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Useful load concerns

bertschb

Well Known Member
Friend
I'm going to be a first time builder soon and recently learned about the ER fuel tanks offered by Sky Designs. I really like the idea of the added range these ER tanks would provide but I'm concerned about the reduction in useful load.

The problem is my passenger and I weight 410lbs combined. I believe this would put me at or near max passenger weight with full fuel with the standard tanks. The extended range tanks would add an additional ~108lbs of fuel and put me over gross weight if I had anything in the baggage compartment.

I don't really need four seats which is why I chose the RV-14 but now I'm thinking the RV-10 might be a better fit because of the higher useful load.

Thoughts?
 
ER Tanks

ER tanks make a lot more since in the 10 vs the 14. A 10 uses ~~ 50% more fuel per hour than the 14 yet has only 20% more fuel capacity (60 vs 50) My 14 has over 4 hours fuel taking into consideration min reserves and that's more than enough for my internal reserves. (And my wife's)

Attached is my 14's W&B. At 410 lbs. leaves little for baggage let alone the added weight of ER tanks plus fuel. Granted my 14 is a little piggy.
 

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Just because the tank capacity is there, doesn't mean it needs to be filled. Going solo leaves a lot more room for fuel.

There aren't many planes that can have full fuel and full seats. In fact it's almost unheard-of. (I flew a King Air that could take 120lbs payload with full fuel...that's 0 passengers)

Do the weight and balance before every flight. If that includes taking less than full fuel and adding a stop enroute, then so-be-it.

If 90% of the flying will include 410lbs of people, then maybe the ER tanks are pointless as the ER tank capacity can't be used. However, if there's going to be lots of long range solo flying, then the utilization of the extra tank capacity will be wonderful.

It's nice to have the fuel tank capacity when the load is smaller.
 
Hopefully Ken K. will "weigh" in on this question.

Ken produced a very detailed engineering analysis on the RV-10ER tanks, which included a justification for an increase in gross weight roughly equal to the amount of additional fuel added by the ER tanks. There were several caveats along with this included in this report. I have not seen an equivalent report for the RV-14, but I suspect it exists and there may be a similar statement regarding an increase in gross weight.

Not suggesting you do this without additional justification - but you are the manufacturer and you can set the gross weight wherever you choose. That being said, your DAR has final approval.
 
Hi Brian - as mentioned by Krea, the engineering analysis that went into the design of the RV-14ER tanks has been compiled into a report. Same scope and detail as went into the RV-10ER engineering report that he references.

As mentioned by David Z, you can vary your fuel load according to how much - or how little - your cabin load is. ER tanks give you more flexibility in that respect. Plus our ER tanks incorporate "tabs" for accurately determining partial fuel level.

As mentioned by dmattmul, you can also add weight during the build and end-up with an airplane that, while comfortable & nicely equipped, doesn't have the capability you had hoped for. BTW: our ER tanks will add 4.5 lb to your empty weight. No free lunch.

How much, how far, and how fast? Those are the three questions every aircraft purchaser has to ask. You are off to a good start by making sure you have chosen the best RV to fit your mission. Good job!
 
...Not suggesting you do this without additional justification - but you are the manufacturer and you can set the gross weight wherever you choose...

I've read this before and find this interesting. I would think Vans did the engineering to calculate the gross weight at 2,050lbs. My non-engineering mind tells me the RV-14 with it's short take off and excellent climb performance could handle 200lbs over gross during take off but then I'm very risk averse.

I really appreciate the feedback guys! I've never built a plane and I don't know anybody that has so my pee brain is struggling to figure out how I want to build this airplane.
 
Brian,

I suspect that a majority of the people on this forum have/had never built a plane before - so don’t let that discourage you from this endeavor.

I know this will sound like a broken record to some here - but the best build assist facility in the country has one of their locations just a few hours west of you in Eugene. I suggest that at the very least - you sign up for one of their Saturday fundamentals classes. It is likely they will have at least one RV-14 under construction there. You will learn a lot and can ask all the questions you want.

I always suggest that folks build their empennage there too, but not everyone can spare the two weeks and additional money to do this. If you can, it is one of the best things you can do (in my opinion) to get your skills well up the learning curve, learn what quality work looks like and to provide you with motivation to continue during the inevitable frustrating times.

I built my RV-7A there and my 10 at the Georgia location. I’m a big fan.

http://synergyair.com/all-oregon-classes/
 
Over gross operations

Most aircraft's can be flown safely within 10 % over MTOW as long as the CG is respected. This is normal when ferrying an aircraft on long flights.
But, it´s important to understand the implications.
You will be outside of the performance charts in the POH.
Doing this with a passenger and if there is an incident or worse may raise questions.

Good luck
 
I'm going to be a first time builder soon and recently learned about the ER fuel tanks offered by Sky Designs. I really like the idea of the added range these ER tanks would provide but I'm concerned about the reduction in useful load.

The problem is my passenger and I weight 410lbs combined. I believe this would put me at or near max passenger weight with full fuel with the standard tanks. The extended range tanks would add an additional ~108lbs of fuel and put me over gross weight if I had anything in the baggage compartment.

I don't really need four seats which is why I chose the RV-14 but now I'm thinking the RV-10 might be a better fit because of the higher useful load.

Thoughts?

I've flown 650nm a couple times and had between 15-18gal remaining in the standard RV-14A tanks. So, if you only fly ~700nm or less routinely, then you really don't need the extra expense and weight of the ER tanks. If you know a substantial number of missions will be >700nm in one shot and are single pilot, then sure, the ER tanks would definitely be worth it. However, with a passenger, it is rare for both you and s/he to have bladders that exceed 4.5hrs or so - a fuel stop with a biological break takes less than 20min.

_Alex
 
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However, with a passenger, it is rare for both you and s/he to have bladders that exceed 4.5hrs or so - a fuel stop with a biological break takes less than 20min.

_Alex

Wow, you must visit airports that employ line boys from Indy 500 races! I find that the time spent in the landing pattern, landing, taxiing, figuring out the self-serve fuel credit card reader, bathroom, taxi, checklist, takeoff and climb back to cruise ‘costs’ twice as much time. And if there’s food involved, it’s an hour minimum. I have balanced the injectors (-10) and routinely cruise lean of peak. For trips of a certain length (somewhat longer than 75% best power range) the door to door time is shorter by flying slower - because you can skip the fuel stop. And burn noticeably less gas to boot.
To the earlier poster: many -10’s are the exception to the rule. With full (standard) tanks I can carry 4 180 lb people and be below Vans’ 2700 lb gross.
To the OP: there are many options, many choices, when you build an RV. One thing that surprised me was how many friends and acquaintances wanted to ride with the wife and myself, which made the -10 the right choice for me. No aerobatics, of course, which may be a factor for you. Tim Olson, on this site from time to time, has built and flown both a -10 and a -14. He might offer you some insight.
 
The Possible

Jan Johanson- multiple RV4 record flights
RV9 around the world flight
Bill Harrelson:
lancair 4 nonstop from Guam to Jacksonville FL 7035 nm, 38 hours 40 minutes. 361 gallons fuel. Gross weight something over 7000#. current world record holder.
Max Conrad, Piper Twin Comanche, nonstop Capetown SA to St. Petersburg FL 800 gallons fuel. 58 hours.
Dick Rutan: Nonstop Anchorage AK to Grand Turk in the Long Eze.
 
...I suggest that at the very least - you sign up for one of their Saturday fundamentals classes.

Thanks for that suggestion! I signed up for the Fundamentals class on April 8th. The house I'm moving to next month has its own hangar so I'll build the plane in my hangar. If I lived in Eugene, I'd seriously consider building the empennage there but it's a 3+ hour drive each way.
 
As mentioned by David Z, you can vary your fuel load according to how much - or how little - your cabin load is. ER tanks give you more flexibility in that respect.

Thanks for the reply Ken. The flexibility of the additional fuel will probably be really convenient because there is no fuel at the airpark I'm moving to. So, I will have to fly somewhere just to refuel. Having an extra 18 gallons on board would cut down on these "fueling flights".

I know at least initially the majority of my flights will be solo as I build time. It would be really handy to have that extra fuel during that time and I would be under gross weight.
 
Personal tank

The flexibility of the additional fuel will probably be really convenient because there is no fuel at the airpark I'm moving to. So, I will have to fly somewhere just to refuel. Having an extra 18 gallons on board would cut down on these "fueling flights".

Moving to an airpark with no fuel you may want to consider installing a tank. My airpark does not have fuel but quite a few of us have our own 500 gallon tanks. The fuel company that supplies the local FBOs will deliver. No delivery fee and we end up paying about the same retail price as the nearby airports. Not all that expensive and you are going to save a lot of short "fueling flights" which waste fuel (extra takeoff and landing), personal time and very valuable engine time. Something to consider.
 
Thanks for that suggestion! I signed up for the Fundamentals class on April 8th. The house I'm moving to next month has its own hangar so I'll build the plane in my hangar. If I lived in Eugene, I'd seriously consider building the empennage there but it's a 3+ hour drive each way.

I live in Atlanta and still found the trip(s) to Eugene worth the time and expense.

If you aren't able to do that and assuming you are an EAA member - please take advantage of the EAA Technical Counselor program that is available. Hopefully, there is someone available in your area.

https://www.eaa.org/eaa/aircraft-bu...al-counselors/find-an-eaa-technical-counselor

There are a lot more abandoned projects than there are completed airplanes - so give yourself every advantage to build a high quality, finished airplane.
 
There are a lot more abandoned projects than there are completed airplanes - so give yourself every advantage to build a high quality, finished airplane.

I think I'll be OK. I'm retired so I have plenty of free time. I have the $ and my wife's backing to build and fully equip anything I want. I'm very particular so the build quality should be OK even though I suspect I'll need to buy a lot of replacement parts that I mess up since I'm a rookie builder. I'm kind of obsessed with researching things and there are tons of resources available to help there (VAF, EAA, YouTube, etc). And finally, I can walk out to my hangar to build and then taxi to the runway to fly. I have everything going for me except experience or good buddies with experience. That's huge but I can't change that.

Having said all of that, I may be looking at this with rose colored glasses and could be in way over my head. Time will tell!!!
 
Moving to an airpark with no fuel you may want to consider installing a tank.

Very interesting idea!!!! Maybe some of my neighbors have tanks. If not, maybe the HOA would consider installing one. Thanks for sharing this!
 
I think I'll be OK. I'm retired so I have plenty of free time. I have the $ and my wife's backing to build and fully equip anything I want. I'm very particular so the build quality should be OK even though I suspect I'll need to buy a lot of replacement parts that I mess up since I'm a rookie builder. I'm kind of obsessed with researching things and there are tons of resources available to help there (VAF, EAA, YouTube, etc). And finally, I can walk out to my hangar to build and then taxi to the runway to fly. I have everything going for me except experience or good buddies with experience. That's huge but I can't change that.

Having said all of that, I may be looking at this with rose colored glasses and could be in way over my head. Time will tell!!!

Having a spouse or partner that is on board is huge. I was fortunate as well and in fact, it was my spouse that encouraged me to build at Synergy.

If your spouse is willing, I would encourage you to sign her up for the Fundamentals class too. Having a bucking partner was one of the biggest benefits I found working at Synergy. It made a huge difference for me in the quality of the riveting. I know most builders rivet solo and some do beautiful work - but having another set of hands and eyes for quality control can make a huge impact.

Hope you get a lot out of the class. Talking with other builders, seeing all the projects under construction and getting my innumerable questions answered was a wonderful experience.
 
I really appreciate the feedback guys! I've never built a plane and I don't know anybody that has so my pee brain is struggling to figure out how I want to build this airplane.

I assure you, if you give your -14 a 6 hour range, your "pee brain" is the one that will become a limiting factor. :)
 
I assure you, if you give your -14 a 6 hour range, your "pee brain" is the one that will become a limiting factor. :)

Hah! For my use the ER tanks are more about not having to refuel as often rather than extended range for single flights. My wife and I do a lot of four hour drives but that's about the limit of our bladders.
 
Tim Olson, on this site from time to time, has built and flown both a -10 and a -14. He might offer you some insight.

I haven't read all the posts on this thread yet, but I'll summarize my opinion on the RV-14 vs RV-10 choice in this real simple summary.

If your goal *requires* aerobatics, then the RV-14 is a good option.
If your goal does NOT include aerobatics, what you really want is an RV-10. The RV-14 is an awesome airplane, however, for a multitude of reasons, the RV-10 is hands down the one plane I would not give up if I had to get rid of one of them. With my wife and I aboard, we are traveling in comfort with the equivalent of going cross country in a flying Chevy Suburban. I say that but from what we're finding, fuel economy wise, the RV-10 with it's parallel valve IO-540 flies very efficiently, unlike the truck. The fuel savings the RV-14 gives is not worth the lack of space you get when you're going x/c.

So it's really that simple. The only reason to choose the 14 over the 10 is aerobatics. Yes, it costs a little more to build a 10 too, but looking at the big picture, the difference is really not that large. If that cost difference is enough to force you into the RV-14, you should probably be delaying your build until you save more, or looking at regular GA aircraft to fly for a while.
 
Labor of love

The 10 will require another ~ 1000 hrs. to complete, even QB to QB. Going with ER tanks vs QB tanks add ~ 100 hrs. The fiberglass cabin top is a project to itself. Cost, present-day numbers ~ 50k delta. (Engine, prop, airframe, paint) As Tim points out added room a big plus but a 14 is no slouch in that category either. In the last month 2 well documented U tubers called it quits (Building 10's) with far less than 50% complete. Hourly cost is about 4 gals an hour delta so not a deal breaker. The 14's build documentation is superior especially for a first-time builder. Both great airframes.
 
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I'm going to be a first time builder soon and recently learned about the ER fuel tanks offered by Sky Designs. I really like the idea of the added range these ER tanks would provide but I'm concerned about the reduction in useful load.

The problem is my passenger and I weight 410lbs combined. I believe this would put me at or near max passenger weight with full fuel with the standard tanks. The extended range tanks would add an additional ~108lbs of fuel and put me over gross weight if I had anything in the baggage compartment.

I don't really need four seats which is why I chose the RV-14 but now I'm thinking the RV-10 might be a better fit because of the higher useful load.

Thoughts?

Do you really need extended range? I've been flying my RV-14A with my wife for over 200 hrs now and can rarely tolerate flying longer than 3-4 hours before stopping for a bathroom break and leg stretch. You can cover a lot of real estate in that time and be rewarded with finding some really interesting airports and meeting great people along the way. Your concerns are valid, particularly if your travels take you to high density altitude conditions. The RV-14 is a wonderful airplane with surprisingly ample storage in the rear. We just returned from a cross-country trip fully loaded with our 60lb yellow lab sitting in first class behind us and a great tailwind from Palm Springs to Amarillo non-stop. Can't beat that.
 
Tanks

I find it amusing that people think that if you have ER tanks you must fly longer legs…

It’s more about having options.
 
I'm not sure what is so amusing - that someone find the stock RV-14 perfectly suitable for their mission and needs?
 
Update-

I order Ken's ER fuel tanks today. I won't always fill the tanks but having the additional capacity will be a nice option when I need it. Thank you all for your input!
 
ER is not for everyone. With that said I agree with Bob on optionality regardless of mission.

I fly 90% of the time alone and my typical mission is 500-1000 miles so to me it makes sense. I am used to Disposable Urinal from the service and I would recommend using these for those long flights, it eliminates stops. Just my 2 knots.

Dan a box of these would be a nice add to the kit :)

O-RGI-030-2.jpg
 
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