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Nov 01, 2018, 09:48 AM
SLCPilot still sucks!
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Aileron Setup


My kid's high school Speedfest team is getting started on this year's plane. Below is a picture of last year's winning plane. We have increased the span a little this year to 65". Last year our roll rate using a single servo and torque rods was a little low. Workable but not snappy. We have to decide if we want to go with torque rods again, increase the aileron size, and hope it doesn't flex too much or go with 2 servos. Obviously the latter is more weight and drag with the linkages in the wind.

We are looking for ways too increase the torque rod stiffness and leaning toward a little zig zag carbon tow down the ailerons. Ideas are welcome and any build threads with beefy torque rods and longer ailerons would be helpful. I am not sure how much increasing aileron area chordwise as compared to span will actually help. And as a reference we were radared at 110mph coming out of a turn so I would estimate we are in the 120 straight and level range.

Thanks!

Dan
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Nov 01, 2018, 01:13 PM
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Congratulations on your winning performance. Most of today's fast pylon racers that use torque rods employ 1/8" drill rod. However some of the faster Quickie 500's (event 426) are using 3/32" rod. Reinforcing the ailerons is always a good idea, but you can probably just select harder balsa. Also the ailerons are too close to the wing root. Moving then out a foot will speed them up a lot. Check out any of the Quickie 500 designs to get an idea of what works on them. The Tower Hobbies Quick V would be a good place to start. Don't buy one, just look at the pictures. It looks like a Thunder Tiger engine in the picture? What are your rules? Also note that the slow Quickie 500's do around 115 mph. on the TT .40 or the Evolution .46. with an APC 9/6 prop.
Nov 01, 2018, 02:48 PM
SLCPilot still sucks!
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Quote:
Originally Posted by Greg Doe
Congratulations on your winning performance. Most of today's fast pylon racers that use torque rods employ 1/8" drill rod. However some of the faster Quickie 500's (event 426) are using 3/32" rod. Reinforcing the ailerons is always a good idea, but you can probably just select harder balsa. Also the ailerons are too close to the wing root. Moving then out a foot will speed them up a lot. Check out any of the Quickie 500 designs to get an idea of what works on them. The Tower Hobbies Quick V would be a good place to start. Don't buy one, just look at the pictures. It looks like a Thunder Tiger engine in the picture? What are your rules? Also note that the slow Quickie 500's do around 115 mph. on the TT .40 or the Evolution .46. with an APC 9/6 prop.
The rod sizing is helpful. This past year the ailerons were fairly close in. This was to keep the torque rods as short as possible. The concern is that as the torque rod gets longer it will twist more. Part of this challenge is that the plane is built by students. While I guide them on some things they don't build fast so we normally get done a week or so before the contest. We don't have much time for trouble shooting if linkages don't work right, flutter, slop, etc. We have to over engineer a lot of things that if this was my plane I would be less conservative and plan on fixing the things that need work.

This will be our 4th year. 1st year we got highest over all score and 2nd highest single flight score. The last 2 years we have gotten best flight score and highest overall score. This group of seniors have a lot of pressure to go out on top.

Here are the rules: http://speedfest.okstate.edu/Speedfe...les_India.html

There are 2 categories. Stock and modified. Stock is a stock Uproar and modified refers to the airframe. Basically it must ROG, have 570sq in., and use a stock OS 46 AXII.

Thanks!

Dan
Nov 01, 2018, 10:36 PM
Scott
Pylonracr's Avatar
Dan, you are back again this year. I was hoping you did well last year. Again, I will help any way I can. I would stick with strip ailerons and 1 servo for weight and aero reasons. Your aileron setup needs a little work, but it is easy. Shoot me a PM.

The same offer still stands, if you need wing cores I will supply them.

Scott
Nov 01, 2018, 10:51 PM
Registered User
Dan, looks like Scott is back on your team. That's good news. I'd still recommend 1/8" torque rods for your ailerons. You can use brass tubing for your bearing, and use a small length of the same brass tubing for your push rod connection. In practice you will flatten one end of the tubing, and drill a 1/16" hole for your clevis. Then that part gets soldered to the torque rod. This is how we did our Formula 1's 40 years ago, and it works just fine. I'll make you a set if you like, but I don't have a greedy bone in my body, so if Scott offers to make them for you let him have at it.
Nov 01, 2018, 11:06 PM
Scott
Pylonracr's Avatar
Quote:
Originally Posted by Greg Doe
Dan, looks like Scott is back on your team. That's good news. I'd still recommend 1/8" torque rods for your ailerons. You can use brass tubing for your bearing, and use a small length of the same brass tubing for your push rod connection. In practice you will flatten one end of the tubing, and drill a 1/16" hole for your clevis. Then that part gets soldered to the torque rod. This is how we did our Formula 1's 40 years ago, and it works just fine. I'll make you a set if you like, but I don't have a greedy bone in my body, so if Scott offers to make them for you let him have at it.
Greg, the more the merrier. I was offering up a set of foam cores (that I was going to have my buddy cut for me). I was going to send some Kevlar fabric with them and "Suggest" skinned hinges. A set of torque rods would be nice since every time I bend them they come out like crap.

Scott
Nov 02, 2018, 08:16 AM
SLCPilot still sucks!
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Thanks Scott! We made our own torque rods last year. I can't remember if we used 4-40 or 6-32 threaded rod ends. We have access to someone local who can help us cut cores this year so want to give the kids a shot at it.

I have considered skin hinging. I do have a little concern about getting it right but I suppose we could give it a shot and if we butcher it we can always cut them out and use normal hinges.

An interesting thing about last years plane, even though we used a Q500 tail, i think it was under sized. The first flight was with the CG at about 30% MAC. It was a handful and flew poorly. We ended up having to add 4oz of nose weight to get the CG to about 20% for the plane to fly locked in.

Dan
Nov 02, 2018, 09:41 AM
Scott
Pylonracr's Avatar
Dan, Skin hinges are easier than they seem. I will send you some Kevlar if you want to try. Of course, you will have to be using laminating resin to sheet your wings with. I am not surprised that a Q500 tail is too small. They have 500 inches of wing and fly a fair bit faster than your plane. We typically use quite low rates for flying so as not to over control, and high rates for takeoff and landing to be able to control it.

I still think you should cowl in around the engine. I feel it would be good for a few mph....

PM me about the ailerons.

Scott
Nov 02, 2018, 10:02 AM
Scott
Pylonracr's Avatar
One more thing.... What airfoil are you using?

Scott
Nov 02, 2018, 10:56 AM
SLCPilot still sucks!
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Sent you a PM Scott.

We have 2 primary reasons why we don't have a cowling:

1. We run out of time and it is down the list.
2. Simplicity. With a spinner nut if the engine back fires or sputter and loosens the prop we can reach in our pocket and retighten it in seconds and still not miss the round. We have a 2 minute window. With a cowl and spinner if if pops and throws the prop nut we miss the round. Basically, we win the overall because we don't miss a scoring round. Every round counts.

Another interesting thing we do is just glue the wing on. Saves weight. Not convenient but the plane doesn't fly every weekend. I estimate a couple ounce savings by leaving out the bolts and the blocks.
Nov 02, 2018, 03:26 PM
Registered User
Dan, Cowling, or no cowling you are spot on about not using a spinner. The rounded prop nut is the way to go. A cowl would have a cool factor, but at your speeds I don't believe it is worth the effort. Also I don't believe you will gain anything by increasing the wing span. High aspect ratio wings are slightly more efficient speed wise, but don't roll as well. Your race course has turns as well as straightaways. Your wing plan form on last years airplane looks good, but the volume of your v-tail, as you pointed out looks small. Bolt on wings are not that difficult, but I understand your reasoning. In my opinion (take it for what it's worth) skinned hinges are not worth the work. Those of us who build several airplanes a year, and have the process worked out, can do it without thinking. For you and your students it would be a learning event. Like anything there are even differing ideas about what materials to use, and how to do it. Scott recommend Kevlar, while I use Dacron. One final question. Can you use a bladder tank? A Tetra, or Jett tank allows you to needle the engine closer to peak rpm, because the engine doesn't lean as much from the ground to the air.
Nov 02, 2018, 03:42 PM
SLCPilot still sucks!
Thread OP
Quote:
Originally Posted by Greg Doe
Dan, Cowling, or no cowling you are spot on about not using a spinner. The rounded prop nut is the way to go. A cowl would have a cool factor, but at your speeds I don't believe it is worth the effort. Also I don't believe you will gain anything by increasing the wing span. High aspect ratio wings are slightly more efficient speed wise, but don't roll as well. Your race course has turns as well as straightaways. Your wing plan form on last years airplane looks good, but the volume of your v-tail, as you pointed out looks small. Bolt on wings are not that difficult, but I understand your reasoning. In my opinion (take it for what it's worth) skinned hinges are not worth the work. Those of us who build several airplanes a year, and have the process worked out, can do it without thinking. For you and your students it would be a learning event. Like anything there are even differing ideas about what materials to use, and how to do it. Scott recommend Kevlar, while I use Dacron. One final question. Can you use a bladder tank? A Tetra, or Jett tank allows you to needle the engine closer to peak rpm, because the engine doesn't lean as much from the ground to the air.
I appreciate the opinions. I am trying to avoid this becoming a "Dad" contest so that is the reason for a lot of our choices.

I would love to use a bubbless tank. It is within the rules but seems to be a place we usually try to save money. We reuse a lot of stuff from year to year like the radio gear, broken in engine, and even the tank. We did spend some money this year on better balsa. Last year we used some cheap stuff that was probalby 8lb balsa. We use my transmitter and rx.




Dan
Nov 02, 2018, 03:46 PM
Scott
Pylonracr's Avatar
Greg, good call on the bladder tank. Do you have a fueler to fill a bladder tank with? If you do I will donate a tank.

Scott
Nov 02, 2018, 03:48 PM
SLCPilot still sucks!
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Quote:
Originally Posted by Pylonracr
Greg, good call on the bladder tank. Do you have a fueler to fill a bladder tank with? If you do I will donate a tank.

Scott
Our posts crossed cyber space. Not sure what type of fueler is needed. We use a 4 oz tank and it is plenty for ground run up, 2 minute flight, and waiting for our turn to land with the engine running.

Oh and the fuel is provided at the contest and they just use a hand crank pump.
Nov 02, 2018, 05:02 PM
Scott
Pylonracr's Avatar
Bladder tanks are filled with what looks like a giant syringe. Go to Dub Jett website and look at them. If a local flyer has one you can borrow for the contest I will provide you with a tank. All pylon racers have one. You can not fill a bladder tank with a pump.

Scott


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