RV-7 Egg H-6

Yukon · #1 06-22-2007, 09:58 PM

Does this look like 200 HP to you?

http://www.youtube.com/watch?v=Et4ivK7le5I

cawmd82 · #2 06-22-2007, 10:23 PM

How hot was it? Maybe he wanted to get a good look at the end of the field? Maybe Jan is paying him as a nearly worst case scenario test pilot? Loaded to 3000 lbs???

Mike S · #3 06-22-2007, 11:37 PM

You will note that the pic zoomed in twice------------this causes the apparent distances to be distorted, making the trees at the end look much closer to the departing plane than they actually were.

Dont trust all you see------------

Mike

pierre smith · #4 06-23-2007, 06:18 AM

We have a friend with the 4 cyl Sube in his clean -7 and it uses about 1000 feet to get off.....terribly slow. From his fuel burn at 7 GPH, it has been figured that he might make 135 HP. The 200 HP figure is, methinks, a bit optimistic since I've seen many 180 and 200 Lycs take off from grass with two aboard, much, much sooner. The Sube installations are also heavier by far. Oh well, to each his own.

Pierre

captainron · #5 06-23-2007, 06:53 AM

http://www.youtube.com/watch?v=oM8ID...elated&search=
I watched the take-off run (inside) and from the start of the T/O run to approx. 500' AGL looked like about 50-55 seconds. Seemed pretty anemic to me. Don't know what all the other conditions were, though.

rv6ejguy · #6 06-23-2007, 08:58 AM

Was this the four or a six?

Yukon · #7 06-23-2007, 09:54 AM

Both were H-6.

cjensen · #8 06-23-2007, 10:03 AM

Jeez John, haven't we been thru this on RB already?

I have no doubts that that airplane is NOT making 200hp. He has the 1.82 redrive, and at 2700 prop rpm, it's making about 175hp or so.

So, to answer your question...no, it does not look like 200hp.

200hp comes in at around 5400rpm. With the 2.02 drive, you get 200hp at 2700 prop rpm. That is the reason that this particular owner has ordered the new drive.

Quote:

captainron http://www.youtube.com/watch?v=oM8I...related&search=
I watched the take-off run (inside) and from the start of the T/O run to approx. 500' AGL looked like about 50-55 seconds. Seemed pretty anemic to me. Don't know what all the other conditions were, though.

Not sure at all how you can tell it seemed anemic from the video.

Idicated climb rate was 1780fpm, and it was an intersection departure. That hanger that I panned over to after we were in the air is 1000' from the interesection we departed from. Probably 5 or 600 feet roll I would estimate.

captainron · #9 06-23-2007, 10:32 AM

Quote:

Originally Posted by cjensen

Not sure at all how you can tell it seemed anemic from the video.

Idicated climb rate was 1780fpm, and it was an intersection departure. That hanger that I panned over to after we were in the air is 1000' from the interesection we departed from. Probably 5 or 600 feet roll I would estimate.

I noticed your altimeter before take-off indicated 900'MSL. Near the end of the video, and about 50-55 seconds after the engine went to full power, the altimeter was indicating 1400'MSL, or a 500" gain during that period. I assume you weren't deliberately climbing "flat" because of CHT issues with your water-cooled engine.

flyeyes · #10 06-23-2007, 11:21 AM

Quote:

Originally Posted by captainron

I noticed your altimeter before take-off indicated 900'MSL. Near the end of the video, and about 50-55 seconds after the engine went to full power, the altimeter was indicating 1400'MSL, or a 500" gain during that period. I assume you weren't deliberately climbing "flat" because of CHT issues with your water-cooled engine.

I time it at about 42 seconds from rotation to 600 AGL at the end of the video.

That's about 850 fpm, which is well below Van's spec for a 160 hp RV.

If the engine is making 175 horsepower at 2700 prop RPM (which it very well may be) then there are significant losses elsewhere in the system. I don't know if it's in the redrive, prop efficiency, or what, but it doesn't perform like a "similarly powered" Lycoming equipped airplane.

I really like the idea of auto-engine conversions. I like the water cooling, smoothness, and potential economies of scale, but I haven't seen one that performs as well yet wasn't either very labor intensive (Tracy Crook) or expensive (Mistral)

As another data point, I found this short clip of a pattern trip in my RV-8. It isn't great video, and I touch down too fast (and skip a few times), but you can see I rotate at about 19-20 seconds in the video, and pass through 600 AGL about 18 seconds later, which is very close to Van' spec for a 200 hp RV-8.

To my best recollection, I was about 250# under gross weight, and temp was about 30 degrees F over standard in the video