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What 80 inches MP can do

This data from a ‘top secret’ test flight yesterday of a friends Glasair, a dedicated racer that will be at Reno next month. It runs a modified angle valve Lycoming at very high MP, with anti-detonation injection to hold temperatures within limits.

On the flight yesterday it climbed under power from 5,000 to 10,000 ft in four minutes while simultaneously accelerating from 200 to 400 mph GS. The whole flight was 17 minutes long. That takes quite a bit of power!

The idea is to run it as hard as it will go, climbing to stay under the speed limit until over 10,000 ft, and monitoring engine data the whole time. Then change some things and try it again.

Last Edited by Silvaire at 15 Aug 15:55

@Silvaire where do I get one? Take my money pls ;-)

LFHN - Bellegarde - Vouvray France

LFHNflightstudent wrote:

Take my money pls

… and the rest of your money will go to the engine overhaul fund, I somehow suspect that longevity was not one of the design goals for this engine configuration. The TBO is probably measured in races, not hours …

Biggin Hill

On a similar fun note – ISTR an article in a German mag decades ago titled “Frisierter Lycoming in flugfähigher Verpackung”, loosely translated as “Tuned Lycoming in flyable packaging”. It was about a Lycosaurus boosted well beyond spec in a custom built single seater airfame which could barely fit the pilot inside. The wingspan was subjectively as wide as the rudder was tall. The highlight of the flight was overtaking a King Air with a (presumably) very puzzled crew wondering what that gnat of an aircraft zooming by was…

Biggin Hill

It goes long enough between overhauls to be ferried from place to place at somewhat reduced boost/power etc. plus operation at something like 800 HP for tens of hours. That depends on holding cylinder temperatures down and thereby material strength up. The bottom end, crankshaft, bearings, oil system etc seem to take it better than you might imagine in the short term and fatigue becomes the issue. The cylinders come off after a major event and the bottom end comes apart occasionally, with crankshaft replaced. The engine was originally a Piper Malibu Lycoming (350 HP) so lightly used engines can be found from which to scavenge parts. No engines have come apart ‘on their own’ yet over the last several years.

The CHT at the top of the flight on Saturday was 220 C, so a bit more ADI (anti detonation injection) is needed. It cannot be run at high power without ADI.

All the work on everything including design is done hands on by the partnership of two guys that owns the plane. It was built from an insurance company totaled Glasair III, and apparently the basic airframe design is good for the TAS seen at e.g. Reno, 435 mph is the goal. It’s not the kind of plane that they fly for fun, flaps have been removed etc and it takes a very disciplined approach (literally and figuratively) – a steep bank 360 is necessary to lose speed and then to keep the runway in sight, all the way from overhead to short final. It is however great fun to watch and play helper on a Saturday.

On one recent flight ATC was moving people to the parallel runway before the plane had even called them up to request landing clearance, not many planes including jets going that fast 10 miles out, obviously inbound and they can see the tail number from ADS-B.

Last Edited by Silvaire at 16 Aug 14:31

Silvaire wrote:

What 80 inches MP can do

On a normally aspirated engine? Hmm, let’s see…we need a booom smiley here!

In fact, I could give it a try and move that manual wastegate lever full forward on ground. In terms of Euros per hour, if it runs only seconds like this, would be quite an interesting number. Additionally, I would have to go through the streets and collect money for my engine rebuild then – so I won’t follow your lead and try what 80 inches could do

Other than that, sounds like a lot of fun!


Silvaire wrote:

tens of hours

I rest my case

I suspect that the engine is taken apart and reassembled frequently, and each time it becomes a little bit more powerful.

Did they reinforce the Glasair? With plastic aircraft, sometime people just add more layers, but the Glasair wings are metal, I believe?

Biggin Hill

Not to disparage the project, merely for comparison:
TIO-540 in question: 270 kg + anti-detonation injection system, ~800 hp, ~100 hours TBO (?)
PT6A-140: 175 kg, ~900 hp, 4000 hours TBO

Last Edited by Ultranomad at 16 Aug 14:27
LKBU (near Prague), Czech Republic

Ultranomad wrote:

4000 hours TBO

I protest! Under abusive conditions, presumably like this one the PT6 can also be destroyed in 100 hours


Another guy at my base just switched from a Lancair to an L-39 because he decided it’s more fun if race plane maintenance consists of cleaning the windshield and not much else. Also the fuel providers are very nice to you, and having stayed single until his 60s and meanwhile having spent his airline captain salary over the years on buying apartment buildings, he can afford the gas

The piston engine guys do it as much as anything for the challenge, it’s interesting to make a widely seen homebuilt design perform like a stock P-51.

Last Edited by Silvaire at 16 Aug 14:58
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