# Stuka With Retractable Landing Gear: What If?



## stug3 (Jun 12, 2013)

Would it need an entirely new wing?
Would it retain its trademark gull wing?
What kind of performance with less drag?


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## Milosh (Jun 12, 2013)

See Ju187.


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## davebender (Jun 12, 2013)

There were several WWII era dive bombers with retractable landing gear. None could match Ju-87D overall performance for payload and weapons accuracy. I cannot help but wonder if fixed landing gear contributed to Ju-87Ds outstanding accuracy.


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## GregP (Jun 12, 2013)

Not even the reliably accurate Val? It was easily the most accurate Naval dive bomber of the war.


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## davebender (Jun 12, 2013)

Val dive bomber could probably match Ju-87D accuracy but it routinely carried only 1/4th the payload (250kg rather then 1,000kg). That's a huge difference in capability.


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## davebender (Jun 12, 2013)

*Historical IJN D4Y.*
500kg bomb bay.
2 x 7.7mm forward firing machineguns.
1,400hp Aichi Atsuta V12 engine. Essentially a modified DB601 clone.
342mph max speed.

D4Y was a nice aircraft but I would make it a bit larger. Might not fit on a CV elevator but that's not a problem for land based German dive bomber.

*Hypothetical D4Y writ large.*
1,000kg bomb bay. Matches Ju-87D but bomb is carried internally to improve speed and range.
3cm Mk103 high velocity hub cannon. 
DB603 or Jumo213 engine. 2,000hp Jumo222A engine would be better still. 
Optimum performance @ 3,000 meters.
~350mph max speed.
Armor protection at least as good as Ju-87D.
Internal fuel capacity adequate for combat radius of 250 miles with 1,000kg bomb. Can be extended further with drop tanks under wings.
Rear firing remote control barbettes similar to Me-210.


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## Airframes (Jun 12, 2013)

Getting back on track and away from the bomb load, which wasn't the question, then 1) Yes. 2) Probably not and 3) probably no significant change.


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## stug3 (Jun 12, 2013)

davebender said:


> There were several WWII era dive bombers with retractable landing gear. None could match Ju-87D overall performance for payload and weapons accuracy. I cannot help but wonder if fixed landing gear contributed to Ju-87Ds outstanding accuracy.



Interesting that the Val also has fixed LG which supports your theory.


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## tyrodtom (Jun 12, 2013)

No one even mentions the major factor when it comes to hitting the target. Pilot skill .


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## stug3 (Jun 12, 2013)

Junkers Ju 187 - Wikipedia, the free encyclopedia

_The project was cancelled by the Reich Air Ministry in autumn 1943 because the aircraft's projected performance, when fully loaded, was estimated to be no better than the latest Ju 87 D variant (estimated maximum speed: 248 mph (399 km/h))._

Maybe a different wing would be needed to reduce drag, but still carry an adequate load.

Ju187


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## bobbysocks (Jun 12, 2013)

does anyone have a cut away of the wing? to put a well for the wheel to retract could cause problems with routing other components. or the wing might need to be made thicker. how does what you gain in the reduction of drag compare to the weight added with the addition of hydraulics and retractable gear? and more importantly what do you expect to gain? the plane was a slower ac by design....what will gaining 10 to 25 mph do for the mission of the plane?


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## altsym (Jun 12, 2013)




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## meatloaf109 (Jun 12, 2013)

My answer is; sure, why not. But it probably would have still been an easy target for modern fighters.


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## stug3 (Jun 12, 2013)

bobbysocks said:


> what do you expect to gain?



speed=ability to avoid enemy fire, but meatloaf is probably right.


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## stug3 (Jun 12, 2013)

Ju-87D3


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## GrauGeist (Jun 12, 2013)

You have to have a wing cross-section that would allow the gear to retract. Even creating a faired gear housing, like on the Il-2, introduced a certain amount of drag...so you'd probably end up creating a whole new airframe.

Your best bet is to stick with what works, and create a safe environment for it to operate in by holding air supremacy...


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## Shortround6 (Jun 12, 2013)

As a bit of a reality check a Fairey Fulmar had a wing 1 sq ft smaller than a Ju-87, that is ONE not ten or even two. With a 1300 hp engine it could do 272mph at 7250ft _CLEAN_. once you hang 1 to 5 bombs underneath the speed goes down hill in a hurry. 

Retractable gear would help range and speed a bit but since the Ju-87 rarely operated at great distances and the increase in speed is still pathetic when compared to a 1942 or later fighter it sort of gets to the why bother point.


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## stug3 (Jun 13, 2013)

Talk about drag...

agent crew cabin










torpedo 300 litre drop tanks






Universal wing mounted Schloss ejector rack with WB 81B gun pod


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## Balsa (Jun 13, 2013)

The corsair has retractable gear and it's gull winged so there's no technical reason RG could not have been added, but there are many associated problems doing this by modification to an existing design. For one thing, the main fuel tanks of the JU-87 are on the inboard sides of the inverted gull wing. Second and most significant was the JU-87 use the Junkers double wing configuration; the flying ailerons and flaps were built in drag, and no amount of sleeking up the undercarriage was going to avail much unless those were altered.

Even though major changes would have been needed, the Germans could have taken lessons from both the Japanese and the Russians in making alterations to the JU-87. The ailerons and flaps could have been incorporated as in a conventional aircraft, a significant reduction in bomb loading would have really helped range when it could have been used, and the RG added to these alterations should have boosted the performance significantly.


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## Tante Ju (Jun 13, 2013)

Actually fixed landing gears were preferable for a dive bomber - they helped creating drag, and as odd as it seems, this is good for a dive bomber. It can maintain and limit speed in dives, increasing accuracy, and can have a very strong wing to sustain heavy loads and pull-outs from vertical dives.

And as SR noted, 400 or 450 km/h is pretty irrelevant when fighters can do 600 anyway AND when your typical bomber will cruise at 200-250 in practice... didnt B-17s cruise at about 180 mph in formation? It just does not make any difference.


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## Shortround6 (Jun 13, 2013)

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.


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## stona (Jun 13, 2013)

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


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## tyrodtom (Jun 13, 2013)

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..


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## Tante Ju (Jun 13, 2013)

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".


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## Shortround6 (Jun 13, 2013)

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.


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## stug3 (Jun 13, 2013)

Wow, that P-35 is pretty cool.


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## tyrodtom (Jun 13, 2013)

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.


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## altsym (Jun 13, 2013)

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.


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## Balsa (Jun 13, 2013)

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.


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## FLYBOYJ (Jun 13, 2013)

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.


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## Balsa (Jun 13, 2013)

FLYBOYJ said:


> 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?


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## GrauGeist (Jun 13, 2013)

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


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## Balsa (Jun 13, 2013)

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?


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## Marcel (Jun 13, 2013)

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.


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## davebender (Jun 13, 2013)

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.


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## Balsa (Jun 13, 2013)

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?


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## stug3 (Jun 13, 2013)

Did you mean the Hs 129? 






Hs 123


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## GrauGeist (Jun 13, 2013)

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


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## altsym (Jun 13, 2013)

GrauGeist said:


> 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


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## fastmongrel (Jun 13, 2013)

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.


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## stug3 (Jun 13, 2013)

Peter C. Smith- Home

Ive read a few books by Peter C. Smith, he always said the Vengeance was highly regarded by Australian RAF crews.


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## Civettone (Jun 13, 2013)

altsym said:


> Useable on most series of JU-87's


Are you sure about this source? I believe there never was a Ju 87D-7 or -8.

Two point I would like to add:
- the Stuka had a lot of problems with its landing gear. A lot of undercarriage failures. Maybe this was connected to the fact that the undercarriage was designed to come off during crash landing, thereby avoiding the plane overturning.
- The Stuka was a very heavy aircraft. So relatively the added weight of a retractable landing gear would be low. It could also be a simple mechanism, retracting backward with the wheels protruding slightly to increase its survival chances.

Kris


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## Shortround6 (Jun 13, 2013)

stug3 said:


> Peter C. Smith- Home
> 
> Ive read a few books by Peter C. Smith, he always said the Vengeance was highly regarded by Australian RAF crews.



It may have been better than generally given credit for but a 275 mph top speed isn't going to do much for evading enemy fighters.


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## altsym (Jun 13, 2013)

Civettone said:


> Are you sure about this source? I believe there never was a Ju 87D-7 or -8.


Yep.

The D-7 was a ground attack aircraft based on D-1 airframes upgraded to D-5 standard (armor, wing cannons, extended wing panels), while the D-8 was similar to the D-7 but based on D-3 airframes. The D-7 and D-8 were both were fitted with flame dampers, and could conduct night operations.


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## davebender (Jun 13, 2013)

Any dive bomber should be heavier then a fighter aircraft of equal size. You need structural strength to survive pull out from dive. Armor to protect against ground fire adds weight too.


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## Civettone (Jun 13, 2013)

altsym said:


> Yep.
> 
> The D-7 was a ground attack aircraft based on D-1 airframes upgraded to D-5 standard (armor, wing cannons, extended wing panels), while the D-8 was similar to the D-7 but based on D-3 airframes. The D-7 and D-8 were both were fitted with flame dampers, and could conduct night operations.


It has been a long time ago, but I remember hearing from Junkers experts that the D-7 and D-8 were not official designations and may well have been errors which only appear in non-official sources. The correct name was the D-5N IIRC.
Cannot say more about it, but that is what I distinctly remember. 

Kris


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## altsym (Jun 13, 2013)

No problem. I guess its up to the guy writing the 'official document'. I seen docs that refer to the 109 for example as BF Me.


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## Dogwalker (Jun 14, 2013)

stug3 said:


> Would it retain its trademark gull wing?
> What kind of performance with less drag?


To have an idea, you can see to the Breda 201, that was projected with the goal to have an italian equivalent of the Ju.87, but able to self-defending after the release of the bomb. It was DB.601 engined, was smaller and lighter than the Ju.87, has the gull wing, the retractable undercarriage, a very streamlined radiator, and was even single seat.
The aircraft was considered agile, and accurate in bombing, however, with all the aerodinamic refinements, the max speed was of only 460km/h, and was then considerer unsatisfactory (the request of the Regia was for at least 500 km/h), and, for self-defending capabilities, not compensating the lack of the rear gunner. So the Regia preferred to buy the Ju.87.

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## Milosh (Jun 14, 2013)

Iirc, the Stuka could dive at 400mph without bits and pieces coming off the a/c.


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## GrauGeist (Jun 14, 2013)

The Stuka could dive at a near 90 degree dive without wanting to "nose-under" unlike many dive bombers of it's time, had a "auto-assist" to help the pilot pull out of it's dive and it could carry a thousand KG bomb load...making it a formidable weapon...

Alot of this was due to it's weight and design...once you start fooling around with this, you lose certain attributes and you're back to square one. If you want somethng that will fly fast and shoot up the bad guys, then sling a bomb under a Fw190...if you want to put a neat hole in a target with great accuracy, then put the Fw190 above the Stuka while it does it's job...


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## fastmongrel (Jun 14, 2013)

stug3 said:


> Peter C. Smith- Home
> 
> Ive read a few books by Peter C. Smith, he always said the Vengeance was highly regarded by Australian RAF crews.



Not dissing the Vengeance stug3 just saying it was similar to a potential retractable undercarrige Stuka and it didnt exactly break any speed records. I wouldnt want to be flying either on the Russian front or the Western front too much pointy supersonic metal flying around to be slowly coming down in a vertical line.


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## stona (Jun 15, 2013)

Civettone said:


> It could also be a simple mechanism, retracting backward with the wheels protruding slightly to increase its survival chances.
> Kris



Take a look at the plan of the wing. It's not the U/C mechanism that is the problem, it's where the U/C is going to go.

Retracting backwards for example would compromise structural elements of the wing.

Cheers

Steve


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## Civettone (Jun 15, 2013)

Ah, I guess you would need a new wing design then! 



Kris


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## altsym (Jun 15, 2013)

stona said:


> Take a look at the plan of the wing. It's not the U/C mechanism that is the problem, it's where the U/C is going to go.
> 
> Retracting backwards for example would compromise structural elements of the wing.
> 
> ...


Unless those spars were boxed in.


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## Civettone (Jun 15, 2013)

Boxed in? What does that mean?


Kris


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## altsym (Jun 15, 2013)

Well you can notch the spar for clearance, then you weld a cap onto it with gussets to give its strength back. Never say never lol.


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## GrauGeist (Jun 15, 2013)

altsym said:


> Well you can notch the spar for clearance, then you weld a cap onto it with gussets to give its strength back. Never say never lol.


Look at the wing's design as it stands. Very rugged and capable of supporting the weight of the aircraft and it's loadout in addition to sustaining tremendous forces as it executes it's dive/pullout.

Notching the spar will weaken the wing even if it's boxed, capped, gusseted, etc...


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## altsym (Jun 15, 2013)

IMO it can be done, no problem. But with the early success of the Stuka, there wasn't a need for gear redesign. Also, with the fixed landing gear, its probably one of the reasons it didn't nose under in a near vertical dive, and the drag limited dive speeds and to help pull up after the dive (the gear wants to pitch the nose up).


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## tyrodtom (Jun 15, 2013)

I cannot see how that landing gear would tend to pitch the nose up.
I've seen pilots apply nose up correction, and trim when they drop the landing gear, I can't what's so unique about the Ju87 landing gear that it would do the opposite.


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## GrauGeist (Jun 16, 2013)

The gear had nothing to do with the Stuka pulling out of a dive and it had a dedicated system of dive brakes to control it's dive.

When the pilot released the bomb and pulled back on the controls, the auto-pilot took over as the pilot "grayed out" from the G forces and returned the aircraft to a level attitude, which by that time, the pilot had regained control.


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## altsym (Jun 16, 2013)

Yes, but I though of the design of the Stuka's fixed gear made the nose want to pitch up in a dive.. ahhh perhaps I'm just over thinking it lol.


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## GrauGeist (Jun 16, 2013)

If anything, it would create a form of drag that would induce a "nose down" attitude, but the airframe was designed with all that taken into consideration.

On the Eastern Front, the "spats" (wheel covers) were removed because of the mud-fouling. This actually created a noticable (noticable, but not significant) change in it's handling. So the landing gear as fitted to the airframe had been taken into account when the design was finalized and put into production.


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## Civettone (Jun 16, 2013)

Maybe this is a possible compromise... 
Gentlemen, let me present to you the Saab 17 dive bomber:












Kris


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## l'Omnivore Sobriquet (Jun 16, 2013)

Balsa had it right : "You can't increase the speed of the JU-87 without dealing with the flight control surfaces."
Which would mean a new aeroplane, the Ju-187.
Yet a crude retractable landing gear modification on the Stuka was certainly possible, like the one on this Saab 17, 'at worst.'

As it was, the Ju-87 with its simple fixed gear, wonderful control surfaces for low speeds, short ranged front-line operations, and excellent precision, and good bomb carrying capacities thanks for the lightweight stiff undercarriage, made a good package with little to change.

However, there was one instance where it was'nt 'front-line short-ranged operations' at all, and it was the Battle of Britain. 
There, on I think two occasions but certainly on one famous occasion, the Stukas that had been doing quite a good job under protection until then, missed their Messerschmidt escort, and where heavily pounded by Hurricanes. The Lufwaffe crews put on a good show trying to shake off their attackers, but the Hurricane boys had other intentions, and where dedicated to finish them all down to the last. Very few Ju87s survived.
On that occasion, or these occasions, some extra speed even minimal given by a crude retractable LG would have shortened their martyrdom, bringing them out of range from the RAF fighters sooner, and limiting losses.
On that very occasion the Lufwaffe command, facing the disaster, decided to withhold further Stuka operations 'until the invasion begins'.
Had Stukas been modified with retractable landing gears, 'at worst' in the Saab 17 fashion, the decision that night might have been... "anders", as they say. And the story flowing from those crucials days, who knows, "ganz anders."

Point #2 : in the last part of the Pacific war, F-4U Corsair pilots did engage in dive bombing, against lightly 'ack-ack' defended pinpoint targets, difficult to reach otherwise in 'horizontal' attacks. Then they found their short and sturdy undercarriage most handy, as an efficient dive brake... 
So in a way, yes... an extended undercarriage does provide a good way to enhance efficiency of dive bombing... while retractable ones are another one to win battles. 
Simply put!

Good remarks all the way through this thread. And pics !


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