[Lct727]

Hello Everyone,

I just returned from OSH 09' and was inspired to build a RV-8 standard kit. They are remarkable airplane in appearance and the performance data looks amazing. I have already drawn out a panel ( two G3x with analog instruments for doing aerobatics) and a lycombing I-360 with a three bladed MT Prop. An idea of adding spades to the ailerons popped into my head last night and I was wondering what anyone thought about the idea. I have never flown in an RV-8 and have no idea how the roll rate was like, if it even needs them. My father has flown both a 8kcab Super Decathlon models with and without the aileron spades and says there is a drastic improvement in the roll rate with the spades. I asked the people at Van and they weren't to pleased about the idea... I'm excited to hear what you all think!!!!!!!!

 

[Mike S]

Welcome to VAF!!!!

Loren, welcome to VAF, good to have you aboard.

As to the spades, my vote is bad idea.

RVs are neat, fun aircraft, and most are aerobatic to some degree.

I would be concerned that the additional authority the spades give could over stress the airframe.

Best leave them to a design that is meant for aerobatics.

My $.02.

Again, welcome.

 

[Kevin Horton]

Hello Everyone,

I just returned from OSH 09' and was inspired to build a RV-8 standard kit. They are remarkable airplane in appearance and the performance data looks amazing. I have already drawn out a panel ( two G3x with analog instruments for doing aerobatics) and a lycombing I-360 with a three bladed MT Prop. An idea of adding spades to the ailerons popped into my head last night and I was wondering what anyone thought about the idea. I have never flown in an RV-8 and have no idea how the roll rate was like, if it even needs them. My father has flown both a 8kcab Super Decathlon models with and without the aileron spades and says there is a drastic improvement in the roll rate with the spades. I asked the people at Van and they weren't to pleased about the idea... I'm excited to hear what you all think!!!!!!!!

Spades reduce the stick force required for a given amount of aileron deflection. if you put in the same amount of stick force, you'll get a higher roll rate on an aircraft with spades. They are often used on aircraft with very large ailerons, as the large ailerons would require very large stick forces if the spades were not present.

On the RV series, you can get full aileron without too much effort, thus there is no real need for spades. They would change the aileron mass balance, and could affect the flutter speed. They would also require a major redesign of the aileron, to ensure it was strong enough to take the forces from the spade.

I recommend you drop the idea of spades on an RV.

 

[Bill Wightman]

Also, the idea of drawing out the panel before you've even ordered the kit might be a waste of time. The avionics market changes rapidly; new products are introduced every year.

Better to spend your time learning about what's available, interoperability between units works, etc. Its complicated, but a thorough search on this board will yield an avalanche of information.

Also, think about overall systems design/integration. There's LOTS of new ideas out there, some of which are really ingenious.

Lastly, forget all about the spades. The Friese ailerons on these airplanes are correctly balanced.

 

[Jamie]

I have never flown in an RV-8 and have no idea how the roll rate was like, if it even needs them.

No offense intended, but why try to improve on a design that you haven't even flown? One of the qualities that makes RVs so great is the way they fly without all sorts of superfluous structures all over the airframe (spades, VGs, etc).

My father has flown both a 8kcab Super Decathlon models with and without the aileron spades and says there is a drastic improvement in the roll rate with the spades.

Two completely different animals. My neighbor flies a Super Decathlon in airshows and he has spades on his. That thing has much longer (fabric covered) wings and just isn't even a fair comparison. It's a fun airplane, but when I flew on his wing to Sun-n-Fun I was pulled waaaaaaaaaay back to keep from outrunning him. It's a slow airplane. Slows airplane = slow roll rate.

I asked the people at Van and they weren't to pleased about the idea... I'm excited to hear what you all think!!!!!!!!

This is pretty much their take on any modification that builders come up with. Some of the mods are cool (fastback -8, for example) while others are ludicrous.

 

[Lct727]

WOW

This site really is an awesome tool for knowledge!!! Its great to have so much knowledge in one spot. As for the idea of the spades, that was a bad idea, i can see now. It would be like trying to but them on a C172 (Btw, I hate this plane, I believe everyone should have to learn on a taildragger first). Thats awesome that Van incorporated the frisk aileron design. The only airplane I've seen that in is the piper models. I love the piper models so much that I'm planning on putting the engine start switch underneath the seat like the PA-16 and PA-22 models....

 

[N941WR]

Welcome to the VAF!

...My father has flown both a 8kcab Super Decathlon models with and without the aileron spades and says there is a drastic improvement in the roll rate with the spades...

As others have said, bad idea. My -9, which is not an acro bird, rolls faster than the Decathlon I flew to keep current while building. Go figure.

... I love the piper models so much that I'm planning on putting the engine start switch underneath the seat like the PA-16 and PA-22 models....

Think long and hard about your panel layout. This may work well for a Piper but on your -8 you have the option to set up a very ergonomic panel or a really poor one. Take a look at the panels posted on the RV-8 section of this forum.

Some builders have incorporated the starter switch into their stick grips and others have simply put them on the panel. Not once have I heard of anyone putting one under the seat. Piper probably did that due to the battery location and expense of running wires forward for the contactor. Just a guess on my part, as I have no idea where the battery is on a PA-16 or -18.

 

[Bill Dicus]

?spades

The RV-8 flies beautiful recreational acro without spades; roll rate is perhaps 130-140 degrees/sec, very adequate, and forces are light and progressive as roll rate increases. I am lucky to fly a Pitts S-2A quite regularly. It rolls 230 deg/sec by the book. It's definitely faster in roll and easier and faster to get to full aileron deflection; without the spades aileron forces go from power steering light to very heavy (ailerons with symmetric airfoil). Both are delights to fly. I think the -8 is perfect for its role and wouldn't add spades. I was surprised to find that it flies beautifully inverted as well.

 

[Lct727]

Inverted Flight

Bill,

I'm very jealous of your flight time in the Pitts!!! I am planning on building the RV-8 as it is a good compromise aircraft for mild aerobatics and x-country capability. You raised an other question I had about the ability of the RV-8. How well does it fly upside down without a symmetrical airfoil...

 

[N941WR]

... You raised an other question I had about the ability of the RV-8. How well does it fly upside down without a symmetrical airfoil...

FYI - the NACA 2300 series airfoil used on the short wing RV's is semi-symmetrical.

 

[rbibb]

I don't know about the -8 but I suspect it is the same as the -4 in that, at higher airspeeds, the ailerons will experience a "stall" at close to full deflection (experienced as a vibration in the stick that might seem like flutter but isn't). The point is you don't need nor is it wise to push for full deflection at higher airspeeds in an RV. In fact you might bend the airplane if you do. Adding spades to lighten the forces required to get the ailerons to this stall condition is kinda self-defeating.

If you want "bang your helmet against the canopy" roll rates get an Extra, Pitts, or something designed for that. If you enjoy being actually able to see the countryside as you go over the top the RV is just fine.

Depending on what your flying experience has been the RV will probably be the most responsive, lightest control aircraft you've ever flown so you probably won't notice that you can't roll 200 plus degrees a second in one.

 

[Neal@F14]

Pushbutton Starter Switches

Pushbutton starter switches like the old Pipers had (my Cherokee has one) are coming back into fashion.

Although you can put your starter button anywhere you please, as long as you can get the two wires run to it, rather than putting it in an obscure location in the aircraft, I'd highly recommend locating it where you can easily get to either the stick or the throttle/mixture quadrant while pressing the button to crank the starter. The reasoning behind this is that in a taildragger, you kinda want to ensure the tail stays down in case the engine suddenly roars to life at a high rpm when it starts up (e.g. by keeping keep the stick held firmly all the way back while starting up). Plus, you want to have your hand on the throttle and possibly also the mixture too at the same time, while cranking the engine, especially if you go with a fuel injected engine, since they can be a royal pain to hot-start, and need all kinds of movement of the mixture and throttle controls as the engine begins to light up while cranking the starter all at the same time. Unfortunately most humans aren't equipped with three arms and hands. That's why some builders like their starter buttons on the stick, but pushbutton switches that fit inside stick grips tend to be small and kind of wimpy to handle the current draw of a big starter solenoid relay. Daisy-chaining an extra relay in the circuit such that a tiny stick grip pushbutton switch keys a smaller relay that in turn completes the circuit for the big starter relay (solenoid) will fix that problem, but adds complexity. There's also the problem of accidentally hitting a stick-mounted starter button after the engine is already running and embarassingly (and eventually expensively) grinding your starter's gear up against the already spinning flywheel ring gear. Ouch. We've all heard that sound before, hopefully only in our automobiles

If I were building an -8, if possible I'd like to try to see if I could locate a starter button very near the throttle quadrant such that maybe I could press the button and work the throttle and mixture levers all simultaneously with my left hand, while leaving my right hand free to hang onto the stick. A long time ago when I was a child, my dad had a boat with an old 6-cylinder outboard Mercury 2-stroke engine on it. It had the starter button located directly on top of a pistol grip combined throttle & gear shift single handle so that you pushed the button down with your thumb to crank the engine while you advanced the throttle lever to go forward, or pulled the lever all the way back past a neutral detent to shift into reverse gear. It worked really neat and allowed you to keep your hands on all the wheel and throttle/gear lever at all times. Interestingly, that old boat had the driver controls on the left side too, not the right side like most other boats.

 

[N941WR]

...If I were building an -8, if possible I'd like to try to see if I could locate a starter button very near the throttle quadrant such that maybe I could press the button and work the throttle and mixture levers all simultaneously with my left hand, while leaving my right hand free to hang onto the stick...

Not such a good idea. On the -8, put the starter and mag switches on the right side, if not on the stick. Hold the stick with your legs, work the throttle and mixture with the left hand and press the starter with your right hand. (Put all the other switches on the left side so you don?t have to take your hand off the stick to activate them.)

Those with injected engines will be moving both the throttle and mixture at the same time, thus it is very difficult to do that while pressing a starter button.

For the S-b-S models, put the master, mags, and starter on the left side. That allows you to play with the throttle and mixture with the right hand. (And all the other switches should be placed so they can be activated with the right hand.)

Either way, it is your plane, build it how you want.

 

[Andy Hill]

I don't know about the -8 but I suspect it is the same as the -4 in that, at higher airspeeds, the ailerons will experience a "stall" at close to full deflection (experienced as a vibration in the stick that might seem like flutter but isn't).

Yes - RV-8 does that... "Aileron Banging" (not violent) at full deflection.. an "RV characteristic"

The RV-8 flies beautiful recreational acro without spades; roll rate is perhaps 130-140 degrees/sec,

I'd agree, except that if the Dynon is accurate, which goes grey at >150deg/s, you can achieve this The Dynon needs 5s S&L to "re-erect", so my aeros sequence involves "toppling it (>150deg/s) in the first manoeuvre and ensure it stays that way until the end...

How well does it fly upside down without a symmetrical airfoil...

I am doing the testing on an RV-8 with a full inverted Oil System. We did ~45s inverted with little effort, and does not require an "extreme" nose up attitude to maintain level.

As an aside, we then tried it with the "non flop-tube tank" on an IO-360, 24x24, Full Rich (50Litres/hr? 13USG/hr?). It went 20s before spluttering. So those considering Flop Tubes on IO engines - seems not necessary unless you want serious inverted capability i.e. you are also fitting a FULL Inverted Oil system.

I am lucky enough to now fly the Extra 300, and of course the RV8 roll rate is nothing like that... However, given the specialist role of the Extra, and costs, the RV-8 deserves it's title of "mini-Extra". Out of the extreme areas of the Extra, the RV-8 will fly on the wing of an Extra at the same RPM / MAP, at half the fuel flow, and 1/5th the capital cost

Andy & Ellie Hill
RV-8 G-HILZ
RV-8 Formation Aeros

 

[Robert Anglin]

One other little thing

One other little thing here. There is a torsional stress imparted into the long axis of the wing when diflection of the controle surface is made. You realy want to keep this force with-in a safe range and not be over flexing the wing each time you make a hard input. Work hardening in a metal wing may dampen your day some time along the way!!
Your as always R.E.A.III #80888

 

[Bill Dicus]

RV8

Loren: I didn't know the airfoil was "semi-symmetrical" and expected the -8 to require a relatively high angle of attack to fly level inverted. In fact, the angle seems minimally increased compared to upright and the airplane flies easily and comfortable inverted. The -3 g limit is somewhat constraining. I chose not to equip mine with inverted fuel and oil. You're right - the Pitts is great fun. If you come to Milwaukee give me a call and we'll try to arrange a ride. Bill

 

[pierre smith]

Just watch this video....

...of a South American fully inverted -6A perform. The upside down pitch angle is amazingly slight. The video also shows just exactly what these airplanes are capable of.....much more than most of their owners!

http://www.youtube.com/watch?v=m8gM__5Xlds

Regards,

 

[flyeyes]

Not such a good idea. On the -8, put the starter and mag switches on the right side, if not on the stick. Hold the stick with your legs, work the throttle and mixture with the left hand and press the starter with your right hand. (Put all the other switches on the left side so you don?t have to take your hand off the stick to activate them.)

Those with injected engines will be moving both the throttle and mixture at the same time, thus it is very difficult to do that while pressing a starter button.
(snip)
Either way, it is your plane, build it how you want.

I would respectfully disagree

In my -8, I put the mag switches, boost pump, and start enable in a little group above and in front of the throttle on the left. The actual start switch is on the stick. I can easily reach all the switches with the heel of my hand on the throttle, and manipulating throttle and mixture is pretty simple with just my left hand for hot starts (IO-360).

I'm a big believer in grouping switches by function, and like having all the "engine" switches in one spot. I try to avoid having rows of identical toggles, unless they have similar functions (like external lights). I can grab any switch in the cockpit without having to look for it.

 

[N941WR]

I would respectfully disagree

In my -8, I put the mag switches, boost pump, and start enable in a little group above and in front of the throttle on the left. The actual start switch is on the stick. I can easily reach all the switches with the heel of my hand on the throttle, and manipulating throttle and mixture is pretty simple with just my left hand for hot starts (IO-360).

I'm a big believer in grouping switches by function, and like having all the "engine" switches in one spot. I try to avoid having rows of identical toggles, unless they have similar functions (like external lights). I can grab any switch in the cockpit without having to look for it.

James,

I agree with you 100%, grouping switches by function is the only way to go.

He talked about putting the starter switch by the throttle so you could move the levers while pushing the starter button, all with your left hand. That is what I took exception to.

I also mentioned putting the starter switch on the stick grip, which is a cool idea, even if it adds complexity. (Note, for those of you who are reading this, put a lock out on any stick grip starter so you can't accidentally engage the starter when the engine is running.)

However, for a simple setup, putting the starting switches on the right, (master, mags, starter, etc.) is the way to go, IMHO. Then you can put your flight switches (fuel pump, landing & taxi lights, strobes, position lights, whatever), over on the left where you don't have to take your hand off the stick to operate them in flight. This is for a cockpit set for the PIC to use his right hand on the stick and left hand on the throttle. It is the reverse for those of us who fly with their left hand on the stick and right hand on the throttle.

 

[Andy Hill]

Loren: I didn't know the airfoil was "semi-symmetrical" and expected the -8 to require a relatively high angle of attack to fly level inverted. In fact, the angle seems minimally increased compared to upright and the airplane flies easily and comfortable inverted.

Further testing today... 24x24, 1 min inverted, S&L, was only 5-10K slower than upright - surprised me too!

Andy

 

[Alan Carroll]

Stick grip starter switch

I also mentioned putting the starter switch on the stick grip, which is a cool idea, even if it adds complexity. (Note, for those of you who are reading this, put a lock out on any stick grip starter so you can't accidentally engage the starter when the engine is running.)

I put the starter button on the lower part of the stick grip. I wired it (and a red "starter armed" light) through the normally-closed pole of an oil pressure switch, which prevents accidental engagement with the engine running. This setup has worked fine so far (530 hours).

 

[Bill Dicus]

A nice surprise. How'd your head feel @ 1 min? Bill

 

[Andy Hill]

How'd your head feel @ 1 min?

Surprisingly OK! I'd never done sustained inverted before... but somebody asking me to test fly his RV-8, with an Inverted System - well it had to be done

As you might expect, enough attention was spent watching Oil P etc., and maintaining S&L, that I did not really notice. Suspect it would not have been pleasant as a "passenger"

Andy
RV-8 G-HILZ
In action