How do you attach your cowl?

[Chris Walby]

As the title suggests could forum members please post pictures/words on the various methods of attaching engine cowls (doesn't have to be just plastic/glass fibre).

Hopefully this will be useful to future builder as reference options.

Starting off with:

• long servo screw rubber backed washer - mixed results
• Captive nut, m3 screw and rubber backed washer - nice but a it tricky installing (any tip/tricks?)
• keyhole drop and lock with screw

Anyone used Nylon screws?

Mush be loads of other ways?

[Frank Skilbeck]

Is this for IC or Electric? on electric I've used magnets with alignment pins on a couple of models, works very well. I can't claim any credit for this though as I first came across in on the Chris Williams designed ASK11 motor glider.

[Ace]

3 or 4mm nylon cheesehead screws into tapped basewood blocks with the threads hardened with CA. Being nylon in wood doesn't vibrate loose (not on my IC 4*'s anyway) nor dose the nylon chew the cowl.

You could dab the heads with humbrol for a colour match if required.

[Trevor]

For a wooden cowl over an electric motor - cowl locates on cocktail sticks and secured by strips of matching covering. Or sometimes the motor can be mounted from the rear (access via the battery hatch) in which case there is no need for a detachable cowl at all.

[leccyflyer]

For plastic or fibreglass cowls, typically four or five small self tappers into the firewall, around the periphery. If the sides are balsa then I've sometimes inserted hard points from yellow Sullivan snake inners to screw those self tappers into. Metal cowls and larger heavier fibreglass items use larger self tappers into small blocks of hardwood engine bearer epoxied to the face of the firewall.

As they are all electric I've not found the need for any vibration-resistant grommets.

[Murat Kece 1]

I use self-tapping screws tapped into firewall or wood/plastic inserts, sometimes in combination with magnets. Occasionally I use plastic washers/gaskets.

Edited By Murat Kece 1 on 23/12/2020 09:14:15

[Peter Miller]

I use keyhole slots in the rear cowl former.These slide over screws in the firewall. Just slide the cowl up about 3/16" of an inch and it comes off.You need a latch at the bottom to stop it sliding up in flight although that is not too serious, it just looks untidy.

[Eric Robson]

This is a tip from Richard Wills, I don't know about i.c but on electric a few dabs of silicane sealer will hold it firm without having to use screws.

[Chris Walby]

Thanks guys, very helpful and keep he ideas coming, cheers

[Brian Cooper]

Fit rubber grommets to the cowl and secure with self-tappers.

[philip pember]

as Eric above said, silicon, mastic better or if wood on wood no more nails, if need to remove just slice down gap with scalpal.

[Broken Prop]

For IC: Self tappers into hardwood,blocks on the firewall as others have stated. However I oversize the holes in the hardwood blocks and insert short lengths of fuel tubing into the holes, with a bit of CA. The screws bite into the tubing but retain some flexibilty against vibration.

I also cut a small washer from fuel tubing and fit it under the head of the self tapper to improve the flexibility.

[Martin McIntosh]

All too complex. For anything up to and including 50cc petrol I always use the grey plastic right angled brackets with two holes drilled on one side. These are fixed to the firewall with two No.2 self tappers, then after careful measurement one of these is added through from the outside for each. Drill the cowl 2mm and the bracket 1.6mm. By going into plastic they never vibrate out unlike screwing into ply. If one gets stripped due to over tightening it can always be replaced with the next size up. Just about to do a cowl fixing but could not get the correct ones so shall try an inferior variety. You can always make your own from some L shaped ABS.