Man, what an endeavor!

Hope they get the engine certified, maybe one day we can toss that in our Twinbos when the GO480's become unobtanium.

Here’s a guess - and only a guess - as to the choice of a liquid cooled engine. One of the truly unique capabilities of the HC is the ability to operate at very low speeds and high angles of attack. Not great for air cooled engines. It could be the business case depends on using that capability for more extended slow flight operation and without solving the cooling problem they have no business case. Still, seems like that engine choice raises their business risk significantly. I hope it works out for them.

As for the crosswind limitation, I believe the 295s had crosswind gear. Not sure about the 700 and 800. That, combined with the ridiculously short landing roll when flown at its limits made the published limitation much less of an issue - according to folks I know that have flown them.

Very impressive. I got a ride in one and later ferried a tricycle gear version. It is an amazing performer once you figure it out. I agree that the high torque long blade combination is a key to the unique performance. There was also an IO720 variant with much more horsepower but direct drive. It was not as popular.

As smart and capable as these guys are, I am sure they have considered going through the initial testing regime with a stock 295HP GO480 to streamline the process with less risk to their prized aircraft and then add the direct drive water cooled engine to the type certificate at a later date. Maybe I will contact them and offer them a good deal on a G2D6 core in case they decide to go that route. I am sure they could recover most of that investment selling it to a Twin Bo owner when they finish with it.

The engine they are developing, if successful, will have multiple applications for retrofits on existing airframes and in the experimental market.

I wish them luck and good fortune.

Looks like they are using this liquid cooling conversion kit for a Lycoming 540 core:

https://044ea3f.netsolhost.com/lycoming/centurion/

Non certified/PMAed for experimental only?

If so, maybe they plan to STC the reconfigured 540 they are utilizing.

Very cool endeavor. On the engine I think they'd be better off just putting in a stock Lycoming O-540.

I watched this while I was working and enjoyed everything about it, but had two thoughts:

1) They're going to have to sell them for a million dollars to make any money. Is there a market for that?

2) Inventing a new engine to make an airframe successful... How often has that gone well for a small company?

I wish them all the best, but this does not seem like a recipe for success.

Wow, what an undertaking. I hope they make it. My only suggestion, get those plans and the rest of the documents to a printer that can scan them and create PDF's. We do it all the time with old building prints. We've lucky, we've got a great print shop nearby.

I hope they are successful.
I had a friend who sold his turbo 206 and bought a H700 IO-720 Helio. He said it was dangerous in the back country of Idaho at high altitude with any load because it could get off short but then just would not go anywhere until you could slowly accelerate enough to get the slats retracted. Then it was fine. Landing no problem. the Geared engine was definitely needed for the larger propeller disk area. So we built him a R-985 Stinson to use. That has worked for the last 12 years but now he has been part of the 1000hp Garrett Broussard project.

I see one H700 was converted to turbine recently. There are some Youtube videos of it.

Just a comparison Lycoming R-680 with 9 cylinders and 680 cu inch is also 300hp at 2300 RPM. It has an impeller that does not spin fast enough to supercharge but does help even out mixture distribution. Single gravity feed updraft Carb.

To make more HP with 140 less cubic inches and the same RPM seems like a lot.

But they could look to Continental back in the 70s with various 2400 RPM redline engines on the 182s and 180s. If using similar cam profiles in a Lycoming IO-580 would it make the HP numbers they need without liquid cooling? Did Continental change cam profiles for the low RPM engines? I've seen the 182 John Jewell STC to increase RPM from these engines but does the cam change also?

R-680-9 about 546 lbs
IO-580 444 lbs.
IO-720 597 lbs. 400hp but too small propeller disk area.
Liquid cooled weight ?
GO-480 weights are all over the place but 450-500 lbs.

I stopped in Gaithersburg MD one day and they had a tricycle gear Helio for sporting events camera work instead of the blimp. He said the nosewheel strut was the same as a Cessna 310.

There is another conventional gear Helio that has sat for many years in a hangar in Benton PA. Owner won't sell but does not fly it either.

I got the tail up once headed down the runway warming it up for an annual about 12 years ago. It wanted to fly but I decided maybe that was not a good idea not knowing much about it. I think that may have been the last time it was moving.
Real scavenger hunt finding components in the airframe. Standard parts in weird places. It had one 12V battery forward and another in the rear. Interesting spoiler/aileron combo.

Let’s drop in on them.

Yes, I watched the video. They have done a hell of job modeling the airplane and converting to match hole construction. That's not easy. I question some of their tooling but good fabricators can make good aircraft without good tooling. (BTW, bad fabricators can make bad aircraft with good tooling...something some OEM's don't seem to understand.)

I worked for a GA OEM for 17 years. It's so much harder than people realize. As much as they've done....they are about one quarter of the way there. People have done it before and will do it again. I hope they are one of them! I'm pulling for them.

Yes, I watched the video. They have done a hell of job modeling the airplane and converting to match hole construction. That's not easy. I question some of their tooling but good fabricators can make good aircraft without good tooling. (BTW, bad fabricators can make bad aircraft with good tooling...something some OEM's don't seem to understand.)

I worked for a GA OEM for 17 years. It's so much harder than people realize. As much as they've done....they are about one quarter of the way there. People have done it before and will do it again. I hope they are one of them! I'm pulling for them.

Did I understand them to say that they bought the Type Certificate? As I understand it, that means that they don’t have to prove the design meets the regulations. All they have to do (hah, “all”) is prove that they built it to the original type certificates drawings. Engine aside, that’s mostly about supply chain management and QA, isn’t it? I’m sure some of you understand the certification process?

If I was in their shoes, I’d install a 350 HP turbocharged Lycoming, and forego the advantages of a big, slow turning prop. Heresy for a TwinBo owner, but they’ll eat through all their money if they start with an uncertificated engine and try to get it certificated.

As I watched them discussing engines I kept wondering how an IO550b would work?

As I read Charlie saying he got the tail up before ‘chickening out’ I’m reminded of the sum total advice I got before settling into the left seat of P2-BOX the first time.

1/. When the tail comes up on takeoff she’s ready to fly…don’t keep her on the ground or she’ll start looking for new and exciting places to go, and take you there.

2/. Slats pop out at 39kts on approach.

3/. 8 cranks is half flaps…don’t even think about full flaps until you have 30-40hrs up in her.

On my first takeoff into a stiff wind I was off the ground before I had a chance to look at the ASI and understand the pitot tube was blocked - so when the slats popped out on approach with a bang I thought “oh 39kts”

Being young, dumb and full of you know what I tried a full flap landing with maybe 3hrs on type.