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Speedbrakes on the RV-10

Flandy10

Well Known Member
In years past, RD&D made a kit that installed speedbrakes manufactured by Precise Flight for the RV-10. I know a few were installed as I've seen pictures on several for sale ads.

I would like to talk to anyone who installed them on their RV-10 or purchased a set and never installed them.

Please send me a PM.
 
In years past, RD&D made a kit that installed speedbrakes manufactured by Precise Flight for the RV-10. I know a few were installed as I've seen pictures on several for sale ads.

I would like to talk to anyone who installed them on their RV-10 or purchased a set and never installed them.

Please send me a PM.

Replying here instead so it's findable by anyone else who may be interested in the future (but feel free to PM me if you have anything that may not be useful to others).

I would be in the latter group - I purchased them, was eager to install, realized what would really be involved, and ended up returning them.

They seemed to be great products, but do not come with any bracket or even suggestions on how to install in an experimental - at most they shared the instructions for some certified aircraft (e.g. Mooneys, Cessnas) to serve as inspiration.

On the 10, it'd only fit between one specific pair of ribs on the wing, and even then it'd require some surgery on the wing to get installed - cutting a big hole on top, making some custom doublers that would be riveted together with the ribs, making a bottom-skin support for it, adding a water drain hole, etc.

The real issue was when I calculated the force that would be required from the ribs and skin onto the brakes at Vne to keep it from "twisting back" (and ripping out part of the wing) - just thing of the drag force being applied on the top half of the brakes, and how that creates a moment on the piece as a whole - at that point it became clear that it was a major structural change and I just wasn't comfortable doing it anymore.

Another deciding factor was talking to a few people at Airventure about propellers - it seemed to be a consensus that you can get similar braking action from the MT prop at the high RPM setting.
 
Not sure why anyone would feel the need to add speedbrakes on a 10. I've got 200+hrs on my 10 now and there hasn't been a single minute IFR or VFR where they would have been useful to slow down or lose altitude, and this includes "screaming" down the ILS 7 at KORL at 160KTS until GS capture at the controllers request to maintain best forward speed. Slowed down and stabilized at 120 KTS just like that. IMO this would definitely be a mod not worth the cost, time, and effort to install YMMV......

Note: My execution of the ILS mentioned above is most atypical for me. 99% of the time I stabilize my speed at the IAF or on VTF at 120 KTS (I used to do it at 90 but based upon other's procedures tried 120 and liked it better). Occasionally, at the controllers request I'll maintain faster if the conditions are right, as there were at the time I shot that ILS (well briefed approach, smooth air, no on-board equipment issues, etc). If they hadn't been right, I'd have stated that I all I could give 'em was 120 and that would have been that.
 
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Just because you can does not mean you should.

I am with the post above, although rather than 200 hours we have 1500, same result. Energy management 101 is a class many should take that contemplate them for a -10. A Lancer maybe, but even then I would say, a lot I know don't have them either and get by without all the drama.

My $0.22 worth.:)
 
Come on guys, skip the 'learn to fly" lecture. Scott's RV-10 is not like yours, he understands speed management, and he has a reason for asking.
 
Many years ago I was offered a pair. I didn't do it. 1300 hours on it and I don't see a real need for them.
 
Please read Dans post above— none of these comments address Scott’s simple request.
 
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I am soundly in the not needed camp. I get that a TDI is different, but the primary reason for exploring TDI is energy efficiency and speed brakes are the kinetic energy equivalent of a fuel dump valve. What we retain in value from burning fuel is speed and altitude.
If shock cooling is an issue, it doesn’t seem much more complicated to me to devise and install some form of variable air intake (reverse cowl flaps) than speed brakes which just dump energy (money) overboard.
 
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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
 
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...
 
"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.
 
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.
 
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?
 
"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.....
 
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. :)
 
Be prepared for spontaneous human combustion and instant death!
 
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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.
 
Come on guys, skip the 'learn to fly" lecture. Scott's RV-10 is not like yours, he understands speed management, and he has a reason for asking.

Well maybe in future he should articulate that. :confused::mad::cool:

Not everyone is a mind reader.
 
Perhaps an analogy; we have a few readers old enough to have flown the early turbojets. Recall that many of those airplanes deployed drag devices for the approach, with the specific goal of enabling a higher power setting while flying a descent.

This photo illustrates a similar aspect of flight management with the 200-series diesel. Here Scott is turning base for KFFC's R31, elevation 807 ft. Remember, he cannot dip below 30" MP, or allow CHT below 212F.

2wpqoee.jpg


Can't chop and drop (minimal prop braking, and it's already near minimum power anyway). Can't push the nose down (the RV-10 is slicker than a Skylane). To make a normal pattern size work in KFFC's traffic, Scott started descent at midfield; we're at 700 AGL in the downwind to base turn. He keeps it nailed dead on 500 FPM with the speed creeping back, all the way to the flare. On the runway, CHT is a little less than 230. No problem for a pro.

The catch? This was a 70F day in Atlanta. Consider a 0F day in Chicago or Calgary. Given the OAT, it's going to be hard to fly an approach at the required 45" MP.

It's not a problem. it's just an engineering task, developmental work to match an airframe to an engine.
 
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If you like I can expand a bit on the characteristics of the Precise Flight brakes I had on the Mooney. YMMV on the -10...

They came with the plane and I quite liked them. When I looked at them for the -8 I could not justify the additional cost and figured I could add them later if I really missed the functionality. You really want to keep your diesel warm, so another "tool" in your kit would be useful...

Sorry but I never really made note of speed change in level flight as I was usually throttling back as well or joining up with someone else and not really looking inside. The button was right beside the throttle so I did not have to look for it. I do miss them for that function and end up reducing power a lot more to compensate...

As I said before, at cruise power, popping the brakes gave 1500fpm down instantly.

Having one brake stick up was a "non event", happened only a couple of times on landing due to pre-takeoff water which had frozen.

Taking off or making a go around with the brakes accidentally extended was also a "non event". Eventually you notice the drag as you try to accelerate and slap yourself on the forehead... Not even noticeable on initial climb out...

It was explained to me that the brakes were far enough back on the wing to have little affect at low speeds and high angles of attack, thus the small impact when landing and taking off...

The brakes on the Mooney had been installed by a previous owner and did not look too difficult.

They were deployable at any speed. Nice when you're cresting a mountain ridge or even just getting down to flap speed...

Overall I was impressed with their product and was always amazed at how effective those little blades were at cruise speed... If I had a need I would not hesitate to install them again, but so far with the -8 I'm happy without...

Hope this helps...
 
Perhaps an analogy; we have a few readers old enough to have flown the early turbojets. Recall that many of those airplanes deployed drag devices for the approach, with the specific goal of enabling a higher power setting while flying a descent.

This photo illustrates a similar aspect of flight management with the 200-series diesel. Here Scott is turning base for KFFC's R31, elevation 807 ft. Remember, he cannot dip below 30" MP, or allow CHT below 212F.

2wpqoee.jpg


Can't chop and drop (minimal prop braking, and it's already near minimum power anyway). Can't push the nose down (the RV-10 is slicker than a Skylane). To make a normal pattern size work in KFFC's traffic, Scott started descent at midfield; we're at 700 AGL in the downwind to base turn. He keeps it nailed dead on 500 FPM with the speed creeping back, all the way to the flare. On the runway, CHT is a little less than 230. No problem for a pro.

The catch? This was a 70F day in Atlanta. Consider a 0F day in Chicago or Calgary. Given the OAT, it's going to be hard to fly an approach at the required 45" MP.

It's not a problem. it's just an engineering task, developmental work to match an airframe to an engine.

Today's high bypass turbofans all have high idle thrust. Some have a "flight idle" mode triggered by flap extension. Primary reason is to meet Part 25 requirements for an 8 second limit from idle to go around thrust. The 787 is a model of efficiency - and yet it has speedbrakes to assist with energy management, as do all of the Boeings and Airbuses. The use of speedbrakes is often necessary and not an indictment of the pilot's skills.

If I recall correctly from articles published years ago when Cessna was flight testing the SMA diesel on the 182, one of the issues was low power descents and their effect on engine temperatures. The diesels on the Diamonds (Thielert/Continental/Austro) have operational limitations too and they are liquid cooled.

So Scott's request for information on speedbrakes seems perfectly logical to me.
 
Yep

"...The use of speedbrakes is often necessary and not an indictment of the pilot's skills..."

You would be surprised at the number of people I work with that do not understand this point...

It always cracks me up when they refuse to use everything available because of a perceived deficiency in their skills...
 
In the spirit of the learning value of discussion, I would like to further expound.
I’ve flown airliners with speed brakes for almost 30 years. Yes airliners have to have them and there are certain situations, usually (but not always) attributed to sloppy controller and/or pilot work where they are necessary. They are also necessary to meet requirements for emergency descents. (Something not a player in the RV world). I’ve flown with crewmembers who use them every leg and others who might deploy them once or twice over a four day sequence. I tend to fall in the latter category.

It all boils down to physics and chemistry. A pound of fuel contains a certain quantity of chemical energy. Burning that fuel to convert the energy within creates positives and negatives. The positives are stored reserves of energy in the form of speed and altitude, and the negatives are wasted and useless heat.

All airplanes are compromises as energy converters. Mine has A/C. I have electively chosen to trade a cost, weight, drag, and engine power tap in exchange for being comfortable in the Arizona summer and having a happy wife.
My goal for my airplane was just a comfortable cruiser.

I’m not going to presuppose why someone else built their airplane the way they did. Having said that, if I were going to build a TDI 10 (something I considered), the defining goal of the project would be EFFICIENCY. Trying to get the ship from Point A to point B on the fewest fuel calories consumed. A passionate quest for that almighty SFC that blows the others away. That in my opinion is what justifies the extra time, money, and hassle, over simply hanging a Lycoming. Someone else’s goals may be entirely different.
Refining the holy efficiency quest goes back to the previous stored reserves of speed and altitude that we extract from our investment of fuel and wringing them out to the fullest return. Speed brakes, by design are an antithesis to that quest. They take the positive energy bought and paid for and dump it overboard trashing the SFC charts, and in my mind, the whole purpose of the conversion. I dont mean to be argumentative or disrespectful. I am actually in awe of what has been accomplished so far. Nevertheless, One schmoes’s opinion would be to look for a less wasteful solution.
Good luck and best wishes.
 
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Discussion

So in light of your post, how do you usually fly cross country in your -10?

I am not flying yet, so I am curious. Some guys, in search of that "efficiency" attempt to find the sweet spot between speed and fuel efficiency...others seem to open her up and let her run.

What is your technique?
 
So in light of your post, how do you usually fly cross country in your -10?

I am not flying yet, so I am curious. Some guys, in search of that "efficiency" attempt to find the sweet spot between speed and fuel efficiency...others seem to open her up and let her run.

What is your technique?

Can't speak for Myron, but I fly between 8000 and 10000 (I don't have O2), WOT, leaned to 11.5 gph, 2350 RPM which usually nets me 160 KTS TAS. More often then not I'm also close to or at my GW of 2700lbs.
 
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