Kitfox IV-1200 for Two

[AMK53]

Is Kitfox IV-1200 a good purchase if I plan on flying with myself and my wife about 50% of the time? My wife and I aren't particularly heavy (140 and 170 lbs), but based on what I read online, the useful load on these is about 420 lbs. That means that we would always have to fly with 18 gal or less to stay under gross. I know a lot of people fly them and clearly it's a two seater, so there must be plenty of people flying it with a partner. Do you just ignore the gross weight or sacrifice the range?

The IVs relative availability and the price point makes it attractive, but the useful load is a bit of a turn off. Thanks for the help!

[avidflyer]

Kitfox 4 classic is 1200 lb gross weight. With a 912 rotax, that plane may well weigh in at about 650 lbs, maybe even a bit less. You could also have a way heavier engine then the 912 and load it up with lots of stuff, and then your empty weight could be way higher then the 650 lbs. Point being, it all depends on how heavy the plane is. Also, burning about 4 gph like the 912 should do, you can probably carry more fuel then your bladder can handle even with 18 or 20 gallons on board. JImChuk

[jrthomas]

Let's do the math. Assuming you Kitfox 4 is 912 powered, 700 pounds would lean to the heavy side but it'll keep the math simple. So you and you wife's weight combined is 310 pounds and 25 gallons of gas comes to 150 pounds. That's 460 pounds total so you're still 40 pounds shy of 1200. I don't see a problem.

[AMK53]

The particular airplane that I am looking at has a useful load of 418 lbs but let’s round and say 420. So the weight breakdown is:

1. Me: 170 lb on a good day
2. Wife: 140 lb on a good day
3. 26 gallons of fuel @ 6.16 lb/gallon = 160 lb

Total = 470 lb which puts you 50 pounds over gross. To say under gross you’d have to fly with ~ 18 gallons.

By your math, I’d have to get an airplane that’s about 50-60 lbs less weight.

[Jerrytex]

Wonder what is making this KF 4 so Heavy?

My KF 4 weighs 689 (912 80hp) so that gives me a useful load of 511.

Does this plane have a subaru?

[AMK53]

I'm not sure. It's a 80 hp 912. I'm not familiar with a IV, so I am not sure what to expect on the useful load. I figured what it had was average. I can always gut it a little bit to shed some weight. The inventory is fairly low on Kitfoxes, so what you see is what you get.

[efwd]

Anybody other than the airplane need to lose some weight? ;)

[AMK53]

We just had a newborn so losing weight would probably cost us more money than the plane :p

[jrthomas]

It's hard for me to believe that a model 4 with a 912ul could be that heavy. I'd find an A&P with some certified scales that weigh all three points at once, make sure to level it correctly, drain all the gas and weigh it again. Speedster's are heavier but not that much heavier. If it really is that heavy I'd start pulling unnecessary stuff out. One of my buddy's recently bought a model 4 with a tape deck. You said you were unfamiliar with the model 4. In my opinion it's the jewel of Kitfox line. Maybe not quite as refined as the later models but a great performer with its lighter weight. I believe a model 4 with a 912ul and the right prop is every bit the equal, performance wise, to a 100hp model 5 thru 7, at half the price on the used market. Put it on a diet if it really is that heavy and enjoy it. I still have my doubts.

[109JB]

Why would a speedster be heavier? They have shorter wings, and a few light plywood ribs in the tail surfaces but I would think they could/should be lighter than a long wing. Am I missing something?

[AMK53]

It's hard for me to believe that a model 4 with a 912ul could be that heavy. I'd find an A&P with some certified scales that weigh all three points at once, make sure to level it correctly, drain all the gas and weigh it again. Speedster's are heavier but not that much heavier. If it really is that heavy I'd start pulling unnecessary stuff out. One of my buddy's recently bought a model 4 with a tape deck. You said you were unfamiliar with the model 4. In my opinion it's the jewel of Kitfox line. Maybe not quite as refined as the later models but a great performer with its lighter weight. I believe a model 4 with a 912ul and the right prop is every bit the equal, performance wise, to a 100hp model 5 thru 7, at half the price on the used market. Put it on a diet if it really is that heavy and enjoy it. I still have my doubts.

Thanks for the comments. I'm still waiting to hear back from the seller if the deal can be made official, but your words give me more hope that I won't end up regretting the decision. At this point I am open to any model IV and up but the used inventory is just non existent right now.

[jrthomas]

Why would a speedster be heavier? They have shorter wings, and a few light plywood ribs in the tail surfaces but I would think they could/should be lighter than a long wing. Am I missing something?
Speedsters have a radiator scoop, sometimes wheel pants, and ribs in the tail, both vertical and horizonal. Little things that add up. Grove gear adds weight. My model 4 has all the Speedster stuff but with the long wing. I built it as light as I could with basic panel, no transponder and a light weight Becker radio and it was still heavier than I had hoped. I don't have wheel pants but I do have a Grove gear and 22" Dessers. I first weighed mine with bathroom scales. I weighed it a second time with my A&P buddy's certified scales. The certified scales showed about 50 pounds heavier than the bathroom scales. My flying buddy also weighed his model 4 Speedster with the same certified scales and his plane also weighed a good bit more his data plate says. So I'm a little suspect of some of those super light weight model 4's. Either way I couldn't be more pleased with mine. Or, maybe the bathroom scales were right and those high priced certified scales wrong. Could be!

[109JB]

OK so you are saying that in general Speedsters are heavier, but only because of installed equipment that could be outfitted to any kitfox or omitted from any Speedster. I don't really think it's fair to use a blanket that "Speedsters are heavier" without noting that it is the options that do it. The grove gear is a popular option for long wing and speedster variants, as are just about all of the options you mentioned. Bottom line is that a comparably equipped long wing Kitfox should actually weigh more than a Speedster. If you don't take the installed options into account you are comparing apples to oranges.

Most heavy airplanes aren't heavy because of the airplane but because of the full stack of radios, too much paint, full upholstery, heavy options, etc. If I were looking at buying an airplane that shows heavy on the W&B, I would be looking at it with a critical eye to see what can be changed to make it lighter. A heavy airplane can often be lightened up significantly just by removing unnecessary junk. What can't be easily changed is paint and airframe weight.

[jrthomas]

I didn't realize I was being "unfair." Adding Speedster options add some weight, especially in the tail. I believe the few pounds of added weight are well worth the tradeoff for improved handling. I totally agree that excessive weight is mostly in the cabin. But things being equal, the extra stuff that makes a model 4 into a Speedster has got to weigh something. So the identical Kitfox with Speedster options will naturally weigh a little more, not a ton more but more just the same. All of us have seen planes with panels that look like a 747 panel. If the Kitfox we've been talking about really weighs 782 pounds, there's some excessive stuff in there that could go. I bought my model 4 unbuilt kit along with a vacuum pump and vacuum driven instruments. I removed the pump and never used the instruments. The weight just wasn't worth it. The lighter the better.

[HighWing]

Let's do the math. Assuming you Kitfox 4 is 912 powered, 700 pounds would lean to the heavy side but it'll keep the math simple. So you and you wife's weight combined is 310 pounds and 25 gallons of gas comes to 150 pounds. That's 460 pounds total so you're still 40 pounds shy of 1200. I don't see a problem.

Love the above statement. In fact, the baggage sack is limited to 40 lbs. so perfect.

I have built two Model IV-1200s. The first one weighed 704 lbs. The second 675. Both had the speedster options, but the first also had full upholstery, carpet and covered kick-panels. On the second, I did all I could think of to save weight and it was modestly successful. My target weight was what my buddies IV weighed empty - 604 lbs, a full hundred pounds lighter than my first one. He always flew with his son - everywhere - and as his son grew, he went from probably a 70 lb. kid to a full grown man. Another thing I always thought of was the weight of the camping equipment 1.4 lbs for a +20 degree sleeping bag and my 6 lb. tent. One more thought on build weight. The original IVs came with the light weight uncertified fabric weighing 1.87 oz. per sq. yd. Most builders today, even those building the IVs and earlier are using the medium weight fabric - 2.79 oz. Not a lot of weight, but keep in mind, the heavier fabric will absorb more of the finishing liquids so will be several pounds heavier than the original design. To each his own on the safety factor, but again, there has never been an in-flight structural failure with any model Kitfox. My buddy liked the heavier fabric because his cat that loved crawling over his IV didn't do as much damage with the heavier covering. Recently someone posed something like recognizing that the grams added will turn into pounds - a good thing to keep in mind.

[HighWing]

Another thought on the Speedster options, Elevator trim. consists of an electric servo, the wiring needed and some welding and modification of the elevator to accommodate the trim tab. How much does it weigh?
Who knows for sure, but I felt I needed it on both builds as the thought of trimming with the flaperons seemed in my simple mind a bit challenging - back in the day.