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RV-7 engine and prop?

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Pitts25

Member
I'll be shopping for a flying RV-7 at years end. I have noticed that some builders have chosen to install O-320's w/fixed pitch props. I am of the understanding that the 7 was designed specifically for a heaver 360 w/ constant speed prop. If this is the case, how are these lighter engines and props being accommodated; longer mounts? extra weight on the nose?

Additionally, will I pay much of a penalty in speed for the nose wheel if I buy an A? I would like my wife to be able to safely land if I croak so I may be in the market for a training wheel on the front.

Thanks for any answers.

Dennis
 
I can't answer the W+B question, but research the nose dragger deal carefully. It can be quite a debate so I don't want to stir the pot here, but I do want to mention that buying a -A will pretty much restrict you to pavement because it's known to fail and flip the airplane if it experiences any significant resistance.

There are certainly a lot of advantages of a -A, but I don't think anyone will argue against the conventional gear being significantly stronger.

schu
 
I flew my 7A off a 1700 ft grass strip for 4 years with never a mishap. Flown properly, an A model will be safe as any plane on grass runways. The 0-360 A1A and the Hartzell BA prop is an excellent combination and will balance very nicely in all realistic configurations.

Roberta
 
Do your own research on the tail wheel vs nose wheel debate, and don't be swayed by the fear mongers. For an inexperienced pilot trying to land in an emergency, I'd take the tricycle gear anyday. As always, my 2 cents, YMMV, don't try this at home, eat your vegetables, etc.
 
akschu said:
I can't answer the W+B question, but research the nose dragger deal carefully. It can be quite a debate so I don't want to stir the pot here, but I do want to mention that buying a -A will pretty much restrict you to pavement because it's known to fail and flip the airplane if it experiences any significant resistance.

There are certainly a lot of advantages of a -A, but I don't think anyone will argue against the conventional gear being significantly stronger.

schu
Click to expand...

schu,

Such a statement serves no useful purpose whatever, it is a gross exaggeration of the NG issue. "A" model airplanes can be and are flown off of grass without incident on a regular basis. Your source of information is faulty and does not reflect the situation accurately.

For best flying qualities, keep an airplane as light as possible with as much HP as possible without going fat. The RV-7A with a light weight IO360 and Catto prop does not have an aft CG problem, nor does it have a forward CG problem - in fact it is just right.

This engine and prop is a very satisfying compromise in this matter. :)
 
MY THREE CENTS?

I have a 9-A and I would say in most situations the nose wheel is probably a safer combination for a person with limited experience. I learned in tail dragers and have Approx. 8K Hrs. is them. To me tail or nose wheel is irrelevant! If you were to croak, and your inexperienced passenger were to attempt an emergency landing the outcome most likely won't be a desirable one. The nose wheel is surely easier to land on a smooth surface and in a extremely hard landing on inhospitable terrain the sheering off of the nose gear well impart a considerable amount of energy and possibly lessen the final impact. There are many factors to consider and countless scenarios that you can't begin to explore, so bottom line is! "No correct answer". I like them all and each Has distinct advantages. The insurance is cheaper an the "A" model, so statistically at least the nose wheel is safer. Glad I was able to clear all this up for everyone!!!!!
Regards all, Allan:confused:
 
Pitts25 said:
I'll be shopping for a flying RV-7 at years end. I have noticed that some builders have chosen to install O-320's w/fixed pitch props. I am of the understanding that the 7 was designed specifically for a heaver 360 w/ constant speed prop. If this is the case, how are these lighter engines and props being accommodated; longer mounts? extra weight on the nose?

Additionally, will I pay much of a penalty in speed for the nose wheel if I buy an A? I would like my wife to be able to safely land if I croak so I may be in the market for a training wheel on the front.

Thanks for any answers.

Dennis
Click to expand...

The 0-360 isn't meaningfully heavier than a similarly equipped 0-320. The angle valve IO-360's are heavier than the other engines.

That said, your choice of prop and starter has a huge impact on the airplane's CG. A firewall forward package of a metal constant speed prop, governor, and heavy starter can be 60+ pounds heavier than a firewall forward package with the same engine with a lightweight prop and starter. A fixed pitch metal prop and light weight starter combination will put you *about* halfway between the extremes.

The bottom line is that you can go with whatever engine makes sense for you, as long as you choose accessories to match your mission. An additional consideration is where you locate your accessories. There are a number of items that can be mounted in alternate locations if you're trying to tweak the CG. For instance, the ideal place for the ELT is way back in the tailcone. It'll probably get less damage in a crash if located there. BUT, from a CG perspective, the aft fuselage may not be a good location for some airplanes. In mine, the ELT is located in the footwell just behind the battery box.

And nosegear vs tailwheel? I wouldn't go into a rough field with an -A model, but otherwise, I think both are fine if the pilot is doing his job properly.
 
Pitts25 said:
I'll be shopping for a flying RV-7 at years end. I have noticed that some builders have chosen to install O-320's w/fixed pitch props. I am of the understanding that the 7 was designed specifically for a heaver 360 w/ constant speed prop. If this is the case, how are these lighter engines and props being accommodated; longer mounts? extra weight on the nose?

Additionally, will I pay much of a penalty in speed for the nose wheel if I buy an A? I would like my wife to be able to safely land if I croak so I may be in the market for a training wheel on the front.

Thanks for any answers.

Dennis
Click to expand...

Croaking in flight is distinct risk factor and the meter goes up with age. That's why commercial flights have at least 2 pilots. (we all will eventually croak somewhere sometime so why not factor it in flying these airplanes with regard to passengers)

My take on it is I don't give rides to people who can not fly unless they come crawling on hands and knees and have no dependents, and that includes my wife who doesn't seem to mind the caveat. She can not fly and does not want to die in an airplane if I do, not at all an unreasonable point of view.
 
will I pay much of a penalty in speed for the nose wheel if I buy an A?
Click to expand...

About 2mph


RV-7A Performance
160 hp 180 hp 200 hp
Top Speed 200 mph 208 mph 215 mph


RV-7 Performance
160 hp 180 hp 200 hp
Top Speed 202 mph 210 mph 217 mph
 
Different engine mount!

Hello,

Vans have a 2" longer engine mount for the 320 to correct the lighter engine.

low fuel does not count much, it is directly on the CG.

I'm building a RV-7a with a IO-320. Here in Switzerland we have a few RV6 and 7 with 320 and it is not at all a slow plane.

I reguraly fly a Slingsby firefly, it has a IO-320 and a constat speed prop.
If I (alone on board) follow a RV6 or 7 (with two on board and sensenich FP), I can not follow, the RV's are earlyer in the air and climb faster, they have to wait for me, even if I run full power. The RV will be faster and climb better than anithing that I was flying before, so I'm fine with this.

The main problem is, vans designed them as a taildragger and later on redo them ino a A version. Even if you do not install anithing adittional in the back, it tend to be tailheavy.

Regards, Dominik
 
The engine mount is 2" longer for the 320 to go on a 7 (actually designed for a 320/CS prop combo). I have that mount, but ended up with a 360 anyway because I found a good deal. The numbers in cruise are so close, it's almost a wash. The 360 will climb better, but cruise is close, and fuel burn is better on the 320, obviously.
 
Thanks for all the great info, all good stuff that I can use when I make my choice.
My wife can fly enough to get a nose dagger back down but has always struggled with a tailwheel, maybe I can just give her a little more dual because I prefer a tailwheel and I'll always take 2 mph. I know she would pay more attention with an instructor other than me.

A friend and I, both Tailwind owners at the time, weighed my HIO-360 and his O-320 both with only a set of Slick mags installed. There was a 9 lb total difference in wt. We were using very accurate scales. I like the suggestion of an IO-360 w/Catto, good compromise and I love Craig's props.

Thanks
Dennis
 
Well I have flown for nearly 200 hours with an O-320, with WW 151 prop, and Sam James Cowl.

I climb faster than an O-360 with a fixed pitch, and slightly slower than an O-360 with a constant speed. But keep in mind that you will likely NEVER climb out at maximum. The deck angle to get these extreme climb numbers is so high that I only used them in flight testing. When I am going somewhere, I climb out initially at about 100 kts, and then convert to a cruise climb of 120 KTS. I consistently see 1500+ feet per minute, tapering off as I climb.

As for Cruise, and Top speed, my plane is faster than many o-360's and slower than some. Top Speed for me is 178.2 Knots (based on spreadsheet), which is just a tick slower than Van's numbers for a 180.

I can vary my cruise numbers (fuel/speed) from 8 ish per hour in the 165 KT range, down to 6 gph at 145 kts, depending on how fast I want to get there, and if I need to stretch it to avoid a short leg fuel stop. I have cruise home at 170+ kts to beat an approaching system.

My cruise flows and speeds are within a few knots of an O-360.

In my opinion the difference is way overated. I would note however that I have flown an O-320 with a fixed prop, and it was a bit doggier on takeoff roll, but still fully capable and more capable than the certifieds.

The O-320 has been easy to cool, and I can climb directly to 8500 feet without any temperature limits. I have limited the baffel entry into my oil-cooler mini-plenum, and the result is that in the summer it runs at 185 all the time, and in the winter is never bellow about 150 degrees.

It is my personal opinion that the O-320 is smoother...shorter stroke.

Oh, and the longer mount, plus longer prop hub give it a more long nosed appearance which I think is awesome!

Here it is in the finished thread:
http://www.vansairforce.com/community/showthread.php?t=1744&page=23


http://img183.imageshack.us/i/dsc00427e.jpg/

And the for sale thread :(

http://www.vansairforce.com/community/showthread.php?t=63345

JC
 
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