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HP Aircraft wing tip

Larry DeCamp

Well Known Member
FWIW, my home made tips from Steve Smith’s generous guidance save weight. Steve coached me after I asked him about flat tip merit, before the HP commercial relationship developed.

In addition to the 3mph speed increase they are six pounds lighter than 415 tips. 2.5 lb each vs 5.5ea for 415’s. Mine are made of 3layer glass and due to the curved surfaces they are very stiff.
 
Pics?

Not exactly the internet standard of "Pictures, or it didn't happen." but would like to see them if you could post some shots.
 
The HP Aircraft LLC short tips are now shipping with provision for lights (nav + strobe). The set that Bob made for me are super light, since they are just 2 plies of 12 oz Knytex. I weighed them today and they are 2.5 lb.

I'll post pictures of the tips installed tomorrow after I get them on. Paint drying.
 
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I found some pix at the HP Aircraft LLC website here: https://hpaircraftblog.wordpress.com/short-wingtips-for-rv-4-through-rv-8/
The pix are of tips without the lighting provision so I’m looking forward to seeing Steve’s installed units.
I have a Rocket I’m finishing up that has 715 bat-wing tips. Those HP stubbies would certainly be a worthwhile mod.

Question: does HP’s provision for the lights mirror the Van’s provision enough for the the Fly LED kits to be used?

PS: I learned a new word: pultruded. Quite the eclectic collection products that HP offers. Wish I had an L-39 that needed to loose its tip tanks…
 
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The HP Aircraft LLC short tips are now shipping with provision for lights (nav + strobe). The set that Bob made for me are super light, since they are just 2 plies of 12 oz Knytex. I weighed them today and they are 2.5 lb.

I'll post pictures of the tips installed tomorrow after I get them on. Paint drying.

This thing needs a picture (Taper wings for RV8)
 

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This thing needs a picture (Taper wings for RV8)

We periodically post updates on the tapered composite wing project in a separate thread, but we are probably overdue. We have closed the wings, and chased all but one fuel tank leak. Should have that one fixed next weekend. Bob Mills has match-drilled the aluminum stub spars to fit his Rocket-6.

Next up will be a static load test, end of January. In the mean time, I am starting to work on the ailerons and flaps.
 
Question: does HP’s provision for the lights mirror the Van’s provision enough for the the Fly LED kits to be used?

The light cavity is sized to accept the AeroLEDs Pulsar modules. The FlyLED's fellow has developed a kit for these tips and I believe the first set is in the mail to Bob K.

Here are a couple of pictures.
wingtip4.jpg

wingtip3.jpg
sorry I should have made sure the aileron was positioned right. The match-up is perfect

wingtip5.jpg
 
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Question: does HP’s provision for the lights mirror the Van’s provision enough for the the Fly LED kits to be used?

Good question! In fact, Fly LEDs has already developed a nav/strobe kit for these wingtips. I'm getting one on order so I can assemble and install it in a set.
 
How much drag does the clear lens and screws add?

In other words, how flush can you make it................
 
How much drag does the clear lens and screws add?

In other words, how flush can you make it................

Not sure you could even measure the drag difference in any case, but the degree of flushness depends somewhat on your workmanship and time investment. The recess is approximately the same depth as the thickness of the lens material, but not exactly. The lens is not perfectly uniform in thickess either.

So, if you want it really perfectly flush, you can build up the mating surface with epoxy/microballoons (or bondo) until the lens is as flush as you like.

The molded shape of the lens is very good - it better be, it was made on a plug that was cast in the tip mold. I found that it helps to make the attachment screw holes a little over size so the lens can settle where it likes best
 
Curious has anyone tried these on a Rocket that already has shorter wings. At what point having to little wing aspect ratio starts to hurt performance? Also wondering the gain compared to a good sharp sheared wingtip. It just says 3mph gain over a flat cut off tip.
 
Reflexing flaps

Are the flaps and ailerons reflexed a little (with tip matching) to get the fastest speed?

If I've got my facts straight (not guaranteed) the NACA 23012 airfoil that the RV-3/4/6/7/8 uses has less of a pitching moment than the Roncz airfoil of the RV-9/10/14 so reflexing the flaps (or ailerons) doesn't have the same effect.

You'll notice that the Roncz airfoil airplanes have a larger horizontal stab to balance the higher pitching moment. Reflexing the flaps reduces the pitching moment of the wing and unloads (reduces the (-) lift of) the stab in cruise which causes the increase in speed.

That's my story and I'm sticking to it....

Laird
 
Curious has anyone tried these on a Rocket that already has shorter wings. At what point having to little wing aspect ratio starts to hurt performance?

Bob Mills did at the Reno Air Races this year.

He, Steve or Bob K. should be the ones to comment as to the speed change.
 
...the Roncz airfoil of the RV-9/10/14...

The RV-9 does indeed have a Roncz airfoil. But the RV-10 and RV-14 have an airfoil that Steve Smith (scsmith) designed especially for Vans.

Curious has anyone tried these on a Rocket that already has shorter wings. At what point having to little wing aspect ratio starts to hurt performance? Also wondering the gain compared to a good sharp sheared wingtip. It just says 3mph gain over a flat cut off tip.

Bob Mills writes a bit about that in this earlier VAF thread.
 
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We periodically post updates on the tapered composite wing project in a separate thread, but we are probably overdue. We have closed the wings, and chased all but one fuel tank leak. Should have that one fixed next weekend. Bob Mills has match-drilled the aluminum stub spars to fit his Rocket-6.

Next up will be a static load test, end of January. In the mean time, I am starting to work on the ailerons and flaps.

I can't wait for the next update.
 
Ah-hem.....yes John Roncz did design the RV-9 airfoil. But as Bob K mentioned the RV10/14 airfoil is mine. Reducing pitching moment is a benefit, as you describe, except that all these airfoils have very low section pitching moment. The large tail was added to the -9 because of the large slotted flaps which do add quite a lot of pitching moment.

Reflex (negative flap) primarily helps by keeping the nose of the airfoil at the best angle to promote laminar flow. Both the -9 airfoil and the -10/14 airfoil do maintain a modest amount of laminar flow. The NACA 23013.5 on the earlier designs does not. If you have a -9 or -10/14, keep the bugs cleaned off the wing and don’t paint trim stripes on the leading edge.


If I've got my facts straight (not guaranteed) the NACA 23012 airfoil that the RV-3/4/6/7/8 uses has less of a pitching moment than the Roncz airfoil of the RV-9/10/14 so reflexing the flaps (or ailerons) doesn't have the same effect.

You'll notice that the Roncz airfoil airplanes have a larger horizontal stab to balance the higher pitching moment. Reflexing the flaps reduces the pitching moment of the wing and unloads (reduces the (-) lift of) the stab in cruise which causes the increase in speed.

That's my story and I'm sticking to it....

Laird
 
Ah-hem.....yes John Roncz did design the RV-9 airfoil. But as Bob K mentioned the RV10/14 airfoil is mine. Reducing pitching moment is a benefit, as you describe, except that all these airfoils have very low section pitching moment. The large tail was added to the -9 because of the large slotted flaps which do add quite a lot of pitching moment.

Reflex (negative flap) primarily helps by keeping the nose of the airfoil at the best angle to promote laminar flow. Both the -9 airfoil and the -10/14 airfoil do maintain a modest amount of laminar flow. The NACA 23013.5 on the earlier designs does not. If you have a -9 or -10/14, keep the bugs cleaned off the wing and don’t paint trim stripes on the leading edge.

Thanks for clearing up my mis-information Steve. I stand corrected and more informed!

Laird
PS. Wingtips look Awesome. Hope you sell a ton.
 
Comparison test data

Steve Smith and Bob Mills have been very busy at the HP workshop getting the tapered carbon fiber wings onto Bob's Rocket Six in time to turn laps at the NCAR Reno Air Races.

But we've finally made time to do some comparison testing between the HP racing wingtips and the stock W715-1 wingtips. We did Kevin Horten 3-leg GPS triangles at four different altitudes (6000, 7500, 9500, 11500 MSL), first with the HP tips, then with the factory tips two hours later.

As expected, we found a solid 3-knot improvement at 6000 feet, and the data graph points to more at lower altitudes. The crossover altitude appears to be right around 11,000 MSL.

wingtip-comparison.png


We also tested the stall speed, and found that it was only about 2 knots IAS faster with the short tips.
 
Some comments on our initial data:

The two test runs were really only a bit over an hour apart. The OAT warmed just 1 degree F from the first test series to the second. And the fuel load was the same for both test series.

The resolution of the GPS groundspeed readout on my 396 is 1 kt, so each individual speed point has a resolution (and probably accuracy) of +/- 1/2 kt.

The ability to stabilize conditions over the triangle leg is probably also in the 1/2 kt -- 1 kt range, and in fact I observed cases of 1 kt change in wind speed over the distance of a leg. So these data probably have error bars of about +/- 1 kt in TAS. The only way to improve that is to get more data. I think ForeFlight also outputs GPS speed to 1 kt resolution, so I don't have a tool to improve that. We will do another test run to try to get more statistical sample size when we can, but we wanted to get this out now.

Realistically, I think the cross-over is probably more in the 9500-10k altitude range. But the real key take away here is that down low, (below 7000 ft or so) shedding the extra wetted area of the stock tips does get you something in the ball park of 3 kts. At a cost of 2 kt increase in stall speed.

Another thing I noticed was quicker roll response - not that most of us need that. But if, for example, you like to do vertical rolls, you might get two full rolls instead of 1-1/2 before you poop out.


Steve Smith and Bob Mills have been very busy at the HP workshop getting the tapered carbon fiber wings onto Bob's Rocket Six in time to turn laps at the NCAR Reno Air Races.

But we've finally made time to do some comparison testing between the HP racing wingtips and the stock W715-1 wingtips. We did Kevin Horten 3-leg GPS triangles at four different altitudes (6000, 7500, 9500, 11500 MSL), first with the HP tips, then with the factory tips two hours later.

As expected, we found a solid 3-knot improvement at 6000 feet, and the data graph points to more at lower altitudes. The crossover altitude appears to be right around 11,000 MSL.

wingtip-comparison.png


We also tested the stall speed, and found that it was only about 2 knots IAS faster with the short tips.
 
Just put mine on

this was an easy up grade the stubby look is big winner with the lady’s faster would be a bonus as well. took very little work to smooth .. the light lens where the most troubling part … not scratching the lens … which i did. i’d like to thank the gentleman at HP who got them to me fast and followed up with good advice … and the folks at fly led helped me get the lights i screwed up fixed … will post pics when i figure out how tommorw …
 
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Just put mine on

this was an easy up grade the stubby look is big winner with the lady’s faster would be a bonus as well. took very little work to smooth .. the light lens where the most troubling part … not scratching the lens … which i did. i’d like to thank the gentleman at HP who got them to me fast and followed up with good advice … and the folks at fly led helped me get the lights i screwed up fixed … will post pics when i figure out how tommorw …
 
How do these tips affect the stall speed? I'd expect it to come up, but I don't see any mention of the new stall speed here.
 
Another way to compare wing tips is to fly with different tips on each wing. Yaw will clearly show any speed differences. I did this on my EVO after making some nice wing tips based on a modified 337 tip.
I had taken a paper airfoil shape of the last wing rib and compared it to many planes at Sun and fun until I found that the 337 was close.
Many hours of building modified 337 tips to find that there was a lot more drag then the stock metal EVO tips
I did not check at altitude where the 337 tip may have shown an advantage
 
I did note that there was a difference in stall speed with the longer tips, a knot or two lower with the flat tips.
Also, try using metal tape to close all lightening holes on outer and inner wing ribs. The wing can act like an air pump and sealing these holes seemed to help with speed improvements. I did not try this, but taping holes on one wing only would demonstrate yaw effect if there was a difference
 
HP Aircraft Inc. wing tip question

We have covered stall speed and cruise speed difference.
Should any adjustment be considered in GROSS weight declaration with the small tips ?
 
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...Should any adjustment be considered in GROSS weight declaration with the small tips ?

No, no change to gross weight.

Also, we just got another batch of the lenses for the lighted versions of the short tips, and these are a bit better than the first batch. They are still not canopy-quality optics, but serve perfectly well for wingtip lights. We're still working on duplicating them in high-quality acrylic.
 
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I had very similar results...

Some comments on our initial data:

The two test runs were really only a bit over an hour apart. The OAT warmed just 1 degree F from the first test series to the second. And the fuel load was the same for both test series.

The resolution of the GPS groundspeed readout on my 396 is 1 kt, so each individual speed point has a resolution (and probably accuracy) of +/- 1/2 kt.

The ability to stabilize conditions over the triangle leg is probably also in the 1/2 kt -- 1 kt range, and in fact I observed cases of 1 kt change in wind speed over the distance of a leg. So these data probably have error bars of about +/- 1 kt in TAS. The only way to improve that is to get more data. I think ForeFlight also outputs GPS speed to 1 kt resolution, so I don't have a tool to improve that. We will do another test run to try to get more statistical sample size when we can, but we wanted to get this out now.

Realistically, I think the cross-over is probably more in the 9500-10k altitude range. But the real key take away here is that down low, (below 7000 ft or so) shedding the extra wetted area of the stock tips does get you something in the ball park of 3 kts. At a cost of 2 kt increase in stall speed.

Another thing I noticed was quicker roll response - not that most of us need that. But if, for example, you like to do vertical rolls, you might get two full rolls instead of 1-1/2 before you poop out.

Steve,

I was unaware of this thread until this morning. Several years ago I made some very similar tips for SARL racing for my RV4, pounded them out of aluminum. They are very light. Anyway, your performance numbers are very similar to what I measured. The cross over where there is no advantage either way was about 10500 msl as you suggested. Roll rate is noticeably faster, speed is up by 3-4 knots down low. It stalls about 4 knots faster, and since I sometimes go into some very high density altitude airports, it feels even more than that. My max speeds are quite a bit higher, last year at the AVC I was doing about 204 knots TAS.

It is good to see someone else getting similar performance with more or less thee same mods.
 
You had me at 5 lbs! I'm going for a super light and fast(ish) RV-7 and these should support the cause.
 
I just received my wing tips and I have to say WOW they look sweet. The surface finish is fantastic. I weighed the glass portion (no trailing edge rib or plexi) and they come in at 1100 grams lighter per tip than the stock tips. This equates to 5lbs, plus there’s added benefit of moving the CG ever so slightly forward. Im also optimistic about installing a landing light as well as nav/stobes behind the tiny tip lens.
 
I just received my wing tips and I have to say WOW they look sweet. The surface finish is fantastic. I weighed the glass portion (no trailing edge rib or plexi) and they come in at 1100 grams lighter per tip than the stock tips. This equates to 5lbs, plus there’s added benefit of moving the CG ever so slightly forward. Im also optimistic about installing a landing light as well as nav/stobes behind the tiny tip lens.

Thanks Rob,

we did recently change the lay-up schedule in a way that makes them both lighter and improves the surface, so glad that paid off.

We are optimistic that the FlyLEDs single spot will fit, but we haven't tried it yet. Perhaps you could try one and report back. One advantage is that they fit into the same type of mount as a std Vans tip light.

https://flyleds.com/products/#!/Single-Spotlight/p/108852015/category=0
 
How do I go about getting a set of these for my 4 project? I've tried the contact on HP website but no response yet. Thanks
 
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