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02-06-2013, 12:28 PM
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Join Date: Dec 2007
Location: Fredericksburg, TX
Posts: 662
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Reading this thread got me to thinking (always a bad thing!). I originally set my toe with the aircraft in the tail-up nattitude; my goal to get it to zero. Touchdown handling has always been very good; rollout requires a lot of attention. I decided to re-check toe today using Dunlop optical equipment left over from my car racing days. With half fuel and pilot only I got 30' toe-out with the tail up and 35' toe-in with the tail down. As you can see that's over 1 degree of toe change with changing attitude.
I'm tempted to put a little more toe-out to make tail-down handling less challenging. Thoughts?
__________________
Jim Averett
RV-8
TS36 - Silver Wings
Fredericksburg, TX
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02-12-2013, 02:02 PM
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Join Date: Feb 2013
Location: Litchfield Park, AZ
Posts: 13
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3 point landings, T-18 and RV4
Quote:
Originally Posted by SHIPCHIEF
I am building an RV-8, but I currently fly a Thorp T-18, which behaves very much like the descriptions I've read here.
The learning curve is steep, and the amount of time available during each landing is brief.
You only get a few seconds per landing to try something new. Also, if your experiment was a poor choice, things can get exciting for a moment, and you might not remember what it was you were trying to change.
My T-18 has short stiff gear. A 3 point landing on a bumpy runway, or a wavy one will re-launch the plane, because, as one poster pointed out, the plane is still @ flying speed. All it needed was an increase in the angle of attack, sufficient to lift it's weight. Then you climb a ways and run out of energy, fall, and begin bouncing. If you re-arrive on the main gear, you porpoise down the runway. If you touch the tailwheel first, you hobby horse down the runway until the tailwheel bounce frequency overcomes the maingear bounce frequency, whereupon you begin to porpoise. Hopefull the speed has been slowing enough to firmly attach the plane to the ground. Now steering and brakes become more effective, then dominant.
For me, the cure has been a 3 point arrival, with a healthy push on the stick to raise the tail when the tailwheel bounces. Now the angle of attack is held down and the plane is not propelled skyward, although the stiff gear may bounce a few times.
That is easier than a wheels landing, because wheels landings are frequently miss-timed. The main gear touch, the tail droops a bit from inertia, so the angle of attack increases and the plane re-levitates. If you 3 point it on, the airspeed is as low as you can get. Then lift the tail to hold the plane on the ground. Hold the tail up until speed has reduced to less than flying speed, then it will lower it'self eventually, even if you have been pushing the stick farther forward to hold the tail up as the plane slows.
This is my experience, which I share, but I'm not an instructor, so don't try this without the appropriate help etc...
Oh, and my RV-8 is sooo close. I'm wiring the panel and adding the placards & labels. Soon, Soon. 
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I have flown both the RV4 and T-18. Both had O-360 with c/s props. In my opinion they land very differently. I would wheel land the RV with the tail low and still would occasionally bounce. The T-18 on the other hand had a very small tail and has a tendency to pitch down in slow turns such as base to final turns... I would land tail wheel first and with the very stiff gear on the Thorp it would just stick. I never had an issue of bouncing.
I think alot of it has to do with airspeed control......
My two cents worth...
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02-12-2013, 02:35 PM
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Join Date: May 2008
Location: Pottstown PA
Posts: 209
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On the original post. Sounds like a geometry issue, which others have answered. So I am going to comment on some of the other non-geometry comments.
I do not mean this to be critical to those who choose to wheel land regularly. But I want inexperienced pilots who are thinking about buying an RV-8 to understand this wheel landing versus full stall landing is much ado about nothing. When properly trained, you should be able to full stall or nearly full stall land a tail dragger ALL THE TIME unless the winds are high. Wheel landings are a technique used to overcome higher cross winds, or in the case of aircraft with lousy forward visibility (long noses like the P-51, Spitfire, etc), a way to SEE where you are going. As the RV-8 has outstanding forward visibility even for guys around 5’ 10” or less, wheeling it in is hardly a necessity. Fun, yes! A technique you need to know for those days when the wind is stupid fast, YES. But no easier in my experience, then a performing a standard 3 pointer even in cross winds under 12 or so knots. If nothing else, you will save your tires a lot of abuse - and maybe save your prop. There are real reasons you do NOT want to wheel land all the time. Rough and short fields come immeidately to mind.
I am a bit baffled by this endless tripe about the RV-8 not liking three point landings, while being supposedly "easier" to wheel land. If it was built RIGHT, it will do both with equal aplomb. That may ruffle some feathers but it needs to be understood clearly by any new builder or buyer who is thinking about the RV-8, that when set up properly, the RV-8 can handle either landing type with ease - if anything, the wheel landing takes more effort and better timing/judgement, so you are cheating yourself if you do not master the 3 pointer. And worse, if you do not approach a wheel landing properly, you can destroy your prop. Poor technique or poor equipment location (CG) does not indicate poor design - so if you feel like you HAVE to wheel land an RV-8, something is seriously wrong. Now...why am I pointing this out?
I’ve actually met guys who are AFRAID to 3 point their RV-8 because of all the tripe they’ve read on VAF about the topic. Every time I read about how the bird "prefers" to wheel land I think somewhere, an instructor has not done his job OR, someone is trying to land with trim set to neutral - at a higher than necessary speed. Keep some forward trim. Don't blast across the fence at 80 knots unless the wind demands it, and time the flair in a manner that holds the bird off the ground as long as she will take it. Walla. Three point squeeker in a couple of 100 feet. If the -8 is squirrely on landing you probably came in too hot. When you come in at a proper speed and three point it, she usually rolls out with very little fuss, at a very slow rate of speed. If she still does not perform properly, you probably mounting too much equipment forward or you didn't account for the wind. And to put it into perspective, my own RV has a CS prop, and with a full tank of gas AND a full tank of smoke oil loaded in the forward baggage, flying Solo, she still 3 points easily. Which tells me something is screwy if someone thinks they have to wheel land all the time.
__________________
Scott "Lawbreaker" (yeah, its a fair cop!)
RV-8 N710PX "Bad Attitude!"
Last edited by wera710 : 02-12-2013 at 02:39 PM.
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02-12-2013, 05:55 PM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Scott, I don't think that any really experienced -8 pilots will say that you HAVE to wheel land it all the time - you're overstating the case there, and using absolutes sort of blunts your arguments. Of course you can three-point the -8, but it should be understood that it is NOT a full stall landing at that point. If you full-stall it, you'll have a one-pointer (the tail wheel). A three point is simply a special case of a tail-low wheel landing in which you touch the tail wheel at the same time as the mains. In fact, if you read most experienced pilot's posts or notes, they say that the easiest landing is a "tail low" wheel landing.
If you are landing under special conditions (short, soft), then you use the three-point technique because it is appropriate. I routinely land in less than 1,000' using the tail-low wheelie because it works fine.
So why the caution about three-pointers? It has to do with aft CG's - a heavy passenger, for instance. it has been shown that with the CG well after, the stick force gradient goes negative as you slow down below about 65 knots (+/-). A pilot needs to be ready and aware of this or they can over-flare with a passenger. A short, soft landing with aft CG is the most challenging situation, and new pilots need to know that this can occur - I have seen some damaged fuselages because a person was not ready for it. They would have been ready for it if they had discussed this with an experienced -8 pilot.
Use what works best for you, test it in Phase 1. It is definitely NOT a sign of bad instruction or bad transition training if a pilot chooses to use the tail-low wheelie - it is a choice that works well. I agree with you that it is bad if a pilot is scared of any condition in which the airplane can be flown - this IS a sign of incomplete transition training, and should be addressed.
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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02-12-2013, 06:49 PM
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Join Date: Mar 2007
Location: Sonoma County
Posts: 3,821
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I doubt if you will ever see 4 pages dedicated to landing a trike.
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VAF #897 Warren Moretti
2019 =VAF= Dues PAID
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02-12-2013, 07:22 PM
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fugio ergo sum
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Join Date: Apr 2006
Location: Carlsbad, NM
Posts: 1,912
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Quote:
Originally Posted by gasman
I doubt if you will ever see 4 pages dedicated to landing a trike.
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Oh so true! The tailwheel airplane is interesting and worthy of discussion.
__________________
Larry Pardue
Carlsbad, NM
RV-6 N441LP Flying
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02-12-2013, 07:32 PM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Quote:
Originally Posted by n5lp
Oh so true! The tailwheel airplane is interesting and worthy of discussion.
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AMEN.
I like it and am tuned in, lots of good stuff here.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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02-12-2013, 09:37 PM
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Join Date: Feb 2009
Location: Naples, Fl
Posts: 82
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three point aft cg
paul
what do you mean by stick force gradiant goes negative?
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02-13-2013, 12:27 AM
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Join Date: Jan 2005
Posts: 52
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Well for what it is worth. My 2 cents worth is you should be able to do all the landings very proficiently that the airplane is capable of. I like to do three point full stall landings and wheel landings. If my three pointers are not full stall at touchdown they are very shortly afterwards because the stick is buried all the way to the rear. I find the RV-8 does three points landings just as well as wheel landings. I also find that the RV-8 is a little more sensitive on directional control than for example the RV 4, 6,7. Having given more than 15000 hours of dual in tailwheel airplanes I would never consider starting someone out with wheel landings in a new tailwheel airplane. Most pilots are not going to be ready to start wheel landing an RV of any kind until they can three point it well. Wheel landings can provide a very smooth touchdown if you are experienced, they are not very forgiving if you botch it. Consider this, one of the ways to recover from a botched wheel landing is to convert it to a three point. If you have a tailwheel RV loaded out of CG to the rear you get pitch reversal which means you will be pushing forward to keep from over rotating or flairing too high while you are touching down. Mike
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02-13-2013, 06:48 AM
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Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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Quote:
Originally Posted by gasman
I doubt if you will ever see 4 pages dedicated to landing a trike.
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A search for "A model + flip" may change your mind.
There's more than a few words discussing landing technique in this 35 page monster:
http://www.vansairforce.com/communit...ght=model+flip
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.
Michael Robinson
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Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
Last edited by Toobuilder : 02-13-2013 at 07:03 AM.
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