1/32 Curtiss SC-1 Seahawk

[Martinnfb]

Slipstream created by propeller is usually dealt with by the angle or the shape of the vertical stabilizer or rather bf trim tab on the rudder. There must be a simple reason, like providing the access for removing the dinghy from its given compartment.  

 

[HubertB]

I assure you that the rear canopy windows were removed for aerodynamic reasons, because of some vibrations and turbulences, Martin. Not to access the raft, when the canopy would have been jettisoned anyway if the raft was needed.

Hubert

[Martinnfb]

I can't provide any assurance, only assumptions.  

However, for some reason, the SC-2 with bubble canopy had an additional/new  dinghy hatch on the side of the fuselage. So my question is, with the unframed bubble canopy there was suddenly no need for prop wash phenomena remedy?

Having said that , if you look at the color picture in my previous post , the raft bag is sitting right there, blocking the slipstream passage with only oner way to access it.

[DocRob]

Could it be, that the drag was too big, when flown with the open canopy? There would be a much better airflow with the rear windows removed.

Cheers Rob

[Martinnfb]

Philosophy starts by finding the things that are prosaic, utterly mysterious.

The only reason to fly with open canopy would be better visibility, that would lead to the new frame-less canopy development and an issued order, "don't do it, so we don't have to cut extra holes into it..."    

 

Mom, how we are going to service the raft? And what will happened to the raft once we jettison the canopy that this this is obviously sitting on?

Look Mom, fabric covering of the raft access hole, can I rip it for better aerodynamics ? 

Oh look Mom, the fabric is still on, sucks to serve on Iowa with such prop wash.

look Mom no drag to speak about  (final phase of landing-drag sensitive).    and that's one big propellor 

 

Look Mom no additional drag to speak about on the take off either and my canopy has no extra holes. (initial catapult assist take-off)

 

 

[BlrwestSiR]

The canvas cover definitely makes sense. The fasteners certainly line up with the holes on the ones without the covering. 

The blown canopy looks like a P-47 bubbletop. 

[HubertB]

Martin,

it was standard, and approved, and even recommended, by the Navy, practice to take off with the canopy open. Just, besides the « old » tradition of flying open cockpit biplanes - which endured for some time -, because pilots wanted to be able to escape quickly an aircraft that had missed its take-off - or experienced a power failure in this critical moment - and chosen to play watercraft rather than aircraft. And they did not trust that much the capacity of a latched canopy to be jettisoned easily in case of an inadvertent ditching. The practice endured until the early jets; the last being able to fly with an open canopy was the F9F-8T, the famous Twogar.

At take-off and landing speeds of these propeller aircrafts, an open canopy did not create that extra drag. Just like the windscreen of a convertible protects its occupants from the relative wind. And without significant turbulences for close to one meter after the windscreen, or more when you add some special aerodynamic devices behind them, like « anti-turbulence nets ». I can testify having run a Porsche Boxster with an open top at 230 kph without any special buffeting (but with some significant noise  ).

The bubble canopy was only possible after the Brits found a way of forming thick perspex, and that was during WWII (around 1943 IIRC). Before that, you had to have a framed structure with panels, like on the SC-1, whereas the SC-2 could benefit from the technological advance. But the SC-2 canopy had a slightly different profile and plan view than the SC-1, simply because it was possible when the SC-2 was developed. Plus it was certainly « cleaner » from an aerodynamic standpoint than one with protruding frames and rivets. As for the SC-1 canopy, the issue, it was found, was some significant turbulences and buffeting, created by aerodynamic interactions. It was also found that removing the rear panels solved the issue, and this was an easy field implementation. Really, I insist, nothing to do with maintenance of the life-raft, which had, on the SC-1 as any other aircraft, to be extracted from its location for this operation.

Hubert

 

[Martinnfb]

Hubert, we all understand why the canopies are open on approach and take off.  You came from guessing to a making solid statements such as " it was found" etc. Can you back it up by any kind of evidence or documentation?  Probably not and yet you insist.

 I provided pictures showing the few facts in contrary to your assumptions.

• There is a raft sitting on the frame. If you jettison canopy, you most likely loose the raft too.
• There is a fabric cover, or whatever is left of it, to provide cover of that particular compartment. 
• Bubble canopy of sc-2 has identical volume and shape as the framed one and does not contain the raft pack which was moved to the fuselage.

You started with a bunch of assumptions and now you stating what was found, by whom, when? With all due respect I am not buying it. 

Try to look at these these rhetorical questions. Why was there a cover? How do you access the raft? Why did they moved the raft into the fuselage with the addition of the bubble canopy? And provide me with some solid base to support your argument.  I will leave it with that.

Carl apologies for polluting your build thread.

[HubertB]

Martin,

You know me enough now to know when I make conjectures - which I then state as such - or when I relay information and knowledge gained from others’ expertise. And when I do not know about a subject, I just either say so, or just simply shut up.

I’ll post the relevant scan of the « Naval Fighters » book when I have more time.

Hubert