So after a long decent to Chamerlain it was time to fly my approach. During all of my approaches I clear the throttle during the base leg to ensure the engine doesn't load up with fuel. I did this while on downwind and base while landing at Chamberlain this time because of the long descent thought the clouds.

While on short final I let my speed drop just a couple miles an hour too much so I knew I would need power to flair to a nice landing. When i added power the motor just bogged and I didn't have enough ummph to slow my decent. Stick all the way back...just like Gump says ... SLAMM I was down HARD. Nothing was damaged but it was a really hard landing. From then on I flew my approaches with power, about 1500rpm, and a firm slip.

My first though was that I might have applied power too fast which will make the engine sputter because there in no accelerator pump in the carb, but I am always careful to not get excited and I am very sure that I did not apply throttle too fast.

So my questions are what might have caused this? And those of you that fly planes that do not have accelerator pumps what do you do on landing to prevent this, besides not letting your speed drop.

Jon

whee wrote:So after a long decent to Chamerlain it was time to fly my approach. During all of my approaches I clear the throttle during the base leg to ensure the engine doesn't load up with fuel. I did this while on downwind and base while landing at Chamberlain this time because of the long descent thought the clouds.

While on short final I let my speed drop just a couple miles an hour too much so I knew I would need power to flair to a nice landing. When i added power the motor just bogged and I didn't have enough ummph to slow my decent. Stick all the way back...just like Gump says ... SLAMM I was down HARD. Nothing was damaged but it was a really hard landing. From then on I flew my approaches with power, about 1500rpm, and a firm slip.

My first though was that I might have applied power too fast which will make the engine sputter because there in no accelerator pump in the carb, but I am always careful to not get excited and I am very sure that I did not apply throttle too fast.

So my questions are what might have caused this? And those of you that fly planes that do not have accelerator pumps what do you do on landing to prevent this, besides not letting your speed drop.

Jon

Whee, my Luscombe (8A with an A65) had the same bad habit. I don't remember it ever happening during flight since the forward speed kept the prop spinning and that smoothed out the "studder". It did however, on numerous occasions, quit once I was on the ground and adding power to taxi. I never did find a solution to the problem...but rather learned to accept the nature of the beast. Could you have had some carb ice?
Maybe try not to wait till the last second to make power changes. I used to come in a bit high and slip the livin' piss out of the thing on final (those Luscombe are awesome slippers)...adjust the slip to put you where you need to be on the end of the runway. Make any necessary power changes farther out so the engine has a chance to understand what that knob is for.

That hasn't happend to me yet, but I have had the engine die just after touchdown. I was landing to the south over trees at my home strip, and I didnt want to land real long so I just left the throttle out. Ended up pushing the plane back, and took forever to start it again.

Those stromberg carbs are kinda notorious for that. I know of a guy who pranged his 140 pretty bad cuz it wouldn't take the throttle when he cobbed it for a go-around-- engine kinda bogged, and down he went.

Eric

I had a similar event in a Citabria once. I had been asked to do some automotive traffic pattern photos for the Watsonville Air Show during and after the show. Another pilot offered his 7ECA for the task. We were coming in on short final, back in the days when I hated to waste that first foot of runway, when I felt that sudden sinking feeling of a lost engine. Put the nose down, looked for the prop, but it was stopped horizontally, so was not too visible with only seconds to go. Had to side step to avoid hitting the runway end "light bars" and put it down in the grass. From the back seat I hear, "Oh, just bump the starter, it will start again. Sorry I forgot to warn you about that." I replied, "Thanks for the timely advise."

Turns out he had the problem for a couple of years. I did an inspection between flights and we found the Carb. Heat Box had worn a SLOT where there should have only been a hole for the Carb. Heat Flap hinge. New Heat Box fixed his particular problem.

I know it is a characteristic of the stromberg I was just wondering if guys who have that carb use any different procedure when in the woods, like approaching with power and a slip. I usually fly my pattern a little tight so if I lose power I can glide to the runway without a problem. But when I go to a strip for the first time I fly a "regular" pattern so I don't overwork myself.

I think I'll check my plugs just to be sure and just keep doing what I have been doing. I don't think I was carb ice because I had the carb heat on for a while before I landed.

Jon

whee wrote: the motor just bogged and I didn't have enough ummph to slow my decent. Stick all the way back...just like Gump says ... SLAMM I was down HARD. Nothing was damaged but it was a really hard landing. From then on I flew my approaches with power, about 1500rpm, and a firm slip.
Jon

Been there a few times!!! Outta airspeed, altitude, and options, all at the same time.

Both the Strombergs and the Marvels will do that to you. Little trick I was taught a very long time ago was if/when the engine bogs down when giving it gas from a low RPM, is to retard the throttle all the way back to idle, then slowly advance it, and it'll most always catch and accelerate normally.

Hard to have the discipline to pull throttle back if you're ten feet up and about to prang it in, but it does work. As a rule I don't do power off/glide in approaches. I'd rather feel the engine(s) pulling all the way down, and keep MP and RPM in the green through the flare. Especially if it's cold or real cold.

Gump

Went to Idaho Falls to get my BFR done but the weather was not good so I didn't get it done. I got my Dad to go up with me so I could do some T&G's. It was cold so the plane preformed real good..even got 112MPH true airspeed at cruise power!!! Only issue was I had a tough time getting the thing to take power after the touch so I could go. When it is cold it doesn't take power as good but it has never been that bad. Gumps last post here sheds some light...I was doing power off approaches. Any other ideas?

Don't know how it would work on your plane, but you might want to leave the carb heat on all the time when it's cold and just lean the engine a bit to compensate for the less dense air. In theory the warm air helps to atomize the fuel when it's cold. Of course if there's much dust I'd not recommend it.

Every one of the articles I've read on cold weather flying makes a big point about not closing the throttle until the field is made.

That might not work too well, as them stromberg's don't have a very sensitive mixture control. Some of them have the mixture wired full rich as I recall-- maybe an AD to do so on some airplanes?

Eric

Whee--- what was your mixture set on as you were landing at Chamberlin? If you still had your mixture an lean, when you applied throttle it could have made it act like that. On the other had if you shoved the mixture all the way in ( on full rich) it could have been too rich for that 5765 foot elevation. I have never had that trouble but I could sure see how that would cause some concern. Bob

My stromberg was wired full rich...most luscombes are...but i extended the arm the the mixture cable attaches to to make it less sensitive. It works very well but I still don't lean very often and when I do it's only when I'm over 8000 and going to stay there for a while.

I was at full rich when going into Chamberlain.

I tried keeping the carb heat out during the landings and it helped a little but not much.

My AI said the best thing he ever did to his J-3 was change out the stromberg...

Whee---- I know with my 182 I lean some on landing at some of those high elevation strips but I don't take off or land full rich. I don't know any thing about carbs in your type of aircraft though. It must be set to a lower elevation so I would think a high elevation would effect how it ran. I am curiious about that? Bob

Bob:

From what I have gathered about operating with this carb, you don't do any leaning unless you are set at cruise. Most of the people I have talked with say to leave it rich and don't mess with it. I read a guide by stromberg a while back that discussed how to control the mixture...it says to leave full rich below 5000MSL. I suppose leaning could be effective during takeoff and landing but because it is so sensitive to altitude changes I'm not sure I would mess with it during takeoff and landing.

The sputter at Chamberlain was pretty normal because of the lack of accelerator pump but this past weekend it was way worse.

Whee, does your Luscombe have an A-65/75 engine, or bigger? I believe there's an approval for install a Marvel-Snottler on a C-85 or 90, but not sure if it's via type certificate, STC, or field approval. Might be kinda spendy, but would get rid of this SSS (stumbling stromberg syndrome), give you useful leaning capability, and eliminate that leaky needle that stromberg's seem to often be cursed with to boot.

Eric

The Stromberg in my little C-140 has two mixture settings, too rich and too lean. When I pull carb heat on it get's too,too rich and runs a little rough. I pull the mixture and it runs better. Other than that I leave it in. I haven't had any stumbling on acceleration. Is it possible you may be a little lean at low RPM from a low float setting or something? Lean will definately cause a stumble.

a64pilot wrote:Is it possible you may be a little lean at low RPM from a low float setting or something?

Sounds like something I should look into during the annual. My AI did a complete overhaul on the carb and he knows them pretty well so I figured he did it right but still...

I've got a C-85 in my Luscombe. I've tried to find info on putting a Marvel on a Luscombe a couldn't, then Gump mentioned they sputter too so I quite looking.

The J-3 has a plate that goes over the aircleaner with about a one inch gap.
This takes care of the thing not taking power when it's cold outside. Go to www.Bowersflybaby.com/tech/fenton.htm for lots of hints on these small Continental engines.

Whee,

I have never had that problem with my 140, but I have had that happen in other Stromberg carb'd airplanes. Honestly, I don't know why mine works so well, but I'm not willing to take it apart to find out why. Obviously, I just got lucky and everything on the carb is set correctly.

As far as the leaning goes, you are absolutely right. Don't lean it unless you are at or near full throttle. The Strombergs lean "automatically" as you pull the throttle toward idle from the full throttle position. On my 140, if I pull the throttle back 2" from the full power position it runs pretty close to peak EGT. At that throttle setting, if I even try to move the mixture from full rich, it quickly moves past peak EGT and starts to run rough. You may have run into the same thing? Although our engines will run near idle with the mixture leaned out, if you have to apply power (say for a go-around) the engine will run too lean and possibly quit as the throttle is moved to full power. You can try this on the ground and see what I mean. At idle, pull the mixture to the full lean position. Then try to apply full power rapidly and the engine will most likely quit. I wouldn't make a habit of doing this, as the engine will be most likely detonating for a split second before it quits.

Matt