Engine options

[Glennlawson]

Good evening everyone,asking for some ideas I’m now looking at the hirth f23 I like the Hp to rpm ratio and the tbo recommendation. Draw back the fuel burn. My question is I can do the experimental route.is there a larger fuel tank option to get into 2-3 hours of usable fuel

[Mountain Cat]

Two wing tanks will give you 10-12 gal. I bought a couple from Stace a couple years back. And my kit had one with it. The Chinook used 2 strut mounted tanks 5 gal each. That would be an option for longer trips and easy to remove for local flying. Wing tanks are out there, new and used. Just takes a little research.

[Badland-F5 Pilot]

Good evening everyone,asking for some ideas I’m now looking at the hirth f23 I like the Hp to rpm ratio and the tbo recommendation. Draw back the fuel burn. My question is I can do the experimental route.is there a larger fuel tank option to get into 2-3 hours of usable fuel

So you're talking about getting the plane registered as an experimental LSA? If yes, then yes you can go with a larger fuel tank. I'm not sure what the limit on LSA is or if there is any.

I also like the F23. It is my current engine of choice. Also, just like you, I'm concerned about the fuel consumption. I'm still looking at options to help this issue. First is installing a ground adjustable variable prop and tuning for best cruise when needed. The other and I think it'll have a much bigger change in fuel use is replacing the stock carbs with Smart Carbs.

From the Smart Carb website -

What fuel economy gains can I expect?
On average SmartCarb users should expect a 30% increase in fuel economy compared to the stock fuel system in the same conditions (riding style, speed, terrain, elevation, etc). Oil injected Beta customers can expect a 40% increase in fuel economy.


How will the SmartCarb affect power delivery?
The SmartCarb is a high performance fuel system that will increase horsepower and torque throughout the entire throttle range. You can expect more power delivered more linearly due to the SmartCarb’s single circuit fueling and variable venturi throttle rate. Properly tuned, the bottom end throttling is best described as being crisp, clean, and responsive with a smooth, linear transition through the mid into a forceful top end, extending the power-band a further 500-600 useable RPMs. We guarantee 10% more peak power compared to the stock fuel system.

I've watched a lot of YT video evaluation of the SC2's used on both 2 and 4 strokes. In every video I've seen, the evaluators have stated that the numbers Smart Carb advertises are pretty much dead on. One other thing, smart carbs' auto adjust fuel mixture for altitude. The big problem is that we'll need two smart carbs, and they aren't cheap!

If interested, here's the URL for their website - https://smartcarbfuelsystems.com/

Todd

[Glennlawson]

I also was looking into the smart carb upgrade with a 3 blade adjustable prop thinking that it might reduce the rpm a little while adding a little extra thrust. Also wondering what instruments are available thru badlands basic 6 pack with a I pad and flight app. And a hand held com with head set. I’m thinking that I will have as much fun building as flying

[Badland-F5 Pilot]

I’m thinking that I will have as much fun building as flying

EXACTLY one of the best things about Part 103. Even an LSA experimental still has to deal with getting the FAA's approval on installing or modifying many additions to their planes. We don't have that issue!

Peer and I have been talking about this very thing, that much of the enjoyment is being able to make the planes very versatile and change it up based on the type of flight planned. Going on a good cross-country? Configure for best fuel burn, good navigation tools, and smooth flight. Going camping, get those large tires on, and go with STOL in mind, some items won't be needed so drop the weight, and set the prop to pull like a bull. How about just a nice hop around the patch one evening, nothing major required in the plane, set up with what's needed and enjoy the late afternoon, early evening air up there! Maybe even have some pop on/off lights extending the flight into dusk.

We have a lot of options that can be changed in a snap, and we don't have to worry about someone from the FAA approving our change. I suppose Part 103 can really be called true experimental flight.

Peer already has VG's on his plane. I plan on adding them on mine. Grabbing a little extra STOL capability without suffering any cruise speed sounds like a good thing to me.

There are so many options available. I'm looking forward to getting my kit.

Todd

[Mountain Cat]

There is no more experimental/LSA category unless the factory builds an LSA/factory built. All of the ones now are Experimental/amateur built. And with that category we are not limited to what we can add/ remove or change. If it would happen to be a major change, we have to go back to phase 1 for 5 hours. In the E/AB world we are still free to experiment at our risk. That is once the airworthiness certificate is issued and we fly off phase 1 time. Pt 103 is even less regulated than that. I am all for Pt 103 if one can make weight.

[Badland-F5 Pilot]

That makes sense since I saw Trent Palmer put a different set of brakes on his KitFox, and could still fly; but no passenger until going through the procedure you mention for FAA approval. Thanks for clarifying. I do like the flexibility Part 103 provides. I wish we could carry more fuel is my only real disappointment with the rules.

Todd

[Mountain Cat]

Could anyone tell me the recommended idle speed for the polini 303? I can't seem to find it in the manual. Thanks

[Badland-F5 Pilot]

Could anyone tell me the recommended idle speed for the polini 303? I can't seem to find it in the manual. Thanks

I believe there is no posted idle RPM because that will vary based on the propeller mounted to the engine along with the torque clutch that controls when the propeller actually engages. With this, I've seen props rotating at 0 to around 60 (general observed best guess) RPM. Personally I would like the prop to be at a complete stand still at idle. This most likely is possible with a wooden prop, but something tells me that a carbon fiber prop is too lightweight, and will rotate at a very low RPM, but never stop.

[ksatter26]

At this point, still awaiting a CDI replacement for my factory new 303, I just hope to get it to start.

[Mountain Cat]

Thanks! I did start it this morning and it idled at about 1100-1200 smooth with the prop just barely turning.

[LA F2 Flyer]

That sounds like a pretty reasonable idle speed, provided it's smooth. Maybe let it idle for a while and watch the temps, then check the plug for fouling. It might be a good way to determine if there are any downsides to the current idle speed.

[Badland-F5 Pilot]

That sounds like a pretty reasonable idle speed, provided it's smooth. Maybe let it idle for a while and watch the temps, then check the plug for fouling. It might be a good way to determine if there are any downsides to the current idle speed.

Agreed and maybe go through a quick idle to med, med-high RPM to make sure there's no hesitation or cough. Not balls to the wall type of throttle up, but just a quick increase to make sure that's also smooth from that idle RPM.

[Mountain Cat]

Having an issue with getting the Polini gauge that Chris sent to work properly. It seems designed for a motorcycle and doesn't really work very well for an aircraft engine. Going to try to convert it to some other type of EIS. Trying to figure out if Polini's probes are J or K type.

[ksatter26]

Checking my on- line purchases, I got K-type female thermocouple connectors from MN Instruments ... back in the 1st week of January. As I remember. I had to do a lot of research. I hope this helps.

[Mountain Cat]

Thanks a bunch. Most USA ones are J and won't cross match. K type are a little more accurate.

[Mountain Cat]

Did get the EGT working, now for the CHT. Will only use the Polini gauge for the tach and water temp. Of course a Tiny Tac works extremely well, also and a lot cheaper. Water temp I can modify to work with a steam gauge and do away with the Polini gauge altogether. Thanks for the answer.

[Badland-F5 Pilot]

Peer, do you think this is the same problem you're having with your EGT?

Todd

[Mountain Cat]

Westberg or Westach gauges work with K probes. Not sure about the China imports. Evidently Polini doesn't use a CHT with the water cooled engine, even though they send the probe ring. I can find no CHT limits in the manual and the Polini gauge will max out at 482 degrees. So it won't be used unless one wants to use stand alone gauge in the panel. The EGT will not work with the Polini gauge either. Since it runs 1000 deg +, it maxes out the Polini gauge instantly. I tried my Westberg gauge with the EGT probe and it worked. I am almost to the point where the Polini gauge is going in the trash and use standard gauges for everything. Being an old school A&P, I can work with steam gauges.

[LA F2 Flyer]

Hey Todd - My EGT works (as shown by me testing it off the plane). I think the issue with mine is that the bung for the sensor is too far from the exhaust port - roughly seven inches. I've since moved the sensor much closer to the exhaust port and welded over the hole they provided. I still need to test it, but I have high hopes!

[Badland-F5 Pilot]

Hey Todd - My EGT works (as shown by me testing it off the plane). I think the issue with mine is that the bung for the sensor is too far from the exhaust port - roughly seven inches. I've since moved the sensor much closer to the exhaust port and welded over the hole they provided. I still need to test it, but I have high hopes!

My fault, I didn't explain myself better. I was wondering if possibly the different type of sensor would have worked in the original mounting hole in the exhaust pipe instead of having to make a new hole closer to the exhaust port of the engine? I wonder if one is more or less sensitive or reactive to the heat from the exhaust? Of course this really won't make any difference if you go with the 4 stroke. Sorry on the confusion.

Todd

[LA F2 Flyer]

Oh, that's a good point. Polini (in all of the wealth of information provided with their engines) doesn't require their EGT that I am aware of, but I could be wrong about that.

I would think, though, that a sensor is a sensor, and should accurately read the temperature at the point of the sensor itself, if that makes sense.

[Badland-F5 Pilot]

I would think, though, that a sensor is a sensor, and should accurately read the temperature at the point of the sensor itself, if that makes sense.

I was wondering about that because Mountain Cat said the following "Most USA ones are J and won't cross match. K type are a little more accurate."

Are the J and K type the probe in the exhaust manifold or are they the instrument itself? I'm thinking these are two different types of probes, so they may not work entirely the same?

[Mountain Cat]

Polini does use an EGT, they don't normally use a CHT on a water cooled engine. The EGT is used to adjust to the proper mixture(correct jet) to keep EGT's in limits. CHT is really controlled by the water temp. I like EGT, CHT and water temp gauges in the panel. You lose a coolant hose and it will show on the CHT almost instantly. And yes they are "J" and "K" probes and gauges for each. The most common is J probes/gauges. My Westach gauge is marked "use K probe". Nothing is simple in the aviation world anymore.

[Badland-F5 Pilot]

Polini does use an EGT, they don't normally use a CHT on a water cooled engine. The EGT is used to adjust to the proper mixture(correct jet) to keep EGT's in limits. CHT is really controlled by the water temp. I like EGT, CHT and water temp gauges in the panel. You lose a coolant hose and it will show on the CHT almost instantly. And yes they are "J" and "K" probes and gauges for each. The most common is J probes/gauges. My Westach gauge is marked "use K probe". Nothing is simple in the aviation world anymore.

OK, that makes sense - but of course leads to other questions What are the differences in the J and K probes? Are they different sizes or is there more too it? I'm curious because when Peer was setting his EGT up, the reading was almost nil, no real movement of the needle. He had to drill a new hole for the probe up closer to the exhaust port on this Polini 202 (pre-water cooling). He ended up welding the hole that Polini had put in the original stock exhaust. Once done, his EGT now reports. That opens a new question - where should the J or K probe be in relations to the exhaust port on the engine? Where is the best place on the exhaust to measure (accurately) the exhaust to tuning of carb can be done properly?

Thanks,
Todd

[Mountain Cat]

As a guide, Rotax specifies 100MM from the piston face. Polini's might not be the same distance. I didn't measure the Polini port distance, but their EGT temp limits are different from Rotax. The location of the probe is important to get the correct temp limits. Polini can stand a little hotter temps than Rotax due to the nickcil cyl and piston. The Rotax use a steel sleeve and an alum piston, they expand at different rates and limits. Polini uses the same material for the piston and cyl so they expand at the same rate and limit. That is my complaint against Polini, they don't publish the engine info that A&P's want to know. There is a good chance that he matched the probe w/ the correct type of gauge. But we are talking about a very, very small amount of voltage to operate the gauge so several things could have been the issue. Only Polini will have the correct information on the distance they specify.

[Mountain Cat]

The difference between J and K probes is the type of material and construction. sizes are similar.

[LA F2 Flyer]

The problem with my Polini (as I see it) is that there is plenty of documentation regarding the acceptable range for EGT temps, but zero documentation advising where the sensor should be.

I based my placement on what other people have posted on the paramotor forums. Is it correct? I have no idea. But their experience would suggest that I should be safe with the sensor placed where I have it currently. I made the assumption that it was meant to be placed where I originally had it, since there was a small ring welded to the exhaust with the same inner diameter as my sensor. It was the only thing added to the exhaust aside from the brackets for the retainer springs. But, as Todd mentioned, it seemed to be far enough away from the port that it didn't register at all.

[Mountain Cat]

Once you get the mixture set, per the color of the plugs, then the EGT reading is just a reference point where you can see if something changes. The plugs are the true sign since they live where all the action it taking place. Not so important as to the exact number as it is to see it climb or decrease quickly. Such as an air leak, clogged air filter, stopped up jet or filter.

[LA F2 Flyer]

Understood, but from what I hear it's pretty hard to accurately read plugs due to the ethanol content here in California. Truth or myth?

[Mountain Cat]

Plugs will still show what you need to know. Unless you have E85 then all bets are off. E10 will pretty much read normal. Running lean causes major problems.

[Badland-F5 Pilot]

Plugs will still show what you need to know. Unless you have E85 then all bets are off. E10 will pretty much read normal. Running lean causes major problems.

Though both Peer and I have a great deal of experience with two stroke engines, those are mostly bike engines. Question, since many of those engines played with were back in the 80's and prior,

1) How long a run on is needed to get accurate plug coloring on modern day engines like the Polini?

2) Should runs also be done at different RPM's to see how the mixture changes through the RPM range?

Thanks,
Todd

[Badland-F5 Pilot]

I admit, at this point I'm now leaning away from the F-23 and more to the Thump Air. My only concern is that the TBO is shorter than I would like. However I believe this is still in testing and could be extended. The loss in HP though I believe is compensated for in much better torque and more important, reliability and lower fuel consumption. Plus, currently the Thump Air is a good $4,000 less than an F-23, and slightly lighter! Four strokes are simply not as finicky to tune in my opinion.

[Mountain Cat]

I think the Thump-Air could be a winner given some real world testing. And that is taking place now from what I hear. All engines go through a teething process so a few issues will always pop up. The Hirth is a good engine but overpriced.

[Badland-F5 Pilot]

The Hirth is a good engine but overpriced.

Exactly one of my top issues with it. I do love the design, HP, and TBO. The price...ouch!

[Mountain Cat]

Been reading some of the replacement time on the Polini 303. With the info I have, I would consider the 303 a high maintenance engine. Replace the piston at 150 hrs, basically rebuild the engine by 300 hrs. Stuff you don't learn till after you buy it. It might go longer and it might not. My thought has always been, fly the engine to TBO, and then replace it with a new one.

[Badland-F5 Pilot]

I agree. I would expect an engine (properly taken care of) to run perfectly to TBO and even beyond, barring any manufacturing defects. I don't think I should have to replace any non-regular service parts before that time. A piston to me does not fall into that category. Thanks for the info on the 303. To TBO and rebuild or replace makes sense. The 303 would be like buying tires that promise 70,000 miles but only if they are retreaded every 15,000!

[Dobie]

I’m still at the dreaming and scheming stage of acquiring a UL. A question of great importance is how will any of the higher HP & Torque motors work for me where takeoff altitude will be at or near 3000 Ft MSL? The plane I would build will be near max Part 103 weight and I’m about 180lb dry. Will I have enough power when I’m just leaving the ground at an altitude a lot of folks operate at or under?

[Badland-F5 Pilot]

I’m still at the dreaming and scheming stage of acquiring a UL. A question of great importance is how will any of the higher HP & Torque motors work for me where takeoff altitude will be at or near 3000 Ft MSL? The plane I would build will be near max Part 103 weight and I’m about 180lb dry. Will I have enough power when I’m just leaving the ground at an altitude a lot of folks operate at or under?

Much more important than engine hp/torque will be the design of the wings/plane itself and material used. In very basic terms though, more hp/torque is not a bad thing to have. Being at 3000 ft msl also isn't going to be a problem. It's the density altitude that may cause you some issue. Such as near me is Rockwall County Muni. It sets at just above 536 ft MSL. With today's 103.3 temp, pressure of 29.9 and dew point of 66.9, an airplane will see an altitude of 3096.4 ft. That's far from the actual altitude of 536 ft of the airport. Most UL's are near the maximum weight for Part 103, so you won't have any issues that are unusual compared to other UL's. I'm around 220 Lbs and can tell you that you won't have any issues at 180 Lbs at all. Looking at Badland UL's, one of our members has one that's around 243 Lbs. He also weighs in around 180 Lbs. He's not going to have any issues with getting off the ground, and actually getting off the ground isn't so much of a problem. It's climb rate that becomes a problem. Most UL's have a total gross lifting capability of 550 Lbs. All that means is that the climb out at 464 Lbs (254 Lbs UL, 180 Lbs Pilot, and 30 Lbs of gasoline) will be much better during lower temperatures than at higher ones.

Is the area you're in at 3000 feet mountain or just high fairly level land? Trees or few trees?

Todd

[Dobie]

Todd, I’m in Central Oregon. Flat/rolling ground that’s largely grasslands and juniper, and rocks. Also a fair amount of hayfield and other friendly emergency landing areas. The surrounding mountains and bluffs are rugged and treed with juniper and pine. Not ideal engine out territory.

[Mountain Cat]

Get an engine you can trust (as best as possible), learn to do the maintenance, and take care of it. Engines rarely fail, they are murdered by their owners. Most aircraft engines are put in the most extreme conditions and pushed to their limit, yet still keep going. The old saying " two types of pilots, ones who have had a failure, and those that are going to". Isn't really true, but, always plan on it. Flying is risky, but you can lessen the odds in your favor.

[LA F2 Flyer]

Dobie, it sounds like you are in a good place for a UL. Plenty of places to put down if you need to, at least close to home! Also consider any obstacles you may have to clear at the ends of your runway. Density altitude will definitely come into play in terms of climb rate. As for your weight, I'd say you are on the lighter side of things.

[Badland-F5 Pilot]

Todd, I’m in Central Oregon. Flat/rolling ground that’s largely grasslands and juniper, and rocks. Also a fair amount of hayfield and other friendly emergency landing areas. The surrounding mountains and bluffs are rugged and treed with juniper and pine. Not ideal engine out territory.

You sound like you've got plenty of area to fly without an issue. As Peer mentioned, it may be a slower climb, but the ground sounds like an opportunity to get into ground effect and build a little speed before climbing out. Other than the 'rock', it really sounds like it's going to be a great place to fly.

Todd