What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Loop Speed

Status
Not open for further replies.

GHARBEN

Active Member
When I first started flying the RV 4, I read about a max speed at the top of the loop to prevent over speeding in the pull out. Does anyone know that speed?
Thanks
G Harben
N12HR O320
 
There is no such thing as being too fast on top of a loop. Physics dictates that if you complete a 1/2 loop at a constant power setting within the airplane's airspeed and G limits, then you will be capable of completing the 2nd half of the loop within those same limits regardless of your speed over the top. Aerobatic training will clarify this issue.
 
My friend tells me that in his RV-8, if he's above 80kts as he goes over the top, he'll just push and roll out of it. I suspect he's very conservative.
 
I look at my entry speed. At the top, I’m looking outside to make sure I’m on a straight line. I don’t think I’ve ever looked at my speed while on top.
 
There is no such thing as being too fast on top of a loop. Physics dictates that if you complete a 1/2 loop at a constant power setting within the airplane's airspeed and G limits, then you will be capable of completing the 2nd half of the loop within those same limits regardless of your speed over the top. Aerobatic training will clarify this issue.

That makes a lot of sense. I thought the same thing as the OP but the physics potential energy thing make sense
 
I certainly appreciate everyone’s information. Perhaps what I remember was referring to the RV 8.
This leads to another question.
Does is follow that the “G” force of the pull up into the loop will closely match on the “G” force pulling out at the end of the loop?
G Harben
N12HR. O 320
 
Loop

That only applies if the second half of the loop is reasonably close in size to the first half. If you ease off on the G load, especially in the last quarter, the speed can get out of control in a hurry.
The key is to enter and exit the loop at exactly the same altitude. if you do that the exact shape of the loop and the speed across the top is not a big issue.
I did a lot of loops in the Glasair I with no inverted fuel system. I modified the top of the loop to keep a bit of positive G so the engine was happy. Entry at x altitude at y speed, full throttle all the way. Finish at x altitude airspeed will be y. Finish 100' low you will be going faster than entry.
One of the biggest dangers in self taught aerobatics is a simple aileron roll. Get lost at inverted, pull thru in a half loop and forget to close the throttle and you will likely exceed red line.
Van's dissertation on aerobatics in RV talks about how easy it would be to see 20 G in that or similar situations. Of course at 20 G many parts would be long gone. That is exactly what happened to the RV7 near Atlantic City.
 
I agree with Rick not only in theory but it also matched my experience. If you fly a reasonably round loop there is no reason to pull any power anywhere and you will end with roughly the speed you started with. For sure in an RV-8 and I am told that's true for a 4 too.

Where it becomes more tricky is if your loop is not round. If you never got anybody looking at your loop from the outside and critique you I nearly guarantee that your loop is not round. It is likely L shaped or even worse an L closing low (not sure what letter that would be). If you do fly a low L you certainly can overspeed your RV in what you might think is a loop.

You will pull roughly the same G on the exit and entry of a round loop so if you don't that's a first indication that its not round and the "you can't overspeed" statement does not hold.

In general Gs are your friend in an RV (within G limits of course). Use them early if you are in trouble. The wing geometry RVs have generate a huge amount of drag at high Gs so it will help you get any overspeed under control. If you try to recover "gently" you will go from bad to worse as you keep gaining energy you need to get rid of... .

Hope that helps.

Oliver
 
Van's dissertation on aerobatics in RV talks about how easy it would be to see 20 G in that or similar situations. Of course at 20 G many parts would be long gone. That is exactly what happened to the RV7 near Atlantic City.

One thing I noticed is that people which never rolled an airplane before tend to stop rolling or slow their roll when inverted. I have observed that more than once not quite sure why. If you do that the natural tendency is to pull gently to generate positive Gs. That's exactly the opposite of what you should do (push and role)... and if you entered the roll at cruse speed -- which is common -- you will WAY overspeed your airplane.

Oliver
 
Aerobatic training will clarify this issue.

Some dual aerobatic training with a good instructor is a really great use of a few dollars. If you are in Georgia, Florida is not that far. Allan at Patty Wagstaff's school has a bunch of RV time.
 
Speed

You can overspeed the plane, prop or both.
With a fixed pitch prop you need to pay a bit more attention.

You can also find yourself slow and stalled at the top of a loop, if you find yourself in an inverted stall your might be a bit surprised

Get some training before going and leaning on your own. Aerobatics can be extremely fun.....but you can also ruin your seat pad!
 
Careful what information you ask for on the internet...

There is no such thing as being too fast on top of a loop.

This is ONLY true provided it's flown as a round loop, (which you do allude to) and initial stick pull force (resulting G forces) are the same as the exit stick pull force (and resulting G force). The alternate is pulling hard at the beginning (resulting in higher airspeed over the top) and lazily pulling on the back side. Now you're easily "too fast" over the top for that type of loop. Airplanes have a lot of gray areas...

Also, GHARBEN, not to be rude and assume, but based on previous postings, you're new to the RV-4? RVs in general? I dont' know your aerobatic background, but if it is minimal, PLEASE find someone knowledgeable near you and get some instruction prior to venturing too far on your own in a new airplane. That's when the holes in the swiss cheese model line up, my friend.

This discussion would benefit from some specifics. This by no means intended to be instructional information. Just clarifying what others have added. There are MANY ways to "loop" and airplane... some better than others.

A perfect, round loop begins and ends with the airspeed, altitude, and heading exactly the same, making a perfect vertical circle in the sky. To do this, you must pull the same G forces in the first quarter of the loop as the last quarter of the loop. Your stick position and pull forces should constantly be changing with regards to airspeed.

Relax the G forces too early, and you create and "egg shaped" loop by adding too much vertical component, too low airspeed, and sometimes "flopping" over the top. Correctable by delaying your recovery pull and then you might end up on airspeed and altitude. Correct results, poor execution.

Fail to relax the G forces on the upward portion of the loop and you've tightened it too much. Results would be excess airspeed and not enough vertical component. Correctable by pulling the same excess G forces earlier than normal and ending on the correct airspeed and altitude. Again, correct results, poor execution.

Another thing to address is the idea of the physics. In a perfect world, yes... No need to touch the throttle. Energy removed by gravity going up the loop is added again on the backside of the loop. But we have propellors producing thrust. Whats happening is the engine and prop are fighting gravity on the way up creating a higher potential energy (read: Altitude) than would have otherwise happened in a glider. The same occurs but in reverse on the backside. The engine/prop combo is ADDING energy to the already higher potential energy (read: altitude) on the way down creating MORE kinetic energy than you started with (read: airspeed).

Bottom line? You must pull the power back to make a perfectly round loop and come out on airspeed. RV's (as we know) are slippery and build up airspeed very fast when Gravity assists.
Alternatives to pulling the power? Pull harder on the backside of the loop to keep the radius... Not my first choice, especially if you were fast at the top to begin with.

So to finally SIMPLY answer the OP's question, you CAN be too fast on the top of a loop (or any vertical maneuver) if you don't recover correctly.

My personal max in my 160hp, FP, RV-4 are about 100mph over the top. That is for any vertical maneuver. Split S' also come to mind. If I see 110mph while inverted and beginning to pull, I know I should onset the G's sooner than later or else it will be VERY fast coming out of the bottom.

It should also be noted that these are for 3-3.5G maneuvers. You can pull up to 6G and that will bleed the gravitational energy faster (load up the wing and manage airspeed), no doubt. But I personally don't fly that hard in my -4.

Comments such as "no such thing as too fast on the top of a loop" are dangerous things to suggest with an already slippery airplane. Reference: Smoky's story about Vne being TAS versus IAS. I digress... Please, manage your energies well and keep it within the limits, friends.
 
Last edited:
I certainly appreciate everyone’s expert advice. All my aerobatic experience is in very slow aircraft. I normally fly a series of hammerhead stalls until they become comfortable. Then pull the stick back and loop the aircraft. I have a lot to learn about the RV. Sounds like a little help would be well advised.
Thanks to everyone!
G Harben
 
This is ONLY true provided it's flown as a round loop

No, not just true of round loops. It doesn't matter how round or egg-shaped you fly the 1st half of the loop, as long as you don't add power on the way down, physics still dictates that you have the CAPABILITY to fly the 2nd half of the loop within the same G/airspeed limits you flew the 1st half. If you end up over speed/G pulling out, it's not because you flew egg-shaped or too fast over the top, it's because you mismanaged the energy on the way down. Mismanaging energy is a separate topic. The OP asked about a speed that's too fast over the top. It just doesn't exist, whether you're flying a J-3 or a jet.

Comments such as "no such thing as too fast on the top of a loop" are dangerous things to suggest with an already slippery airplane.

I disagree. I've provided plenty of training in the acro community and am sensitive to newbie issues. We are talking a matter of physics here. Nobody overstresses their airplane because they were too fast over the top of a loop. This is not a direct cause of newbie acro accidents. Good aerobatic training eliminates the need to even think about this question. It just doesn't apply.
 
Last edited:
Mismanaging energy is a separate topic. The OP asked about a speed that's too fast over the top.

Aerobatics IS energy management! Flying is energy management! Airspeed is a quick (but not perfect) indicator of energy state. If I'm wrong, then my almost 10k hours of flying time has all been done incorrectly!

The quick and dirty example is rolling inverted at 210mph TAS and pulling. MAYBE if you go right to 6G's, you can keep the airspeed in check. I personally have never tried that in my RV.


Nobody overstresses their airplane because they were too fast over the top of a loop.

I believe we're talking about the same thing but, I think you're assuming correct stick pressures are applied and a proper maneuver is flown. I assume nothing. It's the internet, you don't know anyone's experience/reactions/skill set. Much like I don't know yours and you don't know mine.

Simply, if you have gotten yourself inverted by starting a Loop (not assuming split-s, so assume you're not a redline airspeed), AND intend to complete the loop, AND you pull hard enough to finish the loop, AND aren't trying for a perfect altitude and airspeed to finish, then yes! I agree, you can't be too fast.

But to generically throw out on the internet for those with less experience than yourself that "you can't be too fast" just makes my hair stand up a bit. You certainly can, and there are stories of tails fluttering and coming off to prove it.
 
The quick and dirty example is rolling inverted at 210mph TAS and pulling. MAYBE if you go right to 6G's, you can keep the airspeed in check. I personally have never tried that in my RV.

If your RV can achieve 210mph on top of a loop, name your price for your airplane and I'll buy it. :)

But to generically throw out on the internet for those with less experience than yourself that "you can't be too fast" just makes my hair stand up a bit. You certainly can, and there are stories of tails fluttering and coming off to prove it.

All I'm saying is that we're inventing a problem that doesn't exist in the aerobatic world. Teaching an aerobatic student to be careful about excess speed on top of a loop is not a thing. This is not how energy management is taught.

Get good training folks, that's it.
 
He did not say he was doing 210 at the top of a loop. He said roll inverted at 210 and that is very easy to do.

You missed the sarcasm in there. :) What does rolling inverted at 210 have to do with looping? I think the OP’s question has been fully covered here.
 
If you are flying aerobatics properly no one who knows what they are doing is looking at their airspeed at the top of a loop. They have their eyes outside of the cockpit pretty much all of the time. The first time you watch airspeed is the prior to entry, once you enter the loop your eyes should be on the wing tips, then as you enter inverted flight heads up to stay on line...usually some right rudder is needed to keep on line over the top as you relax the back stick just a bit letting it fly of the top and then back stick to finish the loop. A nice round loop needs about 4 G's and a gentleman's loop about 3- 3-1/2 G's. There is not much difference in slower planes like a Citabria compared to an RV. If you can fly aerobatics properly in one you can fly them in the other. Go and get some proper training and you won't be asking questions like this.:)
 
In an RV-8 you will fly a perfectly round loop with a 4.5g initial pull same entry/exit speed no over RPM on a fixed pitch prop under full power all the way around. Have had ground judges confirm that many times ( I am not saying I can do that every time … not that good).


As for physics. Under full power at maneuver speed most RVs gain energy/speed. So even in a round loop under full power you would gain a little speed by the time you are done depending if you would have gained speed in leveled flight. Pulling 4.5g generates enough additional drag to remove that excess energy. If you pull less and fly a perfectly round loop you will likely gain a couple of knots but it shouldn’t be drastic. Somewhat less speed then you would have gained at full power at leveled flight.

As said before the biggest issue when you get started is that you will have no idea if your loop was round and if it isn’t you can overspeed and break the airplane.

Oliver
 
NATIONAL AEROBATICS DAY CELEBRATIONS!

You don't have to be an IAC member to attend one of these events. Getting free expert, in person instruction trumps internet advice on learning aerobatics any day. You can find a contact for the nearest IAC chapter HERE. Direct links to posted chapter event details are HERE. The IAC isn't just about competition. Only 11% of the membership are active competitors. The remaining 89% are pilots just like you!

Celebrate aerobatic flight on Saturday, June 26, during the inaugural National Aerobatics Day!

National Aerobatics Day is the perfect day to host an aerobatic camp, a BBQ, a practice session, or to share videos of aerobatic activity online. With over 40 chapters nationwide and two international chapters, IAC members are organizing these types of activities and others to engage the public and general aviation pilots in aerobatics.

CHECK OUT the Upcoming IAC National Aerobatics Day Events

IAC 3 - Meet and Greet, Williamson, Georgia (GA2) : LINK

IAC 11 - Community BBQ, Warrenton, Virginia (KHWY) : LINK

IAC 26 - Practice Day, Lancaster, California (KWJF) : LINK

IAC 27 - Practice Day, Jackson, TN (KMKL) : LINK

IAC 34 - Practice Day, Bellefontaine, Ohio (KEDJ) : LINK(link is external)

IAC 35 - Practice Day and BBQ, Concord New Hampshire (KCON) LINK

IAC 52 - Practice Day, Bayville, News Jersey (KMJX): LINK

IAC 58 - Practice Days and Open House, Tunkhannock, PA (76N) LINK

IAC 77 - Apple Cup Aerobatic Competition, Ephrata, WA (KEPH) LINK

IAC 80 - Midwest Aerobatic Championships, Seward, NE (KSWT): LINK

IAC 88 - Presentation and Static Display, Ray, Michigan (D98:) LINK

IAC 119 - Open House and Burger Burn. Augusta, Kansas (3AU) : LINK

IAC 133 - Practice Day, Chesapeake, Virginia (KPVG): LINK
 
Celebrate aerobatic flight on Saturday, June 26, during the inaugural National Aerobatics Day!

FYI, Patty is also holding one at 42J in FL:

National Aerobatics Day

Akro Fun and Cookout
June 26, 2021

Keystone Heights, FL (42J)

Cookout 10-2, Box open 10- 5

Let’s Celebrate National Aerobatics Day !
The box is open!
Hosted by PWAS, Chefpitts, Nikolai Timofeev, and Keystone Heights Airport
Free Coaching, Lots of akro, fun and food with friends !
$50 Donation requested to benefit IAC.
PLEASE. RSVP by June 18 for catering: pattyaerobatics@g m_a_i_l.com! <fix it>
 
I have a max entry speed

Some dual aerobatic training with a good instructor is a really great use of a few dollars. If you are in Georgia, Florida is not that far. Allan at Patty Wagstaff's school has a bunch of RV time.

Just me,
But I have a set max for entry speed of 135 (mph).
Things can get rough if you combine maneuvers prior to the loop.

I may be conservative, but I'll take it.

As for speed at the top, I never looked. I was trying to make a circle, not a script oval.

I pull the g-'s I want at altitude to begin the maneuver.

Daddyman
 
STOP!

Just me,
But I have a set max for entry speed of 135 (mph).
Things can get rough if you combine maneuvers prior to the loop.

I may be conservative, but I'll take it.

As for speed at the top, I never looked. I was trying to make a circle, not a script oval.

I pull the g-'s I want at altitude to begin the maneuver.

Daddyman

This is the sort of information you will get when you learn aerobatics from the internet. A loop entry speed of 135 MPH is DANGEROUS! Get aerobatic instruction from qualified instructors. Your nearest IAC chapter can point you in the right direction.
 
As for speed at the top, I never looked. I was trying to make a circle, not a script oval.

135mph is too slow, but be aware that EVERYONE flies extreme oval-shaped loops until they get ground coaching. Everyone severely underestimates the initial G-pull required as well as the amount of time required spent floating over the top with a tiny pitch rate in order to fly an actual round loop. Dust and dirt will float off the floorboards the first time you do it correctly. What "feels" round is nowhere close. For such a "simple" maneuver it is one of the hardest figures to self-critique from inside the airplane. Just another excuse to hook up with your local acro crowd and make new friends and improve your flying. :)
 
Loop

This is the sort of information you will get when you learn aerobatics from the internet. A loop entry speed of 135 MPH is DANGEROUS! Get aerobatic instruction from qualified instructors. Your nearest IAC chapter can point you in the right direction.
A ray of sunshine on a very cloudy day. Ron is EXACTLY RIGHT. An absurd number of posts on here from people who don't know what they are doing, mixed in with a few who give excellent advice.
 
Aerobatics

A REALTY CHECK; Find and study the accident report on the fatal RV accident near Atlantic City, NJ. Hopefully this will change your mind about self taught aerobatics, especially in airplanes where rapid speed increase is more likely.
I have posted this before but many years ago I provided aerobatic instruction to a gentleman who admitted to near 300 m/h, probably way to many G's and VERY close to the ground in an RV6. Attempting to self instruct aileron rolls, same as the Atlantic City accident. After he regained his composure he called me and booked some instruction in the Pitts S2B.
 
My personal technique which has always served me well and kept me out of trouble - no panic situations at the top of the loop or overspeed concerns at the bottom of the loop:

Start at 170 MPH indicated, nice pull with full power to about 3 gs. Coming up over the top I relax pressure a bit (back to about 1g or so), then as the airpseed starts to increase when going back downhill, go to idle power and start transitioning back to about 3gs. I usually crosscheck my speed at the top and look for 70-80 mph indicated. If slower than 70 I don't demand much of the airplane (little less pull), if above 80, I pull a little more to avoid getting too fast.

Seems to me there are two spots to get into trouble for a newbie. Too much pull when slow at the top (resulting in a stall), or not enough pull at the bottom which could result in an overspeed.

This will not be a competition perfect round loop, but more of an egg shaped loop, but if flying for fun, who cares? I'd start with the egg shape then transition to a round shape over time (if that's your goal).

I have a carb'd RV-4 with no inverted fuel or oil, and a slick fixed pitch Sensenich GA prop. Much easier if you have a C/S prop IMHO.
 
Enough!

Here's my personal technique. I'm not going to add my "technique" to this thread and I'm appealing to a moderator to put an end to this. There are many experienced aerobatic pilots who have put some good information out here but there are others who have put out some pretty dangerous information. The problem is that someone new to aerobatics doesn't know which is which and there is a good possibility that an inexperienced pilot will unknowingly follow the wrong advice and get into serious trouble.

So I appeal to you inexperienced pilots again... Get instruction from a qualified, experienced aerobatic instructor. Seek out an IAC chapter and get tons of free advice from those who know aerobatics or find an aerobatic school. Instruction in certified aerobatic airplanes such as Decathlons or Extras translates easily to your RV. The basics are the same in most all aerobatic airplanes.
 
Yes and this talk of going to idle power on the back of a loop is what people do when they are teaching themselves aerobatics and/or don't know what they are doing. Let's please not do this. Get decent training.
 
Status
Not open for further replies.
Back
Top