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  #21  
Old 06-17-2020, 03:26 PM
Discus2b Discus2b is offline
 
Join Date: Mar 2016
Location: Willis Gliderport
Posts: 186
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Quote:
Originally Posted by DanH View Post
Ok, good.

In a typical tail-low wheel landing, a bounce is the result of too much vertical velocity and/or too much airspeed.

Way back when, in the Cub days, a mentor convinced me to use a visualization for wheel landings, which was, strangely enough, "Don't land, just fly very low". The plan is to try to fly 3" above the runway. Since the aircraft is slowing, it won't stay there, but if the pilot tries real hard to keep it there, it will fly onto the surface with very little vertical velocity.

Too much airspeed simply means more lift, so the wing magnifies any bounce. I'd suggest no more than 70 across the numbers, slowing.

Someone mentioned stick forward at touchdown to pin the landing. I would strongly recommend against that technique in an RV swinging a 74" prop, because it has a good change of turning it into a 72" prop.

Someone show him the one-wheel trick. Kills bounce energy in any taildragger. If after initial touchdown it skips back into the air, immediately drop one wing just a little. The next ground contact will be on the low wheel. The vertical energy will then dissipate in rolling the airplane toward the high wheel. Try it.

Wanna see one? Go here, start at 7:00, and watch Dan bounce. Moderately gusty day at OSH. I want to hit the yellow dot, run a little long, and let it sink in a vain attempt to save my pride, resulting in a bit too much vertical. I get a skip, so...drop the left wing, and shazamm, no further bounce. No stick push either. No pitch chasing of any kind. I like my prop.
https://youtu.be/ixcYBkXbAAw
There is no way you will hit a 74? prop tip ?pinning? a wheel landing in the 14. And 9/10 wheel landings will require a slight forward nudge to keep the aircraft on ground...why? you ask...is because wheel landings are ?flown on? vs. ?flared on?.
Myself....always wheel landings on hard surface, flare landings on grass.
As far as bouncy....yes indeed...the 14 is the bounciest of the 28+ draggers I?ve flown. And it always happens when a flown/flair combo landing is attempted. And this is due to a lack of confidence in doing wheel landings or sight picture. The fear of striking a prop or tipping over due to the excellent visibility.
My trick....with this bird...ever so slight ?forward? trim after full configuration and ..zero flaps (go around, my choice) if runway length is not an issue. With main gear touchdown I relax the wrist a little allowing ever so slight down pitch to ?lock on? as the aircraft slows below flying speed. Then one more gear (tail) to softly land and voila.
A go around is always the first option, never the last and a big part of safe conventional aircraft operation.
I can only imagine the slight forward trim spooling up all the brains but,
36,000 + hours and no runs, drips, or errors ... so far..
R

Note: 74? vs. 72? Covered in previous threads, a possible 14 issue with HARD LANDINGS.
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  #22  
Old 06-17-2020, 04:01 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by Discus2b View Post
There is no way you will hit a 74” prop tip ‘pinning’ a wheel landing in the 14.
Certainly not when pinning a clean roll-on. Here, think about the thread title, i.e. "The Rabbit"...rusty pilot, multiple hops.

The 14 has long legs, so I cheerfully admit it would require serious foolishness, but you know what they say about "foolproof". I submit this example, a nice -14 in the hands of a new owner.

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Last edited by DanH : 06-17-2020 at 04:13 PM.
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  #23  
Old 06-17-2020, 05:35 PM
jdmrv7a jdmrv7a is offline
 
Join Date: Jan 2018
Location: DFW
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I recommend you look at Van's plan Section 40B (Tailwheel) landing gear drawings and inspect for cracks in the engine mount around the landing gear. If you can jack the plane off the landing gear you can determine if there is any play in the gear or Gear Axle Fitting U01421 L&R or axles.

On the 14-A, a missing U01402 bracket under the floor pan will certainly make the landing gear bounce. Lifting the plane to inspect the stability of the gear is a good starting point. After 175 hours I changed to Michelin tires, that was a big improvement in landing and handling. Mains 40 psi, nose 35.

And yes, Mike Segar is a very effective RV instructor with over 20,000 RV hours. He laughed at my heavy aircraft skills the first hour of my transition training. He's the best.
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  #24  
Old 06-17-2020, 08:34 PM
LR60 LR60 is offline
 
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Default What length prop

Dan,

Was that a 74? that got scrubbed?
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  #25  
Old 06-17-2020, 09:36 PM
Taltruda Taltruda is offline
 
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How high do you have to get the tail up to hit the prop! That?s crazy!
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  #26  
Old 06-17-2020, 10:32 PM
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Mike S Mike S is offline
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Quote:
Originally Posted by Taltruda View Post
How high do you have to get the tail up to hit the prop! That’s crazy!
Depends on how much you compress the gear in a hard landing.
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Last edited by Mike S : 06-18-2020 at 12:33 AM.
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  #27  
Old 06-17-2020, 11:28 PM
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Av8rRob Av8rRob is offline
 
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I have a 74? prop on my -14. In level attitude I measured 13? from tip to ground. That would be one hard landing/ bounce.
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  #28  
Old 06-18-2020, 07:30 AM
mountainride mountainride is offline
 
Join Date: Jan 2018
Location: Golden, Colorado
Posts: 58
Default RV-14 landing

I have 85 hours on the -14 with a 74" prop. After my transition training and coming in on short final at 75 KIAS I now slow to 65KIAS on short final.

It is a difficult airplane to get greasers out of. Its not twitchy or wild feeling but it can feel a little bit stiff legged when trying to get a seamless air to ground transition. I would say I get a true greaser maybe 1/3 of my landings and it requires a steady hand, it won't do it if muscled on. You can muscle it on and have a near perfect speed and descent rate but it may skip or "bounce" an inch of two before settling on the mains.

Its definitely not like flying a large aircraft with huge shocks that absorb the worst landings or a 172 that you can consistently grease on.

Maybe this will change as I get a few hundred more hours in the -14 but I would say that landings like that were pretty normal. I also had the same experience with Seager in the factory -14. Its greases on easy in grass!
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  #29  
Old 06-18-2020, 08:30 AM
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DanH DanH is offline
 
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I imagine an RV-14 prop is pretty safe at first ground contact. As Rob said, a fella would have to hit hard, given a more-or-less level attitude. That's not to say there is a lot of margin. If you're really curious, Vans has done drop tests, and Neal Willford published a good landing gear spreadsheet via EAA.

Example from a past design project. It's an RV-7 sized leg at 3.7G, 36 tire psi, no braking, and 1850 lbs, on a biplane frame. Total loss of ground clearance is the sum of leg and tire deflection. Clearance can get used up pretty fast.



Lawn chair observation says the spit hits the fan during the subsequent hops, if the pilot chases them in pitch...the rabbit hop I think Bill was describing. We've all seen serious PIO at one time or another. If you can tear the nose leg off a tricycle, you can surely drive a prop into the ground with conventional gear.
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Last edited by DanH : 06-18-2020 at 12:44 PM.
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  #30  
Old 06-18-2020, 01:08 PM
Discus2b Discus2b is offline
 
Join Date: Mar 2016
Location: Willis Gliderport
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Quote:
Originally Posted by DanH View Post
Certainly not when pinning a clean roll-on. Here, think about the thread title, i.e. "The Rabbit"...rusty pilot, multiple hops.

The 14 has long legs, so I cheerfully admit it would require serious foolishness, but you know what they say about "foolproof". I submit this example, a nice -14 in the hands of a new owner.

Wow!
Hence my comment about ?Go Arounds?. I go by the one try rule, always have. Not good on the first, go around. No hopping, no saves, no retries, nadda, zip...go around. It?s part of the business. Do it until you run out of gas, then it gets real easy.
That prop looks like a over rotation on takeoff. Hmmm.
Ouch...
R
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