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Extending lower cowl slot - how much is too much?

JackinMichigan

Well Known Member
We have an RV-10 with a 3-blade prop. We had to extend the nose wheel slot several inches to make installing the lower cowl even possible, but even then it's still a difficult 2-man job that requires removal of the spinner.

Another RV-10 builder suggested extending the slot even more and then adding a removable plate to cover the slot forward of the nose wheel stalk. Extending the slot would definitely make this job easier, but how much is too much? I certainly don't want to impair the structural integrity of anything. Also, is adding a cover plate necessary? It seems to me that the extra slot length would allow more air to flow into the engine compartment, which I'm thinking is good.

P.S. - Airworthiness certificate issued yesterday. It's only a matter of days till the first flight.
 
We have an RV-10 with a 3-blade prop. We had to extend the nose wheel slot several inches to make installing the lower cowl even possible, but even then it's still a difficult 2-man job that requires removal of the spinner.

Another RV-10 builder suggested extending the slot even more and then adding a removable plate to cover the slot forward of the nose wheel stalk. Extending the slot would definitely make this job easier, but how much is too much? I certainly don't want to impair the structural integrity of anything. Also, is adding a cover plate necessary? It seems to me that the extra slot length would allow more air to flow into the engine compartment, which I'm thinking is good.

P.S. - Airworthiness certificate issued yesterday. It's only a matter of days till the first flight.

That is what I did. I did not like the thought of the now separated fiberglass bouncing around. I added a .032? aluminum plate with nutplates on the inside (easy to install from the outside) to cover the slot forward of the gear leg. Keep a good gap between the gear leg fairing and the plate.

I found that on real hot days leaving the plate out added a bit of engine cooling. For those days I use a single short piece of .063? angle (with nutplates) that goes across the gap toward the rear - the rest is left open.

Carl
 
Gear Leg Slot

It's important to consider the effect of the enlarged slot on engine cooling in various flight attitudes. In cruise, the exposed slot may indeed add cooling capacity, but it's not needed and just presents unnecessary cooling drag. On the other hand, on takeoff and climb, cooling demand is highest, but the slot, now presented at a relatively higher angle of attack to the airstream, actually reduces the pressure differential between the top and bottom cowl and provides less cooling. Answer: make the slot as long as you like but fill it in with a plate if you want to preserve the efficient cooling capacity already designed in.
 
That is what I did. I did not like the thought of the now separated fiberglass bouncing around. I added a .032? aluminum plate with nutplates on the inside (easy to install from the outside) to cover the slot forward of the gear leg. Keep a good gap between the gear leg fairing and the plate
Carl

I did the same. I also kept the piece of fiberglass matrix that I cut out of the cowl, and glued it to that plate, just for appearances.
 
Anything’s got to be better than having to have two people, and removing the spinner to get that bottom cowl off. Know your question related to the slot in front of the nose wheel but two things that will be of great help with cowl removing are............. cut a six or seven inch slot in one of the brides good towels to fit over the propeller to engine connection, slide both sides down behind and in between the spinner and top and bottom cowls, the bits that hang below the spinner can be gaffer taped to the spinner, now both top and bottom cowls can be removed without damaging that award winning paint job. .....Second, consider fitting a airintake snorkel as described in VAF 11-01-2017 RV10 forum, the ability to remove that connection between fab box and cowl before fitting the cowls basically means the bottom cowl only needs to clear the firewall piano hinges before it can be lowered to clear the spinner. Cheers from Western Australia
 
Was considering pro sealing some overlapping baffle seal material to close the gap but still allow the slot for removal, has anyone done that?
 
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