Maybe I was not seeing average SR22's when I was looking at them, but full-fuel payloads of less than 400 lbs was not uncommon if AC was installed.

My main gripe with Cirrus, and any composite airframe for that matter, is that they are not lighter or stronger than the aluminum airframes they were supposed to make obsolete. Composite technology may work on the 787, but is did not deliver a lighter airframe at the same strength or a stronger airframe at the same weight.

Neal,

Not sure what you're adding to the G36 but by my math i have its useful load coming out to 689 with full tanks. Difference of 42lbs. to the cirrus

Neal, I think the 2,225 lb empyt weight is a marketing number as most of the airplanes I was looking at were higher. I don't recall the exact numbers but here is an example of a Turbo SR22 with an empty weight of 2,439 lbs:
http://www.controller.com/listingsdetai ... 167994.htm

We may be comparing apples and oranges here since this is a turbo but it definitely highlights your point about the 3400 gross weight issue. The 961 lbs of useful on this specific airplane translates into a full-fuel payload of 409 lbs. I will take your G36 with a 4000 lb gross over this airplane any day but you are correct that it's mostly due to a piece of paper saying it will not fall out of the sky at 4,000 lbs.

These composite airframes really do not create a lighter airplane. I believe the Columbia 400's are around 2500 lbs empty as well. I'm not sure if the 2700 lbs for G36 is for a TN's airplane but I will assume it is since my A36 would be about 2,650 if it were turbonormalized and had AC. An aluminum 6-place airplane is 200-250 lbs heavier than a 4-place composite airframe. I would be curious what the composite airplanes would weigh if they were built with aluminum. My guess is that they might actually be lighter.

I'm not in the fabricating business, but suspect the main driver for the composite airframes is the amount of labor required, not weight saved. Lots of rivets in a Bonanza, and it appears that some parts are individually hand-fitted.

Not only the labor savings, but the ability to create compound shapes that would be difficult in aluminum. For example the step in the wing lets the ailerons keep flying into a stall and makes for some really benign characteristics. Even to a lay person it seems obvious that a step wing shape would be difficult to reproduce in aluminum.

The above info comes from the Cirrus salesperson that I took the demo with.

Here are the weights I used:

http://www.hawkerbeechcraft.com/beechcr ... tions.aspx

3650 (max gross weight) minus 2700 (basic empty weight) = 950 useful load.
950 (useful load) minus 444 (74 gallons) = 506 max fuel payload.

I think I now see where you came up with 689. For some reason Beechcraft has 1133 listed as its useful load on its website. That may very well be true but the math didn't add up when I used their numbers of 3650 (max gross weight) and 2700 (basic operating weight). Can you figure out where their 1133 came from?

Interestingly enough, the basic empty weight (pre-addition of tip tanks) of the 2007 G36 that I fly is 2633lbs and it has air conditioning. So I am wondering why HBC is using 2700lbs as its empty weight since it doesn't say that AC is included (and normally AC wouldnt be included since its an option).

What are your thoughts?

-Neal

Chad,

If you are going to use the empty weight of a TN SR22 then you should use the empty weight of a TN G36 too, no? Also, we should leave tip tanks out of the discussion (especially when talking about the NA G36). I just found a 2006 TAT G36 for sale with an empty weight of 2733 (no tips). Of course, you do have the 4000lb GWI that comes with that added empty weight.

I also believe that it is unfair to penalize the SR22 for having an 18 gallon increase in fuel capacity, which translates to 108lbs of weight. If you loaded that 2439lb TN SR22 with 74 gallons of gas (which is what a non tip G36 holds) then you would have a useful load of 517lbs. Still nothing to write home about...I agree. It is unfortunate that the parachute degrades the max gross weight so much because we all know that the airplane can safely carry more weight (especially since it has 15 more horsepower than the IO550B).

But again, with that all said, I do believe that a tip tank TN G36 is the best single engine airplane available today (built within last few years). Period. Some will argue that a mid 70's renovated A36 with G500 is better since it is lighter but for simplicity sake, I am saying new generation planes built in last few years. I just don't like to see the Cirrus completely bashed for a shortcoming that isn't really so short (since it has a higher fuel capacity, which gives you more options...fuel versus payload).

Sidebar - the NA G36's (which is what I fly/manage) don't have the 4000lb GWI yet. Still patiently waiting!

-Neal

I fly a 2008 SR22 Turbo for a customer and have about a 100 hours in type. It has AC, Skywatch, and EVS. The empty weight is 2509 and the useful load is 891 pounds. We normally fill it to the tabs which is 60 gallons. Between the owner and myself, we weigh around 420 pounds, so that gives us 121 pounds for luggage if you include an extra 10 pounds for ramp weight. During the winter months you have to account for the TKS fluid and if you are climbing to altitude the weight of the oxygen. The limitation on increasing the Max Gross weight is the parachute. Although I am unwilling to fly the airplane over gross, it is done all the time with full fuel (92 gallons) and 4 adults.

Several of the 2008 G36 aircraft that I have checked without turbo have come from the factory with a useful load of 1061 lbs.

Things I prefer about the SR22 Turbo is the Perspective system and the dual Air Data and AHRS and the Keyboard entry of data. Cirrus does a better job of supporting the Garmin G1000 and integrated turbo engine support, EVS, WAAS (long before it was available on the G36), and SVT. During the summer, the AC can be left on during the takeoff and climb and nothing is extended into the airstream. The electrical system is more robust than the G36 system with two alternators, a 100 amp primary and a 70 amp secondary. The engine display page is much better than the G36 engine support.

I work as a MRB/Liaison Engineer, that repairs discrepancies with respect to Aluminum/Composite structure, and aluminum is much easier to work with and repair.
Composite is much more labor intensive as compared to aluminum sheet metal, ESPECIALLY from a reparability standpoint.

I respectfully disagree that a majority of the parts for the Cirrus skin could not have been done with more sheet metal. I am of the opinion that it could have been done less costly/higher quality. The efficiency/accuracy of profiles of stamped/hydro-formed, aluminum parts, equate to a less costly and much more quickly built product. What is less costly, a 2x-3x stamped process before trimming, or a prescribed lay-up pattern of cloth and couple hour pressurized cure at high temperatures. Aluminum, IMHO, aluminum is a more quality product, with respect to delamination in product. A discrepancy with aluminum is much more visually identifiable, where as composite requires Ultrasonic Inspection/X-Ray scanning to see what's really going on, inside.

From a weight standpoint, Engineering Factor of Safety is the key. F.S. is the amount of load a part is designed to carry, as compared to ultimate predicted load. There are a lot of unknowns with respect to the composite which requires a F.S. much higher than that of aluminum. Where an aluminum part may be designed to have a F.S. of 150% of ultimate load, a composite part may have a F.S. of 250% of ultimate predicted load, thus bringing weight up, considerably.

I personally wish they had made the Cirrus with more aluminum, especially for people that are concerned with the longevity/reparability of aircraft.

BTW, you can make composite parts made of Carbon Fiber/Fiberglass and bond aluminum to the part, as a wear part, and that is a little better, but not by much, as it only reduces repairs and not cost of repairs.

With full fuel, the average SR22 can carry nearly 700 pounds. That's a pretty big pilot.

Michael-

I'm not in a position to argue, that's what the Cirrus rep. told me and I won't be defending those guys positions any time soon.

It's interesting that most aircraft being designed today include composite work, regardless of size (GA or airliner). I'm sure their must be some reason why?

Alex

It's all good! I had a similar conversation with a Cirrus sales rep one evening that did not appreciate the efforts/outcomes of the TN system for Cirrus... I told him that, I would prefer a TNIO-550 F33 to carry around 4 people. Needless to say, we agreed to disagree!

Here's a link to an IHS white paper about composites in aerospace. Some good information here:
http://uk.ihs.com/NR/rdonlyres/AEF9A38E-56C3-4264-980C-D8D6980A4C84/0/444.pdf

I'm a liaison engineer on the government side, and Michael is right on with regards to the challenges of supporting composite aircraft/components. I don't know much about the Cirrus support network's philosophy, methods, or long-term plans, but keeping the fleet in good shape over time will be difficult and expensive.

I've refrained from commenting but only because I've told this story a million times on similar threads here in BT.

I owned half an SR22 for a year. I like everything about it except for the composite. It vibrated and rattled and got a yellow color to it from sitting in the sun.

I ended up buying a Bonanza.

If the SR22 were made of aluminum it would really be a great plane.

You'll never see 20 year old SR22's. I bought my Bo because I can fly it the rest of my life if I have to.

Jason,
You must have bought a real lemon if it "vibrated and rattled and got a yellow color to it from sitting in the sun". I've flown several of them; none vibrated and rattled or turned yellow.

The first SR22s were bought just over 10 years ago, and some SR20s are 12 years old. You think they'll all be grounded or fall apart within another 10 years?


Do you write things like this just to see what kind of reaction you can get out of some of us???