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Engine Choices - 1500 lb GW/1650 lb w/Floats

RAVC1

MEMBER
Southeast Michigan
I have an opportunity to purchase the complete raw materials for an E/AB side-by-side 2-seater and I'm finding my desire to install floats is creating a problem that makes me wonder if I need to abandon the idea of floats or this aircraft. We must begin this effort with an aircraft with low operating costs. We also plan to help our son build a larger aircraft later. My desire to use the aircraft primarily over undeveloped terrain caused one auto engine conversion manufacturer to recommend I use exclusively an aviation engine. The problem is that he also suggested I put and O-320 in the aircraft. Nice engine but it's too heavy. I do not like the idea of reducing useful load because if this aircraft happens for us it will be a working family airplane so I do not want to reduce its capabilities.

After seeing this footage of a Catto on a TCM A65 I was hooked on Catto.

I have also seen footage of a Cessna 150G w/O-200 on floats and the performance was understandingly lacking. For this reason I do not see a modified C-90 or O-200 as suitable.

If we consider the empty weight of the aircraft to be 800-850 what would you suggest or recommend for an engine that will meet my needs? Here are a few I have thought of:

Franklin 4A-235 - 206 dry weight (fuel spec is a concern)
TCM IO-240 - 255 dry wt.
Lycoming O-235 - 240 dry wt.

I was looking forward the the ECI 4-cylinder but have no idea what the status is of this engine program. Are their others? I really think I need more thrust than any of these engines in view of the desire for floats.

How valid are engine building issues like reducing reciprocating weight, balance, airflow, etc. with these engines. I certainly know of Lycon but are they really the only company that has a sound reputation with these skills?

Weights: Wife + me ~ 265 pounds, Son + me = 282, Wife + son ~ 250

Let me know if you have questions.
 
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My J4 with a 85 stroker works very well as a 2 up float plane, has even been at 1600lbs once. As does my buddy with a Chief with a 85 stroker

Glenn
 
The first thing is tell us about YOUR flying history!! What type of aircraft and how many hours. I ask this because some think they can get by cheap and that is very seldom the case!!
 
More horsepower is always desirable but not always necessary. Of the three engines you mention, the Lycoming 0-235 is the most common and is very reliable. There are other considerations. The choice of propeller determines the useful output of the engine. One of the new light weight ground adjustable propellers would be the best choice. The number of square feet combined with wing span is a determining factor for the wing. More sq ft and a longer wing is a big help for lower horsepower and lowest drag. CG control is a big factor. Size, design, and installation of floats is a big factor. Lot's of stuff to consider.

Here are a couple of 2 place side by side seaplanes with 37 horsepower.

1712145211568.png 1712146100839.png
 
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The O-235 engine is a workhorse but is much heavier than a C-85 stroker or C-90 with similar performance. the two Continentals have good low end torque (unlike the O-200) in a very usable range. if you have any CG concerns, it may make a difference. My O-235 in my J5 is about 240 lb dressed vs the C-85 stroker we are building up for a different plane,which should come in just over 200 lb. the Continental O-240 is a really heavy engine as well.
 
rereading your original post, the Rotax 900 series engines are a good match as well. they are indeed real airplane engines with a lot of advantages in an experimental build.
 
I have also seen footage of a Cessna 150G w/O-200 on floats and the performance was understandingly lacking. For this reason I do not see a modified C-90 or O-200 as suitable.
I have flown the 0-200 powered 150 on floats solo and light on fuel. It is doggy getting up on the step, which is where a seaplane's total performance begins. It's water handling and flight characteristics are very good. The doggy part was solved by many people, by converting to the 150 hp 0-320 with the penalty of reducing the legal useful load. The doggy part could be improved by increasing the size of the floats. The 1650 floats do have the correct amount of floatation (1650 pounds in fresh water) for the 150's certified gross weight of 1650. However, the 1650 floats do have notoriously poor performance due to their short forward section ahead of the step (another discussion). If that section was longer, perhaps 8", the getting on the step performance would be much better. I've also flown the 1650 floats on other types of 0-200 powered airplanes with the same observed performance. That plane's performance was improved by lengthening the wing span and changing to an 0-320. The water handling was not changed. The power pulled it out of the bad spots. I also have flown a PA-18-150 on 1650s with two souls onboard (EDO's test plane). It too was a dog. In all of these examples it was the floats, not the engine which dictated the performance.
 
When looking at engines consider cost of overhaul. Your O-235 has several variations. the low compression C series are hard to find parts for. The last one I know of that got new cylinders at overhaul, the cylinders alone were over $10k. The newer higher compression L and N series, not so bad.
 
Go back and re-read what Skywagon just wrote. Differences in float performance can be HUGE, and much more significant than power.

A Continental C-90 is a really hard engine to beat, for the weight. The O-235 is heavy by comparison. As EX, you also have the option of a little "tuning" of the engine, and perhaps, better performing composite props. Or, as noted above, take a REALLY hard look at Rotax engines....there are those making pretty big horsepower and they are really light.....

But, figure out the floats as well. You may have a hot rod engine, but poorly designed floats will limit performance, and vice versa.

MTV
 
More horsepower is always desirable but not always necessary. Of the three engines you mention, the Lycoming 0-235 is the most common and is very reliable. There are other considerations. The choice of propeller determines the useful output of the engine. One of the new light weight ground adjustable propellers would be the best choice. The number of square feet combined with wing span is a determining factor for the wing. More sq ft and a longer wing is a big help for lower horsepower and lowest drag. CG control is a big factor. Size, design, and installation of floats is a big factor. Lot's of stuff to consider.

Here are a couple of 2 place side by side seaplanes with 37 horsepower.

View attachment 105905 View attachment 105906
Skywagon,
Believe that picture of the Aeronca C3 is in Juneau in the late 1930's My father, Tony Schwamm gave float ratings in it back then. I donated the engine from it to the Aviation Museum at lake Hood. thought they were 36HP?
John Schwamm
 
Skywagon,
Believe that picture of the Aeronca C3 is in Juneau in the late 1930's My father, Tony Schwamm gave float ratings in it back then. I donated the engine from it to the Aviation Museum at lake Hood. thought they were 36HP?
John Schwamm
John, It could be, I just googled pictures of a C-3 on floats and picked one. Here's another one they claim is in Borneo.
This is the engine: https://drs.faa.gov/browse/excelExternalWindow/C5DA1220E9131BA9862572C0006F7870.0001 It ranges from 36 -40 hp.
1712171113489.png
 
I have an opportunity to purchase the complete raw materials for an E/AB side-by-side 2-seater and I'm finding my desire to install floats is creating a problem that makes me wonder if I need to abandon the idea of floats or this aircraft. We must begin this effort with an aircraft with low operating costs.

Let me know if you have questions.
Can you give us an idea of what type airplane these parts are supposed to make? It will help us in giving you answers.
 
Here you go skywagon8a...

2-seat
high (wood) wing
tail dragger
target empty weight 800 lbs
Length (4130 tube) 20'8"
Span 33'6"


I do not know the airfoil; it's proprietary.

The only floats I've identified so far are the Edo 1650 and FloatsCz but I have not found any other firms that make them in this weight category. I talked with Ed Peck but he is 82 now and I had difficulty understand him during my phone call with him.

I have read much of the information regarding the stroker C-85 & C-90 vs. the O-200 so I understand the issues generally and need to continue reading. I have discussed these with Klaus but his experience is only with 100LL or 104 octane fuel. Of course, a Rotax is fine but they are extremely costly. Who knows what I can afford in 8-10 years...

I am willing to reduce useful load to a small extent but I think I should be very strict about accepting this option.

Edit - Forgot to attach small Continental performance table (unknown source)
 

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In the subject line...1650 w/floats. I think it best for me to operate within the designers limits. I don't see how I could use an 1800 lb float set...this should be an example of over-floating an aircraft. Bouncing, porpoising, etc. Perhaps a specific installation method would allow these to be used? Murphy floats would certainly be great but this idea concerns me.
 
Buy something similar in weight and desired proven performance to fly while you toil away at building. Getting a box of EXP parts to hold hands and eventually perform to your desires, especially on floats at the projected EW/useful load, is a formidable task not to be taken lightly.

Similar to these in that box?

And a kit> https://www.aircraftspruce.com/catalog/kitspages/christaviaMK1MK2.php

Gary
 
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In the subject line...1650 w/floats. I think it best for me to operate within the designers limits. I don't see how I could use an 1800 lb float set...this should be an example of over-floating an aircraft. Bouncing, porpoising, etc. Perhaps a specific installation method would allow these to be used? Murphy floats would certainly be great but this idea concerns me.
Overfloating is safer than underfloating. Too much overfloating effects flight performance and useful load adversely. If the plans or instructions for your plane include a successful float installation, substituting another model of float should not be an issue as long as you place the step in the same relationship to the plane and mount them at the same angle in relation to the wing. Bouncing, porpoising, etc is in the installation and piloting technique, not size. Stay away from the EDO 1650s. I'll go into detail if you really need to know why. They are well made, just not a good shape. The Murphy forward bottoms look better and would be worth looking at. https://www.murphyair.com/murphy-floats/

Based upon what you've stated, I would recommend to stay with straight floats. Don't consider amphibs due to the added weight. The extra weight to make them amphibs is the equivalent of carrying another person all the time. With your small horsepower and light weight that will be a great penalty.
 
EDO 1400 or1500 Aquas

Glenn
A little too small for a 1650 lb gross airplane. The Aqua 1500 would be barely adequate, but with the low horsepower not advisable. It would sit too low in the water, requiring more power to get on the step. Minimum legal for certified would be 1650 x 0.9 = 1485.
 
In the subject line...1650 w/floats. I think it best for me to operate within the designers limits. I don't see how I could use an 1800 lb float set...this should be an example of over-floating an aircraft. Bouncing, porpoising, etc. Perhaps a specific installation method would allow these to be used? Murphy floats would certainly be great but this idea concerns me.
The Clipper has a gross of 1650 (1732 on floats) and it operates reasonably well on Murphy 1800s. Although the one Clipper I know of with the Murphy floats has an O-320 installed.
 
I missed the "E/AB side-by-side 2-seater" so the 2x2 tandem Christavia is an unlikely suspect.

Gary
 
Experimental Exhibition category?
There is one that got a Field Approval so still Standard. I'm after my PMI to allow me to duplicate it for my PA-16 but he is hesitant. There is another that will be going Experimental Exhibition for the float installation in the near future. Both airplanes are in the same family (father and son).
 
My desire to use the aircraft primarily over undeveloped terrain caused one auto engine conversion manufacturer to recommend I use exclusively an aviation engine.


Let me know if you have questions.

RAVC1;

Would you please be so kind as to let us now who that manufacturer was? I'd like to know who doesn't believe in their product so much so that they'd turn someone away from it. Or seen another way, I'd like to know whose selling a product that they know or believe to be to be inferior. That's a person I don't want to do business with - for any reason. I am beginning a build myself and live and fly in undeveloped and relatively remote (for the lower 48) area so it is important to me.

My first thought for both your situation and mine is an Aeromomentum engine. Each of their options are lighter than legacy engines of similar output. They're made from scratch using all new parts and based on engines that have had huge numbers produced and consequently much development over the years.

I'm a big believer in non traditional engines for aircraft. I believe they hold the biggest potential for safety and operational improvement of any component of GA type aircraft. The old engines work, but we can do so much better. We used to use pencil, paper and slide rule (E6B is just a fancy slide rule) but that's not tolerated these days. I don't see why all those legacy engines are held as sacred.

But of course those are jut my opinions and worth every penny you paid for them. Whatever way you go I wish you the best.
 
dgapilot -

Much to my surprise Murphy tells me the 1800 floats are good up to that weight. This helps but I have to remain concerned about overfloating. I'll certainly listen to skywagon8a has to say. I'm not buying anything tomorrow. However, I should add the 1800 also adds weight that will erode the usable load even with straight floats. No, I would not consider amphibious floats if this is the aircraft I build. There is no float specification for this design. Rather, it is stated the aircraft has the capability to be used with floats. There have been several Mk4 aircraft built with floats in Canada so I have confidence this will work well.

Aqua was the other company I was trying to think of but I cannot determine if they are still in business or they went away as Baumann did. I lost contact with them after they relocated to Florida.

Gary - The Mk2.

Yes,I know of and like AeroMomentum very well. Mark deserves a lot of credit because he tests his products. The AM15 engine choices should meet my needs well. While I am heeding the suggestion I was given by an experimental engine manufacturer I also know many certified pilots disagree with some of this but these are subjective factors. For example, I was also informed it is best to keep it simple and use a carburetor. Many back country pilots I have communicated with find fuel injection just fine. At the same time I have several friends on other forums that agree with the experimental engine manufacturers perspective. I have to approach this with an open mind and keep discussing this openly and be thorough. The O-320 is way too heavy...and some of the comments above suggest the O-235 may be in this category as well. For the time being it appears I need to understand the C-85 stroker and C-90 so this is what I'll do.

However, Catto only supports Continental, Lycoming, and Rotax. That video I posted of the A-65 impresses me like nothing I have seen before so I'm holding tight on Catto for now. Craig is clearly exceptional.
 
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The Mason airfoil looks similar to a NACA 4415...thicker than a Champ's 4412. There's lots of data for both.

Gary
 
Aqua was the other company I was trying to think of but I cannot determine if they are still in business or they went away as Baumann did. I lost contact with them after they relocated to Florida.

However, Catto only supports Continental, Lycoming, and Rotax. That video I posted of the A-65 impresses me like nothing I have seen before so I'm holding tight on Catto for now. Craig is clearly exceptional.
It appears Aqua has been sold, which doesn't surprise me as Terry Clagget would be in his 80s now. https://aquafloat.com

Catto makes a nice prop. However, since you are building an unknown airplane/engine combination with the possibility of also using floats, you will not know exactly which diameter and pitch prop to buy. You could end up trying several different props before you find the correct one. This is why I suggested one of the new lightweight ground adjustable props. They have excellent airfoils which is as important for props as it is for wings.
 
Yes, you are correct. My initial discussions with propeller manufacturers were with IVO and Warp Drive. I have not resurrected those because I want to be able to understand my engine choice(s) better. This is why I posted this thread. I don't mind the experimentation but should be careful I don't bite off too much because it would erode flying time.
 
I looked up the Aeromomentum engine because I'd never heard of it. https://aeromomentum.com I see why it intrigues you. I can also see that it could be a good engine. The company is owned and operated by what appears to be a husband and wife team. She appears to have come from Russia where she was educated. Nothing wrong with that. Both of them appear to be well qualified. The engine components appear to be imported from that part of the world. Nothing wrong with that either. What happens if something happens to them? Will you be able to easily find replacement parts? The whole company could easily go poof, leaving you with a boat anchor. The propeller they recommend is sourced from Ukraine, a war torn country. Another big question mark.

Cessna made thousands of 150s. Other companies also used the 0-200. Parts are plentiful. There are many overhaul shops which know the 0-200. Salvage yards often have good used engines available. I think I would lean in this direction.
 
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