floats on a SLSA

[busted]

I like the msquared and quicksilver a/c. If I bought an SLSA and used it for instruction, assuming CFIS, could I put on floats for summer (no instruction, no sea plane cfi) and then take them back off and start instructing again?

[drseti]

Installing and removing floats would constitute a modification, which for an SLSA requires the written approval of the manufacturer (in the form of an LoA). I don't know offhand of any SLSA manufacturers who have issued an LoA for floats, but I suppose it's possible. That's a good question to ask before you buy.

[roger lee]

Flight Design has float planes. One usually shows up at Sun'n Fun, Oshkosh and the LSA Expo at Lockwood.

[CTLSi]

......

[busted]

Thanks, but I can't swing $161,000. Msquared says I could take the floats on and off (maybe he means I could have them taken off) and still you it for commerical use. As long as they aren't retractable. So it sounds like amphips are out.

[Merlinspop]

There are Legend Cubs, CubCrafters SportCubs and CarbonCubs on floats. I'm sure most of the latter are E-LSA though.

[Helen]

It's my understanding this if a manufacturer plans to put floats on the plane they either need to use part 23 certified floats or go through the ASTM certification process with the floats on. That's been the hang up on why there aren't more SLSAs with float options. The other option is to reregister the SLSA as and ELSA and then add floats but that takes it out of use for instruction.

The other factor to throw in there is that ASTM has a minimum useful load requirement for SLSAs. The FAA gives you about 100 pounds of extra gross weight to add floats but most amphibs weigh about 200lbs. So unless the plane already has ample useful load (the aforementioned Cubs do not) it won't meet the minimum useful load requirements to be an SLSA after you have floats.

To answer your question though, if the manufacturer of the plane has a set of floats that they approve for the plane and that don't take the plane out of the certification requirements (it needs to stay an SLSA not become and ELSA) you should be able to add an remove the floats.

Helen

[drseti]

ASTM has a minimum useful load requirement for SLSAs.

I had heard that, but not having access to the ASTM standard, I don't know what that weight is. Does anyone have that figure?

[roger lee]

Hi Paul,


That hurts my little feelings, you didn't remember.
I posted this April 17, 2012.

Here you go:

"It is 1/2 the Horse power, Rotax 912 is 100 HP so that equals 50. Plus the formula has a place for two 190 lb. pilot and passenger, that equals 380. Now add 50 + 380 = 430 lbs. That is the minimum for an LSA useful load."

[Merlinspop]

Hi Paul,


That hurts my little feelings, you didn't remember.
I posted this April 17, 2012.

Here you go:

"It is 1/2 the Horse power, Rotax 912 is 100 HP so that equals 50. Plus the formula has a place for two 190 lb. pilot and passenger, that equals 380. Now add 50 + 380 = 430 lbs. That is the minimum for an LSA useful load."

Isn't that 1/2 max continuous HP? Hence the Carbon Cub squeaking in.

[roger lee]

1/2 the mfg rated HP.

[3Dreaming]

Yes, it is max continuous HP.

[drseti]

That hurts my little feelings, you didn't remember.
I posted this April 17, 2012.

Heck, Roger, that was a year and a half ago. I don't even remember what I had for breakfast this morning!

In fact, as I posted, I did remember hearing (obviously from you, though I didn't recall that) about a useful load spec, just not the details. So, we know the number. But...

Somebody (sorry, don't remember who) posted the equation in metric units last night, along with the ASTM reference. Now that post seems to have been deleted. Could we have it back, please, so I can do the metric to imperial unit conversion myself? That's the only way I'm going to really understand it.

[Jim Stewart]

That hurts my little feelings, you didn't remember.
I posted this April 17, 2012.

Heck, Roger, that was a year and a half ago. I don't even remember what I had for breakfast this morning!

In fact, as I posted, I did remember hearing (obviously from you, though I didn't recall that) about a useful load spec, just not the details. So, we know the number. But...

Somebody (sorry, don't remember who) posted the equation in metric units last night, along with the ASTM reference. Now that post seems to have been deleted. Could we have it back, please, so I can do the metric to imperial unit conversion myself? That's the only way I'm going to really understand it.

That was me. I posted the formula out of the standard (there's two of them, one for a single seat and the other for a two seat aircraft). The standard uses weight in newtons (actually mass if I remember my physics correctly) and engine power in Kw. I wasn't doing the unit conversion right when I tried to use the formula on my aircraft and rather than leave something up that was misleading and not defensible, I deleted it. I figured out my error and the answer came out the same as Rogers. I'll try to post a screenshot of the actual formula sometime today.

[drseti]

Thanks, Jim - I'd like to be able to cite the source directly. As for the conversions:

To convert force in newtons to mass in kilograms, divide by the acceleration of gravity, which is 9.8 m/s^2. Then, to convert that force to weight in pounds at sea level, multiply by 2.2.

There are, if memory serves, 746 watts per HP, so to convert HP to kW, multiply by 0.746.