Max Baggage Weight 75 or 100 lbs?

[647jc]

Was working on a POH for my 9A and noticed on Van's website they list the maximum baggage weight for the RV9's as 75 lbs. All other POH's I've reviewed list it as 100 lbs. Was the limit changed from the original design? I vaguely remember something to that effect but would like to confirm.

Thanks...

 

[kentb]

Vans changed it.

It was 100lb when I started building my plane, but by the time I was finished it was changed to 75. I put 100lb in my W&B and did my flight testing with 100lb in the back.

Kent

 

[n2prise]

Baggage compartment load...

Like the man said, it is all about weight and balance. Do a spread sheed and start juggling the numbers. Heavy pilot, light passenger, light pilot solo, full fuel, minimum fuel. Watch the recommended C.G. range closely vs. the max gross weight. You can certify the gross anwhere within reason.

When Jon Johanson modified his RV-4 to become a world-rounding airplane, he had to get Van to sign off on a gross weight that is 30% over the recommended gross weight. That was because of the aviation regulations in Australia.

I did all the weight a balance numbers for my RV-9A with an O-320 with constant speed prop, and found I could still balance the airplane at 2000 pounds, which is 14% over the recommended gross weight of 1750 pounds. I flew the airplane to Oshkosh in 2006 loaded to the max with me at 240 pounds, another 180 pound pilot in the seat beside me, and 130 pounds of stuff in the back, stacked to the canopy, plus full fuel. It took off more like a Cessna 172, but cruised like an RV. If you go for a higher gross weight, you should also placard your airplane with two sets of V-speeds.

As for the ultimate load in the baggage area, not while flying, I have placed a board across the baggage floor and stood up there many times during construction, and after. I weigh in at 240 pounds.

 

[kentb]

A caution about structural strength.

Although the -9 is not an aerobatic design you need to keep in mine that the plane is designed to take a certain G load. I think that is it +5 -1. This would mean that if you are going to allow 100 lbs in the baggage area then you should at least be willing to place 500 lbs (on the ground) to test that it can hold it.

Kent

 

[647jc]

Agree, I'm not sure why Van lowered the 100 lb limit to 75. I suspect either structural or aft CG issues. I know with a basic O320 and Sensenich FP prop you can get into an aft CG situation pretty easy with 2 - 200 lb people and 100 lbs of baggage. Below 5 gallons of fuel you will be exceeding the aft CG. If the baggage limit is lowered to 75 lbs it's difficult to get into this situation. Anyway, I have no problem with a 75 lb limit, I just want to use the correct (Vans recomended) value in my POH.

Thanks for the input.

 

[Mel]

Typically when a designer limits baggage area weights, it's because of structural limitations. CG calculations are up to the pilot.
A 75lb. limit at 4.4gs (utility category) times 1.5 = 495lb. ultimate. This is the static load that the baggage compartment should hold.

 

[alpinelakespilot2000]

I have asked about this discrepency directly of Van's a couple times. Their unequivocal response both times was that it's merely a matter of c.g. People with wood fixed pitched props are probably going to be limited to 75#. People with metal constant speeds will probably be able to get away with 100#.

I have a heavy crush plate on my Catto prop to allow me to carry a full 100#.

If Van's has changed their tune on this, somebody please let me know.

 

[terrykohler]

Kent:
Trying to find where you got the +5g. My understanding was that the 1750 GW was the limit they used for testing to Normal Category specs (+3.8). Not sure if the Utility Category (+4.4) GW of 1650 came from testing or extrapolation. These numbers are important if anyone decides to practice steep turns above Va, as for example a bank angle near 70 degrees will result in loading approaching the Normal Category limit.
Terry

 

[N941WR]

Section 14, page 1, item 4:
Maximum Gross Weight: The maximum weight that the structure of the airplane can support at the 4.4G limit of the Utility Category. For the RV-9/9A, this weight is 1600 lbs.

G-LOAD TESTING
... The RV-9/9A structure had been designed to withstand utility design loads of +4.4/-1.8G at a utility gross weight of 1600 lbs...

MAXIMUM G-LOAD:... The RV-9/9A has a maximum G load of +4.4 and -1.8 at 1600 lbs...

MAXIMUM BAGGAGE WEIGHT
The maximum allowable baggage weight is determined by the structural limits of the baggage compartment floor, and is the maximum weight that can be carried in the baggage compartment under the most ideal conditions. For the RV-9/9A, the maximum permissible baggage limit is 100 lbs. This means that when C.G. limits and gross weight limits will permit, up to 100 lbs of baggage can be carried in the RV-9/9A baggage compartment. An example of this condition is a single pilot operating where this amount of baggage will not likely cause either the C.G. or the gross weight to exceed limits. With a single occupant, additional baggage can be carried in the passenger seat, but only if the C.G. and Gross Weight remained within limits, and if it is secured so that it cannot possibly interfere with the pilot's ability to operate the controls.

I could find nothing in that section of my builder's manual, dated 3/27/02, which talked about a 75 lb baggage limit.

Just remember, should you fly your airplane with an aft CG, it will get pitch sensitive.

It makes me wonder what the margins are at the higher gross weights some builders set.

 

[JHines]

Realistic Numbers?

Was working on a POH for my 9A and noticed on Van's website they list the maximum baggage weight for the RV9's as 75 lbs. All other POH's I've reviewed list it as 100 lbs. Was the limit changed from the original design? I vaguely remember something to that effect but would like to confirm.

Thanks...

Everything I've heard about Van's is that their numbers are pretty realistic. Perhaps they are quoting the 75 lbs. on the website as the max you might expect for W&B purposes when built "to Van's recommended spec" (O-320, wood prop, etc.), rather than the structural limit.

 

[alpinelakespilot2000]

I could find nothing in that section of my builder's manual, dated 3/27/02, which talked about a 75 lb baggage limit.

Just remember, should you fly your airplane with an aft CG, it will get pitch sensitive.

It makes me wonder what the margins are at the higher gross weights some builders set.

Thanks Bill. I knew 100# for baggage was written down in official paper form somewhere. I have a heavy Sabre crush plate, and a Meske slider tip-up conversion just to make sure I can carry two full backpacks + some misc. )

 

[kentb]

Terry, I made it up.

Kent:
Trying to find where you got the +5g. My understanding was that the 1750 GW was the limit they used for testing to Normal Category specs (+3.8). Not sure if the Utility Category (+4.4) GW of 1650 came from testing or extrapolation. These numbers are important if anyone decides to practice steep turns above Va, as for example a bank angle near 70 degrees will result in loading approaching the Normal Category limit.
Terry

My mind couldn't bring to the surface what the G rating should be. Mel is correct at 4.4G's. So the 100 lbs * 4.4 would be 440 lbs, not 500 lbs. I also forgot about the 1.5 for the safety factor so now we should put 660 lbs behind the seats! Be sure to prop the tail up and put some weight on the nose if you do this.

I did fly my plane with 100lb of lead shot in the baggage, but I don't think that I pulled 4.4g's while doing my testing. I guess that I didn't test the baggage correctly.

By the way, where can a guy get a negative 270 lbs to statically check the -1.8G value?

Kent