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Flap extension speeds for the Rocket.

Gt-401

Active Member
I?ve got about 150 hrs on my new to me rocket since I got it a little over a year ago. I have been flying it with the same flap extension speed as the RV-4. Now that I am flying it IFR more and more, I am wondering if anyone has beefed up the flaps to allow for a higher extension speed. It sure would be nice if I could get approach flaps in at 100 or even 120 KTAS
 
Flaps are the only control surfaces that get extended into the airstream and stay there. All other control surfaces extend into the airstream only momentarily. Flaps carry some pretty extreme loads. I wouldn't try expanding on the designer's limits without doing some extensive engineering.
 
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it's OK

You can drop the flaps about an inch at 120KIAS - just look at flap speeds on a C210 or similar - certain speeds are OK for various angles. Same applies here.

If you have the Rube Goldberg setup under the floor, you might need to change to the F1/RV8 style system to keep things from bending...that short length of 1/4" threaded rod might not survive, along with the actuator rods.
 
I removed the Rube Goldberg mess under the floor and went with an RV-8 style primarily to address the poor geometry. In the process I reduced complexity and weight and as a bonus the existing linear actuator is now capable of exerting more force at the flap attachment points without bending or stalling. The Rocket flaps are smaller and have closer rib pitch than RV-4, so should be stiffer in torsion. All that said I have no idea where the LIMFAC is on this system but I've busted published limits from time to time without damage.
 
Is there a weak link built in?

Is there an intensional weak spot in the flap mechanism that is meant to bend or shear to keep from damaging more important parts, like for example a clutch on the motor, or maybe a breaker that would pop if to high a load was applied to the flaps? Leading to my next question, is the flap motor powerful enough to bend stuff if it is active at too high a speed?
 
My opinion is the weak point in the flap system is the torsional load on the main tube in the flap weldment. I believe the main tube would bend before anything breaks.

That said, I redesigned and implemented a "rube goldberg" flap drive completely hidden under the floor. "out of sight, out of mind."

The goal was to have no holes open in the floorboards which allow smoke and cold air to come in, and be easily accessible for maintenance.

I'd venture to guess its at least 3x more rigid than the stock RV-4/rocket setup. There are four spherical bushings supporting the main tube. The mechanical advantage of the linear actuator is also improved.

Titanium components were fabricated to keep the weight down.

If interested I can post a video of it in operation.
 
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...If interested I can post a video of it in operation.

Post a link, please!

The "Rube Goldberg" aspect of the original design include (IMHO): transmitting a high load through 90 degrees of change using high friction nylon pillow blocks; a walking beam that has such poor bearing support that the linear actuator needs a nylon sliding support to keep the whole mess from carving an arc through the aluminum on the bottom of the fuselage; poor mechanical advantage on the too small torque tube; heavy, solid rod linkage in several places; and using stud mounted heim joints at the flaps instead of spacers and through bolts.

Other than that, its a great system!
 
Yours is not to question...

I’ve got about 150 hrs on my new to me rocket since I got it a little over a year ago. I have been flying it with the same flap extension speed as the RV-4. Now that I am flying it IFR more and more, I am wondering if anyone has beefed up the flaps to allow for a higher extension speed. It sure would be nice if I could get approach flaps in at 100 or even 120 KTAS

First answer: WHY? My manual flaps on my HR2 were extended at either half or full or "pilot's choice" by pressing the button and pulling slightly.
You might try your prop in a flatter pitch, different power setting and be happy with it.
As mentioned by Mel, Flaps get enough abuse as it is...adhere to the RV4 max extension speeds and they will last a long time...
V/R
Smokey
 
I personally would feel more comfortable flying an ILS at 120kts with half flaps especially if you may be picking up ice. So I can see his reasoning.
 
Hmmm... re-designing a flap system so that you can fly an *?unstabilized approach? in KNOWN icing conditions ?- seems problematic to me.

*flying an approach at 120K in an airplane that is designed to land at 60K is, by definition, an unstabilized approach.

I?m not saying you shouldnt fly an approach at the upper limit of the speed that defines your stabilized approach criteria in order to maintain more precise controllability - with a clean wing, but why do you need flaps for that?

If you encounter unforcast icing that you think requires you to use flaps on an approach at 120K, then go ahead and do it. If built according to plans, the flaps should be able to withstand a load 50% above design on a limited basis, but this is an abnormal/emergency situation. I don?t think I would chose to do that, but if you get the airplane on the ground without damage or injury, you?ve succeeded. However - if you haven?t experienced impact icing on the bottom of your wing, accentuated by using flaps, you won?t want to do that twice, ask me how I know....
 
No flap approach.

It sounds like there is a lot of room for improvement in the flap system, but maybe the simplest way to handle the problem is to come up with a no flap approach procedure. Leaving the flaps up until I get into visual conditions or going missed. The only thing that concerns me about that is when I arrive at minimums going 100 or faster it will eat up a bunch of runway getting the rocket slowed down. I probably just need to shoot some practice approaches and see what speed works best.
 
It sounds like there is a lot of room for improvement in the flap system, but maybe the simplest way to handle the problem is to come up with a no flap approach procedure. Leaving the flaps up until I get into visual conditions or going missed. The only thing that concerns me about that is when I arrive at minimums going 100 or faster it will eat up a bunch of runway getting the rocket slowed down. I probably just need to shoot some practice approaches and see what speed works best.

I?ve been a professional pilot for 31 years, 20 in the AF and 11 at the airline. About a a mile or 2 prior to glide slope intercept or the FAF I?m at 80 knots with half flaps. A minor tweak at that point to start down and then nothing to do until decision height except look for the approach lights and the runway. Is it slow? Yes, but I?m flying an airplane without a flight director, autopilot, and another pilot next to me, that likes to get knocked around by the wind a lot.

That said, I do regularly practice ILS?s no flap at various speeds in day, VMC conditions. When duty calls, I?ll be ready.
 
It sounds like there is a lot of room for improvement in the flap system, but maybe the simplest way to handle the problem is to come up with a no flap approach procedure. Leaving the flaps up until I get into visual conditions or going missed. The only thing that concerns me about that is when I arrive at minimums going 100 or faster it will eat up a bunch of runway getting the rocket slowed down. I probably just need to shoot some practice approaches and see what speed works best.

Rockets loose speed really easy. The big fan on the front is more effective than any speed brake you will ever encounter. Just pull off the power and if that does not slow you fast enough, holding the nose up and a touch of rudder cross up will.

Smokey said it just about right in an earlier post.
In any case after you fly your machine VFR for a while I think it will become a non issue to slow your rocket with ease. They are heavy pigs and slow down a lot easier than a 4 does. Just pull power.

The weldment of the flap arms to the bell- crank torque tube is the weak link and the actuator arm to the same torque tube. Ask yourself what would happen if one of the flap arm tubes broke off the torque tube from overload/overspeed in IMC what the result would be. There is no need to ever go there.
 
I’ve been a professional pilot for 31 years, 20 in the AF and 11 at the airline. About a a mile or 2 prior to glide slope intercept or the FAF I’m at 80 knots with half flaps. A minor tweak at that point to start down and then nothing to do until decision height except look for the approach lights and the runway. Is it slow? Yes, but I’m flying an airplane without a flight director, autopilot, and another pilot next to me, that likes to get knocked around by the wind a lot.

That said, I do regularly practice ILS’s no flap at various speeds in day, VMC conditions. When duty calls, I’ll be ready.

My SOP is to pull the power back and slow down to 100 MPH approaching GS intercept and add 10* of flaps. I find that it is easier to control things at that speed. Further down the approach (500 AGL) I will slow down to 85. I hand fly all of my approaches and find the additional speed makes it easier to manage turbulence induced challenges.

Might want to try it during a practice to see if it helps.

Larry
 
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Rocket Bob!!!!

Clever flap gizmo made of unobtanium but that?s not the story!!

You have wings on that thing!! You?ve been holding out:)

Good show, can?t wait till you get to fly it.

Cheers
HR
 
Thanks gents. I?ve been working on it at a glacial pace. Too many projects! Its one of a kind for sure.
 
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Old airplane

New airplane

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Engine

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Flap actuator

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Having fun with pictures
Enjoy
HR
 
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Rockets loose speed really easy. The big fan on the front is more effective than any speed brake you will ever encounter. Just pull off the power and if that does not slow you fast enough, holding the nose up and a touch of rudder cross up will.

Smokey said it just about right in an earlier post.
In any case after you fly your machine VFR for a while I think it will become a non issue to slow your rocket with ease. They are heavy pigs and slow down a lot easier than a 4 does. Just pull power.

The weldment of the flap arms to the bell- crank torque tube is the weak link and the actuator arm to the same torque tube. Ask yourself what would happen if one of the flap arm tubes broke off the torque tube from overload/overspeed in IMC what the result would be. There is no need to ever go there.

The design of the F1 flap system is different than a RV, but here's a data point. A guy oversped his flaps in a F1 Rocket a few years ago and the bolt securing the torque tube to the flap motor broke, abruptly retracting both flaps. That's a lot better outcome than one flap retracting with the other remaining extended, and he was lucky. I don't think anyone could depend on that happening a second time.
 
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It’s a fun thread we can drift. Grant Semanske in Seattle (he builds Jeff Lavelle’s Reno package). Dave Bectold did the CF layups, he’s built over 30 Glasairs. 30! He’s the Art Chard of Glasairs. Retired from Boeing with tons of 787 experience. It’s a TIO540AE2A twin turbo with larger turbos and intercoolers too. Plenum top is CF too. Cowling CF, belly panel, seats, on and on CF. That stuff itches way more than eglass. Use lotion to keep fibers out of your skin pores, no itching.
 
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cool. I met Jeff last year while visiting with friends at Payne field in Seattle and had an hour-long conversation with him over his go-fast twin-turbo setup. Your engine looked familiar.
 
Grant learned a bunch on that setup, this one is a little prettier, both are very functional. This has all the internal and external A/I. Jeff would have crushed at Reno this year but nose gear doors didn’t close all the way. Smoked engine pushing 90 + inches of boost.

Back on rocket topic

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It was designed that way:

The design of the F1 flap system is different than a RV, but here's a data point. A guy oversped his flaps in a F1 Rocket a few years ago and the bolt securing the torque tube to the flap motor broke, abruptly retracting both flaps. That's a lot better outcome than one flap retracting with the other remaining extended, and he was lucky. I don't think anyone could depend on that happening a second time.

To be specific, Mark is talking about the Evo system, not the Sport wing system. The Evo system has AN3 bolts attaching the drive arm, and both actuator arms, to a central torque tube. The design was to have a single weak point (drive arm thru-bolt) that would fail if the pilot over-sped the system. Turns out it worked. It took a ~20KT overspeed with full flaps, and engine at full power, to get it to fail, but the failure caused no problems.

This system will allow the operator to drop about 1? of flap at 140KIAS to slow down, as required. 1/2 flap is available at 120KIAS; full flap at 100KIAS. Keep in mind the Evo flaps are the Fowler type, so the drag and lift numbers are different when compared the the plain type on the Sport wing.
 
I have been out in the Rocket a couple of times this past week, and I had a chance to fly a couple of LPV approaches with the flaps up, and it seems to work just fine to start down the glide slope at about 15 inches and 120 kts. Then level off at the minimums, with throttle to idle, and put in full flaps as soon as it slows to 85, and land. It wants to touch down at about the 1500 ft mark..

I like this approach procedure for two reasons, 1 it keeps the flaps up and makes the missed approach simpler, and 2. It keeps me from worrying about over speeding the flaps on the way down the glideslope.
 
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