Novel ideas that worked/did not work as expected

[Vern]

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?

[pierre smith]

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!!

[dan]

Pierre, have you tried that HS/elevator gap seal mod on your -6A?

[pierre smith]

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,

[hecilopter]

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!

[dan]

Originally Posted by pierre smith

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.

[pierre smith]

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?

[pierre smith]

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

[pierre smith]

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,

[DeltaRomeo]

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.

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