Focke Wulf 190 80% Scale

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AVI

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Radicaldude,

Are you familiar with the Arthur Bentley drawings for the FW190 series? Excellent, super detailed, well dimensioned drawings, well worth ordering.
 

Radicaldude1234

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Radicaldude,

Are you familiar with the Arthur Bentley drawings for the FW190 series? Excellent, super detailed, well dimensioned drawings, well worth ordering.
Yes sir, I am and can attest to the quality of them. I actually used a set to create the model for the Do 335...but I didn't use them for the FW-190 as the factory drawings I had were accurate down to the millimeter (to spec at least, their jigs might have been tweaked during production for whatever reason).

No matter now, as the fuselage shape is pretty much fixed. What I've done so far is shrunk it down to 85%, converted to the English system (easy), moved all obvious bulkheads to the nearest 16th of an inch (makes building jigs a whole hell of a lot easier), and "Americanized" the cockpit by enlarging the width to 24" (the original was around 22" wide; would be ~19" if scaled directly. So as it is, the current model wouldn't match any historic profile anyways. I'm pretty happy with the shape and am just tweaking it slightly to get as many flat wrapped panels as I can.

Not much structural design going on at the moment, however, as I'm reading up on my dynamic flight stability. I'm replacing the 23000 series airfoils in the original with a Riblett airfoil to try to tame some of the vicious stall/spin behavior that the FW-190 is known for. Unfortunately, this will require some redesign of the tail, though hopefully limited to the horizontal tail.
 

Spinnetti

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Dec 24, 2005
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Took a look at what Mr. Kronk did (may he rest in peace), and it seems that he enlarged the entire cockpit and canopy. It's really hard to tell unless an original was parked right next to it, but the canopy is longer and taller proportionally than the original. He's also able to fly it with the canopy open, which is puzzling as this is strictly verboten in the full size model due to buffeting...

I was also planning a two seater version, though more in the style of the modified trainer version of the original than an enlarged cockpit version like what Mr. Kronk did. The problem is that the canopy rails taper back; in the original, the cockpit rail width was about 25" at the instrument panel and 22.5" where the pilot shoulders are. In my version, its about 26" at the panel and 24" at the shoulders.

The good news is that a trainer version could be accomplished by only redesigning the rear fuselage. The canopy width at where the forward fuselage terminates is about 22". Of course, the rear cockpit width would be limited at that width (which is similar to the cockpit width of an RV-4), but it wouldn't necessitate redesigning the entire fuselage sub assembly. There will be a strange bulge followed by an aggressive taper to meet the tail, though.

View attachment 24956 View attachment 24957View attachment 24958


CAD-wise, I also put the pilot in to see how he/she fits in the cockpit. The guy in the pictures below is a 95th percentile sized man, so 6'3 and 245lb. Personally, I'm 11 inches shorter and more than a hundred pounds lighter, so I'm at the 5th percentile, which means I'll design the cockpit to fit between the 95th and 5th percentiles. I'll be able to fit comfortably (since if this thing gets built, I'll be the only sure customer...); the 6'3 guy, probably not so much as though he'll still be able to operate it safely, the plane will probably fit him like a tight glove. I'm going to try to find a 50th and 5th percentile virtual mannequin to further verify.

I also did the same for the 109, as seen below. The good thing about the 190 is that the cockpit widens as it gets lower. No such luxury exists in the 109, which is consistent with pilot reports of it being barely spacious enough to operate the controls. Of course these are scaled down replicas, which certainly does not help alleviate the problem...almost makes me want to go full scale, until I look at the increased construction and operating costs, that is...

View attachment 24959View attachment 24960View attachment 24961
The beauty of Kronk's bird is that it kept the profile of the single seater, but seats two. the trainer version of the FW is (cough, gag) HORRIBLE! :) I'm the "94%" man, but my wife is only 5'2 for the 2nd seat ;) I really want to build a two seater like Kronk's, but not brave enough to design the whole thing myself.. Rv8 is my design bogey.
 

RJW

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Just a few observations on the FW190 wing mount: The bolt runs through the forward part of the spar cap. It looks aft in the drawing because there is substantial incidence in the design and the cap itself is pretty far aft—about 35% (?) chord. Second the firewall structure to which the wing attaches is very stiff. If I’m not mistaken the firewall frame is a one-piece forging with many other stiffening structures riveted to it. Third, the neutral axis of the spar is probably closer to the upper spar cap than appears. The spar/wing structure is a pretty complex beam that certainly results in non-obvious deflection. Fourth, look at the size of the bolt. It is much too large if designed only to handle tension. So it seems to me that it is also designed to take some shear. And lastly, this is a WW2 weapons platform with a very short useful life. A structure that looks bad to somebody who designs stuff to last 10,000 hours may be just fine for one that must last only 200 hours.

Rob
 

Spinnetti

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Just a few observations on the FW190 wing mount: The bolt runs through the forward part of the spar cap. It looks aft in the drawing because there is substantial incidence in the design and the cap itself is pretty far aft—about 35% (?) chord. Second the firewall structure to which the wing attaches is very stiff. If I’m not mistaken the firewall frame is a one-piece forging with many other stiffening structures riveted to it. Third, the neutral axis of the spar is probably closer to the upper spar cap than appears. The spar/wing structure is a pretty complex beam that certainly results in non-obvious deflection. Fourth, look at the size of the bolt. It is much too large if designed only to handle tension. So it seems to me that it is also designed to take some shear. And lastly, this is a WW2 weapons platform with a very short useful life. A structure that looks bad to somebody who designs stuff to last 10,000 hours may be just fine for one that must last only 200 hours.

Rob
This isn't a replica Fw-190 though... at some sub-scale, its a new airplane that looks like a Fw-190.. I presume it won't be 9,000+ lbs and won't have 1,700 or more hp ;) so given that its all new, I would think there wouldn't be too much gained by the internal design review of the real thing? Terry in Au did a pretty convincing replica from what I understand using the Rv planes design as a baseline? seems like figuring the target weight then using a proven design around that might be a good starting point... e.g. Titan T-51?
 

Radicaldude1234

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Just been working on stability so far, not much to show other than just numbers. It did, however, force me to do components placement, the weight distribution is needed for dynamic stability analysis.

I've also been working on cockpit ergonomics. As a sport plane masquerading as a fighter, cockpit comfort is essential for getting that "one with your machine feel" that people expect. To that end, I'm going with a bracket swivel (swings forward as as you increase seat height; found in British fighters like the Spitfire) and adjustable rudder pedals.

http://i36.photobucket.com/albums/e44/modeldad/Spitfire Seats/46e66a24.jpg~original

2014_0730_Ergonomics.jpg

I'm intending the airframe to weigh ~1400lbs, leaving 3 options in terms of engines:

Option 1 would be to mount a ~500lb engine like M14P (default choice), O-520/540/550, O-720 in short nose configuration. M14P and O-720 should give performance pretty close to the Radial Rocket and Bear 360 (180-200kt max cruise); performance with the O520/540/550 is going to be a bit anemic (think T-34). (Empty Weight: ~1900lb)

Option 2 would be to mount a larger diameter radial like the R985 Wasp Junior (450-525hp/670lb) in a slightly enlarged cowl. At 85% scale the cowl only needs to be widened by 1.5" to take this engine. The holy grail for a short nose FW-190 at 85% would be the double row R1535 Twin Wasp Junior (825HP, ~1000lb; powered the H1 Racer), which would give speeds well into the 220kt range...if only more than 2 of the engines existed. Performance with R985 would probably be similar to Option 1, only with slightly improved climb. (Empty Weight: 2200-2500lb)

Option 3 is to mount a liquid cooled engine like the Falconer V12 (640-1200hp; 700lb dry, guessing ~1000lb with cooling system & accessories) in long nose configuration (FW-190D; TA-152), which should push performance into the 350kt (400mph) range. (Empty Weight: 2200-2500lb)

All three options are designed to mounted on an unmodified fuselage; in fact, the only airframe differences will be the engine mounts, cowling, and a different tail unit (lengthened) for Option 3. The wings, fuselage, and landing gear are standard for all 3 versions.

Thoughts?
 

rv6ejguy

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Jun 26, 2012
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Calgary, Alberta, Canada
Just been working on stability so far, not much to show other than just numbers. It did, however, force me to do components placement, the weight distribution is needed for dynamic stability analysis.

I've also been working on cockpit ergonomics. As a sport plane masquerading as a fighter, cockpit comfort is essential for getting that "one with your machine feel" that people expect. To that end, I'm going with a bracket swivel (swings forward as as you increase seat height; found in British fighters like the Spitfire) and adjustable rudder pedals.

http://i36.photobucket.com/albums/e44/modeldad/Spitfire%20Seats/46e66a24.jpg~original

View attachment 33544

I'm intending the airframe to weigh ~1400lbs, leaving 3 options in terms of engines:

Option 1 would be to mount a ~500lb engine like M14P (default choice), O-520/540/550, O-720 in short nose configuration. M14P and O-720 should give performance pretty close to the Radial Rocket and Bear 360 (180-200kt max cruise); performance with the O520/540/550 is going to be a bit anemic (think T-34). (Empty Weight: ~1900lb)

Option 2 would be to mount a larger diameter radial like the R985 Wasp Junior (450-525hp/670lb) in a slightly enlarged cowl. At 85% scale the cowl only needs to be widened by 1.5" to take this engine. The holy grail for a short nose FW-190 at 85% would be the double row R1535 Twin Wasp Junior (825HP, ~1000lb; powered the H1 Racer), which would give speeds well into the 220kt range...if only more than 2 of the engines existed. Performance with R985 would probably be similar to Option 1, only with slightly improved climb. (Empty Weight: 2200-2500lb)

Option 3 is to mount a liquid cooled engine like the Falconer V12 (640-1200hp; 700lb dry, guessing ~1000lb with cooling system & accessories) in long nose configuration (FW-190D; TA-152), which should push performance into the 350kt (400mph) range. (Empty Weight: 2200-2500lb)

All three options are designed to mounted on an unmodified fuselage; in fact, the only airframe differences will be the engine mounts, cowling, and a different tail unit (lengthened) for Option 3. The wings, fuselage, and landing gear are standard for all 3 versions.

Thoughts?
Which engine can you best afford? I've always liked the D9 myself.
 

Radicaldude1234

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Front Range, Colorado
Sounds like you've been busy. Images?
And for inspiration, here's a hi-dollar Spitfire replica with an Allison and an original (needs TLC) 190D for sale ....
Allison powered Spitfire...there's something blasphemous about that phrase :roll:

No pictures as of yet, mostly graphs and numbers on stability for the last 3 months.

Which engine can you best afford? I've always liked the D9 myself.
The cheapest engine out of the mix is actually the M14P. Engine/Prop combo is about $40K, which is quite a bargain for 360-400HP.

As much as I like the D9, mostly because of the potentially blistering performance, given my piloting experience, insurance, upkeep, and safety, I don't think its a good configuration for a first prototype. Plus, V12 Falconers are not cheap...

The reason for the large engine selection, along with a modular construction style, is mostly because I'm toying around with the idea of offering this replica as a kit or as plans. Nothing set until the prototype flies, though.
 

Spinnetti

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Dallas TX, USA
Allison powered Spitfire...there's something blasphemous about that phrase :roll:

No pictures as of yet, mostly graphs and numbers on stability for the last 3 months.



The cheapest engine out of the mix is actually the M14P. Engine/Prop combo is about $40K, which is quite a bargain for 360-400HP.

As much as I like the D9, mostly because of the potentially blistering performance, given my piloting experience, insurance, upkeep, and safety, I don't think its a good configuration for a first prototype. Plus, V12 Falconers are not cheap...

The reason for the large engine selection, along with a modular construction style, is mostly because I'm toying around with the idea of offering this replica as a kit or as plans. Nothing set until the prototype flies, though.
The cheaper and more realistic it looks, the better the sales potential... Hurry up so I can build one :)
 

Radicaldude1234

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May 30, 2009
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Front Range, Colorado
Hey Radicaldude1234 Just wondering how the plans are coming along? Made any big headway? Love to see what you've been working on since last summer.
Honestly, haven't done much and didn't really pick things back up until last week. I'm still working on the stability of the airplane by creating a spreadsheet that will spit out the numbers I need to analyze the airplane in different conditions (like clean stall, flapped stall, accelerated stalls, at do not exceed speed, etc...). Once that's complete, I can quickly run the studies, but currently my calculations aren't matching with simulated CFD results and I want to know why.

Once the preliminary aerodynamics/stability analysis is complete, I need to come up with a load map that defines the maximum forces exerted on the airplane in the most extreme scenario (which will probably be the Vne-MaxG pullout). Only after that can I go into the actual design of the airframe.

Part of the stability analysis is component placing, though, and I'm spending a lot of time fine tuning locations. It certainly helps to already have the shape of the fuselage. An example is the fuel tank locations shown below. There were originally going to be two fuselage tanks (the second one behind the one shown in the picture), but because the M14P is so light, the rear tank needed to be deleted. To restore the tankage and help with the balancing, two leading edge wing tanks were added. These tanks adversely affect the rolling performance and spin recovery of the airplane, though and are only designed to be used in ferry flights.

2015_0708_ProfileFuel_Tanks.jpg 2015_0708_IsoFuel_Tanks.jpg

The performance looks promising, though. Optimistic projections are a max speed of 285-290kts at 15,000ft. Maximum endurance is 6 hours at around 220kts at ~10,000ft. Which will give you ~1000nm with 95 gal. of gas. This is with the 400HP version of the M14P at a cruising weight of ~2500lb and adjusted for power drop off with altitude.

2015_0708_MaxSpeed.jpg
 

Radicaldude1234

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very nice, what makes 15,000ft such a bad altitude to fly at ? Is it engine related ?
Yeah, I was curious about the bulge there too and I checked and rechecked the numbers with the same results. The engine data actually only goes up to 15000 ft, so the 20,000 ft figure was actually linearly interpolated...which is a fancy way of saying I made a guess.

I guess it just goes to show how sharply the performance on piston engines drop off with altitude. Ironically, performance at altitude was also something that the original FW-190 struggled with. If you want performance up high, though, you can install an turbo normalized IO-550, IO-580, or IO-720. Even if you choose the 350HP IO-550, you should be able to go 360+kts (400+mph!) once you climb pass 25000ft.

Of course, there's also the question of if it is worth it. I suspect that anyone investing in an FW-190 replica isn't doing it to sit in a small unpressurized single-seat cockpit for hours on end at high altitudes to cruise from A to B. Just seems like a very expensive kind of torture...
 

RJW

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Wisconsin and Kansas
I'm intending the airframe to weigh ~1400lbs, leaving 3 options in terms of engines:
Or you could save a ton of money and use a 450HP LS3 with an airboat drive ala Jeff Ackland’s P85. Stick the liquid cooled setup in the smallest round cowl version (A4 I think) and you’d end up with a cheaper, smaller, lighter, and probably faster plane than a D9 replica. You could use a stock-looking fan bolted directly to the prop hub for ground cooling and to hide the liquid cooled installation. There would be plenty of room for an annular radiator or even a couple cheap square radiators fitted near the firewall and ducted to the stock-looking cowl flaps to adjust temps. The ejector stacks would help with cooling too. Just like the real thing.

Rob
 
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