4
$\begingroup$

Embraer recently teased a turboprop aircraft with aft-mounted, open rotor engines. Why would this aircraft not use a pusher configuration?

The reasons that are frequently stated as a benefit for a wing-mounted, pull configuration (e.g. avoidance of disturbed flow from the wings, blown lift over the wings, control surface effectiveness, etc.) would not apply here. To the contrary, it seems to me that re-energizing the exhaust/wake of the engine and maybe to some extent the fuselage would have a beneficial effect.

One possible reason could be that Embraer would like to use an existing engine. In that case turning it around would point the exhaust forward and the intake backwards. That, however, also seems to be a solved problem: the MQ-9 uses the Honeywell TPE331-10GD turboprop engine, which is designed for a pull configuration. Another might be ground clearance during rotation.

Conceptual Rendering of Embraer's proposed new Turboprop

$\endgroup$
8
  • $\begingroup$ In the post you linked, why would ground clearance not affect it? Picture the prop plane further behind and the aircraft rotating/flaring. Another item from the same post and another related post would be too much stability. $\endgroup$
    – ymb1
    Aug 23 '21 at 18:50
  • $\begingroup$ Maybe reword the title question to ask about advantages or disadvantages of each design? Just a suggestion... Because I don't think there is a verifiably "correct" answer that won't be opinion based. Unless someone here is an inside part of the Embraer team, and is willing to publicly share the company's rationale for making the decision. $\endgroup$ Aug 23 '21 at 18:51
  • $\begingroup$ @ymb1 & Michael Hall: Thanks - edits made. $\endgroup$
    – nodapic
    Aug 23 '21 at 19:13
  • $\begingroup$ You will almost certainly get a buzz noise from the wake of the nacelle's pylon. The puller layout will be definitely quieter and it also moves the CG forward a bit compared to prop at the back. $\endgroup$
    – John K
    Aug 23 '21 at 19:22
  • 1
    $\begingroup$ @Koyovis, I agree, but the original question wasn't about a design process, it was about their business decision, i.e. "why did Embraer decide...?" Hence my comment, which is N/A since the edit. $\endgroup$ Aug 24 '21 at 2:58
1
$\begingroup$
  1. Pusher configurations often run into clearance issues. The landing gear is usually further forward of the prop, and while taking off, or flaring to land, the prop has to have enough clearance to avoid prop strike. Usually this is solved by bigger landing gear (more mass) or placing the engine higher (thrust misalignment + usually more mass) but ultimately both solutions lead to the ability to use a larger radius propeller in puller configuration, and the bigger your prop, the better efficiency, so why not use the pusher configuration?

  2. You mentioned an engine that can be used for pusher prop configuration, but, when it comes to mass production and corporate supplier relations - that engine might not be available to Embraer. For instance - Honeywell has an exclusive contract with, say, Boeing or Airbus for that engine. Or - Honeywell cannot produce enough of those engines to fulfill a contract with Embraer, and they are perhaps phasing the engine out for a variety of reasons, so they have no wish to increase production.

  3. Engine cost. Continuation of pt.2 - most turboprop engines are designed to be pullers. This means that they will have a decent amount of common components. Turboprops for pushers are not as common, so there would be a larger amount of unique components, which would drive up design and production costs, as well as maintenance and sales costs.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.