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Upgrading the prop on my 4

thunder669

Active Member
So this has been in the works the last few months and with all the supply chain issues I have been waiting on parts but have been promised last one will be here next week. My 4 is currently setup with an O-360 A1A with a 72 x 87 Sensenich metal prop. I have always wanted to have a constant speed as I loved the extra capabilities it gives you. My previous plane was a Comanche 260 so was definitely spoiled with that.

Well I didn't want the weight penalty of a CS prop as I have worked hard putting my 4 on a diet and shaving over 20 pounds off of her since i got it. So I finally bit the bullet and got a whirlwind 3 blade CS. doing the basic math I should break even on the weight and with how much lighter my wallet is I should be way faster!!!!!

I plan to go up and do some basic Performance testing before I take her down to start the conversion and then repeat those tests afterwards and get some real world data. Can't wait to share the results with you guys
 
Looking forward to the results! I would like to make the same change.. is your firewall already notched for the governor? If not, you’ll have to pull the engine to make the modifications..
 
No the firewall isn’t notched yet, I did get the kit from vans and already assembled it so should go fairly quick.

As for the weight reduction this far I removed a very elaborate trim system and put in an electric one. Removed all the heavy gyros and put in glass panel and removed vacuum pump. Then removed a heavy Duracell lawn battery and put in an earth X battery. Overall reduction was more like 30 pounds but then added a smoke system
 
Don't forget when changing from F/P to a controllable prop, you must submit a new Airworthiness Application (FAA form 8130-6) to update records in Oklahoma City. This requirement is noted in your operating limitations.
 
It's getting closer and I am so excited!!!

engine is back in the plane after modifying the firewall and having our local A&P help me remove both plugs and install the new rear one. He said the rear plug in mine was the hardest he ever removed but after cleaning out all the sludge was quite happy with how clean the inside of the crank was and free of corrosion. I have installed the prop and the new vernier mixture control. still got some loose ends to tie up including painting the old mixture knob blue since that will now be the prop control. also have to safety wire a number of things but should be test running the engine this weekend and hopefully test fly first part of the week.

And Mel is correct and I did file my 8130-6 and also had a good chat with the head of our local FSDO. We are very fortunate that he is a longtime friend of our local EAA chapter and he is also going to help me update some things on my OP limits. I will have a 5 hour Phase 1 test flying period that I hope to fly off by next weekend and should be in good shape to take her over to Oshkosh.

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When I converted the RV-9A to constant speed prop, one significant change was the faster acceleration on takeoff. With a nosewheel, there was not much P factor and the increased acceleration was easy to handle. (The increased RPM on takeoff gave about 30 more horsepower.)

The other change was deceleration with the power back, and what that meant on approach and landing. You might be surprised what the c/s prop will do for you in that regard. I know that my RV-8, with constant speed prop and full flaps, would make a Cessna 172 with full flaps look like a sailplane. :)

Enjoy your "new" RV-4!
 
I talked to you 2 weeks ago at Marshall fly in, I have the RV8. I'm glad to see you're making progress with your conversion and I look forward to seeing you at future fly ins.
 
I am definitely looking forward to the braking action of the prop, that is definitely something I loved on my Comanche, especially when ATC would keep me high. I also look forward to seeing how it helps with the down lines on aerobatics.

It was awesome meeting you and getting all the info from you on the new prop. I greatly look forward to seeing you again and flying with you sometime
 
Before you took the -4 down for the conversion, did you document the performance you were getting? I want to do the 2 blade whirlwind, but I don’t want to take the plane down anytime soon..I would love to see pictures of the Firewall mod and maybe the engine plug swaps..
 
I did do some performance testing the morning I took her apart for the mod so will have a good comparison. there is a couple good threads on here of other peoples conversion that were extremely helpful. One was really well documented if i can find it again i will link it.
 
Your new prop looks awesome!! What is the linkage on your throttle lever that goes towards the back for?
 
WOW!!!!!! I have unfortunately had to work some extra hours so have only got to put 1.9 hours on the prop but man am I loving it. It took only one adjustment to the stop on the prop and governor was perfect out of the box. The acceleration is incredible and the braking action is equally impressive. She definitely launches down the runway and climbs like a rocket, and then was on an extended base at 180mph pulled the power and was down to 100mph quite quickly. Did a couple loops and half cuban 8's and speed is so much easier to control on the down lines. I hope to collect more hard data such as speed, climb rate and a few other things I tested before the swap in the next few days.

Also have to give a shout out to our local FSDO. The head guy there is a longtime friend of our EAA chapter and has already processed my 8130-6, and because of some discrepancies on my Operating limitations he has already issued me new ones so I just need to get a few more hours on her in the coming days and will be all set for flying her over to OSHKOSH!!!
 
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