Tempest flaps question
 

Hi guys!

I'm building a 75" Tempest Mk. V from Ian Baileys plans ([link=http://user.tninet.se/~ytm843e/bailey.htm]Ian Bailey project[/link]). Made some modifications to the flaps, to achive a more scale-look:

I took two Robart 3/16" Super Hinge Points and separated them. The holes were enlarged to accept short pieces of brass tubes (3/32" inner dia.):
http://user.tninet.se/~yct679b/bailey-54.jpg

The flaps are made of 1/16" ply, four notches are cut where the hinges will be. Three pieces of 1/4" carbon fiber tubes are glued with Slow-Zap along the leading edge.
Pieces of 3/32" brass tubes are epoxied inside the carbon fiber tubes. (If I had found plastic tubes with correct dimensions I would have used that instead.) A 3/32" piano wire is cut to proper lenght. :
http://user.tninet.se/~yct679b/bailey-55.jpg

The wire is slided into the carbon fiber/brass tubes, don't forget the two middle hinges! The wire is secured with a FEW drops of CA at both ends. The outer hinges will be loose until the flap is glued to the wing.
The ribs are made of 1/16" balsa, more details will be added later.:
http://user.tninet.se/~yct679b/bailey-56.jpg

Full scale flaps:
http://user.tninet.se/~qsq272p/pr536cl-11.jpg


Question: The Tempest has four flap sections, on the plans they are operated by a single servo via push-rods and four bellcranks. Is there an easy way to operate the flaps using two servos, via a Y-pushrod? Or is the best solution to use four smaller servos? How large/small servos do I then need?


Cheers!
Christer Landberg
[link=http://user.tninet.se/~ytm843e/tempest.htm]The Hawker Tempest Page[/link]

RE: Tempest flaps question
 

Christer,
Impressive setup on the hinges for your Tempest!!! I have a 72" span Typhoon from Brian Taylor plans that has similar split flaps. I used two servos in the wing center section and bellcranks. When you mention servos with Y pushrods, I suspect you plan to locate them at the dihedral break. I don't see why that would not work. I did that on an F4U Corsair model; the full-size Corsair was set up that way. My Typhoon has standard JR 507 servos (approximately 40 ounce inches of torque) and they are capable of lowering the flaps to about 45 degrees deflection that I have set up. I do not know whether servos with lower output torque would work.
Chuck

RE: Tempest flaps question
 

Hi Christer, Ian B here, like the way you've used carbon fibre rods to replicate the full size flap construction, they wern't around when I did mine. I originally used just the one servo to drive all four flaps to keep the weight of the model to within the scale rules for F4c class and also to ensure even deflection of all four flaps, it worked, and I used a retract servo also, this gave plenty of pull and prevented any blowback as the flap deflection is 80 - 85 degrees if I remember correctly. There is no reason why two servos cannot be used or even four, but I feel this just complicates the issue and would you have easy access to the servos? If the servo(s) for the flaps is kept in the centre bay at least they are accessible. I must admit though I had each aileron with its own servo in the outer panels with no access hatch, buried permanently and never had any trouble, the inner undercarriage doors were driven by another retract servo kept in the centre bay along with the flap servo, the retracts on the prototype were modified Rom-Airs and the second Mk5 and Mk2 prototype were electric screwtrack. Like the build sequence you are doing, keep up the good work, I'm off to fly the Venom, got the gas turbine disease.

IB

RE: Tempest flaps question
 

Thanks Chuck and Ian for your replys.

I think my concern about the bellcranks arise from my Brian Taylor Tempest. They didn't work out (or I didn't work them out...) and I chose to exclude the flaps. But now everything is larger so I'll probably go for the bellcranks with use of ball links and a large single servo. (Listen to the designer [sm=wink.gif]!!)
Read the review in SRCI on Skyshark's Avenger where they first used Y-pushrods and got uneven moments and lots of play. No, I'll go for the bellcranks!

/Christer
[link=http://user.tninet.se/~ytm843e/tempest.htm]The Hawker Tempest Page[/link]

RE: Tempest flaps question
 

Im in the process of building the flaps on my Brian Taylor typhoon i tried sevros, but ive opted for bellcranks in the end, ive found as long as the flaps fit well and move well and there is some friction on the bellcrnks, they tend to work after a bit of playing around.

What i have found though is that if you use bellcranks the outer sections need more movment on the bellcrank to keep up with the inner ones.