagepub.com/doi/full/10.1177/1687814018794080

[skippydiesel]

Here is a relevant crashworthiness comparison of the various materials. Note that fire is not even considered in the article below.

Not only are the composite materials more flammable, the smoke from burning composite materials, is quite toxic.

 

https://journals.sagepub.com/doi/full/10.1177/1687814018794080

 

This is hardly the full picture - the most important safety feature of RAA level aircraft is (in most cases) very low stall speed. Issues of frame deformation and flammability/toxicity fall well below the ability of a pilot/crew to walk away from a 30 knot (or lower) crash. The low weight/inertia of most RAA aircraft also mean that impact energy, from a controlled crash landing, will be rapidly dissipated, reducing the chances of ruptured fuel lines/tanks and therefore fire.

 

On the topic of fire - while toxicity is an issue heat and smoke from whatever source is potentially fatal. The toxicity of the smoke (all smoke is toxic) is probably the least of your concerns in this scenario.

[Blueadventures]

I see there is alot of fantastic-plastic aircraft coming out of Europe.

 

you can have it all it seems, speed, low weight, full MTOW, low drag etc

 

But I can't help wondering, in comparison with the Jab airframe what sort of ultimate loads can be tolerated for the fantastic plastic when they are building them to be, - well - super fantastic plastic.

 

The jabs are "said to be'" designed for >= 2x spec load - IE up to +8G. But in all I read, every single Jab fail I can find , and I can find no record of any airframe failing anywhere , nor engine becoming detached......(until it collided with terrain).

 

What I see in the fantastic plastic is low Va numbers compared to Vcruise.. IE if its bumpy, you slow down alot..

 

The Jabs, (actually with the except of the J230, for whatever reason ???) Va at MTOW is all well above Vcruise .

 

But we don't hear too much either of too much fantastic plastic breaking up. Technology does stride ahead, although usually attempts to do more with less often lead to more brittle systems.

 

I have read more of aluminium breakups. I certainly know from ALuminium frames on road and mountain bicycles, they fail in catastrophic manner once they get a little old (due to the aluminium finite deformation fatigue life)

Worth considering that speed is not everything. When I was looking around Idid not want the 110 to 125 kt speed in a Jab as that brings with it the need of length to scrub off speed and therefore limits available private strips and country landing spots. I did email and had a call back from one of their aero designers Dan Moulder as I was asking if they had another wing option on the horizon that was draggy and offered the performance like the Foxbats and Savs etc. No was the answer and this was about 7 Years ago and they were busy with current matters at the time. I firmly believe there is a market place for such. Very good experienced Jab pilots can get into any PDF out of shortish strips. The Jab is a nice, forgiving and repairable fairly easily Fuse and wings etc. I finished up building a Nynja which I an absolutely happy with, and it did not need painting. I was also looking at the Sav S and that would have required painting which is a biggish task. In short perhaps look at anything that cruises at 85kts and easily lands in under 300 meters by low hour pilots, plus is true in responses.

[Old Koreelah]

...I firmly believe there is a market place for such. Very good experienced Jab pilots can get into any PDF out of shortish strips. The Jab is a nice, forgiving and repairable fairly easily Fuse and wings etc...

Too right, Bluey.

I'd love to see a J-170 with STOL ability; maybe a taildragger with longer legs and modified flying surfaces.

[Blueadventures]

Too right, Bluey.

I'd love to see a J-170 with STOL ability; maybe a taildragger with longer legs and modified flying surfaces.

Yep; now they have the nice 230 it could be a variant with a new wing design. There is I believe a market for such. hen they have time I guess. Next time I bump into Dan when he's in Mackay I'll hit him up. Plant another thought seed:cheezy grin:

[Kyle Communications]

You wont get Stiffy to approve that Mick.....You cant tell him anything...he does it his way or no way :)

[Blueadventures]

You wont get Stiffy to approve that Mick.....You cant tell him anything...he does it his way or no way :)

Good chance I'll be at the factory (just for a visit with some others on a fly south) first Monday in September and I'll politely let them know my thoughts if the opportunity presents.

[Kyle Communications]

Sue is nice enough and I think when Stiffy finally gets out of the business...she will make a good go of it. I think she has a more open mind to things. She gave me a complete tour of the whole place and was certainly open to a lot of ideas..even injection but the cost of certification was the issue. She has a good head on her shoulders

[RFguy]

Yes, Sue has been very helpful to me., also. J170STOL ? blown 2200 engine and tail dragging ? probably needs a different wing. off to cowra

[turboplanner]

But we don't hear too much either of too much fantastic plastic breaking up.

There's a photo of one floating around South Australia of one after a forced landing with the nose and engine completely snalled off and on the ground after the A pillars failed in tension.

The viiew is from the front and looks straight at the empty seats.

[Blueadventures]

Yes, Sue has been very helpful to me., also. J170STOL ? blown 2200 engine and tail dragging ? probably needs a different wing. off to cowra

Also can with kits give consideration to an alternate engine fit, especially in your farmilar and happy with the brand.

[facthunter]

Go fly yourself a taildragger. Jab then get back to us.. Nev

[skippydiesel]

Worth considering that speed is not everything. When I was looking around Idid not want the 110 to 125 kt speed in a Jab as that brings with it the need of length to scrub off speed and therefore limits available private strips and country landing spots. I did email and had a call back from one of their aero designers Dan Moulder as I was asking if they had another wing option on the horizon that was draggy and offered the performance like the Foxbats and Savs etc. No was the answer and this was about 7 Years ago and they were busy with current matters at the time. I firmly believe there is a market place for such. Very good experienced Jab pilots can get into any PDF out of shortish strips. The Jab is a nice, forgiving and repairable fairly easily Fuse and wings etc. I finished up building a Nynja which I an absolutely happy with, and it did not need painting. I was also looking at the Sav S and that would have required painting which is a biggish task. In short perhaps look at anything that cruises at 85kts and easily lands in under 300 meters by low hour pilots, plus is true in responses.

 

Hi Blueadventures - I have some concerns about, what I consider, to be your Jab/parochial view.

 

Don't get me wrong I am an admirer of the Jab fleet BUT your view of what is possible at both ends of the flight envelope is just incorrect.

 

There are RAA aircraft that can demonstrate a stall of 28 knots and a cruise of 135 knots (75% power/18L/h), same day, same engine, same load conditions, no tricks/mirrors. Take off on grass in under 100 m and land in not much more. Whats more you dont have to be a high time pilot to achieve this sort of performance (granted it helps).

 

Gone are the days when you had to make a choice between STOL & High Cruise capability - low operating costs/low performance and high cost/high performance. You can actually have it all - This capability has now been available for about 20 years or so and encompasses several aircraft types and manufacturers.

[Kyle Communications]

Whats the maximum rough air speed of it

[Downunder]

Do you know what a shill is Skippy?

[Blueadventures]

Hi Blueadventures - I have some concerns about, what I consider, to be your Jab/parochial view.

 

Don't get me wrong I am an admirer of the Jab fleet BUT your view of what is possible at both ends of the flight envelope is just incorrect.

 

There are RAA aircraft that can demonstrate a stall of 28 knots and a cruise of 135 knots (75% power/18L/h), same day, same engine, same load conditions, no tricks/mirrors. Take off on grass in under 100 m and land in not much more. Whats more you dont have to be a high time pilot to achieve this sort of performance (granted it helps).

 

Gone are the days when you had to make a choice between STOL & High Cruise capability - low operating costs/low performance and high cost/high performance. You can actually have it all - This capability has now been available for about 20 years or so and encompasses several aircraft types and manufacturers.

Skippy buy all means add your knowledge of the ability of other aitrcraft types and include thier MTOW, price and demonstrated performance in a reply.

 

Please re read my comment as I specifically spoke of the Jabiru performance in general. Therfore your comment is not warranted.

 

One you are most likely refering to is the Vixen -32; and I was not comparing performance with any other.

[Kenlsa]

I wonder where "STOL" starts and ends today.

If you look up what stol means in the early days it was anything less than 1500ft. A j3 or 3 with a Franklin or the real power house, the Conti 65 armstrong start were all classed as stol. But they really relied on the curvature of the earth to get airborne.

I would say that ANY of our RAAus planes will qualify. My SP 500 at MAUW gets of and over 50' at 400m. If I am solo and half fuel take off is 300m @ 50' and I can put it down in slightly less, tho that scares the Sturt Highway traffic a bit.

Strangely we seem to need to take off and land 2 to 3 times in that distance nowadays.

My advice is to look at the book specs, add a little bit and you will still be under the old stol.

BTW, a lot of pilots don't help themselves coz they build a heavy plane looking for that perfect paint finish then put every instrument they can think of that is worthy of IFR, then have backup instruments as well.

Keep it light, keep it simple, look outside- not at your wizbang panel and enjoy the ride.

Ken

[turboplanner]

I wonder where "STOL" starts and ends today.

If you look up what stol means in the early days it was anything less than 1500ft. A j3 or 3 with a Franklin or the real power house, the Conti 65 armstrong start were all classed as stol. But they really relied on the curvature of the earth to get airborne.

I would say that ANY of our RAAus planes will qualify. My SP 500 at MAUW gets of and over 50' at 400m. If I am solo and half fuel take off is 300m @ 50' and I can put it down in slightly less, tho that scares the Sturt Highway traffic a bit.

Strangely we seem to need to take off and land 2 to 3 times in that distance nowadays.

My advice is to look at the book specs, add a little bit and you will still be under the old stol.

BTW, a lot of pilots don't help themselves coz they build a heavy plane looking for that perfect paint finish then put every instrument they can think of that is worthy of IFR, then have backup instruments as well.

Keep it light, keep it simple, look outside- not at your wizbang panel and enjoy the ride.

Ken

STOL implies an above average power to weight ratio and an above average pilot who has received training in the pilot actions and reactions which may be required at any time.

I was sucked in by this STOL talk myself until I started training in a Jabiru LSA55 in crosswinds etc, i.e. normal flying operations where you may not be lined up in ideal conditions for a STOL landing.

For a start, the brakes in most RA aircraft have a lot less capacity than many GA aircraft.

Prior to that I'd decided to buy a Savannah kit and use the paddock next door for an airfield.

Then I started checking actual touchdown points vs the theoretical right on the start of the strip, and stopping within the manufacturer's specified distance. Sometimes it worked, sometimes it didn't, The slippery RA machines that perform so fast also need to land quite a bit faster than the stated stall speed in typical Melbourne off seasons.

So while I agree with most of what you say, I'd caution new pilots to get in the aircraft and fly in all conditions before judging something as a STOL, or more likely, an aircraft to buy that you can land anywhere.

I'm only raising this because we went through the same discussion on a series of long and interesting threads, and pretty soon after that the Sav owners went off in the direction of ripping out the slats and fitting DGs to get higher cruise speeds, so not point in another generation of flyers wasting their money because the old advice is next to impossible to find.

[Yenn]

Which planes are you speaking of Skippy?

High speed is not always the fastest way between two points. If you have to land to refuel your high speed plane, while the slower one keeps on, then the slow one could be faster. For short runs, say less than 100 milse speed makes little difference.

70 miles at 140 kts takes 30 min plus manouvering on ground, but at 100 kts it takes 42 mins plus the manouvering. Say 38 mins ompared to 46. Not so much really.

[Kenlsa]

A little while ago I was watching the end of a fly in and everyone was lined up and flying off back to their nests.

Watched a big balloon tyre Maule do a max take off, then watched all the Rec aircraft take off in a shorter distance! then a 180 did its stuff, but nothing spectacular. One of the best aircraft was an Auster and the grand champion was a humble Gazelle. These were average pilots I guess and I know the STOL people get serious but in the REAL word any RAAus plane will do. Its just that we have reduced the runway distance to qualify. I guess that if you own a Sav/FBat/701 you can have bragging rights to the shortest distance.

A few years ago in the US the 701 was involved in a large number of off field accidents................behind the drag curve and not enough excess power to drag its sorry arse out of it.

Ken

[facthunter]

Where your low cruising speed types don't do well is if you get stuck somewhere with high headwinds forecast for a while. Your range is seriously reduced and you can easily double your flight time. Nev

[skippydiesel]

Do you know what a shill is Skippy?

 

From Wikipedia - "an accomplice of a confidence trickster or swindler who poses as a genuine customer to entice or encourage others. "

 

I have answered your question. Now answer mine:

 

Are you suggesting that I am:

 

1. an accomplice of a confidence trickster

2. or swindler

3. posing as a genuine customer to entice.. others

 

Should your answear be yes to all or any of the above please give evidence of the same.

[skippydiesel]

Skippy buy all means add your knowledge of the ability of other aitrcraft types and include thier MTOW, price and demonstrated performance in a reply.

 

Please re read my comment as I specifically spoke of the Jabiru performance in general. Therfore your comment is not warranted.

 

One you are most likely refering to is the Vixen -32; and I was not comparing performance with any other.

 

Thank you for the invitation/opportunity Blueadventure.

 

First, as most/all of you know, I am in partnership with another enthusiastic pilot, with the aim of promoting and selling the ATEC aircraft range in Australia.

 

Having got that out of the way on to the list you have asked for:

 

My short list of aircraft that ALL fall within the RAA type and have a 600 kg Max take of weight.

 

Pipisteal Virus SW 121

erformance specifications can be found a://www.pipistrel-aircraft.com/aircraft/cruising/virus-sw-121/

The performance of this aircraft has been repeated verified by third party competition ( CAFE Foundation's Green Flight Challenge etc)

 

ATEC 321 Fayeta, 321 Faeta NG & 212 Solo (The 122 Zephyr is a bit slower at 124 knots cruise)

Performance specifications can be found at ATEC Aircraft - Czech manufacturer of light sports aircraft | ATEC Aircraft

Unfortunately I do not have independent verification of these aircraft performance BUT am willing to arrange a TIF so that you can verify, first hand, my claims

 

• The above aircraft all stall at around the 30 knot mark and can cruise in excess of 130 knots at 18L/h or less. All use Rotax 912 engines. With the exception of the ATEC 212 Solo there are flying aircraft in Au
  

 

I am sure there are other aircraft (that have very low stall, combined with high cruise) but non come to mind at this time.

 

Rerefence: "Please re read my comment as I specifically spoke of the Jabiru performance in general. Therfore your comment is not warranted."

 

The start of this conversation: "I see there is a lot of fantastic-plastic aircraft coming out of Europe. you can have it all it seems, speed, low weight, full MTOW, low drag etc" - seems to be a fairly broad question. You dont have to read or agree with my statements but to say they are "not warranted" is a bit harsh.