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RV tip over (flip upside down)

My question to you JOHN is, if you knew that the statement was Horrible, why did say it? That's just wrong. This by far has been one of the most offensive thing I have heard on this Board. One good thing about your post was that it adds your name to my list of people I don't read post's from.

Thanks

Richard
Slinger, WI
RV7A
 
Every two years, I have to go to one of my local airports to get a BFR. I usually 'scout' the flight schools, both for equipment and instructors before I make an appointment.
Can't do much about prices.

I try to enlist the services of the oldest CFI I can find. The past 3 BFR's I have not been able to get anyone over 25.

I have found that the current crop of CFI's are poorly skilled in teaching proper landing technique. They do just fine until the wheels touch down. Then it goes bad.
I have not had one CFI correct me for NOT holding it off. I purposely let it down early on a couple of landings to see if they would notice. The words I heard the most were 'Good Job'. On one landing last BFR, the CFI seemed to get a bit anxious about how long the nosewheel was not on the ground.

Later, if everyone wants, we can get into the 'slam on the brakes so we can make the first turnoff' school of flight instruction.

This is the kind of stuff that leads to bad landing technique by the 'average joe' pilot. This is what causes many landing accidents.

Greg Piney
RV-8 (not -A) Gonnabe
Setting up shop
 
Honesty is best!

jcoloccia said:
I couldn't agree more. I would now like to change my position to:

I know this is going to sound horrible, but I just can't get rid of this feeling that the -A's somehow "deserve" to nose over because they're so ugly.


edit: I can't believe I even have to but this in here. This is meant to be lighthearted. If you read my earlier posts you'll see I was contemplating an 8A and have nothing against trikes.....except that they're ugly, of course :)
Click to expand...
I admire your honesty, John. And agree that the trikes are pretty ugly until faired up. Then they look like those little spaceships from the cartoon "Jetsons". But, I still like mine and wouldn't trade it for anything... except maybe a tricycle P-51.

p.s. I'll taxi behind you at a fly-in and talk you down the taxiway, since you won't be able to see in front while dragging the tail. ;)
 
redbeardmark said:
And, hey, you fence-sitters... pick a side and get with it.
Click to expand...

I've been following the discussion here with interest even though I'm probably a few years away from becoming a builder. Oddly, this discussion is making me question my initial choice of a TW airplane. I've got somewhere around 1500 hours with about 1000 in TW airplanes and of that about 800 or so is off of grass. So obviously I'm very comfortable in TW airplanes and therefore my only concern was which non-A model to build. But the discussions here have got me thinking. None of the TW airplanes I've flown had wheel pants and I while I'd probably base the plane at a paved airport, I'd want the option of basing or operating on grass.


Now that I think about it, I think I'd be just as nervous taking a TW RV into certain strips as I would be taking an -A. Unless someone else with wheel pants has landed before you recently, you can't really know if the pants are going to pack up with grass/dirt until you land and if they decide to pack, you're most likely going over.

From what I've read here, it comes down to picking your poison. The -A model nose gear seems to be somewhat of a weak link (though all nose gear are to some extent), but the TW gear with those wheel pants and small tires don't seem exactly rough strip friendly. So do you want to fly an airplane that can bite you if you land with poor technique or pick the wrong spot to land on (-A model), or do you want to fly an airplane that can bite you if you land with poor technique or if you pick wrong spot to land on (TW model)?

Either way it seems as other have said, these are not your father's 172s and they require you bring your skills up to the task of handling their performance.

Now I've just got to find that job that nets us and extra $30K a year and gives me 30 or 40 extra hours a week to build. ;)

-Cheers
Joe
RV? -Pre preplaning
 
ship said:
.

start soapbox
This is all much ado about nothing. Trikes AND taildraggers from ALL manufacturers ALL flip under the right circumstances.
Click to expand...


If this is all "much ado about nothing" then why did Van the man redesign the nosewheel on the RV7A earlier this year. Presumably he was a little uneasy about the design. Correct me if I'm wrong but I suspect that if Van himself was a little uneasy about the nosegear stability then others may also be justified in having some concerns.

Incidentally, this is the wrong forum for this thread. It's a serious matter and having it in the "Nosewheel vs Taildragger" forum trivialises it and invites both adversarial and defensive comments that shed no light on the topic.
 
Maybe Van's is more uneasy about some of the people flying the "A" models than the nosegear, itself. That's probably why Van's recommends good transition training and good technique.

JMHO

Roberta
 
Quote:
Originally Posted by Bob Collins
I would think the tiedown ring would serve that purpose, wouldn't it?


The tie down ring should protect your tail if you manage to get the nose that high at touchdown. You can push the tail down and see if the tie down ring contacts before the tail--if it doesn't, make an adjustment to the depth that the tie down ring is screwed in.

redbeardmark
Click to expand...
Be careful using the tail tie down ring as a "curb-feeler". I took the following pictures of two 6A's at Land of Enchantment. The aircraft were parked side by side, so it was easy to compare. First is the "normal" tail tie down ring:

img07737uj.jpg

And next a tie down ring that has been "adjusted" (bent backwards) by what most who saw it agreed was an overzealous attempt to keep the nose high at some time in the past:

img07727no.jpg

As redbeardmark said later in his post:
Again, if the nose is that high, things are going wrong.
Click to expand...
"Let's be careful out there..."
 
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jcoloccia said:
Ah, nevermind....

L.Adamson RV6A (cause it looks better on the ground)

edit: I see that the poster originally contemplated an 8A. IMO, the "8" looks better! Most tandems should be taildraggers.... period!
Click to expand...
 
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damaged tie down rings

I don't know for sure, but if you step up on the steps with a passenger-- the tail is going to slam into the pavement, as I watched in horror the first time I saw it happen.

after so many of those-- the bar tail ring could cause fractures; the treaded areas inside the tail, right?
 
robertahegy said:
Maybe Van's is more uneasy about some of the people flying the "A" models than the nosegear, itself. That's probably why Van's recommends good transition training and good technique.

JMHO

Roberta
Click to expand...


I doubt it's all that complicated. Van is obviously concerned about RVAs ending upside down and the effect that this will eventually have on corporate sales if it continues. In his wisdom he decided that it would be more productive to redesign the nosegear to provide a greater safety margin than to get down on his knees and pray for all RV pilots to have greatly improved flying skills.
 
Had to see it for myself

After looking through the NTSB database searching the "A" models here are the results.

RV-6A 37 records 16 flip overs 2 nosewheel colapses w/o flipping

RV-7A 4 records 3 flip overs

RV-8A 5 records 3 flip overs

RV-9A 6 records 4 flip overs

After reading the accident records it seemed like there were a large number of the flips that happened after bouncing the airplane in hard and when it started flying again making the decision to continue the landing and not going around. There were several weird ones like a headset under the rudder pedal that caused the plane to veer off of the runway and flip. It looks like if you end up in the NTSB database for some kind of accident while flying an "A" model you have a 50% chance that your airplane will have gone upside down. Of the 52 total records on file for all "A" models there are 26 RV's with their feet up when they came to rest.

This kind of makes transition training and the perfection of the soft field technique seem extremely important.

Regards,

Bryan 9A "Flyin The Flag"
 
Stats?

Are all the cases in the FAA data base? Some go un-reported. The RV-7A taxi case around Oshkosh time is not in there?

I read a few of the narrative of flips, many are clearly and obvious landing, control problems or forced landings off airport. However it is the few that seemed to happen under normal conditions, or at least reported normal conditions. Some of these are not in the stats, I think. However thanks for taking the time to review the data; we can always learn something, but it is hard to draw any solid conclusion from the raw data. However your suggestion to get trainning is well taken. George
 
"And next a tie down ring that has been "adjusted" (bent backwards) by what most who saw it agreed was an overzealous attempt to keep the nose high at some time in the past:"

I think that's a bit harsh! I have arrived tail first a couple of times, and its not that difficult to do until you have a few hours on type. Typically landing in a gusty crosswind is the scenario. My approach speed is arround 80 mph 2 up. If I get slightly slow (say 75 mph), and then the gust stops near the ground, the only way to stop the sink rate is with increased attitude (there's plenty available before the stall). Sometimes you get away with it, sometimes you bash the tail. Sounds horrible but usually there's no physical damage. The key is accurate speed control on final, but I'm sure that I'm not the first person to discover that!

My tie down ring is welded to a piece of steel and bolted to the fin post, I do have a strip of aluminum under the ring also. Apologies for the poor picture, its the only one I have - boxes were to keep the tail off the floor while the engine was out (didn't work as it fell off while pushing around and broke the rudder fairing :( )
tailbumper18pj.jpg


Pete
RV-6A
 
I agree

gmcjetpilot said:
Are all the cases in the FAA data base? Some go un-reported. The RV-7A taxi case around Oshkosh time is not in there?

I read a few of the narrative of flips, many are clearly and obvious landing, control problems or forced landings off airport. However it is the few that seemed to happen under normal conditions, or at least reported normal conditions. Some of these are not in the stats, I think. However thanks for taking the time to review the data; we can always learn something, but it is hard to draw any solid conclusion from the raw data. However your suggestion to get trainning is well taken. George
Click to expand...
I agree wholeheartedly with the last sentence regarding training. It is not surprising that "many are clearly and obvious landing, control problems or forced landings off airport". If we subtract those from the total number of flips, do we arrive at a very small number of inexplicable flipovers?

However, I cannot agree with any analysis, conjecture, or theories regarding any tendency to flipover based upon anecdotal evidence that "are not in the stats". Think about it for a minute: if a supposition is made that the A models are prone to flip over, and the supposition is based upon anecdotal evidence possessed only by those who make this supposition, is this being scientific or logical? Are we learning anything or simply being influenced?
 
"And next a tie down ring that has been "adjusted" (bent backwards) by what most who saw it agreed was an overzealous attempt to keep the nose high at some time in the past:"

I think that's a bit harsh! I have arrived tail first a couple of times, and its not that difficult to do until you have a few hours on type.

Pete
RV-6A
Click to expand...
Pete,
I'm not passing judgement, just reporting what I heard. I was one of 7 people in the discussion, including the owner of the airplane (who was not the original builder). Of these, 5 were RV-6A owners...including Gary Zilik and Paul Rosales. What I wrote was the concensus opinion of these experienced people. I'm sorry if you think that's harsh.

Best,
 
Rear Tie Down Ring

George Orndorff sells a stronger and safer system for the rear tie down ring.

With this system the tie down ring can be unscrewed like those used on the wings.

He moves the attachment further forward and bolts it to a bulkhead hence even if you don't remove the tie down ring it can't catch the rudder and affect rudder movement.

Here is the link http://www.fly-gbi.com/aircraftparts.htm

Barry
 
Taxi problem today

Well, here I sit humbled and deeply embarrassed. Last night at around this time I was sitting here in this same chair going over NTSB records for "A" models and trying to learn more about the nosewheel flips and how to prevent them. Here I sit tonight with my nose wheel fairing, nose gear leg fairing, and pride hurt. This is not supposition, speculation, or anything other than just sickening to me. Today I landed at Frazier Lake Airpark near Hollister, CA where I have landed probably 100 or so times before because it was my home airport where I did my first flights and flew off all of my time during phase one. We then kept the plane there another six months or so before moving it to where it is now. Frazier Lake is a very nice grass runway that is a joy to land on. With the nose over debate so fresh in my mind I was very careful to do a textbook soft field landing and it went just as planned. The transition from the grass to the paved taxi way is smooth and was a non event. Getting down to the the transient area there were a group of pilots waiting and greeting arrivals for the first Saturday of the month fly in. I made the transition off of the paved taxiway to the parking area which is dead grass that is very short and the dirt under it is very hard packed. I stopped and thought about shutting down and pulling the plane by hand the last little bit and decided that this would be no problem. The stick was full back and the plane was doing great. I had about 40 feet to go with a 90 degree turn to the right to park in line next to the plane on the end. My eyes locked onto the little mound of soft dirt that looked like a gopher had been working in the area. Veering slightly to the right to miss this soft spot I felt a soft bump and that was it. I pulled forward and shut down. After double checking that the mags were off, keys out, master off I looked up and saw the group standing 20-30 feet were extremely interested in my airplane. One came over and started checking the prop to see if it had struck the ground, several heads were inches above ground level looking at the wheel pant and the sick feeling started to set in. I was told that my nose gear had bent back and they all thought that it was going all the way under. This can't be! The bump felt so small and the speed couldn't have been over 2mph. The cowl didn't dip noticably, and there was no sound inside that would warn of such a problem. The nut on the bottom of the gear leg tried to exit the bottom of the front half of the wheel pant. The scuff on the wheel pant front shows that the nut was working its way to digging into the dirt, but there was not enough energy to finish the job from the looks. The main mounts on the inside of the rear half of the wheel pant where the axle goes through, and the front mounts were both ripped out of the glass. In other words the rivets pulled right out of the glass. The nose leg gear fairing was also damaged, but near the top! It looks like the gear flexed way at the top because the gear leg fairning is cracked through just below the intersection fairing below the cowl. It really flexed for this to break this way.
The witnesses said that it looked like the gear leg had a hinge on it and the back of the wheel pant just rolled up towards the bottom of the cowl. They kept going on about how much it moved. I would have argued with them claiming it was impossable from the perspective inside the airplane during the event. But here is the damage backing up their claims.

The front wheel was pulled to get the broken fairings off and there were no signs of damage to the gear. I guess this is what they mean by spring steel. It will flex and return hopefully. The jury is still out on whether it is still serviceable and I'll be calling the factory on Monday. To try and put some perspective to the size of the hole I hit I put a Airport Directory in the hole and took a picture. As you can see the hole is about 1 1/2" deep and about 10" or so around. It was a tie down and the only one on the line that wasn't flush with the ground.
nosewheel69zd.jpg


Here's a shot of the path taken to get to the tie down. If you look close you can see the tire tracks in the dead grass.
nosewheel26da.jpg


Here's a shot of the airplane after taking the broken pieces off. Note how the ground looks. This certainly doesn't look unfriendly to RV's.
nosewheel5en.jpg


Lastly, here is a shot of the wheel pant.
nosewheel81bq.jpg


Regards,

Bryan 9A "Flyin The Flag"
 
Bryan Wood said:
Well, here I sit humbled and deeply embarrassed. ... This is not supposition, speculation, or anything other than just sickening to me.
Click to expand...

Wow Brian - Bummer. _Incredibly_ thorough write up though. Hopefully this will help Van's shed some light on the problem. I'm also interested in what they say about the possible need to replace your nosegear following such a large deflection. It sounds to me like you did everything right.

It sounds like you were able to fly the plane out. If you need any help fixing it up, I'm happy to fly down from Hayward.

Kevin
RV-7A, 50ish hours
 
Excellent report

Bryan, I'd suggest if you had've been travelling a couple of knots faster the nose gear would have collapsed and you'd have had a prop strike, wing strike and other possible nasty damage (much like the RV on the way home from Oshkosh that had the taxi collapse incident reportedly at 4-5 knots). Of course most of these types of failures will never make the NTSB reports. And pride probably prevents most owners from publically reporting their mishaps in a public email forum.

So under the circumstances you are to be commended for making such an excellent and enlightening report. I think other RV builders and flyers will now be starting to realise that the free castoring nose gear principle together with a small wheel and minimal ground clearance from the fairing is a combination that offers a very slender safety margin.

I see that you have the older style of nose gear. I'd be interested to know whether you consider that the newer design with the angled fork would have made any difference in these circumstanes.
 
Bryan-- really sorry to see that and hear that.

I took my old (new) 7a nosegear leg to Harmon and he loped off an inch and retreaded. Then I was able to use the new fork. I'm not flying yet.

I had a guy stop by the RV shop to visit today and he had a hard landing in his 6A and he bent the gear but no strike and Harmon straightened it.

have an old style fork avail.

FWIW
 
plowing effect?

I have noticed that I can't get a normal wooden chock like most FBOs use to fit under my fairings as the bottom of the fairing is too close to the pavement or ground. If Bryans wheel went exactly into the middle of the hole pictured, I wonder if he was then no longer on his wheel, but maybe just resting on the fairing. Then when he gave a little power to get through the hole he was actually pushing or plowing with the fairing as his wheel would have been slightly above the ground and not doing him any good. Sort of like when you bottom out your car when you get stuck with your wheels just spinning. That might explain the fairing failure. I don't know how else to analyse this but having the same plane and the same fairing and nose gear, it does make you think twice about any small irregularity in the earth or pavement. Bryan, I know this must have been a terrible feeling after having built such a beautiful airplane. When people at work ask me what my plane looks like, I often show them a picture of yours. (mine is not painted). I hope everything turns out OK for you and that we (and Vans) learn something from it. Jack
 
Sorry to hear of your mishap, Bryan. Glad the damage was limited.

No doubt, the wheel and ground clearances on our RV's wheel pants are minimal, making it especially important to be dilligent in protecting them (and ourselves). Close tolerances, close ground clearances, a springier than normal nose gear leg, low tire pressure, poor ground conditions, and poor pilot technique have probably all contributed to gear related accidents. Any one, or a combination, can result in bad things happening.

Early in my flying of my RV-7A, I had an incident where my nose wheel pant was grabbed by the tire, resulting in severe deflection of the gear leg and tearing out a small section of the wheel pant. Low tire pressure and too close clearances of the pant to wheel were the culprits. Had I not kept the nose up, as I do, I may have been one of those flip overs. Luckily, I was slow when the nose wheel contacted, and the damage was minimal.

Maybe a sturdier gear with larger tires would be helpful for those who want it. I would prefer to leave my plane as is. I fly from a 1700 ft turf strip that has it's share of whoop-di-doos in it, and do not find the gear a problem. I am an 800 hr pilot with a tail dragger endorsement (100 hrs TD time, recent). There is no doubt sturdier landing gear on many planes. There is also a lot of planes with less sturdy nose gear (Long Easy). I doubt whether most Long Easy pilots would change their gear.

I guess the bottom line is, we have to be somewhat more careful than planes set up for more rugged conditions. Van's does not advertise our planes as "bush aircraft".

I've attached some shots of my wheel pants, showing the close clearances I have on mine. I have been successfull, thus far, with this setup. God forbid, if I should ever nose over, I will most likely find the cause in my mirror.

Roberta

pant24ly.jpg



pant12rx.jpg
 
What a thread!

I see a lot of information here and opinions on both sides of the issue. I see a lot of agreement overall on key issues within this thread.

1. Transition training is a MUST from the best RV CFI pilots available. I did my training with Mike Seager at Scappoose, Oregon.

2. Rolling on the mains as long as possible is the best way to do both takeoffs and landings. Mike drove that point home in my two days of flying with him at Scappoose. The dynamic braking of wind resistance with the nose high saves some wear on the brake pads.

3. Tail dragging a nose wheel airplane. I have done it both ways, in motion and not in motion. The first time was in a 172 as a student pilot on landing where the tie down ring touched before the main gear when I over-rotated in ground effect just above stall speed. The SECOND time was in the RV-6A during transition training with Mike at Scappoose for the same reason. I have NOT dragged the tie-down ring on my RV-9A during a landing. It hit the ground one day when my passenger and I both put weight on the steps at the same time during boarding. Thankfully, one of the tests I made during final assembly was to be sure the tie-down ring hit the hangar floor before the bottom rudder cap.

4. As for landing on grass fields, I have a passive lift reserve indicator on my panel that has RED, WHITE, and GREEN zones on the gauge. During phase one testing, I made only one adjustment to the external probe unde the right wing to calibrate it to match stall conditions. After that, it always shows the indicator needle at the RED/WHITE arc intersection when a full-flaps stall occurs in flight. During takeoff, the airplane always lifts the main gear off the runway with flaps up at the WHITE/GREEN intersection on the LRI gauge.

5. Get the speeds right on approach! I also compare my LRI indications with the approach speed. When the airplane gets "mushy" you want to be in ground effect ready to touch down.

6. Holding the nose wheel off the runway is always easier when you have a passenger and baggage due to the CG being further aft than when you fly solo.

I now have 124.6 hours on my RV-9A and the total flight time in pilot log book is over 310 hours. My RV life is out there for all to see on my web site at www.n2prise.org and many here have seen it and written me about various construction issues during their own projects.

The enjoyment of the building process and the rewards at the completion of that work are why we are all here in this forum. My personal experience from LOE5 is just one more reward that I will long remember, especially with that trophy sitting in my living room book case.

Like the man said, read, ask, learn - - then build what your heart desires. I chose the RV-9A for my own reasons. My hangar mate is building the RV-8 quick-build because he wants to fly and likes the way it looks. He has a Cessna 182 (for sale) and an Aeronca Champ (keeping his rag-wing tail dragger). I want to be sure the quality of his RV-8 is better than my RV-9A since I am warning him of my past building mistakes during the assembly process. The most I have contributed to his project other than the use of my construction tools, was removing all the rivets from his LEFT elevator skin since he wanted to build it again better with a new skin.

And with any luck, I may have a new job in the next few weeks. The timing of my layoff from my last job allowed me to finish my airplane and fly it during the summer.

This is one fun place to hang out on the web. Thanks, Doug and Rosie!

Jerry K. Thorne
East Ridge, TN
RV-9A N2PZ
www.n2prise.org
 
OK, pardon my terrible drawing, but maybe one of you mechanical engineers out there can help.

I propose that a simple retrofit modification to the nosegear could be a skid plate attached to the fork bottom and/or sides. This skidplate would protect the axle nut from digging in (on either the old or new forks).

The reaction force of the skid plate would be opposite of digging in... it would force the nose gear up.

Properly designed, the skid plate could be shaped so that the nose cone fairing could be cut out around it, yet still streamlined.

Van's new nose fork is a step in the right direction, but it is still possible to dig in... the skid plate (properly designed) might totally eliminate this tendency.

If anyone from Van's is monitoring this list, I think it would be easy to set up a test jig to determine the best configuration. If it works, it's a lot cheaper than a whole new gear leg design.

Vern Little
RV-9A

nose_gear.jpg
 
Vern: good idea

I'm no engineer but it sounds and looks like a good idea. It seems like it would help take out that hard point that digs in on some cases. Send it to Van's for comments and mention this thread that has been keeping our attention for quite awhile. Jack
 
Vern:

If Van's doesn't want to do it, perhaps one of the aftermarket parts manufacturers would.

I am wondering if there is some way to just bolt this "skid" to the nose fork and not involve the nut holding the fork to the gearleg. Van's (or whomever) may not want to mess with the breakout force requirement with the current design. You could even install it without cutting out the forward bottom area of the wheel pant with the understanding that this is a safety device that will sacrifice the wheelpant yet keep the airplane from noseing over. As the skid makes contact with the ground, the wheelpant would just crush around it.

I echo that this is a very good idea. I sort of had the same thought. It would involve minimal design/manufacturing effort, Cause little weight gain, as well as no noticable loss of aesthetics.

It just makes sense, IMHO


Regards,
 
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Skidplate

I agree that it could fit under the nose cone without modification, and attach to the sides only by drilling and tapping the fork. It might even be easier than that... I have some ideas.

I'll investigate the feasibility a bit more when I'm at the airport tomorrow.

Stay tuned.

Vern
 
Houston, we have a problem

Egads, it's an epidemic
-Vern
================


Vans RV-9A, G-CCZT
Report name:
Vans RV-9A, G-CCZT
Registration:
G-CCZT
Type:
Vans RV-9A
Location:
Bicester Airfield, Oxfordshire
Occurrence date:
14 April 2005
Category:
General Aviation - Fixed Wing
Summary:
The aircraft was landing on Runway 13, the grass surface of which was damp, in a two to three knot easterly wind. The pilot reported that, while rolling out after a ?very acceptable landing?, he applied a small amount of back pressure to the control column to keep the weight off the nose wheel. As the speed decreased through about 30 kt the aircraft encountered some surface undulations and the first of these pitched the aircraft into the face of the second. The pilot stated that the ground in that area was soft and it appeared that the nut at the bottom of the nose landing gear, in front of the wheel, had dug in to the surface causing the nose leg to bend. The pilot considered that the accident was partly due to his landing technique, in that he did not apply sufficient back pressure to ensure that weight was kept off the nose landing gear as long as possible. He commented that he was very new to the aircraft and needed further practice on this aspect of his flying. He also concluded that he should have ensured that the landing surface was acceptable. He stated that the airfield is known for being a little bumpy in places and that, being a new operator there, he was not familiar with the areas to avoid. The grass runways at this airfield are unlicensed and, in practice, identify the landing direction only. The runway lengths are defined but there are no runway edge markings and the pilot stated that all the grass is mown to a uniform length. The airfield is primarily used as a gliding site. Light aircraft are welcomed but pilots are advised that it is at there own risk. General Aviation Safety Sense Leaflet 12C, entitled Strip Sense, provides advice on unlicensed aerodromes and private strips. It includes a section on ?Assessing the Strip? and the factors to consider. The pilot stated that in this accident he encountered the undulations half way along and towards the left of the landing area.

http://www.aaib.dft.gov.uk/publications/bulletins/august_2005/vans_rv_9a__g_cczt.cfm
 
Update from Van's

I contacted Van's on the nose gear issue, and bounced the skid plate idea of of them (pardon the pun).

They are standing fast that the problems that are being experienced are pilot-induced. They have no plans to investigate further because they are busy with the RV-12.

Technically, they are correct... if you left your airplane in the hangar and did not fly it you would not have had the accident. Let's face it-- the landing gear on RV's is much smaller than a typical certified aircraft, and even mole hills become mountains, relatively speaking.

Personally, I believe that an operating limitation placard should be placed in every RV-A aircraft: "Land, take-off and taxi on smooth surfaces only".

This is not a joke. I have decided to change airports from a turf field to a paved field, and this was one of the considerations.

Vern Little
 
osxuser said:
Tailwheels rock.
Click to expand...

But..........retracts are slicker...

And highwing taildraggers with NO wheelpants, DO make for excellent back country bush planes! Check out the Aviat Husky; I'd love to have one.

IMO, as a long time motorcycle rider (40 years), this debate is like Harley versus a Wing. While the Harley is excellent for canyon riding, cross city and bar hopping, as well as a sound that rivals the P-51 Mustang (IMO, the best looking aircraft....ever); it's not the best long haul cross country machine, where a Honda Wing or BMW will be more practical. Everything has a purpose, and get both, or three, or whatever.

edit: Personally, I'm tired of this rough ground debate & RV's. Anytime wheel pants are involved for increased airspeed, you're taking more of a risk in a rough, or semi rough fields, where "catching" pants can effectively stop the wheel rotation. Has anyone paid attention to the fact, that the newer two piece wheel pants, that increase airspeed, due to lower drag, have less wheel clearance than the older one piece versions?

Do you want increased airspeed, or bush plane abilities?
Or just try to argue that somehow an RV is a backcountry bush plane...

A local aircraft builder has created a highwing taildragger out of RV4 parts. Perhaps, this is the best solution, without the wheelpants, of course!
 
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The one thing I think I've gleaned from this thread is that wheel pants, small wheels, and turf, don't mix. That is, aircraft designed to operate off of turf don't have wheel pants or tiny wheels. Note also that bush planes don't usually include nose wheel aircraft either.

On this link of some notable bush planes, I note that NONE of the ones with wheels have wheel pants, and the rest are either floats or ski's.
Take a look at the "nose over" photo of the Fokker Universal and wonder if online newsgroups have discussed that kind of scenario to death.
http://1000aircraftphotos.com/NorthernCanada/BushPlanes.htm

The RV design does LOT's of things well, including landing on turf for the most part. But it looks to me that if a person INTENDS to build his RV for frequent soft field landings, he/she should at least leave the wheel pants off permanently and take the subsequent hit on cruise speeds, and yes, build a taildragger rather than a nose wheel aircraft. It might even be practical to fit the next larger size tires on it as well.
Then it's off to Canada you go. ;)

My 7A is being built as a high speed cross country machine and I don't care if I never land in grass since most "real" airports are hard surface at the places that I want to travel to. At the same time, I'm not going to be concerned if I do want to make a fly-in or two on a grass runway as long as I'm totally confident in my soft field landing technique and my AOA is working properly.

Hopefully, this discussion will lead to saving a lot of people some grief if it gives them some sober ideas about how rough field landings should be made and that the RV, even the taildraggers, are NOT bush planes.
 
Vern,
I think you missed the fact that most of the WWII fighters AND bombers were brush/ soft field planes, and they were mostly taildraggers with high and low wings. It seems to me that that application requires heavy duty landing gear that are best made retractable, without the need for wheel pants.

As far as RV's go, it might be worth a look at easily removable wheel pants and a larger front wheel that could be used, when called for, and replaced when not needed?

FWIW, Im seriously considering looking into building a lightweight, but strong, carbon fiber reinforced front strut for my 9a to provide strength and stiffness to the flimsy EOM design. (I have a lot of good friends that design/build composites for NASA and the USAF). Does anyone know how much max weight is supported by the front wheel?
 
max weight on the nosewheel

Does anyone know how much max weight is supported by the front wheel?
Click to expand...
Depends on how good your landings are!

My guess would be that they need to meet the FAR 23 Drop Test Specifications, and that's about it.

How about a design like this:

 
Last edited:
a picture is worth 1000 words

vanlle2000 said:
I've had the chance to fly both a 9A and a tailwheel 9. About 200 hours in the trike, 60 in the t/w. I prefer the trike. Easy as pie to land, view forward while taxiing is great. T/w is a bit more work, and not as easy as a 6 to land, even though it will fly quite a bit slower. On a windy day, it will keep your attention. Nothing nasty, but definitely more work. Can't find a difference in the air, so I'll take the one that makes taxiing and landing less work.

As far as the nose gear, it seems the really high time A pilots are doing all right...Paul Rosales and Mike stewart must have thousands of landings between them. The factory trikes including the ramp rat Van calls Ole Blue are going fine with no instance of nose gear failure. One of the factory pilots told me stories of the ugly things that have been done to that airplane over the years, and yet is survives to be (I'd guess) the highest time RV in the world. If any gear problem were to surface, wouldn't these airplanes would have found it first?
Click to expand...
Yes, the really high time A pilots are doing well. So is the factory trainer. With PROPER TRAINING, even low time pilots like me can land in places like these:
Coldfoot, Alaska
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Big Creek, Idaho
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Moose Creek, Idaho
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Proper training, proper technique, and GOOD JUDGMENT go a long way.

Also, since each and every RV builder is the manufacturer of his/her aircraft, it is that builder's perogative to install as big of a nosewheel as they want. If you put a really huge ugly nosewheel on your RV, please park next to me at a fly-in because it will deflect attention away from my poor paint job.
See ya!
 
Mickey,
I like your idea, but the spring needs some dampening- as it is, the front end will bounce (oscillate) down the runway. The geometry is better than the 90 degree "plow" that Vans used for uneven surfaces, maybe less stable against wobbling.

Something along the lines of a motorcycle fork arrangement (telescoping sprung shock absorber) might be better.
 
When did Van's change the nosegear fork to get more clearance? I got my finish kit in April and by looking a various peoples pictures I would say mine has some angle to it where others (old ones?) are almost level across the bottom? Just curious if mine is a new or old one.

Thanks,
Scott
#90598 Baffles/Details
N598SD reserved
 
Scott, if yours is angled slightly downward to the rear, then you have the new one that gives about one more inch of ground clearance up to the nut.
 
rv8ch said:
Depends on how good your landings are!

My guess would be that they need to meet the FAR 23 Drop Test Specifications, and that's about it.

How about a design like this:

Click to expand...

In the end, the loads on the tube are the same (it has to react the forces on the spring). The trailing link (if it exteded down as much as possible) would help to keep the tube itself from digging in, but it also adds a lot of weight (you need a shock absorber with that spring).

Upward loading (vertical through the nosewheel) doesn't seem to be an issue. The loads that seem to be causing the problem are when the tube is bent down/back (nosewheel gets caught in a pothole) and possibly to the side at the same time. Then that long tube becomes a pretzel.

The correct structural solution is to bring the attach point forward, so the tube is shorter (keeping the nosewheel in the same location). If that pesky engine weren't in the way it would be easy to do :rolleyes:

Dennis Glaeser
7A Wings (main structures done, working on ailerons and flaps)
 
DGlaeser said:
... but it also adds a lot of weight (you need a shock absorber with that spring)...
Click to expand...
Not to bring up the obvious, but why would Mickey's design suggestion NEED a shock absorber when there is no shock absorber on the design as it now stands?

-mike
 
mlw450802 said:
Not to bring up the obvious, but why would Mickey's design suggestion NEED a shock absorber when there is no shock absorber on the design as it now stands?

-mike
Click to expand...

Because with the spring there the nose would bounce up and down and make your passengers sea sick on landing. Sort of like when your shocks on your car are worn out.
 
My point was that there is no damper on the current nose gear design so why worry about needing one on a different design?

-mike
 
mlw450802 said:
Not to bring up the obvious, but why would Mickey's design suggestion NEED a shock absorber when there is no shock absorber on the design as it now stands?

-mike
Click to expand...

If the trailing liink (TL) spring were the same or stiffer than the gear leg, it would act as if ithe TL were solid - the leg would act as if it weren't there (no benefit obvously). A softer TL spring would initially take the load and an absorber would benefit the leg by releasing the absorbed energy slower than the initial input. Without the absorber, the leg sees the same load at the same rate, just a bit later as the spring rebounds (no real benefit from a load standpoint). Since the load we're concerned about is the 'pothole scenario', the trailing link with absorber could possibly take an initial aft-bump (that would have bent the rod) and pass it on to the rod slower, and hopefully the rod would absorb it better. That's the concept anyway.

Dennis
 
trailing link

the trailing link with absorber could possibly take an initial aft-bump (that would have bent the rod) and
pass it on to the rod slower, and hopefully the rod would absorb it better.
Click to expand...
Totally agree. Visio had the cool spring, so I just threw
that in there. I would design in a dampener as well, for the reasons
Dennis mentioned.

Of course, a system like this could allow for a slightly lighter nose gear leg,
but probably not enough to offset the additional weight of the spring/dampener
and the swingarm.

Also, getting a nice fairing on there would be an additional challenge.

It might be just a lot simpler to put one of those "tundra tires" on there
with a big honkin' wheel fairing and be done with it!

Tundra.tire.jpg
 
IMHO:
After Bryan Wood?s incident in an earlier post it seems clear what is happening in these failures. The fairing catches on the ground, the leg flexes backwards which angles the damper nut area more into the ground. Forward momentum does the rest. The good news is that the strut survived this punishment so I would think that the strut would survive normal use and abuse provided the fairing does not catch the ground and provided the wheel is free to rotate. It seems to me that easiest, non-technical solution would be:
1. Install the new angled fork.
2. Remove the nose fairing when operating on unknown or dubious grass or dirt airstrips.
3. Keep the tire pressure up.
About the only other thing that would really help would be a bigger tire.
Finley
9A (under construction) Australia.
 
IMHO:
After Bryan Wood?s incident in an earlier post it seems clear what is happening in these failures. The fairing catches on the ground, the leg flexes backwards which angles the damper nut area more into the ground. Forward momentum does the rest. The good news is that the strut survived this punishment so I would think that the strut would survive normal use and abuse provided the fairing does not catch the ground and provided the wheel is free to rotate. It seems to me that easiest, non-technical solution would be:
1. Install the new angled fork.
2. Remove the nose fairing when operating on unknown or dubious grass or dirt airstrips.
3. Keep the tire pressure up.
About the only other thing that would really help would be a bigger tire.
Finley
9A (under construction) Australia.
Click to expand...
Finley,
You could also add:
4. Mount nose gear fairing an inch or two higher.

Best,
 
Moose,
Good suggestion. I am not up to this stage in construction so I don't know if it is possible to mount the fairing higher. I would guess that the limiting factor would be the damper nut. Maybe the new, more angled fork would allow the fairing to be mounted higher. Is there any out there who has done this??
Finley
 
Finley Atherton said:
Moose,
Good suggestion. I am not up to this stage in construction so I don't know if it is possible to mount the fairing higher. I would guess that the limiting factor would be the damper nut. Maybe the new, more angled fork would allow the fairing to be mounted higher. Is there any out there who has done this??
Finley
Click to expand...

I have the finish kit with the new angled forks on the way. I had already decided to raise the bottom of the fairing to gain increased clearance. Two inches is clearly insufficient for confident movement on anything much worse than a bowling green. I may have to modify the existing fairing extensively ...but whatever it takes.

In reality now that Vans have provided the angled forks you can see that it doesn't make sense for them not to change the fairing design (or at least provide an option for those intending to use grass strips). Tell me what is the point of raising the fork when the fairing will bottom out at the same height.

Vans redesigned the nose gear on the RV10A, no doubt at least partly in response to concerns about the performance of the gear on earlier models. Not many people know the extent of the changes because there aren't many 10s out there...and most 10 builders probably haven't got the finish kit yet. The 10 gear is considerably more sophisticated. From the outset it incorporated the angled forks, a hinge action at the top of the gear rod and shock absorbers.

They're a strange mob at Vans. They keep rolling on to new models and seem to lose interest in tidying up the old ones (the same goes for their plans and instructions!!!)

There could be some good business coming up for a third party supplier with a more conservative nose fairing for the new angled forks.
 
Nose skid

After investigating the fabrication of a nose skid, I determined that I don't want to fabricate a metal skid plate.

One of the causes of nose gear dig-ins is the collapse of the wheel pant nose cone. This may be starting the chain reaction of wheel binding-fork bending-axle nut plowing.

Instead, I'm considering a fiberglass skid plate that will minimize the collapse of the wheel fairing as well as protect the axle nut.

It's cheap & easy... and probably good insurance.

Comments welcome. The drawing is a bit crude, so you need to imagine the complete nose fairing. Space between the nose fairing and the axle fork/axle nut assembly will be filled with fiberglass flox. I chose flox because it has some elasticity to it... hopefully absorbing some energy.

In the event of the nose fairing impacting a pot-hole (for example), the force will be transmitted to the fork assembly directly, minimizing collapse of the fairing. Furthermore, the axle nut is protected by the flox. Resultant forces should be more vertical than lateral, helping to minimize the tuck-under of the fork.

During lay-up, I plan on greasing the fork assembly and axle nut to prevent the flox from adhering. I'll also put a few layers of tape over the castle nut to allow space for it to be turned for adjustments later.

You'll know if it's working if you scrape the bottom of your fairings but don't collapse the nose gear.

Comments?

Vern Little

nose_skid
 
Mount Point.

The only satisfactory fix is to redesign the Engine/Nosewheel mount to move the Nosegear/airframe attach point forward, such that the spring strut is ahead of the nose wheel and slope backwards.
The current design with the strut angled forward means that the further the nosewheel bends back the more it moves DOWNWARDS and the more load it places on the strut, and so it bends still more and more load is placed on the strut,etc. etc. etc.
Which explains why the bending is so large at even low speeds.
If you aren't convinced, go out to your favorite grass strip and trying pushing a stick down the runway angled as per the current design. Then try dragging it behind you with the equivalent angle. If it strikes a rut it will lift and relieve the load.
Pete
 
nose gear

I woke up about two hours before the alarm this morning with this idea. All you engineering types please think about it, and if you think it would work please improve on it and maybe we can help our situations.

Picture this: Running down the front of the nose gear leg is a rope, or a cable, or whatever. It is clamped every 2-3" with a hose clamp or whatever, but this would allow the gear to flex forward as weight on the airplane and landing would impose, but would act as a deterent to the leg bending backwards. It just might prevent these gear from flexing backwards enough to dig in the nut and taking the whole thing over. It would be light, cheap, and something we could all do in an hour or so. Can anybody see why this would not help? I'm no engineer, just somebody who awoke from a sound sleep with this idea. This combined with some sort of skid seems like it would greatly reduce chances of a gear failure. This of course could be optional for those who know how to land and don't believe they are at risk during taxi.

Bryan
 
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