Glide Ratio / Sink Rate

[rotaxflyer]

I'm thinking of making a trip to Pelee island in Lake Erie in my BC12-D. This would include about 9 miles of open water. Anyone know how much altitude I would need to glide 4.5 miles? I gather that the best glide speed is 60 mph, but can't find any information as to what the actual sink rate would be.


Thanks,

Andy

[jgerard]

Re: Glide Ratio / Sink Rate

Sounds like an excuse to go do some test flying. Pick 2 ref point out on your map that are about 10 miles apart. Clime up to an altitude that you think might work, cross over the starting ref point and start your glide. Would be kinda fun to see how much a tail or cross wind would affect your gliding distance.

[fearofpavement]

Re: Glide Ratio / Sink Rate

I am not sure what the glide ratio is for a tcraft but a typical glide ratio for a single engine plane is in the 8 to 1 range. Assuming the tcraft is anything close to that you should have no problem reaching an altitude that will get you back to land. Sounds like a fun flight. Enjoy the view from way up there!

[dedrekon]

Re: Glide Ratio / Sink Rate

According to the late Wally Olson, the BC12D has a glide ratio of 11:1.
They're a lot of fun to fly along those mountain ridges and ride the thermals with the power idled back.
Anybody who's tried to land one a little fast on a warm day can attest to their propensity for flying and flying and flying.

V

[rotaxflyer]

Re: Glide Ratio / Sink Rate

11 to 1 eh? Well it sounds like 4000 feet would easily make it there or back with altitude to spare.

Thanks.

Anyone interested in Pelee island, try this link.

http://www.peleetourism.com/

[VictorBravo]

Re: Glide Ratio / Sink Rate

Glide ratio is affected by a lot of things. Headwinds, lift, sink, etc. I've personally been flying an airplane with a 40-1 + glide ratio and lost 2000 feet in about 30 seconds. If there's water involved, you're a fool to plan a flight over water at 11-1 glide ratio or whatever. Plan it at 5 to 1, but remember that you only need to be able to glide back to your starting point OR the island... so figure where your "point of no return" is somewhere in the middle of the over-water leg.

[dedrekon]

Re: Glide Ratio / Sink Rate

Hmmmm......safety is important, but I've flown the 26-ish miles from the Washington State mainland to Friday Harbor on San Juan Island many, many times and I never even considered climbing to 13,750 feet before I made the crossing.

To each her (or his) own, but if you want to USE your airplane, there will be plenty of times in your flying life when you won't have an acceptable landing spot to glide to, unless you confine your flying to the Kansas countryside.

I also make the flight up the Willamette River across downtown Portland on a regular basis.......there's about a 15 mile stretch there where the river is about the most inviting place to set her down if I lost power. The skyscrapers are a lot scarier prospect. I'm not saying fly recklessly or don't have a plan for when things go wrong, but you just have to accept some risk in flying (or driving, or walking)......and I believe the risk in this case is very small.

I'd be more concerned with the condition, maintenance and reliability of my airplane. If you doubt the plane, don't go. My opinion....4,000 feet will provide an excellent and reasonable margin. I'd go with you, but it's a 1,700 mile flight to Lake Erie from here. Sounds like a fun place to go!


V

[N96337]

Re: Glide Ratio / Sink Rate

I never get over 500' agl, because if something goes wrong, I don't want to be scared very long!!!
JH

[Forrest Barber]

Re: Glide Ratio / Sink Rate

Lake Michigan is always fun going to OSH the short cut way..... Pelee will be in sight the whole time, depends on winds. Use 7 to 1 or even 5 to 1 as Bill says.. this is for safety. I use 5000 ft for that crossing and feel real safe. That is 9 to 1 but I have done it a bit...higher if you ahve big headwind.

[dewhitaker]

Re: Glide Ratio / Sink Rate

Hi, I took an Operation Raincheck course years ago from Cleveland FSS, and at the time if memory serves correct, they suggested 8000 ft for the average light plane to cross Lake Erie. I believe they can do flight following. Might be worth it to give them a call. Enjoy your trip!

[Vasey fan]

Re: Glide Ratio / Sink Rate

I grew up & learned to fly out on the west end of Lake Superior, the engine still goes into "auto-rough" when I'm over water. I think that when I flew the Beastly Beercan to Kitty Hawk in '03, I was probably high enough for an Atlantic crossing.

[rotaxflyer]

Re: Glide Ratio / Sink Rate

Thanks everyone,

I'll let you know how it goes. If you don't hear back from me here, watch the news.

Andy

[taylorcraftbc65]

Re: Glide Ratio / Sink Rate

Andy,
If by Rotax flyer, you meen that you also fly ultralights, compared to a "flying lawnchair", you will think that you are in an ASH 25 glider.
I fly out from my place to Guadeloupe Peak under power, throttle back to idle, and play in the ridgelines. I don't have a vario, but it sure feels like about 2,000 feet per min. sometimes.
When I've had enough fun, I leave the power at idle, (more drag than engine off), and glide back to 2E5, (Dell City Mun.), touch, firewall the throttle, and fly home.
As to max. alt. gain, many times I have to bail out of the thermal, or bust class "A" airspace. Brie

[Len Petterson]

Re: Glide Ratio / Sink Rate

Let me know when you are going to the Pellee Isalnd and I come with you in KZU. (Gas money is in short supply But I realy would like to go)
Asumming a 9-1 glide ratio 4.5 miles / 9 = 1/2mile = 2700 ft so if we refuel in Chatam and climp to 4000 ft we make it. I know the old Canuck had a glideratio of 8.5 the T-craft is better so to play it safe 4 K should do.
I better check out the glide ratio.
But it is hot now= thin air= lower than normal L/D.
Point of No return has to calculated as well, depending on wind.
Len

[paulnuss]

Re: Glide Ratio / Sink Rate

Don't forget to adjust your "glide ratio" for winds; an extreme example, in a 60 mph headwind, at best glide of 60 mph, forward progress equals zero. Of course, the 60 mph headwind is unlikely, but a smaller one still can have a big effect on slow-gliding aircraft. Compute the "point of no return".

An old story: Back in the late 30's, my dad and a group of friends was standing around at the old Ebensburg, PA airport. It wasn't fit to fly, clouds and haze practically to the ground in a mountainous area. Then to their amazement, they hear the sound of an airplane engine. Out of the haze and murk, they see a small airplane landing and it taxies in. Of course, they all went over as the pilot shut down, asking how he got in, where he came from, etc. There were no radio beacons or navaids of any sort there and then. In any event, the pilot was a well-known aviator of the day; he had come from upstate Michigan, had been in the air several hours, and had flown over substantial portions of Great Lakes waters on his trip. He said that about halfway over Lake Erie, in and out of clouds, miles from shoreline, his engine started to run "auto-rough". He took out a small flask of whiskey he carried, took a snort, and the engine "smooothed right out"! A little later, engine sounded a bit rough again, and he took another snort. Again, the engine "smoothed right out"! He said, "You know, I had to drink most of the flask to keep that dang engine running!"