John Slade

Two thoughts on noise: 1. Much of the noise you hear in a pusher is wind noise 2. The rest is basically engine noise and vibration. Those who had a Lcyoming, then installed a Rotary (eg Tracy Crook) have told me that the difference in noise and vibration is very significant. Tracy said that a 3 hour trip used to leave his teeth rattling and his ears ringing. Now it's a much more comfortable ride. One RV builder I met was in the process of removing a Lycoming 320 and installing a 13B following one trip in Tracy's plane.

Jon, Why not add this as a link from the main page so people can find it?

I know you were joking, Jon, but I want to say something anyway... This is about information and camaraderie(sp?), not loyalty to a particular medium of exchanging or sharing it. I WISH I could get all my info from one place, and I WISH that place was a forum type format, but right now I have to monitor the Cozy list, the ACRE list, the fly-rotary and the aeroelectric list. Some of the information is not type specific - rotary / electric - so I cant expect people like Ed Anderson or Tracy Crook (RV rotary flyers) to come over here. Eventually, perhaps they'll go to homebuiltairpanes.com or homebuiltaircraft.com, and maybe we'll integrate with one of them, but I doubt that'll happen soon. Just trying to look to the future. John

This was another very short day. The [house] AC broke and I had to wait home for the repairman. Don't cry for me, you Northerners. On top of that today is Char's birthday, so she got some special attention. Gotta keep the GIB happy! I managed just 2 hours on the plane. I got the ordering done, but didn't make it up to the hose shop or the breakers yard. I did sand the cowl exits and cowl door some more and now have the whole cowl pretty much ready for primer. Yes, it HAS been gloss painted once. Since then it's had 2 doors added and the rear exits modified. Perhaps I painted too early. Anyway, I'm rubbing it down and will paint it again, along with a few other areas on the fuselage that need attention. I'd previously run a 22 gauge 3 pair color-coded teflon wire from the engine compartment to the panel, so hooking up the water temp, fuel pressure and air/fuel ratio sensors to the gauges was a very simple 30 minute job once I found the wiring diagrams. Tomorrows plan: Get smog pump fitting from hose shop Get washer for turbo water union from hose shop Look in breakers yard for a smaller compressor wire smog pump to a switch - where to put the switch??? wire alternator idiot light work on fitting compressor

Paul Lamar and a few others from the ACRE list have been working on an adjustable prop design. I think they have the prototype ready for testing on the dyno. It's taking a long time, but it might bear fruit eventually.

Note for those following this thread: Rather than upload images here I've made a web site page at http://kgarden.com/cozy/launch.htm which I'll update once / week or so. The web page contains the text from the forum a few days behind, expanded here and there as I think of new stuff, and with a few pictures to help clarify things.

Backordered? How can this be? Spruce physically collected hundreds of sets of plans from Nat in December. Is it possible that they've canned all these copies and are reprinting the entire set to remove Wicks from the supplier's list?

The following was posted on the Aeroelectric list this morning. It is important for anyone installing an automotive alternator. In general, I'd suggest that subscribing the Bob Nuckoll's list and getting his book is an essential part of the learning curve if you plan to wire you're own airplane. __________________________________________________________________ --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net> As promised, I've been looking into this problem and I've crafted a white paper on the topic. Here is the text of the paper . . . ------------------------------------------- "Load Dump" Damage to Alternators with Built-in Regulators Bob Nuckolls 1 February 2004 >AeroElectric-List message posted by: "Ned Thomas" <315@cox.net> > >For what it is worth, I had an internally regulated alternator >on my RV6A. I had an overvoltage occur and had no way to >shut it off except land and turn off the engine. When >I smelled the battery acid cooking out I was quite concerned. >I was able to land before ruining the battery but even tho >I immediately turned off the master when I found the >voltmeter reading high, I did find that one of my strobes >had fried. After this happened I installed the OV protection >recommended by Bob. In the event you do encounter an OV >situation you must be able to isolate the alternator. >I was lucky, the battery could have blown up... >----- Original Message ----- >From: "Clay R" <clayr_55@yahoo.com> >Now I see the following warning on Vans web site on >the alternator page. (I think this was added this week) >Warning! >The internally regulated 60 ampere alternator should not >be used with overvoltage protection systems. If you >open the charging circuit while it is in operation, >it will destroy the regulator. >AeroElectric-List message posted by: "Steve Sampson" <SSampson.SLN21@london.edu> Clay - is anyone looking into this for you? It sounds >like plenty of people are getting blown alternators >after putting the B&C stuff on. BACKGROUND (1) The "B&C stuff" is only a collection of parts described in documents described in the AeroElectric Connection. Let us take care as to how the phenomenon is described with respect to implied cause and effect. It's not B&C's architecture but AeroElectric Connection architecture . . . B&C only sells the parts to implement it. (2) For years and since day-one of my participation in B&C's development and marketing of alternators, we have preached the doctrine of externally regulated alternators. Examples of this philosophy are found throughout early writings and particularly in chapters on alternators and regulators in the 'Connection. A simple inspection of B&C's offerings from the beginning will show that only externally regulated alternators are offered. (3) There has been a lot of interest in adapting internally regulated alternators to aircraft because they are so readily available and cheap. Further, they've produced an excellent track record of reliability on cars . . . it seems a shame not exploit that characteristic in aircraft. (4) The challenge for adapting internally regulated alternators to airplanes has always been making them behave like externally regulated alternators and generators before them. On the instrument panel there is a switch labeled ALT OFF/ON. One expects that operation of this switch will produce the same result whether you're sitting in a 1965 C-172 or a 2004 RV-8. (5) Most alternators with built in regulators, once given the ON command via the rear-connected control wire will indeed come alive . . . but since this wire was originally intended only as a means for the EFI controller on a car to delay onset of engine loads after starting, there was no requirement for being able to turn the alternator OFF via this same wire. So, the vast majority of automotive take-offs cannot be turned OFF by removing +14v from the control wire via panel mounted switch. This condition was experienced by Mr. Thomas in the anecdote cited earlier. (6) While the probability of regulator failure in cars is exceedingly low, it is not zero. We've heard anecdotal stories of unhappy, high-dollar events taking place in airplanes after failure of an internally regulated alternator. (7) With the goal of addressing a desire in the marketplace to utilize off-the-car technology, figure Z-24 was developed to address both controllability and overvoltage issues with the lowest practical parts count and without modifying the alternator. RECENT HISTORY It seems that there have been a rash of failures of internally regulated alternators installed per Figure Z-24. Let's review the inner workings and shortcomings of the modern, internally regulated alternators. We know that all alternators run best with a battery connected across their output. The battery is an excellent filter for the noise inherent on DC power generated by rectified 3-phase AC power. The battery also provides a flywheel effect . . . a kind of electrical inertia that damps out the frisky nature of an alternator's ability to quicky respond to and control its own output. A phenomenon labeled by the automotive industry as "load dump" speaks to a characteristic native to the physics of alternator performance. Its existence has been known since the beginnings of alternator use in vehicles . . . but it was only a concern after a proliferation of solid state electronics for fuel injection systems, ignition systems, anti-lock brakes, etc. Should an alternator producing a lot of power be suddenly disconnected from the load, it may generate what would be properly called a surge of voltage exceeding bus voltage by several times. If the load dump is limited to shedding of normal system loads, the battery's electrical inertia will be in place to smooth over the event. However, if the disconnection includes the battery, no mitigating electrical-mass is present to capture a significant energy transient. In aviation parlance, a "load dump" is rapid shedding of normal system loads. The scenario we are discussing might be more appropriately called a "battery dump". Unlike relatively low energy spikes characteristic of switching transients on inductive loads, a battery dump event is longer and carries a lot more energy. In the spring of 1998, there was a romance in the OBAM aircraft community with products called transient voltage suppressors (TVS). A school of thought suggested that the electrical system be sprinkled with these little critters to ward off effects of any gremlins of the overvoltage persuasion which may be lurking about the system. The suggested technique was to install a TVS on the power feeder for each vulnerable accessory. There was an extensive discussion thread. You may review published excerpts of that discussion at: http://aeroelectric.com/articles/spike.pdf This was before we began to consider and refine any notions of using internally regulated alternators in OBAM aircraft. In that thread, I suggested it was much better to (1) identify and mitigate such hazards at their source and/or (2) design accessories to be immune to such hazards. For decades, DO-160 has been an effective guideline for development of robust victims while MIL-STD-704 outlined design goals for output quality of power generation equipment. Here are but a few of hundreds of relevant documents on the phenomenon to be found on the web . . . http://www.sto-p.com/pfp/pfp-transients.htm http://www.onsemi.com/pub/Collateral/CS3341-D.PDF http://www.audifans.com/archives/1998/08/msg00929.html . . . do a Google search on "load dump" and "alternator" for a wealth of useful expansion of the topic. WHAT'S HAPPENING? The original discussions 4 years ago focused on the need to protect system accessories from the effects of alternator behavior. In the cases before us now, the victim is NOT airframe system accessories being hammered by a skittish alternator. These are cases where the alternator is killing itself . . . or more accurately, killing its own voltage regulator. If you look over the specifications for modern, solid state regulator chips, you'll find references to protection against load dump conditions built right onto the chip. I believe what we're observing now is a shortcoming of relatively mature automotive take-off alternators with regulators that do not enjoy this kind of protection. Referring to the group of block diagrams in this document, note that I've illustrated 4 configurations of installation architecture for alternators with built in regulators. (download http://www.aeroelectric.com/articles/Alternator_Failures.pdf to get the illustration) (1) The first diagram is captioned "AUTOMOTIVE" and it illustrates the relationship between battery and alternator in virtually all automotive applications. The battery is ALWAYS connected to the alternator. System loads are controlled via panel switches and/or ignition switch but portions of the power distribution system are always hot, even when the vehicle is parked. Not desirable on airplanes. (2) The second configuration is "FIGURE Z-24" referring to an architecture described in the AeroElectric Connection to accommodate two hard-and-fast design goals for using an alternator in an airplane: (a) absolute control of the alternator operation from the cockpit irrespective of flight condition and (b) protection against the very rare but potentially hazardous and expensive overvoltage condition. (3) The third configuration describes an ill-conceived recommendation suggesting deletion of the alternator disconnect and wiring the alternator to the airplane a-la-automotive. Note that while this configuration prevents the pilot from switching an alternator off while in operation, it does not prevent the battery from being taken off line. If we disconnect the alternator from the system while leaving the battery on as allowed with Figure Z-24, only the alternator is at-risk for self destruction. When you leave the alternator connected to the system and shut off the battery master, there is still risk of a battery-dump transient. While system loads will soak up some transient energy and mitigate amplitude and duration of the event, now the whole system is subjected to the transient. In airplanes like the Baron and Bonanza where alternators and battery master switches are separate, non-interlocked controls, switches can be manipulated in a manner that will produce the same "battery dump" effect that we're discussing. So the potential for this effect is not new nor is it unique to the nifty little alternators so popular in the OBAM aircraft community. (4) The fourth configuration illustrates an experiment to be conducted which may prove the usefulness of a technique intended to tame the dragon. A PROPOSED GAME PLAN (1) If you have Figure Z-24 installed and you're already flying or nearly ready to fly, don't change anything. Although you may never need the protections Z-24 offers, I don't recommend you go flying without it. It is EASY to prevent battery dump damage to the alternator by controlling sequence of operation for the switches. [a] Battery master is the first switch to come on before cranking the engine and it should stay on until after engine shutdown. The alternator control switch may be turned on before cranking the engine but it's probably better to leave it off until after the engine is running. [c] At the end of the flight, shut the engine down before first turning off the alternator . . . . [d] . . . followed by turning of the battery master switch. Following suggestions in any of the Z-figures in the 'Connection will provide you with interlocked battery master and alternator control switches wired so as to prevent an alternator from remaining on-line with the battery disconnected. The battery dump transient is generated by the disconnection of the battery from the alternator b-lead terminal while the alternator is working hard. It can't be working hard if the engine is not running. The warning published by Van's is accurate as far as it goes but misses important points with respect to absolute operational control of the alternator from the cockpit and overvoltage protection. So, if you don't diddle with the switch while the engine is running, your alternator is not at risk for battery dump damage and you retain both operational control and overvoltage protection. (2) If you have yet to select an alternator but need to do it soon, you cannot go wrong with installing an alternator designed for aircraft service. Alternators using external regulation are easily managed for both operational control and overvoltage protection by simply opening the field lead. This activity does not generate the battery dump transient we're discussing. (3) I'm planning to test an alternator with built in regulation on a test stand using a fat TVS device connected as shown in the last block diagram. I'll be making measurements of worst-case transient energies and making sure that the diode we select is adequately sized to the task. NOTE If anyone out there remembers the zener diode that Pelican Aviation used to stick on the back side of their alternators (some STC'd no less!) while calling it "overvoltage protection" please recall that this was neither ov protection nor was it a practical solution to the problem before us now. After the bench testing studies are complete, I'll be looking for volunteers who are already flying Figure Z-24 alternator control schemes. I will supply a pair of TVS diodes for installation on your airplane. You will be asked to conduct a series of battery dump simulations. After the simulations, you'll be asked to install the second diode and return the first one to me for inspection. Once we've done the repeatable experiment to demonstrate suitability of the "fix", this paper will be updated to publish the results and Figure Z-24 will be updated appropriately. In the mean time, I'll supply a copy of this paper to Van's in with the hope that it will clarify the issues and forestall some poorly founded modifications to electrical systems in the OBAM aircraft community. Please feel free to circulate this document for both its informative value and potential for critical review. As a closing note to this document, I ran across this paper: http://www.st.com/stonline/books/pdf/docs/4345.pdf . . . written by the folks at SGS-Thompson on battery dump mitigation. This paper describes a proposed technique for building battery dump management right into the alternator . . . what a concept! Whether or not this capability will be offered in automotive products suited to airplanes soon is hard to predict. In the meantime, it's a no-brainer to make the alternators we have work quite nicely. The bottom line folks . . . I believe there is good value in the use of internally regulated alternators on airplanes. However, it's important that we make decisions based upon good science that helps us understand and accommodate their unique characteristics. Bob . . . _-======================================================================== _-= - The AeroElectric-List Email Forum - _-= This forum is sponsored entirely through the Contributions _-= of List members. You'll never see banner ads or any other _-= form of direct advertising on the Matronics Forums. _-======================================================================== _-= !! 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The day started a bit late and ended a bit early. I did the following: Sand and remicro cowl exits - almost ready for primer. finalize exhaust shroud fit - I'm pleased with the new look. Test smog pump clutch - works fine. Test fan wiring - replaced bad crimp. Wiring is good. Didnt do: wire smog pump to a switch wire air/fuel ration sensor wire water temp sensor wire alternator field But I did install the cowl door latch and hinge. Total - 3 hrs Plan for tomorrow: Order 9 * 9 100 4031 steel sheet for brackets Order more BID Get smog pump fitting from hose shop Get washer for turbo water union from hose shop Look in breakers yard for a smaller compressor wire smog pump to a switch wire air/fuel ratio sensor wire water temp sensor wire alternator field

The pump v scale thing has been heavily discussed. I'd recommend a pump, others a scale - but no one I know recommends the plans balance. The volt thing - better to use the voltage regulator from Wicks. Worth the money. The wire burner - Look in Cozy mail list archived for design ideas. Mine was pretty much per plans and worked well. You wont need this till Chapter 10.

My '89 Saab 9000 Turbo has heated seats, but I dont use them much down here in S FL. If you can find a Saab 9000, or perhaps even a 900 in a breakers yard perhaps you could remove the heaters.

In the RAF we had a monthly internal periodical with a centerfold "Accident of the month". Excellent reading. My instructor was featured three months in a row.

Definately. I don't know that a lot was achieved, but that's not the point, is it. I think we should do this weekly, ideally with chat software built in next time. Once in a while we could invite "guests" to join us. Maybe one day, Nat, or even Burt himself will drop in. In the meantime I'm trying to think of interesting people we can invite. For example, my hangar owner is Paul Mason of VariEz racing fame. A facinating guy, but I'm not sure how fast he can type. Another hangar mate, "little Al" is a CFII, flys a LongEz and a twin turboprop for his day job. I'd like to have a few Cozy flyers join in. Norm Muzzy, perhaps, Dave Domier, Greg Richter.... Suggestions welcome. Bring you're friends.

I don't know if this countdown thing is helping anyone else, but it's sure helping me. It's easy to get overwhelmed and in a rut when working on a job of this size and complexity. I was getting stuff done, but didnt seem to be making any real progress. If you don't set targets, then you won't meet any. Now I have a target, and I'm motivated to meet it. OK. The plan for today was: Reassemble and install smog pump Install and tension alternator belt Install vacuum regulator and vacuum pipes When I got to the hangar I dived in to cleaning up the cured layup on the rear of the cowling. When the clay was all gone I laid up another 2 ply BID on the inside curve. I moved the exhaust shround to the other side, reversed it to get an identical curve the other way and did the modelling clay thing on that side too. I fiddled with the smog pump for a while, but decided that removing the clutch would require an properly engineered center for the replacement pully. I decided to defer this issue and just mount the pump as-is. I have the tension bracket already made so installing the pump was a breeze. I've been trying to decide where to mount the vacuum regulator. The ideal place would be on the firewall above the aileron torque tube, but this would mean drilling through the spar, and would take up room I want to use for the overflow bottle. In the end I decided I could mount it right on the smog pump with a 1/2 NPT to 3/4 npt 90 degree fitting. This will also save me a hose and a pair of connectors. The regulator will be hanging off the smog pump, but it's made of steel, so I dont see a problem with that. I tensioned the belt, but then had to take it off again to remove the incorrect hose fitting. This evening I went down to the hangar again, cleaned up the second set of layups on the cowl exit holes and microed them so they'd be cured ready for sanding tomorrow. Total time 8 hrs. Plan for tomorrow. Sand and remicro cowl exits finalize exhaust shroud fit Test smog pump clutch and wire it to a switch Test fan wiring wire air/fuel ration sensor wire water temp sensor wire alternator field Plan for Monday Order 9 * 9 100 4031 steel sheet for brackets Order more BID Get smog pump fitting from hose shop Look in breakers yard for a smaller compressor.

This should be over in the computer ettiquette area, but I'll post it here for now. I'm hesitant to move stuff around too much after making Jon piss himself last night. (he's concerned that the current forum setup is a bit buggy and fragile). >Someone help me please .... Let me see if I can get this across, Jim... You and I are good friends. We know each other well. If we go in a bar and have a lively conversation you'll tend to "puntuate" what you say with 4 letter words. You know me, and you know it won't offend me because I usually come right back with equally colorful language. Now lets move the scene to dinner at a five star restaurant with our wives. Out of respect for the ladies, or neigboring diners, we might tone it down a bit. Then, on the other hand, we might not. Now imagine that a third couple joins us. People we don't know. Rather than risk offending them, we'd probably cut the language way back out of politeness until we know them a little better. Remember the Officer's Mess? The problem with internet communications is that you never know who you're talking to. That third couple is lurking all the time and might be offended. The occasional curse helps with emphasis and probably won't offend most people. However, using p.ss or sh.t in every fu*king message is just a bit over the top. Oh - why the dots. To get around the censors, which we haven't switched on, but perhaps should. Does this help?

>I would suggest that it's never a single failure. There are plenty of single failures that'll spoil you're day. Catastrophic engine failure, prop failure, structural failure etc. But, there are usually additional factors that make it worse. I think of this as the three things rule. It usually takes three things to go wrong together to hurt you. e.g. Lets say prop failure occurs. If you're on the ball, have some height and have a field picked out, then you'll probably be ok. (sound familiar?) If you were buzzing a friends house at the time (error 2) and not really thinking about relief landing fields (error 3) you could be in big trouble. Almost every accident takes three things

Absolutely! Other Vbulletin users must have the same need, so I'd bet there's an add-in available. If it costs something I'm in for a few $ to help pay for it.

Yea, guys. Take it to the PM

Day 30 Yesterday I cut off the lower pipe from the cast water pump housing and adjusted the angle to allow it to miss the alternator belt (which is running lower than stock because I lowered the smog pump to get it under the cowl. I left it with Charlie to weld the piece back on at the new angle. Today I collected the newly welded water pump housing and installed it on the engine using Ultra-grey and the stock manifold gasket. I installed the water pump itself, then disassembled the smog pump to see how easy it might be to remove the clutch and have it run without having to energize it. It doesnt look easy, so tomorrow I'll probably reassemble the clutch and install the smog pump as is. Tonight I'll ask in the flyrotary list in case Ed (he's also using the smog pump for vacuum) knows how to do this. I duct taped the exhaust shroud, installed it in the cowling, then used modelling clay to make 1 inch curved forms between the shround and the cowl for a layup. Right now my exit holes are simply cut out of the cowl shape. I'm adding a short (2 inch) tube at each cowl exit hole for the exhaust shroud and intercooler exit ducts to ride in. Pictures will make this clearer shortly. I layed up 2 BID tapes over the clay forms onto the cowl and duct taped shroud. I also duct taped the new cowl door I've cut at the front of the cowl for checking coolant levels. I layed up a 2 BID lip on the inside of the cowl around the new door. Total time 3 hours. Plan for tomorrow. Reassemble and install smog pump Install and tension alternator belt Install vacuum regulator and vacuum pipes

OK. It's time to put myself on the line and set a target for first flight. This will help motivate me (being accountable like this) and might be of interest to others. So what's the target. Leap year day, of course! So. This is day 30 and counting. I have absolutely no idea whether I'll make it or not, and I'm sure not going to compromise safety, but a target is a target, and I'll shoot for it, work permitting. What do I have left to do? Well there's a list on my web site http://kgarden.com/cozy/things.htm but its not very detailed and most of what I do each day isnt even on it. In addition to the list over there, here's whats needed: Finish exhaust shroud install (curing as we speak) Reassemble and install smog (vacuum) pump Deal with the smog pump clutch Mount the vacuum regulator plumb the vacuum firewall backwards install the AC compressor plumb the AC firewall backwards (this is a bear) install lower cowling plumb turbo > intercooler > throttle body wire a bunch of sensors replace throttle cable bracket with steel figure out a way to install hobbs sensor weight and balance engine start taxi test etc. (big etc) inspection first flight. I'm probably missing a bunch of minor items, but these are the big ones. All moral support, comments , questions and cheerleaders welcome. Day 30 progress report will follow.

The hot tub is open. See the new section on the main menu.

Cool, Steve. That puts you EXACTLY 4 years 11 months behind me. I hope you have as much fun in the next 5 years as I had in the last 5.

The day control of who's an "approved" supplier and who isn't passed to one of the vendors the meaning of the word "approved" was completely devalued. "authorized and approved" no longer have meaning with respect to Cozy parts, except with respect to things you can ONLY buy in one place and can't make yourself. The only material that kinda fits into that catagory is spar cap tape. Gear struts can be got from 2 suppliers. Canopies can be got from 2 suppliers. Hardware can be made from plans drawings. Wicks is still there competing with ASS on the basic supplies, as are numerous other vendors. I don't see the problem

Works for me. Maybe we can get the Cozy Girrls, Chrissi & Randi to join us. http://www.cozygirrrl.com/ People can download a cheeshecake shot of Randi from their web site at http://www.cozygirrrl.com/randicheese.htm For anyone who hasn't met the Girrrls, they're a real trip. Smarter than the average Joe (or Jane) by a long way, and full of interesting ideas. I beleive that they're 13B retractable Cozy IV is making good progress. PS - Steve - bring you're wife.

>stall proof design decides the size of the canard, and thus they rotate later Not necessarily. Take off distance is a function of acceleration. When you get to flying speed you fly. Greg Richter (turbo 13B cozy III) told me a little story when I visited him. He'd flown his own plane a few time and said that when you opened the throttle you got a push in the back like you were flooring the gas in a Porche. He had someone standing by the runway, and his take off run was VERY short. After 2 or 3 flights he decided he'd like to get some dual, so he found a nearby 360 Lycoming powered Cozy IV and an instructor and went flying. He opened the throttle on his first take off roll. Part way down the runway he throttled back and aborted the take off. The instructor asked "what's wrong". Greg felt there was something wrong with the engine. "Nope", said the instructor. "Its running perfectly". The point is that the difference in acceleration between the two planes was so dramatic that Gregs first reaction was that the Lycoming wasnt going to fly. Greg is a member here, but he's probably too busy with http://BlueMountainAvionics.com and his new jet turbine installation to spend much time chatting. As they say - there are those that do, and those that talk. Right now I'm just talking. If I got the story wrong, I hope he'll correct me. MT - I know you chatted with Greg. Did you discuss his take off performance? Recently I heard that Hartzell had announced that their $15k constant speed prop had problems at certain rpms on Velocities. Again, someone can fill in the details. Yes, if you read the NTSB report, which I did recently, you'll see that the Velocity IVO pilot had a prop problem, landed, stripped it down and reassembled it himself, failed to torque it properly and then set off again (with his two daughters) without following the prescribed tests, for an appointment with a tree. My thoughts on the prop was to go for max cruise speed 3 blade wood prop. My prop was designed for 280HP and 250mph cruise on the basis that it can easily be cut back, but cannot be tweaked up. I think I'll have enough spare power to take off in a much shorter distance than a stock Cozy, and climb faster even though my prop is not optimum for those flight areas. Unfortunately, extra horses on board dont help you land any shorter , so you still need a long runway to operate from.