Augmentors on 310N

Home 2024 Forums Opening Section Maintenance Issues Augmentors on 310N

Viewing 13 posts - 1 through 13 (of 13 total)
  • Author
    Posts
  • #83818

    My 310N has augmentors on them. Something that I’ve wondered is what their perceived function is on the aircraft, and if they’ve been shown to actually do that or not. I’d think that they would add drag and slow the plane down a few knots, just looking at the extra drag they provide.

    Do they actually help performance or anything else? If not, would it be legal to have a mechanic remove them, or would that require a 337? I’m guessing I know the answer already, but be curious what the gurus say.

    Thanks,

    #96275
    rwelsh
    Participant

      I thought Cessna did away with the through the wing augmenters in 1967 and went to underwing exhaust. maybe Cessna kept them until later.

      #96279
      quote RWELSH:

      I thought Cessna did away with the through the wing augmenters in 1967 and went to underwing exhaust. maybe Cessna kept them until later.

      You make me realize I’m probably using the wrong term.

      The 310N has underwing exhaust (thankfully). It has what I thought were called augmentors that go underneath the plane. The exhaust pipes dump into these. I notice that 310s a few years earlier than mine that still have the underwing exhaust don’t have these parts on them, you just have the little exhaust stacks poking out. It would seem that arrangement would be more aerodynamic.

      If you look in my profile picture carefully, you can see the parts I’m talking about on the left engine. They hang below and add some drag.

      #96289
      quote TDUPUIS:

      quote RWELSH:

      I thought Cessna did away with the through the wing augmenters in 1967 and went to underwing exhaust. maybe Cessna kept them until later.

      You make me realize I’m probably using the wrong term.

      The 310N has underwing exhaust (thankfully). It has what I thought were called augmentors that go underneath the plane. The exhaust pipes dump into these. I notice that 310s a few years earlier than mine that still have the underwing exhaust don’t have these parts on them, you just have the little exhaust stacks poking out. It would seem that arrangement would be more aerodynamic.

      If you look in my profile picture carefully, you can see the parts I’m talking about on the left engine. They hang below and add some drag.

      If memory serves, Jack Riley, Sr. developed the under wing exhaust system with the augmenters as a part of his “Riley Rocket” mod, where he installed 400 hp Lycoming IO-720’s in the early model 310’s. Cessna later adopted the mod in the 1964 C310I. The augmenters turn the exhaust stream into thrust and add a few knots. They should not be removed – and it probably is not legal to remove them anyway.

      #96292
      quote GPARKER:

      If memory serves, Jack Riley, Sr. developed the under wing exhaust system with the augmenters as a part of his “Riley Rocket” mod, where he installed 400 hp Lycoming IO-720’s in the early model 310’s. Cessna later adopted the mod in the 1964 C310I. The augmenters turn the exhaust stream into thrust and add a few knots. They should not be removed – and it probably is not legal to remove them anyway.

      Good background info, thank you for that.

      I do wonder whether the extra knots would actually happen, or if it’s just an idea. On a turbine that’ll happen, but the airflow is significantly higher. The airflow on a piston engine is significantly less. It’d seem to me if that idea worked so well, more piston planes would be so equipped. The augmentors will add drag, and so they’d need to produce enough thrust to overcome that drag and then some. Makes for an interesting engineering question.

      #96296
      quote TDUPUIS:

      quote GPARKER:

      If memory serves, Jack Riley, Sr. developed the under wing exhaust system with the augmenters as a part of his “Riley Rocket” mod, where he installed 400 hp Lycoming IO-720’s in the early model 310’s. Cessna later adopted the mod in the 1964 C310I. The augmenters turn the exhaust stream into thrust and add a few knots. They should not be removed – and it probably is not legal to remove them anyway.

      Good background info, thank you for that.

      I do wonder whether the extra knots would actually happen, or if it’s just an idea. On a turbine that’ll happen, but the airflow is significantly higher. The airflow on a piston engine is significantly less. It’d seem to me if that idea worked so well, more piston planes would be so equipped. The augmentors will add drag, and so they’d need to produce enough thrust to overcome that drag and then some. Makes for an interesting engineering question.

      I talked with Jack Riley, Sr. about them when I visited him in 1975. He told me the augmenters were a big improvement. They flew the modified airplane both with and without augmenters before deciding to include them. The fact that Cessna adopted them is also testimony to their effectiveness. I was flying a 1964 C310I and thinking about either converting it or buying a C340. I liked the Riley C340 (310 HP with intercoolers-the original 340 was 285 hp with no intercoolers) but it had very little useful load as the gross stayed at 5,990#. So, I would up buying a Navajo. Great airplane with bullet-proof engines – Lycoming TIO540-A2B’s.

      #96297
      quote GPARKER:

      I talked with Jack Riley, Sr. about them when I visited him in 1975. He told me the augmenters were a big improvement. They flew the modified airplane both with and without augmenters before deciding to include them. The fact that Cessna adopted them is also testimony to their effectiveness. I was flying a 1964 C310I and thinking about either converting it or buying a C340. I liked the Riley C340 (310 HP with intercoolers-the original 340 was 285 hp with no intercoolers) but it had very little useful load as the gross stayed at 5,990#. So, I would up buying a Navajo. Great airplane with bullet-proof engines – Lycoming TIO540-A2B’s.

      More good information, thanks!

      Yep, the Navajo engines are bulletproof. Got a lot of time running those.

      #96298

      The point of the augmentors was to eliminate the need for cowl flaps. Look at early aerocommanders/apaches/aztecs/. It was in vogue in the 50’s to “reduce pilot workload” by eliminating the need for cowl flaps. As the exhaust exicted the cowl it pulled more air accross the cylinders and the cooling was in direct relation to the exhaust flow/power being used. The idea worked fine except it corroded mufflers on the overwing exhaust 310s.The lower tubes on the later 310’s still did the same thing but the tubes corroded insted of the airframe. I guess tha’s a plus.

      #96303
      quote bnowlen:

      The point of the augmentors was to eliminate the need for cowl flaps. Look at early aerocommanders/apaches/aztecs/. It was in vogue in the 50’s to “reduce pilot workload” by eliminating the need for cowl flaps. As the exhaust exicted the cowl it pulled more air accross the cylinders and the cooling was in direct relation to the exhaust flow/power being used. The idea worked fine except it corroded mufflers on the overwing exhaust 310s.The lower tubes on the later 310’s still did the same thing but the tubes corroded insted of the airframe. I guess tha’s a plus.

      We’re talking about the lower tubes, not the over-wing augmentors. And seeing as there are several 310s that don’t have the under-wing tubes (but do have exhaust that exits under the wings), I’m not sure if that’s the case.

      I hadn’t thought about it being a fad to reduce pilot workload, but that makes sense. For me, I just get used to one or the other.

      #98896

      My 310 I has the augmentor tubes and in comparision to a plane with cowl flaps, seems to cool better on the ground but not as well in the climb. In the Texas summer time I rarely see high cylinder temps during taxi but do have to keep indicated airspeed over 110 knots in the climb.

      #108717

      Ted, As a new member I thought I’d offer one more comment even though your question is a couple years old. I also have a 310N and what I was told is that the real reasons for the augmenter is to help with engine cooling and provide a quitter cabin. With the exhaust going only part way down the tubes a venturi effect is created which helps to pull air thru the engines. I suspect that’s one reason there are no cowl flaps.

      #108751

      Augmentor tubes on every airplane I’ve flown that had them were a function of cooling. Thrust really can’t be created by them but they may reduce the overall drag equation as a by-product which would result in a forward lift component. Total bonus!

      Otherwise I’ve always understood augmentor tubes to serve to draw air out of the cowl therefore improving flow over the engine ahead of it. When shoehorning a bigger motor in to a given space this could obviously become a necessary feature. They usually make for gutsier sound, too. That doesn’t suck.

      #108964

      I have a 310Q with augmentors and from everything I’ve read, they were implemented for three reasons.

      1) Aid in cooling the engine without needing cowl flaps.
      2) They act as an exhaust muffler and supposedly reduce exhaust noise. (Mine is loud as heck but that may be do in part to the colemill conversion)
      3) By allowing air to continuously flow through the engine nacelles, through the cylinders and down & out of the bottom they affectively reduce drag by reducing the pressure that would normally build up in the nacelles. In other words, rather than allowing ram air to build up pressure in the nacelle, it exits thus reducing drag.

      I’ve looked into having them removed. I spoke with a fellow in Kansas that stated he’d been trying for years to get FAA approval to remove them. He was denied even though he had data showing that the engine temps, etc. were fine. They are heavy pieces of what I believe are stainless steel. And… as another member mentioned, they throw all of the exhaust up under the wing and create a mess as well as corrosion issues.

      My two cents,

      Jose

    Viewing 13 posts - 1 through 13 (of 13 total)
    • You must be logged in to reply to this topic.