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Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 11:45 am
by drseti
Half Fast wrote: What does the calibration curve look like? Could it be that KIAS > KCAS at 45 knots?
Consider that a stall, by definition, occurs at high angle of attack. The pitot tube is attached to and parallel to the bottom of the wing. So, in a stall, the pitot tube is at a high angle of attack. That means the ram air pressure is across it. Not straight into it. So, in any airplane at stall attitude, the airspeed indicator always reads low. (That's why ASTM stall speed rules are based on KCAS, not KIAS.)

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 12:08 pm
by MrMorden
Wm.Ince wrote:Slap a Rotax 915 in that puppy and they'd have a winner.
I love the concept, but that's my problem with it. I can find no mention anywhere of the empty weight of the airplane, and I'd bet the reason is it sucks. The O-200D is a great engine, but it's too heavy for an LSA. I just shake my head sometimes when a company talks about making a dynamic, modern airplane, and then slaps an overweight 80 year old engine on it (yes, I realize the D model is updated, but still).

A 912iS (I think the 915iS would take it out of LSA) would reduce weight by about fifty pounds, and simplify operation (though maintenance might arguably be harder to find or more expensive).

Also: TAILDRAGGER.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 12:24 pm
by Warmi
The empty weight is 890 lbs.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 12:26 pm
by drseti
MrMorden wrote: A 912iS ... would reduce weight by about fifty pounds.
And a 912ULS would lower it by 60 pounds.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 5:35 pm
by chicagorandy
If the CFI is lean and mean, and the students are only lanky teenagers? Then I reckon this would make an acceptable trainer and still be able to carry more than 90 minutes of fuel. I saw an ad claiming 'room for two 200# fliers? Room yes, but I'm thinking you're not going to able to safely travel very far or long.

It would of course make for a dandy, roomy 1 person airplane.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 7:00 pm
by roger lee
With 2 x 200+ lb. pilots on board you really can't carry any fuel. It really needs to be trimmed down.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 7:21 pm
by drseti
Let's quantify that, Roger. 890 pounds empty wt and 1320 max gross leaves you 430 pounds useful load. With two 200 pound occupants, you get to carry 40 pounds of fuel. That's 6 2/3 gallons. The O200 burns 5.5/hour in cruise. So, a 1/2 hour legal reserve leaves you just under 3 gallons for a lesson. That would allow you a 32 minute flight lesson. And this is being marketed as a trainer??

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 7:31 pm
by Wm.Ince
drseti wrote:Let's quantify that, Roger. 890 pounds empty wt and 1320 max gross leaves you 430 pounds useful load. With two 200 pound occupants, you get to carry 40 pounds of fuel. That's 6 2/3 gallons. The O200 burns 5.5/hour in cruise. So, a 1/2 hour legal reserve leaves you just under 3 gallons for a lesson. That would allow you a 32 minute flight lesson. And this is being marketed as a trainer??
Gee . . . it's worse than I thought.
What are they thinking'?

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 8:08 pm
by Half Fast
Wm.Ince wrote:
drseti wrote:Let's quantify that, Roger. 890 pounds empty wt and 1320 max gross leaves you 430 pounds useful load. With two 200 pound occupants, you get to carry 40 pounds of fuel. That's 6 2/3 gallons. The O200 burns 5.5/hour in cruise. So, a 1/2 hour legal reserve leaves you just under 3 gallons for a lesson. That would allow you a 32 minute flight lesson. And this is being marketed as a trainer??
Gee . . . it's worse than I thought.
What are they thinking'?

It’s even worse.

Paul, I believe 430lbs useful load minus two 200lb occupants leaves 30 pounds for fuel, not 40. That’s only 5 gallons.

I guess you and your instructor do a lap around the pattern, full stop, refuel, another lap, full stop, refuel,..... I guess it’s great for instructors looking to build hours.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 8:37 pm
by drseti
Half Fast wrote: It’s even worse.

Paul, I believe 430lbs useful load minus two 200lb occupants leaves 30 pounds for fuel, not 40. That’s only 5 gallons.
You're right, Half. Thanks for catching my error. I just watched this week's AOPA Live segment about the Vashon. Tom Haines commented that, like all LSAs, this one is hampered by the arbitrary 1320 pound weight limit. I'm going to have to educate him on why "arbitrary" is the wrong choice of words, and maybe teach him how to compute kinetic energy!

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 9:07 pm
by Warmi
drseti wrote:
Half Fast wrote: It’s even worse.

Paul, I believe 430lbs useful load minus two 200lb occupants leaves 30 pounds for fuel, not 40. That’s only 5 gallons.
You're right, Half. Thanks for catching my error. I just watched this week's AOPA Live segment about the Vashon. Tom Haines commented that, like all LSAs, this one is hampered by the arbitrary 1320 pound weight limit. I'm going to have to educate him on why "arbitrary" is the wrong choice of words, and maybe teach him how to compute kinetic energy!
I actually think you both are right.
The 1320 limit is quite arbitrary in the sense that going over that limit doesn't really mean that much. The concept of increasing kinetic energy and its effect on survivability during off-airport landings ( or general mishaps ) is more appropriately defined as a range rather than a hard limit.
You would not consider off-airport landings in something Cessna 172 to be particularly more dangerous than similar landings in a typical LSA – as you move up the ladder in in terms of higher wing loadings and higher stall speeds you being to lower your odds significantly but it is still a range – definitely not a linear one but a range nonetheless.

Ultimately , if you are unlucky enough, you can die on a bicycle and, if you are lucky, you can survive an off-airport landing in a Lancair - everything in between is a range of probabilities.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 9:17 pm
by drseti
Warmi wrote: - everything in between is a range of probabilities.
True. However, once the physiology and safety experts have decided on what level of risk is to be consided acceptable (and ASTM Committee F37 invested considerable time and effort in making that determination), it behooves the engineers to design aircraft within the constraints they're given, and the pilots to operate within the resulting envelope. Violating or questioning those limitations is simply beyond Tom Haines' pay grade, and mine.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 10:40 pm
by HAPPYDAN
As the Ranger is being marketed as a trainer/backcountry flier, is there any advantage to even trying to certify this plane as LSA? The venerable but worn out Cessna 152 needs a sturdy, cost effective replacement, and it doesn't look like Cessna is going to produce one any time soon.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 10:53 pm
by Half Fast
HAPPYDAN wrote:As the Ranger is being marketed as a trainer/backcountry flier, is there any advantage to even trying to certify this plane as LSA? The venerable but worn out Cessna 152 needs a sturdy, cost effective replacement, and it doesn't look like Cessna is going to produce one any time soon.

Cost.

A standard cert, rather than to ASTM, would put it way above that $99k figure.

Re: Dynon founder is manufacturing a Light Sport Aircraft

Posted: Fri Mar 02, 2018 10:59 pm
by Warmi
They could go certified, of course, that’s only about $ 25 million or so ... or you go LSA for about $200 000.