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-   -   Speedbrakes on the RV-10 (https://vansairforce.net/community/showthread.php?t=154854)

Flandy10 12-20-2017 05:13 PM

I guess it's time for Paul Harvey.....
 
"and now, the rest of the story"

As Dan (who has flow in my airplane) has stated, speed and energy management---I get it. I fly all three of the A320 models for my day job.

My request was for information, which the first reply provided, the rest of you just assumed you knew better. I promised when I first posted that I would include the good and the bad. Well, this is one of the issues that I've been searching for an answer to and its a two fold problem.

First,---The prototype engine I have runs at 2200RPM inflight- ALL THE TIME. The MTV-9 is set up to absorb all 230HP at approx. 2150 rpm statically. Think about that for a second..................... have you figured it out yet? Answer-- The static thrust is significant!:eek: The Rv-10 is a slick airframe compared to the C182 that has used this type engine. When you compare my prop to the MTV-12, that any of you may be using, the blades are bigger. So slowing this thing down is more jet like. When power is reduced to idle, you coast for a while as the speed bleeds off. Planning is required for a stabilized approach.

Second----This is an air cooled diesel, if the CHTs get TOO COLD, the auto light function may not work and the pilot WILL start sweating. The lowest temps I've seen so far here in Georgia was 30F. It started first time using the glowplugs and didn't miss a beat inflight because the CHT never dropped below the min. inflight temp. Now, if you were flying in the high teens in MN in the winter and pulled it to idle and left it there--shock cooling may be the least of your worries.

The above two reasons are why I am interested in talking to someone who has installed the speedbrakes.

A little added drag in the pattern or when asked to expedite the descent by ATC would be a good thing. The production CD-265 is planned to operate at a different max rpm, so issue number one will be less of a problem. But the shock cooling and auto ignition will need to be watched.

I have flow this engine for 100 hours and have come to understand it. It's not a Lycoming- that's for certain. Even if my performance numbers don't eventually equal up to or exceed that of a 540 powered -10, that's fine with me.

I love the smell of Jet fuel in the morning.:D

Ron RV8 12-20-2017 07:25 PM

Had a set of Precise Flight brakes in the Mooney. At cruise power, popping the brakes would give me 1500fpm down right now... I would reduce that to about 1000fpm with trim for ear comfort...

Haven't missed them on the -8 except perhaps when coming into a formation a bit hot.

I realize you are considering other factors so I hope this helps...

dmaib 12-20-2017 07:38 PM

Quote:

Originally Posted by Flandy10 (Post 1226922)
"and now, the rest of the story"

As Dan (who has flow in my airplane) has stated, speed and energy management---I get it. I fly all three of the A320 models for my day job.

My request was for information, which the first reply provided, the rest of you just assumed you knew better. I promised when I first posted that I would include the good and the bad. Well, this is one of the issues that I've been searching for an answer to and its a two fold problem.

First,---The prototype engine I have runs at 2200RPM inflight- ALL THE TIME. The MTV-9 is set up to absorb all 230HP at approx. 2150 rpm statically. Think about that for a second..................... have you figured it out yet? Answer-- The static thrust is significant!:eek: The Rv-10 is a slick airframe compared to the C182 that has used this type engine. When you compare my prop to the MTV-12, that any of you may be using, the blades are bigger. So slowing this thing down is more jet like. When power is reduced to idle, you coast for a while as the speed bleeds off. Planning is required for a stabilized approach.

Second----This is an air cooled diesel, if the CHTs get TOO COLD, the auto light function may not work and the pilot WILL start sweating. The lowest temps I've seen so far here in Georgia was 30F. It started first time using the glowplugs and didn't miss a beat inflight because the CHT never dropped below the min. inflight temp. Now, if you were flying in the high teens in MN in the winter and pulled it to idle and left it there--shock cooling may be the least of your worries.

The above two reasons are why I am interested in talking to someone who has installed the speedbrakes.

A little added drag in the pattern or when asked to expedite the descent by ATC would be a good thing. The production CD-265 is planned to operate at a different max rpm, so issue number one will be less of a problem. But the shock cooling and auto ignition will need to be watched.

I have flow this engine for 100 hours and have come to understand it. It's not a Lycoming- that's for certain. Even if my performance numbers don't eventually equal up to or exceed that of a 540 powered -10, that's fine with me.

I love the smell of Jet fuel in the morning.:D

Well, now that you 'splain it that way...................................! An interesting and complex problem.

bruceflys 12-21-2017 06:48 AM

Another Experience
 
I have speed brakes on a Cessna P210, which adds about 500 fpm to descent rate or subtracts about 15 KT from level speed. As noted above, on a cleaner and lighter airframe such as a Mooney [or RV-10], speed brakes will provide more effect. When deployed they produce a rumble and vibration, enough to be noticed, but not to the point of disturbing passengers.

woxofswa 12-21-2017 02:00 PM

It just seems to me that the holy grail of the impressive effort that you have put forth in this project is a CAFE level quest for efficiency and speed brakes to efficiency are like a mustache drawn on a masterpiece.
Have you considered cowl flaps that are restrictive in the closed position or adjustable (butterfly?) intake air?

rvbuilder2002 12-21-2017 02:36 PM

Quote:

Originally Posted by Flandy10 (Post 1226922)
"and now, the rest of the story"

As Dan (who has flow in my airplane) has stated, speed and energy management---I get it. I fly all three of the A320 models for my day job.

My request was for information, which the first reply provided, the rest of you just assumed you knew better. I promised when I first posted that I would include the good and the bad. Well, this is one of the issues that I've been searching for an answer to and its a two fold problem.

First,---The prototype engine I have runs at 2200RPM inflight- ALL THE TIME. The MTV-9 is set up to absorb all 230HP at approx. 2150 rpm statically. Think about that for a second..................... have you figured it out yet? Answer-- The static thrust is significant!:eek: The Rv-10 is a slick airframe compared to the C182 that has used this type engine. When you compare my prop to the MTV-12, that any of you may be using, the blades are bigger. So slowing this thing down is more jet like. When power is reduced to idle, you coast for a while as the speed bleeds off. Planning is required for a stabilized approach.

Second----This is an air cooled diesel, if the CHTs get TOO COLD, the auto light function may not work and the pilot WILL start sweating. The lowest temps I've seen so far here in Georgia was 30F. It started first time using the glowplugs and didn't miss a beat inflight because the CHT never dropped below the min. inflight temp. Now, if you were flying in the high teens in MN in the winter and pulled it to idle and left it there--shock cooling may be the least of your worries.

The above two reasons are why I am interested in talking to someone who has installed the speedbrakes.

A little added drag in the pattern or when asked to expedite the descent by ATC would be a good thing. The production CD-265 is planned to operate at a different max rpm, so issue number one will be less of a problem. But the shock cooling and auto ignition will need to be watched.

I have flow this engine for 100 hours and have come to understand it. It's not a Lycoming- that's for certain. Even if my performance numbers don't eventually equal up to or exceed that of a 540 powered -10, that's fine with me.

I love the smell of Jet fuel in the morning.:D

I am wondering to myself if a custom designed belly board wouldn't be a better option than speed brakes.
Depending on its design it could be more variable than the all or nothing speed brakes, which might make it more useful for your situation, but not sure.....

vic syracuse 12-21-2017 02:50 PM

I was wondering that controlling the air inlets might be easier and less draggy. I'm not an aeronautical engineer and I didn't stay at a Holiday Inn last night, though. :)

Low Pass 12-21-2017 03:58 PM

Be prepared for spontaneous human combustion and instant death!

Flandy10 12-21-2017 08:40 PM

Rodrigo, Ron and Bruce- Thanks, that is the type of info I wanted.

While speedbrakes may not be an artistic solution, they are a readily available option that would accommodate both issues. The cowling now includes a set of cowl flaps that I use every flight and I am working on "shrinking the exit" to keep the temperatures in the desired range during all phases of flight.

I have also considered, as Scott mentioned, a "belly board" similar to the SBD dive brakes. Still contemplating the structural and operational implementation of that idea.

This project is constantly evolving and there are days I wish I was an areo engineer who stayed at a Holiday Inn Express. I can truly say that this project has been an education.

bruceflys 12-22-2017 05:45 AM

Long EZ Speed Brake
 
Some Long EZs have a belly air brake. See: http://www.aryjglantz.com/2013/08/ch...-overview.html for some starter ideas.


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