B Model Flap Question

[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.

[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.

[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.

[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?

[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.

[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?

[T41pilot]

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.

[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!

[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

[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!