F-19 Cowl Bumps

[Fjquast]

It has been awhile since I have checked in and hope everyone is doing well. The F- 19 just came out of annual and I have a few small items to focus on over the next year to keep it looking good.
1) Does anyone have a good place to purchase some cowl bumps?
2) I will also be looking for some engine mount rubber over the next year. Any advice or contacts would be appreciated!
3) Does anyone run Vortex Generators on their airplane? I'm curious what you think of them. They work well on a Chief we have and I was seeking some feedback on the TC as well.

https://www.emapa.aero/Taylorcraft-Micro-Vortex-Generators-p/taylorcraft.htm

https://www.aircraftspruce.com/catalog/appages/microvgkits11.php

I know crammed a few questions in a single post and I hope that doesn't deter anyone.

[Nefj40]

VG's, do it. They are a great add-on. The cowl bumps, if you have a decent one, just get some fiberglass and make some using the original one as a mold.

[PA1195]

I'd not fly the Taylorcraft's NACA 23012 airfoil without VG's if slow flight and steep turns were normal ops, especially when heavy. Load the wing and the stall gets more abrupt. The VG's smooth the pressure peak near the leading edge at high angle of attack and ultimately the stall behavior.

Helio Courier figured it out and added leading edge slats to that wing.

Gary

[Taylorcrafty]

I'd not fly the Taylorcraft's NACA 23012 airfoil without VG's if slow flight and steep turns were normal ops, especially when heavy. Load the wing and the stall gets more abrupt. The VG's smooth the pressure peak near the leading edge at high angle of attack and ultimately the stall behavior.

Helio Courier figured it out and added leading edge slats to that wing.

Gary

There is definitely more abrupt stall when heavily loaded. Can be useful for short landing, but can also be dangerous.

[Taylorcrafty]

It has been awhile since I have checked in and hope everyone is doing well. The F- 19 just came out of annual and I have a few small items to focus on over the next year to keep it looking good.
1) Does anyone have a good place to purchase some cowl bumps?
2) I will also be looking for some engine mount rubber over the next year. Any advice or contacts would be appreciated!
3) Does anyone run Vortex Generators on their airplane? I'm curious what you think of them. They work well on a Chief we have and I was seeking some feedback on the TC as well.

https://www.emapa.aero/Taylorcraft-Micro-Vortex-Generators-p/taylorcraft.htm

https://www.aircraftspruce.com/catalog/appages/microvgkits11.php

I know crammed a few questions in a single post and I hope that doesn't deter anyone.

1) Are these cowl bumps for the spark plugs or the C150 exhaust?
2) I got mine from Aircraft Spruce.

[astjp2]

Univair Carries a nice spark plug bump for the ercoupe

[Robert Lees]

I'd not fly the Taylorcraft's NACA 23012 airfoil without VG's if slow flight and steep turns were normal ops, especially when heavy. Load the wing and the stall gets more abrupt. The VG's smooth the pressure peak near the leading edge at high angle of attack and ultimately the stall behavior.

Helio Courier figured it out and added leading edge slats to that wing.

Gary

The NACA 23012 airfoil as fitted to our beloved Taylorcraft is also the same airfoil section fitted to (for example) the outboard sections of the DC3, and the whole section of various Beech designs including the so-called "Doctor-killer" Bonanza. It's a very efficient aerofoil, in terms of lift over drag. It's one of the reasons a Cub will be slower than a Taylorcraft on the same horsepower.

The 23012 airfoil has a wicked sudden stall characteristic, particularly at high wing loadings; fortunately for us, CG Taylor knew his stuff and used this section because of its efficiency. Also, because of our low wing loading (weight) and long span, the stall is very benign, with the appropriate use of rudder.

[PA1195]

I believe the VG's reduce that leading edge discontinuity Robert. This link at page 272 plus or minus describes the NACA 23012 airfoil and its behavior. Scroll down for a free look.

Gary

[Robert Lees]

I believe the VG's reduce that leading edge discontinuity Robert. This link at page 272 plus or minus describes the NACA 23012 airfoil and its behavior. Scroll down for a free look.

Gary

Indeed you are right Gary! But Vgs get in the way of washing chores, and I don't fly into such short strips in the UK where Vgs become important! If the wind is over 15kts, I just land into wind!
Take care; fly safe!

[n3328z]

I owned an F-19 & an F-21B years ago -- recently bought another F-19 with VGs --- not quite sure if I like them because the slower stall speed seems to make landings a bit more challenging than I remember with my non-VG TCrafts. 1) your nose/AOA needs to be higher during 3 point landings = more difficult to see over the nose. 2) you need to wait longer to let the tail down during a wheel landing so your directional control is limited to rudder and drum brakes. - David

[PA1195]

^^^^David, yes the VG's allow a % slower stall without a sharp break. Doing a falling leaf maneuver after stall becomes easier with the rudder. Having VG's under the horizontal stabilizer adds some elevator and trim tab authority. I added rubber elevator seals for a Pitts from Aircraft Spruce to add even more control at low airspeed and forward CG. But it took my effort to slow the plane more on landing to cope with the lower stall speed in ground effect.

One thing to consider is to remove a few of the VG's in front of the fuel tanks and maybe a bit more outboard. Micro left them off in that area in their original designs, mainly for Cubs and Champs with larger wing fuel tanks. Then they extended them to the wing root area and under the tail. Without VG's inboard that portion will stall earlier than the outboard wing. That may offset some of the floating effect.

Also confirm your wing washout is correct. Some have flatter wings that can change their slow speed behavior. I like 1.5 or more degrees of washout measured with a digital level wing root to last full outboard rib.

Gary

[astjp2]

Short mount and long mount affects the aoa too, short mount seem to be a higher aoa on 3 point

[PA1195]

Short mount and long mount affects the aoa too, short mount seem to be a higher aoa on 3 point

I wonder if that's the case if the CG location is the same for the two mounts on landing? For example, look at a turbine engine converted Beaver or Otter....the engine and prop are located way out in front of the wing to maintain the approved range of center of gravity. Moving the CG forward (like with the 4" longer mount vs short, or adding engine accessories or heavy prop), adds opposing download on the tail the wing then has to support to maintain desired AOA. Overall, wing loading increases with forward CG which can affect performance in all portions of flight.

If having landing issues with a forward CG add weight or move existing load to the aft baggage or tail. The whole point in moving the Model 19's engine forward to begin with was to provide more room for aft baggage. And Taylorcraft engineer Gilberti took it from there with his STC SA1-210.

Gary

[astjp2]

Probably, center of lift really doesn’t change, but I see in ground effect as influence the actual angle vs ground plane reference.

[PA1195]

Tim we know there's more involved than what I wrote. CG<->Center of Lift/Center of Pressure distance as AOA is changed for example. Then there's the moment arm between the short arm vs long arm mount and the CG that has to be offset by elevator movement, the rate of which can be felt. Different response time and pressure on the controls, etc.

In theory the VG's will allow the leading edge to fly at higher AOA, which moves the practical Cl/CP further forward.

David notes: "1) your nose/AOA needs to be higher during 3 point landings = more difficult to see over the nose. 2) you need to wait longer to let the tail down during a wheel landing so your directional control is limited to rudder and drum brakes. The plane needs to be slowed more with VG's to counteract the tendency to float on landing."

Tall tires make it even more of a challenge to see the runway. With 26" Airstreaks the runway ahead isn't visible except next to the plug bumps on my plane when 3-point.

Gary