Bob Axsom said:
At airports in densely populated areas I personally would turn back even if there was little hope for my personal survival.
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I flew R/C's for many years, and quite a few with heavy wing loadings and low glide ratios. And several of our R/C "airports" didn't have bare enough surroundings for successful off field landings.

Between a number of unsuccesful return to the runway scenarios by myself, as well as witnessing many others, I've seen numerous R/C airplanes just drop a wing & spin in. At that point, there is no control whatsoever, and whatever is underneath the unintentional crash spot, is forever underneath.

Because I've seen quite a few results, of return to the runway stall/ spin "crashes", that happily envolved non-piloted airplanes, I've resolved to never try it, unless I know for sure that I have the required altitude, through prior testing.

A few years back, I seen a Cessna 152 perched in a tree against a building in a very crowded shopping center parking lot. The student pilot had run out of fuel, and having no good options, went for the tree. The pilot survived with only a few scratches, and even the airplane was not too beat up. IMO, this is my option, which is to stall at the last second into a tree if needed.

Just last winter, a Cessna 310 performed a last second stall into a 45 degree mountain upslope within sight of my home. Again, both the pilot & passenger got out of that one with a few minor scratches. I think the last second stall to dissapate as much forward speed as possible, is preferrable to an un-controlled last second spin possibility; even if it's into something that the pilot might not survive, but hopefully avoiding people in the path.

L.Adamson
 
Please

Are you telling me you can't stand it on it's wing and hard slip around without stalling? I used to do it every morning flying to work for over 15 years allowing 1,000 ft AGL for a 270 degree turn from midfield crossing to the runway threshhold and I do it many times now in the RV-6A - the sink rate is greater and you have to lead the rollout more but it does fly like an airplane. Hope you find a tree to stall into if your engine dies but if I'm by an airport that's my first choice. It bothers me to tell pilots that it is sure death to change the direction of flight if the engine stops. I can just see them sitting there with their pucker factor going up, frozen at the controls thinking I can't turn or I will die as they glide into a home off the end of the airport. Do something even if it is stall into a tree top.

Bob Axsom
 
I do slips around turns all the time in the Citabria too. Very safe, and very fun. He was talking about skidding it around turn. This is the *classic* spin it into the ground on base->final maneuver.
 
Bob Axsom said:
Are you telling me you can't stand it on it's wing and hard slip around without stalling? Bob Axsom
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Living next to an un-towered airport, and driving home one day, I seen a Stearman fly downwind, then do a 180 litterly standing on it's "wings", in the width of the four lane highway next to the runway, and just a few hundred feet beneath. Quite impressive! Too bad all airplanes can't do that! But then a Stearman isn't exactly a low drag speedy aircraft either.

edit:

Back to R/C planes again. While some will easily make quick reversals in the flight path, with no problem at all; I remember two incidents of accelerated stall/ spins. One was a pullout of a too low loop with a large quarter scale Cap 21. It pulled out okay to level flight, but began a horizontal spin within the next second. In the second "crash", I made a tight crosswind to downward turn after takeoff. Again, the R/C craft made the turn, but began a spin within a second of the completed 180. Most likely wasn't even using rudder at the time, for any cross-control probems. I figure "full size" can have the same results, good or bad, depending on type of airplane, airspeed, etc.
 
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Yes I agree

jcoloccia said:
I do slips around turns all the time in the Citabria too. Very safe, and very fun. He was talking about skidding it around turn. This is the *classic* spin it into the ground on base->final maneuver.
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Yeah, I caught that also but I don't think the fellow meant to kick it around without an appropriate bank but if one is there trying to minimize altitude loss, a low slow flat turn with a stalling inside wing is a scary probability in execution.

Bob Axsom
 
Bob Axsom said:
Are you telling me you can't stand it on it's wing and hard slip around without stalling? I used to do it every morning flying to work for over 15 years allowing 1,000 ft AGL for a 270 degree turn from midfield crossing to the runway threshhold and I do it many times now in the RV-6A - the sink rate is greater and you have to lead the rollout more but it does fly like an airplane. Hope you find a tree to stall into if your engine dies but if I'm by an airport that's my first choice. It bothers me to tell pilots that it is sure death to change the direction of flight if the engine stops. I can just see them sitting there with their pucker factor going up, frozen at the controls thinking I can't turn or I will die as they glide into a home off the end of the airport. Do something even if it is stall into a tree top.

Bob Axsom
Click to expand...

I simply said think about this before you do it. Obviously if you have enough altitude, many more options are open. If you are thinking about this maneuver, best to practice it and see how much altitude you need, then add another 20-25% for a no power situation. Idle thrust on an RV makes a big difference in glide ratio.

The same other considerations still apply about high groundspeed on touchdown and possibly having another airplane facing you. Naturally circumstances and terrain figure into your decision. The fellow I mentioned who was killed recently was a highly experienced ex Vietnam vet, CFI etc., exceptional pilot. Many of us are not in that league. He just did not have enough altitude to recover controlled flight after this maneuver.

To ignore how many people have been killed attempting this over the last 100 years may make you another statistic to be added to this cause. Please carefully consider what you will do in this situation. Practicing this at altitude may allow you to decide whether it is an option for you and what your go- no/go altitude should be.
 
I absolutely agree with that

You are right on the money in my book. Try it at altitude and add a pad to establish the turn around floor for you and your airplane. If the engine quits below that altitude you still have to improvise - quickly - to get your best shot at survival. I flew 4 Young Eagles this afternoon and on one of my climbouts at about 300ft AGL, I thought about the engine failure in a more than abstract setting. I thought my if this engine quit right now it would really be tough to pull off a clean recovery. In that particular situation I would have shoved the nose over hard and tried to land on the remaining runway (probably 3,000ft remaining). I do not believe it is a trivial situation nor is it one that has a single solution for every situation. By all means practice the 180 turn at altitude to get an idea of altitude loss and add 25% as your turn around floor and add it to your options. As I said before 700 ft is my "no-sweat" turn around floor.

Bob Axsom
 
jonbakerok said:
In my RV6A with C/S prop, it's easy to judge potential landing sites. Just look out the side at the point on the ground just covered by the wing. Imagine a circle that distance around you on the ground. Anything within that circle is reachable if you do everything just right.
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I have been attempting to come up with a practical method of judging how far I could glide if the engine failed in my 9A. From earlier tests I know that my best glide with a dead engine is at about 80 kts with the prop full coarse and the throttle full in. This gives a glide ratio of between 1:10 to 1:11. Even though Jon has a 6A and I have a 9A I have also found that looking out over the wing tip when flying straight and level gives a good approximation of my glide ratio. Any area of land that I can see over the top of the wing tip is beyond my glide ratio, any land below the wing tip is within the glide ratio and should be within gliding distance. I have put this to the test by lining up the runway with the wing tip from a few miles out and then flying a simulated engine failure glide and have found I can just make the runway. To explain, I have found that in my plane I can simulate a dead engine glide with the engine firing, the throttle at idle power and the prop at full coarse then in one full turn. Obviously headwinds and areas of sinking air will effect the glide ratio but the wing tip method seems give a good indication if a quickly selected forced landing area is doable.
The next task is to determine reference points, (say on the leading and trailing edges of the wing) that would give a similar visual approximation of the possible glide with a dead engine and the prop in full fine due to a loss of oil pressure caused by no oil or some mechanical failure.
The wing tip seems to be the visual reference for my aircraft, other aircraft may differ.

Fin
9A
0-320, Hartzell C/S prop.
 
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Finley Atherton said:
The next task is to determine reference points, (say on the leading and trailing edges of the wing) that would give a similar visual approximation of the possible glide with a dead engine and the prop in full fine due to a loss of oil pressure caused by no oil or some mechanical failure.
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This might be a good time to pass on the standard technique for judging glide in unpowered paragliders (which have an 8 or 9 to 1 glide - i.e. crummy).

After you've turned towards your 'field' - pick out an object over the cowl and watch it for a second. If the object is "going up" on the windscreen you won't make it - you need to land someplace closer. If it is "going down" you will be long - plan on ditching altitude once you get closer.

I've tested this rule many times in my RV and with a little bit of practice it becomes very obvious & handy (though if the RV is working I can cheat and add power).
 
Best Glide

FWIW, to determine best glide in my old Pitts, the theory was to drop a brick out of the canopy and follow it. The RV will do better I suspect.:D

I have done the 180 turn back in a RV-4 from 300'. This is something that must be practiced at altitude until you are comfortable turning past 60 deg of bank, and putting the nose way down even though you are close to the ground. It's also imperative you keep the 'ball in the centre' to avoid an inadvertent snap roll. Unusual attitude training will help here. Having said all of this, statistically, it's safer to land straight ahead.
 
My 9A

Here is some data I took a while back. I notice a lot of words about how fast these airplane sink, but I think that is with constant speed props verses my fixed pitch. I think the difference is dramatic
glide.jpg


By the way, I'm not buying the argument that an airplane will glide just as far at heavier weights. I need to figure out how to set up the problem, but I think its a simple drag issue associated with the higher airspeed required at heavier weights.
 
Steve Brown said:
By the way, I'm not buying the argument that an airplane will glide just as far at heavier weights. I need to figure out how to set up the problem, but I think its a simple drag issue associated with the higher airspeed required at heavier weights.
Click to expand...
There is an old VHS tape I have from ABCs Wide World of Flying where this is demonstrated. It proves that the glide is the same at heavier weights but with a higher glide speed. They also demonstrate the glide with stopped prop, and fine vs. coarse pitch. These demonstrations were done in a C-182.
 
This wouldn't be the first time...

Mel said:
There is an old VHS tape I have from ABCs Wide World of Flying where this is demonstrated. It proves that the glide is the same at heavier weights but with a higher glide speed. They also demonstrate the glide with stopped prop, and fine vs. coarse pitch. These demonstrations were done in a C-182.
Click to expand...

.....that my instincts were wrong. I'll still need to crunch some numbers to get my intuition realigned with reality.


By the way, the glide distance on my graph was during the 1000 foot decent I used for my measurements. I stabilized airspeed before starting each test.
 
Steve Brown said:
... I stabilized airspeed before starting each test.
Click to expand...
If you measure glide angle at different weights, but at the same airspeed, the angle will decrease. The best achievable glide angle is the same at different weights, but the speed to get that best angle varies.

This is glider 101 and well covered in any basic glider text. There is an overview on the web http://home.att.net/~jdburch/polar.htm

The part about different weights is right at the end.
 
Those of use with handheld Garmin GPS can use the glide ratio feature to practice. Open two windows: current glide ratios and glide ratio to target (target has to be an airport entered in data base), go to altitude and practice. It should give you a ballpark feel for your aircraft.For my 6A 85 to 90mph for around 11:1 with engine idle (light load) less without power. Glider training will help.
 
Hi Steve,

Interesting information in post #67. Your glide figures look a bit different (and better) than mine. Were your tests done at idle power or with a "dead" engine? I presume the prop was full coarse?
Thanks,

Fin 9A
 
This is important

agough277 said:
Those of use with handheld Garmin GPS can use the glide ratio feature to practice. Open two windows: current glide ratio and glide ratio to target (target has to be an airport entered in data base), go to altitude and practice. It should give you a ballpark feel for your aircraft.For my 6A 85 to 90mph for around 11:1 with engine idle (light load) less without power. Glider training will help.
Click to expand...

Agough beat me to it but allow me to add emphasis. If you are in that situation for real then you are dealing with unknown wind. If you have those two data windows on one of your panels, ready to go, then you will get critical information that applies to the instant circumstance. I think this is the best you can do and it could be a lifesaver. Do keep in mind if you have much altitude that the headwind can increase with altitude loss, although that's less likely.

As to what speed to use, if you know the best L/D speed, that's your starting point and you already know to vary it with upwind or downwind. To find your best L/D speed, just use the glide angle as reported by the Garmin and it won't matter if it's idle power or partial power so long as you are consistent, then the best speed will be obvious and for a given weight, speed will be the same. That's IAS, of course. You'll want to do this ahead of time!;)
 
Test conditions

Finley Atherton said:
Hi Steve,

Interesting information in post #67. Your glide figures look a bit different (and better) than mine. Were your tests done at idle power or with a "dead" engine? I presume the prop was full coarse?
Thanks,

Fin 9A
Click to expand...

I've got a fixed pitch Catto and the engine was at idol. My excuse for not pulling the mixture was that my wife was in the airplane helping me take data.

The truth is that right now I can't seem to gather the snickers to kill the motor deliberately in flight. Maybe if I could find a an airport with long runways in an unpopulated area with friendly terrain I might try it.

My RV training was in an RV10 with CS prop. That thing would come down like a rock if you wanted it to. My first few flights in my airplane I was stunned at how much it wanted to glide. No resemblance to the FP 172s, 152s, Warrior's, etc, that I've flown in the past. For one the airframe drag is much lower, but also they all had props pitched for 100-to-120 kts, not 164 kts like a 9A.

If I pull the power to idol at 130-to-140 kias and maintain that airspeed I can get some pretty decent compression braking, resulting in high sink rates. At low speeds, particularly at the lower end of my graph, I doubt there would be much difference between engine idled or shut down.

I am planning to do some more glide testing. In CA its hard to be very far from mountains and depending on temperature and wind speed/direction, I think very difficult to get into air that is not either rising or falling. The day of those glide tests my location and conditions were far from ideal.
 
Now that I've reread this thread end to end, I've learned a lot. So...here's my plan. In the future I plan to only takeoff downwind. That way, if I lose an engine right after takeoff, I can do a quick turn and land right back at my takeoff airport, into the wind! Or, in the alternative, I will try to find an airport that has another airport directly in line with it but only one mile away. That way, if I lose and engine...

Juuuuust kidding of course, just tired of working on mine today. In actuality, I'm not flying at all, darn it. One of these days!

Regards,


Lee...
 
Pierre:
Being a poor GPS owner my Garmin GPS Pilot III has this feature but not on all pages. Try different pages and scroll through the windows options. Remember the target has to be in the data base with a known altitude.
 
Flaps instead of red knob...?

Hi.

To get practice in simulated emergency landings with a realistic sinkrate, maybe one could extend some flaps to simulate the added drag for an engine out? (then the engine could be left running at idle)

When we where practicing simulated engine out pattern with the F-16, we extended the speedbrake for 1 second. This added drag would "zero out" the effect of an engine at idle and not at windmilling.


Since best glide speed is below max flaps speed, maybe 10-15* of flaps would do the trick?
I guess 1100-1200' VVI is realistic with a windmilling engine and the the blue knob pulled?
 
Pierre:

Go to the "Position Data" page on your Garmin x96 (the page with lots of boxes with data). Hit menu, select "change data fields" and "enter". Highlight the databox on the screen you want to change, and press enter again. Scroll through the list of available parameters to highlight "glide ratio" and enter. Repeat process to add Glide Ratio to Target.

Alternatively, I believe you can also display this info on the map page if you have set up the page layout to include displaying a few parameters.

Garmin doesnt list all the possible parameters it can display in the manual, so it pays to dig through the list to see what is possible.

regards

erich
 
Steve Brown said:
I've got a fixed pitch Catto and the engine was at idol. My excuse for not pulling the mixture was that my wife was in the airplane helping me take data.

The truth is that right now I can't seem to gather the snickers to kill the motor deliberately in flight. Maybe if I could find a an airport with long runways in an unpopulated area with friendly terrain I might try it.

My RV training was in an RV10 with CS prop. That thing would come down like a rock if you wanted it to. My first few flights in my airplane I was stunned at how much it wanted to glide. No resemblance to the FP 172s, 152s, Warrior's, etc, that I've flown in the past. For one the airframe drag is much lower, but also they all had props pitched for 100-to-120 kts, not 164 kts like a 9A.

If I pull the power to idol at 130-to-140 kias and maintain that airspeed I can get some pretty decent compression braking, resulting in high sink rates. At low speeds, particularly at the lower end of my graph, I doubt there would be much difference between engine idled or shut down.

I am planning to do some more glide testing. In CA its hard to be very far from mountains and depending on temperature and wind speed/direction, I think very difficult to get into air that is not either rising or falling. The day of those glide tests my location and conditions were far from ideal.
Click to expand...

Thanks Steve. Having the engine at idle power would account for your better glide figures. I agree it is difficult to get good conditions for glide testing. Even in what appears to be smooth air it can sometimes be hard to accurately maintain a set airspeed and I find that often the sink rate will vary even with the airspeed pegged. I am not advocating that you do the tests with a dead engine but it really is no big deal killing the engine in flight. I was a bit nervous at first, but if you are at idle power you would be hard pressed to notice much difference when you pull the mixture back. Naturally you would want plenty of height and be within easy gliding distance from a runway. I like to get the CHTs in the low three hundreds before in-flight shut down to minimize shock cooling. I have also done glide tests with the prop stopped and I will admit that does make me a bit anxious. :eek:

Fin
9A
 
ao.frog said:
Hi.

To get practice in simulated emergency landings with a realistic sinkrate, maybe one could extend some flaps to simulate the added drag for an engine out? (then the engine could be left running at idle)

When we where practicing simulated engine out pattern with the F-16, we extended the speedbrake for 1 second. This added drag would "zero out" the effect of an engine at idle and not at windmilling.


Since best glide speed is below max flaps speed, maybe 10-15* of flaps would do the trick?
I guess 1100-1200' VVI is realistic with a windmilling engine and the the blue knob pulled?
Click to expand...

Should work. Certainly should be more realistic. I suppose ideally you would need to do actual engine out glides to find out the best glide speed, note the sink rate and then fly at that speed at idle power and adjust the flaps to get the same sink rate?? Flaps may change the attitude of the plane so the view out the window may look a little different to an engine out, no flap glide? I don?t know about other RVs but my best glide speed is actually slightly above the max flap speed. I find that I can closely simulate the dead engine glide with the engine at idle power and the prop full coarse then in one turn.

Fin
9A
 
Best Glide Speed Independent of Thrust

Finley Atherton said:
... I suppose ideally you would need to do actual engine out glides to find out the best glide speed, ...

Fin
9A
Click to expand...

For safety's sake I want to say this again, a little louder:

You can find your best glide speed at any partial power, for a given weight. You don't have to turn off the engine.

Yes, you'd have to turn off the engine to know the best glide ratio, but that's not the same thing and it's only theoretical because of wind, anyhow. In a real emergency you have to vary the speed depending on wind and actual glide performance will thus vary even more.

You can find best glide speed with the Garmin X96 "glide ratio" data field. You want to find the speed at which a given power setting gets the best (greatest) glide ratio. That speed will be the same at any power setting below level flight although the ratio will be higher with more power. I found that a partial power setting that gave about 33:1 glide ratio was easiest to work with, but that's an individual preference.
 
Good idea!

Hi Finley.

Your idea is much better than mine: to pull out the blue knob and then in again until the prop gives the required drag to outweigh the idling engine. Superb!

I'll try that on the next flight for sure and see how it works.

Anyone else have tried this?

PS: enjoy summer down there! Up here winter is fast approaching... yuk!
 
hevansrv7a said:

For safety's sake I want to say this again, a little louder:

You can find your best glide speed at any partial power, for a given weight. You don't have to turn off the engine.

Yes, you'd have to turn off the engine to know the best glide ratio, but that's not the same thing and it's only theoretical because of wind, anyhow. In a real emergency you have to vary the speed depending on wind and actual glide performance will thus vary even more.

You can find best glide speed with the Garmin X96 "glide ratio" data field. You want to find the speed at which a given power setting gets the best (greatest) glide ratio. That speed will be the same at any power setting below level flight although the ratio will be higher with more power. I found that a partial power setting that gave about 33:1 glide ratio was easiest to work with, but that's an individual preference.
Click to expand...

Conceded, your method would be a safer way of determining best glide speed. However I still maintain that it is helpful knowing the real sink rate at that best glide speed with the engine dead.
I may just be misinterpreting, but I don’t really understand the statement, “In a real emergency you have to vary the speed depending on wind.....” I would be grateful if you could explain this in more detail.
Thanks
Fin 9A
Edit. I think the light bulb just went on. Do you mean the speed across the ground rather than IAS??
 
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I think I can answer that - no, he means IAS. Best glide speed depends on wind conditions. It will be higher with a head wind, lower with a tail wind. Best option is to have the GPS set up to display glide ratio and then simply fly at the speed at which glide ratio is maximized.

erich
 
Do what you gotta do, but..

Finley Atherton said:
Conceded, your method would be a safer way of determining best glide speed. However I still maintain that it is helpful knowing the real sink rate at that best glide speed with the engine dead.
I may just be misinterpreting, but I don’t really understand the statement, “In a real emergency you have to vary the speed depending on wind.....” I would be grateful if you could explain this in more detail.
Thanks
Fin 9A
Edit. I think the light bulb just went on. Do you mean the speed across the ground rather than IAS??
Click to expand...

Fin, I hope this will help clarify.

No, I meant airspeed as was stated by Erich above.

I don't see the value - beyond curiosity - of knowing the sink rate. It's all about getting to the target while still in the air. Sink rate is relevant only when part of a calculation that includes forward speed over the ground. Minimum sink (in still air) is not best glide, either. Angle over the ground is what Garmin reports and that's what counts.

Glider pilots (I am not one) have many rules of thumb for varying speed with wind and they are easily Googled. Proof of the concept: if my best L/D is at 96 kts and I have a 96 kt headwind, I won't make forward progress. Extrapolate from there. Faster into a headwind, slower with a tail wind. With a strong tailwind, I'd go for minimum sink speed which is 76%, roughly, of best glide speed. I would not go any slower.
 
Best Glide In Wind

Not content with rules of thumb, I re-used a spreadsheet that already had drag polar information on it. I wanted to see what the best speed would be while taking into account the changes in L/D performance attributable to the speed change - independent of wind. I got a surprise.

If I get enough requests/demands I'll pretty it up and post it but for now, here is a summary. I used 96 kts/110.5 mph as my best L/D speed which is almost exactly what CAFE said for the 6A. I used 1500 pounds for weight. I ran a matrix which included going from tailwinds of up to 55 mph to headwinds of up to 55 mph, starting with 10 and using ten mph increments except for the big ends. I calculated the effective glide ratio after considering wind for speeds above and below best L/D. My theoretical best L/D for this was 10.34. Yours will not be far from that if you have an RV.

For winds of as much as 20 mph, the best speed adjustment was much smaller than I expected: 106 and 116 mph were the best speeds for 20 mph winds on the nose or tail. For 30 it's 104 and 119. For 55 mph it's 100 and 132. Since my least-sink speed is by definition 73 kts/84 mph, my earlier statement about using the least-sink speed with a strong tailwind is proven a bad idea.

I've not compared these findings to the rules-of-thumb glider pilots use, but this is based, I believe, on good data and good math.

Use it and be safe.
 
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