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Novel ideas that worked/did not work as expected

Vern

Well Known Member
Yesterday at the RV Squadron cookout one of our guests mentioned how excited he had been to mount his airbox fairing on his 6A lower cowl using screws so he could do oil changes/ minor mx without having to remove his entire lower cowl. I asked how he liked it now that he had installed it that way and he told me it was a waste of time-don't do it!

I got to thinking about some of my time-wasting hair-brained ideas and thought if we all shared our experiences we could help those coming along behind us.

So, what ideas have you tried that were good ideas or complete time-wasters?
 
Gap seals

Hi everybody,
I built a Cassutt F-1 racer in the seventies with fabric tailfeathers. I eventually got around to adding gap seals which were nothing more than a strip of fabric attached to the upper side of the stab and down through the gap and attached to the underside of the elevator. I was amazed that I needed a LOT more down elevator at WOT and had to add four washers under the leading edge of the stab and picked up an easy 5 MPH. I've often wished that all my speed mods yielded that much that easily! About 25 cents worth of parts!! ;)
 
Not yet

Hi Dan,
I haven't yet. Last year I mentioned gap seals and one poster said that you shouldn't do it on the RVs because the Friese (sp) ailerons get heavier or less responsive or something like that. I do have Dave Anders 5 pages of mods that he has done to his -4 and gap seals are a part of those mods.

I can paste the mods for all to see but I don't know if DR will allow five pages. Have you done any gap seals?

Another interesting mod that Dave and also Tracy Saylor (237 MPH RV 6!) have done is to use the ailerons and elevators like the 9 that have thinner trailing edges, riveted together. Tracy says the ailerons feel much better...faster too,
 
By all means, Post!

Pierre,

I'm sure Doug wouldn't mind 5 pages (or 5 posts) of mods to make RV's faster. I've seen tons more space than that taken up arguing over fuse blocks or circuit breakers which won't make an RV any faster at all! :)
 
pierre smith said:
I can paste the mods for all to see but I don't know if DR will allow five pages. Have you done any gap seals?
No, I haven't really done any drag reduction mods at all. One time I taped over all the gaps (not control surfaces, but fairings and joints) and did a before/after speed run. Not a single knot improvement.

...use the ailerons and elevators like the 9 that have thinner trailing edges, riveted together. Tracy says the ailerons feel much better...faster too,
It would be pretty easy to try this without having to build new ailerons & elevators. You could probably make a trailing edge "add on" out of wood/composite that would attach to the existing folded trailing edge. I haven't tried that either...doubt it would add up to 1/2 a knot, but I'm a skeptic.

I'm a believer in "large tangible" drag reduction items like reducing cooling drag, rigging the airplane & fairings straight, and getting stuff out of the slipstream where able. I don't really have time to nickel and dime 1/10 knot improvements...not my mission but I'm glad that other people do have that mission because it's really interesting to hear what works and doesn't work.
 
How?

I tried to copy and paste the 5 pages from Dave Anders but I don't have that option to paste here. If I try to attach it as a file, it says it's too big. How else do I transfer the five pages, Doug, or anybody?
 
Dave Anders mods

RV-4 Performance Increase with each Modification
1992 approx 220 mph stock IO360
1) cold induction plenum

2) "Y" stack exhaust
Mp 195
Prop efficiency .78
Speed 220
Flat plate area 2.0
1993 Sun 100 race 230 mph
3) electronic ignition
4} lower firewall clean-up and fairing
5} increased rpm to optimum helical tip speed (2925 rpm)
6) dynamic balance (.004 ips or better)
Note: ~ 2 hp / cylinder / 100 rpm Hp 211
results in +16 hp Prop efficiency .78
hp increased 8 mph speed 230
drag reduction increased 2 mph flat plate area 1.95
1994 Sun 100 race 235 mph
7) Racing tail wheel (no steering)
8) gap seal ( 4 single exhaust - no effect)
9) lamb tire
10) 2 piece wheel pants
Note: 5.0% ^ Flat plate area HP 211
Increased ~ 5 mph -/ to 10 hp prop efficiency .78
Drag reduction increased 5 mph speed 235
Flat plate area 1.85
1995 Kilo Lima Trials 248 mph
11) B&C alternator
12) Engine (compression 10:1 & flow cylinders)
Prop (~ 80.5%, thinned & changed twist) -80.5% per Hartzell Fuel injection servo modifications
13) Plenum
14) Cowling inlet rings
15) 4 into 1 exhaust (HPC coated)
16) Augmentor outlet (jet effect)
(Should be shorter exhaust collector)
17) Cooling tunnel fuselage mod if action
18) Improved firewall fairings
(Added convergence fairings - x* ^ 35 is best)
19) new gear teg fairings (laminar airfoil w/pressure recovery)
Hp increased 7 mph HP 225
Drag reduction increased 6 mpti prop efficiency 80.5
Speed 248
Flat plate area 1.74
1997 March 254 mph (preparation for Cafe Triaviathon)
20) Inlet ring and cowling modification to increase servo intake ram air
21) aileron cuff position (re-rigged)
22) aileron hinge bracket canoe fairings
23) Ervg mod (increased compression, ceramic tops ~ 11:1 and friction coated skirts. Friction coated oil gears and advanced cam gear timing)
24) wing tips (higher aspect ratio, lower drag)
hp increased 3.5 mph Hp 235
drag reduction increased 2.5 mph prop efficiency 80.5
Speed 254
Flat plate area 1.68
1997 Sept 27 Triaviathon Record
2S0.7 mph TAS @ 6000' max. speed
44.7 mph min. speed
3308.2 fpm average rate of climb
New Score 2380 (breaking old record by 81%)
Note: it was very calm & cold, flat plate area now 1.45 - 1.5 ? top speed at sun 100 race should be approx 264 mph
Onfy the triaviathon record was calculated to standard day. All other race data was race day conditions (poorer than standard day) resulting in sub-optimum performance.
20OQ Sun 100 race 261 mph (standing start)
25) Thermal barriers under the cowl. (No idea if it did anything)
26) New canopy and fastback modification
27) painted the plane
Note: I thought I should hp 235
have been faster prop efficiency 80,5
Speed 261
Hp increased 1 mph Flat p4ate area 1.5
drag reduction increased 6 mph

Current best speed under perfect conditions 265+ mph
Conclusions:
Over the years,
Th? increase in hp 195 hp to 235 hp (40 hp total)
Increased Prop efficiency 78% to &0.5%
So:
235 X 8CL5 X 146225 - 239.5 mph 2
Means: (220 mph to 264 mph = 44 mph overall gain)
19.5 mph increase since 1992 was due to the hp & prop
24.5 mph was due to drag reduction which represents a 27% reduction in Total Airframe Drag
(20% faster = 42% reduction in drag if constant pwr. ? remaining 15% reductk>n= a 23% increase in hp & 2,5% in prop eff.)
If you add each gain from hp from each race it = 19.5 mph
Drag reduction is better, lower cost, lower maintenance arvd you get free speed or increased mileage.
Fuel savings from:
1) drag reduction
2) electronic ignition: 1 - 10-% from sea level to 12,000'
3) high compression: >? Torqug Jn-cx&ase^ _%.
Mileage gain *f 2X's hp 8:1 to 9:1 2
9:1 to 10:1 1.7
Mods produced 10:1 to 11:1 1.5
1) increased speed 11:1 to 12:1 1.3
2) increased economy 12:1 to 13:1 1.1
My speed increased 44 mph or 20% faster than stock. However, economy cruise at 14,OOO' @ 190 mph ground speed requires 4.5 gph resulting in ~ 42 mpg, or ~ 9OO mile range w/reserve.
Flying with other RV's w/o any of the mods uses ~ 22% less fuel per stop especially when were high and lean.

If lower than 65% power you can run Lean Of Peak.
1850 hrs X 8 gals/hr ?~ 14,800 gals burned
X i3.75/pal $ 55,500 X 20% $ 11,100 savings
27% of increased performance from drag reduction
27% + 42% (if constant pwr) = 64% X $11,100 - $ 7,100 from drag reduction alone
Approx 135 gals free/yr for 14 years
 
Not quite

I copied and pasted from Word pad and the result is definitely not the same as the pages I have....sorry. I don't yet know how to submit them EXACTLY as they're written,
 
Post, Pierre! Post!

If you hit the character limit on one page, just post a reply to that one and so on. Do it as often as you like.

b,
d
 
Paste them into NotePad first. That will strip out any application-specific code. Then copy/paste THAT into the forums.

There is a 8,000 character limite per post, so it might take you a new thread and a couple replies.

b,
d
 
Doug-

What if he sent it to you as a word file or whatever then you could post it as a permanent link somewhere on the site?

T.
 
posting text

Pierre, If you can load your information into ms notepad it will clean out all the special characters. You might need to go over the text after you load it into notepad and do some restructure. The advantage of notepad when you post to the internet is it posts a clean text just like the HTML without special charcters. Its the special characters that scramble your text.. Nice job any way you look at it..
 
Thanks.....

Exactly what I was looking for.........thanks a lot Mikey. I saved most of the article and couldn't find the link. Dave must be a super devoted kinda guy to extract THAT much speed from an RV 4, even with an estimated 235 HP,
 
Mods

1 - 3/16" aluminum ribs installed lengthwise inside the canopy side skirts to eliminate the overlap, provide exactly conforming skirt to fuselage alignment, rigidity, provide a straight line surface parallel with the canopy side tracks during full travel so they can be used for mounting a rubber airgap sealing surface. Great results.

2 - Plug on center canupy rail to eliminate hole in back when canopy is closed (T. Saylor idea). Great results but it has been a maintenance item as I evolve the best implementation.

3 - Extra fuel tanks carying 17 gallons of fuel. Great results got me home once already where landing with an electrical failure (solid state voltage regulator) with a LASAR ignition would have stranded me (they can't be hand propped).

4 - Center console containing the pitch trim control, two fuel control valves, aux. fuel pump switch, primer switch, four fuel filters, aux. fuel pump, primer solenoid and a route path for all wires and coaxes going aft of the main spar. Great ergonomics, cosmetics and functionality.

5 - Homemade fairings for all landing gear intersections and the horisontal stabilizer (cut off the originals and layed up the new ones right on the plane. Great the fit is perfect and the serviceability is excellent.

6- Lower cowl mod to reduce cooling drag and thereby increase speed. The first cut at is was a dismal failure with a 2 kt loss in speed even though it looks good and it took an incredible amount of detail work. I am continuing to work on it in hopes that I can turn it around but the jury is still out. Update: Success!! last modification picked up 6 kts which is 4kts better than the stock version performance!

7 - Relocated ELT antenna inside the bagage compartment to reduce drag. Great - Before I moved the rigid antenna inside with the end sticking up in the canopy bubble the antenna was being bent back by the wind so there was some force required to pull it through the air. No speed checks were made. It is way off to one side mounted on the flap actuator cover and loading and unloading bagage has not been a problem.

8 - Headrest for my wife mounted on the rear of the seatback crossbar. Great - let me count the reasons!

9 - Top forward fuselage skin extended 4" past top of instrument panel to form a glare shield, capped with a split 3/8" soft aluminum tube and covered with a split 3/8" rubber tube. Great for function and safe.

10 - Windshield defroster ported from the heater system and controlled by a extra manually controlled valve. Great when I have needed it a couple of times so far it worked as expected.

11 - Aluminum fresh air vent valves to replace the original black plastic units. Great - they actually work and increase the speed when closed.

12 - Aileron pushrod boots ped Ken Scott's article in Sport Aviation. Great - we no longer have to wrap the stick boots with a towel during winter flights at altitude.

13 - Contact paper used to produce race numbers. Great - they look good (like paint), conform to the surface and do not come off in flight but they are easily removable without paint damage after a race is over.

14 - Installed Tru Trak Pictorial Pilot and Altrak autopilot system. OUTSTANDING!

15 - Selected avionics and built up my instrument panel based on a barebones IFR requuirement (one Nav receiver with localizer and glideslope and an in-panel SL-60). One of my dumber ideas - I'm now looking at an GNS-480.

16 - Heavy weight aluminum tape on the leading edge of the sliding canopy. Great it holds up very well and looks great.

17 - Lighting in the wing tips (strobes, nav and landing) to reduce drag. Great - clean and very functional.

18 - Tracy Saylor Main gear and Van's nose gear fiberglass gear leg fairings in place of the glass wrapped wood and aluminum what were specified for my RV-6A. Great - never flew before they were installed so no relative performance data are available.

I have some other ideas knocking around.

Bob Axsom
 
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