# Hummel is flying an Ultracruiser with a Predator

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#### karmarepair

##### Well-Known Member
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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

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.

#### Flyguyeddy

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Were you there? It was very exciting to see!

#### 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.

#### ScaleBirdsScott

##### Well-Known Member
Neat little setup. What's the weight on one of those at the end of the day?

#### TFF

##### Well-Known Member
It would be nice to see it run.

#### 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?

#### Flyguyeddy

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It would be nice to see it run.
There is a video on youtube. Lemme find it

#### Turd Ferguson

##### Well-Known Member
The engine is on the Hummel Facebook group. Basic engine is 78 lbs. That's with no intake, exhaust but it does include the re-drive which is apparently made in India. A company called ACEAVIATION makes re-drives for all kinds of V-twins.

#### Flyguyeddy

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The engine is on the Hummel Facebook group. Basic engine is 78 lbs. That's with no intake, exhaust but it does include the re-drive which is apparently made in India. A company called ACEAVIATION makes re-drives for all kinds of V-twins.
The hummel redrive is made by matt, the current hummel owner. NOT ACE

#### Flyguyeddy

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Karmarepair, im actually in the bottom video of your OP

#### 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

##### Well-Known Member
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.

#### galapoola

##### Well-Known Member
Looks like the weight they save on the engine package frees up a tricycle gear and still make 254.

#### Flyguyeddy

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Looks like the weight they save on the engine package frees up a tricycle gear and still make 254.
Yup and just barely too

#### 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?).

#### Flyguyeddy

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That ultracruiser had some issues that the untrained eye might not catch

#### Bigshu

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That ultracruiser had some issues that the untrained eye might not catch
Yeah, when it comes to something like an UL, its buyer beware on the used ones. Hummel seems to be supportive of their builders though, so it wouldn't make sense for them to have unsafe builds in their booth.

#### Flyguyeddy

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Yeah, when it comes to something like an UL, its buyer beware on the used ones. Hummel seems to be supportive of their builders though, so it wouldn't make sense for them to have unsafe builds in their booth.
Im sure its probably fine, it just has some ugly spots.