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Altitude & Acro

MikeJ 7A

MikeJ 7A

Active Member
For those of you using your RV to perform some standard, positive G acro, what MSL altitudes are you comfortable at? I hope to do acro with the -7A I'm building here in western SD and terra firma in these parts is around 3000' MSL. Is the loss of performance at these altitudes likely to be an issue?

MikeJ
 
My personal limit is double that of FAAs. 3000' AGL. I don't consider MSL a big factor.
 
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MikeJ 7A said:
I'm building here in western SD and terra firma in these parts is around 3000' MSL. Is the loss of performance at these altitudes likely to be an issue?

MikeJ
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I know this is a genuine question but the RV has MORE than adequate performance...So much so I had to chuckle at the question.

Lets see cool morning with just me on boared...2600fpm at 250' MSL...never seen it lower than 2000FPM, then again I've never really looked at it above 5k.

Considering C152 Aerobats do what? 500fpm max (total guess) I don't think you'll have a problem...:)

Frank
 
I've done a few loops and similar "higher" g acro up to 10-12,000 msl and can't say I noticed a lot of difference. But I wasn't really paying that close of attention. Funny, because I do remember thinking that if I had a "structural problem", being at 10-12,000 MSL would be *really* bad! (Cause a structural problem at 25' agl will only barely kill you, right!)

I really think acro at MSL +3000 wouldn't be a significant negative, but would be something to keep in the back of your mind as you become more comfortable with your plane and it's handling characteristics. Just beware of the accelerated stall and possible subsequent spin. But that's the bottom line as I'm sure you know - you'll have to become comfortable with your plane at those altitudes.

As for a loss of power performance, the altitude wouldn't matter too much with my way of flying RV acro. I'm generally a low power RV acro flyer usually flying in the 50-65% power range.
 
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Depends

Hi Mike,
There's no easy answer since different guys with differing skill levels will do low acro when solo and higher acro with a passenger. Furthermore, rolls can be done a lot lower more safely than loops can. You don't say what your skill levels are either. A friend of mine has a low-altitude waiver and he does the whole shebang on the deck :eek: but that's his skill level.

If you're getting to know your RV, definitely use a safe altitude from which you can recover if you fall out of a maneuver (as in the top of a loop entered too slow). As Mel said, 3000 AGL would be a good place to start.

Regards,
 
I do all of my acro at 18" MP and 2500 RPM. That gives me about 140 mph indicated, about the same as I got in my Decathlon at 25 squared.

You don't need (or want) alot of power to do the appropriate aerobatics in this airplane. Power wide open on the downline can get a little hairy.
 
Thanks!

Thanks for the great replies. I really didn't expect the performance to be much of an issue and I'm happy to hear it's not.
I wasn't asking about AGL for safe acro, I'm sure that's different for everyone.

Most of my acro experience has been as a T-38 instructor in the air force (10,000' vertical required for a loop with a mil power, 500 KIAS entry & 5G pullup). Big differences between that and an RV, I think. :D
How much vertical is typically used in an RV loop?

Glad to hear that 6K - 10K' MSL acro won't suffer a big performance hit (vs 3000'MSL).

Thanks!
MikeJ
 
MikeJ 7A said:
How much vertical is typically used in an RV loop?
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I haven't specifically checked these numbers, but recall something like ~130-135 mph entry, 3-g pull and 400-500' altitude increase at the top.
 
Never paid that much attention to altitude gained, but I enter a loop at 140-150 mph IAS and pull maybe 2.5 or 3 Gs total.
 
How much vertical is typically used in an RV loop?[/

Well, you made me go out and check. Here's what I got:

Solo (200 lbs), 18 gallons of fuel, 3,000' msl, 70 deg F.

17" MP, 2500 RPM, 8.2 GPH.

3G pull at the bottom, .5G at the top, top of the loop was at 3600' MSL...a 600' loop.

My bill will be in the mail: 3.8 [email protected]= $11.32
 
Well Jim

Jim,
How long do you keep a plane? I am still flying the sweet RV-6 you sold me 2 years ago.
You have been in a Decathlon and a RV-4 since?
 
altitude

I had the good luck to get in on a conversation with Patty Wagstaff and some of her acro friends and I wrongly thought the limiting factor was airspeed. I asked Patty what her limiting airspeed was when she comes out the bottom of her vertical manuvers. She says "Airspeed, I dont even know what my airspeed is, I just look at the ground and when it gets close, I pull out."

I dont think Msl is a problem unless your at Denver. AGL is the most important limit. It may not be where you begin a manuver, but its where you end up coming out the bottom that seems to me the important thing. Your judgement in pull out is what will keep you alive. Knowing how much altitude loss you will normally expect for any given manuver is a good starting point. In spins I lose about 700 feet per rev in my cessna 140 so I never do them below 2000 agl. I dont lose any alt in a loop or a roll. Vertical manuvers are the most significant. Stalls and spins are vertical, expect to lose some alt in a hammerhead, but if you do a loop at the end youll get some of it back. You should study each manuver that you plan to do, and make sure you understand the dynamics completely before you try it. 4000 agl is a good place to begin the simple stuff like loops rolls and spins.
 
sportpilot said:
I dont think Msl is a problem unless your at Denver.
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Well, my house is at 6000'MSL so... this is why I asked the question. I won't be doing acro over my house, but still, my home field, Spearfish, SPF has an elevation of 3931' MSL. So my concern is acro in the 7-10K MSL range?

Mike
 
MikeJ 7A said:
...my home field, Spearfish, SPF has an elevation of 3931' MSL. So my concern is acro in the 7-10K MSL range?
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What's the concern? FWIW, 7-10K MSL is where I do my acro/spin practice 99% of the time. I love flying down low, but when I'm going end over end I like a lot of margin.
 
I believe several responding here aren't understanding the question. It's not whether or not there's adequate altitude margin below. It's what is the effect on the aircraft perfroming acro at higher altitudes. Will it snap out easier? Is there some special thing to note when loading the plane up at altitude?

I believe the answer is that there's not a lot of negative effect, or much noticable effect period, below ~10,000.
 
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I agree with Dan and Bryan - I did all of my acro testing in Phase 1 plenty high, and as long as I was below 10k, I felt no significant difference in the handling qualities of the airplane. I do most of mine between 5k and 8k probably.When you get up above 12-15k, you're going to start feeling the effects of altitude, and I generally like to just cruise up there.....but in any case, with an RV, there isn't much danger of Mach tuck!

Paul
 
markscogg said:
Jim,
How long do you keep a plane? I am still flying the sweet RV-6 you sold me 2 years ago.
You have been in a Decathlon and a RV-4 since?
Click to expand...

Hi Mark,

Good to hear from you, glad you are still happy with the -6.

I had the Decathlon until a couple of months ago. I did some aerobatic and tailwheel instruction in it over the last couple of years, but recently decided to get out of the instructing part and go back to "me" flying. Of course, you can't beat an RV, so I found a nice RV4 down here in Florida last October and bought it. Been having a blast with it.

I've made a couple of trips to Charlotte with it (Rock Hill, specifically), maybe next time maybe I'll stop over to Goose Creek and say hi.

See ya,
Jim
 
Low Pass said:
I believe several responding here aren't understanding the question. It's not whether or not there's adequate altitude margin below. It's what is the effect on the aircraft perfroming acro at higher altitudes. Will it snap out easier? Is there some special thing to note when loading the plane up at altitude?
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Yeah, the thing to note is...drum roll...LESS HP. That's it. Sure, TAS may be higher on the down lines than it would be down lower, flutter margin is reduced, etc. But if you're doing anything other than the sloppiest of acro, you shouldn't come anywhere near flutter margin airspeeds.

You'll have less vertical penetration at any power setting.
 
To jartlip

jartlip said:
Hi Mark,

Good to hear from you, glad you are still happy with the -6.

I had the Decathlon until a couple of months ago. I did some aerobatic and tailwheel instruction in it over the last couple of years, but recently decided to get out of the instructing part and go back to "me" flying. Of course, you can't beat an RV, so I found a nice RV4 down here in Florida last October and bought it. Been having a blast with it.

I've made a couple of trips to Charlotte with it (Rock Hill, specifically), maybe next time maybe I'll stop over to Goose Creek and say hi.

See ya,
Jim
Click to expand...

Jim,
Fly in season starts in a few weeks. Let me know when you are coming, I will tell you if there are any good ones scheduled.
Mark
 
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