Revising fw 190 A layout to make a general purpose stunt plane.

[OwenN]

I am winding up all my other threads except the one titled "wing loading ****" and continuing here.

This is my latest layout for the FW 190. I have "de-uglified" it a bit:
Removed the front upper gun deck;
updated the canopy design;
flattened out the joggle in the rear fuselage;
smooth the motor cowl;
fattened the fuselage overhead profile a bit.

Wing , tail, tailplane up in dimensions. Wing layout taken from Severesky Guardsman (later Republic) USA, shortened a bit. - This is a semi-elliptical layout.
Wing area is up 18 %, mean chord up 29%, wing shortened 8% This is based on getting a 7 inch diameter cowl and 50 inch wingspan.
Overall the scale is 1:7.65 of the full size aircraft.

I have also shortened the front undercarriage to suit a 14 inch prop, and make it usable for landing and takeoff on grass. wheels are 3.5 inch diameter. The original aircraft is really raked, and a guaranteed tripover on grass.

The original plane has an 11.3 ft prop, on a small aircraft.
The 14 inch prop scales to 9 ft in diameter.

Wings are also raised a bit, thickened, and dihedral reduced. To be electric powered, 4 kg thrust, 10,000 rpm, 0.9 N-m 1 kW -probably 6S, 60 amps?

Weight aim is 1.5 to 1.6 kgs - 3.5 lbs.

It should have low enough wing loading to do away with the flaps.
loading is 15.4 oz/sq ft, ignoring the area contribution of the fuselage. -Is this the usual way of working it out?
The fuselage is not a very good lifting body, with super-low aspect ratio. The drag would be more than the lift.


I also found that the Mustang was originally built by Curtiss, later amalgamated with North American.

Also , there was a (possibly) radial variant of the P40 Hawk -though photos and plan drawings may be mislabelled-I will
do some more Google research.

This is where I got the nose length to canopy dimension.(this was a Lavochkin La 5 -Russian.-a similar-looking plane).

I propose to keep the main gear retract. Possibly I could pinch the tailwheel retract off a 1.2 m mustang model-
about the right size? - you can buy the separately from Banggood.

Their retracts are also much cheaper than the I-flite ones you get in NZ.

How do the gear doors normally get opened and closed?
I was working on a wire lever arrangement being pushed by the wheel, but that is
tricky, and likely to leave a gap.

Can you used staged actuators?

It has to open before the gear starts to move, and close after the gear has finished lifting?

Also, I want to conceal the rudder horn and the elevator horns.
I have heard of the kinked wire method for the elevators. That should work with a slot in the back of the elevator, to allow for the angle.
What wire thickness do you need to cover about 10 inches? I was thinking 2mm (80 thou)
Would this work, or is there a better way?

I could use a similar trick with the rudder, with a wire bent to 45 degrees, and a long slot to fit.
The rudder only needs to go 30 degrees each way. The wire needs to be twisted a bit more-over 90 degrees total.
Again, is there a better way to do this?

The undercarriage mod does make them look a bit stumpy, but more in line with larger planes like the Hawker Tempest.

What do you think?
I have removed most of the quirks that make it recognisable as a FW 190, and it looks more like a generic ww2 fighter, but more attractive than most.
This does not replace my current build, but I thought I would do a little planning for the next one!

ut

 

[OwenN]

I have mixed up Lavochkin (miss-labelled) and P40 planes. here is a picture of one which is more P40-like. This could be in french colors,
but I don't think it is a french plane.The wheel pods and fuselage back from the front of the cockpit are all P40.
The Lavochkin side and rear window details are different, and the watercooled version had a mid-rear radiator like the Mustang.

 

[Flyingshark]

According to the caption of that picture, those are French Air Force Hawk 75s. (So, the U.S. designation would be P-36.)

 

[OwenN]

According to the caption of that picture, those are French Air Force Hawk 75s. (So, the U.S. designation would be P-36.)

Aha! I will look at the history of the Curtiss hawks. The airframe seems almost identical from P35 to P40.

Further to the FW 190 model: It needs a front fan, inner 66 mm, outer 115 mm-this also disguises the missing radial engine.
generally, plastic fans come as 120mm, with a smaller center.
Also, an electric motor is covered by the spinner.
You really need a standoff drive extension, and diverter cooling rings to direct air into the motor.
Anyone seen a setup like this? I have seen chuck-like extensions for smooth shafts.
If a motor has these specs, usually it has a threaded shaft. Also, I would like to find a motor with a very wide rpm range,
to get good static thrust, and enough pitch speed. 1800 KV plus would be needed, 6S, and possibly a step up from the 2806.5
quadcopter motor. They are not up to spinning a 14 x 5 prop. Any suggestions?

Cooling is not so bad with models of US radial-motored planes, as they generally don't use spinners.
For balance, the batteries would also fit inside a 7 inch cowl.

It that wasn't enough to get a good balance, the nose could be extended several inches. - you could get most of the "gubbins" ahead of the wing. -You are sort of replacing an 850g motor, and the electric internals are around 500g, unless you use a huge battery-
Here is a good one: 5500 mWh, 25C, 6S, 856 g, $219 nz. That could push the design weight over the 1.6 kg (3.5 lb).
I still want to have more than 1 g excess thrust, or 2 g overall, to get good prop-hang capability.

 

[mackaiver]

Aha! I will look at the history of the Curtiss hawks. The airframe seems almost identical from P35 to P40.

Further to the FW 190 model: It needs a front fan, inner 66 mm, outer 115 mm-this also disguises the missing radial engine.
generally, plastic fans come as 120mm, with a smaller center.
Also, an electric motor is covered by the spinner.
You really need a standoff drive extension, and diverter cooling rings to direct air into the motor.
Anyone seen a setup like this? I have seen chuck-like extensions for smooth shafts.
If a motor has these specs, usually it has a threaded shaft. Also, I would like to find a motor with a very wide rpm range,
to get good static thrust, and enough pitch speed. 1800 KV plus would be needed, 6S, and possibly a step up from the 2806.5
quadcopter motor. They are not up to spinning a 14 x 5 prop. Any suggestions?

Cooling is not so bad with models of US radial-motored planes, as they generally don't use spinners.
For balance, the batteries would also fit inside a 7 inch cowl.

It that wasn't enough to get a good balance, the nose could be extended several inches. - you could get most of the "gubbins" ahead of the wing. -You are sort of replacing an 850g motor, and the electric internals are around 500g, unless you use a huge battery-
6S 6,000 mWh???

let me know when the plans are out id love to test them and put them through my rigorous testing program.
https://forum.flitetest.com/index.p...s-rigorous-testing-program.66077/#post-628150

 

[b-29er]

Aha! I will look at the history of the Curtiss hawks. The airframe seems almost identical from p35 to p40.

Further to the fw 190 model. It needs a front fan, inner 66 mm, outer 115 mm-this also disguises the missing radial engine.
Also, an electric motor is covered by the spinner. You really need a standoff drive extension, and diverter cooling rings to direct air into the motor. Anyone seen a setup like this? It is not so bad with US radials, as they generally don'tuse spinners.

Generally if you need to stand off anything, you stand off the engine mounts, not the prop shaft. Easy enough to build a box behind the motor to mount the motor forward to, as opposed to getting the lathe out for a shaft extension. As for the cooling, i wouldn't sweat it so much. I run a 15" prop on my RMRC Anaconda, which is an inverted v-tail aircraft with an 81" wingspan.The motor is in a pusher config with an airscoop, but the Anaconda doesn't really fly fast like this might, so i'd suspect you'll have better cooling than you might imagine. I have yet to have any issues with engine overheating, even when being aggressive with the power for takeoffs.

Further, i'd probably not advise adding additional fan rings to the aircraft for cooling or scale. You'd most likely need to manufacture something yourself, and at that point may open yourself up to balance issues.

To answer some of the questions you mentioned in your first post:

Your powerplant for this aircraft will probably weigh 1.5kg. I have a bunch of powerplants the same size as you're thinking for a b-36 build that will happen eventually. The motors weigh 490g each, a 6s5a battery is almost on the dot 454g. By the time you factor in the retracts and servos, you're 1500g into the weight and have not touched a sheet of foam yet. That being said unless you're building a speed demon, acrobatic aircraft you plan to hover or a quadcopter, you won't need a >1:1 thrust to weight, and this might result in a cooler running motor anyways.

Retracts come in three flavors: Servo, Electric servoless and pneumatic. Servo uses a servo to move a pushrod that attaches to the landing gear block. A knuckle on the landing gear block locks the gear in a closed or open position, meaning your servo won't get damaged on a landing. Servoless is the same thing as servo in an all-in one package that runs off a screw and electric motor. Both of these are powered off your receiver battery or a similar five volt electrical system. Depending on your config, going with this option may warrant you setting up a separate 5v electrical system so your retracts dont overload and kill your BEC or drop your voltage so low your receiver browns out. Alternately is pneumatic where you take a can of compressed air up with you and a valve system sends air to a piston that operates the retracts. You can get a product called a "Gear sequencer" and use a 9g servo to actuate your gear doors. The sequencer will delay the door closing so the doors dont shut before the gear. That being said the FW190 only has a door over the lower part of the door, so you may be able to get away with a stick attached to the door that rubs against the wheel to close it.

You have this blend of "i want to make this scale" and "i want to make this my own" going on, i'd pick one and stick with it to be honest. If you want to design something brand new and scale as possible, it will sit in your shop for the next two years while you obsess over details. If you make it your own and don't obsess over details, you can fly in a month or two maybe, fly, crash, learn, and improve over time. You could also start off with a design someone else has made, like the pretty stellar looking FW190 Niez designed, add retracts and lipstick to that, and make the changes you want to in later revisions

https://forum.flitetest.com/index.php?threads/foamboard-focke-wulf-190.58325/

 

[OwenN]

That foamboard FW is pretty neat! I got the plans download. I will have a look!
That looks like a fairly easy build.

I will have a good read of your retracts info.
The Banggood integrated retracts are pretty cheap- $24 for a 19kg-cm unit.
No rods supplied-they look like they have a 5mm extension shaft. I would need a socket to pick that up.
A 3-4 kg model only needs 2mm (80 thou) piano wire legs.

I have to find what the hole sizes are in the 3.5 inch wheels. by DU-Bro.
-how do you hold those on? I used to wind fuse wire, and epoxy it in place.

Re: motor and props-a carbon sports 14x6 prop running at 9,000 and 16,000 rpm,
motor 6S 1000 KV -
kw = 1.8 input, 1.3 output, 24 v, 70 amps?- may not need this much if using 8500 rpm.

The prop could theoretically go to 19,700 rpm before hitting the speed of sound, but this would need a proper metal prop.
16,000 is the recommended limit for a carbon non-race prop.

Torque = 1.3 N - as opposed to 0.45 from the 2806.5 motor
The motor is twice the power, so should be about 8x the weight(cube ratio?)- 45g goes to 360 g?? . I will have a look.
I need benchmark tests on the motors to evaluate their output.
Also I need to work out thrust needed at the projected top speed, to get the high rpm torque datum.

These motors need tons of air at 1.8 kw- you want a blower inside the cowl if the motor is hard up against the spinner.

That is 66 mm, the same diameter as the motor, Generally, on a quad motor, the prop is hard against the bell. You want a
3/4 inch gap in there for cooling, or a water-cooled motor?
A big banger motor would likely not be a bell motor.
I don't know if you can get 14 inch prop quads??

I was thinking a "disguise" fan with a drive plate sandwiched behind the prop, but the centers are too small on available fans.

I could just have static angled flat blades, I suppose.
Any diverter flaps inside the cowl would also be static.

Maybe a lower kw motor and fan as a cooling blower- a 3 inch quad multi-blade, 200w or so?
It is tough to get enough cooling air from the front and divert it to the right place.

 

[OwenN]

I had a look at the plans. Now I need to watch a build video. That is not all that simple to put together.
Are all the skin panel patterns there? How do you get the wing aerofoil shape?
Where does the rear spar go?
How do you fit and drive the movable surfaces?
What do the "no peel" instructions mean?

If I made a 1: 7.5 scale model, it would be a bit bigger. I would like aerofoil-shaped fin and tailplane parts.
Not so easy in foam, but it makes a great fuselage!

Anyway, I have a giant balsa "thing" to draw up yet.
My present project: twin-prop canard-ish ducted fan (actually 3 wings-to get blowover of the rear elevons).

I haven't finished the 1/5 scale drawing yet, then I have full size layouts, and dozens of part patterns.
The good thing about foam, is that there are less parts!

Actually building a balsa plane is quick compared with drawing everything!
I would like an A0 Drawing board and drawing machine, but a little expensive, and hard to transport.
I will keep looking for a second-hand one in the nearest city. I can drive there.

Maybe $350 or so is not so bad-I just spent $230 on this rc-sound-board thing, and $114 on motors....
possibly next month?? - I can finish the 1/5 scale drawing and start on engine mounts/pod/prop ducts in the meantime.

 

[OwenN]

Whoops! Just lost my sense of humour! I will go and watch some more RC crash videos, for a laugh!
Hopefully I don't end up with a heap of splinters too often!

 

[OwenN]

Here is a finalised version of the FW190 Lavochkin modification. Dimensions included. The overall length remains the same, canopy tilted up at the back, nose cowl tapered by 1/2 inch . It should be easier to get the COG right. The original FW 190 uses a lot if wood in the rear planes, making then lighter. Effectively the wing is moved back a bit.

 

[OwenN]

I put the top fuselage profile back to a more tapered version. This is needed to assist airflow from the side cowl vents.
All the air has to go out there. There are no cowl flaps.

 

[OwenN]

Actually, I should go the whole hog and use the Lavochkin La 5 as the base layout, and tidy up its front cowl.
The tail is very similar to the P40, and the undercarriage is similar to the FW 190. The undercarriage legs look better proportioned than the FW 190.
It even has a nice looking wing plan profile.
I like the multi-part canopy, too. It is one of the better canopy shapes that is not a total bubble.

That upper front bump looks to be part of the compressor air intake, and the lower bump is a supplementary oil cooler?
Both can be removed in a model.
It has the same side engine air vents, and the fuselage looks slightly fatter, with more "elbow room" for the pilot.
Do those stripes on control surfaces mean that they are fabric covered?

 

[leaded50]

if your afraid of the cooling.. why dont just buy replacement fan/spinner for a ready-plane FW190? its some with different sizes on the market.

 

[leaded50]

all Lavochkin planes from the WW2 times, was skinned with wood at fuselage and wings. Controlsurfaces was sometimes with fabric

 

[OwenN]

if your afraid of the cooling.. why dont just buy replacement fan/spinner for a ready-plane FW190? its some with different sizes on the market.

Was this referring to the original 66 mm spinner and the single motor?

I now am planning stacked sets of 3 motors, which bring the engines out into the airflow. I couldn't find a motor that could even
spin a 9x5 at 16,000 rpm, get 95 mph, and give 2000 gf static thrust.

You would need a step-up gearbox to use anything on the market- high powered ones are 300KV-100KV.
That would be ok for a 30 inch prop...

I don't think any market fw190 versions match my scale or performance "wants".
(10m = 2.126m) about 1: 4.7 scale, 2kW power nominal, plus the rpm/torque limitations, to give 14000 rpm at full speed,
and 5 kgf static thrust, probably at 13,000 rpm? 14x6 prop)

If electric, that would be 3245 w at 1300 rpm, 14000 rpm indicates around 1100 KV 4S, and 13,000 at 72%,
or glow at 9,000 rpm, 1292 w That is a big glow engine.

2010 w, 2.6 hp, 9000 rpm.
That would be an OS Max 95, 0.949 cu ins-around 15cc-2.7 hp at 14,000 rpm, but not at 9000 rpm,
That is 1.6 of the speed so would need a 25cc glow motor at 9,000 rpm.
I would expect it to spin up to 14,000 in flight, making 4.4 HP. the .49 was limited to 15,000,
so a 14,000 rpm 25cc glow motor would be a race-tuned one! (normal 9,000 r and below)- that is for 30 inch props.

OS don't make big race engines, theirs are small ones about 3.5 cc, for rc cars.

 

[OwenN]

all Lavochkin planes from the WW2 times, was skinned with wood at fuselage and wings. Control surfaces was sometimes with fabric

The Hurricane had quite a bit of fabric , too, but wasn't that fast. - they won the Battle of Britain mainly by tactics and superior numbers.
No dogfighting, just dive, hit, and run!!

The FW 190 had tail surfaces skinned in ply.

The La was probably mostly ply, like the Mosquito-good wartime use of materials.

1700 hp and fabric control surfaces sounds a bit evil, though! that is a 400 mph plane!

 

[OwenN]

https://hobbystation.co.nz/fms-1400mm-focke-wulf-fw190-yellow-6-pnp/
interesting. 61 mph, 2550 kg, motor 4250 , 580KV, 4S
572 w (486 rated) 36A, 70max, 2850 static thrust at 6000 rpm.
$528 rtf, not in stock.

https://www.horizonhobby.com/produc....5m-bnf-basic-with-smart-combo/EFL01350C.html

I want one! unfortunately, they don't ship to New Zealand.- The ones you get from ali express
are 1250 or 1100 mm span, A 1400 (55 inch) would suit better, though.
They also have an La-7 and an FW TA-152 !!