Flight Design "Safety Box" & possible LSA Implications

[3Dreaming]

. . . "I think weight is a hurdle - but one that FD has overcome nicely." . . .

I have to slightly disagree, Eddie. The CTSW and CTLS passed over that hurdle, but IMHO, I think the CTLSi is too heavy for light sport. If all I wanted to carry was 20 gallons of fuel, I would have bought an RV-12.

Fuel injection and BRS recovery are good, but there is a penalty for having both or them. Weight.

I fly a fully loaded CTLSi (all glass cockpit, ADS-B, autopilot, fuel injected, solid state ignition system, BRS). Its empty weight is 830. That leaves 500 pounds for fuel and people.

Given my fuel burn is 4gph @120KTAS (conservative estimate, in practice I can get 3.6gph) I fly 5 hours on 20 gallons of gas. A distance of about 600 miles as the crow flies. That's 120lbs fuel weight. That leaves 380 pounds for people and goodies.

And realistically, the CTLSi is designed to fly at 1500 pounds gross (pre 912iS Sport upgrade) but that violates the 1320 rule for LSA in the USA. They do it in Europe.

My math says that it leaves 490, and not 500. 10 pounds doesn't sound like much, but it is 20 minutes flying time, an overnight bag, survival equipment, or a tool kit. I guess 10 pounds does make a difference.

[CTLSi]

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[Wm.Ince]

. . . "I fly 5 hours on 20 gallons of gas. A distance of about 600 miles as the crow flies. That's 120lbs fuel weight. That leaves 380 pounds for people and goodies." . . .

Except for a little better fuel economy, those numbers are about the same as an RV-12.

The RV-12 has one other advantage though . . . It's all aluminum. . . .
And . . . it flies better also.

Ever fly one?

[CTLSi]

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[Nomore767]

"Given my fuel burn is 4gph @120KTAS (conservative estimate, in practice I can get 3.6gph) I fly 5 hours on 20 gallons of gas. A distance of about 600 miles as the crow flies. That's 120lbs fuel weight. That leaves 380 pounds for people and goodies."

Hard to believe that this pilot burns 10lbs of fuel on 'warm-up and taxi'. That's what, 1.6 gallons?

If you burn 4gph in cruise you can't fly for 5 hours on 20 gals because there'd be no VFR reserve. Lets say 45 mins or 3gals for reserve, or round up to 4 gals to be conservative, that only leaves 16gallons or 4 hours flying time, of the 20 gals fuel load.

The weight remaining, given a 830lb empty weight, and 120lbs fuel, is 370lbs.. If you wanted to use the full fuel capacity of 32 gals, or 192lbs, there'd only be 308lbs remaining for pax and bags. You could go with one 'standard' person of 200-210lbs and carry bags but if there were 2 'standard' passengers then you'd have to compromise on fuel/bags etc. This is the dilemma of most LSAs, because of the arbitrary 1320lb weight limit, even though, in Europe, the planes fly at higher, more 'useful' weights. Still, this is with a lighter, composite, build material.

It's fortunate that the owner, in this case, has 2 'lightweight' passengers. Even so, with 270lbs of passengers, it only leaves 38lbs for bags, if you used full 32 gals fuel, and that is for a max weight airplane. If they were 'standard weight' passengers you'd have to reduce fuel significantly in order for both to go, carry bags. In this case 2 'standard weight' (200lb) passengers, full fuel and 35lbs of bags puts you 137lbs over gross. Okay in Europe, but not in USA.

As someone mentioned, WEIGHT, is the watchword of the LSA, particularly USEFUL load.. Especially the weight of the passengers! In that regard, the 'mission' is hugely important in regard to the airplane you select.

[drseti]

(I have fuel injection, solid state ignition, and a more stable tail).

Fuel injection is definitely a plus (though there are costs associated with it). I don't know much about the comparative stability of the different tail designs. I do know, however, that all Rotax 912 series engines (not just the injected ones) have solid state dual CDI ignition.

[Wm.Ince]

. . . "It's the same or better than your SW (I have fuel injection, solid state ignition, and a more stable tail)." . . .

I don't agree.
My documented empty weight is 748.51. That is 80 lbs. less than what you reported for your CT. For light sport aircraft, I think that is significant.
That withstanding, I am very aware of the great equipment in the CTLSi. But that equipment comes at a cost.

. . . "I have flown Zodiak low wings, and Samba low wings." . . .

You ignored my question. Have you ever flown an RV12?

[drseti]

This is the dilemma of most LSAs, because of the arbitrary 1320lb weight limit, even though, in Europe, the planes fly at higher, more 'useful' weights.

Howard, though this gets kicked around quite frequently on these forums, I must continue to emphasize that the US LSA weight limit is anything but arbitrary. It (along with the 45 KCAS stall speed limit) sets the kinetic energy to be dissipated in a landing or takeoff accident to around 100 kJoules, minimizing injury to occupants. That is about how much we humans can stand without sustaining fatal injuries. It was established as a safety limit, not an arbitrary limit. It's not about the airframe's structural integrity, so much as it is about your structural integrity.

I wish I had the same access to European accident data as I do to NTSB files in this country. I'd like to see what the fatal accident rate is in those European aircraft being flown at higher gross weights, as compared to the same aircraft operating under SLSA rules in the US. I'm interested in not just the accident rates (which are influenced by many other factors), but the percentage of accidents in otherwise identical aircraft that result in fatalities. I don't have that data, but I would strongly suspect that in Europe, the fatality rates are higher, since increasing weight increases kinetic energy to be dissipated -- not once, but three times: once for the change in mass, a second time for the increase in stall speed (since KE = in 1/2 mv^2), and a third time for the "squared" in mv^2.

Bottom line: the FAA does many things that are indeed arbitrary and capricious. LSA limits are not one of them. They are well thought out, though they only need be respected by those who value their lives, and those of their passengers.

[MovingOn]

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[Nomore767]

Paul,

In an effort to thwart thread creep and to avoid parsing words I bow to your superior knowledge!

On the other hand, 1320lbs is 'arbitrary' enough as far as we're all concerned, right? As in, it's a limit to which we must all adhere to and abide by.

[Wm.Ince]

Paul,

In an effort to thwart thread creep and to avoid parsing words I bow to your superior knowledge!

On the other hand, 1320lbs is 'arbitrary' enough as far as we're all concerned, right? As in, it's a limit to which we must all adhere to and abide by.

if it's good enough for a seaplane, then why isn't it good enough for the rest if us? . . . . .

[drseti]

if it's good enough for a seaplane, then why isn't it good enough for the rest if us? . . . . .

I guess the FAA doesn't value the lives of seaplane pilots as much as it does those of landplane pilots.

[CTLSi]

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[Nomore767]

None of you or your airplanes or your piloting skills can measure up to CTLSi. He is superior in all things. Just ask him.

This started with Ince mis-characterizing the CTLSi. Feeling defensive much?

Now that's funny, right there!!

[Wm.Ince]

. . . "Feeling defensive much?" . . .

That sounds a little like a provocation.
Do you really mean it that way?