Tony__L

I have a similar issue at hand and I am trying to figure this out for my own plane. Generally, on shorter flights (1 to 1.5 hrs and less) I find that the tach is about 10-15% over reading on the clock. On longer flights this comes down a bit but still over reads. Seeing that I tend to fly at low power settings (24/2400 and less depending on altitude) I would expect that on longer trips (anything over 1.5 hrs) that the tach should in fact be lower than the flight time. I do not have a hobbs meter in the plane. My plane is in for annual maintenance at the moment and we are trying to look into this issue. From what we can figure out it would seem that the tach in the plane could be the original equipment, we think this only because the hours on the tach equates closely to the air frame time. However, we cannot find an actual spec for the tach. I was hoping that some of the folk on this forum could assist in perhaps figuring out at what RPM my specific tach is supposed to be accurate. The details as gleaned from the back of the instrument are as follows: “Patented Made in USA.” “A.C. DIV.G.M.C” “FLINT, MICH” “64.121.10” “91103’ ( this is not clear at all) My plane is a 1967 M20F Executive. Is there a resource that would tell me what tach should be installed in the plane and what the spec of that tach are? Knowing this and the specs of the tach above I will then be able to compare them and see if I must just live with the situation as it is or rectify it. Any assistance would be great! Tony

Bump! I'm looking for 500 views of my video. Please share it on your Facebook profiles

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Yes awesome country!

I plan on collecting some nice footage over the upcoming holidays and hope to make a really nice video out of it.

SA does have nude beaches, that's why we fly the coast, to look for them

I recently posted a video about a holiday along the West Coast of South Africa. I actually live on the East Coast and regularly take scenic outings along the coast. Last weekend I took a young lady and her mom for their first flight ever. The weather was fantastic and the vegetation wonderfully green from recent rains. The footage was too nice to cut much out so I sped up the video so you can see as much as possible in a 'reasonable' length video. Enjoy!! http://youtu.be/7N3n42diBwo Remember to hit the like button (in YouTube and Mooneyspace ) if you enjoy the video.

Hey Jeff, That is a bit rough . . . . . but very true

This is a short video that I made of a trip we did with 5 planes in April this year. The planes were a wonderful mix and comprised a Jabiru 170, Kitfox, Glassair Sportsman, CTSW and my Mooney M20F. All of the planes originated from the East of the country, so the first leg was to 'commute' to the west. We then flew up along the west coast of the country and returned via a northern route (see JPG and KMZ files attached). In total it was a 9 day trip with fantastic weather and friends. The video is more a personal reflection for the group that went but for those not familiar with South Africa there is nice taste of the landscape we call home. Flyaway Legends West Coast Tour.zip http://youtu.be/Yg0IUNvmJ7k

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Emergency escape \\//

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Hi Lood, Thanks for the data. Interesting exercise reducing to LOP FF to see performance. The speed decrease is rather dramatic. This aspect of this thread has been extremely interesting to me and has added another dimension to flying for me. Tony

Heat gun can be very aggressive and could damage the paintwork. I used a hair dryer with good results, just takes longer. Suction mounts are risky in aviation. They work on the principle of differential pressure, so when you climb to around 6000 to 8000 ft above the elevation where you mounted it, it will fall off. You would have seen this happen if you use a windshield suction mount for a portable GPS in the cockpit. I have mounted the camera on the wingtip before using a screw from the Nav light lens for insurance. Worked well with lots of peace of mind. Tony

Done and more than happy to do so! Keep up the good work!

Wow, looks fantastic!!!

Fantastic upgrade! Nice improvement!

Hi Lood, I can also claim VAT on my Avgas and my engine runs cool too, but a saving of 32% in fuel burn for a sacrifice of 4% loss in speed is hard to turn down. Let's put some real world figures to this. Flying to CT at FL065 (as I did last week) at 100 ROP would have taken 3.31hrs and 146 L of avgas. At 10 LOP it would have taken 5.6 minutes longer and I would have saved 33 L of avgas. At 33 L per hour at 10 LOP that means that I get a whole free hour of avgas for my next trip To answer your question, no I haven't performed your proposed exercise yet (will try it next time out). However, I fly with a bunch LSA aircraft on trips that we do and I will occasionally loiter with them at around 100kts. I always end up with much the same fuel burn as they have, around 20 Lph at a ROP setting. This is very economical but you lose out on the maintenance costs on the other end of the equation (my tach turns slightly faster than the clock all the time, no matter what the power setting is ). Tony

Rags, Something I forgot to mention in my response to you questions. My engine is at +/-800 SMOH (factory overhaul) but is a 4000+ hour total time engine. Tony

Rags Thanks for the comment on the graph, it took a long time to get it readable for those that didn't put it together. Was still worried that it was too much. Just another comment on the data, there is a gap between FL065 and FL095. This was due to unfavorable winds at higher or lower levels for the route either on the way to CT or on the way back. Being a 490NM trip meant that I did not want to spend time in a head wind for the sake of collecting data. I will add to the data as and when the opportunity arises to fly at the 'missing' levels. With respect to mods on the plane; I still have the original split windshield. It has the cowl front end enclosure mod, gap seals at the wing roots, wing tips (M20J style), the step has been removed and minimal antennas. The paint is newish and I gave it a full compound polish earlier this year (I don't believe it myself but I believe that alone added 2 to 3 kts). I don't have ram air anymore, not sure of why it was removed, I think it might have something to do with the cowl closure and the air filter position. I also have a 3 blade prop which doesn't help with speed but boy oh boy can I beat the POH figures on take off. I also have a draggy wheel at the moment, see my thread on this, but will hopefully get this sorted out the next time the plane goes in for maintenance. I know we calculate the weight of the plane relative to MAUW but nonetheless I think that my planes empty weight is quite light for such an old plane. The last time it was weighed it came in at 1817 lbs. I did see a figure somewhere, but I can not find it at the moment, that showed that the plane was heavier when it was new. Also note that I was calculating TAS using pressure altitude, OAT and indicated airspeed. I have found that this seems to produce 2 to 3 kts higher results than the 4 or 3 point GPS method. Tony Tony

Did a trip to Cape Town last week and had plenty of time (on the way there at least, on the way back had to 'fly' the plane the whole way back because of turbulence) to test a whole lot of mixture settings and get some data together. In summary I found that at anything more than 10 LOP you loose a lot of speed. Your MPG improves a little but I would guess that the extra fuel saved is spent again in maintenance due to the extra time spent in the air. I also found that at anything below 2500 RPM the loss in speed is drastic when getting to Peak and even more so when moving to LOP. So much so that I did not bother trying out 30 LOP at 2400 RPM. I have showed some 2400 RPM data in the data table but not on the chart. After this exercise I think that 2500 RPM and 10 LOP is a sweet spot. The CHT's are lower than ROP and fuel burn improvement is substantial. The improvement in fuel burn and the negligible change in TAS as you fly higher is quite impressive and confirms the talk about flying higher to get better figures all around. Below is the RAW data and a chart that I put together. The chart is quite busy but very legible when you print it. I had to change some of the typical reporting formats to make it readable (e.g. NM/10gal instead of NM/gal). Have a look and let me know what you think. PerformanceChart.pdf PerformanceData.pdf

As mentioned on Avcom, nice job!!! Now it is time to get the Mooney's together in SA!

Rags, I also have GAMI injectors and use a JPI EDM 700 to lean accurately. I however was leaning the richest cylinder to 30 degrees LOP and not 10 like you (is there a reason why you choose 10?). I was also,doing this at lower levels, 4000 ft indicated and probably around 5000' DA. According to the POH at 5000' and 25/25 or 24/24 at best power mixture you are running well over 65% power, more like 82% and 77% respectively. So,I probably wasn't being very wise trying LOP at that altitude and power setting configuration (although I suspect that at LOP the power produced drops radically). I will be doing a trip to Cape Town this week and will be at the higher levels and will try a bunch of different power configurations and will see what the data shows. Lood and Bob, I'm glad to see that you experience similar loss of speed to me. Tony

Anyone got any data on speed loss when comparing ROP versus LOP ops at the same power settings? I am finding around 10-12kts slower at LOP versus ROP and wondered if that was normal.