Cowl Flap Control

[Nev]

When selecting a panel vernier control for cowl flap, do I need a control similar to the Throttle/Mixture/Pitch, or is a control similar to that used for a heater sufficient? I’ve got one of each in the picture below and there’s a definite size difference where panel space is a premium.

[TimTall]

I'm wondering the same thing. I worry that the heater control won't be strong enough but I'm not sure. I'm planning on using the ACS A1600 SERIES POSITIVE LOCK CONTROLS - DUAL END unless someone can share a better option. The panel has changed a bit since I took the photo but the four full size controls - throttle, mixture, prop, cowl flap - fit nicely between the screens.
2020 11 16.jpg

[Nev]

Good to see your panel layout. My reason for considering smaller “knobs” particularly for the cowl flaps is I’m concerned about the spacing between the controls. I’ve also got two screens, which leaves 2 inches/50mm between the 4 controls. But I’d prefer more as it’s pretty tight. I think 2 1/2 inches is closer to standard.

[JimParker256]

If you decide you really need to have cowl flaps (see Mark G's post below), one possible space-making solution would be to move the cowl flap control over the left of the EFIS, lined up horizontally with the throttle, etc. You've got a "blank" area there. You could even fit a "T-handle" type there, with the "rotate-to-lock" mechanism.

[Nev]

PS Here’s a link to vernier controls in the Vans store, prices seem quite attractive.

[Bcone1381]

I have no experience controlling cowl flaps in a Bearhawk. I'm going back to memories from the 1980's.....Small knobs with a locking mechanisms were used.

I think the C-310 had something like a twist to lock T-handle. I seem to recall that the airflow over the cowl door would move the cable. Just leaving it unlocked was interesting, as it would find its own position and it was about right. The cable required some force to move the door out of their Faired position, then a twist of the T handle would lock it in position. I think a push-button knob would work too. T-handle would take up more panel real estate than the push button small knob.

Reference Aircraft Spruce Catalog p.151 A-770 Button Lock Dash Control.

[Mark Goldberg]

Just a quick comment on installing cowl flaps in your four place: My Bearhawk has almost 1,900 hours of flying. Mostly in Texas where summers are HOT. Never needed cowl flaps as all my temps are fine after some fine tuning at the beginning.

This posting is for builders who might get the impression that cowl flaps are required / must have items. For me that has not been the case. I have flown with cowl flaps on certified planes in the past, and understand their benefit.

Install cowl flaps if you want. It is your choice as a builder. No problem. But for my plane with a 540 cowl flaps have never been required to have acceptable temps. Mark

[robcaldwell]

Just a quick comment on installing cowl flaps in your four place: My Bearhawk has almost 1,900 hours of flying. Mostly in Texas where summers are HOT. Never needed cowl flaps as all my temps are fine after some fine tuning at the beginning.

This posting is for builders who might get the impression that cowl flaps are required / must have items. For me that has not been the case. I have flown with cowl flaps on certified planes in the past, and understand their benefit.

Install cowl flaps if you want. It is your choice as a builder. No problem. But for my plane with a 540 cowl flaps have never been required to have acceptable temps. Mark

Mark, you and I discussed cowl flaps a while back. You mentioned that increasing the size of the outlet at the tunnel should increase airflow for improved CHT's. That's what I plan to do in the event I cannot manage my CHT's.

[rodsmith]

I'm wondering the same thing. I worry that the heater control won't be strong enough but I'm not sure. I'm planning on using the ACS A1600 SERIES POSITIVE LOCK CONTROLS - DUAL END unless someone can share a better option. The panel has changed a bit since I took the photo but the four full size controls - throttle, mixture, prop, cowl flap - fit nicely between the screens.
2020 11 16.jpg

Your control layout is way too close together, will make it hard to operate the controls. Same thing was pointed out to me and I had to cut out and replace the sub panel with new spacing of 2 1/2" center to center.

[TimTall]

That's not exactly to scale. The final spacing is a little over 2 1/8". Same spacing as on the plane I currently fly. I moved the Parking brake so there's a little more room to spread out.

[Battson]

When selecting a panel vernier control for cowl flap, do I need a control similar to the Throttle/Mixture/Pitch, or is a control similar to that used for a heater sufficient? I’ve got one of each in the picture below and there’s a definite size difference where panel space is a premium.

The one which they've used in ZK-RJE was really nice, better than mine. I think it's the newer push/pull cowl flap control with a button lock, coloured white so clearly designed for the purpose (as one option).

It was something like this, however not as old-school. It looked like a more modern molded high-strength plastic control knob.
https://www.aircraftspruce.com/pages...acontrols2.php

I'm wondering the same thing. I worry that the heater control won't be strong enough but I'm not sure. I'm planning on using the ACS A1600 SERIES POSITIVE LOCK CONTROLS - DUAL END unless someone can share a better option. The panel has changed a bit since I took the photo but the four full size controls - throttle, mixture, prop, cowl flap - fit nicely between the screens.

There is a huge amount of force on the cowl flaps in a dive, or with the prop at full power. I doubt a button-lock control would be sufficient.

I am pretty sure I have the A1600 control.
It has worked fine - although the mechanisim is wearing out a little after 800hrs of use. I liked the Cessna styles, both old and new, better.

I would say, you do want the control kinda in-front of you. Reaching across the cockpit and trying to push it open mid-dive is not easy. You need to push in a straight line to avoid stressing the assembly and wearing it out. In turbulence it's a bother.
You also want to have the control attached to something more solid than the panel, the steel superstructure is best. The panel flexes under the stresses of opening and closing the flaps, especially if you aren't pushing straight through - in my case, this flexing has cracked my transponder's plastic surround.

[TimTall]

I ended up removing the two individual tabs that were on my cross tube at the bottom of the panel and adding a wider steel tab. All 4 of the push/pull controls will go through the panel and the tab so there will be minimal flex.

[Battson]

Your control layout is way too close together, will make it hard to operate the controls. Same thing was pointed out to me and I had to cut out and replace the sub panel with new spacing of 2 1/2" center to center.

Throttle needs a full fist of clearance, otherwise it would be really annoying. Same for cowl flaps.
The Vernier controls, I would say they can be close together IMHO. It's pretty rare you use them with a full fist. Normally just a small turn, or a delicate thumb and two/three fingers in a pinching position.
Aesthetically, I went for equal spacing between knobs. But I ended up with the mixture knob and especially cowl flaps knob too far away. This is something I often think about changing / fixing.

[Gerhard Rieger]

I used a lockable throttle vernier and put it in the left next to my park brake cable.