Through my connections here at work I get to meet a lot of vendors and I found one that might be able to get us set up with a prop.
It would be an electrically controlled constant speed propellor. They can easily help us with the 6 bolt hubs and I am working with them on the 8 bolt series.
The performance gain for the dollar should be quite impressive. To be able to use 2700 RPM for Take-Off and then set up a cruise scenario is exciting for me.
With the new prop, controller, and spinner and an additional change for an STC to come the cost would bearound $9000, plus you could sell your old prop for $1500 or so. It would also work on all the early 172's as well.
When comparing this to the cost of the 180, 210, or 220 HP (30-35K) conversions it seems to be cheap plus we get to keep our lower fuel burn which pays off big in the long run.
Anybody want me to start pushing?
Constant Speed for O-300 possible
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
That's good news, Kelly. But it's a tough call to make--nine grand is a lot of cabbage! Then again, it's dirt cheap compared to installing a bigger engine. It all depends on what the actual performance gains will be, I guess.
I'm curious also about what prop/governor? I know a guy who had an electric Ivo prop on his Velocity (aka "the boomerang"), he had some trouble with the composite blades de-laminating. he ended up putting (I think) an MT prop on. But he has an O-360 Lyc so it has provisions for a regular hydraulic C/S.
I wonder if a controllable variable-pitch prop might be a better choice, versus a constant speed? I'd think it would be lighter & simpler, and less prone to malfunctions. I don't have any experience with them, though, so I'm just guessing.
What kind of weight increase are we talking about versus the standard fixed pitch? Way out there on the nose, it wouldn't take much weight increase to really affect the CG. Could always move the battery aft, if necesary I guess.
I'd like to see you pursue it with your vendor. I don't think any of us are against an affordable performance increase, except maybe with regards to originality. Just a matter of cost versus actual benefits.
Eric
I'm curious also about what prop/governor? I know a guy who had an electric Ivo prop on his Velocity (aka "the boomerang"), he had some trouble with the composite blades de-laminating. he ended up putting (I think) an MT prop on. But he has an O-360 Lyc so it has provisions for a regular hydraulic C/S.
I wonder if a controllable variable-pitch prop might be a better choice, versus a constant speed? I'd think it would be lighter & simpler, and less prone to malfunctions. I don't have any experience with them, though, so I'm just guessing.
What kind of weight increase are we talking about versus the standard fixed pitch? Way out there on the nose, it wouldn't take much weight increase to really affect the CG. Could always move the battery aft, if necesary I guess.
I'd like to see you pursue it with your vendor. I don't think any of us are against an affordable performance increase, except maybe with regards to originality. Just a matter of cost versus actual benefits.
Eric
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Bruce Fenstermacher
- Posts: 10320
- Joined: Tue Apr 23, 2002 11:24 am
I've had this conversation with a prop manufacturer who was in the process of building a prop to squeezing another 10 or 20 knots out of a Lancair 4P.
The way his prop would work is the composite blades would twist flat as engine power was applied. The total flatness would be controlled by the composite material used. Electrical power would be applied to the blades and this would increase the stiffness not allowing them to twist against the power applied thus you would have a variable pitch prop with no moving parts other that the brushs used/mechanisim used to transfer the power from a stationary point to the rotating prop. Apparantly this technology is available today. At least that is the way I understood it.
He said if he would persue it it would take about 2 years to fully develop and certify.
I asked him why he hadn't done it for the regular guy. Think of all the Cherokees and 172s and of course our 170s out there that could be in the market.
He said it probably would never be done. Why? Because very few people with a $40,000 plane would spend $10,000 and he'd have a hard time recouping his development money. But he'd spend a whole lot less time and money perfecting his Lancair 4P prop and sell a few of them for $20,000 a piece to guys who don't mind spending $250,000 to $500,000 for their plane.
Don't get me wrong I think it would be a GREAT idea and someday someone might do it. I can't say I'd be able to buy one for $10,000 but I could dream about it and I'd probably opt for it over a 180 conversion.
The way his prop would work is the composite blades would twist flat as engine power was applied. The total flatness would be controlled by the composite material used. Electrical power would be applied to the blades and this would increase the stiffness not allowing them to twist against the power applied thus you would have a variable pitch prop with no moving parts other that the brushs used/mechanisim used to transfer the power from a stationary point to the rotating prop. Apparantly this technology is available today. At least that is the way I understood it.
He said if he would persue it it would take about 2 years to fully develop and certify.
I asked him why he hadn't done it for the regular guy. Think of all the Cherokees and 172s and of course our 170s out there that could be in the market.
He said it probably would never be done. Why? Because very few people with a $40,000 plane would spend $10,000 and he'd have a hard time recouping his development money. But he'd spend a whole lot less time and money perfecting his Lancair 4P prop and sell a few of them for $20,000 a piece to guys who don't mind spending $250,000 to $500,000 for their plane.
Don't get me wrong I think it would be a GREAT idea and someday someone might do it. I can't say I'd be able to buy one for $10,000 but I could dream about it and I'd probably opt for it over a 180 conversion.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
You're right about that, Bruce! Composites require specialized repairs.
The old Beech-Roby electrically adjustable prop was obsolete by constant-speed standards. It had a toggle switch in the cockpit that allowed the pilot to increase or decrease blade pitch within certain limits. Typically, the minimum pitch would result in max engine rated rpm, and the pilot would select that for takeoff. Afterwards, the pilot could set his throttle and select the prop pitch that gave him a desired rpm. Of course, any throttle change made a corresponding rpm change since the prop pitch was unaltered except by that toggle.
A later electronic-type control box was offered, which had a rheostat which kept the prop within a narrow rpm band, similar to a constant speed.
Either system would interest me, provided it was an all-metal prop, and could use a spinner that wasn't the size of a church-bell.
The old Beech-Roby electrically adjustable prop was obsolete by constant-speed standards. It had a toggle switch in the cockpit that allowed the pilot to increase or decrease blade pitch within certain limits. Typically, the minimum pitch would result in max engine rated rpm, and the pilot would select that for takeoff. Afterwards, the pilot could set his throttle and select the prop pitch that gave him a desired rpm. Of course, any throttle change made a corresponding rpm change since the prop pitch was unaltered except by that toggle.
A later electronic-type control box was offered, which had a rheostat which kept the prop within a narrow rpm band, similar to a constant speed.
Either system would interest me, provided it was an all-metal prop, and could use a spinner that wasn't the size of a church-bell.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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funseventy
- Posts: 230
- Joined: Fri Oct 25, 2002 11:46 pm
I feel I have the talents and the friends with other talents to be able to push this through for relatively low cost but it will cost more calendar days as a result. The initial cost for the first prop is low enough to make me think I could do it.
The performance is unknown until installed and flown but I would expect somehing halfway between what we have and what the O-360 has.
We have some options for composite or aluminum but it would be a certified installation. From the sound of it if you went the composite direction the net increase in weight might be negligable. I will keep pursuing.
The performance is unknown until installed and flown but I would expect somehing halfway between what we have and what the O-360 has.
We have some options for composite or aluminum but it would be a certified installation. From the sound of it if you went the composite direction the net increase in weight might be negligable. I will keep pursuing.
"Either system would interest me, provided it was an all-metal prop, and could use a spinner that wasn't the size of a church-bell."
George, I know what you mean about those big church bell spinners, heres a picture of a friends airplane that has one. Lots of momentum there once you get it turning
Johneb
George, I know what you mean about those big church bell spinners, heres a picture of a friends airplane that has one. Lots of momentum there once you get it turning
Johneb
Last edited by johneeb on Tue Jan 11, 2005 1:56 am, edited 1 time in total.
CS ? Prop
I'll have to add my DITTO's to the other guys. Sounds like something a lot of us tail end charlies have been looking for. However if everyone got one of these props then my ole tub of bolts (and rivets) would still be slower wouldn't it? Seriously I will be really interested in the development process of this idea.
Please keep us up-to-date on your progress.
Please keep us up-to-date on your progress.
OLE POKEY
170C
Director:
2012-2018
170C
Director:
2012-2018
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BloomerJohn
- Posts: 55
- Joined: Mon Apr 22, 2002 3:28 pm
I am in business with one of the two US Sales Representitives of MT Propellers (Germany). I will ask Larry about the electric CS they make. If one of tested design from a strong and experienced mfr is avail for the cost of the STC, it should be investigated.
BTW, The MT natural composite 4 and 5 blade CS are the props of choice for the 4P (I am helping my hangermate build one)
BTW, The MT natural composite 4 and 5 blade CS are the props of choice for the 4P (I am helping my hangermate build one)
why not just thin out the pitch on your fixed pitch prop if you want more turns for take off? If you want the airplane to cruise at a certain speed, it requires the same horsepower regardless of the RPM. The engine has a certain specific fuel consumption and the only difference in fuel consumption at a given power at different RPMs is the difference in pumping and friction losses.
My fifty inch prop gives a lot more wallop for take off and climb than a standard fifty three inch cruise prop and when I cruise at twenty six hundred abd fifty RPM my fuel burn at the end of four hours is almost exactly the same as when I had a fifty three incher.
I sure wouldn't hold my breath waiting for someone to develop and certify a prop for fifty year old airplanes. With about thirty five thousand C-172s having been built, plus the C-170s, I'd bet that one of the prop manufacturers probably thought about that potential market and decided just like Cessna. KISS! The new C-172 is up to 180 HP and I believe they're still using a fixed pitch prop.
You have to realize that we're involved in somewhat of a "cult" airplane and are much more passionate about our trusty steeds than the average C-172 operator. I dont believe many of them would be even a little bit interested in spending that kind of money. They would move up to a C-182 first. And if I flew a C-172, so would I.
My fifty inch prop gives a lot more wallop for take off and climb than a standard fifty three inch cruise prop and when I cruise at twenty six hundred abd fifty RPM my fuel burn at the end of four hours is almost exactly the same as when I had a fifty three incher.
I sure wouldn't hold my breath waiting for someone to develop and certify a prop for fifty year old airplanes. With about thirty five thousand C-172s having been built, plus the C-170s, I'd bet that one of the prop manufacturers probably thought about that potential market and decided just like Cessna. KISS! The new C-172 is up to 180 HP and I believe they're still using a fixed pitch prop.
You have to realize that we're involved in somewhat of a "cult" airplane and are much more passionate about our trusty steeds than the average C-172 operator. I dont believe many of them would be even a little bit interested in spending that kind of money. They would move up to a C-182 first. And if I flew a C-172, so would I.
BL