When did it happen?

[Apteryx]

Re: When did it happen?

In fact I don't know it. Is there a pic around...is it a pusher ?

Juke-
On site gallery starts HERE
Some of Neal (Wingman's) excellent work.
Note: Jim has past on, but the airplane (should) be flying/racing again, this year.

Paul

[First time Juke]

Re: When did it happen?

I see GB meant Pushy Cat. Okay !

[Apteryx]

Re: When did it happen?

Jim did qualify Pushy in '96 at 254.6..mph, with a good engine, it'd still be in the hunt, but you could noticably see him slow, when he went into a pylon, neck and neck with Jon Sharp, where the higher aspect wing had the advantage.
* Note* Jim raced the "Miller Special" (different airplane), earlier in his career, but not at those speeds.

Paul

[spacegrrrl]

Re: When did it happen?

Both Miller and Bohanan had issues with the racer besides aspect ratio. Their speeds were limited by prop interference at higher speeds. Bohannan did some testing with nitrous to figure out what the max speed was for his pusher and discovered at some point the prop just cavitated. In general you need 2 1/2 the chord of the nearest surface between the nearest surface and the prop to get ideal efficiency. Look at the DO335 and the Mixmaster and you see the props are further back from the horizontal stab for that reason.

Michele.

[Apteryx]

Re: When did it happen?

The only plus I see for a (rear engined) pusher, is from the crew standpoint, it leaves all the icky stuff, behind.
Much less cleaning

[SCEPTER]

Re: When did it happen?

The only plus I see for a (rear engined) pusher, is from the crew standpoint, it leaves all the icky stuff, behind.
Much less cleaning

NOW THAT'S FUNNY

[King]

Re: When did it happen?

The only plus I see for a (rear engined) pusher, is from the crew standpoint, it leaves all the icky stuff, behind.
Much less cleaning

Yeah, but you outa have to kneel behind one of these things, on a VERY cold morning AND with a BAD hang-over and try to turn that 50 inch prop against that high compression............and not slip forward into the prop when it starts.

That thing would spring to life and be at a couple thousand RPM instantly!!!

[Apteryx]

Re: When did it happen?

Yeah, but you outa have to kneel behind one of these things, on a VERY cold morning AND with a BAD hang-over and try to turn that 50 inch prop against that high compression............and not slip forward into the prop when it starts.

Scariest damn thing to watch, I got to a point where I'd turn away, figuring it was inevitable....
Always figured a big spring that you would wind backwards, and let fly, would have been safer

[Unregistered]

Re: When did it happen?

Always figured a big spring that you would wind backwards, and let fly, would have been safer

Yup, just like a big scaled up Cox .049...

Rob

[alaskaracer]

Re: When did it happen?

Like the way you used to start those little Cox model engines, with the spring deal.....

[King]

Re: When did it happen?

Scariest damn thing to watch, I got to a point where I'd turn away, figuring it was inevitable....
Always figured a big spring that you would wind backwards, and let fly, would have been safer

I loved every minute of it tho. Not many of us who have got to have that experience.

Stockton, CA was the year I got.....well.......um........had a little too much to drink at the hotel with the Blue Angels group on our floor.

Next morning.............uh well...........actually, when I got back to the room to get ready to go to the airport, the hang-over was already hitting me full tilt. We had an early morning race and it was pretty chilly and I was feeling pretty crappy.

I went over to Jim Bumford's pit ("Bummer's Bullet #55) and was given some Midol by the pretty crew. Midol (PMS formula) makes a hang-over go away pretty damn fast as far as I am concerned!

[Apteryx]

Re: When did it happen?

Stockton, CA was the year I got.....well.......um........had a little too much to drink at the hotel with the Blue Angels group on our floor.

I meet some of the Blues in the elevator, on the way out. They were wearing Thunderbird t-shirts, because "they didn't want to embarrass the Navy". Damn should've followed them, sounds like I missed some fun.

Paul

[King]

Re: When did it happen?

I meet some of the Blues in the elevator, on the way out. They were wearing Thunderbird t-shirts, because "they didn't want to embarrass the Navy". Damn should've followed them, sounds like I missed some fun.

Paul

I had been down in the hotel bar with Sandy Sanders and crew and when we closed down the bar I had every intention of going to my room and get some sleep. I took the elevator up and when the door opened, it was obvious there was a party happenening on our floor. I was walking down the hall and passing open rooms when all of a sudden a couple guys run out and pin me to the hallway wall and force feed me some "juice" through one of those water blasters.

Well the party started over for me. And they had a ton of young ladies with them!

[Blue Foam]

Re: When did it happen?

Both Miller and Bohanan had issues with the racer besides aspect ratio. Their speeds were limited by prop interference at higher speeds. Bohannan did some testing with nitrous to figure out what the max speed was for his pusher and discovered at some point the prop just cavitated. In general you need 2 1/2 the chord of the nearest surface between the nearest surface and the prop to get ideal efficiency. Look at the DO335 and the Mixmaster and you see the props are further back from the horizontal stab for that reason.

Michele.

There were also aircraft that violated the "2.5 chord rule" and had no issues. Specifically, this was thought to be a high risk area on the Lear Fan 2100 where the prop was located ~ one chord behind the horizontals and 1/2 chord behind the vertical. Everything was heavily instrumented by Hartzell to create test data for solving this issue through dampeners and blade design. They found the interference to be barely measureable.

The Cessna 336 and 337 had the prop disc located within 1/3 of a chord behind the wing and suffered no ill effects. Their was separation on the aft lower cowling which was reduced at one point by Riley with a longer spinner. The aircraft used metal props with no ill effects from the close wing wake.

The B-36 had almost the same geometry, yet suffered terible blade fatigue.

On the Rutan pushers and their copies, the prop flies in and out of massive separation due to the aft engine cowling and cooling outlets. This one area of separation is responsible for most of the performance shortfall of these designs for their HP/wetted area. It's a double hit: separation drag is bad, so is wrecking propulsion efficiency. Doing both is worse. The blade fatigue issue was so bad that all of these designs use ony composite or wood props; aluminum not allowed.

The dividing line seems to be the angle of the wake entering the prop disc and the amount of disturbed (separated) flow. Photographs of oil spatter on the B-36 show large areas of separated flow and the angle of the prop shafts were not parallel to the wing mean camber line. The 336/7 had the prop shaft closer to the extension of this camber line and the wing was far less cambered than the B-36. The Lear Fan had all airflow at the prop going virtually straight. Despite separation at the spinner, the propulsion efficiency was some of the highest ever achieved.

[First time Juke]

Re: When did it happen?

Look at the DO335 and the Mixmaster and you see the props are further back from the horizontal stab for that reason.

Here is an hangar talk link to the data of those two birds.

http://www.aafo.com/hangartalk/showthread.php?t=1679&highlight=do-335

Here for Dornier DO-335:

http://www.skylighters.org/encyclopedia/do335.html