Stuka With Retractable Landing Gear: What If?

[Shortround6]

Pretty much right.

One reason for using retractable landing gear is to get better cruising speed and range. For the Ju-87 this wasn't that big a deal. Most of the time it's targets were close (and not moving) and range and time to target were not important ( sometimes it was but that was often). British, Japanese and US carrier dive bombers operated over larger distances and against targets that could move 20-30 miles an hour from the sighting report location. Higher cruising speeds were a definite advantage for them.

 

[stona]

It would need a completely redesigned wing. Shifting spars and other structural components to make room for a wheel well is never a straight forward proposition.
Steve

 

[tyrodtom]

The JU-87 needed to be at least 100 mph faster at low level to just put it on parr with the fighters it likely to come up against.
Retractible langing gear would add maybe 25 mph, but at what cost ? With the same hp it'd mean reduced payload, more work for the already overworked ground crew, maybe a collasped landing gear ever now and then.
To get up to speeds required so it MIGHT be able to defend itself would require a complete redesign, which the Ju187 was.
All the early WW2 dive bombers were slow, slower, or slowest, to move it from one catagory to the other is not going to help it's battlefield survival..

 

[Tante Ju]

Also having a landing gear that is always down seems pretty practical for a plane that is being shot at by virtually everyone with a rifle or pistol (since 87s were used increasingly close support aircraft, rather than dive bombers). The Il-2 for example had a fairly practical approach of having semi retractable landing gear in U/C gondola. Part of the tire was always out (and I believe, functional), so even if the hydraulics were shot away, it could still make an "assisted belly landing".

 

[Shortround6]

This was not uncommon for some early mono-planes with retracting gear.

P-35;

Northrop BT

Douglas Devastator

Breda BA 65

Avro Anson

GLoster F5/34

some I've missed and a bunch more twins.

 

[stug3]

Wow, that P-35 is pretty cool.

 

[tyrodtom]

If the gear won't come, you got a lot of work ahead for the ground crew to get the aircraft back up on it's gear, and repair the damage.
With a fixed gear, there's a lot less work to do, no collasped gear, unless there's a really bad landing, maybe just flat tires.
I can see the rational for fixed gear on a short range, close support aircraft.

 

[altsym]

I remember reading (sorry can't remember where, therefore cannot verify it) that the pilot of a JU-87G that was about to crash land (after a engine malfunction), jettison the landing gear as they were to come down in deep snow. As soon as the gear let go, the loss of weight drag made it possible to fly back to base.

 

[Balsa]

Actually that rings a bell somewhere's. Might have been in "Stuka Pilot," or "War Planes of the Third Reich," but it does ring a bell.

Retractable gear cannot significantly correct the JU-87's faults without also altering the very things which made it the superior dive bomber. Think about this problem because what other plane is designed to create high lift? The JU-87 incorporates STOL qualities in to the design of the aircraft.

The JU-87 has the so-called Junkers Flaps, or sometimes called the Junkers Type, or Junkers Flying Flaps, or Junkers Double Flying Wing, because that's essentially what the control surfaces are; another small wing, and which is not the same as conventional control surfaces of other aircraft of it's time.

This a Junkers type control system on an Auster.
View attachment 235964

Here are the pro's for the Junkers type control system.

Near zero lag in control input. Higher roll rate than plain ailerons. Shortened ground run when used as flaps (ailerons double as flaps). Favorable effect on main airfoil circulation. In the position of minimum drag the auxiliary wing can actually decrees the drag of the basic wing. No need to seal hinges. Remain effective when the main wing is stalled.

"Over the years Junkers flaps have shown up on many different light airplanes, (mostly home builts such as the Avid Aircraft), and with good reason. The phrase, "one of the most generally satisfactory high-lift devices investigated to date", keeps recurring throughout the NACA reports."

What's not so great is they have slightler higher drag and this of course increases exponentially with speed. They also have a higher pitching moment which is wonderful for a dive bomber and a STOL Aircraft, which an Avid is. The point is it's a high lift, slow speed control system. At high speed the Junkers system becomes dangerous because of flutter.

 

[FLYBOYJ]

Has anyone considered that if this modification was attempted, the wing structure would have to be beefed up to support the landing gear, hinges, uplocks and possibly landing gear doors? Assuming this landing gear would be hydraulically retracted and extended, a hydraulic pump, actuators, fluid lines (and mounting structure), reservoir and accumulator would add some considerable weight. Also keep in mind C/G changes with relation to bomb load and location when the gear is retracted.

 

[Balsa]

Has anyone considered that if this modification was attempted, the wing structure would have to be beefed up to support the landing gear, hinges, uplocks and possibly landing gear doors? Assuming this landing gear would be hydraulically retracted and extended, a hydraulic pump, actuators, fluid lines (and mounting structure), reservoir and accumulator would add some considerable weight. Also keep in mind C/G changes with relation to bomb load and location when the gear is retracted.

FlyboyJ, these things would add lots of weight for sure. I've been thinking about this question of RG, perhaps it's the wrong way, perhaps the attempts to create a faster dive bomber was the wrong path altogether. Maybe adding leading edge slats would have been more profitable?

Here's my answers to the original questions.

Would it need an entirely new wing? (Yes.)
Would it retain its trademark gull wing? (Yes)
What kind of performance with less drag? (Chance of structural failure induced by catastrophic and sudden harmonic flutter induced by over speed of the flight control surfaces) Correctable with a new wing and airfoil, should increase speed significantly but at the cost of increased take off and landing distances, and reduced bomb load.

Anyone else agree?

 

[GrauGeist]

I knew the Ju87C had jettisonable gear for anticipated Naval operations, but I don't recal it being featured on later varients...

 

[Balsa]

Might as well design a whole new dive bomber, or design a whole new dive bomber which would be a two part system which used the new wing for the JU-87, but intended to be the wing for a whole new bomber body at a later time.

Really interesting question though.
Now I'm wondering if another wing from another plane could have been adapted?

 

[Marcel]

I've my doubt if it would have mattered much. I remember they fitted the Fokker D.XXI with a retractable landinggear and it hardly gained any performance. At least not enough to justify the weight increase. I guess it would have been the same with the Ju87. The aircraft was just designed this way.

 

[davebender]

Me-210C / Me-410A dive bomber was cancelled despite being very fast. For Ju-187 or other such new aircraft to receive serious consideration it must be production ready prior to 1942.

 

[Balsa]

You can't increase the speed of the JU-87 without dealing with the flight control surfaces. Flutter could tear the plane apart. It's speed is limited by the design of Junkers flight control system. There's no getting around that. So now you've got to deal with the weight of the RG, as well as redesign the wing entirely, having to compensate for lost lift of the Junkers control system.

Probably the way to go is re-evaluate whether or not speed is necessary. What about the Henschel Hs 123?

 

[stug3]

Did you mean the Hs 129?

Hs 123

 

[GrauGeist]

Like I said earlier, retain air superiority over your target area and you don't need to rebuild the Stuka...

 

[altsym]

I knew the Ju87C had jettisonable gear for anticipated Naval operations, but I don't recal it being featured on later varients...

Useable on most series of JU-87's

 

[fastmongrel]

You get something similar to a Vultee A-31 Vengeance - Wikipedia, the free encyclopedia which was a solid aircraft but was never going to set the world on fire.