National Aeronca Association Bulletin Board

Does anyone know what the typical useful load is for a 7AC?

Wikipedia has the following info:
Empty weight: 740 lb (325 kg)
Max takeoff weight: 1,220 lb (533 kg)

Does this seem accurate to you?

That looks like it leaves me with 480 lbs for fuel and people?

How many gallons of fuel does the tank hold? 13?

Does oil have to be added into this equation as well?

Thanks for helping this newbie out.

-JC

Thanks for the reply, Mike.

So is oil figured at 6lbs per gallon like gas?

If so then 13+1=14 14x6=84
480-84=396 lbs for people and luggage.

I am planning on buying a 7AC.
However, I realize if I take my son with me for a $100 burgers I better make sure they not have cheese on them.



On the brighter side, the hundred dollar hamburger might only cost me $30.

I think I use to remember oil at 7.5 lbs per gal...but 6 is close enough for govt work. As Mike mentioned, the big...big thing in these low powered aircraft to remember is the very reduced climb rate when 2 persons vs 1 on board, or a hot summer day (high density altitude) vs a cool day. 65 horses aren't a lot. That's the big difference between the 65 and the 85 hp machine, so much better climb performance....not that either is ever great when heavy. Of course other popular machines that have gotten people in trouble when loaded and hot vs light and cool are C172s, Cherokee 140s, even C150s. The type prop you have also makes a pretty good performance difference, climb vs cruise prop.

I have just bought a chief with the 75 hp can you tell me what the best all around prop would be for them. I think the one that is on mine is a 70x42 but would have to look again to be sure.

Flyboy (a real name would be nice)

Need a lot more info here. What are you doing, want to do and how is the prop on the plane working now.

Want a climb prop, cruise prop or ?

Welcome onboard!

Joe a

Sorry, My name is John I just want a good all around prop. I fly from a field that is 3000 on east west strip and 1700 north south, both grass. right now it gets off the ground real quick, at about a little over 30 mph but then I have to keep the nose down and build some speed of course.

I dont know how accurate these old airspeed indicators are but seems like it cruises about 75-80 at 3200 rpm. I usually climb out at about 60-65 cause this type of plane is new to me and come in about the same speed. I could probably slow it up a bit but I want to get used to it first. I am going to take my brother in law up tomorrow and then that will give me an idea on what it will do with two people.

Guess I just have to play with it and figure it out as I am used to faster flying planes.This is a great forum with lots of info and am glad I found it. soon as I figure out how to put a pic on here I will do so. John

Think I figured it out with the picture thing.

I am curious if your stated "3200 rpm" is a typo? Did you mean, 2200 rpm?

Mike

John,

Welcome on board!

Very nice looking Chief! Hope you enjoy it.

Your speeds are pretty good as most Chiefs stall around 45 or so, and when I was flying one 60 (65 if windy or gusty) on final was fine slowing to 55 then 50 just before touching down worked well. As you said, the old airspeed indicators may not be totally accurate but then many of us so not use the airspeed on final as much as how the plane feels.

If you are not real current you might get an instructor in the other seat and go out and practice stalls, slow flight and so on. Every plane stalls differently and at different speeds, so you want to find out how it feels at 3000 feet and not 30.

Then you might get a handheld GPS and see what your speeds really are then compare them with the airspeed indicator.

A couple more tips. What tire pressure are you running in your tires? On grass its not as important but we usually recommend 12-14 or so. Too much can make the plane skiddish on landing, especially on hard surface runways. What type of wheels/brakes do you have? If Goodyear then keep an eye on the clips that hold the disks in the wheels. They can pop out and allow the brake disk to get cocked and then life gets difficult on landing. If you have the Clevelands they are good, just keep an eye out for cracking of the wheels. Both are fine and last long but these planes are now 70 years old and deserve some extra attention.

Where are you located? The fly-in held at the original Aeronca factory where your Chief was built is being held in three weeks. Its back at Middletown Ohio and hope you can attend!

Hope this helps!

Joe A

sorry I meant 2300 rpm, I will check the tire pressures and see what they are at. It just had all new brakes put on it about 3 months ago. John

Hi John. Wow...nice looking Chief. I have an A65 Chief. Your A75 is probably a converted A65. The only real difference that made the hp increase is the A75 using a shorter prop that allows it to turn up higher rpms. I looked in the Lasher book about Aeroncas for props. He only has them listed for A65s and C85s. However, a 42 inch pitch for either is pretty flat.

I'm guessing that yours is a climb prop. Is your prop metal or wood? Wood props are generally shorter for the same application. We don't have Aeroncas to go fast, so in a choice between a climb or cruise prop, I'd take the cllimb. I'd much rather have the extra performance for climbing on a hot day or loaded.

My A65 cruises a 87 mph at 2150/2200 with the A65 and a "standard" prop. If you're between 75/80 mph at 2300, again I think you must have a climb prop. For numbers, both Chiefs and Champs, 60 going up and 60 coming down is a good basic number. Of course you can experiment and have higher numbers for cruise climb and a faster pattern descent.

As Joe said. Don't go over 15 lbs with your tire pressure. It's amazing how a bit too much inflation can add a bunch of bouncing. Chief wheel land nicely but I only do them in mostly calm winds. I three point otherwise (that can lead to lenghty discussions and opinions). Maybe someone with and A75 will be able to jump in her with specific prop info. Roger

Hi Roger thanks it is a nice plane. some guy north of me had it and bought a 140 and sold this to me for 19000. I talked to him yesterday and he said he wishes he would have kept it, would I like to sell it back. Lol. The plane had the engine done right to upgrade to a75 it has ifferent pistons and rods and more holes for oil and some other stuff I dont really understand yet. It has a metal prop. I think I will learn a lot about aeroncas on this site and everything I can find out is great. Thanks again, John

John,

A "75 hp" Continental is simply a "65 hp" Continental that is turned a higher RPM to get more power. The power is usually used only on takeoff or climb. The parts changed are the pistons and rods (heavier duty to take the heat) and some other small stuff. I thought that the change called for a venturi change (to allow more airflow) but have had several people tell me that its not needed.

I had a 75 hp engine on my old Chief years ago and loved it. It sipped fuel like a 65 engine when running slow yet gave me the power needed for good takeoff.

Joe A

Hey, Thanks alot guys for the recomended tire pressure. The guy I bought this from had the tires at 22 psi so I dropped them down to 13. Maybe now I won't get that little bounce every once in a while on landing!