Gear Retraction on Take Off

[billsheila]

Essentially I treat the Skymaster like a single engine plane on take off, once I'm high enough for no landing on the runway the gear comes up.[/quote]

I must be mis-understanding you. Why would you treat the Skymaster like a single engine plane on take off? For me the whole point of owning one and carrying around that extra hulk of steel and aluminum is mostly for this phase of flight, ie it is critically important that it will still climb in the event of a loss of a single engine on take off.

Regarding retraction, the data noted above from the O-2 manual suggests you indeed do have a version of a single engine (ie you are descending) if you put the gear in motion on one engine. No such data is quoted in my manual. The airplane is perfectly happy flying along with its legs hanging out and will apparently still maintain a positive rate of climb at Max Gross on one engine in such configuration. So I am confused as to why you would in effect be suggesting you turn your twin into a single by moving the gear handle. Of course once you have some altitude flying an "engine out" single isn't a big deal for 12-15 seconds of retraction time. But as I said, maybe I am just mis-reading your statement above.

[Roger]

I believe the analogy about being like a single engine aircraft is that in certain configurations and scenerios, the Skymaster with one engine out, climbs like a single with one engine out. This would specifically be hot/high or both, on takeoff, one engine out, and the doors in transit. Get it ?

Just this week my gear breaker popped after takeoff, and it was very apparent that it did. Not because some light blinked or horn beeped. But because it was climbing like a wallowing pig with the doors open. I would never like to experience that with an engine out.

I would think this especially so in those aircraft that have the older style single engine driven hydraulic pump, when that engine goes.

[billsheila]

OK, I am a little thick but I get it now. So Tropical and I are in agreement, I think, except he still wants to see the gear in transit ASAP after becoming airborne does he not? So I gather the logic would be get the plane cleaned up ASAP

Roger, re your incident, presumably your breaker wouldn't have popped if the gear were down and locked right? So why not leave them down and don't risk the possible effects of any configuration changes until you gain some altitude...which was my original point.

I checked my manual again and am embarrassed to say it indeed does contain data on the minus 240 ft/minute effect of in-transit climb impact of retraction (on single engine, rear operating) and quotes minus 110 ft/minute (on single engine, front engine operating). What is not quoted is the drag effect of the gear themselves, ie if left down.

Back to your incident, do you think your plane would climb on single engine, other feathered, gear down and locked...or only a cool day?

I like the suggestion of trying this at altitude and figuring it out that way. In the meantime, I will fly a 336 for the first bit of every flight.

[Roger]

Down and Locked is good. Up and locked is good. In transit blows.

Yes the plane should climb with one engine out and the gear down under most scenerios ( ie.. standard day, or not overloaded, etc.. ) Always check your book and CG to be safe just in case.

My scenerio was classic in that I had set my Props and Throttle for cruise climb and was about 450' off the runway (which was sea level by the way) and I put the gear up. I hadn't flown it in about 3 weeks, and for whatever reason, the breaker popped. I knew almost instantly what was happening becuase it almost stopped climbing, looked out at my shaving mirror on the strut fairing, and saw the open door.

Moved my left knee away from the circuit breaker panel and was happy to see the popped breaker . Happy becuase it seemed like a no-brainer. Worse if you have stuck doors and the breaker is in, because at that point your potential for quick fix deteriorates. Popped the breaker back in, and doors closed immed.

I cycled the gear 3 times when at 2000 feet to make sure everything was working, and didn't have any more problems.

Once it happens to you (gear doors stay open) you won't ask the question "why wait" ever again. Sure you don't look like a fighter pilot, but it's worth the perceived humiliation

[tropical]

Originally Posted by Roger

I believe the analogy about being like a single engine aircraft is that in certain configurations and scenerios, the Skymaster with one engine out, climbs like a single with one engine out. This would specifically be hot/high or both, on takeoff, one engine out, and the doors in transit. Get it ?

Just this week my gear breaker popped after takeoff, and it was very apparent that it did. Not because some light blinked or horn beeped. But because it was climbing like a wallowing pig with the doors open. I would never like to experience that with an engine out.

I would think this especially so in those aircraft that have the older style single engine driven hydraulic pump, when that engine goes.

Your analogy is correct.

[JeffAxel]

My POH for a '77 T337G says the penalty for gear down amd locked, doors closed is the loss of 110fpm climb on one engine. The plane will climb on either engine with the gear down amd locked with the doors closed. It will just maintain altitude with the gear in transit if everything goes right. The aforementioned -240fpm is what my POH says as well as the penalty for gear in transit. I am sure loosing the big main gear doors helps some as far as drag goes, does any of the paperwork that comes with the STC say what the difference is?? That would be useful information.

[Ernie Martin]

Two thoughts.

1. I don't think any of us should assume the POH climb rates to be realistic for our aircraft. Those numbers, squeezed to the max by Cessna, are for brand new aircraft, with perfectly smooth (and waxed) skin, perfectly tuned engines, perfect-pitch props, etc. Ours don't fly that good. I assume 100 - 200 fpm penalty for age, plus the adjustments for temperature, pressure density, etc., and I try to fly below max load, so if an engine fails I can get close to the POH numbers.

2. Of the added drag introduced by the gear in transit, I don't know the proportion of the big doors (the ones removed by the STC), but if you've seen a gear retraction test up close, you know it's big. My guess 2/3 of the in-transit added drag is due to the big doors.

Ernie

[aldoradave]

OK guys, it seems I'll have to do it myself! Tomorrow I will give it the big test and report back as soon as I safely land. I'll go up to 10,000 msl with gear down, retard the rear engine to zero thrust, pop the front to full boogie then record my rate of climb. At 10,500 I'll cycle the gear up and note what happens.

Given that there are so many differences in our birds, this is the only rational way to do it anyway. I'll post my results as soon as I can.

[JeffAxel]

Ernie,
No argument from me on either of your points. Don't make assumptions is a good point. In my case, I also don't fly at gross wt. too often, and so also hope for book numbers. But out of curiosity, when I bought the plane, I took it up with an instructor to see what it would do. I was pleasantly surprised, but we were pretty close to gross wt., and the plane did climb at 100-150fpm with the gear down on the rear engine. Later, when I lost the rear engine on a go around in instrument conditions, it climbed out at 350fpm on the front engine, probably 250lbs under gross on a cool day. Turns out the fuel was set up way rich on the rear engine and it choked when I gave it power, came back when I leaned the mixture, thankfully. Made me a Skymaster believer though! Fuel set up is better now too. I am still not sure what the best course of action is with the gear though. I usually leave it alone until all set for cruise climb, then retract it. When I asked about this at Recurrent Training Center, they made the argument that getting the gear up resulted in better climb, and altitude is your friend, and so had no problem with positive rate gear up. They weren't unhappy if you waited either. I guess to each his own. I can wait to pull up the gear myself....

[billsheila]

What are the settings for zero thrust on a NA Skymaster. My instructor dug these up a few years back and I recall keeping a copy, but now can't find it. In my 1965 Owner's Manual, there is no data given.

Thanks to anyone who can help.

[hharney]

Originally Posted by JeffAxel

I am sure loosing the big main gear doors helps some as far as drag goes, does any of the paperwork that comes with the STC say what the difference is?? That would be useful information.

RT Areospace did not provide any new numbers for the gear door removal......fly it by the book!

[Roger]

If the self test is going to start at 10,000' at near gross, with the rear out, and doors open I believe we may have to wait a few days for him to get to 10,500'

[Ernie Martin]

Good point, Roger, since the single-engine ceiling is around 6,000 ft (more with the front out, less with the rear out).

Ernie

[aldoradave]

Originally Posted by Roger

If the self test is going to start at 10,000' at near gross, with the rear out, and doors open I believe we may have to wait a few days for him to get to 10,500'

Dear Roger,

Please note that N84E is a P337 and should have no problem getting from 10,000 msl to 10,500 with rear engine out. If it does I have bought the wrong airplane. My guess is that with the gear door mod it will be easier with the gear retracted.

Dave Dillehay