Operating cost comparison..a question

[hindsight2020]

Alright folks,

After creating my very own excel spreadsheet (pretty nifty little applet I ended up with), I've decided to get some external POVs on my current dilema.

I am faced with the possibility of having to travel once a month for work (military duty, not all reimbursable..that's for another thread) and started doing some math. Here's the scenario:

306NM one-way, flying direct. Commercial flying is out due to cost and lack of non-stops (neither origin nor destination is a commercial hub= $$$, and the non-reimbursable thing). Driving a 20mpg vehicle takes 8 hours driving one way and 'X' gas cost round trip. Currently own a C-150 (paid off). High time engine. May or may not cut the mustard of doing this once a month. Gyros are not ready for IFR. DG has such bad friction I can't make a turn to a heading in VMC without it instantly lagging 30-40 degrees per 90 deg turn. In the pattern I can "lap" the DG after three touch and goes. I digress. Looking to justify the purchase of a different aircraft in lieu of sinking money into engine and gyros, and decided to incorporate this potential transportation need in order to compare the relative operating cost wrt to my future commutes and desire for aircraft ownership for recreational purposes outright.

Took three samples. C150 @ 85KTGS/6GPH, C172M @ 100KTGS/9GPH, RV-6A @ 140KTGS/9GPH. For the scenario fuel wise, the equivalent of one tankful in mogas due to availability at home field before starting the trip, the rest in 100LL.The results of my applet were rather puzzling...

Turns out with the C150 I shave 8 hours total off the trip versus driving. Stop in the middle required due to short legs so the ETE doesn't account for that stop. At any rate, 4 hours shaved one-way alone puts a smile on my face. 8 hours one way x2 every month driving sounds like a commute that would get old real quick. I don't want to hate the job because of the commute.

So turns out I'd spend $27 extra dollars flying the C-150 in lieu of driving for the benefit of shaving 8 hours of traveling round-trip from the commute. That sounds awesome! Then I got to the C-172 and the results were not as fantastic. I shaved only ONE extra hour round trip over and above the C-150 time, but my additional-cost-over-driving TRIPLED from the C-150 figure, for just ONE additional hour round trip saved over the C-150. WTH?!?! Yeah, figures burning 9GPH and going 100GS didn't help. But, am I giving the 172 a fair shake with that performance fig? Making it a 110GS/8.5GPH helped a little, making the increase in cost-beyond-driving a 76% above the -150 cost. That's still pretty lame. And I still don't know what figure one can rely on for a C-172, and I've flown the things ad nauseam. People's cruise figures are all over kingdom come. 100, 130(yeah right) and everything in between. So I don't know. At any rate..

Then I get to the RV and of course the math goes out the window. That thing is just ridiculous. First of all, the trip can be accomplished non-stop (so can the 172 with a sturdy bladder..or empty bottles )so by eliminating one less partial 100LL fuel-up, I can do one trip on mogas and one on 100LL. Combined that with a rather conservative 140KTGS and I get...wait for it.... a cost of ONE DOLLAR ABOVE driving for the opportunity cost of shaving ELEVEN and a HALF HOURS ROUND TRIP from driving. I about fell off my chair.

So it became clear what I want (the RV...). Now of course, comes the capital outlay of these aircraft. Clearly the 172 and RV would have to be financed, so there goes the savings, case closed. By that measure, the 150 wins by miles...until the engine gives out next week of course..... But, I'm not inclined to make the 150 a long term asset due to outright mission profile desires. Also, said mission does not require a third seat, so there may be other 2 seaters (experimentals preferred) out there I've missed that could take the place of the C172 in my analysis and provide a cheaper alternative to the RV-6A (the ideal), while releasing my soul from the catacombs of cruising along @ traffic pattern speeds and dead gyros (the 150) just because I happen to swim in the 2-seat market.

I open the floor for suggestions or ideas from the as usual surprisingly insightful and colorful POA crowd...

 

[Anthony]

Create all the spreadsheets you want, but throw them away when you actually own and operate an airplane. These are unpredictable devices, and zing you whenever they can with unexpected costs, sometimes very LARGE costs.

Are you buying a plane for this one trip or are you going to fly it after it? The RV provides a lot of fun factor other than speed and range.

 

[SCCutler]

Also, consider an older Bonanza; you'd be amazed at just how efficient they can be (I fly lean-of-peak, 162 knots TAS, 12.1 GPH), and the deals out there, just now, are simply amazing.

 

[taters]

call aircraft quality instruments in Wichita, they will exchange your gyros up front for $365 a piece.

 

[Capt. Geoffrey Thorpe]

Compare the cost / performance of a T-18 to the RV-6.

 

[poadeleted20]

Before you go digging into an RV-6 or other Experimental as a traveling plane, take a good look at all the issues of flying an amateur-built plane, and the size of the interior of mini-fighters like the RV's (except the -10). Also, you don't say what you're using for costs, and if you found the cost of making this trip triples with a 172 over a 150, I suspect your costs are a bit off. If you'd like to see the paper I put together on the ownership and operating costs of a typical simple 4-seater, email me.

And that's email, only, thank you -- no PM's, posts, phone calls, thought waves, or smoke signals.

 

[Trapper John]

Compare the cost / performance of a T-18 to the RV-6.

The T-18 is a really neat plane, but it has a pretty snug cockpit. There's a wider version, I think it's the S-18? Another one to look at would be the Mustang II. From what I've seen the RVs tend to have the best equipped panels, though, so that may account for part of the price difference.

 

[RMCN172RG]

I don't see any consideration on dispatchability. Obviously there will be n number of times that you will or should not fly and the plane will sit on the ground while you make the 8 hour round trip via car.

How much are you willing to spend in additional fixed costs to let shiny new fast plane sit on the ground?

 

[jesse]

Your numbers are all screwy. A C172M will do better than 100 knots at 9GPH. More like 110 knots at 8gph. 306NM non-stop is a piece of cake in a 172.

 

[wabower]

OTOH, who guarantees the 8-hour trip time in the car? I can't seem to drive anywhere without numerous lane closings and orange cone aggravation. One of our long-tooth Lear operators used to say that flying any airplane (150, etc.) was the quantum leap over driving, and that everything else was incremental. I'd put some rebuilt gyro's in the 150 and fly the trip for six months. Then he will know how it works rather than guessing at it. I sure as hell wouldn't spend a lot of money to fly non-reimbursable trips.

OBTW, to provide meaningful information, airplane ownership/usage spreadsheets must include a full-cycle analysis. Add purchase price and all other costs, deduct a range of estimated net resale proceeds out, divide results by hours flown.

I don't see any consideration on dispatchability. Obviously there will be n number of times that you will or should not fly and the plane will sit on the ground while you make the 8 hour round trip via car.

How much are you willing to spend in additional fixed costs to let shiny new fast plane sit on the ground?

 

[EdFred]

OBTW, to provide meaningful information, airplane ownership/usage spreadsheets must include a full-cycle analysis. Add purchase price and all other costs, deduct a range of estimated net resale proceeds out, divide results by hours flown.

And do the same thing with the cars. How come no one ever does that?

 

[murphey]

1) Rebuilt/new DG is considerably cheaper (2-3 orders of magnitude!) than buying a replacement airplane.
2) What causes you to suspect the engine? How high is "high-time"? As a rule, the less an engine is run the more questionable it becomes. Engines really like to run.
3) Do you need the additional space/seats of the 4-place (C172)?

I agree with some of the others on here - fix the DG now. It's the lowest-cost solution in the short term. Altho the trip is not reimbursable, it's probably a legit tax deduction. If it isn't complain to your congresscritter!

Fix the DG. Spend a few months doing the trip (or have you already?) and see how it goes. Airplane prices are probably not going to change much in the next few months, other than going down - to your benefit.

Hm...military guard/reserve duty 300 miles from LA....now where could that be? (*eeeevil laugh*)

 

[CJones]

If you're sure you won't ever need the 3rd seat, RV would be a good fit. 140kts is a pretty conservative number. We get 160KTAS out of the -7A burning 10.2GPH ROP - when we get up high, we go LOP and end up down around 7-8gph and 150-ish KTAS.

150kts for 306nm puts you right at 2 hrs one-way - plus you could do barrel rolls along the way if you get bored. It's a stable enough IFR platform (did 90% of my IR training and 100% of IR checkride in -7A). You can get some pretty sweet radios in the 'experimental' market for quite a bit less expensive than the 'certified' market.

The nice thing about the RV market is that you can be pretty sure to find one in just about every price range with the dominating factor in RV prices being tied to the panel. A thorough pre-buy by a type-knowledgeable A&P is key for any experimental purchase.

Nice thing about the RV that the 172 won't get you - if you're going on a long trip, you can put on the O2 and head on up to 14-15k and catch some snappy tailwinds (I've had the -7A up to 16,500'). When I was coming back from Las Vegas a few years ago, I could have gone non-stop from Santa Fe, NM to central Iowa thanks to being able to get up high to get a 40-50kt tailwind -- good luck getting a 172 to crawl up that high.

I'll admit - I am biased, but so what.

 

[wabower]

Just did for the Lex. More than you'd think. Depreciation alone was $4k/yr. Fuel was ~1.8k/yr. All-in costs were 36k for 65k miles over 5 years. Do the math.

And do the same thing with the cars. How come no one ever does that?

 

[jesse]

good luck getting a 172 to crawl up that high.

I've taken a 172P up to 14,000 ft and it still had plenty of climb left in it. That said - I was about 150 lbs, solo, and half tanks.

 

[AuntPeggy]

Your numbers are all screwy. A C172M will do better than 100 knots at 9GPH. More like 110 knots at 8gph. 306NM non-stop is a piece of cake in a 172.

I get 105 kt at 7.5 gph flying at 75%. We have the 180 hp mod.

 

[jesse]

Just did for the Lex. More than you'd think. Depreciation alone was $4k/yr. Fuel was ~1.8k/yr. All-in costs were 36k for 65k miles over 5 years. Do the math.

Should have bought a Sunfire. 105,000 miles over 5 years. Total $18850 including the purchase cost, maintenance, fuel, and insurance. Didn't take into account registration but that was under $100 per year.

We'll see what the numbers on my $700 Concorde that I bought with 165,000 miles works out to....will report back in 4 years.

 

[Trapper John]

For a O-320 powered 172, I flight plan for 105 kt, 9 gph 1st hour, 8 gph thereafter. Might true 110, might not...

 

[Ted]

I think that you're underestimating the 172 in terms of its performance figures and overestimating the cost. No way should it be triple the cost. If you look at wet rental rates per hour for both aircraft, that should give you an idea of how much more a 172 costs to operate.

As far as aircraft, Spike makes a good point with an early Bonanza. One of my friends did the comparison between an A33 Bonanza and her Cherokee 180, and found that the Bonanza ended up getting similar mpg while going a lot faster. Mooneys are also pretty efficient, and I was happy with the M20F model I flew. Flying one of the C or E models would be even more efficient/faster, and if you're currently in a 150 then the space shouldn't bother you. A Comanche is also a great value, just ask Ed.

As far as costs go, it would be good to figure out what your car actually costs you per mile, factoring in depreciation, etc. Flying will probably cost you more, but the question is how much can you get out of your employer (military, whatever) for the travel, and what is your time worth to you. I'm at the point where I have to be convinced pretty heavily to drive unless I'm getting paid for it. My company will pay me to drive by the mile, so I do. For virtually all personal travel over 3 hours driving time, I'm flying. Costs more, but I'm happier.

Trying to use a 150 for dependable transportation I think isn't a great idea. It's not an all-weather plane, it's not fast, and when dealing with things like thunderstorms you're a significant disadvantage. I recall you're in a warmer climate so de-ice is probably less of a concern for you.

I'd take a serious look at some of the retracts out there and see what you can find.

 

[wabower]

I'd just as soon shoot myself.

Should have bought a Sunfire. 105,000 miles over 5 years. Total $18850 including the purchase cost, maintenance, fuel, and insurance. Didn't take into account registration but that was under $100 per year.

We'll see what the numbers on my $700 Concorde that I bought with 165,000 miles works out to....will report back in 4 years.

 

[EvilEagle]

I bought the Glasair to commute to work (96 miles, but a 3 hour drive due to traffic). The USAF doesn't pay me to do it either, but on TDY's it does.

If you are hell-bent on a new airplane, def look into experimentals. Our Glasair is 150 kts true all day long and ends up being between 7-7.5 gph if you are doing longer legs. I plan on 8gph doing the short hop to work.

 

[Cap'n Jack]

And do the same thing with the cars. How come no one ever does that?

Possibly because most people have a car and it's a sunk cost. Insurance, some maintainance, and most depreciation happen whether the car is used or not. If the trip forces the mileage over that contracted in the lease, the costs will go up.

It still wouldn't hurt the run the incremental numbers for this trip (gas, mileage if on a lease, increased maintainance, etc)

 

[hindsight2020]

Awesome responses! Thanks a ton.

I agree, the gyros would be a relatively easy and "cheap" fix. Will probably do that before I attempt the first batch of commutes. The issue of govt reimbursement is still out there. It may be, it may not. I do concede I was doing this math exercise taking into consideration my desire for flying for recreational purposes. I.e. doing a 306NM commute once a month would not be the PRIMARY reason for the acquisition of the aircraft. It wasn't the case for the 150 and it wouldn't be the case for an RV-6A.

As far as dispatchability, yes I took into consideration that I would not be able to make all twelve trips a year by flight. I consider that a sunk cost. What would keep me from launching a -150 will keep me from launching a 172 or RV-6A, generally speaking. My hangaring costs would be the same (no hangar right now for a peeling paint 150, so I'm saving a bundle there). Keeping it in the family of fixed gear trike fixed prop keeps the insurance around the same ballpark (no more than $1300/yr). So there's no appreciable fixed costs that make or break the equation just because I would have to drive some months.

The RV is pretty much the way to go, but it seems to be the most expensive route, if I account for the capital outlay.

The Bo is a great aircraft but it's too much airplane for what I'm trying to accomplish, insurance, RG and CS mx-wise et al.

Regarding the 172, I'm sorry folks but looking at several replies on this very thread confirms my initial point,and that is that the numbers are all over the place. 110TAS at 8gph? Nah, I don't think so. the book may say so...my C-150 book says I can do 106 TAS at 5.8gph and I can assure you that isn't half as true. 105TAS @ 9gph sounds like a good compromise for the 172M and running my little applet still yields a marginal increase in time saved..an hour and a half round-trip over the -150.

As far as the "tripling cost" comment, yall may have misunderstood what I meant. I took the added cost above the car "control group" and normalized it across the amount of hours I would be saving in travel time for each case study. So for the 172, because I only gained an hour of travel time saved versus the C-150, but I did it in the process of burning 3gallons per hour more for the trip, the "cost per hour saved traveling" effectively tripled. The total cost only increased 20% from the C-150 commute cost. But because my capital outlay would be the same as the RV-6A, the 172 becomes a poor "compromise" for the added cost. Now, I did carry an airplane across the sky with more than two seats, so I'm willing to account for that, but since my mission doesn't require hauling all that empty space, the cost is as useful as the runway behind me. So no, the total cost does not triple, but the per hour saved cost does. Meaning it's a lot of extra expense per mile for only an hour gained round trip. I'd be doing it on a wider cabin though, that may or may not be worth it to me. Not sure I want to get into a run-down 172 just to make the numbers work when I'm still gunning for an RV-6A. I guess I'm trying to find other 2-seat alternatives to the RV (trike, don't want to deal with the hassle or insurance premium of a TD...and the endorsement cost). I just haven't found that mythical 2-seater between 150 and RV-6 cruise speeds. If anybody could throw some models my way I'd love to run a comparison! For now it looks as though the 150 is the best overall value to accompish this trip when accounting for capital outlay....

Cabin width is a concern of mine. I fit these two seaters fine, but 150s are cramped man. Never sat on an side by side RV but my understanding is that shoulder-room-wise they are as "comfortable" as a 172. And 172s aren't wide by any means. But it's leaps and bounds better than a 150. I know leg room and head room is better on a 172 than both 150 and RVs, and I do prefer two doors or canopy in lieu of single door.

*goes back to crunch numbers*

 

[tonycondon]

i guess our club 172's are just fine examples of the type because it seems that I routinely get 110-115 knot true airspeeds at 6-8000 ft, WOT, leaned to the edge of rough. in other words, book numbers. I think it helps that I usually have as much weight as possible as far back in the baggage area as possible.

 

[jesse]

i guess our club 172's are just fine examples of the type because it seems that I routinely get 110-115 knot true airspeeds at 6-8000 ft, WOT, leaned to the edge of rough. in other words, book numbers. I think it helps that I usually have as much weight as possible as far back in the baggage area as possible.

I've never had a problem getting book numbers in a 172 either. I think a lot of people just forget about true airspeed.

 

[tonycondon]

i think it also has to do with a lot of people running around at 2400 RPMs or even 2500. 75% power is usually around 2600 give or take unless you are way down low.

 

[schmookeeg]

What about a sportier certified 100/160hp option into the mix? Grumman AA1/AA5 series comes to mind. There's a guy here who flies an M10 Mooney Mite and made me jealous with his professed numbers. I assume M10s are VFR-only craft, though. Also, luckily, I will never be in danger of fitting comfortably in an M10, so the point is an academic one for me.

I assume the runways at each end are long enough and paved enough to support these sorts of planes... (unless I missed something in my reading)

The RV may gain something in the form of cheaper maintenance. Are RV6's in IFR kitted form inexpensive?

Cool problem to have, btw.

 

[wabower]

Use block times rather than cruise speed for trips. You'll find that moving up a step (from a 150 to a 172 etc) won't yield enough time difference to notice on most trips. Moving up two steps (from a 150 to a 182 or maybe a 172RG) might yield enough time savings to measure, but the time spent at stop lights and in the men's room will have more impact on door-to-door travel times than will the selection of airplane used.

Awesome responses! Thanks a ton.

I agree, the gyros would be a relatively easy and "cheap" fix. Will probably do that before I attempt the first batch of commutes. The issue of govt reimbursement is still out there. It may be, it may not. I do concede I was doing this math exercise taking into consideration my desire for flying for recreational purposes. I.e. doing a 306NM commute once a month would not be the PRIMARY reason for the acquisition of the aircraft. It wasn't the case for the 150 and it wouldn't be the case for an RV-6A.

As far as dispatchability, yes I took into consideration that I would not be able to make all twelve trips a year by flight. I consider that a sunk cost. What would keep me from launching a -150 will keep me from launching a 172 or RV-6A, generally speaking. My hangaring costs would be the same (no hangar right now for a peeling paint 150, so I'm saving a bundle there). Keeping it in the family of fixed gear trike fixed prop keeps the insurance around the same ballpark (no more than $1300/yr). So there's no appreciable fixed costs that make or break the equation just because I would have to drive some months.

The RV is pretty much the way to go, but it seems to be the most expensive route, if I account for the capital outlay.

The Bo is a great aircraft but it's too much airplane for what I'm trying to accomplish, insurance, RG and CS mx-wise et al.

Regarding the 172, I'm sorry folks but looking at several replies on this very thread confirms my initial point,and that is that the numbers are all over the place. 110TAS at 8gph? Nah, I don't think so. the book may say so...my C-150 book says I can do 106 TAS at 5.8gph and I can assure you that isn't half as true. 105TAS @ 9gph sounds like a good compromise for the 172M and running my little applet still yields a marginal increase in time saved..an hour and a half round-trip over the -150.

As far as the "tripling cost" comment, yall may have misunderstood what I meant. I took the added cost above the car "control group" and normalized it across the amount of hours I would be saving in travel time for each case study. So for the 172, because I only gained an hour of travel time saved versus the C-150, but I did it in the process of burning 3gallons per hour more for the trip, the "cost per hour saved traveling" effectively tripled. The total cost only increased 20% from the C-150 commute cost. But because my capital outlay would be the same as the RV-6A, the 172 becomes a poor "compromise" for the added cost. Now, I did carry an airplane across the sky with more than two seats, so I'm willing to account for that, but since my mission doesn't require hauling all that empty space, the cost is as useful as the runway behind me. So no, the total cost does not triple, but the per hour saved cost does. Meaning it's a lot of extra expense per mile for only an hour gained round trip. I'd be doing it on a wider cabin though, that may or may not be worth it to me. Not sure I want to get into a run-down 172 just to make the numbers work when I'm still gunning for an RV-6A. I guess I'm trying to find other 2-seat alternatives to the RV (trike, don't want to deal with the hassle or insurance premium of a TD...and the endorsement cost). I just haven't found that mythical 2-seater between 150 and RV-6 cruise speeds. If anybody could throw some models my way I'd love to run a comparison! For now it looks as though the 150 is the best overall value to accompish this trip when accounting for capital outlay....

Cabin width is a concern of mine. I fit these two seaters fine, but 150s are cramped man. Never sat on an side by side RV but my understanding is that shoulder-room-wise they are as "comfortable" as a 172. And 172s aren't wide by any means. But it's leaps and bounds better than a 150. I know leg room and head room is better on a 172 than both 150 and RVs, and I do prefer two doors or canopy in lieu of single door.

*goes back to crunch numbers*