wafer
Well-Known Member
- Joined
- May 12, 2006
- Messages
- 155
For those of you considering a tri-gear Sonerai, I noticed there is not too much written about construction and what to expect flying. I am certainly not a tri-gear expert, but offer the following observations as an LTS builder whose been flying for ~ 80 hours.
Tail dragger vs. Nose wheel Configuration
First, please do not consider the tri-gear only because you do not have tailwheel experience. In order to get some stick time, and I do suggest you should obtain stick time before flying a Sonerai, chances are you will fly a taildragger. You will probably find that flying a taildragger is not extremely difficult. It is more technique to learn, and more tasks to get proficient, but certainly obtainable with time and practice. Besides sport plane aesthetics (tail draggers do look better), to me the biggest advantage of the tail steering design is less drag. Also, tail steering is needed if you plan to do grass strip landing. I am not trying to talk you out of the nose wheel configuration (I love it), just do not discount the tail steering configuration because you have zero tail time.
The most positive attribute the tri-gear configuration provides a real nice view while ground maneuvering. And upon landing, you get to enjoy that nice view right after touchdown. To me, it is the biggest plus for the nose steering design regardless if it is a Sonerai or not. Some call it a safer configuration; others view it as the modern day standard arrangement. Insurance companies consider it less risk, and factor that in the premium. For me, I am just more comfortable with the nose configuration.
Though some may argue looks, the biggest drawbacks of the nose wheel design is the amount of drag produced, and to a degree weight. So let’s just say less performance. How much? The only way to really make that comparison is with the same aircraft flown in the two configurations. In a March 1983 Sport Aviation article on the tri-gear design, Monnett Experimental Aircraft’s performance testing yielded 2-3 mph lower at top level speed at 75% cruise. To date, my experience with top speed has been below expectations. Not a disappointment, just not as fast as others obtain. As my plane is a heavy at 650 lbs. empty, and I am another 210 lbs., I am sure there are other factors other than the nose wheel configuration that yield my 125 mph CAS at 24 inches manifold pressure performance. Maybe I have some more speed tweaks I have yet to discover, but that is my experience to date. If squeaking the most performance out of your bird is your main goal, maybe the tri-gear is not for you. Is the tri-gear a “dog?†Maybe in comparison to a light, powerful Sonerai 1, but otherwise hardly not. My plane takes my breath away every flight. Just consider you will lose some performance.
The other drawback is soft field operations, as soft field is not recommended. I do not know the details why, just that it is not recommended. This maybe a show stopper if soft field ops are your normal intentions.
Taxing and Flying the Nose wheel Configuration
In short and per the plans, I have found the Sonerai tri-gear steering is predicable with no bad habits. Ground handling is smooth and the nose wheel absorbs runway/taxiway anomalies very good (I am using the Sonex spring, which I discuss later). Flight characteristics are smooth, with the minor exception of when I added a fairing, as I outline below.
The wheelbase is shorter than probably any plane you have flown, and the first few taxi runs you will say that it is quick. But with practice, you will get use to the quickness and with time, it will be normal for you. I did a lot of taxing before my first flight, but I would have regardless of nose or tail steering. Just watch your engine temps if you do. I found the high speed taxi tests to be very valuable for steering, braking, and alignment testing not to mention getting use to the attitude looking out of the plane when you are on the ground. This is true for either configuration, just you will need to do the alignment and steering adjustments before the first flight. One easy way to check alignment, taxi down a taxiway line and shut down. Get out and view your rudder from behind, as it is easy to see if the rudder is out of alignment. And you want to make sure you do not get a “wobble†from your nose assembly, which is another good reason to perform high speed taxi tests. For me, it did not happen often, but in my first 20 hours it happened a few times. It is a light shake that gets stronger until you slow the plane down. I have found a wobble is attributed to one of three things: The correct tautness of each steering cable attached to the nose assembly; the nose wheel axle being tight enough to allow the wheel to spin freely, but no looser; the correct nose wheel pressure.
I flew my plane without a nose wheel fairing for the first 40 hours. I noticed no yaw tendencies caused by the nose wheel. After adding a nose wheel fairing, I did notice a yaw/handling difference. It was a distinct yaw to the left, which effected both my rudder pressures during a turn and the need for constant right rudder during cruise. Bottom line, I adjusted the nose wheel steering cables until I achieved zero rudder pressure required at cruise speed. All flight maneuvers are now predictable, but there definitely an effect attributed to a nose wheel fairing. It is not an issue, and maybe it is my specific configuration, but certainly worth mentioning as you may have a similar experience. Note I am using the “standard†fairing, which looks similar to the one used on the LTS prototype.
Minor Modifications/Alterations
I built my LTS to plans with very few exceptions. For the nose wheel assembly, the largest exception is the shock absorbing rubber sleeves. I used a Sonex nose wheel spring, as I believe most tri-gear Sonerai builders use these days. I fit it with no alteration to the spring. The spring takes the place of the two rubber sleeves, the aluminum washer between the sleeves, and the tube spacer that are identified in the plans. I thought I heard John Monnett designed the Sonex spring to also be used on the Sonerai, but I am not sure if that is true. I will say it fits and performs like it was made for the Sonerai. You will position the spring on top of the “multiple tube build up†per plans, and secure/weld that “multiple tube build up†so the plane is level after the spring settles. And when you level the plane, then you know how much of the strut assembly you can cut off for the total length. This is all per the plans, just substituting the spring for the rubber sleeves. Note the Sonex spring needs no alteration. I did buy the rubber sleeves some years back before the Sonex spring was available, and I speculate the rubber sleeves will not perform near as good as the Sonex spring. For hard surface runways, the spring performs very well and to date I have never experienced the spring “bottoming out.†It does not have much travel, but evidently does not need much as it is very effective.
One alteration I recommend is subtle. It is the location of the compression springs, used in the cable system to control the nose steering and keep the cables taught. Per the plans, I could not find the proper compression springs small enough to fit in the location attached to the steering head. Maybe the compression springs available years ago were smaller, but I could not find one that would fit to the steering arm and allow full travel. I first used tension springs that were short enough to allow the travel. But the performance allowed for some infrequent oscillation (wobble, as described previously), and upon full tension I was concerned about failure. So I purchased compression springs through Spruce (P/N 06-15700), and located them at the opposite end of the cable at the passenger rudder. I have found this location and spring to work fine.
A modification I strongly suggest concerns the cable length. I did trial and error with the cable lengths in getting the rudder and the nose wheel to align, per plans. It took me three different lengths in the first 60 hours to get it right. The plans do not call for a turnbuckle (one on each side), but that would allow for some easy cable length fine tuning. The key word is easy, as opposed to cutting/fitting cables to get the desired length. After flying some 40 hours, I installed the nose wheel fairing. I immediately noticed a difference in terms of rudder control in all aspects of flying. The turnbuckles allow to adjust the cables for overall cable tension and comparative tension between the left and right cable. I wound up adjusting the cables to “center the ball†in cruise flight. I would have installed turnbuckles day 1 had I known all of this, and I strongly suggest you consider them. Grams turns into ounces, and ounces into pounds, so the drawback is weight. The other option is to cut/fit cables until you get your desired configuration. Look in my gallery (Wafer; 2nd page), and see the pics of the turnbuckles and compression spring locations.
I do have one addition I suggest. I wanted an ability to easily tow/maneuver the plane by hand per some sort of a tow bar. I did much investigation looking at how fellow EAAers configured their homebuilts and how some of the kits manufactures outfitted their designs. I came up a simple addition of two AN490 rod ends added to the fork, located between the axle and the fairing bracket. The rod ends stay nestled within the fairing, and are used to secure a tow bar for easy handling. You can chose the size rod end to marry up to whatever size tow bar you desire. I just leave the tow bar hooked up until I am ready to fly. I know I have added some drag with the interruption on the front fairing, but the towing ability is really worth it. Look in my gallery, and see the pics.
Landing
My final comment is about how nice this plane lands. Upon rounding out after the runway numbers, the plane slowly quits flying and settles upon the runway. It does not float much. Though the landing characteristics are not due to the nose wheel configuration, after the main wheels touch down the nose wheel takes over and you have that nice view I described earlier with good visibility of your surroundings of the entire airport. I added a YouTube video link below of final approach, landing, and some taxing. Note the nose wheel touches down just before the runway 1000 foot markers. My little Mobius camera is located above my head, located 6 inches above my eye height, and 6 inched forward, so what you are seeing is better visibility than what you actually see when flying…but you get a good idea what to expect.
Hope this helps some of you considering or building a nose wheel Sonerai.
Mike “Wafer†Then
https://www.youtube.com/watch?v=HBa6DO284og
Tail dragger vs. Nose wheel Configuration
First, please do not consider the tri-gear only because you do not have tailwheel experience. In order to get some stick time, and I do suggest you should obtain stick time before flying a Sonerai, chances are you will fly a taildragger. You will probably find that flying a taildragger is not extremely difficult. It is more technique to learn, and more tasks to get proficient, but certainly obtainable with time and practice. Besides sport plane aesthetics (tail draggers do look better), to me the biggest advantage of the tail steering design is less drag. Also, tail steering is needed if you plan to do grass strip landing. I am not trying to talk you out of the nose wheel configuration (I love it), just do not discount the tail steering configuration because you have zero tail time.
The most positive attribute the tri-gear configuration provides a real nice view while ground maneuvering. And upon landing, you get to enjoy that nice view right after touchdown. To me, it is the biggest plus for the nose steering design regardless if it is a Sonerai or not. Some call it a safer configuration; others view it as the modern day standard arrangement. Insurance companies consider it less risk, and factor that in the premium. For me, I am just more comfortable with the nose configuration.
Though some may argue looks, the biggest drawbacks of the nose wheel design is the amount of drag produced, and to a degree weight. So let’s just say less performance. How much? The only way to really make that comparison is with the same aircraft flown in the two configurations. In a March 1983 Sport Aviation article on the tri-gear design, Monnett Experimental Aircraft’s performance testing yielded 2-3 mph lower at top level speed at 75% cruise. To date, my experience with top speed has been below expectations. Not a disappointment, just not as fast as others obtain. As my plane is a heavy at 650 lbs. empty, and I am another 210 lbs., I am sure there are other factors other than the nose wheel configuration that yield my 125 mph CAS at 24 inches manifold pressure performance. Maybe I have some more speed tweaks I have yet to discover, but that is my experience to date. If squeaking the most performance out of your bird is your main goal, maybe the tri-gear is not for you. Is the tri-gear a “dog?†Maybe in comparison to a light, powerful Sonerai 1, but otherwise hardly not. My plane takes my breath away every flight. Just consider you will lose some performance.
The other drawback is soft field operations, as soft field is not recommended. I do not know the details why, just that it is not recommended. This maybe a show stopper if soft field ops are your normal intentions.
Taxing and Flying the Nose wheel Configuration
In short and per the plans, I have found the Sonerai tri-gear steering is predicable with no bad habits. Ground handling is smooth and the nose wheel absorbs runway/taxiway anomalies very good (I am using the Sonex spring, which I discuss later). Flight characteristics are smooth, with the minor exception of when I added a fairing, as I outline below.
The wheelbase is shorter than probably any plane you have flown, and the first few taxi runs you will say that it is quick. But with practice, you will get use to the quickness and with time, it will be normal for you. I did a lot of taxing before my first flight, but I would have regardless of nose or tail steering. Just watch your engine temps if you do. I found the high speed taxi tests to be very valuable for steering, braking, and alignment testing not to mention getting use to the attitude looking out of the plane when you are on the ground. This is true for either configuration, just you will need to do the alignment and steering adjustments before the first flight. One easy way to check alignment, taxi down a taxiway line and shut down. Get out and view your rudder from behind, as it is easy to see if the rudder is out of alignment. And you want to make sure you do not get a “wobble†from your nose assembly, which is another good reason to perform high speed taxi tests. For me, it did not happen often, but in my first 20 hours it happened a few times. It is a light shake that gets stronger until you slow the plane down. I have found a wobble is attributed to one of three things: The correct tautness of each steering cable attached to the nose assembly; the nose wheel axle being tight enough to allow the wheel to spin freely, but no looser; the correct nose wheel pressure.
I flew my plane without a nose wheel fairing for the first 40 hours. I noticed no yaw tendencies caused by the nose wheel. After adding a nose wheel fairing, I did notice a yaw/handling difference. It was a distinct yaw to the left, which effected both my rudder pressures during a turn and the need for constant right rudder during cruise. Bottom line, I adjusted the nose wheel steering cables until I achieved zero rudder pressure required at cruise speed. All flight maneuvers are now predictable, but there definitely an effect attributed to a nose wheel fairing. It is not an issue, and maybe it is my specific configuration, but certainly worth mentioning as you may have a similar experience. Note I am using the “standard†fairing, which looks similar to the one used on the LTS prototype.
Minor Modifications/Alterations
I built my LTS to plans with very few exceptions. For the nose wheel assembly, the largest exception is the shock absorbing rubber sleeves. I used a Sonex nose wheel spring, as I believe most tri-gear Sonerai builders use these days. I fit it with no alteration to the spring. The spring takes the place of the two rubber sleeves, the aluminum washer between the sleeves, and the tube spacer that are identified in the plans. I thought I heard John Monnett designed the Sonex spring to also be used on the Sonerai, but I am not sure if that is true. I will say it fits and performs like it was made for the Sonerai. You will position the spring on top of the “multiple tube build up†per plans, and secure/weld that “multiple tube build up†so the plane is level after the spring settles. And when you level the plane, then you know how much of the strut assembly you can cut off for the total length. This is all per the plans, just substituting the spring for the rubber sleeves. Note the Sonex spring needs no alteration. I did buy the rubber sleeves some years back before the Sonex spring was available, and I speculate the rubber sleeves will not perform near as good as the Sonex spring. For hard surface runways, the spring performs very well and to date I have never experienced the spring “bottoming out.†It does not have much travel, but evidently does not need much as it is very effective.
One alteration I recommend is subtle. It is the location of the compression springs, used in the cable system to control the nose steering and keep the cables taught. Per the plans, I could not find the proper compression springs small enough to fit in the location attached to the steering head. Maybe the compression springs available years ago were smaller, but I could not find one that would fit to the steering arm and allow full travel. I first used tension springs that were short enough to allow the travel. But the performance allowed for some infrequent oscillation (wobble, as described previously), and upon full tension I was concerned about failure. So I purchased compression springs through Spruce (P/N 06-15700), and located them at the opposite end of the cable at the passenger rudder. I have found this location and spring to work fine.
A modification I strongly suggest concerns the cable length. I did trial and error with the cable lengths in getting the rudder and the nose wheel to align, per plans. It took me three different lengths in the first 60 hours to get it right. The plans do not call for a turnbuckle (one on each side), but that would allow for some easy cable length fine tuning. The key word is easy, as opposed to cutting/fitting cables to get the desired length. After flying some 40 hours, I installed the nose wheel fairing. I immediately noticed a difference in terms of rudder control in all aspects of flying. The turnbuckles allow to adjust the cables for overall cable tension and comparative tension between the left and right cable. I wound up adjusting the cables to “center the ball†in cruise flight. I would have installed turnbuckles day 1 had I known all of this, and I strongly suggest you consider them. Grams turns into ounces, and ounces into pounds, so the drawback is weight. The other option is to cut/fit cables until you get your desired configuration. Look in my gallery (Wafer; 2nd page), and see the pics of the turnbuckles and compression spring locations.
I do have one addition I suggest. I wanted an ability to easily tow/maneuver the plane by hand per some sort of a tow bar. I did much investigation looking at how fellow EAAers configured their homebuilts and how some of the kits manufactures outfitted their designs. I came up a simple addition of two AN490 rod ends added to the fork, located between the axle and the fairing bracket. The rod ends stay nestled within the fairing, and are used to secure a tow bar for easy handling. You can chose the size rod end to marry up to whatever size tow bar you desire. I just leave the tow bar hooked up until I am ready to fly. I know I have added some drag with the interruption on the front fairing, but the towing ability is really worth it. Look in my gallery, and see the pics.
Landing
My final comment is about how nice this plane lands. Upon rounding out after the runway numbers, the plane slowly quits flying and settles upon the runway. It does not float much. Though the landing characteristics are not due to the nose wheel configuration, after the main wheels touch down the nose wheel takes over and you have that nice view I described earlier with good visibility of your surroundings of the entire airport. I added a YouTube video link below of final approach, landing, and some taxing. Note the nose wheel touches down just before the runway 1000 foot markers. My little Mobius camera is located above my head, located 6 inches above my eye height, and 6 inched forward, so what you are seeing is better visibility than what you actually see when flying…but you get a good idea what to expect.
Hope this helps some of you considering or building a nose wheel Sonerai.
Mike “Wafer†Then
https://www.youtube.com/watch?v=HBa6DO284og