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RV-7A - Weight & Balance concerns. Is it the right plane for us?

O

Oliver

Well Known Member
Hello,

This is my first post - I live in Novi, Michigan, close to Detroit. My wife and I own a 0-300 powered 1966 Cessna 172. As we like to travel, we want to upgrade to a faster plane.

Intitially, we thought about getting a 182 or maybe an older Bonanza until another member of our EAA chapter showed us his RV-9A and offered a ride. While we both always liked the looks of RVs, none of us ever even sat in one. OK, now we want one. :eek: :rolleyes:
Except of that we could not take our bikes with us, a RV-7A would fit our mission perfectly, I could even do some light aerobatics with it. We also thought that a half-finished kit would be a great option, as I always wanted to build, but as I am afraid that I would not have the endurance to work on the project for 3 or 4 years.

Well, the more I investigate RV-7As, the clearer is becomes that we would most likely face W&B issues. My wife and I weigh, including clothes, headsets, a survival kit, something to drink, phones, etc. 400 lbs.. Based on the weight numbers, here in this forum, most finished planes seem to be around the max. empty weight Vans mentions on their website of 1,130 lbs..
This would leave us with an useful load of 670 lbs.. Minus our weight and full tanks (42 * 6 = 252 lbs.) we would have only 18 lbs. left for baggage.

It also appears as whether the CG tends to be very far aft. It actually seems to be so far aft, that reducing weight on the prop, the avionics or the crew and to instead put more baggage in the baggage compartment, would easily cause the CG to get out of the envelope.

I am now wondering, whether my concerns regarding the far aft CG are valid, whether something can be done about it and how much weight we could save with a fixed pitch instead of a CS prop? What else makes the planes heavy, besides of avionics?

Oliver
 
Of course swapping a CS to fixed pitch will move the cg back - just what you do not want. Have you looked at the -14? More expensive of course, but reports say it's easier to build than a -7. And more room.
 
Great questions, Oliver. I'm new to the RV world and wondering the same thing. I'm 215 lbs and have the same concerns ... looking forward to reading the replies.
 
Building a 7 close to you

I may not be able to give you great W&B answers, but I am building a 7 at Y47 in New Hudson. If you would like to see one in the build process, please let me know.

Marcus
 
mlang said:
I may not be able to give you great W&B answers, but I am building a 7 at Y47 in New Hudson. If you would like to see one in the build process, please let me know.

Marcus
Click to expand...

Ohhh - I was at New Hudson last month for two weeks (do you remember the red/white Cherokee parked outside about 80 yds east of the self-serve fuel pump?) I would have enjoyed seeing your build in process.

Have fun. Hope to catch you next time I'm in town.
 
I'm not sure what numbers you are running. My 7A came to 1,135 lbs and 77.9 in with a Hartzell CS prop. I can get two 200 lb people in, fill the baggage compartment (100 lbs) and the tanks and stay within the CG range (86.36 vs 84.92 in).

I increased my MTOW to 1,900 lbs and flight tested at that weight during phase I. The flight manual states the extra 100 lbs can only be carried as fuel. The fuel must be burnt prior to landing or a heavy landing inspection carried out. I also stick to paved strips in that configuration.

I prefer flying mine with some weight on and the CG aft. It is slightly faster in cruise and you can hold the nosewheel off forever. IMO you would have no problems with a suitably equipped RV7 as long as you are comfortable in it. As the others have said there is a lot more room in the RV14.
 
When we head to KOSH we are heavy with full fuel and bags. The issue really is the cg that moves aft in that config with only 5-10 gallons of fuel for landing. We just have to tell ourselves to lower our pitch control gains on landing.
 
Similar to Mr Talbert, My RV-7A with IO-360-M1B and Hartzell is 1100 lb empty (including cabin fire extenguisher) and has a forward biased CG such that if I follow the 100 lb baggage limit it is impossible to go out the rear GC limit.

At the risk of making general statements, it is my understanding that CGs for a 7A with CS prop will tend forward and CGs for a 7 with FP prop will tend rearward. Other combinations will be inbetween these two tendency limits.
 
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What adds weight?

Oliver:

Welcome Aboard! (Surprised I beat Mike- inside joke...). To your question, Almost everything adds weight.

Safety, comfort, convenience, and performance features, with very few exceptions, add complexity, build time, cost, and weight. Software is the only modification I know of with no weight effects.

A friend's 7 has great avionics, seats, upholstery, & other features which make it quiet, comfortable, easy to fly, and safe; my 9a has fewer amenities, is lighter, and safe.

You can build an RV 7 (3, 4, 6...10, 14) light if you wish, and many have. If you decide to build, suggest you consider the designer's thoughts:

"Van’s has always striven for "Total Performance"; the ability to do as many things well as possible. But all airplanes are compromises, and no matter how versatile, each is biased toward a particular 'mission.' "
 
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Be Careful.........

rwtalbot said:
I'm not sure what numbers you are running. My 7A came to 1,135 lbs and 77.9 in with a Hartzell CS prop. I can get two 200 lb people in, fill the baggage compartment (100 lbs) and the tanks and stay within the CG range (86.36 vs 84.92 in).
Click to expand...

with this scenario. Remember you won't be landing with full tanks. Try this loading with minimum fuel and make sure you are still within CG range.
 
Don't limit your decision

I am somewhat puzzled by your original post when it came to the weights you discussed. I have a 9A and there are, practically speaking, no scenarios that would move my CG out of balance either fore or aft. My 9A all up empty weight is 1117 lbs. In order to exceed the aft CG I would have to load 100 lbs in the baggage area, me in the pilot seat (255 lbs) a 120 lb passenger and less than 2 gallons of fuel. Not a situation I would ever allow. The only possible way I can move the CG too far forward would be if the plane were to somehow take off with full fuel and no humans or cargo on board. Again not going to happen. I can more easily exceed the gross weight than move the CG but still takes some doing. I can load me (255 lbs), a 200 lb passenger, and 100 lbs of baggage with full fuel and bust the gross. Again though, not really planning to do that anytime soon.

You stated you liked the RV9(A) but thought the weight issue would be a problem. The 7(A)s are great planes but so are the 9(A)s. I travel often with friends who fly RV7s. Down low they are faster and they can do aerobatics where I can't. However, for cross country flying I not only keep up with them speedwise but up high I even out perform them when it comes to cruise speed and fuel burn.

Make sure you can honestly analyze all the issues before coming to a conclusion of what you want. Don't let one issue (such as this weight/CG thing) make your decision for you. Evaluate all of the facts honestly then make the call.

Good luck with whatever you decide. Truthfully, you wont go wrong with any RV you choose.
 
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I have a -7A. My wife and I with a few bags are not 400lbs.:rolleyes: We fly regularly and are very pleased with RV and its performance. :D. Just saying...
 
Hello, Oliver,

If you build a -7, not a -7A, 100 pounds in the baggage area even with little fuel is do-able. The key is loading dense "stuff" forward of the center section spar in an airplane built with the mindset of keeping empty weight forward and most importantly off the long moment arm of the emp. Avoid gooing up the fuse and emp skins with primer, substitute a lighter-than-Van's tailwheel, and use the original design -8 rudder (1/2 pound lighter then the -9). Hang a 360 or a variant and a CS. Assure your painter understands the importance of minimal coating thickness.

I'm currently operating #5 of the -7s I've built. Even having substituted a Whirlwind for a Hartzell doesn't keep me from loading 100 pounds of bags. Tail draggers don't have the messy, intrusive main gear support structure under your knees; it's a flat floor from fuel selector to sidewall. On either side I can lash tents, water, ammo, etc, and, if it's a carby engine, the floor is flat from the selector to firewall, and here I can also lash down more heavy stuff. It's not so much that the weight is pushed forward on the teeter-totter, it's not in the baggage area behind the empty c.g. (I installed an EFII pump for FI, and designed it so the floor forward of the selector is still quite flat and useful.) Carrying more than 1800 pounds within c.g. is quite easy (Alaska rules!).

I can't answer how otherwise identical nose v. tail wheel airframes balance empty, but the A's gear structure is a deal killer to me in any case. A slider modified to tip up (easy) on a taildragger is the easiest RV to load. If you're considering a -14, consider the contortions of loading stiff, big objects, like an ice chest. To me it's utility is poor and it's a slow, fat -7 with a pricey engine.

I didn't express any opinions here, did I?

John Siebold
Boise, ID
 
You have the right idea to make sure that you get the right airplane for your mission. I flew a 182 for many years and carried all that stuff I really didn't need with me. As I grew older my "mission" changed and I was ok with 100 lbs. (most of the time). I do weigh my stuff when I am going to OSH or a similar long camping trip. The last thing you want to do is overload the airplane. You won't... you are obviously thinking about it now. I have 2 small bags for clothing and such that Amanda and I use that automatically keep our weight in the correct range. We usually haul our computers with us too. If you load the plane the same way every time you fly it helps eliminate the worry of being overloaded.

This guy has some really great excel sheets to wb calculations.
I only took a quick look at the 7a sheet and it is missing the wheel weights. They are 0. I'm sure he left it this way because each aircraft can have different weights depending on the engine/prop combo.

http://rv7-a.com/n447rv_documents.htm

So if you are gonna buy, just ask the seller for the wb doc and you can plug in the numbers and "play" with the numbers to figure out if it is gonna work for you.

I have a 6A with a heavy hartzel (7497 blades) 58 lbs prop out front.

So here are my numbers for my bird when it was born.

Nose wheel - 308
Left - 385
Right - 383

I thought this wb issue would be a big deal for me too, but I made the adjustment and really haven't missed the 182. I just flew non stop from dfw to south eastern colorado in 3:05 mins with 10 gallons left in the tanks. I also just came back from OSH camping gear and clothes. I buy heavy stuff (water, food) when I get to my destination.

One last thought. If you and your passenger are in the 250 lbs range, you can simply land every 2 hours and you have enough fuel on board to make your cg a non issue...at least with a heavy prop up front.

The vans community really are a remarkable and special group of people. Just ask Steve and lots of others just like him :)

Please join us.
 
Thank you very much for all your friendly and helpful responses, I now feel a lot more comfortable about a RV-7A again. Very much appreciated. :D
I apologize for the confusion caused by the 9A in my initial statement - the member of the our EAA chapter has a 9A, which we both like. As I am interested in aerobatics, I figured however that a 7A would be the better choice.

With the numbers, including the 1900 lbs gross weight, rwtalbot posted, W&B works out just fine, even in the extreme scenario with 2x 250 lbs guys, 100 lbs in the baggage compartment, only 27 gal. in the tanks and empty tanks when landing. In normal clothes, my wife and I are around 360 - 370 lbs, 400 lbs include stuff like something to drink, survival gear, headsets, etc..

I also looked at the W&B thread again and it appears as whether the CG of the 7 indeed is further aft than that of 7As, particularly if a light fixed pitch propeller is installed. Good for us, since my wife wants a nosedragger... :rolleyes:

I am familiar with the controversial discussion regarding whether the gross weight could / should be increased or not. I took away from it that the plane easily carries 1,900 lbs, as long as the CG stays within the given limits.
Some people were concerned about the landing gear. To define 1,900 lbs as the max. take off weight and 1,800 lbs as the maximum landing weight, as suggested by rwtalbot, would however be a conservative approach which should fix this issue. Frankly, though, 1,900 lbs are just 5.6% more than 1,800 lbs - I would guess that a firm arrival at 1,800 lbs would stress the landing gear significantly more than a normal landing at 1,900 lbs. :cool: And, unless I forgot to lock the car or there is a technical issue, I see no reason to fully load the plane with fuel and gear, only to land right after take off again.

Making the pilot and the passenger lighter is of course also always an option, past efforts showed however no permanent effect. I therefore don't want to count on it... :eek:

@mlang: I would love to see your project. We are pretty busy the next two weeks, after that we can meet anytime. I'll send you a pm, when our schedule relaxes. :)
 
Oliver said:
And, unless I forgot to lock the car or there is a technical issue, I see no reason to fully load the plane with fuel and gear, only to land right after take off again.
Click to expand...

Remember though - staying safer is a matter of building margin. So let's say to have just taken off at your 1900 lb weight, and smell smoke in eh cockpit. You decide that you really REALLY want to be on the ground right away, and pull it into a tight pattern. Tight enough that forget that the stall speed in a steep turn is also dependent on weight - stall/spin on the final turn.

Airplanes that have a lower landing weight than TO weight generally have a fuel dump capability. Thats to provide operational margin. Aircraft design limitations should not be defined by desire to "That looks about right".

Will it work? Sure - if everything goes right. But what if it doesn't? Everyone is free to decide for themselves of course - but everyone should evaluate the risk/trade for themselves as well. SOmeone will search this thread in the future for justification extend their Gross to 1950....

For two large people that want a two-seater to carry luggage and fuel cross-country? That's what the RV-14 is for.
 
Ironflight said:
[...] You decide that you really REALLY want to be on the ground right away, and pull it into a tight pattern. Tight enough that forget that the stall speed in a steep turn is also dependent on weight - stall/spin on the final turn.

[...]

Will it work? Sure - if everything goes right. But what if it doesn't? Everyone is free to decide for themselves of course - but everyone should evaluate the risk/trade for themselves as well.

[...]

For two large people that want a two-seater to carry luggage and fuel cross-country? That's what the RV-14 is for.
Click to expand...

Admittedly, I am new to experimentals, so please excuse my ignorance. I thought that during Phase I testing, the entire flight envelope, including the stall speed at different bank angles, will be tested and the POH created based on these results!?
Now, 'forgetting' is a different story, which is IMHO however not directly linked to an increased gross weight... ;)

The RV-14 would indeed be a nice two person travelling machine and might indeed be an option if we are able to find a project, as I am concerned that I might not have the patience to work on a kit for around 3 years. :eek:
 
Oliver said:
Hello,

This is my first post - I live in Novi, Michigan, close to Detroit. My wife and I own a 0-300 powered 1966 Cessna 172. As we like to travel, we want to upgrade to a faster plane.

Intitially, we thought about getting a 182 or maybe an older Bonanza until another member of our EAA chapter showed us his RV-9A and offered a ride. While we both always liked the looks of RVs, none of us ever even sat in one. OK, now we want one. :eek: :rolleyes:
Except of that we could not take our bikes with us, a RV-7A would fit our mission perfectly, I could even do some light aerobatics with it. We also thought that a half-finished kit would be a great option, as I always wanted to build, but as I am afraid that I would not have the endurance to work on the project for 3 or 4 years.

Well, the more I investigate RV-7As, the clearer is becomes that we would most likely face W&B issues. My wife and I weigh, including clothes, headsets, a survival kit, something to drink, phones, etc. 400 lbs.. Based on the weight numbers, here in this forum, most finished planes seem to be around the max. empty weight Vans mentions on their website of 1,130 lbs..
This would leave us with an useful load of 670 lbs.. Minus our weight and full tanks (42 * 6 = 252 lbs.) we would have only 18 lbs. left for baggage.

It also appears as whether the CG tends to be very far aft. It actually seems to be so far aft, that reducing weight on the prop, the avionics or the crew and to instead put more baggage in the baggage compartment, would easily cause the CG to get out of the envelope.

I am now wondering, whether my concerns regarding the far aft CG are valid, whether something can be done about it and how much weight we could save with a fixed pitch instead of a CS prop? What else makes the planes heavy, besides of avionics?

Oliver
Click to expand...

Google--- paul rosales rv 6A and read the travel stories and you will get good idea of the utility of the RV6-RV7 /A They have pictures of the luggage carried ect. There are many of us that travel across the US on month long vacations every year and think the RV6/7 is more than adequate. :) All you need to do is go to an RV fly in and see how many different sized people with lots of baggage fly in. or go to HB camping at OSH and look around. It?s a kick
 
Mel said:
with this scenario. Remember you won't be landing with full tanks. Try this loading with minimum fuel and make sure you are still within CG range.
Click to expand...

Like a number of others have mentioned, my plane with IO-360-M1B and CS prop came to 1165 and my wife and I weight together a bit over 400lb. We have often taken our dog (55lb) with some bags probably around 20Lb. We have landed with about 12G fuel left with no issues but I try not to push that.
 
Oliver said:
Admittedly, I am new to experimentals, so please excuse my ignorance. I thought that during Phase I testing, the entire flight envelope, including the stall speed at different bank angles, will be tested and the POH created based on these results!?
Now, 'forgetting' is a different story, which is IMHO however not directly linked to an increased gross weight... ;)

The RV-14 would indeed be a nice two person travelling machine and might indeed be an option if we are able to find a project, as I am concerned that I might not have the patience to work on a kit for around 3 years. :eek:
Click to expand...

Keep an eye, maybe search now, on the classifieds - I think Tom Martin just had his RV14 up for sale. You could not get a better start than that. The RV14 is a literally more than a decade ahead (of the 7 ) in design, and instructions. Don't get me wrong, I will love my 7 but I have seen the 14, and the 10 instructions. They are so much better than the 7. Years of experience at Vans pays off.
 
Oliver said:
Admittedly, I am new to experimentals, so please excuse my ignorance. I thought that during Phase I testing, the entire flight envelope, including the stall speed at different bank angles, will be tested and the POH created based on these results!?
o
Click to expand...

I would say that an average guy's 25 to 40 hours of Phase One "test" flying does not erase or override the designer's recommendations. IMHO...YMMV...
 
I am getting really unsettled, as I have received a number of messages, e-mails and responses in this thread, suggesting that I should never exceed the 1800 lbs, Van's mentions on their website.... :(
I don't see the danger in such a small increase of the gross weight, 1850 lbs would probably already suffice, but then again I want us to be safe and don't do anything stupid.

I also had a closer look at the RV-14. This certainly seems to be a nice plane, but another $20 - $30k, only to be able to haul maybe 60 lbs of camping gear or heavier baggage every once in a while, with which we would exceed the RV-7's gross weight by around 35 lb!? :confused:

I guess we'll have to seriously reconsider our options: RV-7A project, RV-14A QB-kit or to simply get a Cessna 182, what we were initially planning for. My wife isn't too excited about a retract, a v-tail Bonanza might however also be an option.
 
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Oliver said:
I am getting really unsettled, as I have received a number of messages, e-mails and responses in this thread, suggesting that I should never exceed the 1800 lbs, Van's mentions on their website.... :(
I don't see the danger in such a small increase of the gross weight, 1850 lbs would probably already suffice, but then again I want us to be safe and don't do anything stupid.

I also had a closer look at the RV-14. This certainly seems to be a nice plane, but another $20 - $30k, only to be able to haul maybe 60 lbs of camping gear or heavier baggage every once in a while, with which we would exceed the RV-7's gross weight by around 35 lb!? :confused:

I guess we'll have to seriously reconsider our options: RV-7A project, RV-14A QB-kit or to simply get a Cessna 182, what we were initially planning for. My wife isn't too excited about a retract, a v-tail Bonanza might however also be an option.
Click to expand...

It is not just the money, the newer kit will go much faster. Here is the post I remembered, it has a phone number. I might be the answer to all of your wants. http://www.vansairforce.com/community/showthread.php?t=127724 A discussion with Tom can not hurt.
 
Oliver, the problem with the approach of "I'll test it in Phase 1, and then I'll always remember to fly it in those limits" is that you are relying on the pilot never making a mistake later on. In the risk management business, we call that relying on an Operational Control of risk - and while that might be a good approach if there is one additional backup to a pilot mistake, it certainly puts you way out there on the risk meter if a single (simple) failure can be fatal. Heavy AND aft CG is a good recipe for pilot overcontrol.

I agree with you that you might want to look at other options, no matter where that search leads - even away from RV's. Pick the airplane that fits your requirements.
 
Oliver,

Take a deep breath, relax. With this kind of money at stake, you need to take your time, think thru and check out all options (even non-RV!).
Have you and yours sat in a -7? in the -14? There is no question the -14 is more comfortable, but only you or, especially, your wife, can say how much more or if the -7 is too cramped to be tolerable.
As a long time 182 owner I will say it is a great airplane, and maybe that is what you want. Compared to an RV it is slow, and burns a lot of gas. But if you only take short trips that won't matter. Of course it won't do aerobatics.
Building is not for everyone, and if that's not you, that's okay. It does rule out the -14 in the near term as none are built and for sale yet.
 
Landing Weight

Ironflight said:
Remember though - staying safer is a matter of building margin. So let's say to have just taken off at your 1900 lb weight, and smell smoke in eh cockpit. You decide that you really REALLY want to be on the ground right away, and pull it into a tight pattern. Tight enough that forget that the stall speed in a steep turn is also dependent on weight - stall/spin on the final turn.

Airplanes that have a lower landing weight than TO weight generally have a fuel dump capability. Thats to provide operational margin. Aircraft design limitations should not be defined by desire to "That looks about right".

Will it work? Sure - if everything goes right. But what if it doesn't? Everyone is free to decide for themselves of course - but everyone should evaluate the risk/trade for themselves as well. SOmeone will search this thread in the future for justification extend their Gross to 1950....

For two large people that want a two-seater to carry luggage and fuel cross-country? That's what the RV-14 is for.
Click to expand...

I have to disagree with the statement about fuel dump. I have flown most of the popular light twins and turboprops. I don't remember a single one that has fuel dump. Some approve landing at max takeoff weight, many do not. A company that I worked for, long before I worked there, allegedly operated with total disregard for landing weight. They did a lot of very short positioning flights where the landings were well in excess of the maximum approved landing weight.
On one fairly rare model of the DC9, the airplane was certified without a fuel dump system. Landing weight was 102,000 and takeoff 114,000. A return after takeoff with overweight landing required a fairly simple overweight landing inspection.
 
Phase One

Oliver said:
Admittedly, I am new to experimentals, so please excuse my ignorance. I thought that during Phase I testing, the entire flight envelope, including the stall speed at different bank angles, will be tested and the POH created based on these results!?
Now, 'forgetting' is a different story, which is IMHO however not directly linked to an increased gross weight... ;)

The RV-14 would indeed be a nice two person travelling machine and might indeed be an option if we are able to find a project, as I am concerned that I might not have the patience to work on a kit for around 3 years. :eek:
Click to expand...

The new format for ops limitations require only Vso, Vx, Vy and the weight and cg where these numbers were obtained. There is a paragraph about "throughout the normal operating speed range" or words to that effect, which would IMPLY testing to Vne, among other things.
 
Gross Weight

If you look at the history of most US light aircraft that had a long production run, in most cases you will find significant gross weight increases over the years. In many cases there were no structural changes for the weight increases.
A few examples:
Piper Aztec 4800 to 5200 gross
Piper Commanche 2800 original 250 to 3100 for 260
Bonanzas had a gross weight increase nearly every model, sometimes there were structural changes sometimes not.
DC3's in WWII were routinely flown 30% above the original civilian weight.
 
Baggage

My 7a is not finished but I'm trying to keep her light. I carry around enough already.:eek:
Sweetie and I used to travel a lot on our Goldwing. Pretty limited on baggage so we learned.
A few times we shipped stuff to the destination and shipped stuff back.
So basically we will learn to live within the limits of our airplane.
Just a suggestion.
 
jrs14855 said:
The new format for ops limitations require only Vso, Vx, Vy and the weight and cg where these numbers were obtained. There is a paragraph about "throughout the normal operating speed range" or words to that effect, which would IMPLY testing to Vne, among other things.
Click to expand...

Gonna have to jump in here. You must test the aircraft "throughout the aircraft's normal range of speeds and throughout all maneuvers to be executed."

 Vso, Vx, Vy, and the weight and CG location at which they were obtained are the only numbers required to be listed. That does NOT mean that these are the only numbers that require testing.
 
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Ironflight said:
[...] In the risk management business, we call that relying on an Operational Control of risk - and while that might be a good approach if there is one additional backup to a pilot mistake, it certainly puts you way out there on the risk meter if a single (simple) failure can be fatal. Heavy AND aft CG is a good recipe for pilot overcontrol. [...]
Click to expand...

The effects of a changed gross weight on the stall speed are predictable, I could however indeed imagine that a stall develops differently at a significantly increased weight, even if the CG is within the originally defined limits.
In the case we are discussing here, an increase of the gross weight from 1,800 lbs to 1,900 lbs would raise the stall speed only from 58 to 59.6 mph: √(1,900 / 1,800) * old stall speed of 58 mph).
I consider a difference of 1.6 mph as pretty much negligible. Even in a 45° bank, the stall speed would increase by still only 1.9 mph. The difference between the stall speeds at solo and gross weight, Van's lists on their website, is 7 mph and should therefore be of much more concern if you are worried that pilots might forget these numbers and if you think that the exact value is important in an emergency situation.

The POH section of this website hosts the POH for N2447A. According to this POH, best glide with flaps down is 80 mph. Assuming the pilot sticks to this airspeed, despite of the of the aircraft's higher weight, the margin between his airspeed and a stall would be reduced from 22 mph to 20.4 mph - I would think that this is irrelevant in a real world scenario.

Btw.: I also opened a few other POHs. None contained any information in this regards at all. Even the latest Cessna 172SP POH only lists information for max. gross and at max. aft. CG. ;)


BobTurner said:
[...] Have you and yours sat in a -7? in the -14? There is no question the -14 is more comfortable, but only you or, especially, your wife, can say how much more or if the -7 is too cramped to be tolerable.
As a long time 182 owner I will say it is a great airplane, and maybe that is what you want. [...]
Click to expand...

Neither of us sat in a 7A, I thought however that the cockpit of a 9A is almost identical!? The width is pretty much the same as in our 172, which is fine, even on longer flights.

I also spoke with my wife tonight, she was very specific: Either a half finished RV-7A project or a 182, with a strong preference for the RV-7A. We also agreed that building would be fun, but that our first project should be limited to 1 - 1.5 years. We therefore neither want a finished plane, nor start from scratch.

We will also consult the technical adviser at our EAA chapter about an increase of the gross weight from 1,800 to 1,850 or 1,900 lbs..
 
Oliver said:
I am getting really unsettled, as I have received a number of messages, e-mails and responses in this thread, suggesting that I should never exceed the 1800 lbs, Van's mentions on their website...
Click to expand...

If I knew you personally, I would do as others have done via this site: sit down with you for a private, professional, pointed discussion to consider this (currently) four page discussion; I'm posting this publicly both for you and future readers:

-You have received advice from a number of separate sources, publicly and privately, recommending against exceeding the designer's gross weight.
-You have received a number of recommendations for alternate solutions.
-You are not qualified to assess the design, or the risk.
-Your actions have significant implications for you & your wife; your insurance carrier; future owners or operators of an airplane; and this community.

Please do not exceed designed gross weight.
 
Aerobatic

Something else to consider in the decision.
Aerobatic gross is 1,600 lbs.
You may want to do the math specific to your situation.
 
jrs14855 said:
If you look at the history of most US light aircraft that had a long production run, in most cases you will find significant gross weight increases over the years. In many cases there were no structural changes for the weight increases.
Click to expand...
All of these increases would have been backed up with engineering calculations to show that they were valid... Not a group of people on the internet saying "i've done this lots of times and it was fine..."
 
PaigeHoffart said:
http://www.vansairforce.com/community/showthread.php?t=1158
Click to expand...

I am aware of this and other discussions, they pretty much all go along the same lines: The yaysayers come op with arguments and calculations why a certain weight will be OK.

The naysayer's sole argument is 'don't do this, you significantly increase the risk, stick with Van's numbers', without any reasoning behind this statement.
This is IMHO not very helpful. :(

In my case, we are talking about an increase of the gross weight from 1,800 to 1,850 (+2.8%) or 1,900 lbs (+5.6). Most of the time we would probably stay under 1,800 lbs., the increased gross weight would only be needed for longer trips.
I showed above that the increase of the stall speed is minimal, based on the aerobatic numbers it is also clear that the plane is strong enough to easily carry the additional weight, if it is operated within the limits of the standard category and if the CG also stays within them.

After another day of thinking and research, I still fail to see any other noteworthy risks, caused by such a relatively small increase of the gross weight, other than a possibly increased stress on the landing gear. The suggestion to define a max. landing weight of 1,800 lbs. would however also take care of this concern and document it for future buyers.

Please excuse my persistence, but I want to understand the pros and cons, as we really want a RV-7A, but also don't want to do anything stupid. :)

Let me therefore ask the question again: Which specific risks do you see and why?

I will also discuss this topic with our EAA chapter's technical adviser, I believe we also have at least one aeronautical engineer in our group.
 
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Rv7a

Why beat a dead horse , the 7 is not the plane for you and your mission , give it up ! Can't buy a corvette when you need a Suburban . Go look for a Rv10 or a 182 .
 
Oliver, Is acro flying "something you've always wanted to do" or is it something you've done lots of and like doing? If you're new to acro, might want to spend a few hours in a Citabria with a qualified acro instructor and fly the wings off it - only a figure of speech. You might also want to suugest to your wife that she too get some dual acro. This may help you and your wife assess if you need your next plane to be acro capable.

I like to travel and I like acro so my-7 is right for me. Still, I had my wife take a few hours of dual acro in a Citabria before deciding to buy the -7.
If she hadn't been comfortable with doing acro, or flying a tailwheel, then we would have bought a Mooney for travel and I would have satisfied my acro needs in a rented Citabria.

Robert
 
wirejock said:
My 7a is not finished but I'm trying to keep her light. I carry around enough already.:eek:
Sweetie and I used to travel a lot on our Goldwing. Pretty limited on baggage so we learned.
A few times we shipped stuff to the destination and shipped stuff back.
So basically we will learn to live within the limits of our airplane.
Just a suggestion.
Click to expand...

I agree with this. Every airport of intended landing will have an address and a phone number. Ship the gear and carry a gym bag or two if you plan an overnight. Much easier than weighing/loading etc.
 
Phase 1

Mel said:
Gonna have to jump in here. You must test the aircraft "throughout the aircraft's normal range of speeds and throughout all maneuvers to be executed."

 Vso, Vx, Vy, and the weight and CG location at which they were obtained are the only numbers required to be listed. That does NOT mean that these are the only numbers that require testing.
Click to expand...

The new ops specs only address aerobatic maneuvers. My airplane is non aerobatic. So the only maneuvers I tested were power on/power off stalls. flaps up and down.
I agree with your normal range of speed statement, I tested the airplane to slightly over Vne, which most people on this forum appear to be adamantly opposed to.
 
Weight

Just a brief cursory search turns up information the ferry pilots routinely get approval for as much as 30% over gross for long distance ferry flights.
The original gross weight of the Commanche 250 was 2700#, Max Conrad flew the airplane at nearly twice that weight, and yes, Piper did some calculations that showed the airplane would not break at that weight.
 
jrs14855 said:
The new ops specs only address aerobatic maneuvers. My airplane is non aerobatic. So the only maneuvers I tested were power on/power off stalls. flaps up and down.
I agree with your normal range of speed statement, I tested the airplane to slightly over Vne, which most people on this forum appear to be adamantly opposed to.
Click to expand...

Not sure where you are getting your information, but paragraph (38) contained in the "NEW" op specs in FAA Order 8130-2H are issued in all experimental amateur-built operating limitations, aerobatic or not.
This paragraph includes the statement; "I certify that the prescribed flight test hours have been completed and the aircraft is controllable throughout its normal range of speeds and throughout all maneuvers to be executed, has no hazardous operating characteristics or design features, and is safe for operations."
How can you possibly make that statement without completely testing the entire envelope?

Paragraph (39) addresses flight testing for aerobatic aircraft and is NOT included in the op lims for non-aerobatic aircraft.
 
Testing

Mel said:
Not sure where you are getting your information, but paragraph (38) contained in the "NEW" op specs in FAA Order 8130-2H are issued in all experimental amateur-built operating limitations, aerobatic or not.
This paragraph includes the statement; "I certify that the prescribed flight test hours have been completed and the aircraft is controllable throughout its normal range of speeds and throughout all maneuvers to be executed, has no hazardous operating characteristics or design features, and is safe for operations."
How can you possibly make that statement without completely testing the entire envelope?

Paragraph (39) addresses flight testing for aerobatic aircraft and is NOT included in the op lims for non-aerobatic aircraft.
Click to expand...

I tested from stall to over Vne. Based on 60 years plus flight experience including 50 plus in EAB aircraft, it is my belief that in the case of a non aerobatic aircraft that constitutes the normal range of speeds and then some. The ops specs do not ask for a listing of specific maneuvers for non aerobatic aircraft, other than determining Vso, Vx and Vy.
 
jrs14855 said:
The new ops specs only address aerobatic maneuvers. My airplane is non aerobatic. So the only maneuvers I tested were power on/power off stalls. flaps up and down.
I agree with your normal range of speed statement, I tested the airplane to slightly over Vne, which most people on this forum appear to be adamantly opposed to.
Click to expand...

jrs14855 said:
I tested from stall to over Vne. Based on 60 years plus flight experience including 50 plus in EAB aircraft, it is my belief that in the case of a non aerobatic aircraft that constitutes the normal range of speeds and then some. The ops specs do not ask for a listing of specific maneuvers for non aerobatic aircraft, other than determining Vso, Vx and Vy.
Click to expand...

So your opinion is, If you are not required to list it, you are not required to test it?

I'm afraid the FAA's interpretation disagrees. I understand that I'm a bit of a newcomer having been flying for only 48 years, but I have certificated over 700 experimental and light-sport aircraft and I deal with the FAA on a daily basis.

You may do what you like, but please don't tell others that they don't have to fully test their aircraft.
 
wirejock said:
Something else to consider in the decision.
Aerobatic gross is 1,600 lbs.
You may want to do the math specific to your situation.
Click to expand...

Yes, but fuel carried in the wings isn't included in that GW number.

(I just HAD to toss some more fuel on the fire. Could someone pass the popcorn?)

One other thing, the -7 and -9 do share the same fuselage, with minor differences for the spar.
 
Testing

Mel said:
So your opinion is, If you are not required to list it, you are not required to test it?

I'm afraid the FAA's interpretation disagrees. I understand that I'm a bit of a newcomer having been flying for only 48 years, but I have certificated over 700 experimental and light-sport aircraft and I deal with the FAA on a daily basis.

You may do what you like, but please don't tell others that they don't have to fully test their aircraft.
Click to expand...

Which of the thousand plus FAA's are you talking about. Do you mean the FSDO Inspector who says that if I change from a Sterba 70 diameter 75 pitch to a Sterba 70 diameter 74 pitch that I have to put the airplane back in Phase I for five hours.
Or do you mean Inspector #2 who says that a change from any fixed pitch prop to any other fixed pitch is a minor change and requires only a log book entry.
I performed all the REQUIRED testing on my airplane. You have no personal knowledge of whether I did or did not do this.
 
jrs14855 said:
Which of the thousand plus FAA's are you talking about. Do you mean the FSDO Inspector who says that if I change from a Sterba 70 diameter 75 pitch to a Sterba 70 diameter 74 pitch that I have to put the airplane back in Phase I for five hours.
Or do you mean Inspector #2 who says that a change from any fixed pitch prop to any other fixed pitch is a minor change and requires only a log book entry.
I performed all the REQUIRED testing on my airplane. You have no personal knowledge of whether I did or did not do this.
Click to expand...

No, I'm talking about the DAR instructors in Oklahoma City and the people in Washington DC that interpret the rules.

I'm not concerned with what testing you did on your aircraft. I AM concerned with you telling others on this forum that complete testing is not required.
 
I debated if I should post at all on this thread and I got most of the responses I expected. I provided some information to the original poster who wanted to understand RV-7A W&B. In my experience it is practically impossible to push a typical 7A with Hartzell propeller out the aft limit, even with zero fuel.

As pilots we must always be aware of the current CG location. The 7A becomes very sensitive in pitch low and slow near the runway even within Van’s specified aft limit. A number of people have been caught out.

While I understand some people feel very passionately that Van’s MTOW cannot to be altered. I have taken a practical approach to flight testing. In the western world none of us are getting smaller. I have seen lots of RV’s with two big guys getting in or out. I simply applied some science to it and tested it in Phase I. I rarely fly in that configuration, but I know what to expect if I do. To me that seems like the responsible thing to do.

Remember, our aircraft fly because they do, not because a mountain of paperwork says they will.
 
N941WR said:
Yes, but fuel carried in the wings isn't included in that GW number.

(I just HAD to toss some more fuel on the fire. Could someone pass the popcorn?)
Click to expand...
You didn't include a link to the recent discussion on this topic, and it's not clear whether you're saying this tongue-in-cheek or not. So for the benefit of people not current on the discussion, who may take your comment as gospel, i'll just add that the latest word from the factory is that fuel carried in the wings *is* included in the aerobatic GW number.

See posts #33 and #34 in this thread: http://www.vansairforce.com/community/showthread.php?t=127861&page=4
 
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Testing

Mel said:
No, I'm talking about the DAR instructors in Oklahoma City and the people in Washington DC that interpret the rules.

I'm not concerned with what testing you did on your aircraft. I AM concerned with you telling others on this forum that complete testing is not required.
Click to expand...

Obviously you are stating that I did not test my airplane in accordance with paragraph 38. That is completely untrue.
How many builder/test pilots do you believe tested their aircraft to Vne or above??
Lets use as an example a hypothetical RV7A with Hartzell prop. Most agree that this configuration would be at least slightly nose heavy. I don't know what the baggage limit is for this aircraft, lets use an arbitrary number of 100#. A weight and balance shows that we need 130# in the baggage compartment to reach the aft limit. Are you suggesting that the builder/test pilot exceed the baggage limits in order to test the aircraft at the aft cg limit?? The aft cg limit is something that Vans established long ago and does not need to be tested on each individual airplane. In this case, taken to the extreme, testing could be far more dangerous than not testing. I am not talking about a few pounds. If it took a 30%plus overload of the baggage compartment to reach the aft cg limit, that is potentially dangerous territory.

The OPINION of an instructor at the DAR training is just that, one or more person's opinion(s). That is not regulatory. The Advisory Circular for EAB flight testing is likewise not regulatory.
You have repeatedly accused me of not properly testing my aircraft. You have done this without ANY factual information about how I tested my aircraft. I am not looking for an apology, nor do I want one. I simply want these false accusations to stop.
 
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