MaxQ

First off, I'm a rookie to 40 size AMA pylon racing. However my limited racing experience leads me to believe its not V-tail vs Conventional, highwing vs low wing, but horsepower and the cleanest line that wins races. Flying the complete course helps too. I believe there are some aerodynamic advantages to the Quickie V-tail design which are
1) The pitch-up/pitch-down control surfaces(V-tails) are generally in "cleaner" air. Not subject to wing and prop wake. Crisper response, better control effectiveness. If manufacturing alignments are true there should be no yaw component to pitch-up or down inputs.
2) Less potential for a aileron deflection to interact with the V-tail local angle of attack(longitudinal hunting, possible yaw interactions).
3) Eliminate right angle(90 deg) surface interfaces(ie wing to fuselage, horizontal to fuselage, vertical to horizontal). Without fillets or a generous radius these areas are very draggie. V-tails are cleaner.
These are just some thoughts.

HP+Skill=Wins

MaxQ

kane

Quick summary:

1. it doesn't matter??
2. how did COS of an angle get into this debate? Jonathan, I am happy to see that our educational system is working.
3. There are way too many aerodynamic variables acting on any airplane to quickly summarize a specific situation. It might be a plus in one case but may have 3 other negative affects somewhere else and visa versa.
3. ground effect, let's all race in it?
4. pilot skill
5. pilot skill
6. STRAIGHT airplane
7. horsepower
8. did I mention pilot skill?
9. CG placement
10. where the wheels at.

last but not least: STIFFNESS, which is always a good thing!


Ed, you bring the RUM and I will explain all of these trigonometric functions for you.

COSINE is a trigonometric function that for an acute angle is the ratio between the leg adjacent to the angle when it is considered part of a right triangle and the hypotenuse (Websters Dictionary)

gi8u2racing

My Feedback: (11)

MaxQ-
yes, a high winged plane with a conventioanl tail wouldn't be good beceause the wake of the wing goes right into the tail. But because we have a low wing, it is not in the wake. And a conventional tail is more effective, because when you pull up on a v-tail, the right ruddervator prudues some left yaw effect, and the left ruddervator produces right yaw. But the counteract each other, so you dont feel it. But, a conventional tail gives all the control movement into pushing the tail down, so you need less travel. Look at my site under More Pictures to see the physics behind this.

kane-
yes, pilot skill and horsepower matters. without that, it is hard to win any race. that was the point of this thread. you all seem to know about the plus's of a high winged v-tail, so i'm just showing you all the plus's of a low winged, conventional tail. and yes, stiffness is an issure as well. and so is straightness and gear placement. my point is that we have developed a plane with all of the above considerations, and some well thought out unique components (and some prefer to be unique), and maybe it's time for others to give it a try.

the ground effect helps on landing, and i'm not even sure what you're "let's race in it" comment is about, but i'd love to watch a race where no one goes more than 5 ft. off the deck!

look at my site for a visual explanation of the sin(55º)

gi8u2racing

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on my site, i have added some pictures of the kit contents, kit options, and some pictures of the plane

Jeff Leavitt

full scale pilots are taught about ground effect. You are taught that ground effect exists for approx. one half of the wing span above the ground. No question in my mind that it does influence how our racers take off and land.

I have built quite a few V tails. No more. I love the looks but the pleasure isn't worth the extra work. The conventional tail has proven to me to be as fast, and a better flyer all through the flight envelope.

Sounds to me like the gi8u2 group has focused on developing the best possible flight platform. The "fly's like it's on rails" condition is probably the most important quality a good racer has and it's not a given. Takes experience to take a capable airplane and trim it to fly the course like it's on rails.

There are a lot of really good pilots out there, but for a really good experience, watch Chip Hyde fly 428. Awesome!

My hat's off to the gi8u2 group for the no BS approach to quickee racing.... Best Regards, Jeff.....

Ed Smith

It was posted:-

COSINE is a trigonometric function that for an acute angle is the ratio between the leg adjacent to the angle when it is considered part of a right triangle and the hypotenuse (Websters Dictionary)


I might fly like one, even look like one but what on earth has a hippopotamus have to do with this discussion?

Ed S

stand-RCU

There may be some wasted control forces while pulling through a pylon turn for a v-tail over a conventional configuration, but the fact is that there is less drag in a V-tail while NOT turning! The drag formed by having a vertical fin joined a 90 degrees to the horizontal stab exists all the time even in the turn and that more than offsets the control forces of a V-tail.

The larger you can make the angle of the joint the less drag; i.e., 110 degrees in a V-tail. The angle formed under the V is 125 degrees to the fuse. That's why they have less drag. Also note that almost all the faster V-tails bring the tail out at the upper corner of the fuse eliminating another angle to create drag. I.E., if you bring it out of the fuse at the middle you have created two joint angles of 55 degrees adding some drag!

As for a low wing, if you add dihedral to the wing, the joint at the fuse is less that 90 degrees an this causes MORE drag. Also since the airflow over the top surface of the wing is faster than the bottom and it must contend with that bad angle formed at the fuse, guess what? More drag.

I do like the looks of the low wing conventional tail Q-500's, but they are at a disadvantage when it comes to potential drag forces. Of course a poorly configured v-tail, high wing design can have drag issues as well.

Stan D.

gi8u2racing

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due to all the traffic at our site, the site has become overloaded and therefore inaccessible now. I will get this back up tomorrow. Basically, yahoo wants some money now. I am willing to pay this since it seems that the site is actually being used. Hopefully we can sell some kits to justify this.
but i can still field any emails. please feel free to ask any questions at [email protected] or just drop me a personal message. I can send you pictures if you wish. sorry for the inconvenience.

Per_N

Hi Jonathan

Your link is not working, maybe it's temporary.

I really like to see this plane you are talking about, I hope you have pictures on your site...

Per

Daniel Z

I have mention that turning on pylon1 with the plane totally vertical the INDUCED drag of the tail is the main diference between V tails and conventional ones.
Vtails have both surfaces angled 70 deg from the vertical and conventional ones are totally vertical witch causes more drag and slower exit off, maybe in a straight line the effect of the tail can be less important but we are always turning.
Daniel

IRLJR

My Feedback: (37)

Does anyone here know where the most flying time during a heat is spent? In the turns or on the straight aways?

One other thought--
During a heat, one mistake in flying and any so-called "advantage" is lost.

Thanks
IRL

vector-RCU

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Hi Irl,
Hey did you see Frank has the NEPRO site switched to the new address ? WWW.NEPRO.ORG Really looking forward to some racing next year. Say hi to Fran and Ralph for me.

Lewis