[RVG8tor]

For those of you flying your aerobatic RVs, what is the max G you have pulled? I know doing maneuvers you will be in the 3-4 g range but what have you pulled either on purpose or recovering from a messed up maneuver. I am interested in that I would like to do some Basic Fighter Maneuvers (BFM) with my RV when it is finished and I am curious what the average G is. There is a video form yesterday or today of an RV-4 fighting a Glass Air. In the video it looks like the RV-4 was not putting his lift vector in lead enough and was giving away some nice guns shot for snap shots. My thought is he was not willing to pull the G required to get his nose in lead. I am sure others would like to hear the numbers. What I wonder is even though the airframe can handle 6g do pilots avoid this upper limit by a wide margin. The fighters I flew had G limits but we flew the plane to those limits. The airframe could handle more but the limit was there for fatigue life of the airframe, even still with age problems arose with wing spars. Thanks for the info

Cheers

 

[n5lp]

For those of you flying your aerobatic RVs, what is the max G you have pulled? I know doing maneuvers you will be in the 3-4 g range but what have you pulled either on purpose...

I pulled 6 during testing. It took me a few tries because the airplane bleeds speed quickly at high gee loading. I finally got there by flying a little inverted to keep the speed up.

 

[DanH]

Can't comment on the G's available, but I'll bet a bunch of us civilian pukes would like to read written descriptions of how to fly the Basic Fighter Manuevers.

 

[asav8tor]

I am unaware of a -4 or -6 wing spar failure. The rear -3 spar attch point issue has been addressed. The -8 main wing spar on the aircraft you are building is significantly different in that it's built from far fewer parts. New CNC machining enabled them to build a much cleaner, lighter, and in theory and static load test, strong enough spar.

What I have not seen discussed is the merits/disadvantages of mill steps in the new designs and the implications (single point failure). The second issue is the widespread lack of understanding (in the GA community) that the Gs you read on the G meter do not represent the Gs forces experienced in all areas of the aircraft in all situations (roll coupling or rolling G). None of this really matters much in that you can fly the RV quite aggressively in formation or aerobatics and pull no more than 3 or 4. But your question is max pull to the limit all the time. You will not find a consensus on that. If you want to fly that way I would limit the rolling G.

 

[frankh]

Max G

My Dynon G meter shows +5.0 and -2.3G...(The -2.3 was during an inverted spin attempt)

It is not necessary to pull 5G, I think that was when I screwed something up early in my practice..

I never see over 4 these days

 

[Mel]

Most I've seen on my -6 is +4.4, -1.

 

[RV8iator]

Second the response on the rolling G

Pulling G's while rolling is really important to understand. With the ailerons deflected and pulling 6 g's the real g-load on the outboard portion of the rising wing is greater. Never see much about this in civilian writings but it is a limiting factor on military airplanes.

 

[gasman]

AN AEROBATIC EPISTLE.......... by van

Can't comment on the G's available, but I'll bet a bunch of us civilian pukes would like to read written descriptions of how to fly the Basic Fighter Manuevers.

Dan... Look for the sixth and final issue 1998 of THE RVator, that I received on 2/4/99..
On page nine will get you started.

 

[Bugsy]

Lift Vector

I enjoyed watching the RV4 Dog fight but also noticed the lift vector lead turning every set up. Funny you said that because while my kid and I were sitting their I comented look where his lift vector is. Led to some high aspect engagements which just put the G load higher on later. I doubt youd have to max perform an RV to have some fun like in the video. I dont want to bend this thing just have some fun. Cool video, can't wait to give it a try.

By the way, who won those set-ups, the RV or Glassair?

 

[L'Avion]

Regularly pulling 5

As my G-meter doesn't record, checking with my formation mate (RV-4, N8DU, retractable gear), whom I regularly follow in some very interesting in-trail action, finds his G-meter recording +5 each episode.

Barney
N44LR, RV-4 flying
N234FT, RV-3 putting the wings back on

 

[RVG8tor]

Explanation of BFM

Can't comment on the G's available, but I'll bet a bunch of us civilian pukes would like to read written descriptions of how to fly the Basic Fighter Manuevers.

Dan,

I was going to try and make a long post on the subject but then found someone who has already done the work, being a fighter pilot I am not one to re-invent the wheel and this guy does a great job, the site is: http://www.voodoo.cz/falcon/AFT.html

So to do BFM in an RV one would have to determine its optimum turn radius, most setups would be based on this distance. A long range offensive set up would have the offender 1.5 times the radius at the start of the fight, intermediate right at the turn radius and close about .5 the radius, essentially the close set up is a guns exercise. One other thing is the best fighting speed, most airplanes have sweet spot where you can preserve a fair amount of energy without sacrificing much maneuverability. Sometimes referred to as corner velocity, it is the speed you can do your quickest tightest turn without taking the wings off. The sweet spot will be around this area. If you fly too fast you really have to pull the G to stay with you opponent, if you are too slow your rate of turn slows down, so even if he is on the other side of the circle he might eventually catch you. Hopefully some RV experts can give us some of the speed and 'G" that they find useful, I know there must be somebody doing some dogfighting out there. I know it is one of the things I hope to do when my RV is finished. I hope this and the site answers some of your questions.

Cheers

 

[osxuser]

FWIW, having flown more Glasair's than RV's, Glasairs bleed speed in turns REALLY quick, although the wing is something like +11G's. I know a 180HP RV-6 can easily take an 160HP Glasair I RG.... Turn radius is much tighter in the RV, and it doesn't bleed speed in the turn as fast or as much. The only thing the Glasair can do is tuck everything in and run.

 

[wera710]

BFM info

In addition to the comments above, you may also want to dig around for a book, first printed in 1981, by Frank J. O'Brien with Timothy R. V. Foster, Titled:

Every Man a Tiger, Mock-Combat Flying Techniques for Light Aircraft.

It was published by Zif-Davis Publishing Co./New York, ISBN 0-87165-076-2

It was my secret weapon back in the 80s when every sunday flight meant being jumped by local retired fighter pilots who loved to pick on the young guy in the Luscombe 8A. lol. It also seriously helped me hold my own and even whoop more than a few who, having flown big sleds in Nam, forgot some of the basics of the tight fight. I mean really, calling "Missile Missile Missle" two miles out (when you have none) ain't gonna buy you much when the kid in the Luscombe sucks you into a high speed yo-yo and comes down on your backside. hehe.

Man I miss them all. Great bunch of pilots, all passed on now.

Anyway, the book had quite a lot of interesting and useful information on maneuvers in light aircraft. It was written specifically for general aviaton pilots who wanted to go forth and have some fun. Thinking back on it, all of it would tranfer over to nicely our RVs. It certainly helped me against guys with 180HP screamers when all I had was a measly 65HP. They ended up playing the zoom and boom game after a while, cause even with the roll rate of a pig, the Luscombe could stick to their tail like glue in a turning fight.

 

[groucho]

My airplane hasn't complained up to 6g's. Like has already been said, basic acro can easily be done in the 3-4 range. BFM is a different story. I think it's worth putting a pad on the 6g limit if for nothing else because you can't stare at the G meter during BFM.

One thing to think about though...what's your plan if you see 6.1 (or 8.0) on your g meter? In-flight over-g actions/precautions and post-flight inspections are not something regularly talked about. If anyone plans on pushing it to the limit regularly, I bet it's worth talking with someone in the know on what to do when the limit's busted.

An over-g in a fighter squadron typically costs the offending pilot a big bottle of booze as a "donation" to the bar. What's the going rate for an RV over-g?

Turn in, fights on!

 

[tinman]

<snip>
An over-g in a fighter squadron typically costs the offending pilot a big bottle of booze as a "donation" to the bar. What's the going rate for an RV over-g?
<end snip>

Possibly $10K for a funeral???

 

[RVG8tor]

Harsh

<snip>
An over-g in a fighter squadron typically costs the offending pilot a big bottle of booze as a "donation" to the bar. What's the going rate for an RV over-g?
<end snip>

Possibly $10K for a funeral???

Wow me thinks Tinman might be afraid of the "G" (TIC).

As far as Groucho's comment with regard to over "G". At a minimum I would think doing a good inspection of the wing and tail surface connections would be warranted, if severe enough there would also be some deformation in the skins possibly. Perhaps some engineer type could tell us where the likely weak point is in this wing design, this could be highlighted as an initial inspection point.

I bought a bottle during my initial F-15 training, trying to bug out from a fight and did not have the separation, so when I pitched back into the fight doing 500+kts when Bitching Betty yelled "OVER G" oops.

I started this thread to get some info on what upper G was experienced, I conceded in the post that the typical RV does not fly much above the 3-4 G range. The F-15 had a 9 G limit but when fighting the jet you were typically in the 5-6 G range as long as you were not trying to defend against a shot. For me this thread was more about getting some confidence in the design limit, if a fair number of RVs have flow to this limit with no trouble then my confidence builds. If a few have flow over the limit and had no problems then the confidence gets even better. Since it is a 6 G airframe with a 9 G tested failure point, 5 to 5.5 G should be a nice limit for the life of the airframe. Thanks for all the posts and keep them coming, I really want to hear from the guys that really scared themselves. Don't be shy, we all learn from the stories. Every pilot out there has a story of something that scared the heck out of them.

Cheers

 

[tinman]

Nemo is correct...Tinman is afraid of the G's.

My -8 is not flying, so my experience is only with the rental crates. I am looking forward to expanding my flying horizons once the RV is up. I feel that I can trust the RV a bit more than the C-152. A few years ago, I was flying along in the trusty Cessna when I looked down and could see another shadow behind my aircraft's shadow. Being somewhat astute, I reasoned that I was not alone up there...

Looking behind me, I saw a beautiful A-10 Hog who wanted to play...I wagged my wings and pulled it into a tight turn and the Hog had to overshoot. He couldn't hang in there as tight and slow as I was in the Cessna. I was playing a looser's game since he had the gun and I had no ability to work the vertical dimension with the Cessna... the Hog reversed and made another run on me from behind. I was having the time of my life! Then I heard a big "crack" and the wing tore off from the top of the cabin...ok I made that part up

It was great fun to mix it up with the other plane for a bit and I look forward to hear more about how the RV tolerates G loading as this thread continues. I am curious about what the above engagement would have looked like on the FAA's atc scope. I was at least 25 miles away from any controlled airport, but had the xpdr on. Would they have witness a "merge"?

 

[DanH]

Mike,
Thanks for the F-16 link. The only (very informal) ACM I've had was from one of your F15 brethren who based with us for a while. I fixed his biplane in trade for some acro and dogfight instruction. First thing I learned is that the pros fight with their brains.

Scott,
Thanks for the book citation. I'll find it. I note your handle (wera710); what are you racing?

 

[groucho]

I bought a bottle during my initial F-15 training, trying to bug out from a fight and did not have the separation, so when I pitched back into the fight doing 500+kts when Bitching Betty yelled "OVER G" oops.

Hehe..."Cylon 1's out north...%$*&!! Cylon 1's in from the north!" Yup, I've bought my share of bottles for the bar too. We had a dude that did -5.5g gun jink back at Eglin (-3g limit..ouch). We named him Jinx. (now a weapon's officer)

Back to RVs...I've been to 6 in my -6, but not over. If the design margin is 1.5, then things should start to permanently bend at 9. Things will break off somewhere above that. If you keep your g's under 5.5 or so, you should be way fat on the safety margin. You may, however, see a decreased engine and/or prop life if you're there regularly (as compared to a 1g guy).

 

[4kilo]

Important Correction

It is worth noting that if the airplane is stressed to +6 (even with a 50% safety margin), then it is permitted to bend permanently at 6.1. It only has to withstand +9 once to satisfy the engineering requirements.

To paraphrase the requirements, the aircraft must withstand its load limit without structural DAMAGE, it must withstand 150% of the load limit without structural FAILURE.

Pat

 

[groucho]

To paraphrase the requirements, the aircraft must withstand its load limit without structural DAMAGE, it must withstand 150% of the load limit without structural FAILURE.

True & good point. It'd be nice to know what the design margin was on the damage portion of that in the RVs. If it's designed to damage at 6.1g's, then, well, that's a little more scary.

6061-T6 yields around 35kpsi & has an ultimate strength around 42kpsi. If that's the spar, then the failure & damage points should be closer together than 6 & 9g's. So...if failure occurs at 9, damage shouldn't occur until a good margin past 6. There are lots of other parts in there though.

How about this: Lets all stay below the g limits for our aircraft & configuration. RVs have a good history of staying together. Lets keep it that way!

Fly safe!