Hummel is flying an Ultracruiser with a Predator

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karmarepair

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The new owners of Hummel Aviation have been hinting at other engine option, and at the Gathering last weekend, they showed their hand.

Predator with billet rods, hotter cam, lightweight flywheel, charging coils deleted, belt psru, heads shaved to raise the compression, governor removed. The demon tweaks are PROBABLY from Performance 670, such as Product Description and Product Description and Product Description

Screen shot from

Predator_UC.png

More details in this video

There is nothing yet on the HOME | Hummel Aircraft web site yet. I'm curious where they sourced the PSRU.
 

karmarepair

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Were you there? It was very exciting to see!
I was NOT. Friends were.

And one of them relayed that the PSRU is the creation of Matt, the new owner of Hummel Aviation. It's a pretty low ratio, 1.7 to 1. And the three bladed prop is needed to get enough blade area to absorb the horsepower while keeping sufficient prop clearance. Dennis Brooks was concerned about the oil pressure being only 25 psi, but apparently that's what they run - the oil galleries on these V-twins are very short and straightforward compared to a VW.

There is another toiler in this field, in the Facebook Hummel group, Lewis Clark out of Wisconsin. His engine is more highly modified than Matt's, higher lift rockers, dual carbs, crank trigger ignition. About $2000 in performance parts on a $900 engine. PSRU will likely be another grand. He hasn't flown yet.
 

Flyguyeddy

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I was told the weight was slightly less than the 1/2 vw but with a starter. Ot was quite the sight to behold. I heard the same complaints from dennis. Maybe relief valve is not seating all the way?
 

Vigilant1

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The banter in the bottom video was interesting, especially the idea that it requires a dynamometer to know the output of an airplane engine.
Any reports of performance and CHT of the Predator 670 in flight?
 

challenger_II

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I have found that a propeller makes a very good dyno: match the performance One is getting from One's test set-up, and compare to a known, and well documented, engine/redrive/propeller combination.
I WOULD say that using a dyno to get the power specs is much more reliable than using some of the engine power calculators that are found on the Internet.

At the end of the day, HP is just a number: Thrust is what flies the plane. I'd be interested to know what the prop dimensions are, on their rig, and what engine/propeller rpm they are turning. I haven't seen whether they are using a cog belt, or a micro-groove V-belt in their reduction.
 

Flyguyeddy

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They had two of these at oshkosh. Im assuming the other one is the previously mentioned engine being built by a third party. The carburetor is now mounted low for gravity feed purposes. Looks very interesting.
 

Bigshu

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They had two of these at oshkosh. Im assuming the other one is the previously mentioned engine being built by a third party. The carburetor is now mounted low for gravity feed purposes. Looks very interesting.
One of the engines belongs to the guy who had the bare metal UC with the for sale by owner sign. I'm pretty pumped about the engine after talking to Matt. I've got pics of the engines and their feature list on another thread (Oshkosh 2022?).
 
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