Model IV smooth cowl

[Av8r3400]

Does anyone out there have a model IV with the smooth cowl? I am considering this on my project plane but would like to see some photos of what one of these looks like and how the visibility over the nose changes (or doesn't) with this difference.

[Geowitz]

In my albums there are a bunch of pics. Let me know if you need more.

There's definitely more room and I like the look better. My Kitfox reminds me of a mini Cessna 185. Visibility is better as the top slopes down to the thrust line which is the same as the round cowl.

* Also, in the "Engine" forum there are some closer pics on the "HKS 700T" thread.

[Av8r3400]

I knew there had to be someone out here with one. Thanks! :D

What was confusing me was/is the bump on the top of the SS cowl for the gearbox. I didn't know if this was also on the III/IV smooth cowl. The yellow plane below must be a IV with a 912 and the two part smooth cowl (note the belly radiator) where the blue and white plane is the later model (SS?) four part cowl with the radiator inside the cowl.

Which motor are you using?

Thanks again.

http://kitfoxaircraft.com/images/Web%20Gallery/img/KAphotogallery%20%2837%29.jpg


http://kitfoxaircraft.com/images/Web%20Gallery/img/KAphotogallery%20%2886%29.jpg

[Geowitz]

One more thing - The top half of the firewall is different than the round cowl. It has more of a shoulder than a rounded top. This makes the windshield fit a little different also, but not too hard to adjust. I just got a scrap sheet of stainless from our local ornamental metal shop to cut a new one from.

[Av8r3400]

I'm not concerned about the firewall because I need to build a complete new one. The one that was on my project looked like swiss cheese... :(

My project is basically a total rebuild, not just a recover.

http://www.teamkitfox.com/Forums/picture.php?albumid=116&pictureid=2505

[Geowitz]

Yeah, the second pic is an SS. The bump on the model IV cowl isn't toally neccessary for the gearbox clearance. More of a visual/style thing because it doesn't get as narrow as the SS does at the tip of the nose of the cowl. In other words it has more height at the front/hub.

I am using the HKS 700T. My thread in the engine forum will be following my progress. Starting on the engine mount this weekend.

[Av8r3400]

I just was looking at the 700T thread (http://www.teamkitfox.com/Forums/showthread.php?t=2995) and it took me a minute to realize that was your installation. Sorry, here's my sign... :o

[dholly]

Larry-

This is Ron Seyffer's model 4 w/ 912ul and smooth cowl. I think the smooth cowl looks great and offers much improved visibility, particularly with a TD. Unless you're totally enamored with the round cowl look, I would do it. Actually, I'm looking for a KF 5-6 smooth cowl myself right now. :)

Doug

[cubtractor]

Here is a pic of my Model IV that I just finished rebuilding with a smooth cowling. Hope it helps

[DanB]

Here is a pic of my Model IV that I just finished rebuilding with a smooth cowling. Hope it helps

She looks very clean Mike. I like the yellow w/ black...nice contrasting with the jury strut.
Dan

[ackselle]

I'm doing the same thing as Av8r3400.... considering the conversion to a smooth cowl on an IV..... Is there anyone out there that has done a conversion and can speak to any:
1) challenges in the conversion (fit, changes etc.)
2) performance differences (cruise, top speed)

Cheers,
Ackselle

[Av8r3400]

One thing I just learned from talking to Deb while at Airventure: the conversion requires a different motor mount.

That could be a game changer for me... :(

[ackselle]

Hmmmmmm.....ditto for me. That may be a clue as to the lack of replies to the conversion difference question.

Well...change of plans.... I'm thinking we may need to fabricate our own!

[cubtractor]

I changed cowls during my rebuild but I am running a Jab 2200 so it was an easy transition. Can't help with the speed though as I never flew it with the round cowl.

[herman pahls]

I would like to revive a dormant 6 year old thread regarding model 4's and smooth cowls to see if there is any current info..
I could call Debbie at Kitfox for details regarding the needed parts but want to know if the visibility significantly improves on the model 4 since it is a shorter cowl fore-aft than the model 5's and up with smooth cowls?

I was at the 2018 High Sierra and saw Trent Palmers new smooth cowl and one of his friends has a yellow model 4 with a smooth cowl.

Someone mentioned a new motor mount.
Does the new mount raise or lower the engine.
The cowl is ~$1000, how much is the motor mount?
Any other major changes like the exhaust or relocating the oil tank.
I realize the firewall will need to be changed.
Does the radiator end up in the cowl like the 5-7's?


Please share any new info..
Thanks
Herman

[cubtractor]

Herman,

I mounted the radiator flat in the bottom of the cowl so the air has to exit over the radiator as it exits the cowl. My smooth cowl didn't have enough room to mount the radiator like the model 5-7's. I had to open up the bottom of the cowl to do this. Otherwise, I think you would have to mount the radiator similar to conventional Model IV mounting. There is a picture in my album where you can see the radiator mounting.

[Geowitz]

Visibility with the smooth cowl doesn't seem much different to me on the ground compared to the round... still have to look out the side and S turn. Maybe better on approach, but by the time I pull back to a 3 point attitude or even for wheel landings, my eyes are out the corner of the windshield (for better depth perception in my opinion) or side windows anyways even if it has theoretically better visibility.



Basically same opinion as Cubtractor on the radiator. Could be wrong, but I don't think it's big enough without modification for the radiator and on a model 4 I also believe the initial design is for it to still be on the belly. My HKS 700T is air cooled, but I do have an intercooler that is similar in size to the Rotax radiator. I modified the bottom of my cowl and stretched it for the room I needed.



As far as I can tell the thrust line is the same for both cowlings. If I had to guess I would say that the mount is probably mostly the same or could be modified to work since the thrust line is the same. Fore and aft may be slightly different, but I would be surprised if it was. I f I had to guess at the difference, it may be that the smooth mount has a provision for radiator mounting and perhaps it does fit in the cowling?


Firewall changes are just the top half and exhaust is what it is - you cut a hole for the pipe.

[Av8r3400]

Scott Palmer's plane (Formerly DesertFox4 - Steve's) is a model IV smooth cowl. The engine mount is totally different and not interchangeable without modifications to the firewall.


Scott's (Steve's) plane has a modified instrument panel, but the standard instrument panel is the same between the two cowls and this is where your visibility is restricted. Changing the cowl alone will not improve your forward visibility.





My log term (5-year) goal is still to rework the firewall forward on my IV to include a smooth cowl and Rotax ring mount system similar to the new model planes. This will probably mean a boot cowl and engine cowl like the newer models. When I get to this project, I will document the process thoroughly.

[Geowitz]

How is the engine mount totally different and not interchangeable?... We keep hearing this but no one can say how. As long as the thrust line is the same, which I'm pretty sure it is and the length is adjusted what does the mount matter to the cowling?

[Av8r3400]

That is what I was told by Debra McBean. I will defer to her knowledge of the subject.

I believe the length of the mount is shorter, necessitating recessing the oil tank into the firewall. I can not confirm or deny that the thrust line is the same.

[rv9ralph]

I will speculate.

With the smooth cowl, the oil tank moves on the side, the intakes and carbs are back to their original inboard position. The moving of the oil tank requires a different mount.

Not sure but seems reasonable.

Ralph

[Esser]

My buddy has a smooth IV his oil tank is in the centre and low recessed intonthe firewall

[DesertFox4]

My model 4 did have the shorter oil tank and yes it was recessed into the center
and high up on the firewall. The intake manifolds had to be reversed from side to side due to location of the engine mount arms. There was no room under that cowling for the oil tank to be mounted on either side like the newer models do. That would have been nice as oil changes would be much much easier. Also there really was no room for mounting a radiator inside that cowl. Mine had to go underneath the fuselage. Forward visibility during flight was better than the bump cowl as the smooth cowl tapered down from the windshield to the spinner and also from the doors forward towards the spinner. My model 4 was always a tri- gear before I sold it to Scott. I would like to fly it as he has it set up now and see how it feels compared to the tri- gear.

[Av8r3400]

I will speculate.

With the smooth cowl, the oil tank moves on the side, the intakes and carbs are back to their original inboard position. The moving of the oil tank requires a different mount.

Not sure but seems reasonable.

Ralph


On the later model 5 through the current plane, this is true.



The smooth cowl 4 and early 5, the tank is behind the engine.

[kmach]

The model 5 Outback, smooth cowl, with the 912 dynafocal egine mount, the oil tank is slightly left of middle and at rear of the engine.


I believe the model 6 is the same.



I think somewhere in the 7 series and newer, the fixed boot cowl and the Rotax 912 engine ring mount came to be used, which got the carb manifolds back to stock orientation, put the oil tank on the side, coolant and oil radiator together slung underneath, plus gave a little more room to work on things, I think it moved the prop flange around 4" out from the firewall.

[HighWing]

I think somewhere in the 7 series and newer, the fixed boot cowl and the Rotax 912 engine ring mount came to be used, which got the carb manifolds back to stock orientation, put the oil tank on the side, coolant and oil radiator together slung underneath, plus gave a little more room to work on things, I think it moved the prop flange around 4" out from the firewall.

I agree with this assessment. On my new Model IV, I made my own engine mount moving the engine forward about 2.5" I was then able to put the oil tank on the passenger side low. A side note: Moving the engine forward was intended to return the baggage capacity to the 40 lbs. in the IV specs as I had a lot of fairings to close gap seals in both elevator and rudder. That far back, a couple of Oz. equals close to a couple of lbs. up front.

[herman pahls]

I appreciate all your responses.
I have been flying round cowl Kitfoxs for 23 years so visibility is not the issue as much as I like the smooth cowl look.
Improved visibility would be a bonus.
What I have learned from you guys is that the cowl alone will not improve visibility, the panel and glare shield need to be lowered also.
Hopefully I will run into Scott Palmers Kitfox to get a visual on what the recessed oil tank into the fire wall looks like and lowered panel and glare shield.
Does Desert Fox have any photos?
My current oil tank is centered high on the firewall behind the engine.
Apparently the required motor mount change required recessing the tank into the firewall.
I do not want a longer motor mount as Highwing did for CG reasons.
The big question, is the cost and effort worth the make over?

[DesertFox4]

Herman, I may have some original build photos from 2002 however I am away from home for a couple weeks.
I like to be look of both cowls so it would not be worth all the effort in my humble opinion. You would likely have to trim your firewall and there may be a real possibility that you would need a brand new one to cut it to the new shape of the smooth cowling’s unique contours. My model 4 has a one piece firewall. It was also extra long underneath the fuselage for more fire protection and a little more puncture resistance if you had set down in trees or rocks etc.

[Hoenshell]

I'm in the middle of converting a IV round cowl over to a smooth cowl and just to add what I am discovering. The engine mounts look identical except for the oil tank mounting brackets that are separate on my new smooth cowl engine mount (black) and are welded on the round cowl engine mount (red). I also purchased the upper firewall and a new windshield since it was already cut out for the round cowling.
https://image.ibb.co/idLTSq/IMG-4547.jpg
https://image.ibb.co/fLDRDV/IMG-4548.jpg

[Geowitz]

Really not trying to be annoying :p, but yup... Looks the same and easily adaptable as I suspected. I'm sure there are other differences within the rest of the conversion, but that looks totally adaptable.