B Model Flap Question
Posted: Mon Jun 14, 2021 10:44 am
by pappas
(Saturday I posted this question in the classified section in error)
I have 100 hours on my Waiex B Turbo now. I’m finally getting down to the last few items that were low on the priority list.
I noticed that my stall speed in the landing config was not down in the forty-something MPH range and thought I should finally get to looking at it. Measuring with a digital level, here is what I found:
With flaps full up at 0 degrees deflection, the top of the flap leading edge just kisses the aft edge of the top wing skin. The flap can not retract any higher.
I was not able to achieve the recommended 2 29/32 inch distance between the leading edge aft skin lip and a straight edge laid across the flap and upper wing skin. I have about 3 3/16 inches. This seems to me that the flap trailing edge must be slightly lower than build specs at full up. I don’t notice any ill effect.
However, when I activate the Sonex electric flap motor through its entire range of motion and to maximum down flap, the motor’s range of motion is only capable of deflecting the flaps to 23 degrees down. I am not achieving 30 degrees down flap. I’m guessing that the 7 or so additional degrees may make the difference in lowering the stall speed into the forties.
Has anyone else found that the Sonex flap motor does not have the range of travel to fully deflect the flap to 30 degrees down? If yes, any solution? I did not have this issue with the manual flaps on my Legacy Waiex.
I figured that I could move the point where the flap motor attaches to the torque tube drive arm, closer to the torque tube. That would achieve greater torque tube rotation and flap deflection without needing more travel from the flap motor. But it seems to me that Sonex should have already figured this out and their angles should be right.
Of course, it is Saturday, so I will ask here and send an email to Kerry to read on Monday.
Re: B Model Flap Question
Posted: Tue Jun 15, 2021 12:40 pm
by pappas
Turns out that I mounted the flap hinges onto the lower wing skin too far forward. I had shoved them against the spar to guaranty that they were straight. However, that had the effect of restricting the top leading edge of the flap from coming forward all the way and causing the trailing edge to be too low.
Moving the hinges aft a bit from the rear spar changes the geometry enough to allow the flap to reside in the full-up position, reducing my 3 1/4 inch rigging measurement to the 2 29/32 inch neutral dimension required. So, it looks like I gained the additional down flap by raising the neutral point.
All my fault…Again! Thanks, Kerry for the confirmation.
Re: B Model Flap Question
Posted: Wed Jun 16, 2021 9:27 pm
by pappas
Can anyone tell me what was the final, eye-to-eye, length you have on your B model Flap pushrod? The one between the flap torque tube and the flap attach point. I am redoing mine and my plans show a 3-inch length of threaded 1/4 x 28 threaded rod. With the MW-4 Aurora female heim joints attached, the overall length is way too long.
It would be nice to see what you’ all have.
Re: B Model Flap Question
Posted: Fri Aug 06, 2021 7:57 pm
by T41pilot
I’m in the process of rigging my flaps right now. I’ve got one flap close now but it doesn’t look like I will achieve 30 degrees full flap deflection either. I ended cutting about an inch off the threaded rods and ended up in the neighborhood of about 4 1/4 end to end on the rod end bearings (not eye to eye). I took one measurement so far and ended up between 23 and 24 degrees full deflection. The small tweaking I have left might yield another couple degrees but I’m guessing that’s about it. Did you finally achieve the 30 degrees?
Re: B Model Flap Question
Posted: Wed Aug 11, 2021 4:59 pm
by pappas
Gregg,
Sorry, I just saw your response. Actually, I flew today for the first time in a month. It is hard to get motivated in Phoenix at 110 degrees. Today was only 85, but humid.
Anyway, I finished re-rigging my flaps, test flew it today for an hour, and the changes made an 8 - 10 mph reduction in my stall speed. Based on the “SaavyAnalysis” interpretation of my Dynon BlackBox data download, my stall is now occurring at 43 mph IAS.
The final measurement turned out to be 27 deg down flap from the baseline 0 deg measurement. I now have 2 29/32 inch measurements at the rear edge of the leading edge per flap rigging plan page.
Re: B Model Flap Question
Posted: Wed Aug 11, 2021 5:12 pm
by pappas
BTW, my serial # is WXB-0010. This is the first B model that Sonex shipped to a customer. I was reading the service bulletins and notice that Sonex has replaced the original electric flap actuator with a different model.
The changes are that the new actuator has a built-in position monitor which eliminates the need to buy and install a Ray Allen POS-12 and fab the brackets necessary to get a flap position readout on the instrument panel or EFIS. This certainly saves some steps in the build if you want to electronically monitor your flap positions. I like it.
It seems that the replacement actuator has a slightly longer throw than the original. Because of that, the plans have been changed to mount the new actuator higher on the crossover tube so it does not contact the fuselage floor under the baggage compartment. The upper mounting brackets and placement are also different from the original B model plans.
I think that the amount of travel is slightly greater on the newer actuator. If so, the additional throw might actually get that last few degrees of down flap.
Does anyone with a recent B model kit know who makes the new flap actuator with the position sensor? Images?
Re: B Model Flap Question
Posted: Wed Aug 11, 2021 6:05 pm
by T41pilot
pappas wrote:Gregg,
Sorry, I just saw your response. Actually, I flew today for the first time in a month. It is hard to get motivated in Phoenix at 110 degrees. Today was only 85, but humid.
Anyway, I finished re-rigging my flaps, test flew it today for an hour, and the changes made an 8 - 10 mph reduction in my stall speed. Based on the “SaavyAnalysis” interpretation of my Dynon BlackBox data download, my stall is now occurring at 46 mph IAS.
The final measurement turned out to be 27 deg down flap from the baseline 0 deg measurement. I now have 2 29/32 inch measurements at the rear edge of the leading edge per flap rigging plan page.
I got my rigging done on the flaps and was able to achieve between 27 and 28 degrees of full down deflection using the 2 29/32 dimension. I’m going to call that good. I have the old servo motor as well but rigged a DIY electronic solution for my flap position indicator and sensor that cost 25 bucks or less. Can be viewed in the Sonex group in Facebook.
Re: B Model Flap Question
Posted: Wed Aug 11, 2021 10:07 pm
by pappas
I recently had a conversation with Kerry. He said that27-29 is common. He had about that on his build. I wouldn’t mind a few extra degrees. Slow is cool!
Re: B Model Flap Question
Posted: Thu Aug 12, 2021 11:48 am
by XenosN42
[quote="pappas"Based on the “SaavyAnalysis” interpretation of my Dynon BlackBox data download, my stall is now occurring at 46 mph IAS. [/quote]
Check out the Flight Data Viewer. It’s a great way to analyze and store the blackbox data from Dynon devices. http://www.JASFlyer.COM
Re: B Model Flap Question
Posted: Thu Aug 12, 2021 2:11 pm
by pappas
Yeah, the MGL Flight Data Viewer looks good too. The biggest difference is that SaavyAnalysis has a free version and the FDV is $49.00. Not a bad price, but I do seem to like free!
Re: B Model Flap Question
Posted: Mon Aug 16, 2021 11:27 am
by pappas
(I have the old servo motor as well but rigged a DIY electronic solution for my flap position indicator and sensor that cost 25 bucks or less. Can be viewed in the Sonex group in Facebook.)
Gregg, I am not on Facebook, can you post the details of your DIY position indicator here?
Never mind, I found it. You electronics guys have all the fun. I have no clue how to make that thing!
Re: B Model Flap Question
Posted: Sun Sep 05, 2021 12:48 am
by Spaceman
What size fuse or breaker are you guys using on your flap motor circuit?
I initially had a 5a fuse installed (I don’t really remember how I chose that), and before I installed the wings and flaps I could run the motor up and down until it stopped moving (or slips its internal clutch or whatever it does at the end of its travel). Anyway, once I started rigging the flaps I found that it would pop the 5a fuse right as I hit the upper end of the flaps’ travel, and that was before I had really started setting them to the neutral position as called out in the plans. Nothing was binding , but maybe it was just hitting a little bit of friction right at the top. I switched to a 7.5a fuse, and then I could run the motor to the upper stop again without popping it.
Then I started actually setting the pushrods up, and I found that if I set the flap at that specified neutral measurement (74mm or whatever it is in english…), it would still sometimes pop the fuse right at the top when I raised the flaps. Again I can’t feel any binding if I move them by hand so it must just be a tiny bit of friction right at the top.
I lengthened both pushrods one turn from there and now it works great, I’m just not quite at the specified measurement. From what I can tell with my digital level they’re about 0.5 degrees down from where the plans want them. Should I try a 10a fuse or just stop worrying about it?! It’s wired with 18 gauge wires and it’s not a very long run…
Also, just for another data point, my pushrods were also way too long with 3" threaded rod. I cut them to 2" and now they’re good but both ends are screwed pretty much all the way in. 1-7/8" probably would have been perfect for me.
From full up to all the way down my flaps appear to move 27 degrees too. That’s probably good enough and I don’t know what I could reasonably do to get more travel anyway so I’m not too worried about that!
Re: B Model Flap Question
Posted: Sun Sep 05, 2021 12:52 am
by Spaceman
Here’s what my travel looks like by the way!
Re: B Model Flap Question
Posted: Sun Sep 05, 2021 10:50 am
by T41pilot
I have a 5 amp breaker for my flaps with no issues so far. They were run several times during the rigging process. I don’t linger on the switch at all when it gets to the end of travel in either direction. Under normal circumstances I would have chosen the value by looking at the model of actuator and looking up max current draw under load and then went above that by 1.5 or 2 times the value. I can’t remember if I actually did that or not. 10 amps is a lot of current and I wouldn’t expect the actuator to be using that much. If you can, find the actuator model and manufacturer and look up the specs. It’s been too long since I installed it to remember. My plane is closed up now, so I can’t easily find that for you without removing my seat back. Let us know what you find in case I need to change my breaker too.
Re: B Model Flap Question
Posted: Sun Sep 05, 2021 11:32 am
by pappas
I have a Vertical Power VPX Sport handling all of my electrical systems fusing and power routing tasks. It is adjustable and I can set any amperage I want for the components. I set my flap fuse limit at 7.5.
I set flap presets at 10, 20, and 30 (actually 27 degrees, I don’t think anyone gets the full 30 with the actuators we have). I touch the stick-mounted switch once for each next downward stop and the actuator will go directly to the selected stop. One touch upward, and the flaps go all the way up to zero.
The VPX allows me to limit travel, (an adjustable setting), to a final up and a final down stop. However, I can control my flaps without presets from my EFIS, similar to a panel-mounted switch. I noticed that if I hold the manual switch for too long at the top or bottom of travel, the fuse will pop. I think that is what is happening to you. In an effort to make sure that the flaps are all the way up or all the way down, you may be holding the switch a little too long which overloads the circuit and blows the fuse.
I also noticed in your video that if your initial digital reading is 2 degrees and your final reading is 27 deg, you may only have 25 degrees of down flap. I used the same digital level to set mine up. As long as the dirty stall turns out to be in the 44-46 mph range you are probably ok.
I also noticed that the plans called for a 3-inch pushrod. No, way too long! I think the plans are wrong. Mine is almost the same as yours.
Remember that if you have more than 2 and 29/32 inches distance above the leading edge as a flaps neutral starting point, that will mean that your flaps trailing edge is actually hanging down a bit into the airstream. Like flying with 2, or so, degrees of down flaps all the time. It took me a while to get that right but it made a big difference for me in the air. Less than 2 29/32’s and you will have reflexed flaps). I tried reflexing the flaps for better cruise. It gave me next to nothing in speed and made the stall speed higher.
Re: B Model Flap Question
Posted: Sun Sep 05, 2021 2:23 pm
by Spaceman
Gotcha, thanks for the info gents. Yeah I try not to excessively run the motor once it hits its stop, but when I was popping fuses it would pop instantaneously… so like the only way to not pop it was to stop short, which I don’t think would be practical for flight haha! Now that I have the 7.5a fuse in it seems to be working fine; I think I will stick with that. Yeah 10a seemed like a bit much to me, and if I was just brute forcing the flaps to the top of their travel anyway that didn’t really seem like the right answer.
The vertical power setup sounds awesome. Mine isn’t anything as fancy as that, but I put a position sensor on the actuator so I can see on my G3X screen where the flaps are at least. I still have to manually control the switch.
Lou, the 2 on the level at the start of the video is 0.2 degrees… I zeroed it on the flap but it went from 0.0 to 0.2 when I sat in the seat. So I guess I have 26.9 degrees of travel really!
I did some more messing around today and also rigged the left flap. Oddly the left flap only travels about 25 degrees even though everything is the same between the two of them as far as I can tell. I’m not sure if 2 degrees difference with full flaps will be noticeable in flight. I guess I’ll find out! In the C-130 if the flaps break and go asymmetric we don’t get any notice until they hit 7 degrees difference, and that’s not too dramatic. Probably not a valid comparison though haha
Anyway, I investigated more why I can’t get my flaps in exactly the right ‘up’ position. As far as I can tell they’re each about 0.3 degrees down from where they’re supposed to be. I might try filing a tiny bit off the upper trailing edge of the wing to make some clearance, but I think I’ll save it for later. I also found it pretty tricky and inconsistent to measure anyway, so I might just be measuring it poorly.
For reference, on the ground my upper longerons are at 8.4 degrees, and the top of the flaps are at 20.0 degrees when all the way up. So relative to the plane, the top surface of the flaps slope downward at 11.6 degrees. Maybe they should be 12? That’s a heck of a lot easier to measure in my opinion!!
Re: B Model Flap Question
Posted: Sun Sep 05, 2021 10:13 pm
by pappas
Oh yeah, 0.2 makes more sense. My flaps are not exactly the same either. However, I don’t feel any effect unless I am going too fast for the flap angle I have deployed. Full flaps at 60 mph or less and I don’t feel any adverse effect. Full flaps at 100 and I get a distinct heavy left wing.
Re: B Model Flap Question
Posted: Sun Sep 05, 2021 11:29 pm
by Spaceman
Makes sense!
Re: B Model Flap Question
Posted: Mon Jul 25, 2022 9:25 pm
by pfhoeycfi
pappas wrote:Turns out that I mounted the flap hinges onto the lower wing skin too far forward. I had shoved them against the spar to guaranty that they were straight. However, that had the effect of restricting the top leading edge of the flap from coming forward all the way and causing the trailing edge to be too low.
Moving the hinges aft a bit from the rear spar changes the geometry enough to allow the flap to reside in the full-up position, reducing my 3 1/4 inch rigging measurement to the 2 29/32 inch neutral dimension required. So, it looks like I gained the additional down flap by raising the neutral point.
All my fault…Again! Thanks, Kerry for the confirmation.
Same happened to me…I have 3 1/4 inch and my hinges were located as per the plans. I’ll have to drill out all the rivets and move the hinges slightly aft. Do you recall how much you actually moved your hinges? I suspect it will be trial and error. I should have delayed riveting the wing side of the flap hinge until after rigging …
Re: B Model Flap Question
Posted: Tue Jul 26, 2022 10:32 am
by pappas
Peter,
I don’t remember the distance that I moved the flap hinge aft of the lower rear wing spar. I do remember that the spec is in the plans and I set it to the plan measurement. It made all the difference.
Re: B Model Flap Question
Posted: Tue Jul 26, 2022 12:35 pm
by pfhoeycfi
pappas wrote:Peter,
I don’t remember the distance that I moved the flap hinge aft of the lower rear wing spar. I do remember that the spec is in the plans and I set it to the plan measurement. It made all the difference.
Ok thanks. I did a calc and moving the hinge back about 1/32" should do the trick…
Re: B Model Flap Question
Posted: Fri Aug 05, 2022 4:44 pm
by pfhoeycfi
Spaceman wrote:Gotcha, thanks for the info gents. Yeah I try not to excessively run the motor once it hits its stop, but when I was popping fuses it would pop instantaneously… so like the only way to not pop it was to stop short, which I don’t think would be practical for flight haha! Now that I have the 7.5a fuse in it seems to be working fine; I think I will stick with that. Yeah 10a seemed like a bit much to me, and if I was just brute forcing the flaps to the top of their travel anyway that didn’t really seem like the right answer.
The vertical power setup sounds awesome. Mine isn’t anything as fancy as that, but I put a position sensor on the actuator so I can see on my G3X screen where the flaps are at least. I still have to manually control the switch.
Lou, the 2 on the level at the start of the video is 0.2 degrees… I zeroed it on the flap but it went from 0.0 to 0.2 when I sat in the seat. So I guess I have 26.9 degrees of travel really!
I did some more messing around today and also rigged the left flap. Oddly the left flap only travels about 25 degrees even though everything is the same between the two of them as far as I can tell. I’m not sure if 2 degrees difference with full flaps will be noticeable in flight. I guess I’ll find out! In the C-130 if the flaps break and go asymmetric we don’t get any notice until they hit 7 degrees difference, and that’s not too dramatic. Probably not a valid comparison though haha
Anyway, I investigated more why I can’t get my flaps in exactly the right ‘up’ position. As far as I can tell they’re each about 0.3 degrees down from where they’re supposed to be. I might try filing a tiny bit off the upper trailing edge of the wing to make some clearance, but I think I’ll save it for later. I also found it pretty tricky and inconsistent to measure anyway, so I might just be measuring it poorly.
For reference, on the ground my upper longerons are at 8.4 degrees, and the top of the flaps are at 20.0 degrees when all the way up. So relative to the plane, the top surface of the flaps slope downward at 11.6 degrees. Maybe they should be 12? That’s a heck of a lot easier to measure in my opinion!!
That’s interesting I came up with exactly the same just less than 27 on the right 25 on the left. I also move the flap hinge back to try and get more up but then you lose the 2 59/64 dimension specified. At some point its close enough…