AH-1 Cobra Pilot

Lots of weird numbers coming up on this thread. You can make some pretty good estimates as to horsepower and fuel consumption using these. (Keep in mind, the numbers presume roughly stoichiometric flow.): As memory serves me, these are the common Specific Fuel Consumptions for these engine types: Turbine = 0.43, gasoline recip = 0.36, diesel = 0.34. All are in lbm/hp/hr. As you can see, recips are 20-25% more efficient than turbines for the same horsepower. The big difference is that turbines lose less capability at high altitudes. You can also make your own estimations, such as this. "I doubt it’s making 450HP if it’s only burning 17GPH." Absolutely correct. 17 gal/hr * 6.8 lbm/gal ÷ .43 lbm/hp/hr = 269 hp. (I use 6.8 lb/gal for jet fuel. There may be some fudge to that.) You can also use this to correlate your fuel burn with your presumed %-power. i.e. a J-model at 75% power should burn...150 hp * .36 lbm/hp/hr ÷ 6 lbm/gal = 9 gal/hr. Again, this is best-case-scenario. If you run rich, your results may will vary. I think a little Math can make us all better pilots. Please try it for yourself. P.S. I may be too low on the recips. This gives 10 gal/hr for the J-model, if you accept the number for the IO-720 here: https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

I use 37:1 compression ratio, so better thermal efficiency. Then, I have a long expansion stroke, and very little reciprocating mass. Gasoline actually has a higher energy density than diesel. 20260 BTU/lbm vs. 19110 BTU /lbm. Diesel has more energy/gallon, though, 138110 vs. 116485 BTU.

No, nothing like the Wankel. I use separate compression and combustion epicycloidal chambers with a sliding vane in each.

They are probably exaggerating a little. That yields a SFC of 0.28 or 0.327 lb/hp/hr, (depends on your presumed fuel density). A good Caterpillar diesel gets about 0.34 @ 1050 rpm. https://s7d2.scene7.com/is/content/Caterpillar/LEHW0058-00 If you are truly interested in higher powered engines, I have a rotary engine patent, and I even wrote my Masters Thesis on its analysis. A 127 cu in engine turning 2700 rpm should produce 380 hp @ 2.4 gph. If you have $2,000,000 to invest, (I guarantee a return between 0 and 50,000%), please PM me.

As an entrepreneur/small business owner, I see this kind of thing all the time...It was designed and built by guys with good electronics skills and lousy plastics knowledge. The Tg was obviously too low, but they were in such a hurry to get it to market, they did not do diligent research.

That is interesting. I would have thought it would be the opposite, since O2 has a molecular weight of 32 vs. 28 for N2. I always thought the selling point for pure nitrogen was the avoidance of oxidation inside the tire.

Here you go. https://www.barnstormers.com/classified_1299752_Bede+5B.html

Are you looking to drill a hole in your windscreen? I have seen that done on other aircraft, and it seems to work well. It is also the first place to catch ice, so it makes a good warning. It would scare me to risk a windscreen crack, though. Some boob mounted my OAT probe on the aluminum baffle right in front of the right-front cylinder. (Pun intended.) I constantly get readings that I know are too high. My mechanic suggested relocating it to another location, but what he suggested as easiest also put the probe where it would constantly snag on anyone checking the oil, etc. Any recommendations as to a new probe location?

Wow. I guess I can charge more than I thought for those switch covers.

No, the aircraft is $400,000, the liability insurance is the other $400,000.

UGH! I just got a quote from a local shop to install a JPI 730 for a total of about $6600. $3600 labor, $445 tax, etc. We are over 1500 from recommended TBO, so lots of life before we replace the engine, too. All the comments above have convinced me I should have one, but there is also the need to replace the GX-60 with a GTN-650/equivalent and add ADSB-out. Maybe all at once in another year or so... When do you estimate shop schedules will get tight with ADSB work prior to the 2020 deadline?

Mine is hardwired with the terminal coming out the same hole as the GPU/APU/External Power plug. All you have to do is open the little, spring-held door.

I had to go back to the Engine Monitor topic from a while ago to find this from Bob: "I lose about 6% ktas (155 to 145) while reducing fuel flow by 22%. (10.5 to 8.2)." Doing the Math, this is almost perfect. P=FV, and since F= ½ρSCDV2 , Power depends on V3. So (155/145)3 = (10.5/8.2) = 1.2. A 6% drop in airspeed equates to a reduction of 20% in power, or equivalently, a 20% reduction in fuel consumption.

I guess I kind of mixed terms, taking Economy Cruise as Best Economy. Mine explicitly states ROP. Page 5-23 of POH (Issued 1-96, REV. A 5-97). I also see that we may just be using C vs. F to add to confusion. I will definitely be careful of that.

A couple of things...Best Power may be something different from maximum power.. Note too, that the POH lists Best Power and Best Economy, and that both are ROP. We know even better economy exists LOP. So what is "Best"? That depends. What are you trying to accomplish without busting other limits? Perhaps I should have included the word "possible". Stoichiometric combustion may not be available at all engine settings. It is affected by rpm, timing, etc. The rpm is influential, as the flame speed and piston speed not not coincide. Proper mixing of the fuel and air is also essential for stoichiometric combustion, and again, it depends on many factors, such as injector/carburetor effectiveness, intake geometry,... BTW, my J-model POH shows Best Power at 100 ROP. (?) Is that an engine-model-dependent number?

BSFC is a measurement of efficiency in pounds of fuel used/horsepower/hour, so it may vary by the output of the engine. Power is the Torque x the rpm, (essentially). The shape of the Torque curve will determine where the very best BFSC occurs.

No, Mooneys are efficient because they have so much less drag than other aircraft. The very similar airframes all do well with very different sized engines and beat most other aircraft with the same engines. What everyone needs to understand is that an engine, any engine, is at its highest power when the fuel-air mixture is at the stoichiometric ratio. This means that the fuel and oxygen in the air both burn completely with no residual of either in the exhaust. That should be your 'Peak', and LOP will be less fuel, leaving no fuel, but some oxygen, left over in the exhaust. The worry is that Peak is too hot for long-term engine life. Could your instruments indicate that Peak is not overheating your engine? Sure. Do you want to bet an overhaul on it?... That is the important question. The stoichiometric ratio will vary by the fuel you use. It can even vary slightly between loads of 100LL, but you will probably not notice the difference...maybe from summer blends to winter blends. Regardless, you correct for it via the mixture knob, and unless you mark it, you will never know any difference.

When I used to fly jets, the consensus was that the culprit was almost always during significant power changes. One reason you find the "High" approaches is so the old military jets could stay at altitude until they were close enough to glide the rest of the way. (That and go more than 250 kts as long as possible.) A lot has changed since those days, with jet engines being much more reliable, but I suspect abrupt power changes are still one of the most frequent causes/contributors to dead engines, recips included. Training changed over the years, and I saw too many of my fellow C-12 pilots abruptly pull back the throttles to descend 2000', then abruptly shove them back forward once at altitude. I constantly corrected that behavior, but obviously the training command was not doing a very good job. I once had a power-loss in my P-172. The engine developed carburetor icing due to a hose clamp falling off the carb heat tube. I had pulled the Carb Heat handle, but it did no good.

This is what I settled upon. My co-owner had to whittle off some of the 'prong' to get them in, but they fit quite well. They are very stiff since I used Carbon-Fiber infused Nylon, the paint is not quite as tough as I would like, but it may get better over time, but I will try them to see how durable they are. I will ensure they continue to work for a while before I take orders.

I can. I still have one more idea to test... It may work even better.

They fit tight.

Okay. This is my latest iteration. What do you think of these? These are black CF-Nylon with an off-white paint then laser-engraved.

Too bad the FAA killed this idea...http://reason.com/archives/2017/06/27/how-the-faa-killed-uber-for-planes

" I don't know why my MEDIAN cruise CHT would be at 373°... " It is not Median "Cruise CHT", it is Median "Maximum CHT in Cruise". Out of 18 flights, nine times you cruised with a maximum CHT above 373°, nine times below. That is probably good in its consistency, since nine times were between a very narrow 373° and 387°. Your "Percent Power in Cruise" matches that pretty well, too, as well as your "Speed in Cruise".

The SS may not be what you think it was. Toward the end of the war, Germany recruited lots of French and other occupied peoples to join the SS. They did it willingly in order to fight the USSR troops from the east. In other words, lots of people considered the Soviets a worse threat than the Nazis.