Flying a rocket at gross weight

[Houman]

Hi,

I have a short flight ( 1h ) scheduled soon and doing my W&B, I see that with 4 adults in the plane, I will be about 2 lbs short of my 2900 Gross weight and almost at the 3200 with fuel.

I usually am super super conservative on fuel and try to always have 1h of fuel reserve, according to my calculation I would need about 22 g of fuel, putting in 38g, so almost double to make sure I have enough in case I need to divert.

I'm wondering if other fellow Rocket owners have experience with flying at or near the gross weight and would you guys recommand to put less fuel to be farther off the 3200 lbs or keep the fuel for the added security...

Just wondering and if my thinking is wrong here, please let me know politely....

[chrisk]

I don't have a Rocket, but if the gross is 2900, it sounds like you should be making 2 trips.  Even with min fuel, you are 130 lbs over gross. 

 

Now if everyone is ok with being a test pilot, its really cold outside, at sea level, and a 7000 foot runway, I suspect it would fly at 3200 lbs.  The Rocket should have plenty of power.  But I'd also be real careful about landing over gross too.  The stall speed goes up.  The landing gear wasn't built for 3200 lbs.   --I don't know the laws in Canada, but I suspect this would violate a rule.  In the states it sure would.  Also should you crash, think about the article they would write about you being 300 lbs over gross....

[KSMooniac]

Rockets are 3200 lb gross, and should fly just fine at that weight or even heavier due to the ample power. The newest Mooneys are 3368 lbs for reference. Just know the plane will feel different, especially with aft CG, if you've never flown it at gross before. Longer takeoff, lower climb rate, higher approach speed, etc.

Sent from my VS985 4G using Tapatalk

[chrisk]

I just looked at the Rocket Engineering web site.  Yep, gross is 3200.  This should be reflected on the wight and balance.  I'd fill the tanks to gross and go.  Since your in Canada, it will probably leap off the runway compared to my 210HP M20K in 110 degree summer days.

[Houman]

Yeah I should have been more explicit about the limits of the rocket. The original plane ( Before conversion ) has a 2900 lbs gross weight limit, with the conversion, it is uped to 3200, but any weight exceeding 2900 lbs have to be fuel in the wings and not passenger or cargo..

So the way to calculate it ( as I understand my Rocket insert W&B figures ) is max of 2900 for plane and passanger zero fuel weight and 3200 lbs including fuel...

[Houman]

And yeah, the TSIO520 NB has ample power, as for the landing, I should be fine since I will be under my max landing weight ( well like 25 lbs under ) but still under...

Thanks for the heads up on the rolll and stall, I wonder if I should go near full power before rolling, I will be taking off from a 4000 feet runway, depending on the runway conditions.. usually with 2 people, I'm off way before half way, but at gross weight, if I can get the turbo boost earlier in the roll, it would be easier to take off I think.

[PMcClure]

If I am within POH W&B envelope, I would load and go. Even if I was a few lbs off in my calculation, Its better than trying to fly with minimal fuel. Running out of fuel probably kills more people than being 100lbs over. Not that I am suggesting to intentionally overload.  

[Houman]

If I am within POH W&B envelope, I would load and go. Even if I was a few lbs off in my calculation, Its better than trying to fly with minimal fuel. Running out of fuel probably kills more people than being 100lbs over. Not that I am suggesting to intentionally overload.

My thinking exactly....

[carusoam]

1) use the check lists...

2) W&B...

3) performance calculations...

4) hear the stall warning during the pre-flight

Just like every flight.

Passenger safety review may be different...

Best regards,

-a-

[MB65E]

I'd just do a normal take off and let it accelerate a bit longer than normal. I wouldn't reccomend a static take off with a left cross wind!! That got my attention in the "E" had a gust from the left that weathered vained me towards the bushes.

I was playing with the wind and seeing how quick I could get off...

I had to reduce power to keep it over the runway, the rudder was already on the floor.

Do the W&B, run the TO numbers, check Elevation, be smart, and Enjoy the airplane!

-Matt

[RocketAviator]

Not good response may be misinterpreted as recommended or suggested it is safe...

[RocketAviator]

Fly safe

[WardHolbrook]

Flying at max gross weight - within the W&B envelope - is a non-event. That would give me no pause whatsoever - as long as I had the takeoff and climb performance that your departure runways and terrain will require. (Why are we even having this discussion?) As far as partial fuel load operations go, it's a unfamiliar concept for many pilots whose experience is limited to small single engine piston-powered aircraft, but "fueling for the trip" is standard operating procedure for everything from larger light piston twins on up through the turboprops and jets. I too normally plan on 60 minutes worth of fuel on landing in EVERYTHING I'm flying. If there's a chance that I might need to divert to an alternate, then I'll carry even more. But in spite of the old joke about having too much fuel (...if you're on fire) there are times when you can have too much fuel on board - for example, if it causes you to depart over max gross takeoff weight.

 

The real question I think the OP is asking is "It it OK to takeoff over gross?" As we've seem, some guys will imply that it’s OK. This raises the question - Where do you draw the line? How much really is too much? A long time ago, most aircraft manufacturers adopted the principle of "loading flexibility” - in other words, Mooney, Piper, Cessna and Beech have made aircraft that provide us with one or two more seats than can be used if topped off with fuel or a couple of hundred pounds of fuel capacity that must remain unused it you’ve filled all of the seats. You can have it one way or the other, but you usually can’t have your cake and eat it too. (I’ve got PIC time in 105 different makes and models of aircraft, from gliders to jets, and I can count on one hand the number of them that you could honestly load up and go without regard to loading.) It's a legitimate approach; but history has shown us time and time again that there are many of us out there who have no idea of how the concept works. Silly pilots, many of us think that if we've got 4 seats we can top off, load up, and go. However, if you're willing to ignore the aircraft limitations, legalities, and insurance ramifications involved, you pretty much can because there is nothing magical about that max gross weight number – the airplane will continue to fly.

 

My recommendation is simple – just fly your airplane the way it was designed to be flown. Plan your flight the way the guys flying the jets do – while you’re doing your preflight planning just load your plane up with all of the passengers and baggage that you want to go with and then add enough fuel to bring the weight up to your max takeoff weight (for the given runway and conditions). If you’ve got enough fuel on board to fly non-stop to your destination plus your desired reserves (60 minutes minimum) you’re good to go, it you don’t, you plan a fuel stop. Simple.  

[chrisk]

Hi Ward,

After some clarification, I think the question is not about taking off above gross weight, but landing above gross weight.  The problem being the plane is at max gross landing wight with no fuel.  I believe the technically correct answer is:  you should include your reserve in the gross landing weight calculation.   

 

Now if I was presented with a choice of exceeding the gross landing weight, or having zero fuel reserve, I would choose to have extra fuel.  But of course since you get to make this choice on the ground, there is always the neither option.

[WardHolbrook]

[blushing from embarrassment...] Oops, you're right about the mis-read. But again, I just have to fall back on my experience and understanding. There are reasons for max landing weight limitations - especially if it is less than the max takeoff weight. You can choose to ignore any limitation, but at what point do you draw the line? Granted, there are some margins built into it, but when is too much too much? This is why it's so important to know your airplane. Some guys "ball park" or "conservatively estimate" things like fuel burn and fuel required to the point where they end up handicapping themselves unnecessarily and this is coming from the most conservative pilot you guys know - me. 

 

There is no reason why you shouldn't be able to calculate to within a gallon or two exactly how much fuel you'll burn on any given flight. If you're lazy like me, you'll want to use one of the free online flight planners like FltPlan.com or any other of the readily available computerized planning programs. Once you get those dialed in to the way you fly your airplane, they are bang on. (Coast-to-coast non-stop flights in our Falcon 900s are typically with in 2 minutes and 100 pounds of planned - a tiny fraction of 1%. The results in piston aircraft are equally impressive.) Once you know exactly how much fuel is called for then it's simply a matter of adding that 60 minute reserve to handle any unexpected vectors. Once you've got that figured out it's just a matter of math. You can either do it or you can't If you can't, you have to put less in the cabin or find alternate means of transportation. Simple. It may not be convenient, but it's still simple. 

[KSMooniac]

I think there is nothing mentioned about landing above gross weight... I think there is no limitation for the Rocket at 3200 lbs like there is with the newer planes that have a higher gross weight (3368) and a max landing weight (3200, I think!).  Rockets can take off and land at 3200 lbs I believe... I've only flown one a few times, though, and was far below 3200 so I didn't read as thoroughly as I should have.  

[WardHolbrook]

I've never flown a Rocket either, but if that's the case then what's the problem? It's all a matter of knowing YOUR airplane and flying it with in its operating envelope. 

[Houman]

Well there is a max landing weight, in my rocket it's 3050 lbs, so 150 lbs ( 25g) less than the max takeoff weight of 3200.

 

In no way or shape am I going over weight either takeoff or landing, I was just asking opinions on how the plane would fly near or at the max gross weight...

[KSMooniac]

Well there is a max landing weight, in my rocket it's 3050 lbs, so 150 lbs ( 25g) less than the max takeoff weight of 3200.

 

In no way or shape am I going over weight either takeoff or landing, I was just asking opinions on how the plane would fly near or at the max gross weight...

 

I stand corrected!  I thought there wasn't a max landing weight but couldn't remember for certain.

 

Run your W&B at takeoff and landing, and then go fly!  Just be mindful of the slightly diminished performance at 3200 lbs since you've never flown there before.  You might find the elevator control to be lighter with the aft cg too, so it will be easier to rotate on takeoff and flare at landing.  You might want to calculate a reference approach speed for your higher landing weight too.

[WardHolbrook]

I could give you the standard CFI response, but bottom line is that the airplane will fly just fine assuming that it's in the CG envelope. (I know you wouldn't fly it outside the envelope either.) It sounds like you haven't had much experience flying up near the edge of the CG envelope. If that's the case you ought to go buy a few bags of water softener salt and load it up and see how it goes on some of your lighter flights. Years ago, when I was checked out in a Baron 56TC (The original Rocket.  ), the CFI brought along several bags of salt to bring our weight up to the maximum allowable. Personally, I believe a checkout isn't complete until you've flown the aircraft and are comfortable with it at the edges of the envelope. But, as long as you're in the certified W&B envelope, you won't encounter any surprises.

 

Scott brings up a good point - your across the fence speed will be a bit higher at your max landing weight than it is at your normal landing weight - if you're using the proper speed at your normal landing weights. You'll want to add a little bit, but don't go crazy with it - it won't be much.

Edited December 12, 2014 by WardHolbrook

[KSMooniac]

When I did my Mooney checkout in my college club, my very experienced and Mooney-savvy CFI had me grab two friends to use as ballast so we could experience gross weight performance.  It was certainly a good idea!  We did some slow flight and stalls, then a few takeoffs & landings.  It is different, but not dangerous or anything... it is still a Mooney and your 305 hp will still provide more than ample performance.

[Jimhamilton]

Your limitations are your limitations. Exceed them and you risk safety, violation and insurance revocation. Is that clear.

[Hank]

I have no problem flying my C at gross weight. I found a snazzy Excel spreadsheet on line that also calculates balance. In the past, flying with four adult males limited me to 34 gallons (out of 52), or almost 4 hours. I was very careful when fueling, 17 gallons per side.

Takeoff was a little longer but not especially so. Climb was slower, making handling during the climb a little awkward, but not bad.

For landing, I always calculate speed on final based on gross weight. I roll wings level on final at 85 mph. At gross, I fly 75 mph on short final; for every 300 lbs below gross, I slow down another 5 mph. This number is easy to estimate on final. There is probably a similar relationship for your Rocket.

Regarding runway length, I was based on 3000' with trees at both ends for over six years. Never had a problem with 180 hp and a carb, even at gross, although when heavy it was not advisable to make a right turnout and cross the ridge, but rather turn crosswind and downwind THEN cross the ridgeline. Don't think your 305-hp machine will have a problem with 4000', and I'm shocked to hear that your normal ground roll is twice mine. Feet off the brakes, throttle forward. I know turbo pilots who hold brakes and stabilize power at 25" to check everything, then release brakes and push the rest of the throttle in.

[aviatoreb]

Well there is a max landing weight, in my rocket it's 3050 lbs, so 150 lbs ( 25g) less than the max takeoff weight of 3200.

 

In no way or shape am I going over weight either takeoff or landing, I was just asking opinions on how the plane would fly near or at the max gross weight...

 

My POH says 3200 max take off and 3083 max landing weight.  Remember, that landing weight is there because it reflects the engineered strength of your gear - don't push it and collapse your gear.  Climb performance remains fabulous at gross.

 

Stall speed does vary with weight - if I approach at the same speed when light and solo I would float forever compared to the same speed as when at gross. And worse when vice-versa.  I had an AOA indictor installed and it takes all guess work out of choosing a good approach speed since stall angle of attack is a constant.

[ahkahn]

If the POH/STC states 3200#, and you are at 3199#, I wouldn't think twice about it.  

 

Common sense (and a little business know-how) tells me that the engineers, test pilots, mechanics, insurance underwriters, attorneys, and FAA have built in some "buffer" room into that 3200#.  I wouldn't try it, but I guarantee it isn't a happy accident that the load factor limit just so happens to be at 3200# exact.  While not necessarily legal, I don't think that if you loaded the plane to 3201# it would spontaneously combust and mass hysteria and catastrophe would ensue.  Now where the breaking points, stress points, or whatever else could happen truly is, only the engineers and FAA knows.  I certainly don't want to be a test pilot and find out for myself.  I trust their numbers are very "safe" and conservative numbers. 

 

-Andrew